JP2009276655A - Full-color image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a full-color image forming method for faithfully reproducing the color tone of a company logo or a display image on a display which requires high-level color reproducibility. <P>SOLUTION: In the full-color image forming method, plural kinds of toner each containing at least a binder resin and a coloring agent are used, and a toner image formed only with magenta toner has brightness L<SP>*</SP>of 40 to 60, chromaticity a<SP>*</SP>of 60 or more, and chromaticity b<SP>*</SP>of 0 to -80 by L<SP>*</SP>a<SP>*</SP>b<SP>*</SP>color system measurement. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic full-color image forming method.

  Color image formation by electrophotography initially became popular for office use, but recently, due to its speed and ease of handling, it has become popular in the light printing field called on-demand printing (POD). (For example, see Patent Document 1). This is due to the fact that the printing work required for the printing method is no longer necessary, and the image quality required for the printed image can be realized by the electrophotographic method due to the recent development of digital technology. It can be said.

  By the way, in the printing field, a color reproduction standard called “Japan Color Reproduction Printing 2001” is adopted, standardization of the color tone of the printed image is promoted, and it contributes to improvement of communication between printers regarding the color tone. Against this background, color formation that meets the color reproduction standards of “Japan Color Reproduction Printing 2001” is the first target even in color image formation by electrophotography, and full-color image forming apparatuses marketed by various companies have this color. It covers the reproduction standard.

  When producing catalogs and advertisements by digital image processing, there is a strong demand for faithful reproduction of colors with natural colors. In recent years, there have been increasing opportunities to output high-spec digital camera images and images formed on displays, but image formation with the same color tone as images displayed on these digital devices is required. However, since the color tone based on the color reproduction standard of “Japan Color Reproduction Printing 2001” is relatively narrower than the color tone required for these images, especially in the blue region, the color tone of the actually output print and the user There was a discrepancy between the desired color tone. That is, the display image of a display or a digital camera is based on an international standard called sRGB (standard RGB), and the color tone based on this standard is wider than the color tone based on the color reproduction standard of “Japan Color Reproduction Printing 2001”. It was a thing. Therefore, it is difficult to reproduce the color tone of the image displayed on the display as it is with a printer.

  From such a background, the need to reproduce the color tone of the display image on the display as it is on the print image has increased, and studies have been made on techniques for expanding the color reproduction region of the color material used for forming the print image.

Under such circumstances, studies have been made to increase the color tone of blue by giving the cyan colorant a bluish color (see, for example, Patent Documents 2 and 3), but sufficient color gamut expansion is realized. I couldn't. Therefore, it can be said that image formation requiring high color reproducibility such as printing out the color tone of an image displayed on a display or printing a company logo mark has been still under development.
JP 2005-157314 A JP-A-5-239368 JP 2006-63171 A

  The present invention provides an electrophotographic full color image forming method capable of faithfully reproducing a blue color tone. Specifically, an object is to provide a full-color image forming method capable of faithfully reproducing the color tone of an image displayed on a company logo mark or display that requires high color reproducibility. It is.

  The present inventor has found that the above-described problem can be solved by any of the configurations described below.

The invention described in claim 1
“In a full-color image forming method for forming a full-color image using a plurality of toners containing at least a binder resin and a colorant,
Lightness ^{L *} of 40 to 60 by ^L * ^a * ^{b *} color system measured the toner image formed only by the magenta toner, the chromaticity ^{a *} is 60 or more, the chromaticity ^{b *} is 0-80 A full color image forming method. ].

According to a second aspect of the present invention, “the full color image forming method according to the first aspect, wherein the chromaticity a ^* is 60 or more and 100 or less. ].

The invention according to claim 3
The full color image forming method according to claim 1 or 2, wherein a cyan toner having at least one cyan colorant represented by the following general formula (1) or general formula (2) is used.

[Wherein R ₁ represents an organic group, and the organic group may be a hetero group. ]

[Wherein R ₂ represents a hydrogen atom or an organic group. ]].

In the present invention, by specifying L ^* a ^* b ^* color system measurement lightness L ^* , chromaticity a ^* and b ^* of a toner image formed only with magenta toner, the blue color tone is faithfully reproduced. It has been found that a full-color image forming method that can be performed is realized. Therefore, according to the present invention, a blue company logo mark and a blue display image on a display can be faithfully reproduced. For example, as described in the examples described later, a blue-violet display image, which is difficult to be identified by a conventional print image, can be reproduced faithfully according to the present invention.

  The present invention relates to a full-color image forming method for forming a full-color image using a plurality of toners containing at least a binder resin and a colorant.

In the present invention, when the color tone of a toner image formed only of magenta toner containing at least a binder resin and a colorant is measured by the L ^* a ^* b ^* color system, the color tone has a specific relationship. It has been found that the effects of the present invention are expressed. That is, the present inventor has determined that the color tone of a toner image formed only with magenta toner is L ^* a ^* b ^* color system measurement, lightness L ^* is 40 to 60, chromaticity a ^* is 60 or more, chromaticity b It has been found that the effect of the present invention is exhibited when ^* is 0 to -80.

As described above, the present inventor specifies the lightness L ^* and chromaticity a ^* and b ^* of a toner image formed only with magenta toner as described above, and thus a blue color reproduction region is conventionally defined by the toner image. It was found that it can cover more widely. In the prior art, it was considered to expand the blue color reproduction region by improving cyan toner, but in the present invention, attention is paid to magenta toner, which is another toner capable of forming blue. They found that the blue color reproduction region can be expanded.

The L ^* a ^* b ^* color system used in the present invention will be described.

In the present invention, when the color tone of a toner image formed only with magenta toner is measured in the L ^* a ^* b ^* color system, the values of L ^* , a ^* , and b ^* are within the above-described ranges. It has been found that the effects of the present invention are manifested.

Here, the L ^* a ^* b ^* color system is one of the means for expressing the color numerically, so that any color tone can be expressed numerically via the three coordinate axes of L ^* , a ^* and b ^*. Yes. L ^* is called brightness and corresponds to the coordinate in the z-axis direction, and a ^* representing the hue in the red-green direction and b ^* representing the hue in the yellow-blue direction are the x-axis direction and the y-axis direction, respectively. Corresponds to the coordinates of. That is, the x-axis-y-axis plane is represented by a ^* and b ^* , and the + (plus) direction of the x-axis indicated by a ^* is the red direction, and the − (minus) direction of the x-axis is the green direction. . Further, the + (plus) direction of the y axis indicated by b ^* is the yellow direction, and the-(minus) direction of the y axis is the blue direction. The lightness represented by L ^* refers to the relative brightness of the color, and the hue represented by a ^* , b ^* refers to a hue such as red, yellow, green, blue, purple, etc. That's what it says.

