JP2005091436A - Electrostatic latent image developing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic latent image developing toner containing toner particles having excellent stress resistance obtained by aggregating particles in a water system, or the like, and also to provide a method for manufacturing the same. <P>SOLUTION: The electrostatic latent image developing toner is obtained by depositing particles for shells on core particles prepared by aggregating particles for cores, wherein the blending ratio of the particles for cores to the particles for shells is 50:50 to 90:10, the particles for shells contain a softer resin b1 and a harder resin b2 than the particles for cores. When the weight average molecular weights of the particles for cores, the particles for shells, the resin b1 and the resin b2 are represented by MwA, MwB, Mwb1 and Mwb2, respectively, the relations MwA<MwB and Mwb1<MwA<Mwb2 hold. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrostatic latent image developing toner used in electrophotography, electrostatic photography and the like.

Due to recent advances in IT technology, digitalization of images and documents is advancing not only in office environments but also in general homes. Higher image quality, lower costs, and smaller size in electrophotographic copiers, printers, and fax machines.・ The need for energy saving is increasing.
In response to such needs, the following characteristics are particularly required for toner.

First, a toner particle size reduction is generally required for high image quality, but for a particle size reduction of 7 μm or less, the production process by the kneading and pulverization method is no longer appropriate from the viewpoint of yield. Chemical toner production processes represented by emulsion polymerization and suspension polymerization are suitable.
In addition, the one-component development method, which is a simple image forming process, is suitable for reducing the cost and size of the machine. However, in the one-component development, the mechanical force when the toner passes through the developing sleeve and the regulating portion is used. Strength against various stresses is required. However, since the main binder resin of the toner inevitably has a styrene acrylic resin composition in the chemical toner production method by the emulsion polymerization method or the suspension polymerization method described above, the polyester type resin generally used in the kneading and pulverization method is used. Compared to resin, it has the disadvantage of being weak against mechanical stress. That is, the styrene acrylic polymerized toner which is advantageous for reducing the particle size has a disadvantage that the mechanical strength is inferior to that of the polyester toner.

  To deal with such problems, efforts have been made to improve the toner resin design by combining the high molecular weight and low molecular weight molecular weight distribution of the resin. Generally, a technique of balancing the property and the fixing property. In addition, a design method is also widely known in which the toner has a core-shell structure for functional separation, the core part mainly improves low-temperature fixing performance, and the shell part improves mechanical strength and blocking resistance. Yes.

  In particular, when a core-shell structure type toner is produced by agglomerating particles in an aqueous medium, if the shell agent particles have a high molecular weight design or a molecular structure having a cross-linked structure in order to obtain mechanical strength, the shell agent becomes the core. Even if it can be adhered to the portion, there has been a problem that the fusion / film formation does not proceed well and as a result, the capsule structure is easily broken.

  Various approaches have been made so far to deal with such problems, and Patent Document 1 proposes a core-shell structured toner for the purpose of achieving both low-temperature fixability and storage stability. There are proposed methods for adhering the toner with mechanical shearing force such as mechanochemical, and methods for adhering the shell agent particles by utilizing the properties of the surfactant in the wet process and further smoothing the toner surface with a solvent. Yes. However, in the dry shelling process, the surface is not smooth, that is, the surface becomes uneven and sufficient mechanical strength cannot be obtained. Even in the step of attaching the shell agent particles in the wet process, the production method described in this document has a limitation in the material design of the shell material, and it has been difficult to exert sufficient mechanical strength.

  Further, in Patent Document 2, a core-shell structure type toner by suspension granulation with a polyester resin having excellent mechanical strength and fixing strength enables both blocking resistance and low-temperature fixing properties, and destruction of the capsule structure in the developing device. Suppression is proposed. However, in the production method described in this document, the molecular weight of the shell portion cannot be increased so much that, as a result, the filming property improvement level in the two-component development remains, and improvement with respect to the regulatory stress in the one-component development. It has not yet reached.

Further, Patent Document 3 specifies the relationship between the molecular weight of the core resin and the shell resin in the core-shell structure type toner by the emulsion polymerization association method and the production method thereof, and further uses a low molecular resin as an essential component for the shell resin. On the other hand, there is a proposal to improve the fusing property and film forming property of the shell agent. However, in the toner described in this document, the surface property of the toner is certainly homogenized with the shell resin, and the charging property can be greatly improved by suppressing the exposure of the colorant, but it is required for one-component development. The conditions for improving the mechanical strength are not satisfied and are insufficient. When the mechanical strength (stress resistance) of the toner is insufficient, a crushed toner piece is generated, and the toner is fixed to a member such as a developing roller in the developing portion, causing image noise.
JP-A-9-179336 Japanese Patent Laid-Open No. 11-7156 JP 2002-116574 A

The present invention has been made based on the above situation.
The first object of the present invention is to withstand mechanical stress at a development restricting portion in one-component development and endurance in an electrostatic latent image developing toner containing toner particles obtained by agglomerating particles in an aqueous system. The object of the present invention is to provide a toner having dramatically improved properties.
A second object of the present invention is to homogenize the surface properties of toner in a full color toner for each color and to improve the chargeability.
A third object of the present invention is to provide a toner that can be fixed at low temperature without oil and that has blocking resistance (storage stability).
A fourth object of the present invention is to provide a method for producing a toner that achieves the above object.

The present invention contains core-shell structure type toner particles obtained by adhering / fusing shell resin particles B to the surface of core particles obtained by aggregating / fusing at least core resin particles A in an aqueous medium. A toner for developing an electrostatic latent image, wherein the blending weight ratio (core: shell) of the resin particle A for the core and the resin particle B for the shell is 50:50 to 90:10, and the resin particle B for the shell is the core The resin component b1 softer than the resin particle A and the hard resin component b2 are contained as essential components, and the weight average molecular weights of the resin particle A for the core, the resin particle B for the shell, the resin component b1 and the resin component b2 are respectively MwA, The present invention relates to a toner for developing an electrostatic latent image, wherein the following relationship is established when MwB, Mwb1, and Mwb2.
MwA <MwB
Mwb1 <MwA <Mwb2

The present invention also provides
(1) A step of producing a dispersion of core resin particles A,
(2) a step of producing a dispersion of resin particles B for shell,
(3) A step of aggregating or aggregating / fusing at least the core resin particles A in an aqueous medium to form core particles;
(4) a step of adhering / fusing at least the shell resin particles B to the surface of the core particles to form a shell layer to obtain core-shell structured toner particles;
(5) a step of filtering and washing the toner particles from the toner particle dispersion;
The static charge according to any one of claims 1 to 7, comprising: (6) a step of drying the washed toner particles; and (7) a step of adding and treating an external additive to the toner particles obtained by drying. The present invention relates to a method for producing a toner for developing an electrostatic latent image.

The toner of the present invention is excellent in resistance to stress, particularly mechanical stress in a development restricting portion in one-component development, and the durability is remarkably improved.
Even when the toner of the present invention is used as a full-color toner, the surface property of the toner is uniform for each color, so that the charging property is improved.
The toner of the present invention is oilless and can be fixed at a low temperature, and is excellent in blocking resistance (storage stability).

<Structure of toner particles>
The toner for developing an electrostatic latent image of the present invention is obtained by adhering / fusing shell resin particles B to the surface of core particles obtained by aggregating / fusing at least core resin particles A in an aqueous medium. The toner contains core-shell structure type toner particles. In the present invention, the resin component b1 that is softer than the core resin particle A and the hard resin component b2 are used as essential components as the resin particles B for the shell constituting the shell layer on the surface of the core particles. As a result, the soft resin component b1 acts as a fusion promoting component, so that the hard resin component b2 can be firmly adhered to the core particle surface, and the shell layer can be uniformly formed. The entire shell layer can be made a uniform shell layer with high mechanical strength. As a result, a toner structure having high durability against mechanical stress at the development restricting portion can be obtained.

In the present invention, the resin particle B for shell may have a particle structure including the resin components b1 and b2 as separate particles, or a composite particle structure having a resin layer of each of the resin components b1 and b2 in individual particles. There may be. Depending on the configuration of such particles B, the toner particles may have a structure as shown in FIGS. FIG. 1 is a schematic configuration diagram of toner particles. For example, the toner particle shown in FIG. 1 (I) is a composite resin particle B for a shell having a resin layer for each of the resin components b1 and b2, and the resin component b2 particle (2) is coated with the resin component b1 (3). The shell resin particles B (4) thus formed are adhered / fused to the core particles (1). Further, for example, in the toner particles shown in FIG. 1 (II), resin component b1 particles (5) and resin component b2 particles (6) are randomly attached / fused to the core particles (1). Further, for example, the toner particles shown in FIG. 1 (III) are obtained by adhering / fusion of the resin component b2 particles (6) after the resin component b1 particles (5) are adhered to the core particles (1). Yes. 1 (I) to (III), the core particles (1) are formed by agglomerating / fusion of at least the core resin particles A.
Among these toner particle structures, from the viewpoint of the uniformity of the shell layer, which is important for ensuring stress resistance, it is preferable to have the structures (I) and (II), particularly the structure (I). .

In the present specification, “aggregation” is used in a concept intended to simply attach at least a plurality of resin particles. By “aggregation”, so-called hetero-aggregated particles (group) are formed in which the constituent particles are in contact with each other, but no bonding due to melting of resin particles or the like is formed. A group of particles formed by such “aggregation” is referred to as “aggregated particles”.
"Fusion" is used in a concept that is intended to form a bond as a unit of use and handling by forming a bond due to melting of resin particles etc. in at least a part of the interface of the individual constituent particles in the aggregated particles And The particle group that has undergone such “fusion” is referred to as “fused particles”.
“Aggregation / fusion” refers to an action in which aggregation and fusion occur simultaneously or in stages, or an action in which aggregation and fusion occur simultaneously or in stages.
“Adhesion / fusion” refers to an action in which adhesion and fusion occur simultaneously or stepwise, or an action that causes adhesion and fusion to occur simultaneously or stepwise.

