JP2008268565A - Toner for electrostatic charge image development and method for manufacturing the toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner for electrostatic charge image development achieving both of low temperature fixability and heat-resistant storage property, showing preferable rising of charges in repeated use and less environmental dependence of output image density, and to provide a toner for electrostatic charge image development manufactured by the above method. <P>SOLUTION: The method for manufacturing a toner for electrostatic charge image development is characterized in that, after core particles are produced by aggregating resin particles with a metal salt, resin particles for a shell are deposited on the core particles without adding a metal salt to form a shell to obtain a core-shell structure toner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toner for developing an electrostatic image and a method for producing the same.

  As energy saving progresses, in the electrophotographic technology, in recent years, the energy of the fixing device has been reduced (low-temperature fixing) in order to reduce power consumption and high-speed printing. However, the thermal stability of the toner has decreased with the low-temperature fixing, and the heat-resistant storage stability during storage and transportation has not been sufficiently improved.

  On the other hand, since components such as a colorant and a release agent are exposed from the toner surface, it has been insufficient to maintain stable chargeability for a long period of time. In order to solve these problems, a technique for improving toner performance with a so-called core-shell structure having a structure in which the toner surface is coated with a resin has been proposed (see, for example, Patent Documents 1 and 2).

  In addition, in order to provide a high-quality image for a long period of time in a toner, it is also required to reduce the stability of charging rise, the difference in charging environment, and the stability of charge amount during repeated use.

  In the emulsion association type toner, resin particles made of a polymerizable monomer and particles of toner constituent materials such as a colorant are aggregated and fused using, for example, a metal salt as an aggregating agent. In particular, the resin particles are made of aggregated particles (colored particles) obtained through an aggregation / fusion process for associating with each other, and the amount of the flocculant added in the aggregation / fusion process is large. In the case where is composed of a polymerizable monomer containing a polar group such as a carboxylic acid group, the metal salt derived from the coagulant adhering to or encapsulating the obtained associated particles can be easily removed by washing treatment. Is difficult.

  However, since the metal salt derived from the flocculant used in the aggregation / fusion process has high hygroscopicity, the resulting emulsion-associative toner has high hygroscopicity. As a result, when image formation is performed under high temperature and high humidity, the chargeability is lower than when image formation is performed under low temperature and low humidity. Therefore, when an emulsion association type toner is used as the toner, troubles are likely to occur in the environmental dependency of image density, the rise of charge, and the like.

  In such an emulsion-associative toner, when a core / shell structure is formed, it is important to coat the core surface with resin particles constituting the shell layer without using an aggregating agent.

In consideration of the influence of such a metal salt, a technique is disclosed in which the content of a divalent or trivalent metal element and the content of a polyvalent metal element are defined (for example, see Patent Documents 3 and 4).
JP 2004-191618 A JP 2004-271638 A JP 2002-287410 A JP 2003-330227 A

  An object of the present invention is a method for producing a toner for developing an electrostatic charge image that has both low-temperature fixability and heat-resistant storage stability, good charge rise upon repeated use, and less environmental dependency of output image density And an electrostatic image developing toner produced by the production method.

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

  1. After agglomerating resin particles with a metal salt to produce core particles, a shell resin particle is adhered to the core particles without adding a metal salt to form a shell, thereby obtaining a core-shell structure toner. A method for producing a toner for developing an electrostatic charge image.

  2. 2. The method for producing a toner for developing an electrostatic charge image according to 1 above, wherein the adhesion of the shell resin particles onto the core particles is performed by adjusting the pH of the shell resin particle dispersion.

  3. 3. The method for producing a toner for developing an electrostatic charge image according to 1 or 2 above, wherein the resin particles for shell are resin particles composed of a copolymer of a vinyl polymerizable monomer.

  4). 4. The static electricity according to any one of 1 to 3, wherein the core-shell toner includes a vinyl copolymer resin obtained by polymerization from a polymerizable monomer containing a polyvalent carboxylic acid component. A method for producing a toner for developing a charge image.

  5. An electrostatic image developing toner produced by the method for producing an electrostatic image developing toner according to any one of 1 to 4 above.

  6). 6. The toner for developing an electrostatic charge image according to 5 above, having a glass transition point of 30 to 45 ° C.

  According to the present invention, there is provided a toner for developing an electrostatic charge image that has both low-temperature fixability and heat-resistant storage stability, has good charge rise upon repeated use, and has less environmental dependency of the output image density, and It was possible to provide a method for producing a toner for developing an electrostatic image.

  Hereinafter, the present invention will be described in detail.

  The present invention provides a method for producing a toner for developing an electrostatic charge image having a core / shell structure (also simply referred to as a toner) by aggregating resin particles with a metal salt to produce core particles, and then forming a metal on the core particles. Without further addition of salt, the resin particles are adhered to form a shell to obtain a core / shell structure toner.

  The metal salt adhering to the toner surface or the metal salt encapsulated in the toner has a high hygroscopic property, and the presence of this metal salt increases the hygroscopic property of the toner itself, resulting in a difference in charging characteristics depending on the environment. Therefore, by reducing this amount, it is possible to improve the charge rising of the toner and reduce the environmental difference in the charge amount. In particular, in an emulsion-association type toner, the toner is obtained through an aggregation / fusion process in which a metal salt is aggregated and melted using an aggregating agent, and the influence of the metal salt as described above is large. .