In the L ^* a ^* b ^* color system measurement, the color tone of the toner image can be specified by the hue angle h and the saturation C ^* . Here, the hue angle h is, for example, a half connecting a certain coordinate point (a, b) and the origin O on the x-axis-y-axis plane representing the relationship between hue and saturation when the lightness takes a certain value. An angle formed by a straight line and a straight line extending in the + direction (red direction) of the x axis in the counterclockwise direction from the + direction (red direction) of the x axis is calculated by the following equation (1).

Formula (1): Hue angle h = tan ⁻¹ (b ^* / a ^* )
In the x-axis-y-axis plane, the-(minus) direction of the x-axis indicated by a ^* is the green direction, and the + (plus) direction of the y-axis indicated by b ^* is the yellow direction. The-(minus) direction of the axis is the blue direction.

The saturation C ^* means a distance from the coordinate point (a, b) and the origin O, and is calculated by the following equation (2).

Formula (2): Saturation C ^* = [(a ^* ) ² + (b ^* ) ² ] ^1/2
Specific measurement means using the L ^* a ^* b ^* color system includes, for example, a method of measuring using a spectrophotometer “Gretag Macbeth Spectrolino” (manufactured by Gretag Macbeth). As with the measurement of the reflection spectrum, a D65 light source is used as the light source, a φ4 mm reflection measurement aperture is used, the measurement wavelength range is 380 to 730 nm at 10 nm intervals, the viewing angle (observer) is 2 °, and white for reference adjustment This is done under conditions using tiles.

In the present invention, the magenta toner is formed by mixing the following three colorants, color assistants, and colorable metals in the toner particles, thereby forming a magenta toner image having the above-described color tone. be able to. That is, the L ^* a ^* b ^* color system measurement brightness L ^{* of the} toner image formed with only magenta toner is 60 to 80, the chromaticity a ^* is 55 or more, and the chromaticity b ^* is -10 to -60. A toner image having a color tone is formed. Hereinafter, the colorant, the color assistant, and the colorable metal used in the magenta toner for forming the toner image having the above-described color tone will be described.

<Colorant>
The colorant that can be used in the present invention is a compound containing a heterocyclic ring having a plurality of nitrogen atoms in the structure, and specifically includes the following compounds.

  Among the above compounds, the compound represented by (1-13) is particularly preferable.

<Coloring aid>
Moreover, the coloring adjuvant which can be used for this invention is a compound which has a carbonyl bond (C = O, C-O) in a structure, Specifically, the following compounds are mentioned.

  Among the above compounds, the compound represented by (3-16) is particularly preferable.

<Colorable metal>
Furthermore, examples of the colorable metal that can be used in the present invention include copper (Cu), cobalt (Co), zinc (Zn), nickel (Ni), and the like, among which copper (Cu) is preferable.

  In the present invention, in addition to the above-mentioned colorant, coloring aid, and coloring metal mixed in the toner particles, C.I. I. Known dyes such as Solvent Red 49 and C.I. I. It is also possible to obtain the color tone using a known pigment such as CI Pigment Red 122.

  Next, colorants other than the colorant for magenta toner used in the full color image forming method according to the present invention will be described. First, as the colorant for black toner, carbon black, magnetic material, titanium black, etc. can be used, and as the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, etc. can be used. . Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, and ferromagnetic materials that do not contain ferromagnetic metals but are heat treated. An alloy or the like can be used. Examples of alloys that exhibit ferromagnetism by heat treatment include alloys called Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

  On the other hand, as a yellow colorant for yellow toner, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, etc., and C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, etc. can be used, and mixtures thereof can also be used. Among these, C.I. I. Pigment Yellow 74 is particularly preferable.

  Examples of cyan colorants for cyan toner include C.I. I. In addition to known ones such as CI Pigment Blue 15: 3, it is preferable to use a cyan toner having at least one cyan colorant having a structure represented by the following general formula (1) or general formula (2).

R ₁ in the general formula (1) represents an organic group, and this organic group R ₁ is a hetero group, that is, a group having a structure formed from atoms such as silicon atoms in addition to carbon atoms and hydrogen atoms. May be.

R ₂ in the general formula (2) represents a hydrogen atom or an organic group.

  Specific examples of the cyan colorant represented by the general formula (1) or the general formula (2) include cyan colorants 1 to 3 shown below.

  The number average primary particle diameter of these colorants in a dispersed state in the toner varies depending on the type, but is preferably about 10 to 200 nm. The number average primary particle size was determined by using a photograph in which the cross section of the toner was magnified 50,000 times with a transmission electron microscope, measuring the diameter of the colorant particles in the ferret direction, and observing 10 toner particles. Let the arithmetic average diameter of the particle diameters be the number average primary particle diameter.

  The amount of the colorant added to the toner is preferably 1 to 10% by mass in the toner, and more preferably 2 to 8% by mass. If the amount is less than 1% by mass, the coloring power of the toner may be insufficient. If the amount exceeds 10% by mass, the colorant may be released from the toner or may adhere to the carrier. There is a concern that it will affect.

  Next, a method for producing toners including magenta toner used in the full color image forming method according to the present invention will be described. Examples of the method for producing the toner used in the present invention include kneading / pulverization method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, miniemulsion polymerization aggregation method, encapsulation method, and other known methods. Can be mentioned. Among them, the emulsion polymerization aggregation method is preferable from the viewpoints of obtaining a toner having a small particle diameter in order to realize high image quality of the image, and from the viewpoint of manufacturing cost and manufacturing stability. In the emulsion polymerization aggregation method, a dispersion of fine particles (hereinafter also referred to as “binder resin fine particles”) made of a binder resin produced by an emulsion polymerization method is mixed with a dispersion of toner particle components such as colorant fine particles. The particles are slowly agglomerated while maintaining a balance between the repulsive force on the surface of the fine particles by adjusting the pH and the aggregating force due to the addition of an aggregating agent made of an electrolyte, and heating is performed simultaneously while controlling the average particle size and particle size distribution. This is a method for producing toner particles by controlling the shape by fusing fine particles by stirring.

  As a method for producing the toner used in the present invention, the binder resin fine particles formed when the emulsion polymerization aggregation method is used may be composed of two or more layers composed of binder resins having different compositions. A polymerization initiator and a polymerizable monomer are added to the dispersion of the first resin particles prepared by emulsion polymerization treatment (first stage polymerization) according to a conventional method, and this system is polymerized (second stage polymerization). Polymerization) can be employed.

  Further, as described later, the core-shell structured toner particles are produced by first assembling, aggregating and fusing the core binder resin fine particles and the colorant fine particles, and then producing the core particles. It is obtained by adding a shell resin fine particle for forming a shell layer in the dispersion, and aggregating and fusing the shell resin fine particle on the surface of the core particle to form a shell layer covering the core particle surface. Can do.

  The shape of the core particles constituting the toner particles having the core-shell structure can be adjusted, for example, by controlling the heating temperature in the aggregation / fusion process, the heating temperature in the first aging process, and the heating time. In particular, by controlling the heating time in the first ripening step, the circularity of the associated particles can be adjusted with certainty.

