JP6201448B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention relates to an electrostatic charge image developing toner used for electrophotographic image formation.

In recent years, in the field of electrophotographic image formation, development of image forming apparatuses and electrostatic charge image developing toner (hereinafter also simply referred to as “toner”) in response to market demands has been proceeding at a rapid pace. Yes.
For example, a toner having a sharp particle size distribution has been developed as a toner corresponding to high image quality. When a toner having a uniform particle size distribution in which the toner particles have a uniform particle size is used, the reproducibility of micro dots is remarkably improved due to the uniform development behavior of each individual toner particle. However, when the toner is manufactured by a conventional pulverization method, it is not easy to manufacture a toner having a sharp particle size distribution. On the other hand, an emulsion aggregation method has been proposed as a production method capable of arbitrarily controlling the shape and particle size distribution of toner particles. In this production method, the fine particle dispersion is mixed with the emulsified dispersion of fine resin particles and, if necessary, the wax dispersion, and while stirring, these fine particles are added by adding a flocculant or controlling pH. The toner particles are then agglomerated and the fine particles are fused by heating to obtain toner particles.
Further, from the viewpoint of energy saving, development of a low-temperature fixing toner capable of fixing with a small amount of heat energy is in progress. In order to lower the fixing temperature of the toner, it is necessary to use a resin having a low melting temperature or melt viscosity as the binder resin constituting the toner particles. However, a binder resin having a low melting temperature or melt viscosity has a low glass transition point and a low molecular weight, and thus causes new problems such as failure to secure the heat-resistant storage property of the obtained toner.

  To solve such problems, it has been proposed that the toner particles have a core-shell structure in order to obtain both low-temperature fixability and heat-resistant storage stability (see, for example, Patent Document 1). That is, by forming a shell layer made of a resin having a high softening point and excellent heat-resistant storage stability on the surface of the core particles excellent in low-temperature fixability, both low-temperature fixability and heat-resistant storage stability can be obtained. . In particular, the toner production method by the emulsion aggregation method has an advantage that such a higher-order structure can be easily controlled.

On the other hand, in recent years, in the production print area, in addition to the speedup of copiers and printers and the expansion of compatible paper types, it is possible to form an initial high-quality image without image defects over a long period of time. High durability has been demanded.
In order to obtain high reliability and high durability, it has been proposed to use a toner in which a resin containing a low molecular weight component, a high molecular weight component, or the like is introduced into a core particle or a shell layer (for example, Patent Document 2). 3). According to such a toner, the fusion property between the core and the shell and the film formability of the shell layer are improved by the low molecular weight component, and high crush resistance can be obtained by the high molecular weight component.

  However, in such toner, since both the core particle and the resin constituting the shell layer are styrene-acrylic resins, sufficient low-temperature fixability and heat-resistant storage properties are obtained to obtain high reliability and high durability. There is a problem that it is difficult to obtain.

  In order to solve such a problem, a toner using a polyester resin as a resin constituting the shell layer has been developed. (For example, refer to Patent Document 4). The polyester resin has an advantage that the softening point can be kept low while obtaining a high glass transition point as compared with the styrene-acrylic resin. By using the polyester resin for the shell layer, the low temperature fixability and heat resistant storage can be achieved. A toner having properties can be obtained.

  However, styrene-acrylic resin and polyester resin have poor affinity. When styrene-acrylic resin is used for the core particles and polyester resin is used for the shell layer, it is difficult to form a thin and uniform shell layer. Therefore, sufficient heat storage stability could not be obtained. In addition, since the adhesion between the core particles and the shell layer is low, it is difficult to produce toner particles with a smooth shell layer surface, and the shell layer is peeled off by stirring the toner in the developing machine during continuous printing. As a result, there has been a problem that white spots occur as image noise and the image quality deteriorates.

  In order to solve such a problem, a toner using an acrylic-modified polyester resin or a urethane-modified polyester resin as a resin constituting the shell layer has been proposed (see, for example, Patent Document 5).

  However, such a toner has a problem in that the gloss of the fixed image becomes excessively high by reducing the softening point of the resin in order to obtain low-temperature fixability.

JP 2005-221933 A JP 2000-292978 A Japanese Patent Laid-Open No. 2005-91436 JP 2005-338548 A JP2012-27179A

  The present invention has been made in consideration of the above circumstances, and its purpose is to obtain low-temperature fixability and heat-resistant storage stability, and to suppress the gloss of the formed image to be low, and to improve It is an object of the present invention to provide a toner for developing an electrostatic image having printing durability capable of forming an image having a high image quality over a long period of time.

The electrostatic image developing toner of the present invention comprises core particles made of a vinyl resin, and a shell layer made of an amorphous resin formed by bonding a vinyl polymer segment and a polyester polymer segment covering the core particle. Consisting of core-shell toner particles,
The amorphous resin has a glass transition point of 50 to 75 ° C.,
The content ratio of the vinyl polymerization segment in the amorphous resin is 1 to 25% by mass,
In the chromatogram showing the molecular weight distribution measured by gel permeation chromatography (GPC) of the amorphous resin, the ratio of the resin component having a molecular weight of 100,000 or more is 1 to 20 area%.

  In the electrostatic image developing toner of the present invention, the glass transition point of the vinyl resin constituting the core particle is preferably 20 to 40 ° C.

  According to the toner for developing an electrostatic charge image of the present invention, a specific amorphous resin formed by chemically bonding a core polymer particle and a vinyl polymer segment and a polyester polymer segment covering the core particle. Since it has a core-shell structure composed of a shell layer, low-temperature fixability and heat-resistant storage stability are obtained, the gloss of the formed image is suppressed to a low level, and an image with good image quality is formed over a long period of time. Printing durability that can be obtained.

  Hereinafter, the present invention will be specifically described.

The toner of the present invention is a non-crystalline resin (hereinafter also referred to as “vinyl-modified polyester resin”) in which a vinyl polymer segment and a polyester polymer segment are combined, each of which contains a vinyl resin core particle and a specific high molecular weight component. .)) Of toner particles having a core-shell structure comprising a shell layer.
Specifically, the glass transition point of the vinyl-modified polyester resin is 50 to 75 ° C., the content ratio of the vinyl polymerization segment in the vinyl-modified polyester resin is 1 to 25% by mass, and the gel permeation chromatography of the vinyl-modified polyester resin The ratio of the resin component having a molecular weight measured by (GPC) of 100,000 or more is 1 to 20% by area.