  However, in the core / shell toner manufacturing method, this metal salt is not used at all, and even in the core / shell toner formed by adjusting the pH of the ionic surfactant, the shell resin particle dispersion, heating, etc. The problem remained. This is presumably because the particle size distribution of the toner particles becomes broad with the non-uniform cohesion force on the resin particles, and as a result, the charge amount distribution of the toner particles becomes broad.

  Therefore, the present inventor is most effective in reducing the amount of metal salt adhering to the shell on the surface of the toner while improving the rise in charge of the toner and reducing the environmental difference in charge amount, while the core particles are used as the toner. In order to maintain the charge amount distribution sharply, it is considered that agglomeration with a metal salt is necessary, and the present invention has been achieved.

  The present inventor has disclosed an emulsion-associative toner having a core / shell structure, in which resin particles are aggregated with a metal salt to produce core particles, and then a shell resin is added without further adding a metal salt onto the core particles. By forming a shell by attaching particles to form a core-shell toner, it is possible to reduce the environmental difference between the charge rise and the charge amount.

  Next, a method for producing the toner for developing an electrostatic charge image of the present invention will be described.

  The toner of the present invention is produced, for example, through the following steps.

(1) Dissolution / dispersion step for dissolving or dispersing the release agent in the radical polymerizable monomer (2) Polymerization step for preparing a dispersion of resin particles (3) Resin particles and colorant particles in an aqueous medium Agglomeration and fusion step for agglomerating and fusing the particles to obtain core particles (associate particles) (4) first aging step for adjusting the shape by aging the core particles with thermal energy (5) in the core particle dispersion Shell forming step of adding resin particles for shell and adhering and fusing the particles for shell on the surface of the core particles to form colored particles of core / shell structure (6) Thermal energy of colored particles of core / shell structure (2) The colored particles are solid-liquid separated from the cooled colored particle dispersion, and a surfactant or the like is removed from the colored particles. Cleaning process to remove (8) Cleaning process A drying step of drying the treated colored particles In addition, there may be a step of (9) adding an external additive to the dried colored particles after the drying step, if necessary.

  The above process will be described in detail later.

  When the toner of the present invention is produced, first, resin particles and colorant particles are associated and fused to produce core particles (hereinafter referred to as core particles). 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. The above shows an example in which the mini-emulsion method is used as a method for producing resin particles, but in the present invention, resin particles used in various production methods such as emulsion polymerization, suspension polymerization, and dissolution suspension method are used as methods for producing resin particles. Can be used. However, the particle size of the resin particles is preferably several hundred nm.

  Hereinafter, each manufacturing process of the toner of the present invention will be described.

(1) Dissolution / Dispersion Step This step is a step of preparing a radical polymerizable monomer solution in which a release agent is dissolved in a radical polymerizable monomer and a release agent is mixed.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which a wax is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less is added. Then, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to advance the polymerization reaction in the droplets. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

  By this polymerization step, resin particles containing a wax (release agent) and a binder resin are obtained. Such resin particles may be colored fine particles or non-colored fine particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. When uncolored resin particles are used, the dispersion of the colorant particles is added to the dispersion of resin particles in the aggregation / fusion process described later, and the resin particles and the colorant particles are fused. By making it, it can be set as colored particles.

(3) Aggregation / fusion process As a method of aggregation and fusion in the fusion process, a salting out / fusion method using resin particles (colored or non-colored resin particles) obtained in the polymerization process 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 particles and the colorant particles.

  The term “salting out / fusion” here refers to agglomeration and fusion being performed in parallel, and when the particles have grown to a desired particle size, an aggregation terminator is added to stop the particle growth, and further if necessary. This means that heating for controlling the particle shape is continued.

  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, and examples include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  Colorant particles can be prepared by dispersing a 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. Moreover, as a surfactant used, the same thing as the above-mentioned surfactant can be mentioned. 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 dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is filtered off, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting-out / fusion method, which is a preferred agglomeration and fusion 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 particles and colorant particles are present. When an agent is added as a coagulant having a critical coagulation concentration or higher, and then the salting-out proceeds by heating to a temperature above the glass transition point of the resin particles and above the melting peak temperature (° C.) of the mixture. This is a process of fusing at the same time.

  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 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 is a problem that the aggregation state of the particles varies depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner varies. appear. The temperature for adding the salting-out agent needs to be at least the glass transition temperature of the resin 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 particles, the salting-out / fusion of the resin 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 particles, and thereafter, the temperature is raised as quickly as possible to a temperature not lower than the glass transition temperature of the resin particles and not lower than the melting peak temperature (° C.) of the mixture. Heat. 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 fusion step, a dispersion of associated particles (core particles) formed by salting out / fusion of resin particles and arbitrary fine particles is obtained.

(4) First aging step And, in the present invention, by controlling the heating temperature of the coagulation / fusion step and particularly the heating temperature and time of the first aging step, the particle size is constant and the distribution is narrow. The core particle surface is controlled so as to have a smooth but uniform shape. Specifically, the heating temperature is lowered in the aggregation / fusion process to suppress the progress of fusion between the resin particles to promote homogenization, the heating temperature is lowered in the first aging process, and the time is increased. The length of the core particles is controlled to be a uniform shape by increasing the length.

(5) Shelling step In this step, a shell was formed by adhering and fusing onto the surface of the core particle by adjusting the pH of the resin particle dispersion for shell to 3 to 8 without adding a flocculant. This is a step of forming colored particles having a core-shell structure.

  By making the pH of the resin particle dispersion for shell layer formation higher than the original pH, orienting the carboxyl groups in the resin particles on the surface, the shell resin particles are prevented from aggregating with each other, The resin particles for shells, which are micron, are adhered to the surface of the core particle by the influence of the metal salt used for the aggregation of the core particle and the physical adhesion force utilizing the particle size difference.

