JP2003215838A - Electrostatic charge image developing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having high electrification ability required for development, having little fogging and causing little changes in the picture quality during continuous printing even when the toner is adopted for a development method requiring durability. <P>SOLUTION: The electrostatic charge image developing toner comprises mother particles containing at least a binder resin and a coloring agent with addition of external additive fine particles. The external additive fine particles are fixed to the surfaces of the mother fine particles. The ratio of the specific surface area of the toner after fixing by the BET method to the specific surface area of the mother particles before fixing by the BET method is ≤3.2. The absolute charge amount in at least one kind of the external additive fine particles is ≥300 μC/g. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner. More specifically, the present invention relates to a toner for developing an electrostatic charge image, which can be preferably used in a printer or the like using an electrophotographic method, particularly a non-magnetic one-component developing system. The toner of the present invention has a high charging ability necessary for developing property, has less fog, and is applied to a developing method requiring durability,
Has little change in image quality during continuous shooting, and has excellent fixing and blocking resistance.

[0002]

2. Description of the Related Art As a dry developing method used in electrophotography, there are generally used a two-component developing method in which a carrier such as iron powder or ferrite powder is mixed with a toner and a one-component developing method in which no carrier is used. is there. Of these, the former requires a so-called toner concentration control mechanism that replenishes only the necessary amount with the consumption of toner, and therefore has a problem in terms of size increase and cost increase of the apparatus. On the other hand, in the latter, the magnetic one-component system and the non-magnetic one-component system are mainstream, and the size of the device can be reduced. Therefore, this system is mainly used in personal printers and full-color printers, which have been increasing in recent years. Is coming. The performance required of toner is that when an image is formed, the image density is sufficient and there are no image defects, it can be used stably for a long period of time, it is well fixed on paper, and it blocks during the toner production process, storage, and transportation. There is a wide variety of problems such as the production process, the formed image, and problems with the equipment used. Among these requirements, there are some requirements which show contradictory tendencies such as fixing property and blocking resistance property, and are not easily compatible with each other.

In order to meet such requirements, many proposals have been made regarding the properties of the materials to be melt-kneaded, the compounding recipe, the kneading conditions and the like. Also, many proposals have been made for external additives to be attached to the toner surface.
A method using silica coated with amino-modified silicone (JP-A-59-187539), a method using silica treated with a specific silane coupling agent (JP-A-50-198470), and the like have been proposed. There is.

[0004]

However, these conventional methods do not always satisfy the performance required for the toner. Further, depending on the development, transfer, and other methods adopted in the apparatus, sufficient effects cannot always be obtained. In particular, in the one-component method in which a relatively large load is applied to the toner in order to ensure the charging property, continuous continuous copying tends to cause, for example, detachment of the externally added silica or the like, embedding in the toner, and the like. It may be difficult to maintain the chargeability required for proper development. The present invention has been made in view of the above circumstances, and its problem is that stable image quality can be obtained even in continuous actual copying by a developing method such as a one-component method that places a heavy load on toner, and fixability and blocking resistance. It is to provide a toner having excellent compatibility.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above problems, and as a result, by continuously fixing the highly charged externally added fine particles to the surface of the toner base fine particles by a specific method, It was found that the change in the physical properties of the toner becomes small, and the fixing property and the blocking resistance are both effective, and the present invention has been completed based on such knowledge. That is, the gist of the present invention is a toner for developing an electrostatic charge image, which is obtained by adding externally added fine particles to base fine particles containing at least a binder resin and a colorant, wherein the externally added fine particles are fixed on the surface of the base fine particles. And the ratio of the BET specific surface area of the toner after fixation to the specific surface area of the base fine particles before fixation by BET method is 3.2 or less, and the charge amount of at least one of the externally added fine particles is An electrostatic charge image developing toner having an absolute value of 300 μC / g or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The base fine particles used in the present invention are produced from a binder resin, a colorant and other additives according to a conventional method. As the binder resin, various known resins suitable for toner can be used. For example, styrene resin, vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, saturated polyester resin, unsaturated polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, There are ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin and the like, and more preferable resins include styrene resin, saturated or unsaturated polyester resin, epoxy resin and the like. These resins may be used alone or in combination. Further, these resins may be used as a non-crosslinked resin, a crosslinked resin, or a mixture thereof depending on the fixing method. Further, as the method for producing the binder resin, there are bulk polymerization, suspension polymerization, solution polymerization, emulsion polymerization, interfacial polymerization, gas phase polymerization and the like, but the method can be used regardless of the polymerization method. The softening point of the binder resin is preferably 90 to 150 ° C, more preferably 100 to 140 ° C, and the glass transition point is preferably 45 to 70 ° C, more preferably 50 to 67 ° C. When the softening point and the glass transition point are within the above ranges, the adhering property of the externally added fine particles becomes good, which is desirable.