<Core particles>
The weight average molecular weight (MwA) of the resin particles A constituting the core particles is usually 15,000 to 200,000, preferably 15,000 to 170,000, more preferably 20,000 to 150,000. The
The resin particle A may be composed of a plurality of resin particles having different molecular weights (for example, high molecular weight resin particles, intermediate molecular weight resin particles, and low molecular weight resin particles), or a resin having different molecular weights is multilayered by a multistage polymerization method. You may be comprised from the resin particle (composite resin particle) made (composite). That is, the core particle aggregates / fuses a plurality of resin particles having different molecular weights with colorant particles if desired, and also aggregates / fuses the composite resin particles with colorant particles as desired. Can be obtained. As described above, when the core particle includes a plurality of resins having different molecular weights, the weight average molecular weight of the entire core particle may be within the above range.

The weight average molecular weight (Mw) of the high molecular weight resin particles (high molecular weight component of the composite resin particles) constituting the resin particles A is usually 160,000 to 500,000. By using resin particles A composed of such high molecular weight resin particles (high molecular weight component), sufficient internal cohesive force (offset resistance at high temperature) can be imparted to the obtained toner.
The weight average molecular weight (Mw) of the low molecular weight resin particles (low molecular weight component of the composite resin particles) constituting the resin particles A is usually 15,000 to 20,000. By using the resin particles A composed of such low molecular weight resin particles (low molecular weight component), excellent fixability (adhesive force to the image forming support) can be imparted to the obtained toner.
The weight average molecular weight (Mw) of the intermediate molecular weight resin particles (intermediate molecular weight component of the composite resin particles) constituting the resin particle A is usually set to 20,001 to 159,999.

  The glass transition temperature of the resin particles A is preferably in the range of 0 to 80 ° C, more preferably in the range of 30 to 70 ° C. If it is higher than this range, the fixing temperature becomes too high or the OHP translucency deteriorates. On the other hand, if it is lower than this range, toner blocking properties and storage stability deteriorate.

  The resin particles A are not particularly limited as long as they are resin particles that can be stably dispersed in an aqueous system, and known resin composition systems and production methods can be applied. In particular, from the viewpoints of toner fixing properties and storage stability, styrene acrylic copolymer resins, polyester resins, and the like are preferably used. For example, as a production method for obtaining a styrene acrylic resin, an emulsion polymerization method or a suspension polymerization method is suitable. When obtaining polyester resin particles, a previously obtained polymer is dissolved in a solvent and suspended in an aqueous system. It can be easily obtained by such a method. In particular, when the low molecular component, the high molecular component, and the middle molecular component are combined and used as described above, resin particles obtained by multistage polymerization by an emulsion polymerization method are preferable from the viewpoint of manufacturability. These resin particles A preferably have a weight average particle diameter in the range of 50 to 500 nm. The particle size of these resin particles, resin particles B described later, waxes described later, and colorant dispersions should be measured using a dynamic light scattering particle size distribution analyzer: Microtrac UPA150 (manufactured by Honeywell). Can do.

<Shell layer>
The weight average molecular weight (MwB) of the resin particles B constituting the shell layer is related to the weight average molecular weight (MwA) of the resin particles A by the relational expression (i);
MwA <MwB (i)
Is in a range where Moreover, it is preferable that the weight average molecular weight (MwB) of the said resin particle B is 30,000-200,000. Stress resistance falls that MwB is below MwA.

In the present invention, the resin particle B is composed of a resin component b1 that is softer than the resin particle A and a hard resin component b2. Specifically, the resin component b1 is a resin having a molecular weight (Mwb1) smaller than the MwA of the resin particles A, and preferably has a glass transition temperature of 40 to 80 ° C., particularly 50 to 70 ° C. The resin component b2 is a resin having a molecular weight (Mwb2) larger than the MwA of the resin particle A, and preferably has a glass transition temperature of 40 to 80 ° C, particularly 50 to 70 ° C. That is, the resin components b1 and b2 constituting the resin particle B are each represented by the relational expression (ii);
Mwb1 <MwA <Mwb2 (ii)
Each of these resins preferably has the above glass transition temperature. Mwb1 and Mwb2 are the weight average molecular weights of the resin components b1 and b2, respectively. It is only necessary that MwB of the entire resin particle B containing the resin component b1 and the resin component b2 satisfies the relational expression (i).

  As described above, the resin particle B may have a particle structure including the resin components b1 and b2 as separate particles, or each particle may have a resin layer of each of the resin components b1 and b2. May be. The particles having the latter structure are so-called composite resin particles obtained by multilayering (compositing) by, for example, a multistage polymerization method. Specifically, each particle satisfies the molecular weight ranges of the resin components b1 and b2. It has a resin layer. In this case, it is more preferable to have a configuration in which the resin component b2 particles are coated (encapsulated) with the resin component b1 from the viewpoint of improving the homogenization / film forming property of the shell layer.

  Even if the resin particle B has any of the above-described configurations, the resin particle B contains the low molecular weight resin component b1, so that the resin particle B can be fused to the surface of the core particle. The surface shape of the toner particles obtained can be smoothed. Moreover, the resin particle B exhibits high mechanical strength by containing the resin component b2. Further, by containing resin components b1 and b2 in combination, the hardness of the shell layer as a whole is increased, the disappearance of the interface in the shell layer and the smoothness of the toner surface are achieved, and the effect of significantly increasing the stress resistance of the toner Is demonstrated. If the resin component b2 is not contained or is contained, if Mwb2 is smaller than MwA, the stress resistance is lowered and a crushed toner piece is generated. Even if the resin component b1 is not contained or if Mwb1 is greater than MwA, the resin particle B cannot effectively adhere to the surface of the core particle, so that a uniform shell layer with a smooth surface and high mechanical strength is formed. As a result, the stress resistance decreases.

The weight average molecular weight (Mwb1) of the resin component b1 is in the range of 5,000 to 30,000, particularly 7,000 to 20,000, from the viewpoint of effectively exhibiting the fusing property and film forming property of the resin particles B. Preferably there is.
The weight average molecular weight (Mwb2) of the resin component b2 is preferably in the range of 4,000 to 300,000, particularly 30,000 to 200,000, from the viewpoint of effectively forming a tougher shell layer.

  The content ratio of the resin component b1 is preferably 5 to 65% by weight, more preferably 10 to 40% by weight, based on the total amount of the resin particles B. On the other hand, the content of the resin component b2 is preferably 35 to 95% by weight, more preferably 60 to 90% by weight, based on the total amount of the resin particles B. In addition to the resin components b1 and b2, it is also possible to use another functional material having an effect on the chargeability and fixability of the toner as the resin particles B.

  The resin particle B is not particularly limited as long as it is a resin particle that can be stably dispersed in an aqueous system, and a known resin composition system and production method can be applied. In particular, the resin component b1 that is necessary from the viewpoint of fusion and film-forming properties of the shell layer is preferably a relatively low molecular weight styrene acrylic copolymer resin or polyester resin. As the resin component b2 required from the viewpoint of the strength of the shell layer, a relatively high molecular weight styrene acrylic copolymer resin, polyester resin, or the like is preferably used. In particular, as a resin composition system excellent in mechanical strength for the resin component b2, a polymer obtained by stretching a polyester resin or a polyester prepolymer with urethane is preferably used, and has a cross-linked structure to further increase the strength. May be.

  For the resin components b1 and b2, an appropriate material system may be appropriately selected together with the resin particles A by a development system and a fixing system. Specific examples of the combination of resin particle A-resin component b1-resin component b2 include, for example, (1) StAc-StAc-StAc, (2) StAc-StAc-Pes, (3) StAc-Pes-StAc, (4) Examples include StAc-Pes-Pes, (5) Pes-StAc-StAc, (6) Pes-StAc-Pes, (7) Pes-Pes-StAc, and (8) Pes-Pes-Pes. “StAc” means a styrene acrylic resin, and “Pes” means a polyester resin.

  From the viewpoint of further improving the stress resistance, at least one of the resin component b1 or the resin component b2 is preferably a polyester resin. Examples of such combinations of resin particle A-resin component b1-resin component b2 include the combinations (2), (3), (4), (6), (7), and (8). Particularly preferred from the above viewpoint are combinations (4), (6) and (8) in which the resin component b2 is a polyester resin.

  It is preferable that either one of the resin component b1 or the resin component b2 is incompatible with the core resin constituting the core resin particle A. Examples of such a combination of resin particle A-resin component b1-resin component b2 include the combinations (2), (3), (6) and (7).

  From the viewpoint of ease of production and material cost, it is preferable that either the resin component b1 or the resin component b2 and the core resin particle A are made of a styrene / acrylic copolymer resin. Examples of such a combination of resin particle A-resin component b1-resin component b2 include the above combinations (2) and (3).

  Further, from the viewpoint of improving the fusion property and film-forming property in the shell layer, the core resin particles A and the resin component b1 are preferably the same material system. Examples of such a combination of resin particle A-resin component b1-resin component b2 include the combinations (1), (2), (7), and (8).

  As a means for obtaining the resin particle B, for example, when obtaining a styrene acrylic resin, an emulsion polymerization method or a suspension polymerization method is suitable. When obtaining a polyester resin particle, the polymer obtained in advance is dissolved in a solvent to obtain an aqueous solution. Can be easily obtained by a method such as suspension emulsification and dispersion and desolubilization. In particular, composite particles in which the b2 component is coated with the b1 component are suitable when the b1 component and the b2 component are used in a composite form as described above, and the high molecular weight is obtained by multistage polymerization of the emulsion polymerization method. Particles obtained by coating a styrene acrylic resin with a low molecular weight styrene acrylic resin, or those obtained by seed-polymerizing a styrene acrylic resin in an aqueous system with a high molecular weight polyester resin obtained in advance by emulsification and dispersion are suitably used. . The resin particles constituting these resin particles B preferably have a weight average particle size in the range of 50 to 500 nm.

<Ratio of resin particles A and B>
The blending weight ratio (core: shell) between the resin particles A constituting the core particles and the resin particles B constituting the shell layer is preferably 50:50 to 90:10. If the ratio of the resin particles B is too small, the effect of improving the mechanical strength of the toner by the shell layer cannot be obtained. On the other hand, if the ratio of the resin particles B is too large, the fixing temperature becomes too high.