  Further, by forming a shell layer using resin particles whose pH is adjusted to 3 to 8, the surface of the toner having a core / shell structure can have a large number of polar groups, thereby improving the charging performance of the toner. Stabilization can be achieved.

  Specifically, the resin particles for the shell whose pH is adjusted to 3 to 8 are added into the core particle dispersion after the aggregation / fusion step and the first aging step, and the stirring is continued. Then, the resin particles for shell are slowly coated on the core particle surface over several hours to form colored particles. The heating and stirring time is preferably 1 to 7 hours, particularly preferably 1 to 3 hours.

(6) Second ripening step At the stage where the colored particles have reached a predetermined particle size by shelling, a terminator such as sodium chloride is added to stop particle growth, and thereafter the shell is attached to the core particles. In order to fuse the resin particles, heating and stirring are continued for several hours. In the shelling step, a shell having a thickness of 100 to 300 nm is formed on the surface of the core particle. In this way, resin particles are fixed to the surface of the core particles to form a shell, and rounded and colored particles having a uniform shape are formed.

  In the present invention, 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.

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

  In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the colored particles from the dispersion of colored particles cooled to a predetermined temperature in the above-described step, and a solid-liquid separated toner cake (in a wet state) A cleaning treatment for removing deposits such as a surfactant and a salting-out agent from an aggregate obtained by agglomerating certain colored particles into a cake is performed. 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 cake to obtain dried 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 water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less.

  In addition, when the dried colored particles are aggregated with a weak interparticle attractive force, 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 This step is a step of preparing a toner by mixing the dried colored particles with an external additive as necessary. As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  The mass average particle diameter (dispersed particle diameter) of the composite resin particles is preferably in the range of 10 to 1000 nm, more preferably in the range of 30 to 300 nm. The mass average particle diameter is a value measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  First, the metal salt used in the present invention will be described.

(Metal salt)
Metal salts include monovalent metals such as alkali metal salts such as sodium, potassium and lithium, divalent metals such as typical metal elements such as beryllium and magnesium, alkaline earth such as calcium, strontium, barium and radium. Examples thereof include salts of similar metals, divalent metal salts such as manganese and copper, and trivalent metal salts such as iron and aluminum.

  Among these metal salts, specific examples of the monovalent metal salt include sodium chloride, potassium chloride, lithium chloride and the like. Examples of the metal salt of the divalent metal include magnesium chloride, calcium chloride, calcium nitrate, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate and the like. Examples of the trivalent metal salt include aluminum chloride and iron chloride. These are appropriately selected according to the purpose and used in the toner production process. Further, polyaluminum chloride, polyaluminum hydroxide and the like can be used as appropriate.

  Among these, a metal salt having a valence of 2 or more, preferably reducing the addition amount, among these.

  These flocculants are preferably added in an amount equal to or higher than the critical aggregation concentration. The critical flocculation concentration is an index relating to the stability of the aqueous dispersion, and indicates a concentration at which flocculation occurs when a flocculant is added. This critical aggregation concentration varies greatly depending on the emulsified components and the dispersant itself. For example, it is described in Seizo Okamura et al., “Polymer Chemistry 17, 601 (1960) edited by Japan Society of Polymer Science”, and the like, and a detailed critical aggregation concentration can be obtained. As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ (zeta) potential of the dispersion is measured, and the salt concentration at which this value changes is defined as the critical aggregation concentration. You can ask for it.

  The addition amount of the flocculant according to the present invention may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration.

(Core shell toner)
The core-shell toner in the present invention does not necessarily have to completely cover the core particle surface. It only needs to be coated to such an extent that it has an effect.

  As shown in FIG. 1A, by covering the surface of the core particle with an area ratio of 70% or more, preferably 80% or more, it is possible to achieve both low temperature fixability and heat resistant storage stability during storage. . Further, as shown in FIG. 1B, a part of the shell layer may enter the core portion. 1 (a) and 1 (b), the same effects as those obtained by covering the entire surface of the core particle with a shell layer as shown in FIG. 1 (c) are exhibited.

  The toner of the present invention preferably has a shell thickness of 10 to 500 nm, more preferably 100 to 300 nm.

(Tg)
The glass transition point of the toner of the present invention is preferably 30 to 45 ° C. for heat aggregation and low temperature fixability.

  The glass transition point of the toner of the present invention can be determined using a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer) or a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer). As a measurement procedure, 4.5 to 5.0 mg of toner is precisely weighed to two decimal places, enclosed in an aluminum pan (KITNO.0219-0041), and set in a DSC-7 sample holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis was performed based on heat data.

  The glass transition point draws an extension of the baseline before the rise of the first endothermic peak and a tangent line indicating the maximum slope between the rise portion of the first peak and the peak apex, and the intersection is the glass transition point. As shown.

[Toner material used in the present invention]
(1) Binder Resin The resin that forms the core part and the resin that forms the shell layer are preferably styrene-acrylic copolymer resins. Moreover, the monomer which produces resin which forms a core part includes a polymerizable monomer that lowers the glass transition temperature (Tg) of a copolymer such as propyl acrylate, propyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate. Copolymerization is preferred. Moreover, the monomer for producing the resin forming the shell layer is copolymerized with a polymerizable monomer that raises the glass transition temperature (Tg) of a copolymer such as styrene, methyl methacrylate, and methacrylic acid. Is preferred.

  The resin constituting the toner of the present invention will be described in more detail.

