JPH02238464A - Magnetic toner for developing electrostatic images - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a new toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. [Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,■t
No., Special Publication No. 42-23910, and Special Publication No. 43-
Various methods are described in Japanese Patent No. 447411, etc., but in short, they apply a uniform electrostatic charge on a photoconductive insulating layer and irradiate the insulating layer with a light image to remove the electrostatic charge. A latent image is formed, and then the latent image is developed and visualized using fine powder called toner using the relevant technology. After transferring the powder image to paper etc. as necessary, it is fixed by heat, pressure, solvent vapor, etc. This is what we do. Toners used in these developments have conventionally used fine powders in which dyes and pigments are dispersed in natural or synthetic resins. For example, particles obtained by separating a colorant into a binder resin such as polystyrene and pulverizing the particles to a size of about 1 to 30 microns are used as toner. Magnetic toner containing magnetic particles such as magnetite is used. In the case of a system using a so-called two-component developer, the toner is usually mixed with carrier particles such as glass beads or iron powder. Further, the toner is made to have a positive or negative charge depending on the polarity of the electrostatic latent image to be developed. In order to make the toner hold an electric charge, it is also possible to use the triboelectricity of the resin that is a component of the toner, but since the toner's chargeability is small with this method, the image obtained by development is prone to fogging and is unclear. It becomes something. Therefore, in order to impart desired triboelectric charging properties to the toner, dyes, pigments, and even charge control agents that impart charging properties are added to the toner. [Problems to be Solved by the Invention] Among the charge control agents known in the technical field today, as a positive charge control agent, nigrosine dye (Japanese Patent Publication No. 41
-2427 Publication), azine dye (Special Publication No. 42-16
No. 27), vinyl polymers and condensation polymers containing amino groups (Japanese Patent Publication No. 53-13284), 4
class ammonium salt (JP-A-62-192755.
JP-A-62-87974. JP-A-1+2-539
Publication No. 44, etc. On the other hand, charge control agents include
It is desirable to have a sufficient amount of triboelectric charge, little environmental variation in the amount of triboelectric charge, good storage stability, good thermal stability, and good dispersibility in the binder resin, but conventionally known There is no charge control agent that satisfies all of these requirements. Also, Special Publication No. 57-3940, Special Publication No. 58-94
No. 15, JP-A-54-84732, JP-A-Sho 5
6-46248 and JP-A-61-124955 disclose that triphenylmethane dyes and pigments obtained by turning them into lakes can be used satisfactorily in two-component nonmagnetic toners. However, many of these triphenylmethane dyes or laked pigments have low triboelectric charge and cannot be used in magnetic toners. There are also triphenylmethane dyes and laked pigments that have a sufficient amount of triboelectric charge, but toners using these tend to contaminate toner carriers such as sleeves and tend to cause fogging. An object of the present invention is to provide a positively charged magnetic toner for developing electrostatic images that solves the above-mentioned problems. A further object of the present invention is to stabilize the amount of frictional charge between toner particles or between toner and a toner carrier such as a sleeve, and to maintain a stable frictional charge at a temperature that is low. The objective is to provide a developer that can reproduce stable images that are not affected by changes in humidity. [Means and effects for solving the problems] The electrostatic image developing toner of the present invention has the general formula [! ] It is characterized by containing a compound represented by the following as a positive charge control agent. As a result of studies conducted to achieve the above object, the present inventors found that the triarylmethane-based inner salt represented by the general formula [1] has excellent positive triboelectric charging properties, and is superior to many inner salts. It was found that there was no such thermal instability. Furthermore, toners containing the compound of the present invention originally have little contamination of toner carriers such as sleeves, but by externally adding positively charged silica fine powder, this contamination was completely eliminated. This is a new effect when the charge control agent of the present invention is combined with positively chargeable silica, and the contamination of the toner carrier is not necessarily completely eliminated when used in combination with a conventionally known charge control agent. In addition, contamination of sleeves, etc. becomes more pronounced as toner particles become smaller in size, but with the combination of the charge control agent and positively chargeable silica of the present invention, even toner with a volume average particle size of 5 μm can be easily contaminated due to sleeve contamination. No such phenomenon was observed. The present invention was completed based on such knowledge. In the present invention, the general formula [! ] Examples of compounds include the following. Methods for incorporating the compound of the present invention into toner include a method of adding it inside the toner and a method of adding it externally. When internally added, the amount of the charge III control agent of the present invention is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method, and is uniquely limited. However, it is used in a range of 0.1 to 201 parts by weight, preferably 0.5 to 10 parts by weight. Also, when adding externally, resin 100! 0 for i quantity part
．． 01 to 10m parts is preferable, and it is preferable to mechanochemically fix it to the surface of the base particle. It is also possible to use conventionally known charge control agents in combination with the charge control agent of the present invention to the extent that they do not have any adverse effects. In addition, as for the silica fine powder, which is another component of the present invention, both silica fine powder produced by a dry method and a wet method can be used for sewing, but from the viewpoint of filming resistance and durability, dry method is not suitable for sewing. It is preferable to use silicate fine powder by the method. The dry method referred to here is a method for producing fine silica powder by vapor phase oxidation of a silicon halide compound. For example, this method uses the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and the basic reaction formula is as follows. SIc! a+2112+02→5102+41 Lightning Cl Also, in this manufacturing process, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with a silicon halide compound. Yes, it also includes them. On the other hand, various conventionally known methods can be used to produce the silica fine powder used in the present invention by a wet method. For example, the general reaction formula for the decomposition of sodium silicate with an acid is shown below. Na20-XSiO. + lIcj + 11.0 −
= SiO.・all20 + MaceOther methods include decomposition of sodium silicate with ammonia salts or alkali salts, generation of alkaline earth metal silicate from sodium silicate, and then decomposition with acid to form silicic acid, method of decomposing sodium silicate solution with There are methods to convert silicic acid into silicic acid through ion exchange, and methods to use natural silicic acid or silicate. The silica fine powder mentioned here can be any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate. Among the above silica fine powders, the specific surface area due to nitrogen adsorption measured by the BET method is: +os+2/g or more (especially 50~
400m27g) gives good results. As a method for obtaining positively chargeable silica fine powder, the above-mentioned untreated fine silica powder is added with at least one nitrogen atom in the side chain.
There is a method of treatment with silicone oil having more than one organo group, a method of treatment with a nitrogen-containing silane coupling agent, or a method of treatment with both. In the present invention, positively charged silica refers to silica that has a positive triboelectric charge relative to the iron powder carrier when measured by a blow-off method.