<Measurement method of molecular weight>
Weight average molecular weight of resin particles A (individual weight average molecular weight and total weight average molecular weight (MwA) for a plurality of resin particles having different molecular weights) and weight average molecular weight of resin particles B (for a plurality of resin particles having different molecular weights) The individual weight average molecular weights (Mwb1) and (Mwb2) and the total weight average molecular weight (MwB)) are styrene-converted molecular weights measured using GPC (gel permeation chromatography).
As a method for measuring the molecular weight of a resin by GPC, 1 cc of THF is added to 0.5 to 5.0 mg (specifically, 1 mg) of a measurement sample, and the mixture is sufficiently dissolved by stirring with a magnetic stirrer at room temperature. Let
Next, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. As GPC measurement conditions, the column is stabilized at 40 ° C., THF is allowed to flow at a flow rate of 0.35 cc / min, and about 10 μl of a sample having a concentration of 1 mg / cc is injected for measurement. The column is preferably used in combination with a commercially available polystyrene gel column. For example, a combination of TSKgel Super HZ1000, HZ2000, HZ2500, HZ3000, HZ4000, HZM-N, HZM-M, HZM-H, TSKguardcolumn Super HZ-L, and HZ-H manufactured by Tosoh Corporation can be exemplified.
Moreover, as a detector, it is preferable to use a refractive index detector (IR detector) or a UV detector. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve measured using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for calibration curve measurement.

<Method for measuring glass transition temperature (Tg)>
Using a differential scanning calorimeter (DSC-200: manufactured by Seiko Electronics Co., Ltd.), 10 mg of a sample to be measured was accurately weighed, put in an aluminum pan, and heated as a reference using alumina in an aluminum pan. After the temperature was raised from room temperature to 200 ° C. at a rate of 30 ° C./min, this was cooled and measured between 20 ° C. and 150 ° C. at a rate of temperature rise of 10 ° C./min. The shoulder value of the main endothermic peak in the range of 90 ° C. was defined as Tg.

<Examples of materials and production examples constituting resin particles A and B>
Although the material and the manufacture example which comprise the resin particles A and B used by this invention are demonstrated concretely below, it is not limited to these at all.

-Material example and manufacture example of styrene acrylic resin particle For example, when obtaining a styrene acrylate-type copolymer by emulsion polymerization, superposition | polymerization is advanced by adding a radically polymerizable monomer sequentially. At this time, it is preferable to add a monomer having a polar group (a monomer having an acidic polar group or a monomer having a basic functional group). At this time, the monomers may be added separately, or a plurality of monomers may be mixed and added in advance. Further, it is possible to change the monomer composition during the monomer addition. The monomer may be added as it is, or may be added as an emulsion mixed and adjusted in advance with water, a surfactant or the like. As the surfactant, at least one selected from known cationic surfactants, anionic surfactants, and nonionic surfactants is used. Two or more of these surfactants may be used in combination. Among these, it is particularly preferable to mainly use an anionic surfactant.

Specific examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like.
Specific examples of anionic surfactants include sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate), sulfate ester salt (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, calcium oleate, etc.) can be exemplified as suitable ones. it can. Also, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and propylenoxide, sorbitan ester Nonionic surfactants such as can also be used. These surfactants are used as an emulsifier at the time of emulsion polymerization, but may be used for other steps or purposes.

  Examples of the radical polymerizable monomer used in the present invention include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, and pn-butyl. Styrenes such as styrene, p-tert-butylstyrene, p-nonylstyrene, p-phenylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, Acrylic acid esters such as 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, methacrylate 2-ethylhexyl methacrylate, etc. Le ethers, cyclohexene, acrylonitrile, methacrylonitrile, vinyl chloride, vinyl acetate and the like.

Examples of the monomer having an acidic polar group used in the present invention include monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and cinnamic acid, and monomers having a sulfonic acid group such as sulfonated styrene. Can be mentioned.
Monomers having basic polar groups include aminostyrene and quaternary salts thereof, nitrogen-containing heterocycle-containing monomers such as vinylpyridine and vinylpyrrolidone, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, etc. (Meth) acrylic acid ester having an amino group, and (meth) acrylic acid ester having an ammonium salt quaternized with these amino groups, acrylamide, N-propylacrylamide, N, N-dimethylacrylamide, N, N-dipropylacrylamide, N, N-dibutylacrylamide, acrylic acid amide, etc. can be mentioned.

  In the present invention, styrene, acrylic acid ester, and methacrylic acid ester are suitably used as the radical polymerizable monomer, and acrylic acid and methacrylic acid are suitably used as the monomer having an acidic polar group.

  As a crosslinking agent that further increases the mechanical strength of the toner, a radical polymerizable crosslinking agent may be added. Examples of such radically polymerizable crosslinking agents include divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, polyethylene glycol dimethacrylate, diallyl phthalate, butadiene, and isoprene. Examples include compounds having two or more unsaturated bonds. The addition ratio of the radical polymerizable crosslinking agent is preferably 0.1 to 10% by weight based on the monomer (monomer mixture) used together with the crosslinking agent.

  Water-soluble polymerization initiators used in the emulsion polymerization method include persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate, and a reducing agent such as acidic sodium sulfite with these persulfates as a component. Water-soluble polymerization initiators such as redox initiator, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide and cumene hydroperoxide, and these water-soluble polymerizable initiators as one component Redox initiator systems combined with reducing agents such as ferrous salts, benzoyl peroxide, 2,2′-azobis-isobutyronitrile and the like are used. These polymerization initiators may be added to the polymerization system before, simultaneously with the addition of the monomer, or after the addition, and these addition methods may be combined as necessary.

As the polymerization initiator used in the suspension polymerization method, an oil-soluble initiator is preferably used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis Azo compounds such as -4-methoxy-2,4-dimethylvaleronitrile; acetylcyclohexylsulfonyl peroxide, diisopropylperoxycarbonate, decanonyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, acetyl peroxide, t -Butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butylhydro Examples thereof include peroxide-based initiators such as peroxide, di-t-butyl peroxide and cumene hydroperoxide.
As for the usage-amount of a polymerization initiator, 0.1-10 weight part is preferable with respect to 100 weight part of monomers (monomer mixture) used for the superposition | polymerization by the said polymerization initiator.

  In the present invention, a known chain transfer agent can be used as necessary for adjusting the molecular weight of the polymer. Specific examples of such a chain transfer agent include n-octyl mercaptan, n- Dodecyl mercaptan, t-dodecyl mercaptan, 2-mercaptoethanol, diisopropylxanthogen, carbon tetrachloride, trichlorobromomethane, octanethiol, stearylthiol, n-octyl 3-mercaptopropionate, α-methylstyrene dimer, ethylene glycol bis (3 -Mercaptopropionate) and the like. The chain transfer agent may be used alone or in combination of two or more. The chain transfer agent is used in an amount of 0 to 5 parts by weight with respect to 100 parts by weight of the monomer (monomer mixture) used together with the chain transfer agent.

-Material example and manufacture example of polyester-type resin particle As a method of obtaining a polyester resin particle, the method of Unexamined-Japanese-Patent No. 11-7156 and the method of Unexamined-Japanese-Patent No. 13-209212 can be used, for example.
In the present invention, the polyester resin used as the binder resin is produced by subjecting a polyhydric alcohol component and a polyvalent carboxylic acid component as polymerization monomers to a polycondensation reaction in the presence of a catalyst as necessary. Specific examples of the polyhydric alcohol component of the polymerization monomer include polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2 -Bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,0)- Diols such as 2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, ethylene glycol, Diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, Pentyl glycol, hydrogenated bisphenol A, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, xylylene glycol, 1,4-cyclohexanedimethanol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol Bis- (β-hydroxyethyl) terephthalate, tris- (β-hydroxyethyl) isocyanurate, 2,2,4-trimethylolpentane-1,3-diol and the like are used. Furthermore, as a hydroxycarboxylic acid component, for example, p-oxybenzoic acid, vanillic acid, dimethylolpropionic acid, malic acid, tartaric acid, 5-hydroxyisophthalic acid and the like can be added.

  Specific examples of the polyvalent carboxylic acid component include malonic acid, succinic acid, glutaric acid, dimer acid, phthalic acid, isophthalic acid, terephthalic acid, isophthalic acid dimethyl ester, terephthalic acid dimethyl ester, terephthalic acid monomethyl ester , Tetrahydroterephthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, dimethyltetrahydrophthalic acid, endomethylenehexahydrophthalic acid, fumaric acid, naphthalenetetracarboxylic acid, diphenolic acid, trimellitic acid, pyromellitic acid, trimesic acid, Cyclopentanedicarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 2,2-bis- (4-carboxyphenyl) propane, trimellitic acid Anhydride and 4,4-dia Diimide carboxylic acid, tris- (β-carboxyethyl) isocyanurate obtained from nophenylmethane, isocyanurate ring-containing polyimide carboxylic acid, tolylene diisocyanate, xylylene diisocyanate or isophorone diisocyanate trimerization reaction product and trimellitic anhydride The isocyanate ring containing polyimide carboxylic acid etc. which are obtained from these are mentioned, These are used individually or in mixture of 2 or more types. In particular, when a trivalent or higher polyvalent carboxylic acid and a polyhydric alcohol are used, a crosslinked polyester resin is formed, and thus stability such as fixing strength and offset resistance can be improved. A desired polyester resin can be easily produced by polycondensation using these as raw materials by a conventionally known ordinary method.

<Examples of toner constituent materials>
Hereinafter, other toner constituent materials used in the present invention will be described in detail, but the present invention is not limited thereto, and conventionally known materials can be used.

Colorant Examples of the colorant constituting the toner of the present invention include various inorganic pigments, organic pigments, and dyes. A conventionally well-known thing can be used as an inorganic pigment. Any pigment can be used, but suitable inorganic pigments are exemplified below. Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite. These inorganic pigments can be used alone or in combination as required. The content of the inorganic pigment in the toner of the present invention is preferably 2 to 20 parts by weight, more preferably 3 to 15 parts by weight with respect to 100 parts by weight of the resin component (polymer).