  As the resin used for each of the core and shell structures of the toner of the present invention, a polymer obtained by polymerizing a polymerizable monomer as described below can be used.

  The resin according to the present invention contains a polymer obtained by polymerizing at least one polymerizable monomer as a constituent component. Examples of the polymerizable monomer include styrene, o-methylstyrene, m -Methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, styrene or styrene derivatives such as pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, N-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, methacrylate Methacrylic acid ester derivatives such as n-octyl phosphate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, acrylic Acrylate derivatives such as isopropyl acid, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, Olefins such as ethylene, propylene and isobutylene, halogenated vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride and vinylidene fluoride, vinyl propionate, vinyl acetate, Vinyl esters such as vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole, N-vinyl indole, N-vinyl There are N-vinyl compounds such as pyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers can be used alone or in combination.

  Moreover, it is preferable to use combining the thing which has an ionic dissociation group as a polymerizable monomer which comprises resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Further, as the polymerizable monomer constituting the resin, those having an ionic dissociation group as described above are preferably used in combination, but polyvalent carboxylic acids are particularly preferable as those having an ionic dissociation group. Specific examples thereof include dicarboxylic acids such as itaconic acid and maleic acid, and itaconic acid is particularly preferable. By introducing the polyvalent carboxylic acid, hydrogen bonds due to carboxyl groups are generated inside the toner, the toner resin elasticity is enhanced, offset separation is improved, and low-temperature fixability is improved.

  Furthermore, polyfunctionality such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

(2) Colorant As the colorant used in the toner of the present invention, carbon black, a magnetic material, a dye, a pigment and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal Black, lamp black, etc. are 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, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum and manganese-copper-tin, chromium dioxide, and the like can be used.

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures thereof can also be used.

  Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 93, 94, 138, 156, 158, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. The number average primary particle diameter varies depending on the type, but is preferably about 10 to 200 nm.

  As a method for adding a colorant, the resin particles are added at the stage of agglomeration by adding an aggregating agent, and the polymer is colored. The colorant can be used by treating the surface with a coupling agent or the like.

(3) Wax (release agent)
Examples of the wax that can be used in the toner of the present invention include conventionally known waxes. Specifically, polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, and trimethylolpropane. Tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellit Ester waxes such as acid tristearyl and distearyl maleate, ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. Such as amide waxes.

  The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the wax content in the toner is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass.

  The polymerization initiator, chain transfer agent, and surfactant that can be used in the toner production method will be described.

(4) Radical polymerization initiator usable in the present invention The resin constituting the core and shell constituting the toner of the present invention is produced by polymerizing the aforementioned polymerizable monomer, but can be used in the present invention. Examples of the radical polymerization initiator include the following.

  Specifically, as the oil-soluble polymerization initiator, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane- 1-carbonitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide , Diisopropylperoxycarbonate, 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, Squirrels include the like (t-butylperoxy) peroxide polymerization initiator or a peroxide polymer initiator having a side chain, such as triazines.

  Moreover, when forming resin particles by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

  Generally used chain transfer agents can be used for the purpose of adjusting the molecular weight of the resin constituting the composite resin particles. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, n-octyl-3-mercaptopropionic acid ester, terpinolene, carbon tetrabromide and α-methyl. Styrene dimer or the like is used.

(5) Dispersion stabilizer Further, a dispersion stabilizer can be used in order to appropriately disperse the polymerizable monomer and the like in the reaction system. Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Furthermore, generally used surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

  The surfactant used in the present invention will be described.

  In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, 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. can be mentioned.

(Developer)
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner of the present invention is used as a two-component developer, the carrier is made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. Magnetic particles can be used, and ferrite particles are particularly preferable.

  Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used. The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins.

  Moreover, it does not specifically limit as binder resin which comprises a binder type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used. .

  FIG. 2 is a schematic view showing an example of an image forming apparatus according to the present invention.

  As shown in FIG. 2, the image forming apparatus 1 is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 9Y, 9M, 9C, and 9K, a belt-like intermediate transfer member 6, and a paper feed. And a toner cartridge 5Y, 5M, 5C, and 5K, the fixing device 10 according to the present invention, an operation unit 91, and the like.

  An image forming unit 9Y that forms a yellow image includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a transfer unit 7Y, and a cleaning unit 8Y arranged around an image carrier (hereinafter referred to as a photoreceptor) 1Y. Have The image forming unit 9M that forms a magenta image includes a photoreceptor 1M, a charging unit 2M, an exposure unit 3M, a developing device 4M, a transfer unit 7M, and a cleaning unit 8M. The image forming unit 9C that forms a cyan image includes a photoreceptor 1C, a charging unit 2C, an exposure unit 3C, a developing device 4C, a transfer unit 7C, and a cleaning unit 8C. The image forming unit 9K that forms a black image includes a photoreceptor 1K, a charging unit 2K, an exposure unit 3K, a developing device 4K, a transfer unit 7K, and a cleaning unit 8K.

  The intermediate transfer body 6 is wound around a plurality of rollers 6A, 6B, and 6C and is rotatably supported.

  Each color image formed by the image forming units 9Y, 9M, 9C, and 9K is sequentially primary-transferred onto the rotating intermediate transfer body 6 by the transfer means 7Y, 7M, 7C, and 7K, and the combined color image. Is formed.

  The paper P stored in the paper feed cassette 20 as the paper feed means is fed one by one by the paper feed roller 21, is conveyed to the transfer means 7 A through the registration roller 22, and the color image is transferred onto the paper P. Is secondarily transferred.

