JP2007334110A - Full-color toner for electrostatic image development and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a full-color toner for electrostatic image development which provides stable full-color images over a long period of time and ensures low-temperature fixability and hot storage resistance by controlling the charging characteristics of a color toner and a black toner. <P>SOLUTION: The full-color toner for electrostatic image development comprises a color toner obtained by coating surfaces of core particles containing at least a hydrophobic resin and one or more colorants selected from yellow, magenta and cyan colorants with a hydrophilic resin, and a black toner obtained by coating surfaces of core particles containing at least hydrophilic resin particles and a black colorant with hydrophilic resin particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a full-color toner for developing electrostatic images used in electrophotography.

As color copying machines become faster and faster, the electrophotographic industry demands stable development over a long period of time to achieve low-temperature fixing and high-resolution images in order to reduce power consumption.
Conventionally, a toner having a core / shell structure has been studied as a low-temperature fixing technique. (For example, refer to Patent Document 1) Although the core-shell structure toner can secure low-temperature fixing performance and heat-resistant storage stability, it is still insufficient for obtaining a stable full-color image over a long period of time.

  As a factor of this, generally, when a color image with a large amount of development of color toner such as a photographic image is output continuously over a long period of time, the amount of consumption of color toner increases. The toner chargeability rises due to mixing with the carrier in the developing device. When the toner charge rises worse, the toner charge amount drops, developability deteriorates, and image defects such as a decrease in image density are caused during continuous printing.

  On the other hand, black toner at the time of photographic image output is less consumed than color toner, so the amount of replenishment in the developing unit at one time is small, and the problem of charge rise is not considered important, but development by initial excessive charging is performed. On the contrary, the deterioration of the property occurs, resulting in a fluctuation in the image density.

With conventional toners, when a full-color image is output over a long period of time, it has been difficult to obtain an image with a low temperature fixability and a stable development density over a long period of time.
JP 2002-116574 A

  Accordingly, an object of the present invention is to provide a full-color toner for developing an electrostatic charge image that can obtain a stable full-color image over a long period of time by controlling the charging characteristics of the color toner and the black toner, and also ensures low-temperature fixability and heat-resistant storage stability. It is in providing the manufacturing method of.

  The above object of the present invention is achieved by the following configurations.

  1. A color toner in which the surface of a core particle containing at least a hydrophobic resin and one or more colorants selected from yellow, magenta, and cyan is coated with a hydrophilic resin, and a core containing at least hydrophilic resin particles and a black colorant A full-color toner for developing an electrostatic charge image, comprising a black toner in which hydrophilic resin particles are coated on the surface of the particles.

  2. A color toner in which a hydrophilic resin is oriented on the surface of aggregated particles obtained by aggregating and fusing at least a hydrophobic resin, a hydrophilic resin, and one or more colorants selected from yellow, magenta, and cyan; and at least hydrophilic Production of a full-color toner for developing electrostatic images, comprising a black toner obtained by adhering and fusing hydrophilic resin particles on the surface of core particles obtained by agglomerating and fusing resin particles and a black colorant Method.

  The method for producing a full-color toner for developing electrostatic images according to the present invention can provide a stable full-color image over a long period of time by controlling the charging characteristics of the color toner and black toner, and can ensure low-temperature fixability and heat-resistant storage stability. Has an excellent effect.

  The present inventors have studied a method for producing a toner that ensures low-temperature fixability and storage stability and has excellent developability.

  First, in a color toner containing one or more colorants selected from yellow, magenta, and cyan, even when the amount of color toner consumption is large, a study is made to improve the rise of the charge amount, and the inside of the toner (core Part) is made of a hydrophobic resin having a charge leakage action, so that it is possible to obtain a color toner that suppresses the diffusion of charges into the toner and has a good rise in charge.

On the other hand, in the case of black toner containing a black colorant, even when the amount of consumption is small, as a countermeasure against deterioration in developability due to excessive initial charging, the inside of the toner (core part) is contrary to color toner. By using a hydrophilic resin having a charge leakage action, it was possible to obtain a black toner in which charges are diffused into the toner and an excessive increase in charge amount is suppressed.
Here, the hydrophilic resin is a resin containing an acid monomer (polymerizable monomer) in the resin component constituting the resin, and the hydrophobic resin is an acid monomer (polymerized in the resin component constituting the resin). It is a resin that does not contain a functional monomer).

