JP6089467B2 - Toner for developing electrostatic image and image forming method - Google Patents

Description

  The present invention relates to an electrostatic image developing toner used as a non-magnetic one-component developer and an image forming method using the electrostatic image developing toner.

  Conventionally, as a non-magnetic one-component developing method, for example, a toner conveying member, a toner layer regulating member and a toner replenishing auxiliary member are provided, and a toner conveying member and a toner layer regulating member, and a toner conveying member and a toner replenishing auxiliary member are provided. A developing device having a configuration in which the members are in contact with each other supplies an electrostatic charge image developing toner (hereinafter also simply referred to as “toner”) as a non-magnetic one-component developer to the surface of the electrostatic latent image carrier. And developing the latent image. In this system, there is a problem in that the toner fluidity changes due to long-term use, and toner conveyance unevenness easily occurs, and as a result, image unevenness occurs. Further, depending on long-term use, the toner is fused to the toner conveying member and the toner layer regulating member, particularly in a high temperature and high humidity environment, and there is a problem that fogging occurs.

As a technique for improving toner fluidity and environmental characteristics, Patent Document 1 discloses the use of toner in which fluorine-containing resin particles are shelled on the surface.
However, when the toner is used as a non-magnetic one-component developer, there is a problem in that a highly negatively charged charge is likely to occur on the toner surface due to the influence of fluorine, and a sleeve ghost is generated.

Japanese Patent No. 3994686

  The present invention has been made in consideration of the above-described circumstances. The object of the present invention is to suppress the occurrence of image unevenness and fog and to prevent sleeve ghosting when used as a non-magnetic one-component developer. An object of the present invention is to provide an electrostatic image developing toner and an image forming method capable of stably forming a high-quality image over a long period of time by suppressing the occurrence of the above.

The electrostatic image developing toner of the present invention is an electrostatic image developing toner used as a non-magnetic one-component developer.
A shell layer containing a copolymer resin formed by a polymerizable monomer having fluorine and a polymerizable monomer having an acidic polar group is formed on the core particle containing the binder resin. Consists of toner particles and external additives,
The external additive contains at least silica fine particles and composite inorganic fine particles made of an inorganic compound containing magnesium and aluminum.

In the electrostatic charge image developing toner of the present invention, the composite inorganic fine particles have a magnesium to aluminum content ratio [Mg (atm%) / Al (atm%)] of 1 to 4, and an electrostatic resistance of 1 × 10 ^10. ˜1 × 10 ¹³ Ω · cm and a number average primary particle size of 50 to 1000 nm are preferable.

  In the electrostatic image developing toner of the present invention, it is preferable that the external additive further contains titanium-containing oxide fine particles.

  In the electrostatic image developing toner of the present invention, the composite inorganic fine particles are preferably contained in a ratio of 0.02 to 1.0% by mass with respect to the total mass of the electrostatic image developing toner.

  In the electrostatic image developing toner of the present invention, it is preferable that the binder resin according to the core particle is made of a styrene-acrylic copolymer resin.

  The image forming method of the present invention is characterized by using the toner for developing an electrostatic image described above.

  According to the toner for developing an electrostatic charge image of the present invention, the shell layer contains a copolymer resin of a polymerizable monomer having fluorine and a polymerizable monomer having an acidic polar group. In addition, silica fine particles can be suppressed by using at least silica fine particles and composite inorganic fine particles made of an inorganic compound containing magnesium (Mg) and aluminum (Al) as an external additive. In order to further suppress the occurrence of image unevenness and to prevent negative charge-up on the toner surface because the composite inorganic fine particles are positively charged. The occurrence of sleeve ghost can be suppressed. From the above, according to the electrostatic image developing toner of the present invention, a high-quality image can be stably formed over a long period of time when used as a non-magnetic one-component developer.

It is the schematic for description which shows the structure of the apparatus used when measuring the static resistance which concerns on this invention. FIG. 3 is a cross-sectional view illustrating an example of the configuration of a full-color image forming apparatus that uses the toner of the present invention as a nonmagnetic one-component developer. FIG. 5 is an explanatory cross-sectional view illustrating an example of a configuration of a developing cartridge for a one-component developer.

  Hereinafter, the present invention will be described in detail.

[Toner for electrostatic image development]
The toner of the present invention is a toner used as a non-magnetic one-component developer, and a polymerizable monomer having a fluorine and a polymerizable monomer having an acidic polar group on a core particle containing a binder resin. It comprises toner particles formed with a shell layer containing a copolymer resin formed of a monomer and an external additive. The toner particles according to the present invention are fine particles made of a resin containing a copolymer resin (hereinafter also referred to as “shell resin”) on the surface of core particles containing a binder resin, for example, by salting out / fusion. A core-shell structure is formed by fusing (hereinafter also referred to as “shell resin fine particles”).

[Shell layer]
The shell layer constituting the toner particles according to the present invention includes a polymerizable monomer having fluorine (hereinafter also referred to as “polymerizable monomer A”) and a polymerizable monomer having an acidic polar group (hereinafter referred to as “polymerizable monomer A”). , “Polymerizable monomer B”) and a shell resin containing a copolymer resin (hereinafter, also referred to as “specific copolymer resin”). In addition to the specific copolymer resin, the shell resin may contain other resins such as a styrene-acrylic copolymer resin, a polyester resin, and a urethane resin.
The content ratio of the specific copolymer resin in the shell resin is preferably 20 to 100% by mass and more preferably 50 to 100% by mass in 100% by mass of the shell resin.
When the content ratio of the specific copolymer resin in the shell resin is within the above range, it is possible to reliably suppress the occurrence of image unevenness and fog.
On the other hand, when the content ratio of the specific copolymer resin in the shell resin is less than 20% by mass, sufficient negative chargeability due to fluorine cannot be obtained, and image unevenness and fog may occur.

  As the polymerizable monomer A having fluorine, a monomer represented by the following general formula (1) is preferably used.

In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having at least one fluorine. The alkyl group having at least one fluorine represented by R _^2, - (CH ²⁾ alkyl group represented by _n -Rf is preferably used. Among these, n is preferably an integer of 1 to 10, more preferably 2 to 4. Rf is preferably a fluoroalkyl group having 1 to 21 carbon atoms, and more preferably a linear or branched fluoroalkyl group or perfluoroalkyl group having 6 to 10 carbon atoms.

Specific examples of the polymerizable monomer A represented by the general formula (1) are shown below.
Compound _{(A-1): CH 2} = C (CH 3) CO 2 CH 2 CF 3
Compound _{(A-2): CH 2} = C (CH 3) CO 2 CH 2 (CF 2) 2 H
Compound _{(A-3): CH 2} = C (CH 3) CO 2 CH 2 CF 2 CF 3
Compound _{(A-4): CH 2} = CHCO 2 CH 2 CF 3
Compound _{(A-5): CH 2} = CHCO 2 CH 2 (CF 2) 2 H
Compound _{(A-6): CH 2} = CHCO 2 CH 2 CF 2 CF 3
Compound (A-7): β- (perfluorooctylethyl) acrylate compound (A-8): β- (perfluorooctylethyl) methacrylate compound (A-9): β- (perfluoroisononylethyl) acrylate compound (A-10): β- (perfluoroisononylethyl) methacrylate These may be used alone or in combination of two or more.

  Examples of the polymerizable monomer B having an acidic polar group include an α, β-ethylenically unsaturated compound having a carboxyl group and an α, β-ethylenically unsaturated compound having a sulfonic acid group.

  Examples of the α, β-ethylenically unsaturated compound having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester, And metal salts such as Na and Zn.

  Examples of the α, β-ethylenically unsaturated compound having a sulfonic acid group include sulfonated styrene and its Na salt, allyl sulfosuccinic acid, octyl allyl sulfosuccinate, and Na salt thereof.

  Among the above, methacrylic acid and acrylic acid are particularly preferable. In addition, the compounds described above can be used alone or in combination of two or more.

  In the present invention, the specific copolymer resin is preferably formed using the other polymerizable monomer C together with the polymerizable monomer A and the polymerizable monomer B.

  Examples of the vinyl polymerizable monomer C include styrene monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, and the like.

  Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, and pn. -Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4- Examples thereof include styrenic monomers such as dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of the (meth) acrylic acid ester monomer include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, Examples include butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

  Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, vinyl benzoate, and examples of vinyl ether monomers include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, and vinyl phenyl ether. It is done.

Of these, butyl acrylate and methyl methacrylate are particularly preferred.
In addition, the compounds described above can be used alone or in combination of two or more.