  The paper P on which the color image has been transferred is fixed by the fixing device 10, passes through the transport rollers 23 and 24, which are transport means, and is sandwiched by the paper discharge rollers 25 and placed on the paper discharge tray 26 outside the apparatus. The

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these embodiments.

(Preparation of resin particle A1 dispersion for core)
(1) First Stage Polymerization In a flask equipped with a stirrer, a monomer composition comprising 265 g of styrene, 110 g of n-butyl acrylate, 27 g of methacrylic acid, and 5 g of n-octyl mercaptan was added with paraffin wax “ 135 g of “HNP-57” (manufactured by Nippon Seiwa Co., Ltd.) was added, and the mixture was heated to 85 ° C. and dissolved to prepare a monomer solution [1-1].

  On the other hand, a surfactant solution in which 3 g of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) is dissolved in 1100 g of ion-exchanged water is heated to 90 ° C. The above-mentioned monomer solution [1-1] is mixed and dispersed for 4 hours by “Cleamix” (manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 600 nm. Dispersion of resin particles by adding an aqueous initiator solution in which 11.5 g of a polymerization initiator (KPS) is dissolved in 200 g of ion-exchanged water, and heating and stirring the system at 85 ° C. for 2 hours. A liquid [a1] was prepared.

(2) Second-stage polymerization: Formation of outer layer To the above resin particle dispersion [a1], an initiator aqueous solution in which 11.5 g of a polymerization initiator (KPS) is dissolved in 200 g of ion-exchanged water is added, Under temperature conditions
Styrene 480g
165 g of n-butyl acrylate
n-octyl mercaptan 10g
A monomer solution [1-2] consisting of 1 was added dropwise over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 3 hours, followed by cooling to 28 ° C. to obtain a resin particle dispersion [A1] with composite resin particles having a two-layer structure.

  The glass transition temperature (Tg) of the composite resin particles constituting this resin particle dispersion [A1] was 35 ° C.

(Preparation of core resin particle A2 dispersion)
(1) First-stage polymerization In a flask equipped with a stirrer, a monomer composition composed of 275 g of styrene, 94 g of n-butyl acrylate, 26 g of methacrylic acid, and 5 g of n-octyl mercaptan was added as paraffin wax “ HNP-57 ”(manufactured by Nippon Seiwa Co., Ltd.) (103 g) was added, and the mixture was heated to 85 ° C. and dissolved to prepare a monomer solution [2-1].

  On the other hand, a surfactant solution in which 2.5 g of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) was dissolved in 1100 g of ion-exchanged water was heated to 90 ° C., and mechanical dispersion having a circulation path The monomer solution [2-1] is mixed and dispersed for 3 hours by a machine “Clearmix” (manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 750 nm. An initiator aqueous solution in which 11.5 g of a polymerization initiator (KPS) is dissolved in 200 g of ion-exchanged water is added to the liquid, and this system is polymerized by heating and stirring at 85 ° C. for 2 hours to obtain a resin. A particle dispersion [a2] was prepared.

(2) Second-stage polymerization: formation of outer layer To the above resin particle dispersion [a2], an initiator aqueous solution in which 11.5 g of a polymerization initiator (KPS) is dissolved in 200 g of ion-exchanged water is added, Under temperature conditions
Styrene 503g
142g of n-butyl acrylate
n-octyl mercaptan 10g
A monomer solution [2-2] consisting of 1 was added dropwise over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 3 hours, followed by cooling to 28 ° C. to obtain a resin particle dispersion [A2] composed of composite resin particles having a two-layer structure.

  The glass transition temperature (Tg) of the composite resin particles constituting the resin particle dispersion [A2] was 43 ° C.

(Preparation of resin particle A3 dispersion for core)
(1) In a flask equipped with a first stage polymerization stirrer, a monomer composition comprising 242 g of styrene, 125 g of n-butyl acrylate, 27 g of methacrylic acid, and 5 g of n-octyl mercaptan was added as a release agent with a paraffin wax “ A monomer solution [3-1] was prepared by adding 150 g of “HNP-57” (manufactured by Nippon Seiwa Co., Ltd.) and heating to 82 ° C. for dissolution.

  On the other hand, a surfactant solution in which 3 g of an anionic surfactant (polyoxy (2) dodecyl ether sulfate sodium salt) is dissolved in 1100 g of ion-exchanged water is heated to 90 ° C. The above-mentioned monomer solution [3-1] was mixed and dispersed for 4 hours by “Cleamix” (manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 600 nm. Dispersion of resin particles by adding an aqueous initiator solution in which 11.5 g of a polymerization initiator (KPS) is dissolved in 200 g of ion-exchanged water, and heating and stirring the system at 85 ° C. for 2 hours. Liquid [a3] was prepared.

(2) Second-stage polymerization: formation of outer layer An aqueous starting solution prepared by dissolving 11.5 g of a polymerization initiator (KPS) in 200 g of ion-exchanged water is added to the above resin particle dispersion [a3], and a temperature condition of 80 ° C. Below,
Styrene 452g
194 g of n-butyl acrylate
n-octyl mercaptan 10g
A monomer solution [3-2] consisting of 1 was added dropwise over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 3 hours, followed by cooling to 28 ° C. to obtain a resin particle dispersion [A3] composed of composite resin particles having a two-layer structure.

  The glass transition temperature (Tg) of the composite resin particles constituting this resin particle dispersion [A3] was 28 ° C.