A conventionally well-known thing can be used as an organic pigment. Although any pigment can be used, specific organic pigments are exemplified below.
Examples of pigments 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 81: 3, 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. Pigment red 184, C.I. I. Pigment red 185, C.I. I. Pigment red 222, C.I. I. Pigment red 238 and the like.

Examples of the orange or yellow pigment 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 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 138, C.I. I. And CI Pigment Yellow 180.
Examples of pigments 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 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

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.
These organic pigments and dyes can be used alone or in combination as desired.
The content ratio of the organic pigment and the dye in the toner of the present invention is preferably 2 to 20 parts by weight, more preferably 3 to 12 parts by weight with respect to 100 parts by weight of the resin component (polymer).

  These colorants are also preferably used in the form of a dispersion obtained by emulsifying in water in the presence of the known surfactant, and as a method for inclusion in the toner, they are collected together with the resin particles A in the aggregation step described later. A method can be exemplified. The colorant dispersion preferably has a dispersion particle diameter of 1 μm or less, more preferably in the range of 100 to 500 nm. If the average particle size exceeds 1 μm, the particle size distribution of the agglomerated particles deteriorates, which is a problem.

-Wax The toner particles constituting the toner of the present invention may contain a wax. As a method of incorporating the wax into the toner, a method of adding an emulsified dispersion of wax in a later-described aggregation step and agglomerating it together with the resin particles A, a resin emulsion obtained by seed-polymerizing a resin in a wax emulsion, or resin particles A or A method used as / and B, a method in which a wax is dissolved in a monomer and emulsified and dispersed in an aqueous system and miniemulsion polymerization is used as a resin particle A or / and B, or a resin obtained by the above miniemulsion polymerization Examples thereof include a method in which a resin obtained by further seed polymerization with a dispersion is used as the resin particles A and / or B. The shell layer may be formed using the resin particles B together with the resin particles B in the step of attaching the resin particles B to the core particles (shell forming step). From the viewpoint of further improving the low-temperature fixability, the wax is preferably encapsulated in at least one of the resin particles B, specifically, the resin component b1 or the resin component b2.
The method for producing the wax dispersion is, for example, emulsification as described in Reaction Engineering Research World Report-1 “Emulsification / Dispersion Technology and Particle Size Control of Polymer Fine Particles, Chapter 3” published in March 1995. -Any conventionally known method using a dispersing device or the like can be used.

  The wax dispersion (including a dispersion of wax-containing particles obtained by seed polymerization or miniemulsion polymerization) preferably has a dispersed particle size of 1 μm or less, and more preferably in the range of 100 to 500 nm.

  Examples of the wax include various known ones that can be dispersed in water. Specific examples of such waxes include olefinic waxes such as low molecular weight polyethylene, low molecular weight polypropylene, copolymerized polyethylene, grafted polyethylene, and grafted polypropylene, long chains such as behenyl behenate, montanate, and stearyl stearate. Higher grades such as ester waxes having aliphatic groups, plant waxes such as hydrogenated castor oil and carnauba wax, ketones having long chain alkyl groups such as distearyl ketone, silicone waxes having alkyl groups and phenyl groups, and stearic acid Fatty acids, higher fatty acid amides such as oleic acid amide, stearic acid amide, long chain fatty acid alcohols, long chain fatty acid polyhydric alcohols such as pentaerythritol, and their partial esters, paraffinic wax, Fischer-Tropschwak Like it is exemplified.

Suitable waxes constituting the toner of the present invention include those composed of a crystalline ester compound (hereinafter referred to as “specific ester compound”) represented by the following general formula (1).
Formula ^{(1): R 1 - (} OCO-R 2) n
(In the formula, R ¹ and R ² each independently represents an optionally substituted hydrocarbon group having 1 to 40 carbon atoms, and n is an integer of 1 to 4).

In General formula (1) which shows a specific ester compound, R < ¹ > and R < ² > show the hydrocarbon group which may have a substituent, respectively. The hydrocarbon group R ¹ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms. The hydrocarbon group R ² has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, more preferably 18 to 26 carbon atoms. In the general formula (1), n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4. The specific ester compound can be suitably synthesized by a dehydration condensation reaction between an alcohol and a carboxylic acid.

  Specific examples of the specific ester compound include compounds represented by the following formulas (1w) to (22w).

  Among these waxes, a wax having a melting point of 100 ° C. or lower is more preferable in order to improve fixability, and a more preferable wax has a melting point in the range of 40 to 100 ° C., particularly preferably in the range of 60 to 90 ° C. It is. When the melting point exceeds 100 ° C., the effect of reducing the fixing temperature is poor. In the presence of at least one emulsifier selected from the above-mentioned cationic surfactants, anionic surfactants, and nonionic surfactants, the wax particles used in the present invention or composite particles coated with a resin are used. It is obtained by emulsifying with. Two or more of these surfactants may be used in combination. Among these, it is particularly preferable to mainly use an anionic surfactant.

-Charge control agent As a charge control agent, well-known arbitrary things can be used individually or in combination. Considering color toner adaptability (the charge control agent itself is colorless or light and there is no color tone problem on the toner), quaternary ammonium salt compounds are positively charged, and salicylic acid or alkylsalicylic acid chromium is negatively charged. Metal salts with zinc, aluminum and the like, metal complexes, metal salts of benzylic acid, metal complexes, amide compounds, phenol compounds, naphthol compounds, phenol amide compounds and the like are preferable. For example, these charge control agents can be made into an emulsified dispersion using an emulsifier or the like, and can be contained in the toner in the same manner as the above-described colorant and wax. As the emulsifier (surfactant), for example, those described above are used. Of these, anionic and / or nonionic surfactants are preferred. When these are used, the charge control agent easily adheres, and the chargeability and charge stability of the resulting toner are improved.

<Toner production method>
The method for producing the toner of the present invention will be described below.
The production process of the present invention includes a step of forming a shell layer by adhering / fusing at least resin particles B to the surface of core particles obtained by agglomerating or agglomerating / fusing at least resin particles A in advance. It has the characteristics. Specifically, at least resin particles A are aggregated or aggregated / fused to form core particles, and at least resin particles B are adhered / fused to the surface of the obtained core particles to form a shell layer. Process.

As an example of the production method of the present invention,
(1) A step of producing a dispersion of core resin particles A,
(2) a step of producing a dispersion of resin particles B for shell,
(3) A step of aggregating or aggregating / fusing at least the core resin particles A in an aqueous medium to form core particles;
(4) a step of adhering / fusing at least the shell resin particles B to the surface of the core particles to form a shell layer to obtain core-shell structured toner particles;
(5) a step of filtering and washing the toner particles from the toner particle dispersion;
(6) A step of drying the washed toner particles, and (7) a step of adding and processing an external additive to the toner particles obtained by drying. Hereinafter, each step will be described.

(1) a polymerization step for producing resin particles A;
When preparing the resin particles A with a styrene acrylic resin, a conventionally known polymerization method (emulsion polymerization method, suspension polymerization method) can be basically employed. As an example of the polymerization method, a radical polymerization initiator is dissolved in an aqueous medium (an aqueous solution of a surfactant) and heated. When the temperature reaches a predetermined temperature (polymerization temperature), a radical polymerizable monomer (monomer mixture) is added. Add and heat the system with stirring, usually under a nitrogen atmosphere. Here, in the monomer mixture, it is preferable that at least one of a radical polymerizable monomer having an acidic group and a radical polymerizable monomer having a basic group is contained in a proportion of 0.1 to 20% by weight. The polymerization temperature and the polymerization time can be appropriately set within the range where the polymerization reaction occurs. The molecular weight of the resin particles A can be adjusted by the amount of the polymerization initiator, the reaction temperature, and further the addition of a chain transfer agent. When a chain transfer agent is used to adjust the molecular weight of the resin, it is preferable to add the chain transfer agent mixed with a radical polymerizable monomer. The particle diameter of the resin particles A thus obtained is preferably in the range of 50 to 500 nm in terms of weight average particle diameter.

  When resin particles (composite resin particles) obtained by multilayering (compositing) resins having different molecular weights as the resin particles A, that is, resin particles having a molecular weight distribution of two or more peaks are produced by a conventional method such as an emulsion polymerization method. It is preferable to adopt a method of preparing resin particles according to the above, adding a radically polymerizable monomer to the dispersion liquid of the resin particles and adding them to carry out polymerization to form a multilayer (composite).

When the resin particles A are prepared from a polyester resin, basically known methods for preparing polyester resin particles can be used.
In the present invention, the polyester resin is dissolved in a soluble organic solvent. The organic solvent used depends on the constituent components of the polyester, but usually, hydrocarbons such as toluene, xylene and hexane, halogenated hydrocarbons such as methylene chloride, chloroform and dichloroethane, ethanol, butanol and benzyl alcohol ether And alcohols such as tetrahydrofuran, ethers, esters such as methyl acetate, ethyl acetate, butyl acetate and isopropyl acetate, and ketones such as acetone, methyl ethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. The weight ratio of the resin to the organic solvent is in the range of 10/90 to 80/20 from the viewpoint of ease of formation of fine particles by suspension granulation and improvement in the yield of resin particles by subsequent aggregation, preferably 30 / It is the range of 70-70 / 30, Especially preferably, it is the range of 40 / 60-60 / 40.

The resin solution thus obtained is atomized and granulated in an aqueous medium. The fine particles are preferably granulated under high-speed shearing. In particular, in order to form fine particles, it is preferable to select a disperser equipped with a high-speed shearing mechanism, and among them, various types of homomixers, homogenizers, colloid mills, etc. More preferably, is used. At this time, the above-mentioned surfactant may be appropriately added for dispersion stabilization.
In the step of forming fine particles by granulation, the organic solvent is removed during or after granulation. This organic solvent may be removed by heating or under reduced pressure. In order to remove by heating, it is necessary to carry out at a temperature lower than the boiling point of the organic solvent to be removed and considering the Tg of the resin. In particular, when performed at a high temperature greatly exceeding the Tg of the resin, there is a problem that coalescence of the resin particles occurs. The removal of the organic solvent is usually preferably performed by stirring at a temperature around 40 ° C. for 3 to 24 hours. Moreover, when decompressing, it is desirable to carry out on the conditions of 20-150 mmHg.