  The composition ratio of the polymerizable monomer A, the polymerizable monomer B, and the other vinyl polymerizable monomer C is the polymerizable monomer A, the polymerizable monomer B, and the other vinyl polymerization. Based on the total mass of the polymerizable monomer C, the polymerizable monomer A is preferably 20 to 80% by mass, more preferably 25 to 70% by mass, and the polymerizable monomer B is 2 to 20% by mass, and more preferably 3 to 12% by mass.

The concentration of the polymer A containing the polymerization component of the polymerizable monomer A may increase from the surface of the shell resin fine particles to the inside, or may decrease from the surface of the shell resin fine particles to the inside.
When producing toner particles, it is particularly preferable that the concentration of the polymer A increases from the surface of the shell resin fine particles to the inside from the viewpoint of enhancing the adhesion between the core particles and the shell layer.

  The change in the concentration of the polymer A containing the polymerization component of the polymerizable monomer A is specifically determined by adding a polymerization initiator to the dispersion obtained by mixing the polymerizable monomers A, B and C at a certain ratio. This can be achieved by starting the polymerization and preparing a seed, and then dropping the polymerization monomer A, B and C by changing the ratio of the polymerizable monomers A, B and C to complete the polymerization.

  For example, after forming a core part of shell resin fine particles by adding a polymerization initiator solution to a polymerizable monomer dispersion containing a polymerizable monomer A and a polymerizable monomer B, the polymerizable monomer Shell resin fine particles can be produced by dropping a polymerizable monomer not containing A or a main component to form a shell portion.

  Here, the polymer A, which is a polymer component of the polymerizable monomer A, may be a homopolymer of the polymerizable monomer A or a copolymer with other polymerizable monomers.

  The shell resin fine particles preferably have a discontinuous layer like a core-shell structure. Here, the resin constituting the resin layer of the core part or the resin layer of the shell part is composed of 20 to 80% by mass of the polymerization component of the polymerizable monomer A and 2 polymerization components of the polymerizable monomer B as the constituent components. It is preferable to contain in the ratio of -20 mass%.

  The concentration of the polymer A containing the polymerization component of the polymerizable monomer A is higher or lower on the surface or inside of the shell resin fine particles, or a discontinuous layer such as a core-shell structure. The composition analysis of the sample having the above can be measured by performing analysis by X-ray photoelectron spectroscopy from the surface of the fine particle to the inside of the fine particle while etching from the surface of the fine particle.

  The softening point of the specific copolymer resin is preferably 80 to 170 ° C., more preferably 90 to 120 ° C., and the glass transition point is preferably 35 to 80 ° C., more preferably 40 to 60 ° C.

In the present invention, the softening point of a specific copolymer resin is measured by a flow tester.
Specifically, a pellet having a load of 200 N, a die diameter of 1 mm, 10 mm, and a height of 12 mm is left at 80 ° C. for 300 seconds, and then measured by a 5 mm offset method at a temperature rising rate of 6 ° C./min.

In the present invention, the glass transition point of a specific copolymer resin is measured by a differential calorimetric analysis method, for example, using a DSC curve.
Specifically, it was measured using DSC-7 (manufactured by Perkin Elmer), and as the measurement conditions, the temperature was raised / cooled as it was left at 0 ° C. for 1 minute, and then 200 ° C./min. The temperature is raised to ° C. (first temperature raising process). Next, after standing at 200 ° C. for 1 minute, it is cooled to 0 ° C. under the condition of 10 ° C./min (first cooling process). Next, after standing at 0 ° C. for 1 minute, the temperature is raised to 200 ° C. under the condition of 10 ° C./min (second temperature raising process). The onset method value measured in the second temperature raising process, that is, the intersection of the peak base line and the peak maximum slope line was defined as the glass transition point.

  The specific copolymer resin preferably has a number average molecular weight (Mn) of 1000 to 100,000 and a weight average molecular weight (Mw) of 2000 to 1000000 as measured by gel permeation chromatography. Furthermore, it is preferable that molecular weight distribution (Mw / Mn) is 1.5-100, More preferably, it is 1.8-70.

[Core particles]
The core particles constituting the toner particles according to the present invention contain a binder resin, and may contain a colorant or may not contain a colorant.
When toner containing a colorant is used, it is preferably contained in the core particles.

Examples of the binder resin include various known thermoplastic resins such as vinyl resins such as styrene-acrylic copolymer resins, polyester resins, polyamide resins, and polyurethane resins. You may use these individually by 1 type or in combination of 2 or more types. In the toner of the present invention, it is preferable to use a styrene-acrylic copolymer resin from the viewpoint of adhesion to the shell layer.
Moreover, as a manufacturing method of a core particle, from the viewpoint of the uniformity of a particle diameter, a chemical method is preferable instead of a pulverization method.

The binder resin preferably has a glass transition point of 30 to 60 ° C, more preferably 30 to 50 ° C. Moreover, it is preferable that a softening point is 80-110 degreeC, More preferably, it is 90-100 degreeC.
The glass transition point and softening point of the binder resin are measured in the same manner as described above using the binder resin as a measurement sample.

  The binder resin is composed of a high molecular weight component having a peak or a shoulder in a region having a molecular weight measured by gel permeation chromatography of 100,000 to 1,000,000 and a low molecular weight component having a peak or a shoulder in a region of 1000 to 50,000. It is preferable to contain both components, and it is more preferable to use an intermediate molecular weight resin having a peak or shoulder in the region of 15,000 to 100,000.

[Colorant]
Examples of the colorant in the case where the core particle is configured to contain a colorant include various inorganic pigments, organic pigments, and dyes. A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
These inorganic pigments can be used alone or in combination of two or more. Moreover, it is preferable that the addition amount of a pigment is 2-20 mass% with respect to binder resin, More preferably, it is 3-15 mass%.
When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.

  Conventionally known organic pigments and dyes can also be used, and specific organic pigments and dyes are exemplified below.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

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

  These organic pigments and dyes can be used alone or in combination of two or more. The addition amount of the pigment is preferably 2 to 20% by mass, more preferably 3 to 15% by mass with respect to the binder resin.

  In the present invention, the colorant may be surface-modified. A conventionally well-known thing can be used as a surface modifier, Specifically, a silane coupling agent, a titanium coupling agent, an aluminum coupling agent etc. can be used preferably. Examples of the silane coupling agent include alkoxysilanes such as methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane, siloxanes such as hexamethyldisiloxane, γ-chloropropyltrimethoxysilane, and vinyltrimethyl. Chlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureido Examples include propyltriethoxysilane. As the titanium coupling agent, for example, TTS, 9S, 38S, 41B, 46B, 55, 138S, and 238S marketed under the trade name “Plenact” manufactured by Ajinomoto Co., Inc., commercial products A manufactured by Nippon Soda Co., Ltd. -1, B-1, TOT, TST, TAA, TAT, TLA, TOG, TBSTA, A-10, TBT, B-2, B-4, B-7, B-10, TBSTA-400, TTS, TOA -30, TSDMA, TTAB, TTOP and the like. Examples of the aluminum coupling agent include “Plenact AL-M” manufactured by Ajinomoto Co., Inc.

  The addition amount of these surface modifiers is preferably 0.01 to 20% by mass, more preferably 0.1 to 5% by mass with respect to the colorant. Further, as a method for modifying the surface of the colorant, there may be mentioned a method in which a surface modifier is added to a dispersion of fine colorant particles and this system is heated to react. The colorant fine particles whose surface has been modified in this way are obtained by filtration, and after drying and filtering with the same solvent are repeated, drying is performed.

(External additive)
The external additive constituting the toner of the present invention contains at least silica fine particles and composite inorganic fine particles made of an inorganic compound containing magnesium (Mg) and aluminum (Al).

The silica fine particles constituting the external additive may be any of fumed silica produced by a dry gas phase method and sol-gel silica produced by a wet sol-gel method, and is not limited.
In the toner of the present invention, high fluidity can be imparted to the toner particles by using silica fine particles as an external additive.

The number average primary particle size of the silica fine particles is preferably 5 to 200 nm, more preferably 10 to 150 nm. Two or more types having different number average primary particle sizes may be used in combination.
The content of the silica fine particles is preferably 0.05 to 5% by mass, and more preferably 0.1 to 3% by mass with respect to the total mass of the toner.

The composite inorganic fine particles constituting the external additive are made of an inorganic compound containing magnesium (Mg) and aluminum (Al).
Since the composite inorganic fine particles in the toner of the present invention are positively charged, generation of sleeve ghost can be suppressed in order to suppress excessive charge-up of negative charge generated on the surface of the toner having fluorine.
In particular, among these composite inorganic fine particles, a double hydroxide having a layered crystal structure, so-called hydrotalcite compound, is preferable because it has good charging characteristics and can obtain a higher quality image. Can do.