(Preparation of resin particle dispersion for shell)
A surfactant solution in which 2.0 g of an anionic surfactant (Structural Formula 1) shown below was dissolved in 3000 g of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device. The internal temperature was raised to 80 ° C. while stirring and stirring at a stirring speed of 230 rpm under a nitrogen stream. (Structural Formula 1) C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ SO ₃ Na.

  To this surfactant solution, an initiator solution prepared by dissolving 10 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water was added, 528 g of styrene, 176 g of n-butyl acrylate, 120 g of methacrylic acid, A monomer mixture composed of 22 g of n-octyl mercaptan was dropped over 3 hours, and the system was heated and stirred at 80 ° C. for 1 hour to prepare a resin particle.

  The weight average molecular weight of the resin particles was 12,000, and the glass transition temperature (Tg) was 53 ° C.

(Preparation of polyvalent carboxylic acid-containing resin particle 1 dispersion)
A surfactant solution prepared by dissolving 3.0 g of an anionic surfactant (Structural Formula 1) shown below in 2800 g of ion-exchanged water in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device. The internal temperature was raised to 80 ° C. while stirring and stirring at a stirring speed of 230 rpm under a nitrogen stream.

on the other hand,
630 g of methyl methacrylate
n-Butyl acrylate 130g
Itaconic acid 40g
n-Octyl mercaptan 28g
Were mixed and heated to 78 ° C. to dissolve itaconic acid to prepare a monomer solution.

  Next, an initiator aqueous solution in which 10 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 400 g of ion exchange water in a 5 L reaction vessel was added, and the monomer mixture was added dropwise over 2 hours. The system was heated and stirred at 80 ° C. for 2 hours to obtain a polyvalent carboxylic acid-containing resin particle 1 dispersion.

  The polyvalent carboxylic acid-containing resin particles 1 constituting this dispersion had a glass point transition temperature (Tg) of 47 ° C. and a molecular weight of 10,000.

(Preparation of polyvalent carboxylic acid-containing resin particle 2 dispersion)
The same procedure as in the preparation of the polyvalent carboxylic acid-containing resin particle island resin particle 1 dispersion, except that the type and composition ratio of the monomers constituting the monomer solution and the molecular weight modifier were changed as shown below. Thus, a dispersion liquid of polyvalent carboxylic acid-containing resin particles 2 was obtained.

  The resin particles had a glass transition temperature (Tg) of 52 ° C. and a molecular weight of 12,000.

80g of styrene
Methyl methacrylate 530g
n-Butyl acrylate 130g
56g maleic acid
n-octyl mercaptan 22g
(Preparation of Colorant Particle Dispersion 1)
C. A solution prepared by dissolving 60 parts of sodium dodecyl sulfate in 1800 parts of ion-exchanged water with stirring was mixed with C.I. I. 200 parts of Pigment Blue 15: 3 was gradually added, and then dispersed using a stirrer “CLEARMIX” (manufactured by M Technique Co., Ltd.) to obtain Colorant Particle Dispersion Liquid 1. As a result of measuring the particle diameter of the colorant in the colorant dispersion [1] using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average diameter was 210 nm.

(Preparation of Colorant Particle Dispersion 2)
Nonionic surfactant (manufactured by Sanyo Chemical Co., Ltd .: Nonipol 400) in a solution obtained by stirring and dissolving in 1800 parts of ion-exchanged water was stirred under a C.I. I. 200 parts of Pigment Blue 15: 3 was gradually added, and then dispersed using a stirrer “Ultra Turrax” (manufactured by IKA) to obtain Colorant Particle Dispersion Liquid 2. As a result of measuring the particle diameter of the colorant in the colorant particle dispersion 2 using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average diameter was 230 nm.

Example 1
[Production of Toner 1]
(Salting out / fusion (association / fusion) process) (core formation)
470 parts (in terms of solid content) of “core part resin particles A1”, 1900 parts of ion-exchanged water, and 223 parts of “colorant particle dispersion 1” were added to a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. Was stirred in a reaction vessel equipped with. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.5.

Next, an aqueous solution in which 80 parts of magnesium chloride hexahydrate was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the system was heated to 75 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.912.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, sodium hydroxide was added and 260 parts of the “shell layer resin particle” dispersion adjusted to pH 4.0 in advance was added at 75 ° C., and stirring was continued for 1 hour. The “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. for 1 hour, The resulting fused particles are cooled to 30 ° C. at 8 ° C./min, filtered, washed repeatedly with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles 1 having a layer were obtained.

  The circularity was measured in a water dispersion system using a flow type particle image analyzer “FPIA-2100” (manufactured by Sysmex Corporation).

  Hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity = 68) is added to the obtained toner base particles at a ratio of 1% by mass, and hydrophobic titanium oxide (number average primary particle size = 20 nm, Hydrophobic degree = 63) is added at a ratio of 1% by mass, mixed by “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.), and then coarse particles are removed using a 45 μm aperture sieve, 1 was obtained.

Example 2
[Production of Toner 2]
(Salting out / fusion (association / fusion) process) (core formation)
452 parts (solid content conversion) of “core part resin particles A1”, “polyvalent carboxylic acid-containing resin particles 1” 52 parts, ion-exchanged water 1900 parts, “colorant particle dispersion 1” 223 parts, Was stirred in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.0.

Next, an aqueous solution in which 80 parts of magnesium chloride hexahydrate was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the system was heated to 74 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.914.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, 260 parts of “resin particle for shell layer” dispersion added with sodium hydroxide and adjusted to pH 5.0 in advance was added at 75 ° C., and stirring was continued for 1 hour. Then, “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. for 1 hour, The resulting fused particles are cooled to 30 ° C. at 8 ° C./min, filtered, washed repeatedly with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles 2 having a layer were obtained. The obtained toner base particles were treated with an external additive in the same manner as in the preparation of the toner 1 to obtain a toner 2.