The above styrene acrylic resin and polyester resin can be used in combination, or it is also possible to use a compound obtained by seed polymerizing styrene acrylic resin to polyester resin particles.
Furthermore, the present invention is not particularly limited to the materials and production methods exemplified above, and other resin material systems dispersed in an aqueous system can also be used.

(2) a polymerization step for producing resin particles B;
Similarly to the polymerization step for producing the resin particles A, a conventionally known polymerization method can also be adopted in this step. In the resin particle B, the resin component b1 having a lower molecular weight than the resin particle A and the resin component b2 having a higher molecular weight than the resin particle A can be separately prepared by the same means as the method for preparing the resin particle A. Alternatively, a composite particle structure in which the resin component b2 is coated with the resin component b1 may be used. As a means for this composite, when the resin components b1 and b2 are made of styrene acrylic resin, first, the resin component b2 is synthesized by emulsion polymerization to obtain a resin component b2 particle dispersion system, A multistage polymerization method in which the resin component b1 is synthesized by polymerization can be used. In the case where the resin component b2 is a polyester resin and the resin component b1 is a styrene acrylic resin, polyester resin particles are obtained in the same manner as when the resin particles A are prepared using a polyester resin, and then styrene acrylic resin is obtained. Composite particles can be obtained by seed polymerization with a resin. When the resin component b1 is a polyester resin and the resin component b2 is a styrene acrylic resin, the polyester resin that becomes the resin component b1 in the oil droplet of the styrene acrylic resin formulation that becomes the resin component b2 in the production method of the suspension polymerization method The styrene acrylic resin particle | grains coat | covered with the polyester-type resin can be obtained from the orientation in aqueous system by melt | dissolving and polymerizing.

(3) a step of obtaining core particles by aggregating or agglomerating / fusing at least resin particles A in an aqueous medium;
In this step, the toner constituting material particles including the resin particles A are aggregated by salting out, or aggregation and fusion are performed simultaneously or stepwise.
The salting-out is described in detail in, for example, literature and books on colloids, published by Polymer Publishing Co., Souichi Muroi, “Chemistry of Polymer Latex”, Chapter 6 and later. The electric double layer of dispersed particles in a solvent is compressed by an aggregating agent) to aggregate the particles.

  As the aggregating agent used in the present invention, the polarity of the polar functional group of the resin particles, the surfactant having the opposite polarity to the surfactant used in the dispersion of the resin particle dispersion or the colorant particles aggregated together with the resin particles, etc. In addition, a divalent or higher-valent inorganic metal salt can be preferably used. In general, the higher the valence, the greater the cohesive force. Therefore, the coagulant is selected in consideration of the particle aggregation speed and the stability of the production process in this step. Specific examples of the flocculant include, for example, metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, calcium polysulfide, etc. And inorganic metal salt polymers.

  In adding the flocculant, it is generally preferable to keep the temperature of the mixed dispersion liquid at 40 ° C. or less from the viewpoint of suppressing rapid aggregation in the system. When an electrolyte is added under conditions where the temperature exceeds 40 ° C., rapid aggregation occurs, which may make it difficult to control the particle size, and the bulk density of the obtained particles may be problematic. Further, usually, the particles are heated to cause coagulation and fusion to proceed simultaneously to produce fused particles. Stirring may be carried out in a reaction tank having a usual known stirring device such as a paddle blade, squid blade, three retreat blades, Max blend blade, double helical, etc., or a homogenizer, a homomixer, a Henschel mixer, etc. are used. You can also. The number of rotations of stirring is preferably set so that the system is in a turbulent state.

  In addition to the resin particles A, examples of the toner constituent material to be agglomerated as core particles in this step include a colorant, a wax, and a charge control agent. These toner constituent materials are not limited to be contained only in the core portion, and can be added and aggregated in the subsequent shelling step. In particular, it is preferable to add a colorant, wax or the like that is exposed on the surface of the toner particles and adversely affects the chargeability and image quality to the core portion.

  The particle size growth by the salting-out reaction is carried out until particles having a desired core particle size are obtained, but can be controlled relatively easily by adjusting the pH and temperature of the dispersion. The pH value varies depending on the zeta potential and isoelectric point of the reaction system, the type / amount of the flocculant used, the type / amount of emulsifier, and the target particle size of the toner. In the case of using a system flocculant, the pH at which the salting-out effect is effectively expressed is 2 to 6, and in the case of a magnesium system flocculant, the pH is 7 to 12.

  Similarly to pH, the reaction temperature cannot be uniquely defined, but it is preferable that the reaction temperature is in the range of 40 to 95 ° C. so that the particle size growth can be controlled. A temperature higher than this range is not preferable because the shape tends to be almost spherical due to the simultaneous progress of aggregation and fusion and lacks shape controllability. The reaction is maintained at a predetermined temperature for at least 10 minutes or more, and more preferably for 20 minutes or more to obtain toner particles having a desired particle diameter. If the reaction temperature is lower than the Tg of the resin, the particles only aggregate and the fusion does not proceed. If the reaction temperature is higher than the Tg, the aggregation and fusion of the particles proceed simultaneously. If the fusion does not proceed in this step, the fusion is carried out by raising the temperature at the end of this step or in the shelling step (4).

In this step, the temperature may be increased at a constant rate up to a predetermined temperature, or may be increased stepwise. You may adjust suitably the rotation speed of the stirring blade of a system.
The particle agglomeration speed and particle size control are performed by operating the reaction temperature and the number of revolutions of stirring while monitoring the agglomeration state of the particles in the system with a microscope or particle size measuring instrument until the desired particle size is reached. . When the desired particle size is reached, the process may proceed continuously to the shelling step of (4), or the cohesive force is reduced to stop the growth of the particle size of the system or slow the growth rate. An operation may be performed.

  As a means for reducing the cohesive force of the system, a means for increasing the stability of particles or a means for reducing the aggregating action of the aggregating agent can be used. For example, as a means to increase the stability of the particles, the pH of the system is adjusted to the stable side (for example, from the neutral to the alkaline side when agglomerating under acidic conditions, and from the neutral to the acidic side when aggregated under alkaline conditions. Or a method such as adding the above-mentioned surfactant is used. In addition, as a means for reducing the aggregating action of the aggregating agent, metal cations having different valences can be added, and the aggregating force can be remarkably reduced by an antagonistic action. It is possible to increase the temperature after reducing the cohesive force to promote fusion or control the shape to the spherical side.

  As other agglomeration / fusion methods, for example, JP 2001-255700 A (multi-stage aggregation process is described with an aluminum-based coagulant) and the above-mentioned JP-A 2002-116574 (multi-stage aggregation process is described with a salt mag flocculant). In addition, it is possible to use a method described in JP-A No. 11-7156 (description of a multistage aggregation process using a combination of polyester particles / nonionic activator).

(4) A process of forming at least resin particles B on the surface of the core particles to form a shell layer to obtain toner particles having a core-shell structure;
In this step, toner particles having a core-shell structure are obtained by forming a shell layer by adhering / fusing resin particles B (shell particles) to the surface of the core particles obtained in the above step. As the material to be adhered / fused to the surface of the core particle, not only the resin particle B but also the toner constituent material described above may be used. From the viewpoint of further improving the charging property and image quality of the toner, the resin particle Preferably only B is used. In this step, (i) a step of growing particles by attaching or adhering / fusing resin particles B to the surface of the core particles, and (ii) heat treatment after stopping the growth of the particles An aging process stage for performing the control.

In order to adhere / fuse the resin particles B to the surface of the core particles, it is preferable to carry out this step (shell formation step) in succession to the aggregation / fusion step for obtaining the core particles. That is, the dispersion of resin particles B was added to the dispersion of core particles obtained in the above step (3), and the desired particle size was reached in step (3) in order to grow the core particles. It is preferable to set the reaction temperature at the time or higher. A temperature range suitable for adhesion / fusion is (Tg _b1 +10) to (Tg _b1 + 50 ° C.), particularly preferably (Tg _b1 +15) to (Tg _b1 + 40 ° C.). Here, Tg _b1 is the glass transition temperature of the resin component b1 contained in the resin particle B.

  Further, as means for controlling the adhesion (that is, cohesiveness) of the shell particles to the core particles, the means mentioned in the above step (3) (adjustment of reaction temperature, system pH, stirring rotation speed, activator, etc.) are used. be able to. By the above means, it is desirable to set the conditions so that the shell particles adhere to the core while avoiding aggregation of the shell particles. In addition, when the shell particles do not adhere to the core particles by the above means, the coagulant used in the step (3) may be added as appropriate to increase the cohesive force and adhere.

  The appearance of the resin particles B adhering to the core particles and the appearance of fusion can be confirmed by observing the particle surface with an electron microscope by sampling during the reaction. After confirming that all shell particles floating in the system adhere to the core particles, the cohesive force of the system is completely lost, and the shape control is advanced until the desired circularity is achieved. The shape of the particles can be monitored at any time by the above-described shape measuring apparatus FPIA-2000.

When composite particles having a structure in which resin component b2 particles are coated with resin component b1 are used as resin particles B, toner particles having a structure as shown in FIG.
If the resin particles B are prepared by previously mixing the resin component b1 particles and the resin component b2 particles, toner particles having a structure as shown in FIG. (II) can be obtained.
Further, when the resin component b1 particle and the resin component b2 particle are used step by step as the resin particle B (specifically, when the resin particle component b1 particle is used first and then the resin component b2 particle is used), FIG. Toner particles having the structure shown are obtained.

  The shape of the toner particles having a core-shell structure obtained as described above (preferably the average circularity = 0.930 to 0.980) is the same as that of the core particles (preferably the average circularity = 0.850 to 0.001). 950) and the heating conditions in the aging stage of this adhesion / fusion process can be controlled.

