JP2001194825A - Electrostatic charge image developing toner external additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external additive for toner which causes no reaction and no interaction with an organic photoreceptor and consequently causes no deterioration and no crack of the photoreceptor, which has excellent flowability and consequently causes no sticking of the toner to the photoreceptor and which has electrostatic chargeability independing on environmental condition. SOLUTION: The electrostatic charge image developing toner external additive is distinguished by being consisting of fine silica particles obtained by treatment of spherical hydrophobic fine silica particles which satisfies conditions (i) and (ii) described below, of which average grain size of primary particles is 0.01 to 5 μm, by a compound selected from a group composed of a quaternary ammonium salt compound, a floroalkyl group-containing betaine compound and a silicone oil. (i) When the fine silica particles are blended with an organic compound which is liquid at room temperature and has 1 to 40 F/m dielectric constant at 5:1 weight ratio and are shacked, the fine silica particles uniformly disperse into the organic compound. (ii) When the fine silica particles are kept at 100 deg.C for 2 hours after evaporating metyanol by an evaporator under heating from a dispersion obtained by dispersing the fine silica particles into methanol, ratio of primary particle quantity left as the primary particle to primary particle quantity present at first is >=20%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner external additive used for developing an electrostatic image in electrophotography, electrostatic recording and the like. The present invention relates to an external additive for a small particle size toner used for improving image quality.

[0002]

2. Description of the Related Art Dry developers used in electrophotography and the like are:
When one component developer uses a toner in which a colorant is dispersed in a binder resin itself and a two-component developer in which a carrier is mixed with the toner, and a copying operation is performed using these developers. In order to have process compatibility, it is necessary that the developer has excellent fluidity, anti-caking properties, fixing properties, charging properties, cleaning properties, and the like.
In particular, in order to improve fluidity, anti-caking properties, fixing properties, and cleaning properties, inorganic fine powders are often added to toners.

[0003] However, the inorganic fine powder has a large effect on charging. For example, in the case of a silica fine powder that is generally used, the negative polarity is strong, and particularly, the chargeability of the negatively chargeable toner is excessively increased under low temperature and low humidity,
On the other hand, under high temperature and high humidity, there is a problem that a large difference is caused between the two types of chargeability because the chargeability is reduced by taking in moisture. As a result, poor density reproduction,
Sometimes it caused background fog. In addition, the dispersibility of the inorganic fine powder also has a large effect on the toner properties, and when the dispersibility is non-uniform, the desired properties cannot be obtained for the fluidity and anti-caking properties, or the cleaning becomes insufficient. In some cases, toner sticking or the like occurs on the photoreceptor, causing black spot-shaped image defects.

For the purpose of improving these points, various proposals have been made to use inorganic fine powders which have been surface-treated. For example, JP-A-46-5782, JP-A-48-47345, and JP-A-48-47346 describe that the surface of silica fine powder is subjected to a hydrophobic treatment. However, a sufficient effect is not necessarily obtained only by using these inorganic fine powders.

Also, Japanese Patent Application Laid-Open Nos. 49-42354 and 55-2
No. 6518 describes that a powder of silica or the like is treated with silicone oil. However, the toner to which such surface-treated silica is added has a problem in that the offset resistance is reduced and the toner adheres to the heating roll to stain the next copy. This occurs because when the wax added to impart releasability to the toner and the silica-treated silica fine powder are mixed, the wax thickens and inhibits the releasing effect.

As a method for relaxing the strong negative charging property of the silica fine powder, a method of treating the surface of the silica fine powder with an amino-modified silicone oil (JP-A-64-73354),
A method of surface-treating silica fine powder with aminosilane and / or amino-modified silicone oil (JP-A-237561), a method of surface-treating silica fine powder with a quaternary ammonium salt (JP-A-5-004711), silica There is known a method of surface treating fine powder with an amphoteric surfactant (Japanese Patent Application Laid-Open No. 6-95426). However, treatment with these compounds
Although excessive charging rise of the negatively chargeable toner can be suppressed,
The environmental dependency of the silica fine powder itself cannot be sufficiently improved. In other words, although it is possible to slightly suppress the excessive negative chargeability of the silica fine powder after long-term use under low temperature and low humidity, similar charge neutralization occurs even during long-time use under high temperature and high humidity, As always, the environment dependency is not improved. In addition, when silicone oil is used as a treating agent, there is a disadvantage that silica is agglomerated during the treatment due to its high viscosity and powder fluidity is deteriorated.