Specific examples of the composite inorganic fine particles include the following.
Compound (FM-1): MgAl ₂ O ₄
Compound (FM-2): Mg ₂ (Ni) ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O
Compound (FM-3): Mg _3.5 Zn _0.5 Al ₂ (OH) ₁₂ CO ₃ .3H ₂ O
Compound (FM-4): Mg ₄ Al ₂ (OH) ₁₂ CO ₃ .3H ₂ O
Compound (FM-5): Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O
Compound (FM-6): Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O
Compound (FM-7): Mg ₁₀ Al ₂ (OH) ₂₄ CO ₃

The content ratio of the composite inorganic fine particles is preferably 0.02 to 1.0% by mass, and more preferably 0.05 to 0.80% by mass with respect to the total mass of the toner.
When the content ratio of the composite inorganic fine particles is 0.02% by mass or more, the charging characteristics and the degree of aggregation of the toner can be adjusted. Stability can be ensured.

The content ratio [Mg (atm%) / Al (atm%)] of Mg and Al in the composite inorganic fine particles is preferably 1 to 4, more preferably 1.5 to 2.5.
When the content ratio [Mg (atm%) / Al (atm%)] is within the above range, the intended charging performance can be ensured.

In the present invention, the content ratio [Mg (atm%) / Al (atm%)] is measured using a fluorescent X-ray analyzer (XRF).
An X-ray fluorescence analyzer (XRF) irradiates a sample with continuous X-rays to generate characteristic X-rays (fluorescent X-rays) unique to the elements constituting the sample. Then, the generated fluorescent X-ray is spectrally separated (spectral dispersion type) by a spectral crystal to generate a spectrum, the obtained spectrum is measured, and the constituent elements are quantitatively analyzed from the intensity.

In the fluorescent X-ray analysis method, a calibration curve is prepared with a fluorescent X-ray analyzer using composite inorganic fine particles having a known content ratio of magnesium and aluminum, and using the calibration curve, The content ratio of aluminum is obtained.
Examples of the X-ray fluorescence analyzer (XRF) include XRF-1800 (manufactured by Shimadzu Corporation) and ZSX-100E (manufactured by RIGAKU Corporation).

The determination of magnesium and aluminum by an X-ray fluorescence analyzer (XRF) can be performed, for example, by the following procedure.
(1) First, a sample for preparing a calibration curve is prepared. A known amount of magnesium hydroxide is added to 100 parts by mass of styrene powder to produce a measurement pellet for magnesium hydroxide. Similarly, a known amount of aluminum oxide is added to 100 parts by mass of styrene powder to produce a measurement pellet for aluminum oxide.
(2) Each of the produced pellets is measured with a fluorescent X-ray analyzer, and a calibration curve for magnesium and aluminum is prepared from the peak intensity obtained from each sample for magnesium hydroxide or aluminum oxide in styrene powder.
(3) Next, the composite inorganic fine particles containing magnesium and aluminum used in the present invention are measured with a fluorescent X-ray analyzer, and the obtained peak intensity is collated with a calibration curve, thereby containing magnesium and aluminum. Quantify the percentage.

  In the fluorescent X-ray analysis, rhodium (Rh) Kα ray is used as X-ray, and, for example, quantification is performed under an output condition of a tube voltage of 20 kV and a tube current of 100 mA. As the spectral crystal, known spectral crystals for magnesium and titanium can be used.

  Furthermore, a known scintillation counter or a proportion counter can be used as a detector for detecting the spectrum.

The static resistance of the composite inorganic fine particles is preferably 1 × 10 ¹⁰ to 1 × 10 ¹³ Ω · cm, more preferably 5 × 10 ^{10 to} 5 × 10 ¹² Ω · cm.
By static resistance of the composite inorganic fine particles used more than 1 × ¹⁰ 10 Ω · cm, even under high temperature and high humidity environment can charge amount suppress leakage, the use of the following 1 × 10 ¹³ Ω · cm Thus, overcharging can be suppressed even in a low temperature and low humidity environment, and environmental stability can be maintained.

  In the present invention, the static resistance of the composite inorganic fine particles is a value measured by the following procedure.

FIG. 1 is an explanatory schematic diagram showing the configuration of an apparatus used when measuring static resistance.
In FIG. 1, 1 is a load unit, 2 is a sample, 3 is the height of the sample, 4 is a main body cell, 5 is a high-voltage power supply, and 6 is a resistance measuring instrument.
In the measurement, first, the sample 2 (1 g) is put into the main body cell 4, and then the load unit 1 of 1400 g is put thereon, and the height 3 of the sample is measured in this state. Thereafter, a DC voltage of 1000 V is applied to the upper and lower electrode surfaces of the sample 2 using the high voltage power source 5, and the resistance value displayed by the resistance measuring instrument 6 after 30 seconds is read.
The area of the electrode of this measuring device is 0.968 cm ² , and the static resistance is calculated from these values by the following formula (1).
Formula (1): Static resistance = {resistance (Ω) × electrode area (cm ² )} / sample height (cm)

The number average primary particle size of the composite inorganic fine particles is preferably 50 to 1000 nm, more preferably 200 to 800 nm.
By using composite inorganic fine particles having a number average primary particle size of 50 nm to 1000 nm, it is added in a preferable state to the toner particle surface, and charging characteristics can be secured.

In the present invention, the number average primary particle size of the composite inorganic fine particles is measured by the following method.
A 30,000 times photograph of the toner is taken with a scanning electron microscope, and the photograph image is captured by a scanner. In the image processing analyzer “LUZEX AP (manufactured by Nireco)”, the external additive present on the toner particle surface of the photographic image is binarized, and the horizontal ferret diameter for 100 composite inorganic fine particles is obtained. The average value is calculated as the number average particle diameter.

The specific surface area of the composite inorganic fine particles is preferably 1.0 m ² / g or more, more preferably 5.0 to ²⁰⁰ m ² / g.

  In the present invention, the specific surface area is determined by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device “Auto Soap 1” (manufactured by Yuasa Ionics) according to the BET method, and using the BET multipoint method. This is a value obtained by calculation.

In the present invention, the silica fine particles and the composite inorganic fine particles are preferably subjected to a hydrophobizing treatment with a surface treatment agent in order to stabilize the environment.
Examples of the surface treatment agent include silane coupling agents, titanium coupling agents, higher fatty acids, and silicone oils.
Of these, silane coupling agents are preferably used, such as hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxy. Silane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltri Methoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriace Etc. may be used Kishishiran, silicone - as is N'oiru, such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenyl polysiloxane and the like.

In the toner of the present invention, it is preferable to use titanium-containing oxide fine particles together with silica fine particles and composite inorganic fine particles as an external additive from the viewpoint of stabilization of chargeability. Specific examples of the fine particles include titania fine particles and composite oxide fine particles containing silicon atoms and titanium atoms.
By adding such titanium-containing oxide fine particles, the charge amount is stabilized at an appropriate value, so that fog can be further suppressed at the end of durability.

As the titania fine particles, anatase titania, rutile titania, amorphous titania and the like can be used, and anatase titania is preferable.
The number average primary particle diameter of the titania fine particles is preferably 5 to 200 nm, more preferably 8 to 100 nm.

In the composite oxide fine particles containing silicon atoms and titanium atoms, the ratio of titanium atoms to the total amount of metal elements is preferably 80 atm% or more and 99.5 atm% or less, more preferably 90 atm% or more and 97 atm% or less. It is.
The number average primary particle size of the composite oxide fine particles is preferably 10 to 500 nm, more preferably 20 to 200 nm.

  The method for producing composite oxide fine particles containing silicon atoms and titanium atoms that can be used in the present invention is not particularly limited. For example, the gas phase method is one of typical production methods. The gas phase method is a method for producing an oxide containing silicon atoms and titanium atoms by heating and vaporizing a raw material compound containing silicon atoms and titanium atoms, and burning the obtained gas. As a method for producing composite oxide fine particles such as oxide particles containing titanium atoms and silicon atoms by a vapor phase method, for example, a method for producing a mixed oxide by high thermal decomposition disclosed in Japanese Patent No. 32025573 Etc. is one of them.

  In the case of titania fine particles or composite oxide fine particles containing silicon atoms and titanium atoms, two or more kinds of fine particles having different particle diameters and surface treatments may be added, and the addition amount is 0 with respect to the total mass of the toner. The content is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass.

In the present invention, as the external additive, in addition to these, other fine particles can be used in combination. Examples of the other fine particles include inorganic stearate compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles, and inorganic titanate compound fine particles such as strontium titanate and zinc titanate. The other inorganic fine particles preferably have a number average primary particle size of 5 to 200 nm, more preferably 8 to 100 nm.
The content of other inorganic fine particles is preferably 0.01 to 5% by mass, and more preferably 0.05 to 3% by mass with respect to the total mass of the toner.

