JP7087500B2 - Toner for electrostatic latent image development and two-component developer for electrostatic latent image development - Google Patents

Description

The present invention relates to a toner for electrostatic latent image development and a two-component developer for electrostatic latent image development. More specifically, the present invention is excellent in charge rising property and stability of charge performance even in a low temperature and low humidity environment, and can form a high-quality image even when continuously printed in a low temperature and low humidity environment. , Toner for electrostatic latent image development and two-component developer for electrostatic latent image development.

In recent years, from the viewpoint of high speed and energy saving, toner for electrostatic latent image development (hereinafter, also simply referred to as toner) having excellent low-temperature fixability is required in order to fix a toner image with less energy than before. .. In order to lower the fixing temperature of the toner, it is necessary to lower the melting temperature and melting viscosity of the binder resin constituting the toner. In order to fix the toner at a low temperature, a toner containing a polyester resin as a main component of the binder resin has been proposed (see, for example, Patent Document 1). Since the polyester resin has a characteristic that the softening point is relatively low, it is advantageous in ensuring the low temperature fixability of the toner. Further, by reducing the particle size of the toner particles, it is possible to conceal the paper with a small amount of toner, and it is possible to reduce the energy required for fixing without lowering the image density.

By the way, in recent years, the demand for output of graphics and the like has increased, and the output of high image density printing has increased. Toners containing toner particles with a smaller diameter as described above have good reproducibility of fine latent images, and can achieve both energy saving and high image quality, and are therefore suitably used for high image density printing. Be done.
However, the toner particles having a smaller particle size have a problem that the fluidity is deteriorated. Especially in a low temperature and low humidity environment, the decrease in the fluidity of the developer becomes remarkable. As a result, there is a problem that the charge rising property of the toner is low, the toner is scattered, and the image quality is deteriorated when continuous printing is performed.

Further, it is known that titanium dioxide particles are added as an external additive for toner particles in order to improve the charge rising property. However, since the specific gravity of the titanium dioxide particles is large, the titanium dioxide particles are easily desorbed from the surface of the toner particles, and the desorbed titanium dioxide particles adhere to the surface of the carrier particles, which causes a problem that the charging performance of the carrier particles is deteriorated. be. Further, when this toner is used for continuous printing for a long time, there is a problem that the charged performance of the toner becomes unstable due to the desorbed titanium dioxide particles, and a high-quality image cannot be formed.

Japanese Unexamined Patent Publication No. 2016-57475

The present invention has been made in view of the above problems and situations, and the problem to be solved is that the charging rising property and the stability of the charging performance are excellent even in a low temperature and low humidity environment, and continuous printing is performed in a low temperature and low humidity environment. It is an object of the present invention to provide a toner for electrostatic latent image development and a two-component developer for electrostatic latent image development, which can form a high-quality image.

In order to solve the above-mentioned problems, the present inventor uses small-diameter spherical silica particles and a very small amount of titanium dioxide particles as an external additive for toner particles in the process of examining the cause of the above-mentioned problems at a low temperature. We provide toner for electrostatic latent image development that has excellent charge rise and stability of charging performance even in a low humidity environment and can form high-quality images even when continuous printing is performed in a low temperature and low humidity environment. We found out what to do and came up with the present invention.
That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. Toner for electrostatic latent image development that contains toner particles having an external additive on the surface of the toner matrix particles.
The median diameter based on the volume of the toner matrix particles is in the range of 3.0 to 5.0 μm.
As the external additive, at least the first spherical silica particles , the second spherical silica particles, and the titanium dioxide particles are contained.
The average primary particle diameter based on the number of the first spherical silica particles is in the range of 20 to 55 nm.
The average primary particle diameter based on the number of the second spherical silica particles is in the range of 70 to 160 nm.
The content of the first spherical silica particles with respect to the total amount of the toner matrix particles is in the range of 0.3 to 2.5% by mass.
The content of the second spherical silica particles with respect to the total amount of the toner matrix particles is in the range of 0.3 to 0.7% by mass.
A toner for electrostatic latent image development, wherein the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.01 to 0.50% by mass.

2. 2. The toner for electrostatic latent image development according to item 1, wherein the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.10 to 0.40% by mass.

3 . The toner for electrostatic latent image development according to the first or second item , which contains an amorphous polyester resin as the binder resin of the toner matrix particles.
4. The item according to any one of items 1 to 3, wherein the binder resin of the toner matrix particles contains an amorphous polyester resin, an amorphous vinyl resin, and a crystalline polyester resin. Toner for electrostatic latent image development.

5 . A two-component developer for electrostatic latent image development, which comprises the toner for electrostatic latent image development according to any one of items 1 to 4 and carrier particles.

6 . The carrier particles have a resin coating layer on the surface, and the carrier particles have a resin coating layer on the surface.
The two-component developer for electrostatic latent image development according to Item 5 , wherein the resin coating layer contains a copolymer formed by using an alicyclic (meth) acrylate monomer.

7 . Item 2. Two-component development for electrostatic latent image development according to Item 6 , wherein the copolymerization ratio (mass ratio) of the alicyclic (meth) acrylate monomer constituting the copolymer is 50% or more. Agent.

By the above means of the present invention, the present invention is excellent in charge rising property and stability of charging performance even in a low temperature and low humidity environment, and forms a high-quality image even when continuously printed in a low temperature and low humidity environment. It is possible to provide a toner for electrostatic latent image development and a two-component developer for electrostatic latent image development.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.

The toner particles according to the present invention contain titanium dioxide particles and small-diameter spherical silica particles as an external additive, so that the number of spherical silica particles adhering to the toner surface increases, so that the contact points with the carrier particles are increased. It is presumed that the number of particles will increase and that the particle charging will proceed quickly and the charging rising property will improve.
Further, since the toner particles according to the present invention have a very low content of titanium dioxide particles, the amount of titanium dioxide particles adhering to the surface of the carrier particles is also small, so that the toner of the present invention can maintain stable chargeability. It is inferred that.
Therefore, it is presumed that the toner of the present invention can form a high-quality image even when continuously printed in a low-temperature and low-humidity environment.

The electrostatic latent image developing toner of the present invention is an electrostatic latent image developing toner containing toner particles having an external additive on the surface of the toner matrix particles, and has a median diameter based on the volume of the toner matrix particles. It is in the range of 3.0 to 5.0 μm, and contains at least the first spherical silica particles , the second spherical silica particles, and the titanium dioxide particles as the external additive, and the first spherical silica. The average primary particle size based on the number of particles is in the range of 20 to 55 nm, and the average primary particle size based on the number of the second spherical silica particles is in the range of 70 to 160 nm. The content of the spherical silica particles with respect to the total amount of the toner matrix particles is in the range of 0.3 to 2.5% by mass, and the content of the second spherical silica particles with respect to the total amount of the toner matrix particles is 0.3. It is in the range of about 0.7% by mass, and the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.01 to 0.50% by mass. This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, from the viewpoint of more effectively obtaining the effect of the present invention, the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.10 to 0.40% by mass. Is preferable.

As an embodiment of the present invention, it is preferable to contain an amorphous polyester resin as the binder resin of the toner matrix particles from the viewpoint of improving the low temperature fixability of the toner.

The two-component developer for developing an electrostatic latent image of the present invention is characterized by containing the toner for developing an electrostatic latent image of the present invention and carrier particles.

In an embodiment of the two-component developer for electrostatic latent image development of the present invention, the carrier particles have a resin coating layer on the surface, and the resin coating layer uses an alicyclic (meth) acrylate monomer. It is preferable to contain the copolymer formed in the above process. Since the alicyclic (meth) acrylate monomer has low hygroscopicity, it is possible to suppress fluctuations in the amount of charge due to environmental differences. Further, from the viewpoint of effectively obtaining the effect of suppressing the fluctuation of the amount of charge, the copolymerization ratio (mass ratio) of the alicyclic (meth) acrylate monomer constituting the copolymer is 50% or more. preferable.

Hereinafter, the present invention, its constituent elements, and modes and embodiments for carrying out the present invention will be described. In addition, in this application, "-" is used in the sense that the numerical values described before and after it are included as the lower limit value and the upper limit value.