According to the toner as described above, it has a core-shell structure consisting of a core particle made of vinyl resin and a shell layer made of a specific vinyl-modified polyester resin covering the core particle, so that it has low temperature fixability and heat-resistant storage. In addition, the gloss of the formed image is suppressed to a low level, and further, the printing durability that can form an image with a good image quality over a long period of time is obtained.
The reason is considered as follows.
That is, basically, since it has a core-shell structure, both low-temperature fixing and heat-resistant storage stability can be achieved. The vinyl-modified polyester resin constituting the shell layer has a vinyl modification rate of 1 to 25% by mass, resulting in toner particles having a smooth surface. As a result, printing durability can be obtained. This is because the compatibility between the vinyl polymer segment and the vinyl resin constituting the core particle is adjusted to an appropriate one, so that a highly uniform shell layer can be formed, and the core can be formed during the production of toner particles. This is because an appropriate adhesion can be obtained between the core particle and the shell layer in order to reliably obtain a fusion property between the particle and the shell layer. When the adhesion between the core particle and the shell layer is excessively low, crushing occurs due to agitation in the developing device when an image is formed over a long period of time, and an image defect occurs.
Moreover, since the high molecular weight component of the vinyl-modified polyester resin constituting the shell layer is 1 to 20 area%, minute irregularities derived from the high molecular weight component can be formed on the surface of the fixed image, Low gloss is obtained.

In the present invention, “toner particles having a smooth surface” means a toner in which no dome-shaped protrusion is observed when the toner is observed using a scanning electron microscope “JSM-7401F” (manufactured by JEOL). Toner particles.
In the present invention, the toner having no dome-shaped protrusion is an arbitrary one of toner particles obtained by performing image processing from SEM image data photographed at a magnification of 10,000 with the above microscope. The number, diameter, and height of bumps in the area of 1 square micrometer are measured, and the same measurement is performed on any 10 toner particles, and the average value of the diameter and height per bump is calculated. The average value obtained is a toner having an average height of 50 nm or less and an average diameter of 100 nm or less. As for the number of bumps, those existing on the boundary line of the region are not counted.

  When the surface of the toner particles is not smooth, that is, when the shell layer is formed as a dome-shaped protrusion, sufficient heat-resistant storage stability cannot be obtained, and further, the external additive enters between the protrusions. Fluidity and charging stability due to the external additive cannot be obtained.

[Core particles]
The core particles constituting the toner particles according to the present invention contain a vinyl resin.

[Vinyl resin]
The vinyl resin constituting the core particle is formed using a monomer having a vinyl group (hereinafter referred to as “vinyl monomer”). Specifically, the vinyl resin is a styrene-acrylic resin. It can consist of a copolymer, a styrene polymer, an acrylic polymer, etc., and it is preferable that it consists of a styrene-acrylic copolymer.

The following can be used as the vinyl monomer. As a vinyl monomer, it can be used individually by 1 type or in combination of 2 or more types.
(1) Styrene monomer Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert -Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, and derivatives thereof.
(2) (meth) acrylic acid ester monomer (meth) methyl acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, T-butyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, (meth ) Diethylaminoethyl acrylate, dimethylaminoethyl (meth) acrylate, and derivatives thereof.
(3) Vinyl esters Vinyl propionate, vinyl acetate, vinyl benzoate and the like.
(4) Vinyl ethers Vinyl methyl ether, vinyl ethyl ether and the like.
(5) Vinyl ketones Vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone and the like.
(6) N-vinyl compounds N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like.
(7) Others Vinyl compounds such as vinyl naphthalene and vinyl pyridine, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

Moreover, as a vinyl monomer, it is preferable to use the monomer which has ionic dissociation groups, such as a carboxy group, a sulfonic acid group, and a phosphoric acid group, for example. Specific examples include the following.
Examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, and the like. Examples of the monomer having a sulfonic acid group include styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, and the like. Furthermore, examples of the monomer having a phosphate group include acid phosphooxyethyl methacrylate.

  Furthermore, polyfunctional vinyls can be used as the vinyl monomer, and the vinyl resin can have a crosslinked structure. Polyfunctional vinyls include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol Examples include diacrylate.

[Molecular weight of vinyl resin]
The vinyl resin preferably has a weight average molecular weight (Mw) calculated from a molecular weight distribution measured by gel permeation chromatography (GPC) of 20,000 to 60,000.
When the weight average molecular weight (Mw) of the vinyl resin is 20,000 or more, the gloss of the formed image can be suppressed from being excessively high, and sufficient heat-resistant storage stability can be reliably obtained. . Further, when the weight average molecular weight (Mw) of the vinyl resin is 60,000 or less, sufficient low-temperature fixability can be obtained.

Measurement of molecular weight distribution by GPC was performed as follows. That is, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0. The sample to be measured was poured at a rate of 2 ml / min, dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which the measurement sample (vinyl resin) was treated for 5 minutes using an ultrasonic disperser at room temperature, and then the pore size was 0.2 μm. A sample solution is obtained by processing with a membrane filter, and 10 μL of this sample solution is injected into the apparatus together with the carrier solvent described above, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample is simply determined. Using a calibration curve measured using dispersed polystyrene standard particles calculate. As a standard polystyrene sample for calibration curve measurement, molecular weights manufactured by Pressure Chemical Co., Ltd. are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1 .1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and at least about 10 standard polystyrene samples were measured, and a calibration curve It was created. A refractive index detector was used as the detector.

[Glass transition point of vinyl resin]
The glass transition point of the vinyl resin is preferably 20 to 40 ° C.
When the glass transition point of the vinyl resin is 20 ° C. or higher, sufficient heat-resistant storage stability can be reliably obtained. On the other hand, when the glass transition point of the vinyl resin is 40 ° C. or lower, sufficient low-temperature fixability can be reliably obtained.