Example 3
[Production of Toner 3]
(Salting out / fusion (association / fusion) process) (core formation)
390 parts (in terms of solid content) of “core part resin particles A1”, “polyvalent carboxylic acid-containing resin particles 2” 260 parts, ion-exchanged water 1900 parts, “colorant particle dispersion 1” 223 parts, Was stirred in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 11.0.

Next, an aqueous solution in which 24 parts of aluminum chloride was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, temperature increase was started and the system was heated to 72 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.911.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, 260 parts of “resin particle for shell layer” dispersion added with sodium hydroxide and adjusted to pH 5.0 in advance was added at 75 ° C., and stirring was continued for 1 hour. Then, “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. for 1 hour. , Cooled to 30 ° C. under the condition of 8 ° C./min, filtered fused particles, repeatedly washed with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles 3 having a shell layer were obtained. The obtained toner base particles were treated with an external additive in the same manner as in the preparation of toner 1 to obtain toner 3.

Example 4
[Production of Toner 4]
(Salting out / fusion (association / fusion) process) (core formation)
429 parts (solid content conversion) of “core part resin particles A3”, “polyvalent carboxylic acid-containing resin particles 1” 208 parts, ion-exchanged water 1900 parts, “colorant particle dispersion 1” 223 parts, Was stirred in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.0.

Next, an aqueous solution in which 80 parts of magnesium chloride hexahydrate was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the system was heated to 74 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.915.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, 260 parts of “resin particle for shell layer” dispersion added with sodium hydroxide and adjusted to pH 5.0 in advance was added at 75 ° C., and stirring was continued for 1 hour. Then, “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. for 1 hour, The resulting fused particles are cooled to 30 ° C. at 8 ° C./min, filtered, washed repeatedly with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles 4 having a layer were obtained. The resulting toner base particles were treated with an external additive in the same manner as in the preparation of toner 1 to obtain toner 4.

Example 5
[Production of Toner 5]
(Salting out / fusion (association / fusion) process) (core formation)
416 parts (in terms of solid content) of “core part resin particles A2”, “polyvalent carboxylic acid-containing resin particles 1” 171 parts, ion-exchanged water 1900 parts, “colorant particle dispersion 1” 223 parts, Was stirred in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.5.

Next, an aqueous solution in which 80 parts of magnesium chloride hexahydrate was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the system was heated to 74 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.913.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, 260 parts of “resin particle for shell layer” dispersion added with sodium hydroxide and adjusted to pH 6.0 in advance was added at 75 ° C., and stirring was continued for 1 hour. Then, “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. for 1 hour, The resulting fused particles are cooled to 30 ° C. at 8 ° C./min, filtered, washed repeatedly with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles 5 having a layer were obtained. The obtained toner base particles were treated with an external additive in the same manner as in the preparation of toner 1 to obtain toner 5.

Comparative Example 1
[Production of Toner 6]
(Salting out / fusion (association / fusion) process) (core formation)
470 parts (in terms of solid content) of “core part resin particles A1”, 1900 parts of ion-exchanged water, and 223 parts of “colorant particle dispersion 1” were added to a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. Was stirred in a reaction vessel equipped with. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.5.

Next, an aqueous solution in which 80 parts of magnesium chloride hexahydrate was dissolved in 80 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, heating was started, and the system was heated to 75 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.912.

(Shelling operation) (Formation of shell layer)
Next, when it reached 6.0 μm, 260 parts of the “resin particles for shell layer” dispersion was added at 75 ° C., and stirring was continued for 30 minutes. Then, 80 parts of magnesium chloride hexahydrate was ion-exchanged again. An aqueous solution dissolved in 80 parts of water was added over 10 minutes with stirring. After standing for 5 minutes, the temperature was started to rise to 84 ° C. over 20 minutes. In this state, heating and stirring were continued for 2 hours, and the “shell layer resin particles” were fused to the surface of the “core part” to form a shell layer. Here, an aqueous solution obtained by dissolving 82 parts of sodium chloride in 330 parts of ion-exchanged water was added to terminate the shelling, and the fusion was continued by heating and stirring at a liquid temperature of 84 ° C. for 30 minutes, The resulting fused particles are cooled to 30 ° C. at 8 ° C./min, filtered, washed repeatedly with ion-exchanged water at 40 ° C., and then dried with hot air at 40 ° C. Toner base particles having a layer were obtained. The obtained toner base particles were treated with an external additive in the same manner as in the preparation of Toner 1 to obtain Toner 6.

Comparative Example 2
[Production of Toner 7]
(Salting out / fusion (association / fusion) process) (core formation)
470 parts (in terms of solid content) of “core part resin particles A1”, 1900 parts of ion-exchanged water, 223 parts of “colorant particle dispersion 2” and 10 g of a cation interface (manufactured by Kao Corporation: Sanizol B50) Were mixed using a homogenizer (manufactured by IKA: Ultra Turrax T50) and dispersed, and the mixture was stirred in a reaction vessel equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device. Next, the inside of the reaction vessel was heated to 48 ° C. while stirring. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Co.), and this state was maintained until the particle median system (D ₅₀ ) reached 6.0 μm. Formed. The circularity of the “core part” was 0.908.