Further, when an organic photoreceptor is used or a toner having a smaller particle size is used to achieve higher image quality, sufficient performance cannot be obtained with the above-mentioned inorganic fine powder. The organic photoreceptor has a softer surface and higher reactivity than the inorganic photoreceptor, so that its life is likely to be shortened. Therefore, when such an organic photoreceptor is used, the photoreceptor is liable to be deteriorated or scraped by the inorganic fine powder added to the toner. When the toner has a small particle size,
Since the powder fluidity is poor compared to the toner of the commonly used particle size, a large amount of inorganic fine powder must be added and used, but as a result, the inorganic fine powder may cause toner adhesion to the photoconductor. There was something.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the photoreceptor from being deteriorated or chipped because there is no reaction or interaction with the organic photoreceptor. It is an object of the present invention to provide an external additive for toner composed of silica fine particles having a chargeability that is not dependent on environmental conditions and does not cause toner adhesion to the toner.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the average particle size of the primary particles satisfying the following conditions (i) and (ii) is 0.01 to 0.01. An electrostatic charge comprising silica fine particles obtained by treating spherical hydrophobic silica fine particles of 5 μm with a compound selected from the group consisting of a quaternary ammonium salt compound, a fluoroalkyl group-containing betaine compound, and silicone oil. It has been found that a toner external additive for image development solves this problem. (i) When an organic compound which is liquid at room temperature and has a dielectric constant of 1 to 40 F / m and silica fine particles are mixed at a weight ratio of 5: 1 and shaken, the silica fine particles are contained in the organic compound. Disperse evenly. (ii) After the methanol was distilled off from the dispersion in which the silica fine particles were dispersed in methanol by heating with an evaporator, 100 ° C
At the same temperature for 2 hours, remain as primary particles 1
20% ratio of primary particles to primary particles
That is all.

Further, the surface-treated silica-based fine particles of the present invention have a highly hydrophobic surface, do not have any reactive groups such as silanol groups, and have high dispersibility, low cohesion and good fluidity. An object of the present invention is to give good results to the effects.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrophobic silica fine particles used in the present invention have R ² Si on the surface of hydrophilic silica fine particles comprising SiO ₂ units.
0 _3/2 units (where R ² is a substituted or unsubstituted carbon atom having 1 to
20 monovalent hydrocarbon group) introduced R ¹ ₃ SiO _1/2 to the resulting hydrophobic silica fine particle surface by the steps of units (wherein, R ¹ is a substituted or unsubstituted carbon atoms 1 to the same or different 6 in 1
(Hydrogenated hydrocarbon group) and spherical hydrophobic silica fine particles having an average particle size of 0.01 to 5 μm.

One example of a method for producing the above-mentioned hydrophobic silica fine particles is as follows. One selected from silane compounds represented by the general formula (I) Si (OR ³ ) ₄ (where R ³ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms) or a hydrolyzate thereof; Or a step of obtaining a dispersion of hydrophilic silica fine particles by hydrolyzing and condensing two or more compounds in a mixed solution of a hydrophilic solvent such as methanol or ethanol, water and a basic compound such as ammonia or an organic amine; Adding water to the resulting dispersion of hydrophilic silica fine particles, distilling off the hydrophilic solvent, converting the dispersion to an aqueous dispersion, and completely hydrolyzing the alkoxy groups remaining on the surface of the fine particles;
The aqueous dispersion of hydrophilic silica fine particles treated in this manner has the general formula (II) R ² Si (OR ⁴ ) ₃ (where R ² is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ is The same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms) or a hydrolyzate thereof.
Adding one or more compounds to coat the surface of the hydrophilic silica fine particles to obtain hydrophobic silica fine particles; adding a ketone-based solvent to the hydrophobic silica fine particle aqueous dispersion and distilling water to obtain a hydrophobic silica fine particle; step into a silica fine particle ketone solvent dispersion; and a hydrophobic fine silica particles ketone solvent dispersion, the general formula _{^{(III): R 1 3 SiNHSiR}} 1 3 ( where the carbon atom of R ¹ may be the same or different silazane compound represented by the number 1 to 6 monovalent hydrocarbon group), and the general formula _{^{(IV): R 1 3 SiX}} ( where, R ¹ is the general formula (III) the same .X the OH group or a hydrolyzable The compound is selected from the group consisting of a silane compound represented by the formula (I) and a step of trialkylsilation of the silanol group remaining on the surface of the silica fine particles, followed by a highly hydrophobic treatment.

Specific examples of the tetrafunctional silane compound represented by the general formula (I) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Also,
Specific examples of the partially hydrolyzed condensate of the tetrafunctional silane compound represented by the general formula (I) include methyl silicate, ethyl silicate and the like.

The hydrophilic organic solvent is not particularly limited as long as it can dissolve the compound of the formula (I) or its partially hydrolyzed condensate and water. Examples thereof include alcohols, methyl cellosolve, ethyl cellosolve, butyl cellosolve and cellosolve acetate. And ketones such as acetone and methyl ethyl ketone, and ethers such as dioxane and tetrahydrofuran. Alcohols are preferable. The alcohols of the general formula (V): R ⁶ 0H (where, R ⁶ is a monovalent hydrocarbon group having 1 to 6 carbon atoms) include an alcohol solvent represented by the specific examples include methanol, ethanol , Isopropanol, butanol and the like. When the number of carbon atoms in the alcohol increases, the particle size of the silica fine particles increases, so it is desirable to select the type of alcohol according to the target particle size of the silica fine particles.

