JP3158982B2 - Electrostatic image developing toner and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image used for developing an electrostatic latent image formed by an electrophotographic method or an electrostatic recording method, and a method for producing the same.

[0002]

2. Description of the Related Art At present, a method of visualizing image information through an electrostatic image such as electrophotography is used in various fields. In electrophotography, an electrostatic image is formed on a photoreceptor by a charging step and an exposure step, an electrostatic latent image is developed with a developer containing a toner, and is visualized through a transfer step and a fixing step. The developer used here includes a two-component developer including a toner and a carrier, and a one-component developer using a magnetic toner or a non-magnetic toner alone. As a method for producing the toner, usually, a thermoreversible resin is melt-kneaded with a pigment, a charge controlling agent and a release agent such as wax, and the obtained melt-kneaded product is cooled, finely pulverized, and further classified. A grinding method has been used. Inorganic fine particles and organic fine particles are added to the surface of these toner particles as needed in order to improve fluidity and cleaning properties.

In general, when a toner is kneaded and pulverized, the shape and surface structure of the obtained toner are indefinite, and may vary subtly depending on the pulverizability of raw materials to be used and the conditions of the pulverization process. It is difficult. In particular,
It is known that when a material having high pulverizability is used as a raw material, the toner frequently generates fine powder or deforms the toner due to mechanical force or the like in a developing machine. In such a case, in the case of the two-component developer, there is a problem that the fine powder adheres to the carrier surface and the deterioration of the charge of the developer is accelerated. There is a problem that image quality is likely to be deteriorated due to scattering of toner or deterioration in developability due to change in toner shape. Also, if the molecular weight of the binder resin used to increase the impact resistance is improved, or if a crosslinking agent or the like is used, the kneaded material cannot be sufficiently pulverized to have a particle size of the toner, and high image quality can be obtained. From the viewpoint of reducing the particle size and energy saving.

In recent years, a cleaner-less developing machine has been studied in which transfer residual toner on a photoreceptor is returned to a developing machine and reused. However, this method needs to transfer a large amount of toner used for development. . Since amorphous toner has a larger contact area with the photoreceptor than spherical toner, it is difficult to achieve high transferability with a generally used amount of external additives. Has been attempted to increase the area occupancy of the toner to 100% or more, but transferability is initially improved, but when a mechanical impact force is applied during long-term running or the like. Deterioration in performance due to embedding of the external additive, generation of contamination of the sleeve and carrier due to scattering of the external additive may cause poor charging and poor layer formation, and may scatter on the photoreceptor to become a core of toner adhesion. Further, in the case of a toner to which a release agent such as wax is internally added, exposure of the release agent to the toner surface is often caused by combination with a thermoplastic resin. In particular, when the toner is formed by combining a resin which is imparted with elasticity by a high molecular weight component and is hardly pulverized and a brittle wax such as polyethylene, polyethylene is often exposed on the toner surface. . When such a phenomenon occurs, it is advantageous to release the toner at the time of fixing and to clean the untransferred toner from the photoreceptor.However, since the polyethylene of the surface layer is easily transferred by the mechanical force, the developing roll, Contamination of the photoreceptor and the carrier is likely to occur, causing a reduction in the reliability of image formation. The amorphous toner has insufficient fluidity even when a fluidity aid is added, and during use, the fine particles on the surface move to the concave portions of the toner due to mechanical force, and the fluidity decreases over time.
Developability, transferability and cleaning properties are deteriorated, and if the toner collected by cleaning is returned to the developing machine and reused, the image quality is liable to further deteriorate. To prevent these, if the amount of the flow aid added to the toner is increased,
There are problems that black spots are generated on the photoreceptor and scattering of auxiliary particles occurs. Other known methods include hot air treatment of an irregular toner obtained by kneading and pulverization, and a method of smoothing the surface shape by mechanical impact force. The irregular toner is obtained by a wet method (polymerization method). Since the surface state is less uniform than the toner, the performance deteriorates when a mechanical impact force is applied during long-term running or the like.