From the viewpoint of environmental stability, titania fine particles, composite oxide fine particles containing silicon atoms and titanium atoms, and other fine particles are surface treated with silane coupling agents, titanium coupling agents, higher fatty acids, silicone oils, etc. It is preferable that
Of these, silane coupling agents are preferably used, such as hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxy. Silane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltri Methoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriace Kishishiran like can be used, and silicone - as is N'oiru, such as dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenyl polysiloxane can be used.

[Toner Production Method]
The toner of the present invention can be produced by various known methods. Since the shell layer can be uniformly formed on the surface of the core particles, the binder resin fine particles and the colorant fine particles dispersed in the aqueous medium are used. It is preferable to manufacture by the emulsion polymerization aggregation method in which toner particles are obtained by agglomerating and fusing the core particles to form core particles and aggregating and fusing the shell resin fine particles on the surface of the core particles.

When the toner of the present invention is produced by an emulsion polymerization aggregation method, a production example of a toner containing a colorant is specifically shown.
(1-1) A shell resin fine particle dispersion preparing step of forming a shell resin fine particle by a shell resin in an aqueous medium to prepare a dispersion in which the shell resin fine particle is dispersed;
(1-2) A binder resin polymerization step in which a binder resin fine particle is formed by polymerization in an aqueous medium to prepare a dispersion in which the binder resin fine particle is dispersed;
(1-3) Colorant fine particle dispersion preparation step for preparing a dispersion in which colorant fine particles are dispersed in an aqueous medium.
(2) a core particle forming step of aggregating binder resin fine particles and colorant fine particles in an aqueous medium to form core particles;
(3) Shell formation in which shell resin fine particles are added to an aqueous medium in which core particles are dispersed to aggregate and fuse the shell resin fine particles on the surface of the core particles to form toner particles having a core-shell structure. Process,
(4) An aging step of adjusting the shape of the toner particles by aging with heat energy;
(5) a cleaning step of separating the toner particles from the toner particle dispersion (aqueous medium) and removing the surfactant from the toner particles;
(6) a drying step of drying the washed toner particles;
(7) An external additive adding step of adding an external additive to the dried toner particles.

  In the present invention, the “aqueous medium” refers to a medium comprising 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

(1-1) Shell resin fine particle dispersion preparation step The shell resin fine particles are preferably prepared by an emulsion polymerization method or a mini-emulsion polymerization method, and more preferably a chain represented by the following general formula (2) during polymerization. By using a transfer agent, the molecular weight and molecular weight distribution of the shell resin can be adjusted to a preferred range.

Hereinafter, the emulsion polymerization method or the mini-emulsion polymerization method will be described.
In the emulsion polymerization method, an emulsifier (hereinafter also referred to as “surfactant”) having a monomer (hereinafter also referred to as “monomer”) concentration higher than a critical micelle formation concentration (hereinafter referred to as “CMC”). In the presence of a resin, it is emulsified and dispersed by a mechanical dispersing means such as a homogenizer, then mainly a water-soluble polymerization initiator is added, polymerized to form resin fine particles, and then the resin fine particles of a desired size by association. It is a method of manufacturing.

  The mini-emulsion polymerization method is one form of the emulsion polymerization method and emulsifies with an emulsifier concentration of CMC or less. The polymerization initiator used at this time may be either water-soluble or oil-soluble. For example, an oil-soluble polymerization initiator or a functional compound is allowed to coexist with a polymerizable monomer, and in the presence of an emulsifier having a concentration of CMC or lower. By mechanically dispersing and polymerizing, molecular diffusion of functional additives and the like in the monomer particles is suppressed, and the polymerization proceeds only in the monomer oil droplets. Resin fine particles contained reliably in the particles can be obtained.

[Chain transfer agent]
Formula ^{(2): HS-R 3} -COOR 4
In the general formula (2), R ³ represents a divalent group having 1 to 10 carbon atoms, and R ⁴ represents an alkyl group having 2 to 15 carbon atoms.

In the general formula (2), examples of R ³ include an alkylene group, an alkenylene group, an alkynylene group, and the like. Specific examples include an ethylene group, a propylene group, a butylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group. Group, octamethylene group, hexamethylene group, ethylethylene group, propenylene group, vinylene group and the like. These substituents may be unsubstituted or may further have a substituent.

In the general formula (2), as R ⁴ , for example, a linear or branched alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, iso-pentyl group, 2-ethyl group) -Hexyl group, octyl group, decyl group, etc.), alkenyl group (for example, 2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 4-hexenyl group) and aralkyl groups (for example, benzyl group, phenethyl group, etc.).

  Examples of the chain transfer agent represented by the general formula (2) include thioglycolic acid esters and 3-mercaptopropionic acid esters. Specifically, as thioglycolic acid esters, ethyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, thioglycolic acid Decyl, dodecyl thioglycolate, thioglycolate of ethylene glycol, thioglycolate of neopentyl glycol, thioglycolate of trimethylolpropane, thioglycolate of pentaerythritol, thioglycolate of sorbitol . Examples of 3-mercaptopropionic acid esters include ethyl ester, octyl ester, decyl ester, dodecyl ester, pentaerythritol tetrakis ester, 3-mercaptopropionic acid ester of ethylene glycol, 3-mercaptopropionic acid ester of neopentyl glycol, trimethylol Examples include propane 3-mercaptopropionate, pentaerythritol 3-mercaptopropionate, sorbitol 3-mercaptopropionate, and the like. Among these, 3-mercaptopropionic acid esters are particularly preferably used, and in particular, n-octyl-3-mercaptopropionic acid ester.

  As the usage-amount of the chain transfer agent represented by the said General formula (2), it is preferable that it is 0.01-5 mass% with respect to a polymerizable monomer, More preferably, it is 0.03-3 mass %.

  In the emulsion polymerization method and miniemulsion polymerization method described above, a polymerization initiator is used to start the polymerization reaction. As the polymerization initiator, a water-soluble initiator is preferable. For example, a persulfate (for example, potassium persulfate, ammonium persulfate, etc.), an azo compound (for example, 4,4′-azobis-4-cyanovaleric acid and And salts thereof, 2,2′-azobis (2-amidinopropane) salts, etc.) and peroxide compounds. Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature is lowered, and the polymerization time can be shortened.

  The polymerization temperature is not particularly limited as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator. However, it is also possible to perform polymerization at room temperature or higher by using a polymerization initiator that is started at room temperature in combination with hydrogen peroxide / reducing agent (such as ascorbic acid).

  The reaction temperature varies depending on the monomer used, the type of polymerization initiator, and the like, but is usually preferably in the range of 30 to 80 ° C. Moreover, although reaction time is until the time of a monomer component lose | disappearing, 3 to 20 hours are preferable normally. In addition, pH which superposes | polymerizes is performed in a weakly acidic atmosphere, and 4-6 are preferable. The solid content is 25% or more, preferably 35% or more.

The average particle diameter of the shell resin fine particles obtained in this shell resin fine particle dispersion preparation step is preferably in the range of 30 to 400 nm, for example, in terms of volume-based median diameter.
The volume-based median diameter is measured using “UPA-150” (manufactured by Microtrack).

[Surfactant]
A dispersion stabilizer is preferably added to the aqueous medium in order to prevent aggregation of dispersed fine particles.
As the dispersion stabilizer, various known surfactants such as a cationic surfactant, an anionic surfactant, and a nonionic surfactant can be used.
Specific examples of the cationic surfactant include dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl anonium bromide and the like.
Specific examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, norylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, styrylphenyl poly Examples thereof include oxyethylene ether and monodecanoyl sucrose.
Specific examples of the anionic surfactant include aliphatic soaps such as sodium stearate and sodium laurate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene (2) sodium lauryl ether sulfate and the like. it can.
The above surfactants can be used singly or in combination of two or more as desired.

(1-2) Binder Resin Polymerization Step In this binder resin polymerization step, resin fine particles related to the binder resin are formed and used for the core particle formation step.
Specifically, the resin fine particles related to the binder resin are used as necessary for the polymerizable monomer for forming the binder resin in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less. Add a monomer solution in which toner components such as wax and charge control agent are dissolved or dispersed, add mechanical energy to form droplets, and then add a water-soluble radical polymerization initiator. The polymerization reaction is allowed to proceed in the droplet. Note that an oil-soluble polymerization initiator may be contained in the droplet. In such a binder resin polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin.

  The binder resin fine particles to be formed in this binder resin polymerization step may have a structure of two or more layers made of resins having different compositions. In this case, an emulsion polymerization process (first-stage polymerization according to a conventional method) The polymerization initiator and the polymerizable monomer are added to the dispersion liquid of the first resin fine particles prepared by the above method, and the system is polymerized (second-stage polymerization).