The glass transition point (Tg) of the vinyl resin is a value measured using “Diamond DSC” (manufactured by Perkin Elmer).
As a measurement procedure, 3.0 mg of a measurement sample (vinyl resin) is sealed in an aluminum pan and set in a holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. to 100 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Perform analysis based on the data in Heat, draw a baseline extension before the rise of the first endothermic peak, and a tangent line indicating the maximum slope between the rise of the first peak and the peak apex, Let the intersection be the glass transition point.

[Shell layer]
The shell layer constituting the toner particles according to the present invention contains a vinyl-modified polyester resin formed by chemically bonding a vinyl polymer segment and a polyester polymer segment.
This shell layer preferably has a structure in which the core particles are completely covered. By having such a structure, heat-resistant storage property can be obtained reliably.
The vinyl-modified polyester resin that constitutes the shell layer has low compatibility with the vinyl resin that constitutes the core particles in the temperature range during storage of the toner.

[Vinyl modified polyester resin]
The vinyl-modified polyester resin is a resin formed by chemically bonding a vinyl polymer segment and a polyester polymer segment.

[Vinyl polymer segment]
The vinyl polymerization segment is formed of a vinyl monomer, and examples of the vinyl monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decyl Styrene monomers such as styrene, pn-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic Cyclohexyl acid, phenyl acrylate, methyl methacrylate, ethyl methacrylate, (Meth) acrylic acid such as butyl tacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate An ester monomer is mentioned, In addition to these, what was illustrated as a vinyl monomer for forming said vinyl resin can be used. Moreover, said vinyl monomer can be used individually by 1 type or in combination of 2 or more types.

  The vinyl polymer segment can be composed of a styrene polymer, an acrylic polymer, a styrene-acrylic copolymer, etc., and is preferably composed of a styrene-acrylic copolymer.

[Polyester polymerization segment]
The polyester polymerized segment is an amorphous one formed by a polyvalent carboxylic acid containing two or more carboxy groups in one molecule and a polyhydric alcohol containing two or more hydroxyl groups in one molecule. Specifically, it means one having no clear endothermic peak in differential scanning calorimetry (DSC).

Examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid Aliphatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc .; maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenyl succinic acid, n- Unsaturated aliphatic dicals such as dodecenyl succinic acid and n-octenyl succinic acid Phosphate; trimellitic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene-tricarboxylic acid, and the like trivalent or higher carboxylic acids, such as pyrene-tetracarboxylic acid.
A polyvalent carboxylic acid may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the polyhydric alcohol include, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1, 8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1, Aliphatic diols such as 18-octadecanediol and 1,20-eicosanediol; bisphenols such as bisphenol A and bisphenol F; and alkylene oxide adducts of bisphenols such as ethylene oxide adducts and propylene oxide adducts thereof; Glycerin, pentaeryth Tall, hexamethylol melamine, can be cited hexa ethyl melamine, tetramethylol benzoguanamine, etc. trihydric or higher polyols, such as tetra-ethyl benzoguanamine the.
A polyhydric alcohol may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the vinyl polymerization segment in the vinyl-modified polyester resin is 1 to 25% by mass, preferably 5 to 20% by mass.
Specifically, the content of the vinyl polymerization segment is determined based on the total mass of the resin material used for synthesizing the vinyl-modified polyester resin, that is, the polyvalent carboxylic acid and polyhydric alcohol serving as the polyester polymerization segment, and the vinyl polymerization segment. Is a ratio of the mass of the vinyl monomer to the total mass of the total of the vinyl monomer to be combined with the both reactive monomers for bonding them.
When the content of the vinyl polymerization segment is 25% by mass or less, the resin constituting the core particle and the resin constituting the shell layer are not excessively compatible during the production of the toner particles. A high shell layer can be formed and sufficient heat-resistant storage property can be obtained. On the other hand, when the content ratio of the vinyl polymer segment is 1% by mass or more, an appropriate affinity between the resin constituting the core particle and the resin constituting the shell layer can be obtained at the time of producing the toner particles. Adhesiveness with the shell layer can be sufficiently obtained, and as a result, high printing durability can be obtained.
The content ratio of the vinyl polymerization segment in the vinyl-modified polyester resin can be controlled by adjusting the amount of the monomer to be reacted when the vinyl-modified polyester resin is synthesized.

[Glass transition point of vinyl-modified polyester resin]
The glass transition point of the vinyl-modified polyester resin is 50 to 75 ° C.
When the glass transition point of the vinyl-modified polyester resin is 50 ° C. or higher, the obtained toner has a high thermal strength, and sufficient heat-resistant storage stability is obtained. On the other hand, when the glass transition point is 75 ° C. or lower, sufficient low-temperature fixability can be obtained.
The glass transition point of the vinyl-modified polyester resin can be controlled by adjusting the kind and amount of the monomer to be reacted when synthesizing the vinyl-modified polyester resin, and the molecular weight.

  The glass transition point of the vinyl-modified polyester resin is a value measured in the same manner as described above except that the vinyl-modified polyester resin is used as a measurement sample.

[Molecular weight of vinyl-modified polyester resin]
The weight average molecular weight (Mw) calculated from the molecular weight distribution measured by GPC of the vinyl-modified polyester resin is preferably 10,000 to 100,000.
When the weight average molecular weight (Mw) of the vinyl-modified polyester resin is 10,000 or more, it is possible to reliably suppress the gloss of the formed image from becoming excessively high while maintaining the low-temperature fixability. On the other hand, when the weight average molecular weight (Mw) is 100,000 or less, it is possible to reliably prevent the low-temperature fixability from being inhibited while maintaining the heat-resistant storage property.
The molecular weight distribution measurement by GPC of the vinyl-modified polyester resin is performed in the same manner as described above except that the vinyl-modified polyester resin is used as a measurement sample.

In addition, the vinyl-modified polyester resin has a resin component ratio (hereinafter also referred to as “high molecular weight component ratio”) having a molecular weight of 100,000 or more as measured by GPC of 1 to 20 area%, preferably 5 to 10 area%. It is supposed to be.
When the ratio of the high molecular weight component in the vinyl-modified polyester resin is 1 area% or more, minute unevenness derived from the high molecular weight component can be formed on the surface of the fixed image, and low glossiness can be obtained. When the high molecular weight component ratio is 20 area% or less, the low temperature fixability is inhibited.