[Toner for developing static charge image]
The electrostatic latent image developing toner of the present invention is an electrostatic latent image developing toner containing toner particles having an external additive on the surface of the toner matrix particles, and is at least the first spherical silica as the external additive. It contains particles and titanium dioxide particles, and the average primary particle diameter based on the number of the first spherical silica particles is in the range of 20 to 55 nm, and the content of the titanium dioxide particles with respect to the total amount of the toner base particles is as follows. It is characterized in that it is in the range of 0.01 to 0.50 mass%.
The toner of the present invention is excellent in charge rising property and stability of charge performance even in a low temperature and low humidity environment, and can form a high-quality image even when continuous printing is performed in a low temperature and low humidity environment.
The toner particles according to the present invention contain titanium dioxide particles and small-diameter spherical silica particles as an external additive to improve the fluidity of the toner particles, so that the number of contact points with the carrier particles increases and the particles are charged. It is presumed that it will proceed quickly and the charge rising property will improve.
Further, since the toner particles according to the present invention have a very low content of titanium dioxide particles, the amount of titanium dioxide particles adhering to the surface of the carrier particles is also small, so that the toner of the present invention can maintain stable chargeability. It is inferred that.
Therefore, it is presumed that the toner of the present invention can form a high-quality image even when continuously printed in a low-temperature and low-humidity environment.

<Toner matrix particles>
The toner matrix particles according to the present invention preferably contain at least a binder resin.
In addition, the toner matrix particles according to the present invention may contain other constituent components such as a mold release agent (wax), a colorant, and a charge control agent, if necessary.

In the present invention, toner particles obtained by adding an external additive to toner matrix particles are referred to as toner particles, and an aggregate of toner particles is referred to as toner. Generally, the toner matrix particles can be used as they are as toner particles, but in the present invention, the toner matrix particles to which an external additive is added are used as the toner particles.

<Median diameter based on the volume of toner matrix particles>
The volume-based median diameter of the toner matrix particles according to the present invention is preferably in the range of 3.0 to 5.0 μm, and more preferably in the range of 3.5 to 4.5 μm.
In conventional toners, it is known to reduce the diameter of toner particles from the viewpoint of energy saving and high image quality. However, when the diameter of the toner particles is reduced, the fluidity is lowered, so that the contact probability between the carrier particles and the toner particles is lowered, and as a result, the toner particles are less likely to be charged and the charge rising property is lowered. The toner of the present invention is excellent in charge rising property even when the diameter of the toner particles is reduced so as to be within the above-mentioned predetermined range by increasing the contact points between the toner particles and the carrier. Therefore, the toner of the present invention has the effects of energy saving and high image quality by reducing the diameter of the toner particles so as to be within the above-mentioned predetermined range, and also when continuous printing is performed in a low temperature and low humidity environment. It is also possible to obtain the effect of being able to form a high-quality image.

The volume-based median diameter of the toner matrix particles is determined by the timing and amount of the amorphous polyester resin added in the aggregation / fusion step at the time of producing the toner matrix particles, which will be described later, the concentration of the flocculant and the amount of the solvent added. Alternatively, it can be controlled by the fusion time, further, the composition of the resin component, and the like.

(Measurement method of volume-based median diameter)
The volume-based median diameter of the toner matrix particles according to the present invention is measured using a measuring device in which a computer system for data processing (manufactured by Beckman Coulter) is connected to "Multisizer 3" (manufactured by Beckman Coulter).・ Calculated.
Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for the purpose of dispersing toner matrix particles, for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10-fold with pure water). After adding and acclimatizing, the mixture is dispersed with ultrasonic waves for 1 minute to prepare a dispersion of the toner matrix particles, and the dispersion of the toner matrix particles is used in the sample stand of "ISOTONII" (manufactured by Beckman Coulter). Inject into the contained beaker with a pipette until the indicated concentration of the measuring device reaches 5 to 10%. Here, by setting this concentration range, it is possible to obtain a reproducible measured value. Then, in the measuring device, the number of measured particles is 25,000, the aperture diameter is 100 μm, the frequency value is calculated by dividing the measurement range of 2 to 60 μm into 256, and the frequency value is calculated from the one with the largest volume integration fraction to 50. % Is the volume-based median diameter.

<Bundling resin>
The toner particles according to the present invention preferably contain an amorphous polyester resin as the binder resin from the viewpoint of improving the low temperature fixability of the toner. Further, it is preferable that the toner particles further contain an amorphous vinyl resin and a crystalline polyester resin as the binder resin.

(Amorphous polyester resin)
The amorphous polyester resin according to the present invention preferably contains the amorphous polyester resin in the range of 50 to 96% by mass, preferably 60 to 90% by mass, in the binder resin from the viewpoint of obtaining excellent fixability. It is more preferable to contain it in the range of%. The binder resin referred to here is the total amount of the toner resin.
The amorphous polyester resin according to the present invention is a polyester resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed. Further, since the monomer constituting the amorphous polyester resin is different from the monomer constituting the crystalline polyester resin, it can be distinguished from the crystalline polyester resin by, for example, analysis such as NMR.

The Tg of the amorphous polyester resin is preferably in the range of 35 to 80 ° C, and particularly preferably in the range of 45 to 65 ° C.

The glass transition temperature can be measured according to the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82. For the measurement, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer), or the like can be used.

The amorphous polyester resin is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). The specific amorphous polyester resin is not particularly limited, and conventionally known amorphous polyester resins in the present art can be used.

The specific method for producing the amorphous polyester resin is not particularly limited, and the polyvalent carboxylic acid and the polyhydric alcohol are polycondensed (esterified) by using a known esterification catalyst. Resin can be manufactured.
The catalyst that can be used in the production, the temperature of polycondensation (esterification), and the time of polycondensation (esterification) are not particularly limited, and are the same as those of the above crystalline polyester resin.

The weight average molecular weight (Mw) of the amorphous polyester resin is not particularly limited, but is preferably in the range of 5,000 to 100,000, and more preferably in the range of 5,000 to 50,000. When the weight average molecular weight (Mw) is 5000 or more, the heat-resistant storage property of the toner can be improved, and when it is 100,000 or less, the low-temperature fixability can be further improved. The weight average molecular weight (Mw) can be measured by the method described above.

Examples of the polyvalent carboxylic acid and the polyhydric alcohol used in the preparation of the amorphous polyester resin are not particularly limited, and examples thereof include the following.

《Polyvalent carboxylic acid》
Aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, and fats such as maleic anhydride, fumaric acid, succinic acid, alkenyl succinic acid anhydride, and adipic acid. Examples thereof include alicyclic carboxylic acids such as group carboxylic acids and cyclohexanedicarboxylic acids. One or more of these polyvalent carboxylic acids can be used. Among these polyvalent carboxylic acids, it is preferable to use an aromatic carboxylic acid, and a trivalent or higher carboxylic acid (tri) is used together with a dicarboxylic acid to form a crosslinked structure or a branched structure in order to secure better fixing property. It is preferable to use merit acid or its acid anhydride in combination.

Examples of trivalent or higher carboxylic acids include 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid. Etc., and examples thereof include these anhydrides and their lower alkyl esters. These may be used alone or in combination of two or more.

《Multivalent alcohol》
Alicyclic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin, cyclohexanediol, cyclohexanedimethanol, alicyclic diols such as hydrogenated bisphenol A, Examples thereof include aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. One or more of these polyhydric alcohols can be used. Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and among these, aromatic diols are more preferable. Further, in order to secure better fixing property, a trihydric or higher polyhydric alcohol (glycerin, trimethylolpropane, pentaerythritol) may be used in combination with the diol to form a crosslinked structure or a branched structure.

A monocarboxylic acid and / or a monoalcohol is further added to the polyester resin obtained by polycondensation of the polyvalent carboxylic acid and the polyhydric alcohol to esterify the hydroxy group and / or the carboxy group at the polymerization terminal. , The acid value of the polyester resin may be adjusted.
Examples of the monocarboxylic acid include acetic acid, acetic anhydride, benzoic acid, trichloracetic acid, trifluoroacetic acid, propionic anhydride and the like, and examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol and trifluoroethanol. , Trichloroethanol, hexafluoroisopropanol, phenol and the like.

(Amorphous vinyl resin)
The binder resin of the toner particles according to the present invention preferably contains an amorphous vinyl resin in the range of 0.1 to 20% by mass, and preferably in the range of 0.2 to 10% by mass. Is more preferable, and it is particularly preferable that the content is in the range of 0.3 to 5% by mass.
When the amorphous vinyl resin is contained in the range of 0.1 to 20% by mass, the surface of the toner matrix particles becomes moderately hard, so that the first spherical silica particles described later are embedded in the toner matrix particles. It is difficult, the charge rising property is improved during continuous printing, and the formed image quality is high. Further, when the amount of the amorphous vinyl resin is 20% by mass or less, good low temperature fixability can be obtained.
As the amorphous vinyl resin, the amorphous vinyl resin itself may be contained in the binder resin, or the amorphous vinyl resin component may be contained as a hybrid composite resin.

The vinyl resin according to the present invention is not particularly limited as long as it is a polymerized vinyl compound, and examples thereof include (meth) acrylic acid ester resin, styrene- (meth) acrylic acid ester resin, and ethylene-vinyl acetate resin. Can be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.
Among the above vinyl resins, styrene / (meth) acrylic acid ester resin is preferable in consideration of plasticity at the time of heat fixing. Therefore, in the following, a styrene / (meth) acrylic acid ester resin (hereinafter, also referred to as “styrene / (meth) acrylic resin”) as an amorphous resin will be described.