  The core particles are obtained by, for example, finely dispersing a polymerizable monomer that forms a core binder resin that constitutes the core particles in an aqueous medium, and then performing polymerization by a miniemulsion polymerization method. A salting-out / fusion method in which the core binder resin fine particles and the colorant fine particles formed through the step of polymerizing are salted out / fused as described later is preferably used.

[Binder resin]
When the toner particles constituting the toner used in the present invention are produced by, for example, a pulverization method or a dissolution suspension method, a styrene resin or (meth) acrylic resin is used as a binder resin constituting the toner. Resin, styrene- (meth) acrylic copolymer resin, vinyl resin such as olefin resin, polyester resin, polyamide resin, polycarbonate resin, polyether resin, polyvinyl acetate resin, polysulfone resin, epoxy resin And publicly known resins such as polyurethane resins and urea resins.

  In addition, when the toner particles constituting the toner used in the present invention are produced by, for example, suspension polymerization, miniemulsion polymerization aggregation, emulsion polymerization aggregation, etc., the binder resin constituting the toner is changed. Examples of the polymerizable monomer to be obtained include the following.

  Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn- Styrene or styrene derivatives such as hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene; methyl methacrylate, ethyl methacrylate, n-methacrylate Butyl, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethyl methacrylate Methacrylic acid ester derivatives such as aminoethyl; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid ester derivatives such as stearyl acid, lauryl acrylate and phenyl acrylate; olefins such as ethylene, propylene and isobutylene; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl methyl ether and vinyl ethyl ether Vinyl ethers such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like; N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone Vinyl compounds such as vinyl naphthalene and vinyl pyridine; and vinyl monomers such as acrylic acid and methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers can be used alone or in combination of two or more.

  Moreover, it is preferable to use combining what has an ionic dissociation group as a polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, or a phosphoric acid group as a constituent group of the monomer. Specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allylsulfosuccinic acid, 2-acrylamide- Examples include 2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate, and 3-chloro-2-acid phosphooxypropyl methacrylate.

  Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl It is possible to form a resin having a crosslinked structure using polyfunctional vinyls such as glycol diacrylate.

  When the toner particles have a core-shell structure, styrene-acrylic copolymer resins are preferable as the core binder resin and the shell resin, respectively.

  When the core binder resin is a copolymer, examples of the polymerizable monomer for obtaining the copolymer include propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. These are preferable for lowering the glass transition temperature (Tg) of the copolymer. In addition to the specific examples given above, such polymerizable monomers may have acid anhydrides or vinyl carboxylic acid metal salt forms.

  When the shell resin is formed of a copolymer, the glass transition temperature (Tg) of the obtained copolymer, such as styrene, methyl methacrylate, methacrylic acid, etc., as the polymerizable monomer for obtaining the copolymer. It is preferable that the thing which can make high is included.

  Such a polymerizable monomer for forming a shell resin is similar to the polymerizable monomer for forming a core, in addition to the above specific examples, in addition to acid anhydrides or vinyl carboxylic acid metal salts. It may have a form.

  The binder resin constituting the toner used in the present invention is, for example, a magenta toner when the toner has a core-shell structure manufactured by an emulsion polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, or the like. The molecular weights of the respective binder resins forming the core particles and the shell layer constituting the particles are preferably as follows.

  That is, the weight average molecular weight (Mw) by gel permeation chromatography (GPC) in which the binder resin constituting the core particles is soluble in tetrahydrofuran (THF) is in the range of 5,000 to 30,000, and the shell layer It is preferable that the weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) of the THF-soluble binder resin is in the range of 10,000 to 80,000, more preferably the core. The weight average molecular weight (Mw) of the binder resin constituting the particles is in the range of 15,000 to 28,000, and the weight average molecular weight (Mw) of the binder resin constituting the shell layer is in the range of 10,000 to 50,000, respectively. It has a peak molecular weight.

  Further, the glass transition temperature (Tg) of the binder resin constituting the core particles is preferably 10 to 50 ° C., preferably 25 to 48 ° C., and the glass transition temperature (Tg) of the binder resin constituting the shell layer. Is 38 to 64 ° C, preferably 40 to 54 ° C.

  On the other hand, when the binder resin constituting the toner used in the present invention is not of a core-shell structure, for example, the number average molecular weight (Mn) by gel permeation chromatography (GPC) of THF-soluble matter is The ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 2.0 to 6.0, preferably 2 to 3,000 to 6,000, more preferably 3,500 to 5,500. The glass transition temperature (Tg) is from 50 to 70 ° C, preferably from 55 to 70 ° C.

The molecular weight measurement by GPC was performed as follows. That is, an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolum + TSKgelSuperHZM-M triple” (manufactured by Tosoh Corporation) are used. While maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) as a carrier solvent was flowed at a flow rate of 0.2 ml / min, and the measurement sample was treated at a room temperature for 5 minutes using an ultrasonic disperser at a concentration of 1 mg / min. Dissolve in tetrahydrofuran to make ml. Next, a sample solution is obtained by processing with a membrane filter having a pore size of 0.2 μm, and 10 μl of this sample solution is injected into the apparatus together with the carrier solvent and detected using a refractive index detector (RI detector). The molecular weight distribution of the measurement sample is calculated from a calibration prepared using monodisperse polystyrene standard particles. The standard polystyrene sample for preparing a calibration curve has a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1. manufactured by Pressure Chemical. 1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ are used. When preparing a calibration curve, at least about 10 standard polystyrene samples are measured.

  The glass transition temperature (Tg) of the binder resin is determined using a differential scanning calorimeter “DSC-7 (manufactured by PerkinElmer)” and a thermal analyzer controller “TAC7 / DX (manufactured by PerkinElmer)”. It is to be measured. Specifically, first, 4.50 mg of toner is sealed in an aluminum pan “Kit No. 0219-0041”, which is set in a sample holder of “DSC-7”, and is made of empty aluminum for reference measurement. Use bread. Next, heat-cool-heat temperature control is performed under the measurement conditions of a measurement temperature of 0 ° C. to 200 ° C., a temperature increase rate of 10 ° C./min, and a temperature decrease rate of 10 ° C./min. Get data in Heat. And the intersection of the extended line of the baseline before the rise of the first endothermic peak and the tangent showing the maximum inclination between the rising portion of the first endothermic peak and the peak apex is shown as the glass transition temperature (Tg). . 1st. When heating the heat, hold at 200 ° C. for 5 minutes.