(Shelling operation) (Formation of shell layer)
Next, when reaching 6.0 μm, 260 parts of the “resin particle for shell layer” dispersion was gently added, and the temperature was raised to 50 ° C. over 5 minutes. In this state, heating and stirring were continued for 1 hour to fuse the “shell layer resin particles” on the surface of the “core part” to form a shell layer. Thereafter, 15 g of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) was added thereto, and then the reaction vessel was sealed and heated to 105 ° C. while continuing to stir using a magnetic seal for 3 hours. Retained. Then, after cooling, the produced fused particles are filtered, washed repeatedly with ion exchange water at 40 ° C., and then dried with hot air at 40 ° C. to obtain toner base particles having a shell layer on the core surface. It was. The toner base particles thus obtained were treated with an external additive in the same manner as in the preparation of the toner 1 to obtain a toner 7.

(Preparation of developer)
For toners [1] to [7], a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin is mixed so that the concentration of the toner is 6% by mass, and developer [1] to [1] to [2] is a two-component developer. [7] was prepared.

[Evaluation]
The developer prepared above was sequentially loaded into a digital color multifunction peripheral (bizhub PRO C500) (manufactured by Konica Minolta Business Technologies), and the following items were performed in an environment of 20 ° C. and 55% RH. Print is an image with a pixel rate of 10% (original image with character image 7%, human face photo, solid white image, solid black image divided into 1/4 each) A4 quality fine paper (64 g / m ² ) Went to.

(Low temperature fixability)
The surface temperature of the heating roller of the fixing device was changed so that the paper surface temperature changed in increments of 10 ° C. within the range of 80 to 150 ° C., and the toner image was fixed at each changed temperature to produce a fixed image. In creating the print image, high-quality paper (A4 size) (80 g / m ² ) was used. The fixing strength of the printed image obtained by fixing is fixed using a method in accordance with the mending tape peeling method described in Chapter 9 Section 1.4 of “Basics and Applications of Electrophotographic Technology: Electrophotographic Society”. The rate was evaluated.

Specifically, after creating a 2.54 cm square solid black print image with a toner adhesion amount of 0.6 mg / cm ² , images before and after peeling with “Scotch Mending Tape” (manufactured by Sumitomo 3M) The density was measured, and the residual ratio of the image density was determined as the fixing ratio.

  The “transfer material (paper) surface temperature” at which the fixing rate is 95% or more is defined as the minimum fixing temperature. The surface temperature of the transfer material (paper) was measured with a non-contact thermometer. The image density was measured with a reflection densitometer “RD-918” (manufactured by Macbeth).

A: Fixing is possible at a minimum fixing temperature of less than 120 ° C. ○: Fixing is possible at a minimum fixing temperature of 120 ° C. or more and less than 140 ° C. ×: Fixing is possible at a minimum fixing temperature of 140 ° C. or more.

(Heat resistant storage)
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 then the lid is removed at 55 ° C. and 35% RH. For 2 hours. Next, place the toner on a 48-mesh (mesh 350 μm) sieve, taking care not to crush the toner aggregates, set the powder tester (manufactured by Hosokawa Micron), and fix it 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
A: The toner aggregation rate is less than 15% by mass (the toner has excellent heat-resistant storage stability)
○: The toner aggregation rate is 20% by mass or less (the toner has good heat storage stability)
X: The toner aggregation rate exceeds 20% (toner has poor heat-resistant storage property and cannot be used).

(Evaluation of rise of charge amount (presence / absence of sweep))
After copying 300,000 evaluation images, the presence or absence of streak-like image defects (the presence or absence of sweeps) was visually observed on a morning halftone image sample in a low-temperature and low-humidity environment (10 ° C., 20% RH).

A: No sweeping is observed. O: A thin streak-like mark remains, but there is no problem. X: A streak-like image defect exists.

(Environment-dependent image density)
The maximum image density of the solid image portion was measured with a Macbeth reflection densitometer. The difference in image density between a high temperature and high humidity environment (33 ° C., 80% RH) and a low temperature and low humidity environment (10 ° C., 20% RH) was measured, and the following rank evaluation was performed.

A: Image density difference is less than 0.05 B: Image density difference is 0.05 to 0.1
X: Image density difference exceeds 0.1 In the present invention, it was judged that ◎ and ○ were practical.

  From Table 2, it can be seen that the toner of the present invention is superior to the comparative toner in all evaluations.

FIG. 3 is a schematic diagram showing a structure of a toner of the present invention. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Colorant particle 2 Resin which forms core part 3 Resin which forms shell part 9Y, 9M, 9C, 9K Image forming unit 6 Intermediate transfer body 10 Fixing device 20 Paper feed cassette P Transfer material

Claims (6)

After agglomerating resin particles with a metal salt to produce core particles, a shell resin particle is adhered to the core particles without adding a metal salt to form a shell, thereby obtaining a core-shell structure toner. A method for producing a toner for developing an electrostatic charge image. 2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the adhesion of the resin particles for shells onto the core particles is performed by adjusting the pH of the resin particle dispersion for shells. 3. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the resin particles for shell are resin particles composed of a copolymer of a vinyl polymerizable monomer. The said core-shell structure toner contains the vinyl-type copolymer resin formed by superposing | polymerizing from the polymerizable monomer containing a polyhydric carboxylic acid component, The any one of Claims 1-3 characterized by the above-mentioned. A method for producing a toner for developing an electrostatic image. An electrostatic image developing toner produced by the method for producing an electrostatic image developing toner according to claim 1. The toner for developing an electrostatic charge image according to claim 5, wherein the glass transition point is 30 to 45 ° C.

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