The styrene / (meth) acrylic resin is formed by addition polymerization of at least a styrene monomer and a (meth) acrylic acid ester monomer. The styrene monomer referred to here includes those having a known side chain or functional group in the styrene structure, in addition to the styrene represented by the structural formula of CH ₂ = CH _{—C 6H 5 .}
Further, the (meth) acrylic acid ester monomer referred to here is an acrylic acid ester derivative or a methacrylic acid ester derivative in addition to the acrylic acid ester or methacrylic acid ester represented by CH ₂ = CHCOOR (R is an alkyl group). It contains an ester having a known side chain or functional group in the structure of the above. In the present specification, "(meth) acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer".

An example of a styrene monomer and a (meth) acrylic acid ester monomer capable of forming a styrene / (meth) acrylic resin is shown below.
Specific examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, and 2,4-dimethylstyrene. , P-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene and the like. These styrene monomers can be used alone or in combination of two or more.

Specific examples of the (meth) acrylic acid ester monomer include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. , Stearyl acrylate, lauryl acrylate, phenyl acrylate and other acrylic acid ester monomers; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Examples thereof include methacrylic acid esters such as stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate and dimethylaminoethyl methacrylate. These (meth) acrylic acid ester monomers can be used alone or in combination of two or more.

The content of the structural unit derived from the styrene monomer in the styrene / (meth) acrylic resin is preferably in the range of 40 to 90% by mass with respect to the total amount of the resin. Further, the content of the structural unit derived from the (meth) acrylic acid ester monomer in the resin is preferably in the range of 10 to 60% by mass with respect to the total amount of the resin. Further, the styrene / (meth) acrylic resin may contain the following monomer compounds in addition to the above-mentioned styrene monomer and (meth) acrylic acid ester monomer.

Examples of such monomer compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, silicic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; 2-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl ( Examples thereof include compounds having a hydroxy group such as meth) acrylate. These monomer compounds can be used alone or in combination of two or more.

The content of the structural unit derived from the above-mentioned monomer compound in the styrene / (meth) acrylic resin is preferably in the range of 0.5 to 20% by mass with respect to the total amount of the resin.
The weight average molecular weight (Mw) of the styrene / (meth) acrylic resin is preferably in the range of 10,000 to 100,000.

The method for producing the styrene / (meth) acrylic resin is not particularly limited, and any polymerization initiator such as peroxide, persulfide, persulfate, and azo compound usually used for the polymerization of the above-mentioned monomer is used. , Bulk polymerization, solution polymerization, emulsion polymerization method, miniemulsion method, dispersion polymerization method and other known polymerization methods. Further, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans such as n-octyl mercaptan and mercapto fatty acid esters.

(Crystalline polyester resin)
It is preferable that the binder resin according to the present invention contains a crystalline polyester resin because it improves the flexibility of the toner matrix particles and facilitates the suitable adhesion of the silica particles, and also from the viewpoint of low temperature fixability. It is also preferable from.
In the present invention, the crystalline resin refers to a resin having a clear endothermic peak instead of a stepped endothermic change in differential scanning calorimetry (DSC). A clear endothermic peak specifically means a peak in which the half width of the endothermic peak is within 15 ° C. when measured at a temperature rise rate of 10 ° C./min in differential scanning calorimetry (DSC). do.

The melting point Tmc of the crystalline resin is preferably 60 ° C. or higher from the viewpoint of obtaining sufficient high-temperature storage stability, and preferably 85 ° C. or lower from the viewpoint of obtaining sufficient low-temperature fixability.

The melting point Tmc of the crystalline resin can be measured by DSC. Specifically, 0.5 mg of a crystalline resin sample is enclosed in an aluminum pan "KITNO.B0143013", set in a sample holder of a thermal analyzer "Diamond DSC" (manufactured by PerkinElmer), and heated and cooled. And the temperature is changed in the order of heating. During the first and second heating, the temperature is raised from room temperature (25 ° C) to 150 ° C at a heating rate of 10 ° C / min and maintained at 150 ° C for 5 minutes, and at the cooling rate of 10 ° C / min. The temperature is lowered from 150 ° C. to 0 ° C. and the temperature of 0 ° C. is maintained for 5 minutes. The temperature at the top of the endothermic peak in the endothermic curve obtained during the second heating is measured as the melting point (Tmc) of the crystalline resin.

The content of the crystalline polyester resin in the binder resin is preferably in the range of 5 to 20% by mass, preferably in the range of 7 to 15% by mass, from the viewpoint of obtaining sufficient low-temperature fixability. More preferred.
When the content is 5% by mass or more, a sufficient plasticizing effect can be obtained and the low temperature fixing property is excellent. When the content is 20% by mass or less, the thermal stability as a toner and the stability against physical stress are sufficient.

The number average molecular weight (Mn) of the crystalline polyester resin is preferably in the range of 2000 to 10000, and more preferably in the range of 3000 to 7000. Within these ranges, the strength of the fixed image is not insufficient, the crystalline resin is crushed during the stirring of the developer, and the glass transition temperature Tg of the toner is lowered due to an excessive plastic effect, so that the toner is not insufficient. Does not reduce the thermal stability of the. In addition, sharp melt property is exhibited, and low temperature fixing becomes possible.
The Mn can be obtained from the molecular weight distribution measured by gel permeation chromatography (GPC) as follows.

The sample is added in tetrahydrofuran (THF) to a concentration of 0.1 mg / mL, heated to 40 ° C. to dissolve, and then treated with a membrane filter having a pore size of 0.2 μm to prepare a sample solution. .. Using a GPC device HLC-8220GPC (manufactured by Tosoh Corporation) and a column "TSKgel SuperHZ3000" (manufactured by Tosoh Corporation), THF is flowed as a carrier solvent at a flow rate of 0.6 mL / min while maintaining the column temperature at 40 ° C. 100 μL of the prepared sample solution is injected into the GPC device together with the carrier solvent, and the sample is detected using a differential refractive index detector (RI detector). Then, the molecular weight distribution of the sample is calculated using the calibration curve measured using 10 points of monodisperse polystyrene standard particles. At this time, if a peak caused by the filter is confirmed in the data analysis, the region before the peak is set as the baseline.

The crystalline polyester resin according to the present invention is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher alcohol (polyhydric alcohol). As the crystalline polyester resin, a conventionally known crystalline polyester resin in the present technical field can be used. Examples of polyvalent carboxylic acids and polyhydric alcohols used in the preparation of crystalline polyester resins include:

《Polyvalent carboxylic acid》
Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, glutaric acid, adipic acid, speric acid, azelaic acid, sebacic acid, 1,9-nonandicarboxylic acid, 1,10-decandicarboxylic acid, and 1,12. -Adicarboxylic acids such as dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid. Examples thereof include aromatic dicarboxylic acids such as dibasic acids such as, and further, these anhydrides and lower alkyl esters thereof are also mentioned, but the present invention is not limited to this.
Examples of trivalent or higher carboxylic acids include 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid. Etc., and examples thereof include these anhydrides and their lower alkyl esters. These may be used alone or in combination of two or more.

The content of the constituent unit derived from the aliphatic dicarboxylic acid with respect to the constituent unit derived from the dicarboxylic acid in the crystalline polyester resin is preferably 50 mol% or more from the viewpoint of sufficiently ensuring the crystallinity of the crystalline polyester. It is more preferably 70 mol% or more, further preferably 80 mol% or more, and particularly preferably 100 mol%.

《Multivalent alcohol》
Specific examples of the aliphatic diol preferably used for the synthesis of crystalline polyester include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6. -Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13- Examples thereof include, but are not limited to, tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. Of these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in consideration of availability.
Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like. These may be used alone or in combination of two or more.

The content of the constituent unit derived from the aliphatic diol with respect to the constituent unit derived from the diol in the crystalline polyester resin is 50 mol% or more from the viewpoint of enhancing the low temperature fixability of the toner and the glossiness of the finally formed image. It is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 100 mol%.

The ratio of the diol to the dicarboxylic acid in the monomer of the crystalline polyester resin is 2.0 / [COOH], which is the equivalent ratio of the hydroxy group [OH] of the diol to the carboxy group [COOH] of the dicarboxylic acid. It is preferably in the range of 1.0 to 1.0 / 2.0, more preferably in the range of 1.5 / 1.0 to 1.0 / 1.5, and 1.3 / 1. It is particularly preferably in the range of 0.0 to 1.0 / 1.3.