  The acid monomer has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and 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, allyl sulfosuccinic acid, 2-acrylamido-2-acrylic acid phosphooxypropyl methacrylate and the like.

  As monomers constituting the resin other than the acid monomer, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene , P-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, p- Styrene or styrene derivatives such as n-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate , Stearyl methacrylate, methacrylate Methacrylic acid ester derivatives such as lauryl phosphate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, vinyl methyl ether, vinyl ethyl ether, etc. Vinyl ethers, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, 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 acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

  As addition amount (composition ratio) of the acid monomer in hydrophilic resin, 0.5-10.0 mass% is preferable, More preferably, it is 1.0-6.0 mass%. Moreover, as hydrophilic resin, it is preferable to use combining 2 or more types of resin from which the composition ratio of an acid monomer differs. Since hydrophilic resins with different acid monomer ratios are used to coat a hydrophobic resin with a low glass transition temperature with two or more hydrophilic resins, it is possible to coat a hydrophobic resin with low heat resistance to 80% or more. This is because it can.

  The ratio of the hydrophilic resin in the toner particles is preferably 3 to 80% by mass.

  The Tg of the hydrophilic resin used in the present invention is preferably higher than the Tg of the hydrophobic resin. Specifically, the Tg of the hydrophilic resin is preferably 3 to 25 ° C. higher than the Tg of the hydrophobic resin.

  The hydrophobic resin is a resin that does not contain an acid monomer (polymerizable monomer) in the composition component constituting the resin. Specifically, all the resins formed from polymerizable monomers not containing an acid monomer among the constituent components of the hydrophilic resin are applicable. The combination of the hydrophilic resin and the hydrophobic resin is not particularly limited as a polymerizable monomer constituting each resin.

(Toner manufacturing method)
Specifically, toner particle production methods include core particle production methods such as grinding method, suspension polymerization method, emulsion polymerization method, emulsion polymerization / aggregation method, miniemulsion polymerization / aggregation method, dispersion polymerization method, dissolution suspension method, etc. Examples of the shelling method include a seed polymerization method, a resin particle adhesion / fusion ripening method, and the like.

As a color toner, in particular, a production method including a step of aggregating resin particles having at least a hydrophilic resin and a hydrophobic resin produced by a miniemulsion polymerization method to produce agglomerated particles, and fusing and aging the agglomerated particles Is preferred. (This will be referred to as the one-stage aggregation core-shell method)
As a black toner, a manufacturing method including a step of attaching a hydrophilic resin particle to the surface of a core particle obtained by aggregating and fusing a hydrophilic resin particle and a black colorant produced by a mini-emulsion polymerization method to form a shell. Is preferred. (This will be referred to as the two-stage agglomerated core-shell method)
An example of a color toner manufacturing method will be described in detail.
(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radically polymerizable monomer (2) Polymerization step (3) for preparing a dispersion of resin particles having a hydrophilic resin and a hydrophobic resin Aggregation step of aggregating resin particles and colorant particles in an aqueous medium to obtain aggregated particles (4) The aggregated aggregated particles are fused and aged by thermal energy, and the hydrophilic resin is hydrophobically applied to the surface of the toner base. (5) Cooling step for cooling the toner base dispersion liquid (6) Cooling step for cooling the toner base dispersion liquid (7) Drying step for drying the washed toner base (8) External additive to the dried toner base To add It may be included.

  Hereinafter, each step will be described.

[Dissolution / dispersion process]
This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

[Polymerization process]
In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to an aqueous medium containing a surfactant, and mechanical energy is applied to form droplets. Then, the polymerization reaction is allowed to proceed in the droplets by radicals from the water-soluble radical polymerization initiator. In addition, you may add the resin particle as a core particle in the said aqueous medium.

  By this polymerization step, resin particles having a release agent, a hydrophilic resin, and a hydrophobic resin are obtained. Such resin particles may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using uncolored resin particles, the dispersion of the colorant particles is added to the dispersion of the resin particles in the fusion and aging process described later, and the resin particles and the colorant particles are melted. By attaching it, it can be made a toner base.