Examples of the styrene resin include polystyrene, polychlorostyrene, poly-α-methylstyrene,
Styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid Ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc. ), Styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-
Ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.),
Examples thereof include styrene-α-chloroacrylic acid methyl copolymer, styrene-acrylonitrile-acrylic acid ester copolymer and the like. These styrenic resins can be used as a crosslinked resin by copolymerizing a crosslinkable monomer, if necessary. Examples of the method for producing these styrene resins include bulk polymerization, suspension polymerization, solution polymerization and emulsion polymerization.

The above polyester resin includes a divalent alcohol monomer, a divalent carboxylic acid monomer and / or a derivative thereof, and, if necessary, a trivalent or higher polyvalent alcohol monomer and a polyvalent carboxylic acid monomer. Obtained by polycondensation with a monomer and / or its derivative. Examples of the dihydric alcohol monomer include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3
-Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol and other diols, bisphenol A, polyoxyethylenated bisphenol A, polyoxypropyleneized bisphenol A and other etherified bisphenols, and others The divalent alcohol monomer of is mentioned. Examples of the divalent carboxylic acid monomer and / or its derivative include isophthalic acid, terephthalic acid, adipic acid, sebacic acid, diphenic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, anhydrides or lower alkyl esters of these acids. The main component may be mentioned. Examples of the trihydric or higher polyhydric alcohol monomer include trimethylolethane, trimethylolpropane, glycerin and pentaerythritol. Trivalent or higher polycarboxylic acids and / or derivatives thereof include trimellitic acid, cyclohexanetricarboxylic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, octanetetracarboxylic acid, and anhydrides or lower alkyls of these acids. Esters and the like can be mentioned. In addition, examples of methods for producing these polyester resins include bulk polymerization, solution polymerization, and interfacial polymerization.

Known pigments, dyes and the like can be used as the colorant. For example, titanium oxide, zinc white,
Carbon black, alumina white, calcium carbonate, navy blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, anthraquinone dye, monoazo and disazo dyes. A colorant such as a pigment is used alone or in combination as a color of the corresponding toner. The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and is, for example, 3 to 20 parts by weight with respect to 100 parts by weight of the binder resin. preferable.

Further, the toner of the present invention may be a magnetic toner using known magnetic particles as a colorant. As the magnetic particles, the operating environment temperature of a copying machine (usually 0
Ferromagnetic materials, ferromagnetism, or the like at around (C to 60C) are used. Examples of the magnetic particles used include magnetite (Fe ₃ O ₄ ), maghematite (γ-Fe ₂ O ₃ ), an intermediate between magnetite and maghematite, and ferrite (M _X Fe _{3 -X} O ₄ ;
M is Mn, Fe, Co, Ni, Cu, Mg, Zn, Cd
Etc. or their mixed crystal system) etc. spinel ferrite or BaO
· 6Fe ₂ O _3, 6-cubic ferrite such as _{SrO · 6Fe 2 O 3, Y} 3 Fe 5 O 12, Sm 3 Fe 5 O garnet-type oxides such as _12, rutile-type oxide such as CrO _2, Fe, Mn, N
Among metals such as i, Co and Cr, and other ferromagnetic alloys, those exhibiting ferromagnetism and ferrimagnetism at around 0 ° C to 60 ° C are mentioned, and among them, magnetite, maghematite, intermediate between magnetite and maghematite. Fine particles having an average particle size of 3 μm or less, more preferably about 0.05 to 1 μm, are preferable in terms of performance and cost. The magnetic fine particles are not limited to being used alone, but two or more kinds may be used in combination. When added from the viewpoint of scattering prevention, charge control, etc. while maintaining the properties as a non-magnetic toner, the addition amount is 0.5 to 10 parts by weight, preferably 0.5 parts by weight with respect to 100 parts by weight of the binder resin. ~ 8 parts by weight, more preferably 1
~ 5 parts by weight. When used as a magnetic toner, the addition amount is preferably 20 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the binder resin.