The monomer constituting the crystalline polyester resin preferably contains 50% by mass or more of a linear aliphatic monomer, and more preferably 80% by mass or more. When an aromatic monomer is used, the melting point of the crystalline polyester resin tends to be high, and when a branched aliphatic monomer is used, the crystallinity tends to be low. Therefore, it is preferable to use a linear aliphatic monomer as the monomer.
From the viewpoint of maintaining the crystallinity of the crystalline polyester resin in the toner, it is preferable to use 50% by mass or more of the linear aliphatic monomer, and more preferably 80% by mass or more.

The crystalline polyester resin can be synthesized by polycondensing (esterifying) the polyvalent carboxylic acid and the polyhydric alcohol using a known esterification catalyst.

The catalyst that can be used for the synthesis of the crystalline polyester resin may be one or more, and examples thereof include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, Metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, germanium; phobic acid compounds; phosphoric acid compounds; and amine compounds; are included.

Specifically, examples of tin compounds include dibutyltin oxide, tin octylate, tin dioctylate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetranormal butyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium tetraacetylacetonate, titanium lactate, etc. Includes titanium chelates such as titanium triethanol aminate. Examples of germanium compounds include germanium dioxide, examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminates.

The polymerization temperature of the crystalline polyester resin is preferably in the range of 150 to 250 ° C. The polymerization time is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced as needed.

<Release agent>
The toner particles according to the present invention can contain various known waxes as a mold release agent. Examples of the wax include polyolefin waxes such as polyethylene wax and polypropylene wax, branched chain hydrocarbon waxes such as microcrystallin wax, long chain hydrocarbon waxes such as paraffin wax and sazole wax, and dialkyls such as distearyl ketone. Ketone wax, carnauba wax, montane wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol di Examples thereof include ester waxes such as stearate, tristearyl trimellitic acid and distealyl maleate, and amide waxes such as ethylenediamine behenylamide and tristealylamide trimellitic acid. In addition, these release agents may be used alone or in combination of two or more.
The content of the release agent is preferably in the range of 1 to 30 parts by mass, and more preferably in the range of 2 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

<Colorant>
The toner particles according to the present invention may contain a known colorant as a colorant.
Specifically, examples of the colorant contained in the yellow toner include C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185 and the like. These can be used alone or in combination of two or more.
Examples of the colorant contained in the magenta toner include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222 and the like. These can be used alone or in combination of two or more.
Examples of the colorant contained in the cyan toner include C.I. I. Pigment Blue 15: 3 and the like.
Examples of the colorant contained in the black toner include carbon black, a magnetic material, and titanium black. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black and the like.
As the magnetic material, for example, ferromagnets such as iron, nickel and cobalt, alloys containing these ferromagnets, compounds of ferromagnets such as ferrite and magnetite, and ferromagnets that do not contain ferromagnets but are heat-treated to make ferromagnetism. Examples thereof include the alloys shown. Examples of alloys that exhibit ferromagnetism by heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

The content of the colorant is preferably in the range of 1 to 10 parts by mass, and more preferably in the range of 2 to 9 parts by mass with respect to 100 parts by mass of the binder resin.

<Charge control agent>
The toner particles according to the present invention can contain a known charge control agent.
The charge control agent is not particularly limited as long as it is a substance capable of giving positive or negative charge by triboelectric charge, and various known positive charge control agents and negative charge control agents can be used. Examples include niglocin dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and salicylate metal salts.
The content of the charge control agent is preferably in the range of 0.01 to 30 parts by mass, and more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

<External agent>
The toner particles according to the present invention contain at least the first spherical silica particles and titanium dioxide particles as an external additive, and the average primary particle diameter based on the number of the first spherical silica particles is in the range of 20 to 55 nm. The content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.01 to 0.50% by mass.

Further, the toner particles according to the present invention preferably further contain a second spherical silica particle as an external additive. The average primary particle diameter based on the number of the second spherical silica particles is in the range of 70 to 160 nm. Since the second silica particles have a spacer effect, they are less likely to be buried in the toner particles of the first spherical silica even when stressed in the developing device, and the fluidity is further improved, so that the charge is further increased. It is presumed that it is possible to improve the start-up property and output high-quality images for a long period of time.

(Spherical silica particles)
The "spherical shape" of the first spherical silica particles and the second spherical silica particles according to the present invention means that the degree of spheroidization is 0.6 or more. More preferably, the degree of spheroidization is 0.8 or more.
In the present invention, the degree of spheroidization is the true degree of spheroidization of Wadell. That is, the degree of spheroidization is expressed by the following formula (A).
Formula (A) Degree of spheroidization = (surface area of sphere having the same volume as actual particle) / (surface area of actual particle)
Here, the "surface area of a sphere having the same volume as an actual particle" can be obtained by arithmetic calculation from the number average particle size obtained by the following method. Further, the "actual surface area of particles" can be replaced with the BET specific surface area obtained by using the "powder specific surface area measuring device SS-100" (manufactured by Shimadzu Corporation).

(Number of silica particles, average particle size)
Using a scanning electron microscope (SEM) "JSM-7401F" (manufactured by JEOL Ltd.), take an SEM photograph of the toner magnified 30,000 times, observe the SEM photograph, and observe the particles of the primary particles of the silica particles. The diameter (ferret diameter) is measured, and the total value is divided by the number to obtain the average particle size. The particle size is measured by selecting a region in the SEM image in which the total number of particles is about 100 to 200.

The first spherical silica particles and the second spherical silica particles are preferably spherical silica particles produced by the sol-gel method. Spherical silica particles produced by the sol-gel method are preferable because they have a uniform particle size (narrow particle size distribution, that is, monodisperse) as compared with fumed silica, which is a general production method.
It is preferable that the first spherical silica particles and the second spherical silica particles have a uniform particle size distribution. When the particle size distribution is uniform, the toner adheres uniformly to the surface of the toner matrix particles, so that the toner fluidity and the charge rising property are stable.

(Standard deviation of the number average particle size of spherical silica particles>
The degree of dispersion in the particle size distribution of spherical silica particles can be discussed by the standard deviation with respect to the number average particle size including aggregates. Here, the standard deviation of the number average particle size of the first spherical silica particles is preferably "number average particle size x 0.22 or less", and "number average particle size x 0.15 or less". More preferred. Similarly, the standard deviation of the number average particle size of the second spherical silica particles is preferably "number average particle size x 0.22 or less", and "number average particle size x 0.15 or less". More preferred.

The amount of the first spherical silica particles added is preferably in the range of 0.3 to 2.5 parts by mass, and 0.5 to 2.3 parts by mass with respect to 100 parts by mass of the toner base particles. Within the range is more preferable. When the addition amount is 0.3 parts by mass or more, the adhesiveness between the toner particles and the bottle member is lowered and the bottle dischargeability is improved. When the addition amount is 2.5 parts by mass or less, it is possible to suppress the desorption of spherical silica particles from the toner particles, the charge amount is stable even in continuous printing at a high image density, and a high-quality image is formed. be able to.
The amount of the second spherical silica particles added is preferably in the range of 0.3 to 0.7 parts by mass, preferably 0.4 to 0.5 parts by mass with respect to 100 parts by mass of the toner base particles. The range of is more preferable.

(Titanium dioxide particles)
The toner particles according to the present invention contain titanium dioxide particles as an external additive. The content of the titanium dioxide particles with respect to the total amount of the toner base particles is in the range of 0.01 to 0.50% by mass, more preferably in the range of 0.10 to 0.40% by mass. When the content of the titanium dioxide particles is in the range of 0.01 to 0.50% by mass with respect to the total amount of the toner matrix particles, it is possible to achieve both charge stability and charge rise during continuous printing. By setting the content to 0.01% by mass or more, the effect of improving the rising property of charging can be effectively obtained. Further, since it contains only a small amount of titanium dioxide particles of 0.50% by mass or less, it is possible to suppress the deterioration of the charging performance of the carrier particles caused by the adhesion of the titanium dioxide particles to the carrier particles, and as a result, continuous printing. Even when doing so, the charging performance can be stabilized.

(Other external additives)
In addition to the above-mentioned first spherical silica particles, second spherical silica particles and titanium dioxide particles, the external additive according to the present invention contains conventionally known metal oxide particles for the purpose of controlling fluidity and chargeability. Can be used. Examples thereof include alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles. These may be used alone or in combination of two or more.

Further, homopolymers such as styrene and methyl methacrylate and organic particles such as these copolymers may be used as an external additive.

The amount of these other external additives added needs to be smaller than that of the first spherical silica particles and the second spherical silica particles according to the present invention, and is 0.1 to 2.0 with respect to the total amount of the toner matrix particles. It is preferably in the range of% by mass, more preferably in the range of 0.1 to 1.6% by mass.

(Hydrophobic treatment)
The metal oxide particles used as the external additive according to the present invention are preferably those whose surface has been hydrophobized with a known surface treatment agent such as a coupling agent.
As the surface treatment agent, dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane and the like are preferable.