  When using a surfactant in the binder resin polymerization step, use the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step, for example. Can do.

In addition to the binder resin and the colorant, the toner particles according to the present invention may contain an internal additive such as a wax, a charge control agent, and a magnetic powder as necessary as a toner constituent. Such an internal additive can be introduced into the toner particles by, for example, dissolving or dispersing in advance in the monomer solution for forming the binder resin in the binder resin polymerization step.
In addition, such an internal additive is prepared by separately preparing a dispersion of internal additive fine particles consisting of only the internal additive, and aggregating the internal additive fine particles together with the resin fine particles and the colorant fine particles in the core particle forming step. Although it can be introduced into the toner particles, it is preferable to adopt a method in which it is introduced in advance in the binder resin polymerization step.

〔wax〕
Examples of the wax include low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, hydrocarbon waxes such as paraffin wax, carnauba wax, pentaerythritol behenate, behenyl behenate, And ester waxes such as behenyl acid. These can be used individually by 1 type or in combination of 2 or more types.
As the wax, it is preferable to use a wax having a melting point of 50 to 95 ° C. from the viewpoint of reliably obtaining low-temperature fixability and releasability of the toner.
The content ratio of the wax is preferably 2 to 20% by mass, more preferably 3 to 18% by mass, and further preferably 4 to 15% by mass with respect to the total amount of the resin constituting the toner.

[Charge control agent]
As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, fourth compounds. Examples include quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
Examples of the method of incorporating the charge control agent in the toner particles include the same method as the method of incorporating the offset preventing agent described above.
The content ratio of the charge control agent is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass with respect to the total amount of the resin constituting the toner.

(Polymerization initiator)
As the polymerization initiator used in the binder resin polymerization step, the same ones as described above can be used.

[Chain transfer agent]
In the binder resin polymerization step, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the binder resin. As the chain transfer agent, the same ones as described above can be used.

The average particle size of the binder resin fine particles obtained in this binder resin polymerization step is preferably in the range of, for example, 30 to 400 nm in terms of volume-based median diameter.
The volume-based median diameter is measured using “UPA-150” (manufactured by Microtrack).

(1-3) Colorant fine particle dispersion preparation step The colorant fine particle dispersion can be prepared by dispersing a colorant in an aqueous medium. The colorant dispersion treatment is preferably performed in a state where the surfactant concentration in the aqueous medium is not less than the critical micelle concentration (CMC) since the colorant is uniformly dispersed. Various known dispersers can be used as a disperser used for the dispersion treatment of the colorant.

The dispersion diameter of the colorant fine particles in the colorant fine particle dispersion prepared in the colorant fine particle dispersion preparing step is preferably 10 to 300 nm in terms of volume-based median diameter.
The volume-based median diameter of the colorant fine particles in the colorant fine particle dispersion is measured with an electrophoretic light scattering photometer “ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)”.

  When a surfactant is used in this colorant fine particle dispersion preparation step, the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step, for example, is used. Can be used.

(2) Core particle formation step In this core particle formation step, fine particles of other toner constituent components such as wax and charge control agent can be aggregated together with the binder resin fine particles and the colorant fine particles, if necessary. .

  As a specific method for agglomerating and fusing the binder resin fine particles and the colorant fine particles, a flocculant is added to the aqueous medium so as to have a critical aggregation concentration or higher, and then at a glass transition point or higher of the binder resin fine particles. And by heating to a temperature equal to or higher than the melting peak temperature (° C.) of these mixtures, the salting out of the fine particles such as the binder resin fine particles and the colorant fine particles proceeds, and at the same time, the fusion is advanced in parallel. This is a method in which when the particles have grown to a desired particle size, an aggregation terminator is added to stop the particle growth, and heating is continued to control the particle shape as necessary.

  In this method, the time allowed to stand after addition of the flocculant is shortened as much as possible, and immediately heated to a temperature above the glass transition point of the binder resin fine particles and above the melting peak temperature (° C.) of these mixtures. It is preferable to do. The reason for this is not clear, but depending on the standing time after salting out, the aggregation state of the particles may fluctuate and the particle size distribution may become unstable, and the surface properties of the fused particles may vary. This is because there is concern about the occurrence. The time until this temperature rise is usually preferably within 30 minutes, and more preferably within 10 minutes. Moreover, it is preferable that it is 1 degree-C / min or more as a temperature increase rate. The upper limit of the heating rate is not particularly specified, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of fusion. Furthermore, after the reaction system reaches a temperature equal to or higher than the glass transition point, it is important to continue the fusion by maintaining the temperature of the reaction system for a certain time. Thereby, the growth and fusion of the core particles can be effectively advanced, and the durability of the toner particles finally obtained can be improved.

[Flocculant]
The flocculant used in the core particle forming step is not particularly limited, but a material selected from metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as alkali metal salts such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; and trivalent metal salts such as iron and aluminum. Etc. Specific metal salts can include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, and the like. It is particularly preferable to use a divalent metal salt. These can be used individually by 1 type or in combination of 2 or more types.

  When using a surfactant in the core particle forming step, it is possible to use, for example, the same surfactant as the surfactant that can be used in the above-mentioned shell resin fine particle dispersion preparation step. it can.

As for the particle size of the core particles obtained in this core particle forming step, for example, the volume-based median diameter (D ₅₀ ) is preferably 2 to 9 μm, more preferably 4 to 7 μm.
The volume-based median diameter of the core particles is measured by “Coulter Multisizer 3” (manufactured by Coulter Beckman).

(3) Shelling step In this shelling step, shell resin fine particles are added to the dispersion of core particles to aggregate and fuse the shell resin fine particles on the surface of the core particles, and a shell layer is formed on the surface of the core particles. The toner particles are formed by coating.
Specifically, the dispersion of the core particles is added to the dispersion of the shell resin fine particles while maintaining the temperature in the core particle formation step, and the shell resin fine particles are slowly removed over several hours while continuing the heating and stirring. The toner particles are formed by aggregating and fusing the surfaces of the core particles with a shell layer having a thickness of 100 to 300 nm on the surface of the core particles. The heating and stirring time is preferably 1 to 7 hours, particularly preferably 3 to 5 hours.

(4) Ripening step The shape of the toner particles in the toner can be made uniform to some extent by controlling the heating temperature in the core particle forming step and the shelling step, but in order to further make the shape uniform, the ripening step Go through.
This aging step is controlled by controlling the heating temperature and time so that the surface of the toner particles formed with a constant particle size and a narrow distribution has a smooth but uniform shape. Specifically, the heating temperature is lowered in the core particle forming step and the shelling step to suppress the progress of fusion between the resin fine particles to promote leveling, and in this aging step, the heating temperature is lowered. In addition, the toner particles are controlled so as to have a desired average circularity, that is, a surface having a uniform shape by extending the time.

(5) Washing step to (6) Drying step The washing step and the drying step can be performed by employing various known methods.

(7) External additive addition step This external additive addition step is a step of preparing a toner by adding and mixing the external additive to the dried toner particles.
As the external additive, at least silica fine particles and composite inorganic fine particles are preferably used, and titania fine particles are further preferably used.

  Examples of the method for adding the external additive include a dry method in which the external additive is added in powder form to the dried toner particles. Examples of the mixing device include mechanical mixing devices such as a Henschel mixer and a coffee mill. .

[Average toner particle size]
The average particle diameter of the toner of the present invention is preferably, for example, 3 to 10 μm in volume-based median diameter (D ₅₀ ). This particle size can be controlled by the concentration of the flocculant used, the amount of organic solvent added, the fusing time, and the polymer composition when the emulsion polymerization aggregation method is employed.
When the volume-based median diameter is in the above range, for example, a very minute dot image at a level of 1200 dpi (dpi; number of dots per inch (2.54 cm)) can be faithfully reproduced.

In the present invention, the volume-based median diameter of the toner is measured using a measuring apparatus in which a computer system equipped with data processing software “Software V3.51” is connected to “Multisizer 3” (manufactured by Beckman Coulter).・ It is calculated.
Specifically, 0.02 g of toner is added to 20 mL of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing toner particles). Then, ultrasonic dispersion was performed for 1 minute to prepare a toner particle dispersion, and this toner particle dispersion was placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Inject with a pipette until the displayed concentration of the measuring device is 8%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measuring apparatus, the frequency value is calculated by setting the number of measured particle counts to 25000 and the aperture diameter to 100 μm, and the particle diameter of 50% from the larger volume integrated fraction is the volume-based median diameter.