If desired, other additives may be added. For example, when it is desired to impart chargeability to the toner, known positively or negatively chargeable charge control agents may be used alone or in combination. Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds, imidazole compounds, polyamine resins and the like. Examples of the negatively chargeable charge control agent include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, calixarene compounds, and alkylsalicylic acid metal compounds. Also in the selection of the charge control agent, it is preferable to use the one which does not contain volatile impurities as much as possible, like the colorant.

The amount of the charge control agent used may be selected according to the desired amount of charge. The addition amount of the charge control agent is usually about 0.05 to 10 parts by weight with respect to 100 parts by weight of the binder resin, and preferably 1 to 5 parts by weight with respect to 100 parts by weight of the binder resin. If the content of the charge control agent is too low, the effect of improving the chargeability cannot be expected, and if it is excessive, the quality of the toner deteriorates. In addition, polypropylene wax, polyethylene wax, paraffin wax, higher fatty acid, fatty acid amide, metal soap, etc. may be added in an amount of about 0.1 to 30 parts by weight with respect to 100 parts by weight of the binder resin for the purpose of improving offset resistance. Good.

The base fine particles of the toner can be produced from the above-mentioned components by a conventional method. Normally,
First, a binder resin, a colorant, and a charge control agent and other additives which are optionally added are uniformly dispersed and mixed in a mixer, and then the mixture is sealed in a kneader or a uniaxial or biaxial extruder. Melt-kneading, cooling, coarse crushing with a crusher, hammer mill, etc., fine crushing with a jet mill, high-speed rotor rotary mill, etc., wind classifier (for example,
Inertia classification method elbow jet, centrifugal force classification method microplex, DS separator, etc.) are used for classification.

The particle diameter of the base fine particles of the obtained toner is preferably 4 to 15 μm, more preferably 5 to 9 μm. Here, the particle size is Multisizer (made by Coulter)
Etc. can be used for measurement. The charge amount of the base fine particles is preferably 40 μC / g or less in absolute value, more preferably 35 μC / g or less in absolute value. If the charge amount of the base fine particles exceeds the above range, the externally added fine particles may be poorly dispersed due to the repulsion between the externally added fine particles and the base fine particles during external addition, which may adversely affect the image quality, which is not preferable. The charge amount of the base fine particles can be measured by the following method. [Measurement Method of Charge Amount] 50 g of non-coated ferrite carrier (F100 manufactured by Powdertech Co., Ltd.) and 0.1 g of externally added fine particles are weighed and stirred for 1 minute with a reciprocal shaker (stirring strength 500r.
pm). The amount of charge is measured with a blow-off measuring device (manufactured by Toshiba Chemical Co.).

In the present invention, the externally added fine particles are fixed to the surface of the above-mentioned base fine particles in order to give the toner good chargeability. The externally added fine particles to be fixed are various inorganic and organic fine powders, and for example, fine powders of silica, alumina, titania, magnetite, ferrite, cerium oxide, strontium titanate and the like can be used, and these are silicon oil and silicon varnish. The surface may be treated with a silane coupling agent or the like. In order for the toner to have good chargeability, it is necessary that the externally added fine particles contain particles having an absolute value of the charge amount of 300 μC / g or more and 1500 μC / g or less. The absolute value of the charge amount of the externally added fine particles is preferably 400 μC / g or more, more preferably 450 μC / g or more. When the absolute value of the charge amount of the externally added fine particles is 300 μC / g or less, sufficient chargeability cannot be imparted to the toner, and adverse effects such as deterioration of fogging occur, which is not preferable. The charge amount of the externally added fine particles can be measured by the same method as the measurement of the charge amount of the base fine particles. Further, it is preferable that the charge of the base fine particles and the charge of the externally added fine particles have the same polarity from the viewpoint of stabilizing the charge amount.