[0005] At present, there is a demand for higher quality of copied images by electrophotography and the like, and therefore, toners have been reduced in particle size. Since the conventional kneading and pulverizing method has a large impact in terms of cost in reducing the particle size of the toner, as a resin material to be achieved by the kneading and pulverizing method, a polyester or styrene-acrylic low molecular weight resin having good pulverizability is used. It is being used. However, when these resins are used, although the pulverizability is improved, the resulting toner has the above-described generation of fine powder and deformation of the toner due to mechanical force in a developing machine and the like. . As a method for stably and efficiently producing a toner having a small particle diameter, a polymerization method such as a suspension polymerization method and a dispersion polymerization method is known. The toners obtained by these polymerization methods are spherical with a small particle size, but it is difficult to control the shape. In addition, the spherical toner reduces the contact area with the photoreceptor during use, thereby reducing the adhesive force and improving transferability, but impairs the blade cleaning suitability of the residual toner.

[0006] To improve the above problem, for example, Japanese Patent Publication No. Hei 6-29979 discloses a method in which the ratio between a surfactant and a dispersant used in a reaction such as suspension polymerization is adjusted to a specific value to obtain a spherical shape. It has been proposed to obtain a so-called potato-shaped toner which is far away from the toner. However, in the image formation using this toner, the adhesion between the toner and the photoconductor is increased even though the blade cleaning property is good. Thus, the transferability is low from the beginning. As a method for initially improving the cleaning property, a method of externally adding or precipitating, for example, inorganic fine particles or organic resin fine particles on the toner surface (Japanese Patent Application Laid-Open Nos. Sho 62-266558 and Sho 63-195659) Gazette, JP-A-1-25785
No. 6, Japanese Patent Application Laid-Open No. 1-302270, etc.) have been proposed, but it is inevitable that the external addition structure changes due to long-term running, and it is difficult to maintain blade cleaning properties.

Further, when the toner is produced by the above-mentioned polymerization method, in the polymerization process, for example, a method of adding and then removing an inorganic dispersant, a method of high-speed stirring at the end of the polymerization, and a method of forming an outer shell around core particles. Attempts have been made to impart irregularities to the surface shape of the toner itself by a method of forming, but this method eventually causes the same problems as irregular-shaped toners manufactured by a kneading and pulverizing method, and Since the contact area between the developed toner and the photoconductor becomes larger than that of the spherical toner, there is a problem that transferability is low from the beginning. In addition, in this polymerization method, by using a surfactant and a dispersant in a specific range, a toner having an amorphous shape separated from a spherical shape can be obtained, but in this case, even if the blade cleaning suitability is sufficient. The transferability was poor. As described above, a toner having excellent mechanical impact, high transferability, and blade cleaning suitability has not yet been found.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the kneading and pulverizing method of the toner in the prior art and the above-mentioned problems in the polymerization method of the spherical toner. . That is, the object of the present invention is to control carrier shape and surface composition structure of toner to reduce carrier contamination and photoreceptor contamination, and have good developing property, transfer property and cleaning property, and stable charging property. An object of the present invention is to provide a long-life toner for developing an electrostatic image used in a two-component developer system. Another object of the present invention is to control the shape and surface composition of the toner to prevent development roller contamination and photoreceptor contamination, and to provide good developability, transferability and cleaning properties, and stable image maintenance. An object of the present invention is to provide a toner for developing an electrostatic image used in a one-component developer, which has a property. Another object of the present invention is to stably form a high-quality image even when the toner collected by cleaning is returned to the developing machine and reused in the two-component developer system and the one-component developer system. It is an object of the present invention to provide a toner for developing an electrostatic image that can be used.

[0009]

According to the present invention, there is provided a method for producing a toner for developing an electrostatic image, comprising: a step of melt-kneading a toner raw material containing a binder resin and a colorant; a step of pulverizing the melt-kneaded product; The obtained toner particles in a solvent with a surfactant and
Heating the toner particles in the presence of a dispersion stabilizer to form toner particles having a toner surface roughness index in the range of 1.1 to 1.5, adding inorganic fine powder to the toner particles, mixing the toner particles, The method is characterized in that the method comprises a step of forming toner particles having an inorganic fine powder coverage of 30 to 50% by XPS (X-ray photoelectron spectroscopy).