[Average circularity of toner]
In the toner of the present invention, the arithmetic average value of the circularity represented by the following formula (T) is 0.850 to 0.990 from the viewpoint of improving the transfer efficiency of the individual toner particles constituting the toner. Is preferred.
Formula (T): Circularity = perimeter of perfect circle having projection area equivalent to particle projection image / perimeter of particle projection image

In the present invention, the average circularity of the toner is a value measured using “FPIA-2100” (manufactured by Sysmex).
Specifically, the toner particles are moistened with an aqueous surfactant solution, and ultrasonic dispersion is performed for 1 minute. After dispersion, HPFP detection is performed in the measurement condition HPF (high magnification imaging) mode using “FPIA-2100”. Measurement is performed at appropriate concentrations of several thousand to 10,000. Within this range, reproducible measurement values can be obtained.

  According to the toner as described above, the shell layer contains a copolymer resin composed of a polymerizable monomer having fluorine and a polymerizable monomer having an acidic polar group, thereby causing image unevenness and fogging. Further, by using at least silica fine particles and composite inorganic fine particles made of an inorganic compound containing magnesium (Mg) and aluminum (Al) as external additives, the silica fine particles are even higher. Since fluidity is imparted, the occurrence of image unevenness is surely suppressed, and the composite inorganic fine particles are positively charged. Occurrence can be suppressed. From the above, according to the toner of the present invention, high-quality images can be stably formed over a long period of time when used as a non-magnetic one-component developer.

(Developer)
The toner of the present invention is used as a non-magnetic one-component developer.

[Image forming apparatus]
The toner of the present invention can be used in a general electrophotographic image forming method. As an image forming apparatus in which such an image forming method is performed, for example, a photosensitive member that is an electrostatic latent image carrier, A charging means for applying a uniform potential to the surface of the photoconductor by corona discharge having the same polarity as that of the toner, and an electrostatic latent image by performing image exposure on the surface of the uniformly charged photoconductor based on image data. An exposure means for forming an image; a developing means for conveying the toner to the surface of the photoreceptor to visualize the electrostatic latent image to form a toner image; and passing the toner image through an intermediate transfer member as necessary. For example, a transfer unit that transfers to a transfer material and a fixing unit that fixes a toner image on the transfer material can be used.

The toner of the present invention can be suitably used at a relatively low temperature where the fixing temperature (the surface temperature of the fixing member) is 100 to 200 ° C.
Furthermore, the toner of the present invention can be suitably used for a high-speed machine in which the linear velocity of the electrostatic latent image carrier is 100 to 500 mm / sec.

  FIG. 2 is an explanatory sectional view showing an example of the configuration of a full-color image forming apparatus using the toner of the present invention as a non-magnetic one-component developer.

  In the full-color image forming apparatus shown in FIG. 2, a charging brush 111 as charging means for uniformly charging the surface of the photosensitive drum 10 to a predetermined potential around the photosensitive drum 10 to be rotationally driven, and the photosensitive drum. A cleaner 112 that removes toner remaining on the drum 10 is provided.

  Further, there is provided a laser scanning optical system 20 which is an exposure means for scanning and exposing the photosensitive drum 10 charged by the charging brush 111 with a laser beam. The laser scanning optical system 20 includes a laser diode, a polygon mirror, and an fθ optical system. It is a well-known device having a built-in element, and print data for each of yellow, magenta, cyan, and black is transferred from the host computer to the control unit. The laser scanning optical system 20 sequentially outputs the laser beam as a laser beam based on the print data for each color, scans and exposes the surface of the photosensitive drum 10, and thereby the static image for each color on the photosensitive drum 10. Electro latent images are sequentially formed.

  Further, the full-color developing cartridge 30 that is a developing unit that supplies toner of each color to the photosensitive drum 10 on which the electrostatic latent image is formed in this way and performs full-color development, has yellow, magenta, Four developing cartridges 31Y, 31M, 31C, and 31Bk for each color containing cyan and black non-magnetic one-component toners are provided. The developing cartridges 31Y, 31M, 31M, and 31B are rotated about the support shaft 33. 31C and 31Bk are guided to positions facing the photosensitive drum 10.

  Further, in each of the developing cartridges 31Y, 31M, 31C, and 31Bk in the full-color developing cartridge 30, for example, as shown in FIG. 3, the toner is formed on the outer peripheral surface of a developer carrier (developing roller) 25 that rotates and conveys the toner. A regulating member is pressed (contacted), and the toner regulating member regulates the amount of toner conveyed by the developing roller 25 and charges the conveyed toner.

  As described above, each time an electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20, the full-color developing cartridge 30 is rotated about the support shaft 33 as described above. The developing cartridges 31Y, 31M, 31C, and 31Bk containing the corresponding color toners are sequentially guided to positions facing the photosensitive drum 10, and the developing rollers 25 in the developing cartridges 31Y, 31M, 31C, and 31Bk are moved. The charged toner of each color is sequentially supplied onto the photosensitive drum 10 in which the electrostatic latent images of each color are sequentially formed as described above in contact with or without contact with the photosensitive drum 10. Development is to be performed.

  Further, an endless intermediate transfer belt 40 that is rotationally driven is provided as an intermediate transfer member at a position downstream of the full-color developing cartridge 30 in the rotation direction of the photosensitive drum 10. The photosensitive drum 10 is rotated in synchronization with the photosensitive drum 10. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 so as to come into contact with the photosensitive drum 10, and a portion of the support roller 42 that supports the intermediate transfer belt 40 includes A secondary transfer roller 43 is rotatably provided, and the transfer material S such as recording paper is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43.

  Further, a cleaner 50 that scrapes off the toner remaining on the intermediate transfer belt 40 is provided in a space between the full-color developing cartridge 30 and the intermediate transfer belt 40 so as to be able to contact and separate from the intermediate transfer belt 40. .

  The sheet feeding means 60 that guides the transfer material S to the intermediate transfer belt 40 also feeds the transfer material S stored in the sheet feed tray 61 one by one. It is composed of a paper roller 62 and a timing roller 63 that feeds the transfer material S fed in synchronization with the image formed on the intermediate transfer belt 40 between the intermediate transfer belt 40 and the secondary transfer roller 43. In this way, the transfer material S sent between the intermediate transfer belt 40 and the secondary transfer roller 43 is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43, and the toner image is transferred from the intermediate transfer belt 40. The transfer material S is pressed and transferred.

  On the other hand, the transfer material S on which the toner image is pressed and transferred as described above is guided to the fixing unit 70 by the conveying unit 66 constituted by an air suction belt or the like, and is transferred by the fixing unit 70. The toner image is fixed on the transfer material S, and then the transfer material S is discharged onto the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

  Next, the operation of forming a full color image using this full color image forming apparatus will be specifically described.

  First, the photosensitive drum 10 and the intermediate transfer belt 40 are rotationally driven in the respective directions at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 111.

  The photosensitive drum 10 thus charged is exposed to a yellow image by the laser scanning optical system 20 to form an electrostatic latent image of the yellow image on the photosensitive drum 10. A yellow toner charged by a toner regulating member is supplied from a developing cartridge 31Y containing yellow toner in the photosensitive drum 10 to develop a yellow image, and the yellow toner image is thus formed on the photosensitive drum 10 formed with the yellow toner image. On the other hand, the intermediate transfer belt 40 is pressed by the primary transfer roller 41, and the yellow toner image formed on the photosensitive drum 10 is primarily transferred to the intermediate transfer belt 40.

  After the yellow toner image is transferred to the intermediate transfer belt 40 in this way, the full-color developing cartridge 30 is rotated about the support shaft 33, and the developing cartridge 31M containing magenta toner is moved to the photosensitive drum 10. As in the case of the yellow image, the magenta image is exposed to the photosensitive drum 10 charged by the laser scanning optical system 20 to form an electrostatic latent image. Is developed by a developing cartridge 31M containing magenta toner, and the developed magenta toner image is primarily transferred from the photosensitive drum 10 to the intermediate transfer belt 40, and in the same manner, exposure of a cyan image and a black image is performed. Development and primary transfer are sequentially performed, and yellow, magenta, cyan, and black toner images are formed on the intermediate transfer belt 40. Superimposed in sequence to form a full color toner image.

  When the final black toner image is primarily transferred onto the intermediate transfer belt 40, the transfer material S is fed between the secondary transfer roller 43 and the intermediate transfer belt 40 by the timing roller 63, and the secondary transfer roller. 43, the transfer material S is pressed against the intermediate transfer belt 40, and the full-color toner image formed on the intermediate transfer belt 40 is secondarily transferred onto the transfer material S.

  When the full-color toner image is secondarily transferred onto the transfer material S in this way, the transfer material S is guided to the fixing means 70 by the conveying means 66, and the full-color toner transferred by the fixing means 70 is transferred. The image is fixed on the recording material S, and then the transfer material S is discharged onto the upper surface of the apparatus main body 100 through the vertical conveyance path 80.