(5) A step of filtering and washing the toner particles from a dispersion system (aqueous medium) of toner particles;
In this filtration / washing step, a filtration treatment for filtering the toner particles from the dispersion of toner particles obtained in the above step (4) and a surfactant from the filtered toner particles (cake-like aggregate) are performed. And a cleaning treatment for removing deposits such as aggregating agent.

  The filtration method is not particularly limited, and for example, a method 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 can be used.

  As a means for washing the filtered toner particles, a conventionally known washing method is used, for example, a method of reslurrying and stirring the filtered toner particles with pure water in a container equipped with a stirring device, A method such as applying pure water during vacuum filtration or centrifugal filtration is used. Further, at this time, in order to elute / remove the surfactant and metal salts remaining in the toner particles, an acidic or alkaline treatment may be performed in advance before washing with pure water.

(6) drying the washed toner particles;
Examples of the dryer used in this step include a spray dryer, a vacuum freeze dryer, a vacuum dryer, and the like. A stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary type dryer, and the like. It is preferable to use a dryer, a stirring dryer, or the like. The water content of the dried toner particles is preferably 5% by weight or less, more preferably 2% by weight or less.
In addition, when the toner particles that have been dried are aggregated due to weak interparticle attraction, the aggregate may be crushed. 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.

(7) A step of adding and treating an external additive to the particles obtained by drying;
In this step, single or plural kinds of external additives are added and mixed to the dried toner particles. Examples of apparatuses used for adding and mixing external additives include various known mixing apparatuses and surface reforming apparatuses such as a turbuler mixer, a Henschel mixer, a nauter mixer, a hybridizer, and a V-type mixer. be able to. When a plurality of types of external additives are added in this step, all the additives may be mixed at a time, or may be divided and mixed.
Furthermore, it is desirable to remove coarse particles from the obtained particles with a sieve having an opening of about 30 to 200 μm.

  External additives include various inorganic oxide fine particles such as silica, alumina, titania, strontium titanate and cerium oxide, hydrophobized fine particles as necessary, vinyl polymers, metal soaps such as zinc stearate and calcium stearate Etc. can be used. Particularly in the case of full-color toner, since the process becomes complicated, it is desirable to add functional particles that can further improve fluidity, chargeability, transferability, and cleaning properties. The addition amount of the external additive is preferably in the range of 0.05 to 5 parts by weight with respect to the toner particles.

<Toner physical properties>
Toner particle size The toner of the present invention preferably has a volume average particle size of 3 to 9 μm, more preferably 3 to 8 μm. In the toner production method, the particle size can be controlled by the concentration of the flocculant (salting out agent), the amount of organic solvent added, the fusing time, and the composition of the polymer.

The volume average particle diameter of the toner can be measured with a Coulter Counter TA-II or Coulter Multisizer II (manufactured by Beckman Coulter, Inc.). In the present invention, a Coulter Multisizer II is used, and an interface (Beckman Coulter, Inc.) that outputs a particle size distribution and a personal computer are connected. As the aperture in the Coulter Multisizer II, a 50 μm aperture was used, and the volume distribution of toner of 0.99 μm or more (for example, 2 to 40 μm) was measured to calculate the particle size distribution and average particle size.
Measurement conditions: (1) Aperture: 50 μm (2) Sample preparation method: Electrolyte [ISOTON-II-pc (manufactured by Beckman Coulter)] 50-100 ml, an appropriate amount of a surfactant (neutral detergent) was added and stirred, 10-20 mg of a measurement sample is added to this. This system is prepared by dispersing for 1 minute with an ultrasonic disperser.
Further, in the toner of the present invention, the ratio of toner particles having a size of 3 μm or less is preferably 20% by number or less, and the ratio of toner particles having a size of 2 μm or less is more preferably 10% by number or less.

Toner shape As the shape of the toner particles of the present invention, the average circularity (average circularity represented by the following formula) is preferably 0.930 to 0.990, more preferably 0.950 to 0. .980.
Circularity = (circle circumference obtained from equivalent circle diameter) / (perimeter of particle projection image)
When the circularity is higher than this range, the cleaning property in the process of the photosensitive member or transfer belt is remarkably deteriorated, which is not preferable. When the circularity is lower than this range, the toner has an irregular shape and the stress resistance at the development restricting portion is significantly deteriorated.

The distribution of circularity is preferably sharp, the standard deviation of circularity is preferably 0.10 or less, and the CV value calculated by the following formula is preferably less than 20%, more preferably 10 %.
CV value = (standard deviation of circularity / average circularity) × 100
By setting the standard deviation of the circularity to 0.10 or less, it is possible to obtain a toner having a uniform shape, and it is possible to reduce the difference in stress resistance and cleaning performance at the regulating portion between the toners. Further, by setting the CV value to less than 20%, it is possible to obtain a sharp shape distribution in the same manner, and the above effects can be exhibited more remarkably.

  The method for measuring the average circularity is not limited. For example, a photograph in which toner particles are magnified 500 times with an electron microscope is taken, and the circularity is measured for 500 or more toners using an image analyzer. The average circularity can be calculated by obtaining the arithmetic average value. Moreover, as a simple measuring method, it can measure with "FPIA-1000" (made by Toa Medical Electronics Co., Ltd.).

Toner thermal properties The toner of the present invention preferably has a softening point in the range of 70 to 150 ° C, more preferably 80 to 130 ° C, and still more preferably 85 to 120 ° C. When the softening point is lower than this range, storage stability and tackiness immediately after fixing during continuous paper feeding are remarkably deteriorated. A softening point higher than this range is not preferable because the fixing temperature becomes too high.

In the present specification, a method for measuring the softening point (Tm) of the resin / toner is shown below.
Using a flow tester (CFT-500: manufactured by Shimadzu Corporation), 1.0 g of a sample to be measured is weighed, a h1.0 mm × φ1.0 mm die is used, a heating rate is 3.0 ° C./min, and a preheating time is used. Measurement was performed under the conditions of 180 seconds, a load of 30 kg, and a measurement temperature range of 60 to 180 ° C., and the temperature at which the above sample flowed out 1/2 was defined as the softening point (Tm).

<Configuration of 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, 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 is used as a carrier. be able to.

<Process overview>
When the toner of the present invention is used as a one-component developer, an image forming apparatus suitable for mounting the developer will be briefly described with reference to FIG. Since the toner of the present invention is oilless and can be fixed at a low temperature, the apparatus shown in FIG. 2 includes an oilless fixing device as shown in FIG.

  FIG. 2 is a schematic configuration diagram of the image forming apparatus. This image forming apparatus uses four developing devices A1 to A4. The four developing devices A1 to A4 store toners of different colors of yellow, magenta, cyan, and black, and the four developing devices. A1 to A4 are held by a rotating holder 40, and the positions of the developing devices A1 to A4 are changed by the holder 40 so as to face the toner carrier 21 and the image carrier 10 in the developing devices A1 to A4. The toner carrier 21 and the image carrier 10 are respectively moved upward from below in a developing region where the toner carrier 21 and the image carrier 10 face each other.

  In forming a color image with this apparatus, for example, first, the toner carrier 21 in the first developing device A1 containing yellow toner is positioned so as to face the image carrier 10, and the image carrier is provided. 10, the surface of the image carrier 10 is uniformly charged by the charging device 41, and the image carrier 10 thus charged is exposed according to the image signal by the exposure device 42. An electrostatic latent image is formed on the surface of the image carrier 10.

  Next, the toner carrier 21 and the image carrier 10 are respectively moved downward in the development region where the image carrier 10 on which the electrostatic latent image is formed in this way and the toner carrier 21 in the first developing device A1 face each other. The yellow toner is supplied from the toner carrier 21 to the electrostatic latent image portion formed on the image carrier 10, and the yellow toner corresponding to the electrostatic latent image is supplied to the image carrier 10. Form an image.

  Then, the yellow toner image formed on the image carrier 10 in this way is transferred to an endless belt-like intermediate transfer member 43 that is stretched over the image carrier 10, while the image carrier after the transfer is transferred. The yellow toner remaining on the body 10 is removed from the image carrier 10 by the cleaning device 44. Similarly, magenta, cyan, and black toners are also transferred onto the intermediate transfer member 43 to form a full-color toner image.

  Then, a recording sheet 46 is guided from a paper cassette 45 provided in the lower part of the color image forming apparatus to a portion where the intermediate transfer member 43 and the transfer roller 48 face each other by a feed roller 47 and formed on the intermediate transfer member 43. The full-color toner image is transferred onto the recording sheet 46, and the full-color toner image thus transferred onto the recording sheet 46 is fixed on the recording sheet 46 by the oilless fixing device 49 and discharged, but not transferred. The toner remaining on the intermediate transfer member 43 is removed from the intermediate transfer member 43 by the cleaning device 50.

  FIG. 3 is a schematic configuration diagram of an oilless fixing device provided in the apparatus of FIG. This fixing device uses a heating roller 11 as a heating member and a pressure roller 12 as a pressure member. Specifically, the heating roller 11, the pressure roller 12 pressed against the heating roller to form a nip 24, the separation claw 13 for separating the fixed sheet from the heating roller, and the cleaning web for cleaning the surface of the heating roller 14, a web roller 15 around which the cleaning web is wound, and a winding roller 16 that winds up the cleaning web. The heating roller 11 usually has an elastic body layer 18 and a surface layer 19 on an aluminum cored bar 17 and a heater 20 inside the aluminum cored bar. The pressure roller 12 usually has an elastic layer 22 and a surface layer 23 on an aluminum cored bar 21. Fixing is performed by passing the recording sheet 25 carrying the toner image 26 from the right to the left in the drawing. The cleaning web 14, the web roller 15, and the winding roller 16 may be omitted as necessary.

  The image forming apparatus that can use the toner of the present invention is not limited to an apparatus that employs the one-component development method as described above, and is mixed with the carrier to form a two-component developer. You may use for the image forming apparatus provided with the apparatus. Further, the full color development method is not limited to the rotary method described above, and a tandem method or the like may be used. Furthermore, it can also be used for monochrome development.