The high molecular weight component ratio is as follows. In the chromatogram showing the molecular weight distribution measured by GPC as described above, the molecular weight is 100,000 when the area of the peak derived from the vinyl-modified polyester resin soluble in THF is 100% by area. The area ratio of the above resin components is said.
In the present invention, this high molecular weight component ratio is regarded as a weight ratio of a resin component having a molecular weight of 100,000 or more in the vinyl-modified polyester resin.

  In the toner particles according to the present invention, as the vinyl-modified polyester resin constituting the shell layer, only one kind having the molecular weight distribution of the above-described high molecular weight component ratio may be used, and the molecular weight distributions having different high molecular weight component ratios may be used. Two or more of them may be mixed and used so that the high molecular weight component ratio is in the above range as a whole.

  The high molecular weight component ratio of the vinyl-modified polyester resin is preferably controlled by adjusting the molecular weight of the polyester polymerization segment.

[Content of vinyl-modified polyester resin]
The content ratio of the vinyl-modified polyester resin to the total resin constituting the toner particles, that is, the binder resin is 5% by mass to 30% by mass, and preferably 7% by mass to 20% by mass.
When the content of the vinyl-modified polyester resin is 5% by mass or more, sufficient low-temperature fixability is obtained, and the affinity with the vinyl resin constituting the core particles is obtained, so that the shell layer is highly uniform. Can be formed. On the other hand, heat resistance storage property is not impaired by being 30 mass% or less.

[Method for producing vinyl-modified polyester resin]
The vinyl-modified polyester resin can be produced by bonding a polyester polymer segment and a vinyl polymer segment via both reactive monomers. Specifically, the polyvalent carboxylic acid / polyvalent for forming the polyester polymer segment at least at any time before, during and after the step of addition polymerization of the vinyl monomer for forming the vinyl polymer segment It can be produced by performing a condensation polymerization reaction in the presence of alcohol.
Specifically, an existing general scheme can be used. The following three methods are listed as typical methods.
(1) After performing an addition polymerization reaction of a vinyl monomer to form a vinyl polymerization segment, a polycondensation reaction of a polyvalent carboxylic acid and a polyhydric alcohol to form a polyester polymerization segment is performed. A method in which a tri- or higher valent vinyl monomer serving as a crosslinking agent is added to the reaction system to further advance the condensation polymerization reaction.
(2) After the polycondensation reaction of polyvalent carboxylic acid and polyhydric alcohol to form a polyester polymer segment, an addition polymerization reaction of a vinyl monomer to form a vinyl polymer segment is performed, and then necessary According to the method, a trivalent or higher valent vinyl monomer serving as a cross-linking agent is added to the reaction system, and the polycondensation reaction further proceeds under temperature conditions suitable for the polycondensation reaction.
(3) An addition polymerization reaction of a vinyl monomer for forming a vinyl polymerization segment and a polyvalent carboxylic acid and a polyhydric alcohol for forming a polyester polymerization segment under temperature conditions suitable for the addition polymerization reaction. After the polycondensation reaction is carried out in parallel and the addition polymerization reaction is completed, a trivalent or higher valent vinyl monomer as a cross-linking agent is added to the reaction system as necessary, under temperature conditions suitable for the polycondensation reaction. A method of further proceeding the condensation polymerization reaction.

  Both reactive monomers are added together with polyvalent carboxylic acid / polyhydric alcohol and / or vinyl monomer.

Both reactive monomers have at least one functional group selected from the group consisting of a hydroxyl group, a carboxy group, an epoxy group, a primary amino group and a secondary amino group in the molecule, preferably a hydroxyl group and / or a carboxy group. It is preferably a compound having a group, more preferably a carboxy group and an ethylenically unsaturated bond, that is, a vinyl carboxylic acid. Specific examples of the both reactive monomers include, for example, acrylic acid, methacrylic acid, fumaric acid, maleic acid and the like, and these hydroxyalkyl (C1-3) esters may be used. From this viewpoint, it is preferable to use acrylic acid, methacrylic acid and fumaric acid.
In addition, it is preferable to use a monovalent vinyl carboxylic acid as a bi-reactive monomer rather than a polyvalent vinyl carboxylic acid from the viewpoint of toner durability. This is probably because the reactivity between the monovalent vinyl-based carboxylic acid and the vinyl monomer is high, so that it can be easily hybridized. On the other hand, when a dicarboxylic acid such as fumaric acid is used as the bireactive monomer, the durability of the toner is slightly inferior. This is presumably because the reactivity between the dicarboxylic acid and the vinyl monomer is low and it is difficult to form a uniform hybrid, so that it takes a domain structure.

  The amount of the both reactive monomers used is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of vinyl monomers from the viewpoint of improving the low temperature fixability, high temperature offset resistance and durability of the toner. -8 parts by mass is more preferable, 0.3-8 parts by mass is preferable, and 0.5-5 parts by mass is more preferable with respect to 100 parts by mass of the total amount of the polyvalent carboxylic acid and the polyhydric alcohol.

  The addition polymerization reaction can be performed by a conventional method in the presence of a radical polymerization initiator, a crosslinking agent, or the like, in an organic solvent or in the absence of a solvent, but the temperature condition is preferably 110 to 200 ° C., and 140 to 180. ° C is more preferred. Examples of the radical polymerization initiator include dialkyl peroxide, dibutyl peroxide, butyl peroxy-2-ethylhexyl monocarboxylic acid and the like, and these can be used alone or in combination of two or more.

  The condensation polymerization reaction can be performed, for example, in an inert gas atmosphere at a temperature of 180 to 250 ° C., but is preferably performed in the presence of an esterification catalyst, a polymerization inhibitor, or the like. Examples of the esterification catalyst include tin (II) compounds having no Sn—C bond, such as dibutyltin oxide, titanium compounds, and tin octylate, and these may be used alone or in combination. it can.