Further, it is preferable that the externally added fine particles include particles having a specific surface area of 120 m ² / g or more as measured by the BET method. As a result, sufficient fluidity is imparted to the toner, and the followability of the solid solid portion is positively affected. The BET value is a value obtained by measuring the N ₂ adsorption specific surface area using a Flowsorb 2300 manufactured by Shimadzu Corporation. Further, the amount of the externally added fine particles is preferably an amount such that the coverage of all the externally added fine particles with respect to the base fine particles is 80% or more, more preferably 90% or more, which is determined by the following formula (1). The amount is preferably 95% or more. When the coverage is 80% or more, the toner can be provided with sufficient chargeability and fluidity, which has a favorable effect on a decrease in image density, deterioration of white background fog, and followability of solid solid portions.

[0017]

[Equation 2]

[0018]

[Table 2] In the formula (1), Dt: Average particle size of base fine particles (μm) ρt: True density of base particles (g / cm3) Dn: average particle diameter (μm) of externally added fine particles n ρn: True density of externally added fine particles n (g / cm3) Wn: Number of externally added fine particles n added (Parts by weight when the base fine particles are 100 parts by weight) a: Number of types of external additives.

Here, the average particle diameter (Dt) of the base fine particles
Can be determined by, for example, Multisizer (manufactured by Coulter Co.). Further, the average particle diameter (Dn) of the externally added fine particles can be obtained, for example, from an image obtained by observation with a transmission electron microscope by using an image processing device that automatically calculates as necessary. The true density (ρt) of the base fine particles and the true density (ρn) of the externally added fine particles can be determined by appropriately selecting from a general density measuring method such as a differential pressure method, a float-sink method, and an immersion method.

Since the specific surface area of the externally added fine particles to be fixed by the BET method is much larger than the specific surface area of the base fine particles, the specific surface area of the toner after fixation by the BET method is usually the same as the specific surface area of the base fine particles before fixation. Increase in comparison. In the present invention, the ratio of the specific surface area of the toner after fixation to the specific surface area of the base fine particles before fixation by the BET method is 1 or more and 3.2 or less, preferably 3.0 or less, and more preferably 2.8 or less. is there. If the ratio of the specific surface area of the toner after fixation to the specific surface area of the base fine particles before fixation exceeds the above-mentioned value, the change in the externally added fine particle adhesion state in continuous actual copying becomes large and the deterioration of image quality becomes remarkable, which is not preferable. .

The method of fixing the externally added fine particles to the surface of the mother fine particles in the present invention is not limited, but as described above, the ratio of the specific surface area of the toner after fixing to the specific surface area of the mother fine particles before fixing is within 3.2. In order to reduce the temperature, it is preferable to carry out under compressive shear stress conditions. That is, using a device (hereinafter, referred to as a compression shearing treatment device) capable of applying a compressive stress and a shearing stress to the particle surface without substantially crushing the treated particles, Place the mixture with externally added particles under compressive shear stress conditions,
It is desirable to fix the externally added fine particles to the surface of the base fine particles. By this fixing treatment, the externally-added fine particles are firmly fixed to the surface of the base fine-particles, and the detachment and embedding of the externally-added fine particles are less likely to occur even during continuous actual shooting. Is unlikely to occur.