[0010]

Embodiments of the present invention will be described below in detail. In the present invention, a toner obtained by kneading and pulverizing a binder resin and a colorant is dispersed in a solvent in which a surfactant and a dispersion stabilizer are present, and the toner is heated into a spherical shape. Therefore, the generation of fine powder due to stress is unlikely to occur, and the surface roughness index representing the surface state of the toner is controlled within a certain range, and the amount of fine particles added to the toner particles in order to adjust the chargeability and fluidity is adjusted. An electrostatic image developing toner controlled to a specific range and a method of manufacturing the same. The “surface roughness index” of the toner specified in the present invention is used to represent the surface state of particles,
It is represented by the ratio of ET specific surface area / spherical specific surface area. The BET specific surface area can be easily measured by a nitrogen adsorption method using a beta soap automatic surface area meter (manufactured by Nikkiso Co., Ltd.). The spherical equivalent specific surface area is obtained by calculating the toner from a particle size distribution measured by a Coulter counter, assuming that the particles are truly spherical. When the index is high, the particle surface has a complicated shape, and when the index is low, the particle surface has a smooth shape. In the present invention, the above-mentioned surface roughness index needs to be specifically included in the range of 1.1 to 1.5. When the surface roughness index is smaller than 1.1, the transfer performance decreases due to an increase in the contact area with the photoreceptor. On the other hand, when the index is larger than 1.5, the contact area with the photoreceptor is reduced. Although the transfer performance does not decrease due to the decrease in toner, toner destruction and deformation due to long-term running cannot be suppressed.

In the present invention, the amount of the inorganic fine particles added for imparting chargeability, fluidity and the like to the toner particles is determined by the amount of the X-ray photoelectron spectrometer (XP
In the coverage measurement by S), the ratio of the inorganic fine particles adhering to the toner particle surface needs to be in the range of 30 to 50%. The coverage measurement by XPS is an X-ray photoelectron spectrometer (JPS-80, manufactured by JEOL Ltd.)
Is measured by measuring the ratio of the inorganic fine particles adhering to the toner surface (the ratio of the surface adhering area) to the entire toner particle surface. If the ratio of the inorganic fine particles adhering to the surface of the toner particles is less than 30%, there is a problem in the chargeability, fogging occurs, which is not preferable in terms of image quality, and the transferability deteriorates, and the resolution and fine line reproduction are reduced. It is not preferable because high quality cannot be obtained due to deterioration of properties and the like. On the other hand, when the ratio is more than 50%, the chargeability and transferability are good, but the added fine particles are detached and scattered during long-term running, so that the carrier,
Contamination of the sleeve and the photoconductor occurs, which causes image quality defects such as poor electrification, blackening and white stripes. By controlling the ratio (coverage) of the inorganic fine particles adhering to the toner surface to 30 to 50%, the amount of the inorganic or organic resin fine particles added can be suppressed to a small range.

A conventionally known method can be applied to the method for producing a toner in the present invention. First, a wet sphering method in which toner particles are stirred and dispersed in water and heated to maintain the temperature above the glass transition point of the thermoplastic resin, whereby spheroidization proceeds depending on temperature and time.
In this method, in order to prevent coalescence of the toner particles to each other at the time of dispersion, a water-soluble polymer over as a dispersion stabilizer.
In addition, the surface condition of the whole toner in this method depends on the temperature and time for heating and the temperature and time for drying, whereby a sample having a desired shape can be obtained. The surface of the toner, depending on the kind and amount of the dispersion stabilizer, an inorganic poorly soluble powder the surface properties that a rough.

In the method for producing a toner, examples of the solvent used include water, alcohol, and ketone, and it is preferable to use an aqueous medium. In this solvent, as a water-soluble polymer used as a dispersion stabilizer, for example, besides cellulose compounds such as carboxymethylcellulose and hydroxypropylcellulose, polyvinyl alcohol, gelatin, starch, gum arabic, polyethylene glycol, polypropylene glycol and the like These are usually 0.1 to 10% by weight based on the solvent.
It preferably is added in the range of.