[Ratio of core particle to shell layer in toner particles]
The mass ratio (core particle: shell layer) of the core particle and the shell layer in the toner particles according to the present invention is preferably in the range of 99: 1 to 80:20.
When the mass ratio of the shell layer in the toner particles is 1% by mass or more, sufficient heat-resistant storage stability can be reliably obtained. On the other hand, when the mass ratio of the shell layer in the toner particles is 20% by mass or less, sufficient low-temperature fixability is exhibited without being hindered.

  The molecular weight distribution and glass transition point of each resin can be measured using a vinyl resin extracted from toner particles and a vinyl-modified polyester resin as measurement samples, respectively.

[Extraction method of each resin]
As a method of extracting each resin from the toner particles, a method of separating using an appropriate solvent can be used.
Specifically, first, the toner is immersed in methyl ethyl ketone (MEK) and heated to near the boiling point. At this time, the vinyl-modified polyester resin is uniformly dissolved. Thereafter, the vinyl-modified polyester resin can be precipitated by cooling.
On the other hand, the solution in which the vinyl-modified polyester resin is deposited is centrifuged, and a vinyl resin is obtained from the separated supernatant.

  The toner particles may contain a resin other than the above-mentioned vinyl resin and vinyl-modified polyester resin as a binder resin.

[Configuration of toner particles]
The toner particles according to the present invention contain internal additives such as a colorant, a release agent, and a charge control agent in addition to the resin (binder resin) constituting the core particles and the shell layer. May be.
Each of the colorant, the release agent, and the charge control agent may be contained in the core particle, may be contained in the shell layer, or may be contained in both.

[Colorant]
As the colorant, generally known dyes and pigments can be used.
As a colorant for obtaining a black toner, various known materials such as carbon black such as furnace black and channel black, magnetic materials such as magnetite and ferrite, dyes, and inorganic pigments containing nonmagnetic iron oxide are arbitrarily selected. Can be used.
As the colorant for obtaining a color toner, known ones such as dyes and organic pigments can be arbitrarily used. Specifically, examples of the organic pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 166, 177, 178, 222, 238 269, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Blue 15; 3, 60, 76, and the like. Examples of the dye include C.I. I. Solvent Red 1, 49, 52, 58, 68, 11, 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, 69, 70, 93, 95 and the like.
The colorant for obtaining the toner of each color can be used singly or in combination of two or more for each color.
It is preferable that the content rate of a coloring agent is 1-10 mass parts with respect to 100 mass parts of binder resin, More preferably, it is 2-8 mass parts.

〔Release agent〕
The release agent is not particularly limited, and various known waxes can be used. For example, polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, and paraffins. Long-chain hydrocarbon waxes such as wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, penta Ester wacks such as erythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate , Ethylenediamine behenyl amide, an amide-based waxes such as trimellitic acid tristearyl amide.
The content ratio of the release agent is usually 1 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the binder resin. When the content ratio of the release agent is within the above range, sufficient fixing separation property can be obtained.

[Charge control agent]
Various known compounds can be used as the charge control agent.
The content ratio of the charge control agent is usually 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the binder resin.

[Average toner particle size]
The average particle diameter of the toner of the present invention is preferably 3 to 9 μm, and more preferably 3 to 8 μm, for example, on a volume basis median diameter. This particle size can be controlled, for example, by the concentration of the aggregating agent used, the fusing temperature, the fusing time, and the composition of the polymer when the emulsion polymerization agglomeration method described later is employed.
When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of the toner particles is measured and calculated using a measuring device in which “Multisizer 3” (manufactured by Beckman Coulter) is connected to a computer system equipped with data processing software “Software V3.51”. Is. Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Then, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion, and this toner dispersion is placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Pipet until the indicated concentration is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter is defined as the volume-based median diameter.

[Average circularity of toner particles]
The toner of the present invention preferably has an average circularity of 0.920 to 1.000, more preferably 0.930 to 0, from the viewpoint of improving the transfer efficiency of the individual toner particles constituting the toner. .960.

In the present invention, the average circularity of toner particles is measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the sample (toner particles) was blended with an aqueous solution containing a surfactant, and subjected to ultrasonic dispersion treatment for 1 minute to disperse. In the (high-magnification imaging) mode, photographing is performed at an appropriate density of 3,000 to 10,000 HPF detections, and the circularity of each toner particle is calculated according to the following formula (T). Calculated by adding the degree and dividing by the total number of toner particles.
Formula (T): Circularity = (perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)

[Toner Production Method]
The toner of the present invention can be produced by a kneading / pulverization method, a suspension polymerization method, an emulsion aggregation method, an emulsion polymerization aggregation method, and other various known methods, but the shell layer is uniformly formed on the surface of the core particles. It is preferable to use an emulsion aggregation method because it can be formed.
Specifically, the vinyl-modified material in which fine particles of vinyl resin dispersed in an aqueous medium are aggregated and fused to form aggregated particles that become core particles, and a shell layer is formed on the surface of the aggregated particles that become the core particles It is preferable to manufacture by an emulsion aggregation method in which toner particles are obtained by agglomerating and fusing fine particles of a polyester resin.

When the toner particles contain a colorant, a release agent, a charge control agent, etc., when these are contained in the core particles, the fine particles of the colorant are aggregated together when forming the agglomerated particles as the core particles. When these are contained in the shell layer, they may be added and aggregated at the same timing as the fine particles of the vinyl-modified polyester resin.
In addition, in the case of producing a toner using an emulsion polymerization aggregation method, when forming vinyl resin fine particles, a colorant, a release agent, and charge control are previously added to the monomer solution for forming the vinyl resin. These can be introduced into the toner particles by dissolving or dispersing the agent.

(External additive)
The above toner particles can constitute the toner of the present invention as they are, but in order to improve fluidity, chargeability, cleaning properties, etc., a fluidizing agent that is a so-called post-treatment agent is added to the toner particles. An external additive such as a cleaning aid may be added to constitute the toner of the present invention.

As the post-treatment agent, for example, inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium Inorganic titanic acid compound fine particles such as zinc acid are listed. These can be used individually by 1 type or in combination of 2 or more types.
These inorganic fine particles are preferably subjected to a gloss treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.