When the toner used in the present invention has, for example, a core-shell structure, specifically, it can be produced through the following steps. That is,
(1) a colorant fine particle dispersion preparing step for preparing a dispersion of colorant fine particles in which a colorant is dispersed in the form of fine particles;
(2-1) A core binder resin fine particle polymerization step for obtaining a binder resin fine particle comprising a core binder resin containing a release agent, a charge control agent and the like as required, and preparing this dispersion;
(2-2) Shell resin fine particle polymerization step for obtaining resin fine particles made of shell resin and preparing this dispersion;
(3) Aggregation / fusion process for aggregating and fusing core binder resin fine particles and colorant fine particles in an aqueous medium to form associated particles to be core particles (4) Aging the associated particles with thermal energy First ripening step for controlling the shape and obtaining the core particles (5) Add the shell resin fine particles to form the shell layer into the core particle dispersion, and agglomerate the shell resin fine particles on the surface of the core particles Shell layer forming step of forming core-shell structured particles by fusing (6) Second ripening step (7) in which core-shell structured particles are aged with thermal energy to control the shape and obtain core-shell structured magenta colored particles (7 ) Solid-liquid separation of the magenta colored particles from the cooled dispersion of magenta colored particles (aqueous medium), and filtration and washing step to remove the surfactant from the magenta colored particles. Drying step of drying the magenta colored particles are composed of a drying step if necessary.

  Note that after the drying step, (9) an external additive treatment step of adding toner to the dried colored particles to obtain toner particles may be added. Hereinafter, each of the above manufacturing steps for producing a toner having a core-shell structure will be described.

(1) Colorant dispersion preparation step In this step, dispersion of the colorant fine particles in which the colorant is dispersed in the form of fine particles by adding a pigment as a colorant to an aqueous medium and dispersing it with a disperser. Processing to prepare the liquid is performed. Specifically, the colorant dispersion treatment is performed in an aqueous medium in which the surfactant concentration is set to a critical micelle concentration (CMC) or more as described later. The disperser used for the dispersion treatment is not particularly limited, but is preferably a media type such as an ultrasonic disperser, a mechanical homogenizer, a manton gorin, a pressure disperser such as a pressure homogenizer, a sand grinder, a Getzman mill or a diamond fine mill. Examples include a disperser.

  The dispersion diameter of the colorant fine particles in the colorant fine particle dispersion is preferably 40 to 200 nm in terms of volume-based median diameter.

(2-1) Core Binder Resin Fine Particle Polymerization Step In this step, a dispersion of binder resin fine particles made of a core binder resin containing a release agent, a charge control agent, etc., if necessary after performing a polymerization treatment. The process of preparing is performed.

  In a preferred example of the polymerization treatment in this step, a polymerizable unit containing a release agent, a charge control agent, or the like, if necessary, in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less. A monomer solution is added, mechanical energy is applied to form droplets, then a water-soluble polymerization initiator is added, and the polymerization reaction proceeds in the droplets. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a process, it is essential to perform mechanical emulsification (formation of droplets) by applying mechanical energy. Examples of the mechanical energy applying means include strong stirring such as homomixer, ultrasonic wave, and manton gorin, or ultrasonic vibration energy applying means.

[Surfactant]
Here, the surfactant used in the aqueous medium used at the time of polymerization of the colorant fine particle dispersion and the core binder resin fine particles will be described.

  The surfactant is not particularly limited, but sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate), sulfate ester salt (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate). Ionic surfactants such as fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, etc.) It can be illustrated as. Also, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester, etc. Nonionic surfactants can also be used.

  Hereinafter, the polymerization initiator, chain transfer agent, release agent, and charge control agent used in the core binder resin fine particle polymerization step will be described.

(Polymerization initiator)
Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

  Examples of the oil-soluble radical polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or diazo polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl Peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4 4-t-butylperoxycyclohexyl) propa Tris - such as (t-butylperoxy) polymeric initiator having a side chain a peroxide-based polymerization initiator or a peroxide such as triazine.

[Chain transfer agent]
In this polymerization step, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the obtained core binder resin. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, and mercaptopropionate esters such as n-octyl-3-mercaptopropionate. , Terpinolene, α-methylstyrene dimer and the like are used.

〔wax〕
The toner particles constituting the toner used in the present invention may contain a wax that contributes to the suppression of the offset phenomenon. Here, the wax is not particularly limited, and examples thereof include polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, carnauba wax, sazol wax, rice wax, and candelilla wax. Can do.

The content ratio of the wax in the toner particles is usually 0.5 to 5 parts by mass, preferably 1 to 3 parts by mass with respect to 100 parts by mass of the binder resin. When the content of the release agent is less than 0.5 parts by mass with respect to 100 parts by mass of the binder resin, a sufficient offset prevention effect cannot be obtained, while on the other hand, 5 parts by mass with respect to 100 parts by mass of the binder resin. If it is larger, the obtained magenta toner has low translucency and color reproducibility.
(2-2) Shell Resin Fine Particle Polymerization Step In this step, a polymerization treatment is performed in the same manner as the core binder resin fine particle polymerization step (2-1) above to prepare a dispersion of shell resin fine particles made of a shell resin. Processing is performed.

(3) Aggregation / fusion process This process is a process of aggregating and fusing the core binder resin fine particles and the colorant fine particles in an aqueous medium to form associated particles to be core particles. As a method of aggregation and fusion in this step, the colorant fine particles obtained by the colorant dispersion preparation step (1) and the core obtained by the core binder resin fine particle polymerization step (2-1). A salting out / fusion method using fine binder resin particles is preferred. In the agglomeration / fusion step, the core additive resin fine particles and the colorant fine particles and the internal additive fine particles such as the release agent fine particles and the charge control agent can be agglomerated and fused.

  Here, “salting out / fusing” means that agglomeration and fusing are carried out in parallel, and when the particles grow to a desired particle diameter, an agglomeration terminator is added to stop the particle growth, and further if necessary. This means that heating for controlling the particle shape is continued.

  In the salting-out / fusion method, a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like is critical in an aqueous medium in which core binder resin fine particles and colorant fine particles are present. Added as a flocculant having an aggregation concentration or higher, and then heated to a temperature above the glass transition temperature of the core binder resin fine particles and above the melting peak temperature (° C.) of the core binder resin fine particles and the colorant fine particles. By doing so, salting-out proceeds, and at the same time, aggregation and fusion are performed. Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used.

  When the coagulation / fusion process is performed by salting out / fusion, it is preferable to shorten the time allowed to stand after adding the salting-out agent as much as possible. The reason for this is not clear, but the aggregation state of the particles fluctuates depending on the standing time after salting out, and the particle size distribution becomes unstable and the surface property of the fused toner fluctuates. appear. Further, the temperature for adding the salting-out agent needs to be at least the glass transition temperature of the core binder resin fine particles. The reason for this is that if the temperature at which the salting-out agent is added is equal to or higher than the glass transition temperature of the core binder resin fine particles, the salting out / fusion of the core binder resin fine particles proceeds rapidly, but the particle size is controlled. It cannot be performed, and there arises a problem that particles having a large particle size are generated. Although the range of this addition temperature should just be below the glass transition temperature of resin, generally it is 5-55 degreeC, Preferably it is 10-45 degreeC.