Further, silicone oil can also be used as the surface treatment agent. Specific examples of the silicone oil include, for example, an organosiloxane oligomer, octamethylcyclotetrasiloxane, a cyclic compound such as decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane, or linear or linear or cyclic compounds. Branched organosiloxanes can be mentioned. Further, a highly reactive silicone oil having a modifying group introduced into the side chain, one end, both ends, one side chain end, both side chain ends and the like may be used. Examples of the modifying group include, but are not limited to, an alkoxy group, a carboxy group, a carbinol group, a higher fatty acid modification, a phenol group, an epoxy group, a methacryl group, an amino group and the like. Further, for example, a silicone oil having several kinds of modifying groups such as amino / alkoxy modification may be used.

Further, dimethyl silicone oil, the above-mentioned modified silicone oil, and other surface treatment agents may be used for mixing treatment or combined treatment. Examples of the treatment agent to be used in combination include a silane coupling agent, a titanate-based coupling agent, an aluminate-based coupling agent, various silicone oils, fatty acids, fatty acid metal salts, esterified products thereof, rosinic acid and the like. ..

It is also possible to use a lubricant as an external additive to further improve the cleanability and transferability. For example, salts of zinc stearic acid, aluminum, copper, magnesium, calcium, etc., salts of zinc, manganese, iron, copper, magnesium, etc. of oleic acid, salts of zinc, copper, magnesium, calcium, etc. of palmitate, linoleic acid. Examples thereof include salts of zinc, calcium and the like, and metal salts of higher fatty acids such as zinc of ricinolic acid and salts of calcium and the like.

<Form of toner matrix particles>
The toner matrix particles may have a so-called single-layer structure, or may have a core-shell structure (a form in which a resin forming a shell layer is aggregated and fused on the surface of the core particles). It is also preferable that the material has a core-shell structure in that the low temperature fixing property becomes better.
The core-shell structure is not limited to a structure in which the shell layer completely covers the core particles. For example, the shell layer does not completely cover the core particles, and the core particles are exposed in places. Including those that are.
Further, from the viewpoint of improving the chargeability in a high temperature and high humidity environment, in the toner of the present invention, the crystalline polyester resin is not exposed on the surface of the toner matrix particles, is contained inside the toner matrix particles, and is amorphous. It is preferable that the sex resin is exposed on the surface of the toner matrix particles. The morphology of the toner matrix particles of such a toner can be controlled by the carbon number of the polyvalent carboxylic acid component and the polyhydric alcohol component forming the crystalline polyester resin. Further, as will be described later, when the toner matrix particles are produced by the emulsification aggregation method, the morphology of the toner matrix particles can also be controlled by the timing of addition of each resin or the like.

The morphology of the toner matrix particles described above (cross-sectional structure of the core-shell structure and the location of the crystalline polyester resin) is determined by using known means such as a transmission electron microscope (TEM) and a scanning probe microscope (SPM). It is possible to confirm.

<Average circularity of toner matrix particles>
The average circularity of the toner matrix particles is preferably in the range of 0.935 to 0.995, more preferably in the range of 0.945 to 0.990, and of 0.955 to 0.980. It is more preferably within the range. If the average circularity is within such a range, the individual toner matrix particles are less likely to be crushed, the amount of charge is stable, and the image quality is high.
The average circularity can be measured using, for example, a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation).

[Toner manufacturing method]
The method for producing the toner according to the present invention is not particularly limited, and a known method can be adopted, but an emulsion polymerization aggregation method or an emulsion aggregation method can be preferably adopted.
In the emulsion polymerization aggregation method preferably used in the method for producing a toner according to the present invention, a dispersion liquid of binder resin particles (hereinafter, also referred to as “binding resin particles”) produced by the emulsion polymerization method is used as a colorant. Particles (hereinafter, also referred to as "colorant particles") are mixed with a dispersion liquid and a dispersion liquid of a release agent such as wax, and the toner matrix particles are aggregated until they have a desired particle size, and further between the binder resin particles. This is a method of producing toner matrix particles by controlling the shape by fusing the particles.

Further, in the emulsification / aggregation method preferably used as a method for producing a toner according to the present invention, a binder resin solution dissolved in a solvent is dropped into a poor solvent to obtain a resin particle dispersion liquid, and the resin particle dispersion liquid and the colorant dispersion liquid are obtained. And a release agent dispersion such as wax are mixed, aggregated until the desired toner matrix particles have a diameter, and the shape is controlled by fusing between the binder resin particles to control the shape of the toner matrix particles. It is a manufacturing method.

Further, the toner matrix particles having a core-shell structure can also be obtained by the emulsification polymerization aggregation method. Specifically, the toner matrix particles having a core-shell structure are first obtained from the binder resin particles for the core particles and the colorant. The particles of the above are aggregated, associated, and fused to prepare core particles, and then the binder resin particles for the shell layer are added to the dispersion liquid of the core particles, and the binder resin particles for the shell layer are added to the surface of the core particles. Can be obtained by aggregating and fusing the particles to form a shell layer that covers the surface of the core particles.

<Method of adding external additive>
The method of adding the external additive to the toner matrix particles is not particularly limited, and examples thereof include a dry method in which the external additive is added as a powder to the dried toner matrix particles and mixed.
As the mixing device for the external additive, various known mixing devices such as a turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used. For example, when a Henschel mixer is used, the peripheral speed of the tip of the stirring blade is preferably in the range of 30 to 80 m / s, and the mixture is stirred and mixed at 20 to 50 ° C. for about 10 to 30 minutes.

[Two-component developer for electrostatic latent image development]
The two-component developer for electrostatic latent image development of the present invention (hereinafter, also simply referred to as a two-component developer or a developer) contains the toner for electrostatic latent image development of the present invention and carrier particles.
Although the two-component developer has been described, the toner of the present invention can also be used as a magnetic or non-magnetic one-component developer.

(Core particle)
The carrier particles are preferably those in which a resin coating layer is formed on the surface of the core material particles.
As the core material particles, magnetic particles made of a metal such as iron, ferrite or magnetite, or a conventionally known material such as an alloy between the metal and a metal such as aluminum or lead can be used, and ferrite particles are particularly preferable.
Further, as the carrier particles, in addition to coated carrier particles in which a resin coating layer is formed on the surface of core material particles such as magnetic particles, dispersed carrier particles obtained by dispersing magnetic fine powder in a binder resin may be used. good.

The median diameter (D ₅₀ ) based on the volume of the core material particles is generally in the range of 10 to 500 μm, preferably in the range of 30 to 100 μm.
The volume-based median diameter (D ₅₀ ) of the core material particles was measured by a wet method using a laser diffraction type particle size distribution measuring device “HEROS KA” (manufactured by Nippon Laser Co., Ltd.). Specifically, first, an optical system having a focal position of 200 mm is selected, and the measurement time is set to 5 seconds. Then, the magnetic particles for measurement are added to a 0.2 mass% sodium dodecyl sulfate aqueous solution and dispersed for 3 minutes using an ultrasonic cleaning machine "US-1" (manufactured by AS ONE Co., Ltd.) to prepare a sample dispersion for measurement. A few drops are supplied to "HEROS KA", and the measurement is started when the sample concentration gauge reaches the measurable range. A cumulative distribution was created from the small diameter side of the obtained particle size distribution with respect to the particle size range (channel), and the particle size with a cumulative particle size of 50% was defined as the volume-based median diameter (D ₅₀ ).

(Resin coating layer)
The resin coating layer according to the present invention preferably contains a copolymer formed by using an alicyclic (meth) acrylate monomer.
Further, in the present invention, "(meth) acrylate" means acrylate or methacrylate.
By using the alicyclic (meth) acrylate monomer, the hygroscopicity can be reduced and the decrease in the amount of charge at high temperature and high humidity can be suppressed. In addition, it has an appropriate mechanical strength, and the surface of the carrier particles is refreshed by the film being worn as a coating material.
Further, the copolymerization ratio (mass ratio) of the alicyclic (meth) acrylate monomer constituting the copolymer is preferably 50% or more.

The alicyclic (meth) acrylate monomer is a cycloalkyl group having 5 to 8 carbon atoms from the viewpoints of mechanical strength, environmental stability of charge amount (small environmental difference in charge amount), polymerizability and availability. It is preferable to have. The alicyclic (meth) acrylate monomer is at least one selected from the group consisting of cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate and cyclooctyl (meth) acrylate. It is preferable to have. Above all, it is preferable to contain cyclohexyl (meth) acrylate from the viewpoint of mechanical strength and environmental stability of the amount of charge.