[Aggregation process]
Add salting-out agent made of alkali metal salt or alkaline earth metal salt as a coagulant with a critical coagulation concentration or higher to form coagulated particles in water containing resin particles and, if necessary, colorant particles. . In the aggregation step, resin particles and colorant particles can be aggregated together with release agent particles, internal additive particles such as charge control agents, and the like. As for the addition timing of internal additive particles such as resin particles, colorant particles, release agent particles and charge control agents, all particles should be added by the time when the aggregate particle size becomes about half of the final particle size. Is preferred.

[Fusion and aging process]
The fusion / aging is preferably performed by thermal energy (heating).

  Specifically, the particles agglomerated in the aggregating step are heated and stirred to fluidize at the resin molecule level in the particles, and the hydrophilic resin that is easily compatible with water as the medium is moved to the particle surface, and water is added. The hydrophobic resin that repels and moves to the inside of the particles and is oriented to the hydrophobic resin core / hydrophilic resin shell to form a toner base having a core-shell structure.

  As a condition for forming a hydrophobic resin core / hydrophilic resin shell, it is necessary to fluidize the resin at a molecular weight level, so that the heating temperature is 30 ° C. or more higher than the highest glass transition temperature (maxTg) of the resin. The temperature is preferable, and (maxTg) + 40 ° C. or more is more preferable. However, when an aqueous medium containing water is used, the upper limit is made less than 100 ° C. from the boiling point of water. The heating time is inversely proportional to the heating temperature and needs about 30 minutes to 5 hours, but it is preferable that the heating time be sufficiently fluidized for 2 hours or more. Furthermore, as the stirring conditions, it is preferable that the agglomerated particles are not easily united with each other and the temperature distribution is uniform, and therefore, the shape of the stirring blade is a Max Blend blade or a full zone blade. preferable.

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

[Washing process]
In this washing step, the toner base is solid-liquid separated from the dispersion of the toner base that has been cooled to a predetermined temperature in the above-described step, and the solid-liquid separated toner cake (the toner base in a wet state is aggregated into a cake form). And a cleaning treatment for removing deposits such as surfactants and salting-out agents. Here, the washing treatment method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a washing method using a filter press or the like.

[Drying process]
In this step, the washed toner cake is dried to obtain a dried toner base. 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 base is preferably 5% by mass or less, more preferably 2% by mass or less.

  In addition, when the toner bases subjected to the drying treatment are aggregated due to 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.

[External process]
This step is a step in which an external additive is mixed with the dried toner base as necessary to produce a toner.

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

  Next, an example of a black toner manufacturing method will be described in detail.

The toner according to the present invention is produced, for example, through the following steps.
(1) Dissolution / dispersion step for dissolving or dispersing a release agent in a radical polymerizable monomer (2) Polymerization step for preparing a dispersion of fine resin particles having a hydrophilic resin (3) Resin in an aqueous medium Aggregation and fusion step for aggregating and fusing fine particles and colorant particles to obtain core particles (association particles) (4) First aging step for adjusting the shape by aging associated particles with thermal energy (5) Core Shelling step in which resin particles for shell are added to a particle (associate particle) dispersion to aggregate and fuse the shell particles on the surface of the core particles to form colored particles having a core / shell structure (6) Core A second aging step for adjusting the shape of the core-shell structured colored particles by aging the colored particles having a shell structure with thermal energy (7) Solid-liquid separation of the colored particles from the cooled colored particle dispersion, Surfactant etc. from the colored particles Drying process for drying the washing step (8) washing the treated colored particles removed by hand, after the drying process if necessary,
(9) There may be a step of adding an external additive to the dried colored particles. The above process will be described in detail later.

  When producing the black toner according to the present invention, first, resin particles and colorant particles are associated and fused to produce colored particles (hereinafter referred to as core particles) that become cores. Next, resin particles are added to the core particle dispersion, and the resin particles are aggregated and fused on the surface of the core particles to coat the surface of the core particles to produce colored particles having a core / shell structure. As described above, the toner according to the present invention is a toner having a core-shell structure in which resin particles are added to a dispersion of core particles prepared by various manufacturing methods and fused to the core particles. .

"Dissolution / dispersion process"
This is the same as the color toner manufacturing method described above.

[Polymerization process]
In the description of the color toner manufacturing method described above, the procedure is the same except that the acid monomer is always included as a raw material for the resin particles.