As the silicone oil having a nitrogen atom in the side chain used in the treatment of silica fine powder, a silicone oil having at least a partial structure represented by the following formula can be used. (In the formula, R represents hydrogen, an alkyl group, an aryl group, or an alkoxy group. Ra represents an alkylene group or a phenylene group, Rs, R4 represents hydrogen, an alkyl group, or an aryl group, and R6 represents a nitrogen-containing hetero The above alkyl group, aryl group, alkylene group, and phenylene group (representing a cyclic group) may have an organo group having a nitrogen atom, or may have a substituent such as a halogen within a range that does not impair chargeability. You can leave it there. Further, the nitrogen-containing silane coupling agent used in the present invention generally has a structure represented by the following formula.

R m SiY n (R represents an alkoxy group or a halogen, Y represents an amino group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+n= 4.》 Examples of the organo group having at least one nitrogen atom include an amino group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a group having a nitrogen-containing heterocyclic group. The cyclic group may be an unsaturated heterocyclic group or a saturated heterocyclic group, and each known one can be used. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the following.

The heterocyclic group used in the present invention is preferably a five-membered ring or a six-membered ring in consideration of stability.

Examples of such treatment agents include aminobutyltrimethoxysilane, aminobrobyltriethoxysilane, dimethylaminobrobyltrimethoxysilane, diethylaminobrobyltrimethoxysilane, dibrobylaminobutyltrimethoxysilane, dibutyl Aminobyltrimethoxysilane, monobutylaminobyltrimethoxysilane, dioctylaminobyltrimethoxysilane, dibutylaminobyldimethoxysilane. Dibutylaminobutylene monomethoxysilane, dimethylaminophenyltriethoxysilane. trimethoxysilyl-gamma
-Propylphenylamine. Trimethoxysilyl γ-
Probylbenzylamine, etc. Furthermore, as the nitrogen-containing heterocycle, those having the above-mentioned structure can be used. Examples of such compounds include trimethoxysilyl-γ-probylbiperidine, trimethoxysilyl-γ- Examples include provilmorpholine, trimethoxysilyl-γ-probylimidazole, etc. The application amount of these treated positively charged silica fine powders is
For 100 parts by weight of positively charged magnetic toner, O. Old ~
Effective when the amount is 20 parts by weight, particularly preferably 0.3 parts by weight.
When added in an amount of up to 5 parts by weight, it exhibits positive chargeability with excellent stability. A preferred form of addition is 0,Ol to 100 parts by weight of positively charged magnetic toner.
It is preferable that 3 parts by weight of the treated silica fine powder be attached to the surface of the toner particles.