The exposed area ratio of the core material particles on the surface of the carrier particles is preferably in the range of 10.0 to 18.0%. When the exposed area ratio is 10.0% or more, the resistance value of the carrier particles does not become too high, and a high-quality image can be output at the initial stage and after continuous printing. When the exposed area ratio is 18.0% or less, the adhesion of carrier particles to the electrostatic latent image carrier (electrophotographic photosensitive member) can be suppressed, and the image quality in continuous printing does not deteriorate.
The exposed portion of the core material particles on the surface of the carrier particles is measured by measuring the coverage of the coating resin on the core material particles by XPS measurement (X-ray photoelectron spectroscopy measurement) by the following method.
K-Alpha manufactured by Thermo Fisher Scientific is used as the XPS measuring device, and Al monochrome X-rays are used as the X-ray source, and the acceleration voltage is set to 7 kV and the emission current is set to 6 mV. , The main element (usually carbon) constituting the coating resin and the main element (usually iron) constituting the core material particles are measured.

The ratio of toner particles (toner concentration) to the total of carrier particles and toner particles is preferably in the range of 4.0 to 8.0% by mass. When the ratio of the toner particles is in the range of 4.0 to 8.0% by mass, the amount of charge of the toner particles becomes appropriate, and the image quality at the initial stage and after continuous printing becomes better.

The two-component developer according to the present invention can be produced by mixing carrier particles and toner particles using a mixing device. Examples of the mixing device include a Henschel mixer, a Nauter mixer, and a V-type mixer.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Preparation of amorphous polyester resin particle dispersion>
<< Preparation of amorphous polyester resin (A1) >>
・ 40 mol parts of bisphenol A ethylene oxide 2.2 mol addition ・ 60 mol part of bisphenol A propylene oxide 2.2 mol addition ・ 60 mol part of dimethyl terephthalate ・ 15 mol part of dimethyl fumarate ・ 20 mol part of dodecenyl succinic acid anhydride -Trimeric acid anhydride 5 mol parts In a reaction vessel equipped with a stirrer, thermometer, condenser and nitrogen gas introduction tube, among the above monomers, monomers other than dimethyl fumarate and trimellitic acid anhydride and dioctyl acid. 0.25 parts by mass of tin was added to a total of 100 parts by mass of the above monomers. Then, after reacting at 235 ° C. for 6 hours under a nitrogen gas stream, the temperature was lowered to 200 ° C., dimethyl fumarate and trimellitic acid anhydride were added, and the reaction was carried out for 1 hour. The temperature was raised to 220 ° C. over 5 hours and polymerized under a pressure of 10 kPa until the desired molecular weight was obtained to obtain a pale yellow transparent amorphous polyester resin (A1).
The amorphous polyester resin (A1) had a weight average molecular weight of 35,000, a number average molecular weight of 8,000, and a glass transition temperature (Tg) of 56 ° C.

<< Preparation of amorphous polyester resin particle dispersion liquid (a1) >>
Next, 200 parts by mass of the amorphous polyester resin, 100 parts by mass of methyl ethyl ketone, 35 parts by mass of isopropyl alcohol, and 7.0 parts by mass of a 10% by mass aqueous ammonia solution were placed in a separable flask, and then sufficiently mixed and dissolved. Ion-exchanged water was dropped at a liquid feeding rate of 8 g / min using a liquid feeding pump while heating and stirring at 40 ° C., and the dropping was stopped when the liquid feeding amount reached 580 parts by mass. Then, the solvent was removed under reduced pressure to obtain an amorphous polyester resin particle dispersion. Ion-exchanged water was added to the dispersion to adjust the solid content to 25% by mass to prepare an amorphous polyester resin particle dispersion (a1). The volume-based medium diameter ( _D50 ) of the amorphous polyester resin particles in this dispersion was measured by Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.) and found to be 156 nm.

<Preparation of amorphous vinyl resin particle dispersion liquid (b1)>
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introduction device, 5.0 parts by mass of an anionic surfactant (Dowfax manufactured by Dow Chemical Co., Ltd.) and 2500 parts by mass of ion-exchanged water were added. The internal temperature was raised to 75 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.
Next, a solution prepared by dissolving 18.0 parts by mass of potassium persulfate (KPS) in 342 parts by mass of ion-exchanged water was added, and the liquid temperature was adjusted to 75 ° C. Further, 903.0 parts by mass of styrene (St), 282.0 parts by mass of n-butyl acrylate (BA) and 12.0 parts by mass of acrylic acid (AA), 3.0 parts by mass of 1,10-decanediol diacrylate and A monomer mixed solution consisting of 8.1 parts by mass of dodecanethiol was added dropwise over 2 hours.

After the completion of the dropping, the mixture was polymerized by heating and stirring at 75 ° C. for 2 hours to obtain an amorphous vinyl resin dispersion. Ion-exchanged water was added to the dispersion to adjust the solid content to 25% by mass to prepare a dispersion (b1) of amorphous vinyl resin (B1) particles. The volume-based median diameter ( _D50 ) of the amorphous vinyl resin (B1) particles in this dispersion was measured with Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.) and found to be 160 nm.
The amorphous vinyl resin (B1) had a glass transition temperature (Tg) of 52 ° C., a weight average molecular weight (Mw) of 38,000, and a number average molecular weight (Mn) of 15,000.

<Preparation of crystalline polyester resin particle dispersion>
<< Production of crystalline polyester resin (C1) >>
50 mol parts of dodecane diic acid 50 mol parts of 1,6-hexanediol The above monomer was placed in a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas introduction tube, and the inside of the reaction vessel was replaced with dry nitrogen gas. .. Next, 0.25 parts by mass of titanium tetrabutoxide (Ti (On-Bu) ₄ ) was added to a total of 100 parts by mass of the above-mentioned monomers. After stirring and reacting at 170 ° C. for 3 hours under a nitrogen gas stream, the temperature was further raised to 210 ° C. over 1 hour, the temperature inside the reaction vessel was reduced to 3 kPa, and the reaction was stirred and reacted under reduced pressure for 13 hours. , A crystalline polyester resin (C1) was obtained.
The crystalline polyester resin (C1) had a weight average molecular weight of 25,000, a number average molecular weight of 8500, and a melting point of 71.8 ° C.

<< Preparation of crystalline polyester resin particle dispersion liquid (c1) >>
Next, 200 parts by mass of the crystalline polyester resin (C1), 120 parts by mass of methyl ethyl ketone, and 30 parts by mass of isopropyl alcohol were placed in a separable flask, which were mixed and dissolved at 60 ° C., and then a 10% by mass aqueous ammonia solution was added. 8 parts by mass was dropped. The heating temperature was lowered to 67 ° C., and the mixture was dropped at a liquid feeding rate of 8 g / min using an ion-exchanged water feeding pump while stirring, and when the feeding amount reached 580 parts by mass, the dropping of ion-exchanged water was stopped. .. Then, the solvent was removed under reduced pressure to obtain a crystalline polyester resin particle dispersion. Ion-exchanged water was added to the dispersion to adjust the solid content to 25% by mass to prepare a crystalline polyester resin particle dispersion (c1). The volume-based medium diameter ( _D50 ) of the crystalline polyester resin particles in this dispersion was measured with Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.) and found to be 198 nm.

<Preparation of mold release agent particle dispersion (W1)>
-Paraffin wax (HNP0190 made by Nippon Seiro, melting temperature 85 ° C)
270 parts by mass / anionic surfactant (Neogen RK manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 13.5 parts by mass (active ingredient 60%, 3% with respect to mold release agent)
21.6 parts by mass of ion-exchanged water After mixing the above materials and dissolving the mold release agent with a pressure discharge homogenizer (Gorin homogenizer manufactured by Gorin) at an internal liquid temperature of 120 ° C, the dispersion pressure is 5 MPa for 120 minutes. Subsequently, the dispersion treatment was carried out at 40 MPa for 360 minutes and cooled to obtain a dispersion liquid. Ion-exchanged water was added to the dispersion to adjust the solid content to 20%, and this was used as the release agent particle dispersion (W1). The volume-based median diameter (D ₅₀ ) of the release agent particles in the release agent particle dispersion liquid (W1) was 215 nm.

<Preparation of colorant particle dispersion liquid (1)>
-Carbon black (manufactured by Cabot, Legal (registered trademark) 330) 100 parts by mass-Anionic surfactant (Neogen SC manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 15 parts by mass-Ion-exchanged water 400 parts by mass Mix the above components and homogenizer. After pre-dispersing for 10 minutes with (Ultratarax, manufactured by IKA), dispersion treatment is performed for 30 minutes at a pressure of 245 MPa using a high-pressure impact disperser Ultimizer (manufactured by Sugino Machine Limited), and an aqueous dispersion of black colorant particles. Got Ion-exchanged water was further added to the obtained dispersion to adjust the solid content to 15% by mass to prepare a black colorant particle dispersion (1). The volume-based median diameter (D ₅₀ ) of the colorant particles in this dispersion was measured using Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.) and found to be 110 nm.