[Aggregation / fusion process] (including the first aging process)
As the aggregation and fusion method in the fusion step, a salting out / fusion method using resin fine particles (colored or non-colored resin fine particles) obtained in the polymerization step is preferable. In the agglomeration / fusion step, the internal additive fine particles such as the release agent fine particles and the charge control agent can be agglomerated and fused together with the resin fine particles and the colorant fine particles.

  The “aqueous medium” in the agglomeration / fusion step is one in which the main component (50% by mass or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  The colorant fine particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. Examples thereof include a medium type disperser. Examples of the surfactant used include the same surfactants as those described above. The colorant (fine particles) may be surface-modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the molecular weight solution, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting out / fusing method, which is a preferred agglomeration and fusing method, is a salting out method comprising an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like in water in which resin fine particles and colorant fine particles are present. An agent is added as a coagulant having a critical coagulation concentration or higher, and then salting-out proceeds by heating to a temperature above the glass transition point of the resin fine particles and above the melting peak temperature (° C.) of the mixture. At the same time, it is a process of fusing. Here, the alkali metal salt and 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 agglomeration and fusion are performed by salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible.

  The reason for this is not clear, but there are problems that the aggregation state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. appear. The temperature for adding the salting-out agent needs to be at least the glass transition temperature of the 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 resin fine particles, the salting out / fusion of the resin fine particles proceeds rapidly, but the particle size cannot be controlled. There arises a problem that particles having a 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 not higher than the glass transition temperature of the resin fine particles, and then the temperature is raised as quickly as possible to a temperature not lower than the glass transition temperature of the resin fine particles and not lower than the melting peak temperature (° C.) of the mixture. Heat to. 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 this fusing step, a dispersion of associated particles (core particles) formed by salting out / fusing resin fine particles and arbitrary fine particles is obtained.

And in this invention, it controls so that the formed core particle may have an uneven | corrugated shape by controlling the heating temperature of the aggregation / fusion process and the heating temperature and time of the first aging process.
Specifically, the heating temperature is lowered in the agglomeration / fusion process to suppress the progress of fusion between the resin particles to promote deforming, the heating temperature is lowered in the first aging process, and Shorten the time to control the core particles to be uneven.

[Shelling process] (Including second aging process)
In the shelling step, the resin particle dispersion for the shell is added to the core particle dispersion to agglomerate and fuse the resin particles for the shell onto the surface of the core particles, and the resin particles for the shell are coated on the surface of the core particles. To form colored particles.

  Specifically, the core particle dispersion is added with a dispersion of resin particles for shells while maintaining the temperature in the above-described aggregation / fusion process and the first aging process, and it takes several hours while continuing heating and stirring. Then, the resin particles for shell are slowly coated on the surface of the core particles to form colored particles. The heating and stirring time is preferably 1 hour to 7 hours, particularly preferably 3 hours to 5 hours. Then, when the colored particles have reached a predetermined particle size by shelling, a terminator such as sodium chloride is added to stop particle growth, and then the resin particles for the shell adhered to the core particles are fused. Continue to stir for several hours. In the shelling step, a shell having a thickness of 10 to 500 nm is formed on the core particle surface. In this way, resin particles are fixed to the surface of the core particles to form a shell, and colored particles having a uniform shape are formed.

  In the present invention, it is possible to produce a rounded toner having a uniform shape through the above-described steps. Moreover, it is possible to control the shape of the colored particles in the true sphere direction by setting the time of the second aging step longer or by setting the aging temperature higher.

  [Cooling step] The subsequent steps are the same as the color toner manufacturing method described above.

  Hereinafter, the material constituting the toner according to the present invention will be described. However, the explanation regarding the resin is omitted because it has been described above.

(Initiator)
The polymerizable monomer can be polymerized using a radical polymerization initiator. In the suspension polymerization method, an oil-soluble polymerization initiator can be used. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based 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) propane, tris- (t- Examples thereof include peroxide polymerization initiators such as butylperoxy) triazine and polymer initiators having a peroxide in the side chain.

  In the case of using an emulsion polymerization / aggregation method, a water-soluble radical polymerization initiator can be used. As the water-soluble polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like can be used.