Furthermore, the silica fine powder used in the present invention may be treated with a silane coupling agent or a treatment agent such as an organosilicon compound for the purpose of hydrophobization, if necessary, and a known method may be used. , treated with the above-mentioned processing agent that reacts with or physically adsorbs the silicate powder. Examples of such processing agents include hexamethyldisilazane, trimethylsilane,
trimethylchlorosilane, trimethylethoxysilane,
Dimethyldimethylsilane, methyltrichlorosilane, allyldimethylsilane, allyl phenyldimethylsilane, benzyldimethylchlorosilane, prommethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane Lucilan, triorganosilylbutane, trimethylsilylbutane, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisilane Siloxane, 1.3
-diphenyltetramethyldisiloxane, and dimethylborisiloxane, which has 2 to 12 siloxane units per molecule and contains one Si-bonded hydroxyl group in each unit located at the end. These can be used singly or in a mixture of two or more. Finally, the degree of hydrophobicity of the treated silica fine powder was determined to be 30 as measured by methanol titration test.
When hydrophobized so as to exhibit a value in the range of .about.80, the triboelectric charge amount of the phenomenon agent containing such fine silica powder becomes sharp and uniformly positive chargeability, which is preferable. Here, in the methanol titration test, the degree of hydrophobization of the silica fine powder having a hydrophobized surface is confirmed.

The "methanol titration test" specified herein for evaluating the degree of hydrophobicity of the treated silica fine powder is carried out as follows. The sample silica fine powder 0.2g was put into a capacity of 250-
Add to 50 mi' of water in an Erlenmeyer flask. Methanol is titrated from the puret until the entire amount of silica is wetted. At this time, the solution in the flask is constantly stirred using a magnetic cooler. The "end point" is observed when the entire amount of fine silica powder is suspended in the liquid, and the degree of hydrophobicity is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.Used in the present invention Examples of the resin used include polystyrene, polyp
- Monopolymers of styrene and its substituted products such as chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers Coalescence, styrene-methacrylic acid ester copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl Styrenic copolymers such as methyl ketone copolymer, styrene-butadiene copolymer, styrene-isobrene copolymer, styrene-acrylic nitrile-indene copolymer; polyvinyl chloride, phenolic resin, naturally modified phenolic resin,
Natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaron indene resin, petroleum-based Resin etc. can be used.

Further, crosslinked styrenic copolymers are also preferred binder resins.

Examples of comonomers for the styrene monomer in the styrenic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, and phenyl acrylate. , methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylic nitrile, acrylamide, etc. or substituted products thereof; e.g., maleic acid, maleic acid, etc. Dicarboxylic acids with double bonds and their substituted substances such as butyl acid, methyl maleate, dimethyl maleate, etc.; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc.; e.g. ethylene, propylene, butylene Vinyl monomers such as ethylene olefins such as; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Alone if 《 is used two or more times.

As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used, such as aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate,
Carboxylic acid esters having two double bonds such as ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and three or more vinyl Compounds having groups; can be used alone or as a mixture. In addition, when using a pressure fixing method, it is possible to use a binder resin for pressure fixing toner, such as polyethylene,
Examples include boribropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isobrene copolymer, linear saturated polyester, and paraffin.

Furthermore, the toner of the present invention may contain a magnetic material to form a 6-competitive toner. The magnetic materials contained in the toner of the present invention include iron oxides such as magnetite, gamma iron monoxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel, or these metals and aluminum, cobalt, Examples include alloys with metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These ferromagnetic materials preferably have an average particle size of about 0.1-1 pm, preferably about 0.1-0.5 pm, and are contained in the magnetic toner in an amount of 40-150 parts per 100 parts by weight of the resin component. Parts by weight, preferably 60 to 120 parts by weight per 100 parts by weight of the resin component. Further, in order to obtain good development characteristics, the toner of the present invention has a residual magnetization σ1 of 0.5 to 68i*u/g, preferably 1 to 5e
IIIu/g, and the saturation magnetization σ. is 1 (1~40em
u/g, and the coercive force Hc is 20 to 100 Ested (
0. ) is preferable (the measured magnetic field is IKO.).