Hereinafter, unless otherwise specified, “parts” means “parts by weight”.
(Resin dispersion used as resins A and B)
-Preparation of resin particle SMP1 In a 5000 ml separable flask equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device,
Dodecyl sulfate Na salt (SDS) 5 parts Deionized water 346.75 parts of a surfactant solution (aqueous medium) was charged, and the internal temperature was increased to 80 ° C. while stirring at a stirring speed of 300 rpm under a nitrogen stream. The temperature was raised. In this surfactant solution,
Polymerization initiator (potassium persulfate: KPS) 1.25 parts Ion exchange water Initiator solution in which 48.75 parts were dissolved was added, and the temperature was maintained at 80 ° C.
Styrene 76 parts n-butyl acrylate 22 parts methacrylic acid 2 parts n-octyl mercaptan 0.27 parts of monomer mixture was added dropwise over 1 hour, and this system was heated and stirred at 80 ° C for 2 hours. Latex (a dispersion of medium molecular weight resin particles) was prepared. This is referred to as “latex (SMP1)”. Table 1 shows the conditions for preparing this latex and the weight average molecular weight (Mw), glass transition point (Tg) and weight average particle diameter of the resin particles constituting the latex.

-Preparation of resin particles SMP2-3, SLP1-7, SHP1-4 Medium molecular weight latex SMP2-3, low molecular weight latex SLP1 by the same method as resin particle SMP1 except that the preparation conditions were changed as shown in Table 1 ˜7, high molecular weight latex SHP1-4 were prepared. Table 1 shows the weight average molecular weight (Mw), glass transition point (Tg), and weight average particle size of the resin particles constituting these latexes.

-Preparation of composite resin particles SMLP1 (1) Preparation of core particles (first stage polymerization): In a 5000 ml separable flask equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device,
Dodecyl sulfate Na salt (SDS) 4 parts Ion-exchanged water Surfactant solution (aqueous medium) dissolved in 2810 parts is charged, and the internal temperature is raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. I let you. In this surfactant solution,
Polymerization initiator (potassium persulfate: KPS) 10 parts Ion exchange water Initiator solution in which 390 parts were dissolved was added, and the temperature was maintained at 80 ° C.
Styrene 608 parts n-butyl acrylate 176 parts methacrylic acid 16 parts n-octyl mercaptan 2.16 parts of a monomer mixture was added dropwise over 1 hour, and this system was heated and stirred at 80 ° C for 2 hours. Polymerization (first stage polymerization) was performed to prepare a latex (a dispersion of resin particles made of a medium molecular weight resin). This is referred to as “latex (1M)” (solid content 20%).

(2) Formation of outer layer (second stage polymerization): 1875 parts of the latex (1M) obtained as described above was charged again into a 5 L separable flask,
Polymerization initiator (KPS) 7.0 parts Ion exchange water Initiator solution in which 1424.2 parts was dissolved was added,
Styrene 262.5 parts n-butyl acrylate 105.0 parts Methacrylic acid 7.5 parts N-octyl mercaptan 7.5 parts of a monomer mixture was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (second stage polymerization) was carried out by heating and stirring at 80 ° C. for 2 hours, followed by cooling to 30 ° C. and latex (a central portion made of a medium molecular weight resin and an outer layer made of a low molecular weight resin) A resin dispersion having This latex is referred to as “latex (SMLP1)” (solid content 20%). Table 1 shows the conditions for preparing this latex and the weight average molecular weight (Mw), glass transition point (Tg) and weight average particle diameter of the resin particles constituting the latex.

Preparation of composite resin particle SMLW1 (1) Formation of wax-containing layer (miniemulsion polymerization): In a flask equipped with a stirrer,
Styrene 262.5 parts n-butyl acrylate 105.0 parts methacrylic acid 7.5 parts n-octyl mercaptan 1.0 part of a compound represented by general formula (11w) (melting point 82 ° C.) 105 parts Was added and heated to 80 ° C. for dissolution to prepare a monomer solution.
on the other hand,
Anionic surfactant (polyoxyethylene lauryl sulfate Na)
1.2 parts Ion-exchanged water 41.6 parts of a surfactant solution was heated to 80 ° C., and this surfactant solution was added to a mechanical disperser “CLEARMIX” (M The above monomer solution was mixed and dispersed by Technic Co., Ltd. to prepare a dispersion (emulsion) containing emulsified particles (oil droplets) having a uniform dispersed particle size (110 nm).
Polymerization initiator (potassium persulfate: KPS) 12.8 parts Initiator solution in which 498.5 parts of ion-exchanged water are dissolved,
953.1 parts of ion exchange water was added and the system was heated to 80 ° C. Thereafter, the emulsion was added to this system and polymerized by heating and stirring at 80 ° C. for 3 hours to obtain a latex (dispersion of medium molecular weight resin particles containing wax). This is referred to as “latex (1M)”.

(2) Formation of outer layer (second stage polymerization): To the latex (1M) obtained as described above,
Polymerization initiator (KPS) 7.0 parts Ion-exchanged water An initiator solution in which 271.0 parts were dissolved was added, and under a temperature condition of 80 ° C,
Styrene 262.5 parts n-butyl acrylate 105.0 parts Methacrylic acid 7.5 parts N-octyl mercaptan 7.5 parts of a monomer mixture was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (second stage polymerization) was carried out by heating and stirring at 80 ° C. for 2 hours, followed by cooling to 30 ° C. and latex (from a center made of an intermediate molecular weight resin containing wax and a low molecular weight resin). A dispersion of composite resin particles having an outer layer was obtained, which was referred to as “latex (SMLW1)” (resin solid content 20%, WAX solid content 2.8%). Table 1 shows the weight average molecular weight (Mw), glass transition point (Tg), and weight average particle size of the resin particles constituting the resin particles.

・ Synthesis of polyester resin;
(Manufacture of polyester resin PES1)
Attach a reflux condenser, water separator, nitrogen gas inlet tube, thermometer, and stirrer to a 2 liter four-necked flask, and place it in a mantle heater. Polyoxypropylene (2,2) -2,2-bis The molar ratio of (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, fumaric acid and terephthalic acid is 9: 2: 5: 4. The mixture is charged with a polymerization initiator (dibutyltin oxide) and heated and stirred while introducing nitrogen into the flask. The number average molecular weight Mn is 4500, and the ratio of the weight average molecular weight Mw to the number average molecular weight Mn is Mw / A low molecular weight polyester resin (PES1) having a Mn of 3.0, a glass transition point of 59.5 ° C., and a softening point of 97.6 ° C. was obtained.

(Manufacture of polyester resin PES2)
Polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, terephthalic acid and trimellitic acid Except that the molar ratio is 7: 3: 7: 2, the number average molecular weight Mn is 5400, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 14.7, glass A high molecular weight polyester resin (PES2) having a transition point of 66 ° C. and a softening point of 119.9 ° C. was obtained.

-Preparation of resin particle PLP1 Polyester resin (PES1) 100 parts Ethyl acetate 150 parts A mixed solution in which the polyester resin was sufficiently dissolved was obtained using the above materials.
Dodecyl sulfate Na salt 2 parts Ion-exchanged water 400 parts This mixed solution is heated to 95 ° C and charged into a homomixer (Ace Homogenizer, manufactured by Nippon Seiki Co., Ltd.), and then a polyester resin solution is charged at 15,000 rpm. The mixture was stirred at a speed of 30 minutes for sufficient emulsification. The obtained emulsion was cooled, and ethyl acetate was distilled off under reduced pressure at 30 ° C. and 20 to 30 mmHg to obtain a polyester resin dispersion. This is referred to as “latex (PLP1)”. Table 1 shows the weight average molecular weight (Mw), glass transition point (Tg), and weight average particle size of the resin particles in this latex.

-Preparation of resin particle PHP1 A polyester resin dispersion was prepared in the same manner as the resin particle PLP1 except that PES2 was used as the resin. This is referred to as “latex (PHP1)”. Table 1 shows the weight average molecular weight (Mw), glass transition point (Tg), and weight average particle size of the resin particles in this latex.

  St; styrene, BA; n-butyl acrylate, MAA; methacrylic acid, HDDA; 1,6-hexanediol diacrylate.

-Preparation of latex A1-A6 As shown in Table 2 as a particle | grain A component, latex was mixed by specific solid content weight ratio, and latex A1-A6 was prepared.

Latex b11-b14 (b1 component) and b21-b25 (b2 component)
The latexes shown in Tables 3 and 4 were used as they were as the latexes b11 to b14 and b21 to b25.

-Preparation of latex BB1 After preparing latex b21 as component b2 by the above method,
Polymerization initiator (KPS) 1.90 parts An initiator solution in which 74.1 parts of ion-exchanged water was dissolved was added. A monomer mixture similar to that used in the preparation of latex b11 was dropped into this system over 1 hour under the temperature condition of 80 ° C. After completion of the dropping, polymerization (second stage polymerization) was carried out by heating and stirring at 80 ° C. for 2 hours. Then, it cooled to 30 degreeC, the dispersion liquid of the composite particle formed by b2 component particle | grains coat | covering with b1 component resin was obtained, and ion-exchange water was added and prepared so that resin solid content concentration might be 20%. This is referred to as “latex BB1”. Table 5 shows the weight average molecular weight (Mw), glass transition point (Tg), and weight average particle diameter of the resin particles constituting the latex. In addition, the usage-amount of a monomer liquid mixture (b1 component) is shown in Table 5 as solid content weight ratio of b2 component and b1 component.

Preparation of latexes BB2 to BB11 The latexes described as b2 component in Table 5 were first prepared, the same monomer mixture used in the preparation of the latex described as b1 component in Table 5, and b2 Latex BB2 to BB11 were obtained in the same manner as in the method for preparing latex BB1, except that the monomer mixture was used so that the solid weight ratio of the component and b1 component became the values shown in Table 5.

・ Latex B1-B3
As latexes B1 to B3, latexes (b2 component and b1 component) shown in Table 6 previously mixed at a specific solid content weight ratio were used.