(Chain transfer agent)
In order to adjust the molecular weight of the resin, a commonly used chain transfer agent can be used. The chain transfer agent used is not particularly limited. For example, mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, and mercaptopropionate esters such as n-octyl-3-mercaptopropionate. , Terpinolene, carbon tetrabromide and α-methylstyrene dimer are used.

(Coloring agent)
As the colorant used in the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

  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.

  These colorants may be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

(Release agent)
A known compound can be used as the release agent 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 diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate, etc. And amide waxes such as ethylenediamine behenyl amide and trimellitic acid tristearyl amide.

  The amount of the release agent contained in the toner is preferably 1 to 20% by mass and more preferably 3 to 15% by mass with respect to the whole toner.

(Charge control agent)
A charge control agent can be added to the toner according to 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 organic fine particles that can be used as an external additive include spherical fine particles having a number average primary particle size 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.

<Developer>
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 μm to 0.5 μm of magnetic particles in the toner can be used. be able to.

  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.

  The particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The coating resin is not particularly limited, and for example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, or the like is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to. Among these, a coat carrier coated with a styrene-acrylic resin is more preferable because it can prevent the external additive from being detached and ensure durability.

<Image formation>
The toner of the present invention can be suitably used particularly for an image forming apparatus for fixing a transfer material on which a toner image is formed in a contact heating type fixing apparatus.

  Preferred examples of the contact heating method include a heat pressure fixing method, a heat roll fixing method, and a pressure heating fixing method in which fixing is performed by a rotating pressure member including a fixedly arranged heating body.

<Transfer material>
The transfer material used in the present invention is a support for holding a toner image, and is usually called an image support, a recording material, or transfer paper. Specifically, various transfer materials such as plain paper and fine paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, cloth, etc. However, it is not limited to these.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.

Fabrication of color toner matrix (one-stage aggregation core-shell method)
(Preparation of Resin Particle A) Preparation of Two-layered Resin Particle First Stage Polymerization Styrene 248 g
117 g of n-butyl acrylate
n-Octyl mercaptan 1.5g
Polyethylene wax (melting point 80 ° C) 190.0g
The mixed solution consisting of was put in a stainless steel kettle equipped with a stirrer, heated to 70 ° C. and dissolved to prepare a monomer mixed solution.

  On the other hand, a surfactant solution in which 2 g of polyoxyethylene (2) sodium dodecyl ether sulfate is dissolved in 1350 g of ion-exchanged water is heated to 70 ° C., added to and mixed with the monomer mixed solution, and then a mechanical type having a circulation path. Dispersion was performed at 70 ° C. for 30 minutes using a disperser “Clearmix” (manufactured by M Technique) to prepare an emulsified dispersion.

  Next, an initiator solution in which 7.5 g of potassium persulfate was dissolved in 150 g of ion-exchanged water was added to this dispersion, and this system was heated and stirred at 78 ° C. for 1.5 hours to perform polymerization. Particles were obtained.

Second-stage polymerization To the resin particles obtained above, an initiator solution in which 12 g of potassium persulfate is dissolved in 220 g of ion-exchanged water is added, and under a temperature condition of 80 ° C.,
Styrene 435g
n-Butyl acrylate 132g
Methacrylic acid 33g
n-octyl mercaptan 8.0 g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain “resin particles A”.

(Production of Resin Particles B to E) Production of Two-layer Structure Resin Particles The composition ratio of the polymerizable monomer used in the production of “resin particle A” was changed as shown in Table 1, and “resin particles B” to “Resin particles E” were produced.

<Preparation of Y colorant dispersion>
90 g of sodium dodecyl sulfate was dissolved in 1600 g of ion-exchanged water with stirring. While stirring this solution, 420 g of Y colorant (CI Pig. Y74) was gradually added, and then dispersed using a stirrer “CLEAMIX” (manufactured by M Technique). A dispersion of colorant particles was prepared. This is referred to as a “colorant dispersion”. The particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

<Preparation of Toner Base Y-1>
(Aggregation process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 300 g of “resin particles A”, 1400 g of ion-exchanged water, 120 g of “colorant dispersion”, polyoxyethylene (2) A solution prepared by dissolving 3 g of sodium dodecyl ether sulfate in 120 g of ion-exchanged water was added and the liquid temperature was adjusted to 30 ° C., and then a 5 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 10. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C.