    FIG. 3 is an explanatory cross-sectional view showing an example of the configuration of a developing cartridge for a one-component developer.

  The developing cartridge 31 has at least a developing roller 25 and a regulating blade 28, and is used as a developing device for non-magnetic one-component toner.

  The developing cartridge 31 has a buffer chamber 26 adjacent to the developing roller 25 and a hopper 27 adjacent to the buffer chamber 26.

  In the buffer chamber 26, a regulating blade 28, which is a toner regulating member, is arranged in a state of being pressed (contacted) with the developing roller 25. The regulating blade 28 regulates the charge amount and adhesion amount (conveyance amount) of the toner on the developing roller 25. Further, it is possible to further provide an auxiliary blade 29 for assisting regulation of the toner charge amount and adhesion amount on the developing roller 25 on the downstream side of the regulating blade 28 with respect to the rotation direction of the developing roller 25.

  A supply roller 30 is pressed against the developing roller 25. The supply roller 30 is driven to rotate in the same direction as the developing roller 25 (counterclockwise direction in the drawing) by a motor (not shown). The supply roller 30 has a conductive cylindrical substrate and a foam layer formed of urethane foam or the like on the outer periphery of the substrate.

  The hopper 27 contains toner T which is a non-magnetic one-component developer. The hopper 27 is provided with a rotating body 35 for stirring the toner T. A film-like conveying blade is attached to the rotator 35, and the toner T is conveyed by the rotation of the rotator 35 in the direction of the arrow. The toner T conveyed by the conveying blades is supplied to the buffer chamber 26 via a passage 32 provided in a partition wall that separates the hopper 27 and the buffer chamber 26. The shape of the conveying blade is bent while conveying the toner T in front of the rotation direction of the blade as the rotating body 31 rotates, and returns to a straight state when reaching the left end of the passage 32. Thus, the blade T supplies the toner T to the passage 32 by making the shape return straight through the curved state.

  The passage 32 is provided with a valve 321 for closing the passage 32. This valve 321 is a film-like member, one end of which is fixed to the upper side of the right side of the passage 32 of the partition wall. When the toner T is supplied from the hopper 27 to the passage 28, the valve 321 is pushed rightward by the pressing force from the toner T. 32 can be opened. As a result, the toner T is supplied into the buffer chamber 26.

  In the developing cartridge 31, the developing roller 25 is rotationally driven in the arrow direction during image formation, and the toner in the buffer chamber 26 is supplied onto the developing roller 25 by the rotation of the supply roller 34. The toner T supplied onto the developing roller 25 is charged and thinned by the regulating blade 28 and the auxiliary blade 29, and then conveyed to a region facing the image carrier, where the electrostatic latent image on the image carrier is transferred. It is used for development. The toner that has not been used for development is neutralized by the neutralization blade 24 as the developing roller 25 rotates. After reducing the electrostatic adhesion force between the developing roller 25 and the toner, the toner is scraped and collected from the developing roller 25 by the supply roller 34.

In the present invention, the contact pressure average of the regulating blade 28 that contacts the developing roller 25 is preferably 10 to 50 N / m, and more preferably 15 to 45 N / m.
By setting the contact pressure within the above range, the non-magnetic one-component toner can be transported in a uniform thickness without damaging the resin layer of the developing roller, and a uniform charge amount is imparted to the non-magnetic one-component toner. be able to.

  The regulating blade 28 used in the present invention is installed in the developing cartridge 31 for the purpose of uniformly thinning the toner on the surface of the developing roller 25 and uniformly charging the toner.

As the regulating blade 28, phosphor bronze having a spring elasticity capable of uniformly thinning and charging the non-magnetic one-component toner and controlling the average contact pressure to the developing roller within a specified range is used.
Phosphor bronze can provide a stable charge to the non-magnetic one-component toner as compared with other metal elastic materials (for example, stainless steel).
This is presumed that since the phosphor bronze charging sequence is more positive than stainless steel, the non-magnetic one-component toner can be charged more stably than stainless steel.
The material of the phosphor bronze plate is preferably a JIS H3731 equivalent.
The thickness of phosphor bronze is not particularly limited, but if a thickness of 0.03 to 0.12 mm is used, the contact pressure average can be easily adjusted to the above range.

  The regulating blade 28 is fixed by a holder, and is used by being attached to the developing cartridge 20 while being fixed to the holder.

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

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the text, “part” means “part by mass”.

[Preparation Example 1 of Shell Resin Fine Particle Dispersion]
Put 430 parts of deionized water in a separable flask equipped with a thermometer, reflux condenser, stirrer and monomer charger, and after replacing oxygen with nitrogen gas, the temperature was raised to 70 ° C. and potassium persulfate (KPS) 5 parts were added and stirred.
A separable flask equipped with the same apparatus as above was prepared, and as vinyl polymerizable monomer C, 44 parts of methyl methacrylate (MMA), 44 parts of n-butyl acrylate (BA), and polymerizable monomer A 100 parts of the above compound (A-1) (2,2,2-trifluoroethyl methacrylate), 12 parts of methacrylic acid (MAA) as a polymerizable monomer B having an acidic polar group, a chain transfer agent Then, 1 part of n-octyl-3-mercaptopropionic acid ester is emulsified with 480 parts of deionized water and 9 parts of an anionic surfactant (sodium dodecylbenzenesulfonate: SDS). It added to the separable flask containing potassium sulfate and polymerized for 20 minutes.
Furthermore, the remaining emulsion was dripped continuously in the flask over 5 hours. Then, the mixture was further reacted at 75 ° C. for 3 hours, cooled to 50 ° C., diluted 5-fold with ion exchange water, adjusted to pH 8 with aqueous ammonia, and a dispersion of shell resin fine particles [S1] was obtained. The average particle diameter of the shell resin fine particles [S1] was 95 nm in terms of volume-based median diameter.

[Preparation Examples 2-5 of Shell Resin Fine Particle Dispersion]
In the same manner as in Preparation Example 1 of Shell Resin Fine Particles, except that the polymerizable monomer A, the polymerizable monomer B, and the vinyl polymerizable monomer C are changed as shown in Table 1, the shell resin fine particles are similarly produced. Dispersions [S2] to [S5] were prepared.

[Preparation Example 6 of Shell Resin Fine Particle Dispersion (Core Shell Structure)]
(1) Formation of core part 998 parts of deionized water was put into a separable flask equipped with a thermometer, a reflux condenser, a stirrer, and a monomer charger, and oxygen was replaced with nitrogen gas, and then the temperature was raised to 72 ° C. Then, 5 parts of potassium persulfate was added and stirred.
A separable flask equipped with the same apparatus as described above was prepared. As the vinyl polymerizable monomer C, 44 parts of methyl methacrylate, 44 parts of n-butyl acrylate, and as the polymerizable monomer A, the compound (A- 1) 100 parts of 2,2,2-trifluoroethyl methacrylate, 12 parts of methacrylic acid as polymerizable monomer B, and 1 part of n-octyl-3-mercaptopropionic acid ester as chain transfer agent 191 5% of the emulsion emulsified with 2 parts of SDS was added to a separable flask containing potassium persulfate as a seed and polymerized for 20 minutes. Furthermore, the remaining emulsion was dripped continuously in the flask over 1.5 to 2 hours to form a core part.
(2) Formation of shell part Then, it was made to react for 1 hour, and like a core part, as vinyl-type polymerizable monomer C, 44 parts of methyl methacrylate, 44 parts of n-butyl acrylate, and polymerizable monomer B, What was emulsified with 12 parts of methacrylic acid and 1 part of n-octyl-3-mercaptopropionic ester as a chain transfer agent was continuously dropped into the above 3 liter separable flask over 1 to 2 hours to form a shell part. .
Then, the mixture was further reacted at 75 ° C. for 2 hours, then cooled to 50 ° C. and adjusted to pH 8 with ammonia water to obtain a dispersion of shell resin fine particles [S6] having a core-shell structure.

[Preparation Example 7 of Shell Resin Fine Particle Dispersion]
In the same manner as in Preparation Example 1 of Shell Resin Fine Particles, except that only polymerizable monomer B and vinyl polymerizable monomer C were used and changed as shown in Table 1, comparative shell resin fine particles [S7 A dispersion was prepared.

  Table 1 shows a list of the structures and physical properties of the obtained shell resin fine particles [S1] to [S7].