<Preparation of toner matrix particles (1)>
≪Agglomeration / fusion process and aging process≫
-Atypical polyester resin particle dispersion liquid (a1) 1008 parts by mass-Atypical vinyl resin particle dispersion liquid (b1) 32 parts by mass-Crystalular polyester resin particle dispersion liquid (c1) 160 parts by mass-Release agent particle dispersion Liquid (W1) 8 parts by mass, colorant particle dispersion liquid (1) 187 parts by mass, anionic surfactant (Doufax2A1 20% aqueous solution) 40 parts by mass, ion exchange water 1500 parts by mass

The above materials were placed in a 4 liter reaction vessel equipped with a thermometer, a pH meter and a stirrer, and 1.0% nitric acid was added at a temperature of 25 ° C. to adjust the pH to 3.0. Then, 100 parts by mass of an aqueous solution of aluminum sulfate (aggregator) having a concentration of 2% was added over 30 minutes while dispersing at 3000 rpm with a homogenizer (Ultratalax T50 manufactured by IKA). After completion of the dropping, the mixture was stirred for 10 minutes to thoroughly mix the raw material and the flocculant.

After that, a stirrer and a mantle heater are installed in the reaction vessel, and while adjusting the rotation speed of the stirrer so that the slurry is sufficiently agitated, the temperature rise rate is 0.2 ° C./min up to a temperature of 40 ° C., 40. After the temperature exceeded ° C., the temperature was raised at a heating rate of 0.05 ° C./min, and the particle size was measured every 10 minutes with a Coulter Multisizer 3 (aperture diameter 100 μm, manufactured by Beckman Coulter). The temperature was maintained when the volume-based median diameter reached 3.9 μm, and a premixed mixture of the following materials was added over 20 minutes.
-Amorphous polyester resin particle dispersion liquid (a1) 400 parts by mass-Anionic surfactant (Doufax2A1 20% aqueous solution) 15 parts by mass

Then, after holding at 50 ° C. for 30 minutes, 8 parts by mass of a 20% solution of EDTA (ethylenediaminetetraacetic acid) was added to the reaction vessel, and then a 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the raw material dispersion solution to 9. Adjusted to 0.0. Then, while adjusting the pH to 9.0 every 5 ° C., the temperature was raised to 85 ° C. at a heating rate of 1 ° C./min and maintained at 85 ° C.

≪Cooling process≫
Then, when the shape coefficient reaches 0.970, the toner matrix particle dispersion liquid (1) is cooled at a temperature lowering rate of 10 ° C./min using a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation). Got

≪Filtration / cleaning process and drying process≫
Then, it was filtered and washed with ion-exchanged water. Then, it was dried at 40 ° C. to obtain toner matrix particles (1). The volume-based median diameter of the obtained toner matrix particles (1) was 4.0 μm, and the average circularity was 0.971.

<Preparation of toner matrix particles (2)>
In the "aggregation / fusion step and aging step" of the preparation of the toner matrix particles (1), the temperature was maintained when the volume-based median diameter reached 4.9 μm, and the following premixed materials were added. ..
400 parts by mass of amorphous polyester resin particle dispersion liquid (a1) 15 parts by mass of anionic surfactant (Doufax2A1 20% aqueous solution) The production method other than the above is the same as the production method of the toner matrix particles (1). , Toner matrix particles (2) were prepared. The volume-based median diameter of the obtained toner matrix particles (2) was 5.0 μm, and the average circularity was 0.969.

<Preparation of toner matrix particles (3)>
In the "aggregation / fusion step and aging step" of the preparation of the toner matrix particles (1), the temperature was maintained when the volume-based median diameter reached 2.9 μm, and the following premixed materials were added. ..
400 parts by mass of amorphous polyester resin particle dispersion liquid (a1) 15 parts by mass of anionic surfactant (Doufax2A1 20% aqueous solution) The production method other than the above is the same as the production method of the toner matrix particles (1). , Toner matrix particles (3) were prepared. The volume-based median diameter of the obtained toner matrix particles (3) was 3.0 μm, and the average circularity was 0.972.

<Preparation of toner matrix particles (4)>
In the "aggregation / fusion step and aging step" of the preparation of the toner matrix particles (1), the temperature was maintained when the volume-based median diameter reached 2.7 μm, and the following premixed materials were added. ..
400 parts by mass of amorphous polyester resin particle dispersion liquid (a1) 15 parts by mass of anionic surfactant (Doufax2A1 20% aqueous solution) The production method other than the above is the same as the production method of the toner matrix particles (1). , Toner matrix particles (4) were prepared. The volume-based median diameter of the obtained toner matrix particles (4) was 2.8 μm, and the average circularity was 0.971.

<Preparation of toner matrix particles (5)>
In the "aggregation / fusion step and aging step" of the preparation of the toner matrix particles (1), the temperature was maintained when the volume-based median diameter reached 5.1 μm, and the following premixed materials were added. ..
400 parts by mass of amorphous polyester resin particle dispersion liquid (a1) 15 parts by mass of anionic surfactant (Doufax2A1 20% aqueous solution) The production method other than the above is the same as the production method of the toner matrix particles (1). , Toner matrix particles (5) were prepared. The volume-based median diameter of the obtained toner matrix particles (5) was 5.2 μm, and the average circularity was 0.972.

<Preparation of toner matrix particles (6)>
In the "aggregation / fusion step and aging step" of the toner matrix particles (1), the material contained in the 4-liter reaction vessel was changed as follows.
・ Atypical vinyl resin particle dispersion (b1) 1040 parts by mass ・ Crystalline polyester resin particle dispersion (c1) 160 parts by mass ・ Colorant particle dispersion (1) 187 parts by mass ・ Anionic surfactant (Doufax2A1 20) % Aqueous solution) 40 parts by mass, 1500 parts by mass of ion-exchanged water The production method other than the above was the same as the production method of the toner matrix particles (1), and the toner matrix particles (6) were obtained. The volume-based median diameter of the obtained toner matrix particles (6) was 4.0 μm, and the average circularity was 0.971.

<Preparation of the first spherical silica particles (1-1)>
(1) To a 3 liter reactor equipped with a stirrer, a dropping funnel and a thermometer, 945 parts by mass of methanol, 45 parts by mass of 28% ammonia water and 135 parts by mass of water were added and mixed. The temperature of this solution was adjusted to 35 ° C., and 405 parts by mass of tetramethoxysilane was added dropwise over 6 hours while stirring, and after the addition, stirring was continued for 1 hour to hydrolyze to obtain a suspension of silica particles. ..
(2) 4.8 parts by mass of methyltrimethoxysilane was added dropwise to this aqueous suspension at room temperature to hydrophobize the surface of the silica particles.
(3) The dispersion thus obtained was heated to 80 ° C. and methanol water was distilled off. 130 parts by mass of hexamethyldisilazane was added to the obtained dispersion at room temperature, heated to 60 ° C. and reacted for 9 hours to trimethylsilylate the silica particles. Then, the solvent was distilled off under reduced pressure to prepare silica particles (1-1).
When the number average primary particle size and standard deviation of the first spherical silica particles (1-1) obtained by the above method were measured, the number average primary particle size (D ₅₀ ) was 40 nm and the standard deviation was 5 nm. there were.

<Preparation of the first spherical silica particles (1-2) to (1-5)>
In the preparation of the first spherical silica particles (1-1), the number average is obtained by controlling the mass ratio, reaction temperature, stirring speed, and supply speed of alkoxysilane, ammonia, alcohol, and water in the hydrolysis and polycondensation steps. The particle size was adjusted to prepare the first spherical silica particles (1-2) to (1-5) shown in Table I below.

<Preparation of the second spherical silica particles (2-1) to (2-5)>
In the preparation of the first spherical silica particles (1-1), the number average is obtained by controlling the mass ratio, reaction temperature, stirring speed, and supply speed of alkoxysilane, ammonia, alcohol, and water in the hydrolysis and polycondensation steps. The second spherical silica particles (2-1) to (2-5) shown in Table I below were prepared by adjusting the particle size.

<< Preparation of toner particles 1 >>
(External additive addition process)
To 100 parts by mass of the toner matrix particles (1), 1.0 part by mass of the first spherical silica particles (1-1) and 0.50 parts by mass of the second spherical silica particles (2-1) were added. Further, hydrophobic titanium dioxide particles (HMDS treated, hydrophobicity 55%, average primary particle diameter = 20 nm based on the number of particles) were added in an amount of 0.3 parts by mass with respect to 100 parts by mass of the toner base particles (1). Toner particles 1 were prepared by mixing with a hydrophobic mixer for 20 minutes.