When the median diameter (D ₅₀ ) on the volume basis reached 6.0 μm, an aqueous solution in which 150 g of sodium chloride was dissolved in 600 g of ion-exchanged water was added to stop particle growth.

(Fusion and aging process)
After stopping the particle growth, as a fusing and aging process, the mixture is heated and stirred at a liquid temperature of 98 ° C. for 2 hours, so that the fusing between the particles proceeds at the same time and the hydrophilic resin is applied to the particle surface. Then, the hydrophobic resin was localized in the interior to produce core / shell structured particles. Stirring was performed using a stirrer having a Fluson blade so that a laminar flow state was obtained.

  Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing and drying process)
The particles produced in the aging step were subjected to solid-liquid separation with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a toner base wet cake. The wet cake was washed with water using the basket-type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). % Of the toner was dried to prepare “toner base Y-1”.

<Preparation of Toner Bases Y-2 to Y-5>
Toner bases Y-2 to Y to 5 were prepared in the same manner except that the resin particles A used in the aggregation step in the preparation method of toner base Y-1 were changed to the resins shown in Table 2.

<Preparation of Toner Base M-1 to 5 and C-1 to 5>
In the production of the toner bases Y-1 to Y-5, the toner bases M-1 to M-5 are similarly prepared except that the colorant dispersion used in the aggregation process is changed to the M colorant (CI Pigment Red 122). Toner bases C-1 to 5 were prepared in the same manner except that the colorant was changed to C colorant (CI Pigment Blue 15; 3).

Preparation of black toner base (two-stage aggregation core / shell method)
Production of resin particles for core (Production of resin particles F) Production of single-layer resin particles Styrene 248 g
117 g of n-butyl acrylate
n-Octyl mercaptan 1.5g
Polyethylene wax (melting point 80 ° C) 190.0g
The mixed solution consisting of was put in a stainless steel kettle equipped with a stirrer, heated to 70 ° C. and dissolved to prepare a monomer solution.

  On the other hand, a surfactant solution obtained by dissolving 2 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 1350 g of ion-exchanged water is heated to 70 ° C., added to and mixed with the monomer solution, and then mechanically dispersed having a circulation path. Dispersion was carried out at 70 ° C. for 30 minutes using a machine “Clearmix” (manufactured by M Technique) to prepare an emulsified dispersion.

  Next, an initiator solution in which 7.5 g of potassium persulfate was dissolved in 150 g of ion-exchanged water was added to this dispersion, and this system was heated and stirred at 78 ° C. for 1.5 hours to perform polymerization. Resin particles F "were obtained.

(Preparation of Resin Particles G to H) Preparation of Single Layer Structure Resin Particles The composition ratio of the polymerizable monomers used in the preparation of “resin particles F” was changed as shown in Table 1, and “resin particles G” to “Resin particles H” were produced.

Preparation of Resin Particles for Shell (Preparation of Resin Particles I) Preparation of Single-Layered Resin Particles A reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introducing device is charged with 8 g of sodium dodecyl sulfate and 3000 g of ion exchange water The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was carried out by stirring to prepare resin particles. This is referred to as “resin particle G”.

544 g of styrene
176 g of n-butyl acrylate
Methacrylic acid 80g
n-octyl mercaptan 5.5 g
(Preparation of Resin Particle J) Preparation of Single-Layer Structure Resin Particles “Resin Particle J” was prepared by changing the composition ratio of the polymerizable monomers used in the preparation of “Resin Particle I” as shown in Table 1. .

<Preparation of colorant dispersion>
90 g of sodium dodecyl sulfate was dissolved in 1600 g of ion-exchanged water with stirring. While stirring this solution, 420 g of carbon black “Regal 330R” (manufactured by Cabot Corp.) is gradually added, and then dispersed by using a stirrer “Claremix” (manufactured by M Technique Co., Ltd.). A dispersion of agent particles was prepared. This is referred to as a “colorant dispersion”. The particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

(Preparation of toner base Bk-1)
(First aggregation and fusion (core part formation) process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, 300 g of “resin particles G”, 1400 g of ion-exchanged water, 120 g of “colorant dispersion 1”, polyoxygen, A solution prepared by dissolving 3 g of ethylene (2) sodium dodecyl ether sulfate in 120 g of ion-exchanged water was added, the liquid temperature was adjusted to 30 ° C., and then the pH was adjusted to 10 by adding a 5 mol / L aqueous sodium hydroxide solution. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C.