  The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner. In addition, various external additives may be used in combination.

  According to the toner of the present invention, since it has a core-shell structure comprising core particles made of vinyl resin and a shell layer made of a specific vinyl-modified polyester resin covering the core particles, low-temperature fixability and heat-resistant storage stability In addition, the gloss of the formed image is suppressed to a low level, and further, printing durability capable of forming an image with a good image quality over a long period of time is obtained.

(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.
As the carrier, for example, magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Among these, ferrite particles Is preferably used. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin-dispersed carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.
The carrier preferably has a volume average particle diameter of 15 to 100 μm, more preferably 25 to 80 μm.

[Image forming apparatus]
The toner of the present invention can be used in a general electrophotographic image forming method. As an image forming apparatus in which such an image forming method is performed, for example, a photosensitive member that is an electrostatic latent image carrier, A charging means for applying a uniform potential to the surface of the photoconductor by corona discharge having the same polarity as that of the toner, and an electrostatic latent image by performing image exposure on the surface of the uniformly charged photoconductor based on image data. An exposure means for forming an image; a developing means for conveying the toner to the surface of the photoreceptor to visualize the electrostatic latent image to form a toner image; and passing the toner image through an intermediate transfer member as necessary. For example, a transfer unit that transfers to a transfer material and a fixing unit that heat-fixes the toner image on the transfer material can be used.
The toner of the present invention can be suitably used at a relatively low temperature where the fixing temperature (the surface temperature of the fixing member) is 100 to 200 ° C.
In addition, the toner of the present invention is suitably used for a highly functional image forming method such as when outputting at high speed, when outputting to a thick paper as a transfer material, or when outputting a high quality image. Can do.

  As mentioned above, although embodiment of this invention was described concretely, embodiment of this invention is not limited to said example, A various change can be added.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Synthesis example 1 of vinyl-modified polyester resin]
To a 10 liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple,
-Bisphenol A propylene oxide 2-mole adduct (BPA-PO) 500 parts by mass-Terephthalic acid (TPA) 82 parts by mass-Fumaric acid (FA) 100 parts by mass-Trimellitic acid (TMA) 17 parts by mass-Esterification catalyst ( 2 parts by mass of tin octylate) was subjected to a polycondensation reaction at 230 ° C. for 8 hours, further reacted at 8 kPa for 1 hour, and cooled to 160 ° C.
-Acrylic acid (AA) 10 parts by mass-Styrene (St) 102 parts by mass-Butyl acrylate (BA) 21 parts by mass-Polymerization initiator (di-t-butyl peroxide) 10 parts by mass with a dropping funnel for 1 hour After dropping, the addition polymerization reaction was continued for 1 hour while keeping at 160 ° C., then the temperature was raised to 200 ° C. and held at 10 kPa for 1 hour, and then unreacted acrylic acid, styrene, By removing butyl acrylate, a vinyl-modified polyester resin [1] obtained by chemically bonding a vinyl polymer segment and a polyester polymer segment was obtained.
Table 1 shows the glass transition point and weight average molecular weight (Mw) of the vinyl-modified polyester resin [1], and the vinyl polymer segment content ratio in the vinyl-modified polyester resin [1].

[Synthesis Examples 2 to 8 of vinyl-modified polyester resin]
In the same manner as in Synthesis Example 1 of the vinyl-modified polyester resin, except that the monomer formulation shown in Table 1 below was followed, a vinyl-modified polyester resin formed by chemically bonding a vinyl polymer segment and a polyester polymer segment [ 2] to [8] were synthesized.
Table 1 shows the glass transition point and the weight average molecular weight (Mw) of these vinyl-modified polyester resins, and the vinyl polymer segment content ratio in the vinyl-modified polyester resin.

[Synthesis example 1 of styrene-acrylic resin]
In a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling tube, and a nitrogen introduction device, 2.0 parts by mass of an anionic surfactant “sodium lauryl sulfate” was dissolved in 2900 parts by mass of ion-exchanged water in advance. An anionic surfactant solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. After adding 9.0 parts by mass of a polymerization initiator “potassium persulfate (KPS)” to this surfactant solution and adjusting the internal temperature to 78 ° C.,
-Monomer solution (1)-
Styrene (St) 540 parts by mass n-butyl acrylate (BA) 270 parts by mass Methacrylic acid (MAA) 65 parts by mass n-octyl mercaptan (OM) 17 parts by mass of monomer solution (1) over 3 hours After completion of dropping, polymerization was carried out by heating and stirring at 78 ° C. for 1 hour, whereby a dispersion of fine particles of styrene-acrylic resin [1] was prepared.
Table 2 shows the glass transition point and the weight average molecular weight (Mw) of the styrene-acrylic resin [1].

[Synthesis example 2 of styrene-acrylic resin]
In Synthesis Example 1 of styrene-acrylic resin, a dispersion of fine particles of styrene-acrylic resin [2] was prepared in the same manner except that the formulation in Table 2 was followed.
Table 2 shows the glass transition point and the weight average molecular weight (Mw) of the styrene-acrylic resin [2].

[Synthesis Example 1 of Unmodified Polyester Resin]
An unmodified polyester resin [1] was synthesized in the same manner as in Synthesis Example 1 of the vinyl-modified polyester resin except that acrylic acid, styrene, butyl acrylate and a polymerization initiator were not added.
Table 3 shows the glass transition point and the weight average molecular weight (Mw) of the unmodified polyester resin [1].

[Synthesis Example 2 of Unmodified Polyester Resin]
An unmodified polyester resin [2] was synthesized in the same manner as in Synthesis Example 4 of vinyl-modified polyester resin except that acrylic acid, styrene, butyl acrylate and a polymerization initiator were not added.
Table 3 shows the glass transition point and the weight average molecular weight (Mw) of the unmodified polyester resin [2].