  Further, the salting-out agent is added at a temperature lower than the glass transition temperature of the core binder resin fine particles, and then the temperature is raised as quickly as possible to be higher than the glass transition temperature of the core binder resin fine particles, and the core binder resin fine particles and Heat to a temperature equal to or higher than the melting peak temperature (° C.) of the colorant fine particles. The time until this temperature rise is preferably less than 1 hour. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 0.25 ° C./min or more. The upper limit is not particularly clear, but if the temperature is increased instantaneously, salting out proceeds rapidly, so there is a problem that particle size control is difficult, and 5 ° C./min or less is preferable. By the salting-out / fusion method described above, a dispersion of associated particles (core particles) obtained by salting-out / fusion of the core binder resin fine particles and arbitrary fine particles is obtained.

  The “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Of these, alcohol-based organic solvents that do not dissolve the produced resin are preferred.

(4) First aging step In this step, an aging treatment for aging associated particles with thermal energy is performed. By controlling the heating temperature in the agglomeration and fusion process, and particularly the heating temperature and time in the first aging process, the core particle surface formed with a uniform particle size and a narrow distribution has a smooth but uniform shape. It can be controlled to have it. Specifically, the heating temperature is lowered in the aggregation / fusion process to suppress the progress of fusion between the core binder resin fine particles to promote homogenization, and the heating temperature is lowered in the first aging process, In addition, the surface of the core particles is controlled to have a uniform shape by increasing the time.

(5) Shell layer forming step In this shell layer forming step, a shell resin fine particle dispersion is added to the core particle dispersion to cause the shell resin fine particles to agglomerate and fuse to the surface of the core particles. A shelling treatment is performed in which the shell resin fine particles are coated to form core-shell structured particles.

  This shell layer forming step is a preferable production condition for imparting both low temperature fixability and heat resistant storage stability. Further, when forming a color image, it is preferable to form this shell layer in order to obtain high color reproducibility for the secondary color.

  Specifically, the dispersion of core resin is added to the dispersion of core particles while maintaining the heating temperature in the above-described aggregation / fusion process and the first aging process, and it takes several hours while continuing the heating and stirring. Then, the shell resin fine particles are slowly coated on the surface of the core particles to form core-shell structured particles. The heating and stirring time is preferably 1 to 7 hours, particularly preferably 3 to 5 hours.

(6) Second aging step When the core-shell structured particles have reached a predetermined particle size by the shell layer forming step, a terminator such as sodium chloride is added to stop the particle growth, and the particles are then adhered to the core particles. In order to fuse the shell resin fine particles, heating and stirring are continued for several hours. And the thickness of the layer by the shell resin fine particles which coat | cover the surface of a core particle shall be 100-300 nm. In this manner, resin fine particles are fixed to the surface of the core particles to form a shell layer, and magenta colored particles having a rounded and uniform core-shell structure are formed.

  In the method for producing the magenta toner used in the present invention, the shape of the magenta colored particles can be controlled in the true sphere direction by setting the time of the second ripening step longer or by setting the ripening temperature higher. Is possible.

(7) Filtration and Washing Step In this step, first, the magenta colored particle dispersion is cooled. As a cooling treatment condition, it is preferable to cool at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

  Next, the magenta colored particles are solid-liquid separated from the dispersion of magenta colored particles cooled to a predetermined temperature, and then the solid-liquid separated toner cake (aggregation of magenta colored particles in a wet state is aggregated in a cake shape) And a cleaning treatment for removing deposits such as a surfactant and a salting-out agent. Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

(8) Drying step This step is a step of drying the washed magenta toner cake to obtain dried magenta colored particles. 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 moisture content of the dried magenta colored particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the magenta colored particles subjected to the drying treatment are aggregated with weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(9) External Addition Processing Step The magenta colored particles used as the magenta toner used in the present invention can constitute magenta toner particles as they are, but the purpose is to improve fluidity, chargeability and cleaning properties. And magenta toner particles obtained by adding a so-called external additive. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles, and aliphatic metal salts can be used.

  As the inorganic fine particles, inorganic oxide particles such as silica, titania, and alumina are preferably used, and these inorganic fine particles are preferably subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, or the like.

  As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As the organic fine particles, polystyrene, polymethyl methacrylate, styrene-methyl methacrylate copolymer can be used.

  The addition ratio of these external additives is a ratio of 0.1 to 5.0% by mass, preferably 0.5 to 4.0% by mass in the magenta toner. Further, various external additives may be used in combination.

  Through the above steps, a core-shell structured toner that can be used in the full-color image forming method according to the present invention can be produced.

[Recording material]
The recording material used in the full-color image forming method according to the present invention is not particularly limited as long as it is a support capable of holding a toner image, and a known material can be used. Specifically, various types of support such as coated paper such as plain paper, fine paper, art paper or coated paper from thin paper to thick paper, commercially available Japanese paper or postcard paper, OHP plastic film, cloth, etc. There is a body.

(Developer)
In the present invention, the toner described above can be used as a two-component developer that forms an image using a carrier, or a non-magnetic one-component developer that forms an image using only a toner.

  When toner is used as a two-component developer together with a carrier, for example, a full-color print can be created at high speed by a tandem image forming apparatus described later.

  In addition, carriers that are magnetic particles used when used as a two-component developer are conventionally known, for example, metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead. It is possible to use materials. Among these, ferrite particles are preferable. The carrier has a volume average particle size of preferably 15 to 100 μm, more preferably 25 to 80 μm.

  When used as a non-magnetic one-component developer composed only of toner, the toner is charged by sliding and pressing the charging member and the developing roller surface during image formation. Image formation by the non-magnetic one-component development method can simplify the structure of the developing device, and thus has an advantage that the entire image forming device can be made compact.

  Next, an example of an image forming apparatus that realizes the full-color image forming method according to the present invention will be described. FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus capable of forming a full color image with a two-component developer.

  In FIG. 1, 1Y, 1M, 1C, 1K are photosensitive members, 4Y, 4M, 4C, 4K are developing devices (developing means), 5Y, 5M, 5C, 5K are primary transfer rolls as primary transfer means, 5A is a secondary transfer roll as a secondary transfer means, 6Y, 6M, 6C and 6K are cleaning devices, 7 is an intermediate transfer body unit, 24 is a heat roll 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. It has an endless belt-like paper feeding and conveying means 21 for conveying and a heat roll 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.

  An image forming unit 10Y that forms a yellow image as one of the different color toner images formed on each photoconductor is arranged around a drum-shaped photoconductor 1Y as the first photoconductor and the photoconductor 1Y. The charging unit 2Y, the exposure unit 3Y, the developing unit 4Y, the primary transfer roll 5Y as the primary transfer unit, and the cleaning unit 6Y are provided. The image forming unit 10M that forms a magenta image as another different color toner image includes a drum-shaped photoconductor 1M as a first photoconductor, and a charge disposed around the photoconductor 1M. Means 2M, exposure means 3M, developing means 4M, primary transfer roll 5M as primary transfer means, and cleaning means 6M. In addition, an image forming unit 10C that forms a cyan image as one of toner images of different colors is a drum-shaped photoconductor 1C as a first photoconductor, and a charge disposed around the photoconductor 1C. Means 2C, exposure means 3C, developing means 4C, primary transfer roll 5C as primary transfer means, and cleaning means 6C.