In this state, the particle size of the aggregated particles was measured with “Coulter Multisizer 3” (manufactured by Beckman Coulter), and when the median diameter (D ₅₀ ) on the volume basis became 5.0 μm, sodium chloride 40 An aqueous solution in which 2 g is dissolved in 1000 g of ion-exchanged water is added to stop the growth of the particles. Further, as a fusing treatment, the fusing is continued by heating and stirring at a liquid temperature of 98 ° C. for 6 hours. A core part having a median diameter (D ₅₀ ) of 5.0 μm was prepared. For stirring, a stirrer having a Fluson blade was used.

(Second aggregation and fusion (shell layer formation) process)
100 g of “resin particle I” was added to the solution in which the core part was formed, and heating and stirring were continued for 3 hours to aggregate and fuse the “resin particle I” on the surface of the core part particle. Here, an aqueous solution in which 40.2 g of sodium chloride was dissolved in 1000 g of ion-exchanged water was added, the mixture was cooled at 8 ° C./min, hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing and drying process)
The particles produced in the above process were subjected to solid-liquid separation with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a toner base wet cake. The wet cake was washed with water using the basket-type centrifuge until the electric conductivity of the filtrate reached 5 μS / cm, and then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). % To dryness to produce “toner base Bk-1”.

(Preparation of toner base Bk-2 to 3)
The toner base Bk is similarly used except that the resin particles used in the first and second aggregation / fusion processes used in the aggregation step in the method for preparing the toner base Bk-1 are changed to the resin particles shown in Table 2. Preparation of −2 to Bk to 3 was performed.

(External additives mixed in toner base)
The “toner bases Y-1 to Y-5”, “toner bases M-1 to M-5”, “toner bases C-1 to C-5” and “toner bases Bk-1 to Bk-3” obtained above. 1% by mass of hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity = 68) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm, degree of hydrophobicity = 63) , "Henschel mixer" (manufactured by Mitsui Miike Chemical Co., Ltd.) and mixed with "Toner Y-1 to Y-5", "Toner M-1 to M-5", "Toner C-1 to C-5" and "Toner Bk". -1 to Bk-3 ".

<< Preparation of developer >>
Each toner obtained above was mixed with a ferrite carrier having a volume median diameter (D ₅₀ ) of 50 μm coated with a silicone resin to prepare each developer having a toner concentration of 6 mass%.

<Evaluation>
The following items were evaluated for the toner prepared above. The print image was obtained using a commercially available multifunction machine “bizhub PRO C500” (manufactured by Konica Minolta Business Technologies, Inc.) adopting an electrophotographic system. In the evaluation of the low-temperature fixability, the fuser was modified so that the fixing temperature could be changed.

  The evaluation was carried out for the following items in an environment of 20 ° C. and 55% RH in which the respective color toners shown in Table 3 were sequentially loaded into the evaluation apparatus (Examples 1 to 5 and Comparative Examples 1 to 3).

The print is an A4 image with a pixel rate of 10% (a character image is 7%, a human face photo, a solid white image, an original image with a solid image of each color toner of 5 mm square is divided into ¼ equal parts) 100,000 sheets of fine paper (64 g / m ² ) were used.

  In the evaluation, ◎ to ○ were acceptable with no problems, and x were unacceptable with problems.

(Visual evaluation)
<Heat resistant storage>
As the evaluation of heat-resistant storage property, Y, M, C, and Bk toners were respectively evaluated.
However, since the evaluation results for the Y, M, and C toners were the same, Table 4 shows the results as color evaluation items.

  The measurement method is as follows: 0.5 g of toner is placed in a 10 ml glass bottle with an inner diameter of 21 mm, the lid is closed, shaken 600 times at room temperature with a tap denser KYT-2000 (manufactured by Seishin Enterprise), and the lid is removed at 55 ° C. And left in an environment of 35% RH for 2 hours. Next, the toner is placed on a 48 mesh (aperture 350 μm) sieve, taking care not to break up the toner aggregates, set in a powder tester (manufactured by Hosokawa Micron), and fixed with a press bar and knob nut. After adjusting the vibration strength to a feed width of 1 mm and applying vibration for 10 seconds, the ratio (mass%) of the amount of toner remaining on the sieve was measured.