[Preparation Example 1 of Binder Fine Particle Dispersion]
(1) First-stage polymerization An anionic surfactant (C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na) was added to a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. A surfactant solution (aqueous medium) in which 0.08 g was dissolved in 3010 g of ion-exchanged water was charged, and the temperature in the flask was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant solution, an initiator solution in which 9.2 g of a polymerization initiator (potassium persulfate) was dissolved in 200 g of ion-exchanged water was added, the temperature was adjusted to 75 ° C., and then 70.1 g of styrene and n-butyl. A monomer mixture composed of 19.9 g of acrylate and 10.9 g of methacrylic acid was dropped over 1 hour, and this system was heated and stirred at 75 ° C. for 2 hours to perform polymerization (first stage polymerization). A latex was prepared. This is referred to as “latex (1H)”.

(2) Second-stage polymerization In a flask equipped with a stirrer, it consists of 105.6 g of styrene, 30.0 g of n-butyl acrylate, 6.2 g of methacrylic acid, and 5.6 g of n-octyl-3-mercaptopropionic acid ester. To the monomer mixture, 98.0 g of “HNP-57” (manufactured by Nippon Seiwa Co., Ltd.) was added as a wax, heated to 90 ° C. and dissolved to prepare a monomer solution.
On the other hand, a surfactant solution in which 1.6 g of an anionic surfactant (C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na) was dissolved in 2700 ml of ion-exchanged water was heated to 98 ° C. After 28 g of latex (1H) in terms of solid content was added to the solution, the monomer solution was added by a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. A dispersion (emulsion) containing emulsified particles (oil droplets) was prepared by mixing and dispersing for a time.
Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion exchange water and 750 ml of ion exchange water are added to this dispersion (emulsion). Polymerization (second stage polymerization) was performed by heating and stirring for 12 hours to obtain a latex. This is referred to as “latex (1HM)”.

(3) Third-stage polymerization An initiator solution in which 7.4 g of a polymerization initiator (KPS) is dissolved in 200 ml of ion-exchanged water is added to latex (1HM), and 300 g of styrene, n -A monomer mixed solution consisting of 95 g of butyl acrylate, 15.3 g of methacrylic acid, and 10.4 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. to obtain a dispersion of binder resin fine particles [1].
The binder resin fine particles had peak molecular weights of 1380000, 80000 and 13000, and the average particle size was 122 nm.

(Preparation of colorant fine particle dispersion)
SDS 59.0 g was dissolved in 1600 ml of ion-exchanged water with stirring. I. Pigment red 122 420.0 g was gradually added, and then dispersion treatment was performed using “CLEARMIX” (manufactured by M Technique Co., Ltd.), whereby a dispersion of colorant fine particles (hereinafter referred to as “colorant fine particle dispersion”). [1] ") was prepared. When the particle diameter of the colorant fine particles in this colorant fine particle dispersion [1] was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the volume-based median diameter was 89 nm. there were.

<Toner Preparation Example 1>
Binder resin fine particle [1] dispersion 420.7 g (solid content conversion), ion-exchanged water 900 g, colorant fine particle dispersion [1] 166 g, temperature sensor, cooling pipe, nitrogen introducing device, stirring device Was stirred in a reaction vessel (four-necked flask). After adjusting the temperature in the container to 30 ° C., a 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8 to 10.0.
Next, an aqueous solution in which 12.1 g of magnesium chloride hexahydrate was dissolved in 1000 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 6 to 60 minutes to produce associated particles. In this state, the particle size of the associated particles was measured with “Coulter Counter TA-II”, and when the volume-based median diameter became 5 μm, an aqueous solution in which 40.2 g of sodium chloride was dissolved in 1000 ml of ion-exchanged water was obtained. The particle growth was once stopped by addition to obtain core particles [1]. Next, 30 g of the dispersion of shell resin fine particles [S1] is added in terms of solid content, and further heated and stirred at a liquid temperature of 98 ° C. for 2 hours as an aging treatment, and 40.2 g of sodium chloride is dissolved in 1000 ml of ion-exchanged water. The aging of the particles was temporarily stopped by adding the prepared aqueous solution, and the particles were continuously fused by heating and stirring at a liquid temperature of 98 ° C. for 1 to 4 hours. Then, it cooled to 30 degreeC, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced association particles were filtered, washed repeatedly with ion exchange water at 45 ° C., and then dried with hot air at 40 ° C. to obtain toner particles [1]. The volume-based median diameter of the toner particles [1] was 6.4 μm.
0.8% by mass of silica fine particles [SI-1] shown in Table 2 below and 0.03% by mass of composite inorganic fine particles [FM-1] shown in Table 3 below are added to the dried toner particles [1]. The toner [1] was produced by mixing with a Henschel mixer and passing through a sieve having an opening of 50 μm to remove coarse particles and aggregates.

<Toner Preparation Examples 2 to 15>
Toners [2] to [15] were prepared in the same manner as in Toner Preparation Example 1, except that the type of shell resin fine particles and the type and amount of external additive were changed according to Tables 2 to 5.

Using the toners [1] to [15] described above as a non-magnetic one-component developer, halftone uniformity, fog and sleeve ghost were evaluated.
As an evaluation machine, a commercially available digital color printer “magiccolor 5440DL” (manufactured by Konica Minolta Business Technologies) was used. The above toner was added, 200,000 sheets were printed in an environment of 20 ° C./50% RH, and the following evaluation was performed in an initial state and a state after enduring 200,000 sheets. The results are shown in Table 6.

[Halftone uniformity]
The uniformity (non-uniformity) of the halftone image due to the change in toner transportability after the endurance of 200,000 sheets was evaluated. Visual evaluation was performed in four stages as follows.
A: Uniform image without unevenness B: Extremely thin stripe-like unevenness exists C: Several thin stripe-like unevennesses exist, but there is no practical problem Level D: Existence of several uneven stripe-like unevennesses is evaluated As for the rank, AC was passed and D was rejected.

[Fog]
The fog density at the initial stage and after endurance of 200,000 sheets was measured using a reflection densitometer “RD-918” (manufactured by Macbeth). The fog density is a value calculated as follows. The density of printing paper (white paper) that has not been printed is measured at 20 locations, and the average value is defined as the white paper density. Next, the density of the white background portion of the printing paper on which the plain image is printed is similarly measured, and The value obtained by subtracting the white paper density from the average value was defined as the fog density. If the fog density is less than 0.005, it is good, and if it is less than 0.010, it is judged acceptable without any practical problem.

[Sleeve Ghost]
The position of the developing sleeve that developed the image where the solid white portion and the solid black portion are adjacent to each other exists at the developing position at the next rotation of the developing sleeve, and is set so as to develop the halftone. It checked visually and evaluated by the following evaluation criteria.
◎: Difference in density is not observed ○: Difference in density is observed, but practical level ×: Difference in density is observed, impractical level

  From the above results, in the toners of the present invention according to Examples 1 to 10, good results were obtained in any of halftone uniformity, fog and sleeve ghost.

DESCRIPTION OF SYMBOLS 1 Load unit 2 Sample 3 Sample height 4 Main body cell 5 High voltage power supply 6 Resistance measuring device 10 Photosensitive drum 111 Charging brush 112 Cleaner 20 Laser scanning optical system 24 Static elimination blade 25 Developing roller 26 Buffer chamber 27 Hopper 28 Regulation blade 29 Auxiliary Blade 30 Full-color developing cartridge 31 Developing cartridge 32 Passage 321 Valve 33 Support shaft 34 Supply roller 35 Rotating body 40 Intermediate transfer belt 41 Primary transfer roller 42 Support roller 43 Secondary transfer roller 50 Cleaner 60 Paper feed means 61 Paper feed tray 62 Feed Paper roller 63 Timing roller 66 Conveying means 70 Fixing means 80 Vertical conveying path 100 Apparatus main body S Transfer material

Claims (6)

In the toner for developing an electrostatic image used as a non-magnetic one-component developer,
A shell layer containing a copolymer resin formed by a polymerizable monomer having fluorine and a polymerizable monomer having an acidic polar group is formed on the core particle containing the binder resin. Consists of toner particles and external additives,
The toner for developing an electrostatic charge image, wherein the external additive contains at least silica fine particles and composite inorganic fine particles made of an inorganic compound containing magnesium and aluminum. The composite inorganic fine particles have a magnesium / aluminum content ratio [Mg (atm%) / Al (atm%)] of 1 to 4, static resistance of 1 × 10 ¹⁰ to 1 × 10 ¹³ Ω · cm, number average primary. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the toner has a particle diameter of 50 to 1000 nm. It said external additive toner according to claim 1 or claim 2, characterized in that the titanium-containing oxide fine particles are further contained.   The composite inorganic fine particles are contained in a proportion of 0.02 to 1.0 mass% with respect to the total mass of the electrostatic charge image developing toner. The toner for developing an electrostatic image according to the description.   The electrostatic charge image developing toner according to claim 1, wherein the binder resin according to the core particle is made of a styrene-acrylic copolymer resin. An image forming method using the toner for developing an electrostatic image according to claim 1.