  Furthermore, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around the photosensitive member 1K as a drum-shaped photosensitive member 1K as a first photosensitive member. It has a charging means 2K, an exposure means 3K, a developing means 4K, a primary transfer roll 5K as a primary transfer means, and a cleaning means 6K.

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

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred and synthesized on the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rolls 5Y, 5M, 5C, and 5K. A color 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 rolls 22 A, 22 B, 22 C, 22 D, and a registration roll 23, and is secondary A color image is transferred onto the recording member P at a time by being conveyed to a secondary transfer roll 5A as a transfer means. The recording member P to which the color image has been transferred is fixed by the heat roll type fixing device 24, is sandwiched by the paper discharge roll 25, and is placed on the 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 roll 5A, the residual toner is removed from the endless belt-shaped intermediate transfer body 70 from which the recording member P is separated by the curvature by the cleaning means 6A.

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

  The secondary transfer roll 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 roll 5A and secondary transfer is performed.

  In this way, a toner image is formed on the photoreceptors 1Y, 1M, 1C, 1R, 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 recorded. The toner is transferred to P, and fixed and fixed by pressure and heating by the fixing device 24. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P are subjected to the above-described charging, exposure, and development cycle after the toner remaining on the photoreceptor is removed by the cleaning device 6A. The next image formation is performed.

  A full-color image forming method using a non-magnetic one-component developer includes, for example, an image forming apparatus in which the developing means 4 for the two-component developer described above is replaced with a known developing means for a non-magnetic one-component developer. It can be realized by using it.

  Further, the fixing method that can be carried out by the image forming method according to the present invention is not particularly limited, and can be handled by a known fixing method. Known fixing methods include a roller fixing method comprising a heating roller and a pressure roller, a fixing method comprising a heating roller and a pressure belt, a fixing method comprising a heating belt and a pressure roller, and a heating belt and a pressure belt. Belt fixing method, and the like, and any method may be used. As the heating method, any known heating method such as a halogen lamp method or an IH fixing method can be employed.

1. Preparation of “Magenta Colorant Dispersion 1-7” (1) Preparation of “Magenta Colorant Dispersion 1” A solution obtained by stirring and dissolving 11.5 parts by mass of sodium n-dodecyl sulfate in 160 parts by mass of ion-exchanged water. While stirring, the following magenta colorant was gradually added to the solution.

Colorant compound (1-13) 22.5 parts by mass Cu complex compound 12.5 parts by mass of the following color assistant (3-16)

Next, a “magenta colorant dispersion liquid 1” was prepared by carrying out a dispersion treatment using a stirring device “Clearmix W Motion CLM-0.8” (manufactured by M Technique Co., Ltd.).
(2) Preparation of “Magenta Colorant Dispersion 2” In the preparation of “Magenta Colorant Dispersion 1”, the same procedure was followed except that the colorant compound and the colorant Cu complex compound were changed to the following. A magenta colorant dispersion 2 ”was prepared.

20.5 parts by mass of the colorant compound (1-2) 11.5 parts by mass of the Cu complex compound of the following color assistant (3-13)

(3) Preparation of “Magenta Colorant Dispersion 3-7” In the preparation of “Magenta Colorant Dispersion 1”, the following colorant was used in place of the colorant compound and the coloring aid Cu complex compound. “Magenta colorant dispersion 3” was prepared in the same procedure.

C. I. Solvent Red 49 22.4 parts by mass C.I. I. Pigment Red 122 9.6 parts by mass C.I. used in “Magenta Colorant Dispersion 3” was used. I. Solvent Red 49 and C.I. I. “Magenta colorant dispersion 4” was prepared in the same procedure except that the amount of pigment red 122 was changed to 16.0 parts by mass.

  Further, “Magenta Colorant Dispersion 5” was prepared in the same procedure except that the colorant used in “Magenta Colorant Dispersion 3” was changed as follows.

C. I. Pigment Red 254 16.0 parts by mass C.I. I. Pigment Red 184 16.0 parts by mass C.I. used in “Magenta Colorant Dispersion 3” I. The amount of Pigment Red 122 added was changed to 19.2 parts by mass. I. Instead of Solvent Red 49, C.I. I. 12.8 parts by mass of Pigment Red 238 was added. Otherwise, “Magenta Colorant Dispersion 6” was prepared in the same procedure.

  Furthermore, C.I. used in “Magenta Colorant Dispersion 3” was used. I. The amount of Pigment Red 122 added was changed to 19.2 parts by mass. I. Instead of Solvent Red 49, C.I. I. 12.8 parts by mass of Pigment Red 150 was added. Otherwise, “Magenta Colorant Dispersion 7” was prepared in the same procedure.

2. 2. Production of “Magenta Toner 1-7” 2-1. Production of “core-forming resin particle 1” [Production of “core-forming resin particle 1”]
“Core-forming resin fine particles 1” were prepared by the following procedure.

(A) First-stage polymerization 4 parts by mass of an anionic surfactant shown below (Structural Formula 1) together with 3040 parts by mass of ion-exchanged water are charged into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device. Then, a surfactant aqueous solution was prepared.

(Structural Formula 1) C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na
A polymerization initiator solution in which 10 parts by mass of potassium persulfate (KPS) was dissolved in 400 parts by mass of ion-exchanged water was added to the surfactant aqueous solution, and the temperature was raised to 75 ° C. The resulting monomer mixture was dropped into the reaction vessel over 1 hour.

Styrene 532 parts by mass n-butyl acrylate 200 parts by mass Methacrylic acid 68 parts by mass n-octyl mercaptan 16.4 parts by mass After the above monomer mixture is added dropwise, the system is heated and stirred at 75 ° C. for 2 hours. Polymerization (first stage polymerization) was performed to prepare resin particles. This resin particle is referred to as “resin particle A1”. The “resin particle A1” produced by the first stage polymerization had a weight average molecular weight of 16,500.

(B) Second-stage polymerization A monomer mixed solution composed of the following compounds was charged into a flask equipped with a stirrer, and then paraffin wax “HNP-57 (manufactured by Nippon Wax Co., Ltd.)” 93 as a release agent. .8 parts by mass was added and dissolved by heating to 90 ° C. In this way, a monomer solution was prepared.