  The toner aggregation rate is a value calculated by the following formula.

(Toner aggregation rate (%)) = (Mass of residual toner on sieve (g)) / 0.5 (g) × 100
The heat resistant storage stability of the toner was evaluated according to the criteria described below.

A: The toner aggregation rate is less than 15% by mass (the toner has excellent heat-resistant storage stability)
○: Toner aggregation rate of 20% by mass or less (good heat storage stability of toner)
X: Toner aggregation rate exceeds 20% (toner has poor heat storage stability and cannot be used)
(Low temperature fixability)
The fixing temperature can be evaluated in an environment of normal temperature and normal humidity (20 ° C., 50% RH), and the surface temperature of the heating roller (measured at the center of the roller) of the image evaluation device in increments of 5 ° C. from 100 ° C. to 200 ° C. Changed to produce a fixed image. As the transfer material, A4 quality paper (65 g / m ² ) was used.

  As an evaluation method, an image in which the fixing temperature was changed at the start of printing was taken, and the following evaluation was performed for each solid image.

  However, since the evaluation results for the Y, M, and C toners were the same, Table 4 shows the results as color evaluation items.

For fixing temperature, the fixing strength of the obtained fixed image is determined using a method according to the mending tape peeling method described in Chapter 9 Section 1.4 of “Basics and Applications of Electrophotographic Technology: Electrophotographic Society”. Asked. Specifically, after changing the surface temperature of the transfer material to produce a solid fixed image of 5 mm square with a toner adhesion amount of 0.6 mg / cm ² for all colors, “Scotch Mending Tape” (manufactured by Sumitomo 3M) ) Was measured before and after peeling, and the residual ratio of the image density was determined as the fixing rate.

Tape peeling method 1) Measure absolute reflection density D ₀ of 5 mm square solid image part 2) Lightly stick “Mending tape” (Sumitomo 3M Co., Ltd. No.810-3-12 equivalent) 3) 1 kPa The tape is rubbed back and forth 3.5 times with pressure. 4) The tape is peeled off with an angle of 180 ° and a force of 200 g. 5) The absolute reflection density D ₁ after peeling is measured. 6) Fixing rate = 100 × D ₁ / D ₀ ( %)
A fixing temperature at which a fixing rate of 90% or more was obtained was evaluated as a fixing possible temperature. For the measurement of the image density, a reflection densitometer “RD-918” (manufactured by Macbeth) was used.

Evaluation criteria A: Minimum fixing temperature of 140 ° C. or lower ○: Minimum fixing temperature of 140 ° C. to lower than 160 ° C. ×: Minimum fixing temperature of 160 ° C. or higher (image stability)
The stability of the image was evaluated by the image density of the solid image portion of each color toner on the 50,000th and 100,000th sheets at the start. The image density was measured with a reflection densitometer RD-918 manufactured by Macbeth. The image density is an absolute density.

A: Each density of the solid image portion of Bk and Y, M, C is 1.2 or more (good)
○: Each density of Bk and solid image portions of Y, M, and C is 0.8 or more (no problem in practical use)
×: Each density of Bk and solid image portions of Y, M, and C is less than 0.8. However, since the evaluation results for Y, M, and C toners were the same, Table 4 shows the color evaluation items. The results are listed.

  It turns out that the Example of this invention is excellent compared with a comparative example.

Claims (2)

A color toner in which the surface of a core particle containing at least a hydrophobic resin and one or more colorants selected from yellow, magenta, and cyan is coated with a hydrophilic resin, and a core containing at least hydrophilic resin particles and a black colorant A full-color toner for developing an electrostatic charge image, comprising a black toner in which hydrophilic resin particles are coated on the surface of the particles. A color toner in which a hydrophilic resin is oriented on the surface of aggregated particles obtained by aggregating and fusing at least a hydrophobic resin, a hydrophilic resin, and one or more colorants selected from yellow, magenta, and cyan; and at least hydrophilic Production of a full-color toner for developing electrostatic images, comprising a black toner obtained by adhering and fusing hydrophilic resin particles on the surface of core particles obtained by agglomerating and fusing resin particles and a black colorant Method.