<< Preparation of toner particles 2-8 and 21-23 >>
In the preparation of the toner particles 1, the amount of titanium dioxide particles added was changed as shown in Table II to prepare the toner particles 2 to 8 and 21 to 23.

<< Preparation of toner particles 9, 10, 24 and 25 >>
In the preparation of the toner particles 1, the toner particles 9, 10, 24 and 25 were prepared by changing to the types of the first spherical silica particles shown in Table II, respectively.

<< Preparation of toner particles 11-14 >>
In the preparation of the toner particles 1, the toner particles 11 to 14 were prepared by changing to the types of the second spherical silica particles shown in Table II.

<< Preparation of toner particles 15 to 19 >>
In the production of the toner particles 1, the toner particles 15 to 19 were produced in the same manner except that the toner matrix particles 1 were changed to the types of the toner matrix particles shown in Table II.

<< Preparation of toner particles 20 >>
In the preparation of the toner particles 1, as shown in Table II, the toner particles 20 were prepared without adding the second spherical silica particles.

<< Preparation of toner particles 26 >>
Non-spherical silica particles (number average particle size 40 nm, spheroidization degree 0.5, 1.10 parts by mass and second spherical silica particles (2- 1) Toner particles 26 were prepared by adding 1.50 parts by mass and mixing with a Henshell mixer for 20 minutes.

<Preparation of carrier particles>
(Preparation of core material particles 1)
Weigh the raw materials so that MnO: 35 mol%, MgO: 14.5 mol%, Fe ₂ O ₃ : 50 mol% and SrO: 0.5 mol%, mix with water, and grind for 5 hours with a wet media mill. A slurry was obtained.

The obtained slurry was dried with a spray dryer to obtain spherical particles. After adjusting the particle size of the particles, the particles were heated at 950 ° C. for 2 hours and calcined in a rotary kiln. After crushing with a dry ball mill using stainless beads with a diameter of 0.3 cm for 1 hour, polyvinyl alcohol (PVA) as a binder was added in an amount of 0.8% by mass based on the solid content, and water and a dispersant were further added to form a diameter. It was ground for 25 hours using 0.5 cm zirconia beads. Then, granulation was performed by a spray dryer, dried, and kept at a temperature of 1050 ° C. for 20 hours in an electric furnace for main firing.
Then, it was crushed, further classified to adjust the particle size, and then the low magnetic force product was separated by magnetic dressing to obtain core material particles 1. The volume-based median diameter (D ₅₀ ) of the core material particles 1 was 28.0 μm.

(Preparation of coating resin 1)
Cyclohexyl methacrylate and methyl methacrylate were added to an aqueous solution of 0.3% by mass of sodium benzenesulfonate at a "copolymerization ratio (mass ratio) = 50: 50" to 0.5% by mass of the total amount of the monomers. A coating resin 1 was prepared by adding a corresponding amount of potassium persulfate, performing emulsion polymerization, and drying by spray drying. The weight average molecular weight of the obtained coating resin 1 was 500,000.

(Preparation of coating resin 2)
In the preparation of the coating resin 1, the coating resin 2 was produced in the same manner except that cyclohexyl methacrylate and methyl methacrylate were changed to "copolymerization ratio (mass ratio) = 80:20".

(Preparation of carrier particle 1)
100 parts by mass of the core material particles 1 prepared above as core material particles and 4.5 parts by mass of the coating resin 1 are put into a high-speed stirring mixer with horizontal stirring blades, and the peripheral speed of the horizontal rotary blade is 8 m. After mixing and stirring at 22 ° C. for 15 minutes under the condition of / sec, mixing at 120 ° C. for 50 minutes and coating the surface of the core material particles with the action of mechanical impact force (mechanochemical method). , The mixture was cooled to room temperature to prepare "carrier particles 1".

(Preparation of carrier particles 2)
In the production of the carrier particles 1, the carrier particles 2 were produced in the same manner except that the coating resin 1 was changed to the coating resin 2.

<Preparation of developer>
<Preparation of developer 1>
The toner particles 1 and the carrier particles 1 prepared as described above were mixed so as to have a toner concentration of 9% by mass to prepare a developer 1. A V-type mixer (manufactured by Tokuju Kosakusho Co., Ltd.) was used as a mixer, and the mixture was mixed at 25 ° C. for 30 minutes.

<Preparation of developing agents 2-26>
Developers 2 to 26 were prepared in the same manner as in the above-mentioned preparation of the developer 1 except that the combination of the toner particles and the carrier particles was shown in Table IV below.

<Evaluation method>
As an evaluation device, a commercially available digital full-color multifunction device "bizhub PRO (registered trademark) C6500" (manufactured by Konica Minolta Co., Ltd.) was used, and each of the developers prepared above was sequentially loaded, and the environment was low temperature and low humidity (temperature 10 ° C.). , Humidity 20%), 100,000 sheets were printed on A4 size high-quality paper (65 g / m ² ) to form a strip-shaped solid image with a print rate of 5% as a test image. Then, the following evaluation was performed. The results of each evaluation are shown in Table IV below.

(Evaluation of charge rise)
The charge rising property was evaluated by the change in solid image density (density followability).
The change in the solid image density was measured by measuring the density of the solid image at the time of printing 1 sheet, 100 sheets, 500 sheets, and 2000 sheets, and measuring the density change.
As for the change in the solid image density, the image density (absolute density) of the 100th and 2000th solid image portions was measured, and it was judged that the difference between the two images was 0.1 or less.
The image density was measured with a reflection densitometer RD-918 manufactured by Macbeth. The image density is the absolute density.

(Evaluation of stability of charging performance)
The stability of the charging performance was evaluated by the amount of toner scattered.
The amount of toner scattered in the image forming apparatus was measured as follows. First, after printing 100,000 sheets with the above evaluation device, the inside of the machine was once cleaned. After that, 10,000 sheets of character images with a printing rate of 5% were printed on A4 size high-quality paper, and 10,000 sheets were printed with 10% character images, and then 10,000 sheets were printed with 20% character images, for a total of 10,000 sheets. We printed 30,000 sheets. The amount of toner scattered was the total amount of toner scattered on the image forming apparatus main body, the cartridge, and the toner filter there.
After printing 30,000 sheets, the toner scattered around the developed area such as the top lid of the cartridge is sucked and the mass is measured, the mass of the toner adhering to the toner filter is measured, and the sum of these is called the toner scattering amount (g). did. A toner scattering amount of 1 g or less was regarded as acceptable.

As shown in the results of Table IV above, in the image formation with the two-component developer using the toner of the present invention, the charge rising property and the stability of the charging performance are excellent even in a low temperature and low humidity environment, and in a low temperature and low humidity environment. It was found that a high-quality image can be formed even when continuous printing is performed with.
On the other hand, in the image formation with the two-component developer using the toner of the comparative example, it was inferior to any of the items.

Claims (7)

Toner for electrostatic latent image development that contains toner particles having an external additive on the surface of the toner matrix particles.
The median diameter based on the volume of the toner matrix particles is in the range of 3.0 to 5.0 μm.
As the external additive, at least the first spherical silica particles , the second spherical silica particles, and the titanium dioxide particles are contained.
The average primary particle diameter based on the number of the first spherical silica particles is in the range of 20 to 55 nm.
The average primary particle diameter based on the number of the second spherical silica particles is in the range of 70 to 160 nm.
The content of the first spherical silica particles with respect to the total amount of the toner matrix particles is in the range of 0.3 to 2.5% by mass.
The content of the second spherical silica particles with respect to the total amount of the toner matrix particles is in the range of 0.3 to 0.7% by mass.
A toner for electrostatic latent image development, wherein the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.01 to 0.50% by mass. The toner for electrostatic latent image development according to claim 1, wherein the content of the titanium dioxide particles with respect to the total amount of the toner matrix particles is in the range of 0.10 to 0.40% by mass. The toner for electrostatic latent image development according to claim 1 or 2 , wherein an amorphous polyester resin is contained as the binder resin of the toner matrix particles. The invention according to any one of claims 1 to 3, wherein the binder resin of the toner matrix particles contains an amorphous polyester resin, an amorphous vinyl resin, and a crystalline polyester resin. Toner for electrostatic latent image development. A two-component developer for electrostatic latent image development, which comprises the toner for electrostatic latent image development according to any one of claims 1 to 4 and carrier particles. The carrier particles have a resin coating layer on the surface, and the carrier particles have a resin coating layer on the surface.
The two-component developer for electrostatic latent image development according to claim 5 , wherein the resin coating layer contains a copolymer formed by using an alicyclic (meth) acrylate monomer. The two-component development for electrostatic latent image development according to claim 6 , wherein the copolymerization ratio (mass ratio) of the alicyclic (meth) acrylate monomer constituting the copolymer is 50% or more. Agent.