Styrene 101.1 parts by weight n-butyl acrylate 62.2 parts by weight Methacrylic acid 12.3 parts by weight n-octyl mercaptan 1.75 parts by weight On the other hand, 3 parts by weight of the anionic surfactant is dissolved in 1560 parts by weight of ion-exchanged water. An aqueous surfactant solution was prepared and heated to 98 ° C. A mechanical system having a circulation path after adding 32.8 parts by mass (in terms of solid content) of the “resin particles A1” to the surfactant aqueous solution and further adding the monomer solution containing the paraffin wax. It was mixed and dispersed for 8 hours with a disperser “CLEAMIX (M Technique Co., Ltd.)”. An emulsified particle dispersion containing emulsified particles having a dispersed particle size of 340 nm was prepared by the mixing and dispersing.

  Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate is dissolved in 200 parts by mass of ion-exchanged water is added to the emulsified particle dispersion, and the system is polymerized by heating and stirring at 98 ° C. for 12 hours. (Second stage polymerization) was performed to prepare resin particles. This resin particle is referred to as “resin particle A2”. The “resin particle A2” produced by the second stage polymerization had a weight average molecular weight of 23,000.

(C) Third-stage polymerization A polymerization initiator solution in which 5.45 parts by mass of potassium persulfate is dissolved in 220 parts by mass of ion-exchanged water is added to the “resin particles A2” obtained by the second-stage polymerization. Under a temperature condition of 80 ° C., a monomer mixed solution composed of the following compounds was added dropwise over 1 hour.

Styrene 293.8 parts by mass n-butyl acrylate 154.1 parts by mass n-octyl mercaptan 7.08 parts by mass After completion of the dropwise addition, the mixture was heated and stirred for 2 hours to perform polymerization (third stage polymerization). It cooled to 28 degreeC and produced "resin particle 1 for core parts." Prepared by third stage polymerization. The “core part resin particles 1” had a weight average molecular weight of 26,800.

(3) Production of “resin particles for shell” Polymerization was carried out in the same manner except that the monomer mixture used in the first stage polymerization in the production of “resin particles for core 1” was changed to the following. Reaction and post-reaction treatment were performed to produce “shell resin particles 1”.

Styrene 624 parts by mass 2-ethylhexyl acrylate 120 parts by mass Methacrylic acid 56 parts by mass n-octyl mercaptan 16.4 parts by mass 2-2. Preparation of “Magenta Toner 1-7” [Preparation of “Magenta Toner 1”]
(1) Formation of core particles In a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device,
420.7 parts by mass of “core resin fine particle 1” dispersion (converted to solid content)
900 parts by mass of ion-exchanged water “Magenta Colorant Dispersion 1” 200 parts by mass was added and stirred. After adjusting the temperature in the container to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8-11.

  Next, an aqueous solution obtained by dissolving 2 parts by mass of magnesium chloride hexahydrate in 1000 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was raised and the system was heated to 65 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Beckman Coulter), and when the volume-based median diameter (D50) became 5.5 μm, sodium chloride 40. An aqueous solution obtained by dissolving 2 parts by mass in 1000 parts by mass of ion-exchanged water was added to stop the particle size growth. Further, as a ripening treatment, the fusion was continued by heating and stirring at a liquid temperature of 70 ° C. for 1 hour to form “core particles 1”. When the circularity of the obtained “core particle 1” was measured by “FPIA2100 (manufactured by Systex)”, the average circularity was 0.912.

(2) Formation of Shell Layer Next, 96 parts by mass (in terms of solid content) of dispersion of “shell resin fine particles 1” is added at 65 ° C., and 2 parts by mass of magnesium chloride hexahydrate is added to 1000 parts by mass of ion-exchanged water. The aqueous solution dissolved in the part was added over 10 minutes. After the addition, the temperature is raised to 70 ° C. (shelling temperature), stirring is continued for 1 hour, and “shell resin fine particles 1” are fused to the surface of “core particles 1” and then aged at 75 ° C. for 20 minutes. Processing was performed to form a shell layer.

  Here, 40.2 parts by mass of sodium chloride was added, cooled to 30 ° C. under conditions of 6 ° C./min, the produced colored particles were filtered, washed repeatedly with ion-exchanged water at 45 ° C., and then heated to 40 ° C. By drying with warm air, “magenta toner 1” having a shell layer formed on the surface of the core particles was obtained.

[Preparation of “Magenta Toner 2-7”]
“Magenta toners 2-7” were prepared in the same procedure except that “magenta colorant dispersion liquid 1” used in the preparation of “magenta toner 1” was changed to “magenta colorant dispersion liquids 2-7”.

3. Preparation of “Cyan Toner 1 to 4” (1) Preparation of “Cyan Colorant Dispersion Liquids 1 to 4” The following coloring was carried out in a solution in which 11.5 parts by mass of sodium n-dodecyl sulfate was dissolved in 160 parts by mass of ion-exchanged water. The agent and coloring aid Cu complex compound were gradually added. That is,
Cyan colorant 3 22.5 parts by mass The above color assistant (3-16) Cu complex compound 12.5 parts by mass Next, a stirrer “Clearmix W Motion CLM-0.8” (manufactured by M Technique Co., Ltd.) was used. Then, a “cyan colorant dispersion 1” was prepared.

(2) Preparation of “Cyan Colorant Dispersion 2 to 4” “Cyan Colorant 1” 28.0 instead of the colorant and coloring aid Cu complex compound used in the preparation of “Cyan Colorant Dispersion 1” “Cyan colorant dispersion liquid 2” was prepared in the same procedure except that parts by mass were used. In addition, “cyan coloring” was performed in the same procedure except that 28.0 parts by weight of “cyan coloring agent 2” was used in place of the coloring agent and coloring aid Cu complex compound used in the preparation of “cyan coloring agent dispersion 1”. Agent dispersion 3 ”was prepared. Further, the same procedure except that 25.1 parts by mass of “CI Pigment Blue 15: 3” was used in place of the colorant and coloring aid Cu complex compound used in the preparation of “Cyan Colorant Dispersion 1”. “Cyan colorant dispersion 4” was prepared according to the procedure.

(3) Preparation of “Cyan Toners 1 to 4” The same applies except that “Magenta Colorant Dispersion 1” was changed to “Cyan Colorant Dispersions 1 to 4” in the preparation of “Magenta Toner 1”. “Cyan toners 1 to 4” were prepared according to the procedure.

4). Preparation of “Yellow Toner 1” and “Black Toner 1” (1) Preparation of “Yellow Colorant Dispersion 1” In a solution in which 11.5 parts by mass of sodium n-dodecyl sulfate was dissolved in 160 parts by mass of ion-exchanged water. The yellow colorant described above was gradually added as follows.

C. I. Pigment Yellow 74 22.5 parts by mass Next, “Yellow Colorant Dispersion 1” was prepared by carrying out a dispersion treatment using a stirrer “Claremix W Motion CLM-0.8” (manufactured by M Technique). .

  Further, “Black Colorant Dispersion 1” was prepared in the same procedure except that “Carbon Black: Mogal L” which is a black colorant was used instead of the yellow colorant used in the preparation of “Yellow Colorant Dispersion 1”. Was prepared.