Examples of the surfactant for dispersing the toner particles in water include anionic surfactants such as sulfates, sulfonates and phosphates, and cationics such as amine salts and quaternary ammonium salts. Nonionic surfactants such as surfactants, polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols can be used, but nonionic surfactants are particularly preferred in terms of toner spheroidization and charging properties. Preferably, an activator is used. The amount of the surfactant used is 0.001 to the solvent.
It is preferably in the range of 10 to 10% by weight.

As the binder resin used in the toner of the present invention, any known resin can be used. Specifically, thermoplastic resins, for example, styrenes such as styrene, parachlorostyrene, and γ-methylstyrene, methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, acrylic acid 2
-Ethylhexyl, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, esters having a vinyl group such as 2-ethylhexyl methacrylate, acrylonitrile, vinyl nitriles such as methacrylonitrile, vinyl methyl ether, Vinyl ethers such as vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; polymers of olefins such as ethylene, propylene and butadiene; or copolymers obtained by combining two or more of these. Or a mixture thereof, furthermore, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide resin, a cellulose resin, a polyether resin, etc., a non-vinyl condensed resin, The mixtures and graft polymers obtained by polymerizing a vinyl monomer under these coexistence may be used.

Examples of the colorant used in the toner include carbon black, chrome yellow, Hansa yellow, benzidine yellow, slen yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, and permanent red. Brilliantamine 3B, Brilliantamine 6B, Dupont Oil Red, Pyrazolone Red, Risor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, acridine, xanthene, azo, benzoquinone, azine, Torakinon, dioxazine,
Thiazine-based, azomethine-based, indigo-based, thioindigo-based, phthalocyanine-based, alinine black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, thiazine-based, thiazole-based, and various dyes such as xanthene-based dyes. Two or more kinds can be used in combination.

In the toner of the present invention, a magnetic substance, a charge control agent, a release agent, and the like can be added as an internal additive to the binder resin and the colorant, if necessary. Examples of the magnetic material include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and magnetic materials such as compounds containing these metals. As the charge control agent, quaternary ammonium Salt compounds,
Examples of the dye include a known dye such as a nigrosine compound, a complex of aluminum, iron, and chromium, and a triphenylmethane pigment. As the release agent, for example, polyethylene, polypropylene, low molecular weight polyolefins such as polybutene, silicones softened by heating, oleamide, erucamide,
Fatty acid amides such as ricinoleamide, stearamide, etc., carnauba wax, rice wax,
Minerals such as plant waxes such as candelilla wax, wood wax, jojoba oil, etc., animal waxes such as beeswax, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc., petroleum-based wax,
And modifications thereof can be used.

[0018]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 90 parts by weight of polyester resin (Sanyo Kasei Mn = 4000, Mw = 50000 Tg = 65 ° C.) 10 parts by weight of carbon black The above components were kneaded by a Banbury mixer, then finely pulverized by a jet mill, and averaged in particle size. An 8 μm toner was obtained. Observation of the shape of this toner with a scanning electron microscope revealed that the toner was an irregular-shaped toner having no regularity. 200 parts by weight of this toner was mixed with 0.1% by weight of polyoxyethylene nonyl phenyl ether as a nonionic surfactant and 3.0% by weight in water in which 2.0% by weight of gum arabic was dissolved.
The mixture was dispersed in 0 parts by weight and stirred by a three-one motor for 30 minutes until it was uniformly wetted. Thereafter, the mixture was heated to 88 ° C. in one hour while stirring in a water bath, kept in this state for further 30 minutes, stopped heating, poured water into the water bath, and cooled to 25 ° C. in two hours. Further, the pure water washing treatment by suction filtration was repeated 5 times, followed by drying in a drier at 20 ° C. for 7 hours, crushing, and sieving through a 43 μm net to obtain a toner. The obtained toner had an average particle size of 8.8 μm and was observed to be substantially spherical when observed with a scanning electron microscope. The shape roughness index of the spherical toner was 1.10. Hydrophobic silica was added to the toner with a Henschel mixer in an amount of 0.1%.
38% by weight was externally added. The coverage was measured by XPS and found to be 49.5%.