The toner of the present invention may contain additives, if necessary. Examples of additives include detergents such as zinc stearate, abrasives such as cerium oxide and silicon carbide, flow agents such as aluminum oxide, anti-caking agents, and carbon black, tin oxide, etc. There are conductivity imparting agents.

In addition, fluorine-containing polymer fine powder such as polyvinylidene fluoride fine powder has good fluidity and polishability. This is a preferable additive from the viewpoint of charging stability.

In addition, in order to improve mold releasability during hot roll fixing, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc.
It is also one of the preferred embodiments of the present invention to add about 5% by weight to the magnetic toner.

In manufacturing the toner according to the present invention, the toner constituent materials as described above are sufficiently mixed using a ball mill or other mixer, and then thoroughly kneaded using a heat kneader such as a hot roll kneader or an extruder, and then cooled and solidified. After that, it is preferable to obtain the toner by mechanical crushing and classification; another method is to obtain the toner by splitting the constituent materials into a binder resin solution and then spray drying; Polymerization method toner manufacturing method in which monomers to be composed are mixed with predetermined materials to form an emulsified suspension and then polymerized to obtain a toner; Alternatively, in a so-called microcapsule toner consisting of a core material and a shell material, the core The following methods can be applied: a method in which a predetermined material is contained in the material, the shell material, or both. Furthermore, the toner according to the present invention can be produced by sufficiently mixing desired additives with a mixer such as a Henschel mixer, if necessary.

The toner of the present invention can be used to visualize electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. by any conventionally known means.

In the toner of the present invention, the amount of triboelectric charge between toner particles is uniform, and since the toner carrier is less contaminated by the charge control agent, the amount of triboelectricity does not decrease significantly due to continuous copying. Therefore, stable, high-quality images can always be provided. [Example 1] Hereinafter, the present invention will be specifically explained using Examples, but this is not intended to limit the present invention in any way. All parts in the following formulations are parts by weight. Example 1 The above materials were thoroughly mixed in a blender and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The resulting finely pulverized powder was classified using a fixed-wall wind classifier and the classified powder was purified. Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultra-fine powder and coarse powder using a multi-division classifier (elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd.) that utilizes the Coanda effect. A black fine powder (iifi toner) was obtained.

To 100 parts of the obtained black fine powder magnetic toner was added 0.5 part of positively charged hydrophobic dry silica (CBET specific surface area 200 m''/g) treated with a silane coupling agent having an amino group, and mixed with a Henschel mixer. The obtained magnetic toner was used in a commercially available electrophotographic copying machine NP-20.
15 (manufactured by Canon ■) to, ooo) 3! I did a photo test. Clear images with an image density of 1.39 were obtained from the beginning, and good images with an image density of 1.42 were obtained even after 10,000 sheets were used. Further, after mixing 10 parts of magnetic toner with 90 parts of iron powder (75 to 50 μ-) for 20 seconds, the amount of triboelectric charge was measured by the blow-off method. The value was 8 pc/g, which was an appropriate value.

Example 2 A black fine powder with a volume average particle diameter of 7.5 J&Il was obtained in the same manner as in Example 1 except that 3 parts of Compound Example 1 in Example 1 were replaced with 2 parts of Compound Example 0 and 80 parts of magnetite. 0.7 part of positively charged hydrophobic dry silica (BET specific surface area 130 ml''/g) treated with silicone oil having an amino group was added to 100 parts of the obtained black fine powder magnetic toner, and mixed with a Henschel mixer. A positively charged one-component magnetic toner was prepared. The obtained magnetic toner was used in a commercially available electrophotographic copying machine NP-35.
25 (manufactured by Canon ■). A clear image with an image density of 1.37 was obtained from the beginning, and even after 10,000 copies, a good image with an image density of 1.35 was obtained. Ta.

In addition, the amount of triboelectric charge by the blow-off method is +13.7pc.
/g, which was an appropriate value.