The compression shearing treatment apparatus preferably used is generally a narrow one composed of a head surface and a head surface, a head surface and a wall surface, or a wall surface and a wall surface which move relatively while maintaining the surface distance between them. Since the particles to be treated have a gap portion and are forced to pass through the gap portion, compressive stress and shear stress are applied to the particle surface without being substantially crushed. There is. Examples of the compression shearing treatment device used include a mechanofusion device manufactured by Hosokawa Micron and a treatment device having a similar mechanism. The fixing treatment condition by the compression shearing treatment device is not limited because it is optimized depending on the shape of the device used, the softening point of the base fine particles, the glass transition temperature, etc., but is usually 40 to 80 ° C., preferably 50 to 70 ° C.
It is desirable to process in. The treatment time is not limited because it is optimized according to the type of equipment, the scale of the equipment, the treatment amount, the composition of the base fine particles and the externally added fine particles, etc.
It is about 0 to 120 minutes.

The toner of the present invention is not limited in the developing method used as long as it develops an electrostatic image, and may be used as either a magnetic toner or a non-magnetic toner. It may be used for any system development. Further, a contact charging method or a non-contact charging method may be used, and a contact developing method or a non-contact developing (flying developing) method may be used. Further, it can be used for any of black toner, single color toner and full color toner. Among them, the toner of the present invention is suitable as a toner for non-magnetic one-component development, and can be suitably used as a color toner or a full-color toner.

[0024]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded. In addition, "part" represents "part by weight" unless otherwise specified.

[Example 1]

[0026]

[Table 3]   Polyester resin FC1198     (Softening point 135 ° C, glass transition point 62 ° C, manufactured by Mitsubishi Rayon Co., Ltd.) 100 parts   Colorant Pigment Red No. 122                           (Manufactured by Dainippon Ink and Chemicals, Inc.) 8 parts   Charge control agent LR147 (manufactured by Nippon Carlit) 1 part

After the above materials were mixed by a mixer, they were melt-kneaded by a twin-screw kneader (PCM-30 manufactured by Ikegai Iron Works Co., Ltd.) and pulverized by a jet mill to obtain base fine particles having an average particle size of 8.5 μm. . The charge amount of the base fine particles was 27 μC / g, and the specific surface area by the BET method was 0.45 m ² / g. A charge amount of 750 μC /
1.25 parts of silica (R974, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 170 m ² / g and a charge amount of 460 μC /
g, 1.0 part of silica (manufactured by Nippon Aerosil Co., Ltd .: NY50) having a specific surface area of 30 m ² / g, and treated with a compression shearing device (manufactured by Hosokawa Micron Co .: Mechanofusion System AMS-LAB) at 60 ° C. for 15 minutes. Then, silica was fixed on the base fine particles to obtain a toner. The average particle diameter of the toner is 8.5 μm, and the specific surface area by the BET method is 1.1 m.
The coating rate of ² / g and the externally added fine particles was 102.5%.

[Example 2] A toner was obtained in the same manner as in Example 1 except that the amount of externally added fine particles in Example 1 was changed to 1.6 parts of R974. The average particle size of the toner is 8.5μ
m, the specific surface area by the BET method was 1.0 m ² / g, and the coverage of the externally added fine particles was 93.7%. [Example 3] The coloring agent in Example 1 was replaced with Pigmen.
t Blue No. A toner was obtained in the same manner as in Example 1 except that 15: 3 (manufactured by Dainippon Ink and Chemicals, Inc.) was used as 7 parts. The charge amount of the base fine particles before the compression shearing treatment was 30 μC / g, and the specific surface area by the BET method was 0.40 m ^2.
/ G, and the average particle size of the toner after compression shearing is 8.
The specific surface area according to the BET method was 5 m, the specific surface area was 1.1 m ² / g, and the coverage of the externally added fine particles was 102.5%.

[Comparative Example 1] A toner was obtained in the same manner as in Example 1 except that the treatment in Example 1 was performed using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). The average particle diameter of the treated toner was 8.5 μm, the specific surface area by the BET method was 1.9 m ² / g, and the coverage of the externally added fine particles was 102.5%. [Comparative Example 2] The externally added fine particles in Example 1 were charged with a charge amount of 2
A toner was obtained in the same manner as in Example 1 except that only 3.0 parts of silica having a specific surface area of 30 m ² / g (50 μC / g, manufactured by Nippon Aerosil Co., Ltd .: RY50) was used. The average particle diameter of the toner after the compression shearing treatment was 8.4 μm, the specific surface area by the BET method was 1.0 m ² / g, and the coverage of the externally added fine particles was 87.9%.