Latex BBB1: Latex b22 and latex b11 are used to be added separately at a solid content weight ratio of 80:20, but are described as latex BBB1 for convenience.

(Colorant dispersion)
-Cyan colorant dispersion PC1
Pigment C.I. I. Pigment Blue 15: 3 50 parts by weight Dodecyl sulfate Na salt 10 parts by weight Ion exchange water 200 parts by weight The above materials were dispersed by a sand grinder mill to obtain a colorant dispersion having a volume average particle diameter (D50) of 170 nm.

-Magenta colorant dispersion PM1
In the production of the cyan colorant dispersion PC1, the pigment is C.I. I. A magenta colorant dispersion PM1 was prepared under the same conditions except that the pigment red 122 was changed to obtain a colorant dispersion having a volume average particle diameter (D50) of 180 nm.

・ Yellow colorant dispersion PY1
In the production of the cyan colorant dispersion PC1, the pigment is C.I. I. A yellow colorant dispersion PY1 was prepared under the same conditions except that the pigment yellow 74 was changed to obtain a colorant dispersion having a volume average particle diameter (D50) of 150 nm.

・ Black colorant dispersion PK1
In the production of the cyan colorant dispersion PC1, a black colorant dispersion PK1 was prepared under the same conditions except that the pigment was changed to carbon black (Mogal L; manufactured by Cabot), and the volume average particle diameter (D50) Gave a 180 nm colorant dispersion.

(Wax dispersion)
・ Wax dispersion W1
Ester wax represented by the above general formula (I) (melting point 82 ° C.) 50 parts by weight Dodecyl sulfate Na salt 3 parts by weight Ion-exchanged water 200 parts by weight The above components were 95 with a homogenizer (manufactured by LKA, Ultra Turrax T50). After sufficiently dispersing while heating to ° C., it was transferred to a pressure discharge type homogenizer and subjected to a dispersion treatment to obtain a wax fine particle dispersion having a volume average particle diameter (D50) of wax fine particles of 200 nm.

<Preparation of toner>
Example 1
80 parts of latex A1 (solid weight)
Ion-exchanged water 370 parts Colorant dispersion PC1 5 parts (solid weight)
12 parts of wax dispersion W1 (solid weight)
The above materials were charged and stirred in a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device. After adjusting the internal temperature to 30 ° C., 5N aqueous sodium hydroxide solution was added to this dispersion to adjust the pH to 11.0.
Magnesium chloride hexahydrate 32 parts Ion-exchanged water 32 parts Next, an aqueous solution composed of the above materials was added to the dispersion over 10 minutes at 30 ° C with stirring. After standing for 3 minutes, temperature increase was started, and the system was heated to 90 ° C. over 6 minutes (temperature increase rate = 10 ° C./min). In this state, the volume average particle diameter of the fused particles measured with “Coulter Multisizer-II (aperture diameter 50 μm)” is 6.0 μm, and is measured by a shape measuring device (FPIA) incorporated in-line. When the average circularity of the fused particles becomes 0.860,
Latex BB2 20 parts (solid weight)
When,
Magnesium chloride hexahydrate 12 parts Ion exchange water 12 parts of an aqueous solution was added and stirred for 30 minutes. Then
An aqueous solution consisting of 224 parts of sodium chloride and 896 parts of ion-exchanged water was added to stop the particle growth, and the fusion was continued by heating and stirring at a liquid temperature of 90 ° C. for 2 hours as an aging treatment. Then, it cooled to 30 degreeC on the conditions of 8 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced fused particles were filtered, washed repeatedly with ion exchange water, and then dried with hot air at 40 ° C. to obtain toner particles. 1000 parts of the toner particles thus obtained were put into a Henschel mixer (FM10B; manufactured by Mitsui Chemicals), and further hydrophobic silica (TG811F; manufactured by Cabot) 11 parts hydrophobic silica (NX90: manufactured by Nippon Aerosil Co., Ltd.) 7 parts 20 parts of strontium titanate particles (average particle size 300 nm) are added, mixed for 15 minutes under conditions of 3640 rpm, and the externally added toner particles are passed through a circular vibration sieve (75 μm mesh). The toner was obtained.

Examples 2 to 21 and Comparative Examples 1 to 12
A toner was obtained in the same manner as in Example 1 except that the particle A component, the particle B component, the colorant dispersion, and the wax dispersion described in Table 7 were used at the solid content weight described in Table 7. In addition, when latex BBB1 is used as the particle B component in Example 21, the order of addition of each material is that b1 component and magnesium chloride aqueous solution are added and stirred for 30 minutes, then b2 component is added and stirred for 20 minutes. Except for this, this is the same as the first embodiment.

In Comparative Example 9, the adhesion of shell particles to the core did not proceed, and the production was abandoned.
About the comparative example 8, the filtrate at the time of filtration was a little cloudy, and it was in the state which the shell particle did not adhere completely.

<Evaluation contents and evaluation method>
In the following, the evaluation carried out to confirm the effect of the toner of the present invention will be described, but it is not particularly limited to the process evaluated here.

<Stress resistance>
The color laser printer LP3000C (manufactured by Minolta Co., Ltd.) shown in FIG.
The evaluation was performed under an arbitrary environmental condition (HH / NN / LL), after performing a durability test on 2000 blank sheets using the LP3000C modified machine, taking out the evaluation toner, and using a reflection electron microscope, a magnification of 1000 times The field of view was changed 5 times, and the observation was performed 5 times, and the average number of crushed toners out of 500 toners was used. The evaluation criteria are shown below.
A: There is no crushing toner and there is no problem in practical use;
○: There are 1 to 2 crushing toners, but there is no practical problem;
Δ: There are 3 to 9 crushing toners, but there are no practical problems;
X: 10 or more crushing toners exist, and there is a problem in practical use.

<Low temperature fixability>
Evaluation was performed using the LP3000C modified machine.
The temperature of the fixing roller was set to 130 ° C., and a solid image with a total toner adhesion amount of 15 g / m ² was drawn. MT paper (basis weight 64 g / m ² ) was used as the paper. The image was folded in half from the middle and its peelability was judged visually.
○: No peeling occurred;
Δ: Some peeling occurred, but there was no practical problem;
X: There was a problem in practical use.

<Shelled state>
(Toner surface properties)
The toner particles before adding the external additive were observed with an electron microscope (SEM: manufactured by Hitachi). ○: The surface was smooth and rough, without protrusions and micropores;
Δ: The surface was slightly rough, and there were protrusions or micropores;
X: It was in the state where many roughness and micropores were seen on the surface.

(Shell particle adhesion efficiency)
The toner particle dispersion before washing was centrifuged and the turbid state of the supernatant was observed.
○: The supernatant liquid was transparent, and the shell particles were almost entirely attached as a shell layer;
Δ: The supernatant liquid was slightly turbid and the shell particles were not completely adhered;
X: The supernatant was cloudy and almost no shell particles were attached.

<Blocking resistance>
20 g of the toner was put in a glass bottle and allowed to stand at a high temperature of 50 ° C. for 24 hours, and then the toner was evaluated by visually confirming the toner.
○: No aggregation toner and no problem at all;
Δ: Light soft agglomeration exists, but it can be solved easily with a light force, and there is no practical problem;
X: A strong agglomerate was present, which could not be easily solved and had a problem in practical use.

<Chargeability>
The fog after printing 2000 sheets was evaluated.
○; No fog at all;
△: Slightly fogged, but no problem in practical use;
X: The fog was severe and there was a problem in practical use.

(I) to (III) are schematic sectional views of toner particles constituting the toner of the present invention. 1 is a schematic configuration diagram of an image forming apparatus suitable for a toner of the present invention. It is a schematic block diagram of the oil-less fixing device with which the apparatus of FIG. 2 is equipped.

Explanation of symbols

1; Core particle, 2; Resin component b2, 3; Resin component b1, 4; Resin particle B, 5; Resin component b1 particle, 6; Resin component b2 particle.

Claims (8)

An electrostatic latent image containing core-shell structured toner particles obtained by adhering / fusing shell resin particles B to the surface of core particles obtained by aggregating / fusing at least core resin particles A in an aqueous medium. A toner for development, wherein the blending weight ratio of the core resin particle A and the shell resin particle B (core: shell) is 50:50 to 90:10, and the shell resin particle B is the core resin particle A. A softer resin component b1 and a harder resin component b2 as essential components. An electrostatic latent image developing toner, wherein the following relationship is established when Mwb2.
MwA <MwB
Mwb1 <MwA <Mwb2   2. The electrostatic latent image developing toner according to claim 1, wherein the resin component b2 is a resin having a crosslinked structure.   3. The electrostatic latent image developing toner according to claim 1, wherein either one of the resin component b1 and the resin component b2 is incompatible with the core resin constituting the particles A.   The resin particle B for shell has a particle configuration including the resin components b1 and b2 as separate particles, or a particle configuration in which the resin component b2 particles are coated with the resin component b1. 4. The electrostatic latent image developing toner according to any one of 3 above.   Either one of the resin component b1 or the resin component b2 and the core resin particle A are made of at least a styrene / acrylic copolymer resin obtained by emulsion polymerization. Toner for electrostatic latent image development.   6. The electrostatic latent image developing toner according to claim 1, wherein either the resin component b1 or the resin component b2 is a polyester resin.   7. The electrostatic latent image developing toner according to claim 1, wherein either the resin component b1 or the resin component b2 includes a wax. (1) A step of producing a dispersion of core resin particles A,
(2) a step of producing a dispersion of resin particles B for shell,
(3) A step of aggregating or aggregating / fusing at least the core resin particles A in an aqueous medium to form core particles;
(4) A step of attaching / fusing at least the shell resin particles B to the surface of the core particles to form a shell layer to obtain core-shell structured toner particles;
(5) a step of filtering and washing the toner particles from the toner particle dispersion;
The static charge according to any one of claims 1 to 7, comprising: (6) a step of drying the washed toner particles; and (7) a step of adding and treating an external additive to the toner particles obtained by drying. A method for producing a toner for developing an electrostatic latent image.

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