[Preparation Example 1 of Resin Fine Particle Dispersion for Shell]
The shell resin according to the prescription in Table 4 was used so that the total amount was 100 parts by mass, and this shell resin was pulverized with “Landel mill type: RM” (manufactured by Tokuju Kogakusha Co., Ltd.) and prepared in advance. Mix with 638 parts by mass of sodium lauryl sulfate solution with a concentration of 26% by mass and ultrasonically disperse for 30 minutes at 300 μA with V-LEVEL using an ultrasonic homogenizer “US-150T” (manufactured by Nippon Seiki Seisakusho) while stirring. Thus, shell resin fine particle dispersions [1] to [19] in which fine particles of the shell resin [1] to [19] were dispersed were prepared.
Table 4 shows the glass transition point (Tg) and the high molecular weight component ratio of the shell resins [1] to [19].

[Preparation example A1 of vinyl resin fine particle dispersion for core]
(1) Preparation of styrene-acrylic resin fine particle dispersion [A1] for core (1-1) First stage polymerization In a reaction vessel equipped with a stirrer, a temperature sensor, a temperature controller, a cooling pipe, and a nitrogen introducing device in advance An anionic surfactant solution prepared by dissolving 2.0 parts by mass of the anionic surfactant “sodium lauryl sulfate” in 2900 parts by mass of ion-exchanged water was added, and the internal temperature was adjusted while stirring at a stirring speed of 230 rpm in a nitrogen stream. The temperature was raised to 80 ° C. After adding 9.0 parts by mass of a polymerization initiator “potassium persulfate (KPS)” to this surfactant solution and adjusting the internal temperature to 78 ° C.,
-Monomer solution (1)-
A monomer solution (1) composed of 540 parts by mass of styrene, 270 parts by mass of n-butyl acrylate, 65 parts by mass of methacrylic acid, and 17 parts by mass of n-octyl mercaptan was added dropwise over 3 hours. A dispersion of resin fine particles [a1] was prepared by performing polymerization (first stage polymerization) by heating and stirring over time.

(1-2) Second-stage polymerization: formation of intermediate layer In a flask equipped with a stirrer,
-80 parts by mass of paraffin wax (melting point: 73 ° C) as a release agent was added to a solution consisting of 175 parts by mass of styrene, 85 parts by mass of n-butyl acrylate, 1 part by mass of n-octyl mercaptan, and heated to 85 ° C. And dissolved to prepare a monomer solution (2).
On the other hand, a surfactant solution in which 4 parts by mass of the anionic surfactant “sodium lauryl sulfate” was dissolved in 2063 parts by mass of ion-exchanged water was heated to 90 ° C., and the resin fine particles [a1 And 38 parts by mass in terms of solid content of the resin fine particles [a1], and then added to the monomer solution (2) using a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. Was mixed and dispersed for 4 hours to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 350 nm, and 4.5 parts by mass of a polymerization initiator “KPS” was dissolved in 85 parts by mass of ion-exchanged water. An initiator aqueous solution was added, and this system was heated and stirred at 90 ° C. for 2 hours to carry out polymerization (second stage polymerization), whereby a dispersion of resin fine particles [a11] was prepared.

(1-3) Third-stage polymerization: Formation of outer layer Initiator aqueous solution in which 7.7 parts by mass of polymerization initiator “KPS” is dissolved in 146 parts by mass of ion-exchanged water in the dispersion of the above resin fine particles [a11]. And at a temperature of 80 ° C.
-Monomer solution (3)-
-Monomer solution (3) consisting of 253 parts by mass of styrene, 147 parts by mass of n-butyl acrylate, and 5.5 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was carried out by heating and stirring for 3 hours. Then, it cooled to 28 degreeC and prepared the vinyl resin fine particle dispersion liquid [A1] for cores in which the microparticles | fine-particles by the styrene-acryl resin for cores were disperse | distributed in the anionic surfactant solution.
Table 5 shows the glass transition point of the core vinyl resin.

[Preparation Examples A2 to A3 of vinyl resin fine particle dispersion for core]
In the preparation example A1 of the vinyl resin fine particle dispersion for core, the monomer solution (3) used in the third-stage polymerization was the same as in Table 5, except that the vinyl resin fine particle dispersion [A2 ] To [A3] were prepared.
Table 5 shows the glass transition points of these vinyl resins for cores.

[Preparation Example of Colorant Fine Particle Dispersion Bk]
90 parts by weight of sodium dodecyl sulfate was dissolved in 1600 parts by weight of ion-exchanged water while stirring, and while stirring this solution, 420 parts by weight of carbon black “Mogal L” (manufactured by Cabot) was gradually added. A colorant fine particle dispersion [Bk] in which the colorant fine particles [Bk] are dispersed was prepared by carrying out a dispersion treatment using “CLEAMIX” (manufactured by M Technique Co., Ltd.). When the volume-based median diameter of the colorant fine particles [Bk] in the colorant fine particle dispersion [Bk] was measured using a Microtrac particle size distribution measuring device “UPA-150” (manufactured by Nikkiso Co., Ltd.), it was 117 nm.

[Example 1: Toner Production Example 1]
(Aggregation / fusion process)
Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 400 parts by mass of the core vinyl resin fine particle dispersion [A1] (in terms of solid content) and 2000 parts by mass of ion-exchanged water are added, and 5 mol / liter of water is added. An aqueous sodium oxide solution was added to adjust the pH to 10.
Next, 40 parts by mass of the colorant fine particle dispersion [Bk] (in terms of solid content) is added, and an aqueous solution in which 60 parts by mass of magnesium chloride is dissolved in 60 parts by mass of ion-exchanged water is stirred at 30 ° C. for 10 minutes. Added over time. Thereafter, the temperature was raised after being allowed to stand for 3 minutes, and the temperature of the system was raised to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Multisizer 3” (manufactured by Beckman Coulter), and when the volume-based median diameter reached 6.0 μm, the resin fine particle dispersion for shell [1] 40 parts by mass (in terms of solid content) is added over 30 minutes, and when the supernatant of the reaction solution becomes transparent, an aqueous solution in which 190 parts by mass of sodium chloride is dissolved in 760 parts by mass of ion-exchanged water is added to grow particles. Was stopped. Further, the temperature is raised and the mixture is heated and stirred in a state of 90 ° C. to advance the fusing of the particles, and the average circularity measurement apparatus “FPIA-2100” (manufactured by Sysmex) is used (HPF detection). When the average circularity measured was 4000, the mixture was cooled to 30 ° C. to obtain a dispersion of toner particles [1].
When the surface of the toner particles [1] was observed using a scanning electron microscope, it was smooth.
(Washing / drying process)
The dispersion of toner particles [1] is solid-liquid separated with a centrifuge to obtain a wet cake of toner particles, and this is used at 35 ° C. until the electric conductivity of the filtrate reaches 5 μS / cm using the centrifuge. After washing with ion-exchanged water, it was transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content became 0.5 mass%.
(External additive addition process)
To the dried toner particles [1], 1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 0.3% by mass of hydrophobic titania (number average primary particle size = 20 nm) are added, and a Henschel mixer is used. By mixing, toner [1] was obtained.