Example 2 200 parts by weight of the polyester irregular-shaped toner used in Example 1 were dissolved in 0.1% by weight of polyoxyethylene nonylphenyl ether and 2.0% by weight of gum arabic as nonionic surfactants. Dispersed in 3,000 parts by weight of water and 30
Minutes. Thereafter, the mixture was heated to 88 ° C. in one hour while stirring in a water bath, kept in this state for another 10 minutes, stopped heating, poured water into the water bath, and cooled to 25 ° C. in two hours. Furthermore, the pure water washing treatment by suction filtration was repeated 5 times, and then dried at 30 ° C.
, Dried for 5 hours, crushed, and sieved with a 43 μm mesh to obtain a toner. The resulting toner has an average particle size of 8.
When observed with a scanning electron microscope, it was observed that the particles were almost spherical. The shape roughness index of this spherical toner was 1.30. 0.41% by weight of hydrophobic silica was externally added to this toner using a Henschel mixer. When the coverage was measured by XPS, it was 48.5.
%Met.

[0020]

Example 3 To the spherical toner obtained in Example 1, 0.24% by weight of hydrophobic silica was externally added using a Henschel mixer. The coverage was measured by XPS and found to be 30.7%.

Comparative Example 1 200 parts by weight of the polyester irregular-shaped toner used in Example 1 were dissolved in 0.1% by weight of polyoxyethylene nonylphenyl ether and 2.0% by weight of gum arabic as nonionic surfactants. Dispersed in 3,000 parts by weight of water and 30
Stirred for minutes. Thereafter, the mixture is heated to 90 ° C. for 1 hour with stirring in a water bath, and then further heated to 60 ° C.
After holding for 1 minute, heating was stopped, water was put into a water bath, and the temperature was cooled to 25 ° C. in 2 hours. Further, pure washing by suction filtration was repeated 5 times, then dried with a vacuum drier, crushed, and sieved with a 43 μm mesh to obtain a toner. The obtained toner had an average particle size of 8.9 μm and was observed to be almost spherical when observed with a scanning electron microscope. The shape roughness index of this spherical toner is 1.05
Met. 0.36% by weight of hydrophobic silica was externally added to this toner using a Henschel mixer. The coverage was measured by XPS and found to be 48.9%.

Comparative Example 2 200 parts by weight of the polyester irregular-shaped toner used in Example 1 was dissolved in 0.1% by weight of polyoxyethylene nonylphenyl ether and 2.0% by weight of gum arabic as nonionic surfactants. Dispersed in 3,000 parts by weight of water and 30
Stirred for minutes. Thereafter, the mixture was heated to 70 ° C. in one hour while stirring in a water bath, the heating was stopped in that state, water was poured into the water bath, and the mixture was cooled to 25 ° C. in two hours. Further, after the pure water washing treatment by suction filtration was repeated 5 times, the product was dried at 40 ° C. for 2 hours with a drier, crushed, and sieved with a 43 μm mesh to obtain a toner. The obtained toner had an average particle size of 9.0 μm, and was observed by a scanning electron microscope to be slightly distorted rather than spherical. The shape roughness index of this toner is 1.
80. 0.48% by weight of hydrophobic silica was externally added to the toner with a Henschel mixer. The coverage was measured by XPS and found to be 47.5%.

Comparative Example 3 The shape roughness index of the polyester-based irregular-shaped toner used in Example 1 was measured, and the measured value was 4.50. This was used as it was, and hydrophobic silica was externally added by 0.65% by weight using a Henschel mixer. The coverage was measured by XPS and found to be 40.5%. Comparative Example 4 Hydrophobic silica was externally added to the spherical toner obtained in Example 1 by a Henschel mixer at 0.21% by weight. The coverage was measured by XPS and found to be 25.7%. Comparative Example 5 To the spherical toner obtained in Example 1, 0.57% by weight of hydrophobic silica was externally added using a Henschel mixer. The coverage was measured by XPS and found to be 63.5%.