An organic photoconductor (OPC) was used for each of the above toners.
It was mounted on a non-magnetic one-component contact type full-color printer having a photoconductor to perform actual copying, and image evaluation was performed according to the following method. Evaluation is at the beginning of printing (fifth sheet) and 4 kp
(4000th sheet) was judged.

(1) Image Density (Indicated as "ID" in the table) A black solid portion printed with an image pattern having a solid solid portion is an X-lite 936 (light source C) manufactured by Nippon Flat Plate Equipment Co., Ltd.
2, A response). The evaluation criteria are as follows.

[0032]

[Table 4] ○: 1.3 or more, Δ: 0.8 to 1.3, X: 0.8 or less.

(2) Fogging (indicated as "BG" in the table) The white portion of the printed image of (1) above was measured with a whiteness meter manufactured by Nippon Denshoku Co., Ltd. I checked the difference. The evaluation criteria are as follows.

[0034]

[Table 5] ○: 1.0 or less, Δ: 1.0 to 2.0, X: 2.0 or more.

(3) Solid followability (indicated as "solid" in the table) A4 size solid image was printed and evaluated by eye examination. The evaluation criteria are as follows.

[0036]

[Table 6] ◯: No change in image density after the second week of the sleeve, Δ: low image density after the second lap of the sleeve, x: faint after the second lap of the sleeve.

Table 1 shows the production conditions and the like of each example, and Table 2 shows the evaluation results.

[0038]

[Table 7]

[0039]

[Table 8]

As a result of the initial image evaluation and continuous actual shooting, all the toners of Examples 1 to 3 showed good image density, fog and solid followability, but whether the toner of Comparative Example has a problem in the initial image quality, Alternatively, the image quality deteriorated in continuous shooting.

[0041]

According to the present invention, there is provided a toner having a high charging ability necessary for developing property, less fog, and less change in image quality in continuous actual copying even when applied to a developing system requiring durability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shingo Ishiyama             1 Fukuda-cho, Joetsu City, Niigata Prefecture Mitsubishi Chemical Shares             In the company (72) Inventor Masakazu Sugihara             1 Fukuda-cho, Joetsu City, Niigata Prefecture Mitsubishi Chemical Shares             In the company F term (reference) 2H005 AA08 AB03 CB13 EA01 EA10

Claims (5)

[Claims] 1. A toner for developing an electrostatic charge image, comprising external fine particles added to basic fine particles containing at least a binder resin and a colorant, wherein the external fine particles are fixed on the surface of the basic fine particles. And the BE of the toner after fixation with respect to the specific surface area of the base fine particles before fixation by the BET method
The specific surface area ratio by the T method is 3.2 or less, and the absolute value of the charge amount of at least one of the externally added fine particles is 3 or less.
A toner for developing an electrostatic image, characterized by having a content of at least 00 μC / g. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the externally added fine particles are fixed on the surface of the base fine particles under the condition of compressive shear stress. 3. At least one kind of externally added fine particles is
The specific surface area by BET method is 120 m ² / g or more,
The toner for developing an electrostatic charge image according to claim 1 or 2. 4. The toner for developing an electrostatic charge image according to claim 1, wherein the coverage of all externally added fine particles on the base fine particles is 80% or more, which is calculated by the following formula (1). [Equation 1] [Table 1] In the formula (1), Dt: average particle size of base fine particles (μm) ρt: true density of base fine particles (g / cm ³ ) Dn: average particle size (μm) of externally added fine particles n ρn: outside True density of added fine particles n (g / cm ³ ) Wn: Number of parts of externally added fine particles n (parts by weight when base fine particles are 100 parts by weight) a: Number of types of external additives 5. The absolute value of the charge amount of the base fine particles is 40 μC.
The toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the toner is less than / g.