Comparative Example 1 A toner was obtained and a copying test was conducted in the same manner as in Example 1, except that 0.5 part of dry silica treated with hexamethyldisilazane was added in place of the positively charged hydrophobic dry silica of Example 1. .

The image density was as low as 0.87, resulting in an image with a lot of fog. In addition, the amount of triboelectric charge by the blow-off method is +6.31
Lc/g was significantly lower than the appropriate value.

Comparative Example 2 A black fine powder having a volume average particle diameter of 7.7 IAcm was obtained in the same manner as in Example 2 except that 2 parts of Compound Example 0 in Example 2 was replaced with 2 parts of Nigrosine Base EX.

0.7 parts of the same silica as in Example 2 was externally added to 100 parts of the obtained black fine powder to obtain a one-component magnetic toner, and the image was evaluated in the same manner as in Example 2. In the initial stage, a good image with an image density of 1.33 was obtained. However, during continuous copying, the image density gradually decreases,
The image density after copying to, ooo sheets was 1.02, and the fog was noticeable, so it could not be used for practical use. After cleaning the sleeve, an image was obtained using the same toner, and the image density was 1. 3
A good image of No. 1 was obtained, and it was confirmed that the decrease in image density due to continuous copying was caused by sleeve contamination with Nigrosine Base EX. Example 3 The above materials were thoroughly mixed in a blender and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The resulting finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder was strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classifier (Elbowjet classifier manufactured by Nippon Steel Mining Co., Ltd.) using the Coanda effect to obtain a volume average particle size of 12. A fine black powder of black powder was obtained.

100 parts of the obtained black fine powder was treated with a positively charged hydrophobic dry silica (
Add 0.6 part of BET specific surface area 300a+”/g),
They were mixed using a Henschel mixer to form a positively chargeable toner. A developer was prepared by mixing 5 parts of this black fine powder with 100 parts of iron powder carrier having an average particle size of 50 to 80 μm. Next, a negative electrostatic image is formed on the OPC photoreceptor by a conventionally known electrophotographic method, and this is developed using the above developer using a magnetic brush method to create a toner image, which is transferred to plain paper. , heat-fixed. A good image with an image density of 1.35 was obtained. Also, to
, ooo copies were made continuously, but no deterioration in image quality was observed.

Example 4 A volume average particle size of 8.3μ was prepared in the same manner as in Example 3, except that 3 parts of Compound Example ■ in Example 3 was replaced with 2 parts of Compound Example 0.
A black fine powder was obtained. 100 parts of the obtained black fine powder was treated with a positively charged hydrophobic dry silica (BET specific surface area 300"/g) treated with a silane coupling agent having an amino group.
) o. Add 8 parts and mix with a Henschel mixer.
The toner was positively charged. A developer was prepared by mixing 4 parts of this black fine powder with 100 parts of iron powder carrier having an average particle size of 40 to 60 pm. An image was then obtained in the same manner as in Example 3. A good image with an image density of 1.31 and excellent fine line reproducibility was obtained, and no deterioration in image quality was observed even after continuous copying of 10,000 sheets. [Effects of the Invention] As described above, the toner of the present invention has good durability and maintains its quality for a long period of time, so that high-quality copied images can be stably provided for a long period of time.

Claims (3)

[Claims] (1) A magnetic toner for developing electrostatic images, characterized in that a positively chargeable silica fine powder is externally added to fine powder particles containing at least a material represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (However, R^1, R^2 and R^3 represent phenylene or naphthylene which may have a substituent, and they may be the same or different. R^4 and R^5 represent an aryl group which may have a substituent, and may be the same or different. R^6 is an aryl sulfone which may have a substituent. Indicates an acid anion. X^1 and X^2 represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be the same or different.) (2) Positively charged silica fine powder has the formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R represents an alkoxy group or halogen, m represents an integer from 1 to 3,
Y represents an amino group or an organo group having at least one nitrogen atom, and n represents an integer of 1 to 3 where m+n is 4. The toner for developing an electrostatic image according to claim 1, which is treated with a silane compound represented by the following. (3) The toner for developing electrostatic images according to claim 1, wherein the positively charged silica fine powder is obtained by treating the silica fine powder with a silicone oil having an organo group or an amino group having a nitrogen atom in a side chain.