(Method of Measuring and Evaluating Toner) The toner obtained in each of the above Examples and Comparative Examples was mixed with a carrier by a V-type blender to prepare a developer. As this carrier, an acrylic coated carrier (average particle size 80 μm)
m, manufactured by Fuji Xerox Co., Ltd.) and the toner concentration is 5% by weight.
Were mixed so that This developer was put into a copying machine (Able1302μ modified M / C, manufactured by Fuji Xerox Co., Ltd.), and measured and evaluated for initial transfer efficiency, transferability and cleaning property in an environment of Bzone (20 ° C., 50RH%). Was done. (1) The transfer efficiency was measured by the ratio (percentage) of the density of the untransferred image to the density of the transferred image. Evaluation of transfer efficiency
The transfer efficiency at each image density (changed by the development bias) was measured and compared with the transfer efficiency for a fixed transfer image density (ID = 0.7). (2) The cleaning property is that the image density 0.7 ±
When the solid was developed at 0.1 and the photoreceptor was rotated once, the following judgment was made. …: No residual toner, suitable for blade cleaning. ×: Residual toner is present and blade cleaning is not suitable. (3) The charge stability is high temperature and high humidity (Azone, 28 ° C, 9
(RH%) environment, the charge amount of the developer on the magnetic roll was measured by a blow-off tribo apparatus (manufactured by Toshiba Chemical Corporation) at the beginning of image formation and after 50,000 sheets, and the degree of reduction was measured. It was determined by ○
... The change in charge amount is 5 μc / g, Δ ... 5 to 10 μc / g,
×: represents 10 μc / g or more. (4) The amount of fine powder was measured at low temperature and low humidity (Czone, 10 ° C, 3
A running test was performed in an environment of 0 RH%), and the number of fine particles having a particle size of less than 5 µm was counted by a Coulter counter at the beginning of image formation and after 50,000 sheets. …: Increase rate from the beginning is less than 5%, △ ... Increase rate from the beginning is 5-1
0%, x: The rate of increase from the initial stage exceeds 10%. Table 1 shows the above results.

[0026]

[Table 1]

[0027]

According to the present invention, the kneaded and pulverized toner is dispersed in a solvent in the presence of a surfactant and a dispersion stabilizer to form a heated sphere, thereby making it difficult to generate fine powder due to stress in a developing machine. In addition, by controlling the surface roughness index representing the surface state to a certain range, and controlling the amount of fine particles added to the toner particles for charging and fluidity control to a certain range, mechanical shock resistance can be improved. , High transferability,
An excellent toner that has blade cleaning suitability and does not cause contamination of a member such as a photoconductor and a sleeve and a carrier for a long period of time can be manufactured. The electrostatic image developing toner obtained by the present invention has extremely high transfer efficiency, has good transferability and blade cleaning suitability, exhibits a stable charging potential over a long period of time, and has fine line reproducibility without image defects. It maintains excellent high-quality image quality.

Continuation of the front page (56) References JP-A-4-211273 (JP, A) JP-A-4-337738 (JP, A) JP-A-7-104503 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) G03G 9/08-9/097

Claims (2)

(57) [Claims] 1. A step of melt-kneading a toner raw material containing a binder resin and a colorant, a step of pulverizing the melt-kneaded product, and a step of dispersing the obtained toner particles in a solvent with a surfactant and a dispersion stabilizer.
The toner is made into a spherical shape by heating in the presence of an agent and has a toner surface roughness index of 1.
A step of forming toner particles in the range of 1 to 1.5; adding an inorganic fine powder to the toner particles;
A method for producing a toner for developing an electrostatic image, comprising a step of forming toner particles having an inorganic fine powder coverage of 30 to 50% by a linear photoelectron spectrometer (XPS). 2. An electrostatic image developing toner formed by the method according to claim 1.