(2) Production of “Yellow Toner 1” and “Black Toner 1” In the production of “Magenta Toner 1”, the “Magenta Colorant Dispersion 1” is replaced with “Yellow Colorant Dispersion 1” and “Black Colorant”. “Yellow toner 1” and “black toner 1” were prepared in the same procedure except that the dispersion liquid 1 was changed.

5. Evaluation Experiment (1) Preparation of Developer To “magenta toners 1 to 7”, a ferrite carrier having a volume average particle size of 50 μm coated with a silicone resin is mixed so that the toner concentration becomes 6% by mass. “Magenta developers 1 to 7” as component developers were prepared. Similarly, for “cyan toners 1 to 4”, “yellow toner 1” and “black toner 1”, the ferrite carrier is mixed in the above-described procedure, and “cyan developer 1 to 4” which is a two-component developer. “Yellow developer 1” and “Black developer 1” were prepared.

(2) Evaluation Experiment Seven types of full-color developers by combining “magenta developers 1 to 7”, “cyan developers 1 to 4”, “yellow developer 1” and “black developer 1” as follows: A set was prepared. Here, four types of developer sets using “magenta developers 1 to 4” are referred to as “Examples 1-4”, and three types of developer sets using “magenta developers 5 to 7” are referred to as “comparative examples”. 1-3 ". The combinations of developers are as shown below. That is,
Example 1
-Magenta developer 1 / cyan developer 1 / yellow developer 1 / black developer 1
(Example 2)
-Magenta developer 2 / Cyan developer 1 / Yellow developer 1 / Black developer 1
(Example 3)
-Magenta developer 3 / Cyan developer 2 / Yellow developer 1 / Black developer 1
Example 4
-Magenta developer 4 / Cyan developer 3 / Yellow developer 1 / Black developer 1
(Comparative Example 1)
-Magenta developer 5 / cyan developer 4 / yellow developer 1 / black developer 1
(Comparative Example 2)
-Magenta developer 6 / cyan developer 4 / yellow developer 1 / black developer 1
(Comparative Example 3)
-Magenta developer 7 / Cyan developer 4 / Yellow developer 1 / Black developer 1
Evaluation was made by modifying a commercially available composite printer “bizhub Pro C500 (manufactured by Konica Minolta Business Technologies Co., Ltd.)” corresponding to the two-component development type image forming apparatus of FIG. I was able to put on. The evaluation machine was loaded with a developing device loaded with each developer.

Using the developer described above, in an environment of temperature 20 ° C. and humidity 50% RH, yellow single color (Y), magenta single color (M), cyan single color (C), red (R), blue (B), green ( Each solid image (2 cm × 2 cm) of G) was formed. Among the formed solid images, the lightness L ^* , color gamut a ^* , b ^* , saturation C ^* , and hue angle h of a solid magenta solid image and a blue solid image were measured by the above-described methods.

  Further, after the solid image was formed, as a blue color tone reproducibility evaluation experiment, the color tone evaluation of a blue logo mark and the color tone reproducibility of a blue-violet color code were evaluated.

<Color tone evaluation of blue logo mark>
The logos of 50 manufacturers that use the blue logo are displayed on the computer display detailed below from each company's website, and printed on the transfer paper “Washi Copy Daio” (made by Ozu Sangyo). . Based on the following criteria, the company's logo mark color on the display is reproduced on the transfer paper without a sense of incongruity based on the following criteria: Evaluation was performed based on the number of people who evaluated “Yes”, and ◎ to Δ were regarded as acceptable.

(Evaluation criteria)
◎: 90 or more people evaluated as “reproduced” (excellent)
○: 80 or more and less than 90 people (good) evaluated as “reproduced”
Δ: 60 or more and less than 80 people evaluated as “reproduced” (practical)
×: Less than 60 people evaluated as “reproduced” (bad)
(Computer display condition)
・ Computer: iMAC (Apple Computer Co., Ltd.)
・ 24-inch wide screen liquid crystal display screen ・ Screen resolution: 1920 × 1200 pixels ・ 2.16 GHz Intel Core 2 Duo processor 1
・ 4MB shared L2 cache ・ 1GB memory (2 × 512MB SO-DIMM)
・ 250GB serial ATA hard drive 2
・ 8x double layer SuperDrive (DVD + R DL, DVD ± RW, CD-RW)
・ NVIDIA GeForce 7300 GT 128MB GDDR3 memory ・ AirMac Extreme and Bluetooth 2.0 built-in ・ Apple Remote
<Evaluation of color reproducibility of blue-violet color code>
Seven blue-purple color code patch images are output on the computer display to produce printed matter corresponding to the patch images. It was determined what color the color tone of the produced printed matter could be identified.

The seven blue-purple color codes used in the evaluation are # 7f00ff, # 7700ef, # 7000e0, # 6800d1, # 6000c1, # 5900b2, and # 5100a3. It was. That is,
(Evaluation criteria)
◎; 7 colors could be identified (excellent)
○: 5 or more and less than 7 colors could be identified (good)
X: Only less than 4 colors could be identified (defect)
The results are shown in Table 1.

  As shown in Table 1, “Examples 1 to 4” satisfying the configuration of the present invention obtained good results in both the color tone evaluation of the blue logo mark and the color tone evaluation of the blue-violet color code printed matter. On the other hand, in “Comparative Examples 1 to 3” not satisfying the configuration of the present invention, the color tone did not pass. In this way, it was confirmed that there was a significant difference in the color tone of the toner image produced when the configuration of the present invention was satisfied and when it was not satisfied.

1 is a schematic diagram illustrating an example of a tandem full-color image forming apparatus capable of two-component development type image formation.

Explanation of symbols

1 (1Y, 1M, 1C, 1K) Photoconductor 2 (2Y, 2M, 2C, 2K) Charging unit 3 (3Y, 3M, 3C, 3K) Exposure unit 4 (4Y, 4M, 4C, 4K) Developing unit 5 ( 5Y, 5M, 5C, 5K, 5A) Transfer roll 6 (6Y, 6M, 6C, 6K) Cleaning device 7 Intermediate transfer unit 10 (10Y, 10M, 10C, 10K) Image forming unit 24 Heat roll fixing device 70 Intermediate Transcript

Claims (3)

In a full-color image forming method of forming a full-color image using a plurality of toners containing at least a binder resin and a colorant,
Lightness ^{L *} of 40 to 60 by ^L * ^a * ^{b *} color system measured the toner image formed only by the magenta toner, the chromaticity ^{a *} is 60 or more, the chromaticity ^{b *} is 0-80 A full color image forming method. The full color image forming method according to claim 1, wherein the chromaticity a ^* is 60 or more and 100 or less. The full-color image forming method according to claim 1, wherein a cyan toner having at least one cyan colorant represented by the following general formula (1) or general formula (2) is used.

[Wherein R ₁ represents an organic group, and the organic group may be a hetero group. ]

[Wherein R ₂ represents a hydrogen atom or an organic group. ]

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