[Examples 2 to 13, Comparative Examples 1 to 8: Toner Production Examples 2 to 21]
In toner production example 1, toners [2] to [21] composed of toner particles [2] to [21] were produced in the same manner except that the formulation shown in Table 6 was followed.
The surface of the toner particles [2] to [21] was observed using a scanning electron microscope. The results are shown in Table 6.

[Developer Production Examples 1 to 21]
(1) Production of carrier 100 parts by mass of ferrite core and 5 parts by mass of copolymer resin particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) were put into a high-speed mixer equipped with stirring blades at 120 ° C. A carrier having a volume-based median diameter of 50 μm was obtained by stirring and mixing for 30 minutes to form a resin coat layer on the surface of the ferrite core by the action of mechanical impact force.
The volume-based median diameter of the carrier was measured with a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by Sympathic) equipped with a wet disperser.

(2) Mixing of toner and carrier To each of the toners [1] to [21], the above carrier is added so that the toner concentration becomes 6% by mass, and a micro-type V-type mixer The developer [1] to [21] was manufactured by mixing at a rotational speed of 45 rpm for 30 minutes.

  Using the above developers [1] to [21], the low-temperature fixability, heat-resistant storage property, image gloss and image stability (printing durability) were evaluated.

(1) Low-temperature fixability In the commercially available color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta), the fixing temperature is modified so that the fixing temperature of the upper fixing belt can be changed in the range of 120 to 200 ° C. The above-mentioned developer is used and a solid image with a toner adhesion amount of 11.3 g / m ² is output on the evaluation paper “NPi fine paper 128 g / m ² ” (manufactured by Nippon Paper Industries Co., Ltd.). The experiment was repeated until the set fixing temperature was increased from 120 ° C. in increments of 5 ° C. up to 200 ° C. The fixing speed was 350 mm / sec, and the temperature of the lower fixing roller was set 20 ° C. lower than the fixing temperature of the upper fixing belt.
Then, among the fixing experiments in which no cold offset occurs, the fixing temperature of the fixing experiment relating to the lowest fixing temperature was evaluated as the fixing lower limit temperature. The results are shown in Table 7. It can be said that the lower the fixing minimum temperature, the better the low-temperature fixing property.
In the present invention, a fixing lower limit temperature of less than 150 ° C. is determined to be acceptable.

(2) Heat-resistant storage stability Take 0.5 g of toner in a 10 mL glass bottle with an inner diameter of 21 mm, close the lid, and shake it 600 times at room temperature using a tap denser “KYT-2000” (manufactured by Seishin Enterprise Co., Ltd.). The sample was left in an environment of each experimental temperature and humidity of 35% RH for 2 hours. Next, the toner is placed on a 48-mesh (mesh 350 μm) sieve while being careful not to disintegrate the toner aggregates, set in a powder tester (manufactured by Hosokawa Micron), and fixed with a press bar and knob nut. After adjusting the vibration strength to a feed width of 1 mm and applying vibration for 10 seconds, the amount of residual toner remaining on the sieve was measured, and the toner aggregation rate, which is the ratio of the residual toner amount, was calculated by the following formula (1).
Formula (1): toner aggregation rate (mass%) = {remaining toner amount (g) /0.5 (g)} × 100
This agglomeration rate test was performed at various temperatures in which the experimental temperature was changed in increments of 2.5 ° C. in the range of 30 ° C. to 80 ° C.
Of the aggregation rate tests in which the toner aggregation rate is 50% or more, the lowest experimental temperature is called 50% aggregation temperature, and was evaluated as an index of heat-resistant storage stability. The results are shown in Table 7.
In the present invention, if the 50% aggregation temperature is 59 ° C. or higher, there is no practical problem and it is determined to be acceptable.

(3) Gloss of Image Using a commercially available color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta), loading the above developer, “POD128 g gloss coat (128 g / m ² )” (manufactured by Oji Paper Co., Ltd.) ) A solid image having a toner adhesion amount of 4 g / m ² was output. The fixing speed was 350 mm / sec, the fixing temperature of the upper fixing belt was 200 ° C., and the temperature of the lower fixing roller was 120 ° C. higher than the fixing temperature of the upper fixing belt.
The obtained solid image was measured for 75 ° gloss by “Micro Gloss 75 °” (manufactured by Gardner). The results are shown in Table 7.
In the present invention, if the 75 ° gloss is less than 61, it is acceptable.

(4) Image stability (printing durability)
Using a commercially available color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta), the developer was loaded, and 100 solid images were continuously output on “J paper” (manufactured by Konica Minolta). All 100 solid images are visually confirmed, and if the accumulated number of white spots on the image is 1 or less, it is judged as acceptable without any practical problem. The results are shown in Table 7.

Claims (2)

Core particles made of vinyl resin, and core-shell structure toner particles comprising a shell layer made of an amorphous resin formed by bonding vinyl polymer segments and polyester polymer segments, covering the core particles,
The amorphous resin has a glass transition point of 50 to 75 ° C.,
The content ratio of the vinyl polymerization segment in the amorphous resin is 1 to 25% by mass,
In the chromatogram showing the molecular weight distribution measured by gel permeation chromatography (GPC) of the amorphous resin, the ratio of the resin component having a molecular weight of 100,000 or more is 1 to 20% by area. Toner for charge image development. The toner for developing an electrostatic charge image according to claim 1, wherein the glass transition point of the vinyl resin constituting the core particle is 20 to 40 ° C.