Examples of the basic compound include ammonia, dimethylamine, diethylamine and the like, with ammonia being preferred. After dissolving a required amount of these basic compounds in water, the resulting aqueous solution (basic water) may be mixed with a hydrophilic organic solvent.

The amount of water used at this time is preferably 0.5 to 5 mol per 1 mol of the alkoxy group contained in the silane compound of the general formula (I) or the partial hydrolysis condensate thereof. The ratio of the organic solvent is preferably 0.5 to 10 by weight, and the amount of the basic compound is 0.01 to 1 per mol of the alkoxy group contained in the silane compound of the general formula (I) or the partial hydrolysis condensate thereof. Preferably it is 1 mole.

For hydrolysis and condensation of the tetrafunctional silane compound of the general formula (I), the tetrafunctional silane compound of the general formula (I) is dropped into a mixture of water and a hydrophilic organic solvent containing a basic compound. This is performed by a known method.

In order to convert the dispersion medium of the silica fine particle mixed solution dispersion into water, for example, an operation of adding water to the dispersion and distilling off the hydrophilic organic solvent is performed (this operation is repeated as necessary). be able to. The amount of water added at this time is 0.5 to 2 times, preferably almost 1 time, in terms of the weight ratio of the total amount of the used hydrophilic organic solvent and the generated alcohol.

Specific examples of the trifunctional silane compound represented by the general formula (II) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, and n-propyltrimethoxysilane. Trialkoxysilanes such as -propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, and partial hydrolysis thereof. Condensates may be used.

The amount of trifunctional silane compound represented by the general formula (II), Si0 ₂ units per mole 1~O.001 mole of hydrophilic silica fine particles used contains, preferably 0.1
It is better to use O.01 mol.

In the step of converting the dispersion medium of the aqueous dispersion of hydrophobic silica fine particles into a ketone-based solvent, an operation of adding a ketone-based solvent to the dispersion and distilling off water (repeatedly, if necessary) is performed. Will be The amount of the ketone solvent added at this time is a weight ratio with respect to the hydrophilic silica fine particles used.
It is preferable to use 0.5 to 5 times, preferably 1 to 2 times. Specific examples of the ketone solvent used here include methyl ethyl ketone, methyl isobutyl ketone, acetylacetone and the like, and preferably methyl isobutyl ketone.

Specific examples of the silazane compound represented by the general formula (III) include hexamethyldisilazane,
Specific examples of the monofunctional silane compound represented by the general formula (IV) include trimethylsilanol, monosilanol compounds such as triethylsilanol, trimethylchlorosilane,
Examples include monochlorosilane such as triethylchlorosilane, monoalkoxysilane such as trimethylmethoxysilane and trimethylethoxysilane, monoaminosilane such as trimethylsilyldimethylamine and trimethylsilyldiethylamine, and monoacyloxysilane such as trimethylacetoxysilane.

[0023] These usage, Si0 ₂ units per mole 0.1~O.5 mol hydrophilic fine silica particles used contains, and it is preferably used 0.2 to 0.3 moles.

The hydrophobic silica fine particles thus produced can be obtained as a powder by a conventional method.

The particle size of the fine particles is from 0.01 to 5 μm, preferably from 0.05 to 0.5 μm, from the viewpoint of improving the fluidity, anti-caking property and fixing property of the developer and reducing the adverse effect on the photoreceptor. It is. If the particle size is less than 0.01 μm, the fluidity, caking resistance and fixability of the developer cannot be obtained due to agglomeration, and if it exceeds 5 μm, disadvantages such as denaturation of the photoreceptor, shaving, and reduced adhesion to the toner will occur.

The hydrophobic silica fine particles are surface-treated with a treating agent selected from a quaternary ammonium salt compound, a fluoroalkyl group-containing betaine compound and silicone oil.

The quaternary ammonium salt compounds used in the present invention include, for example, compounds represented by the following general formulas (VI) and (VII) and bipyridyl compounds obtained by dimerizing the compound of the general formula (VII) Can be exemplified.

General formula (VI): R ⁷ R ⁸ R ⁹ R ¹⁰ N ⁺ X (where R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same or different and may have 1 to 20 carbon atoms which may be substituted) X is a monovalent anion.) General formula (VII):

[0029]

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(Provided that R ¹¹ is the same or different and may be substituted monovalent hydrocarbon group having 1 to 20 carbon atoms and X is a monovalent anion.) More specifically, benzyltriethylammonium Chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, benzyldimethylphenylammonium chloride, benzyldimethyltetradecylammonium chloride, phenyltrimethylammonium chloride, benzyltriethylammonium 4-hydroxy-1-naphthalenesulfonide, 1,1′-di Octadecyl-4,4'-
Compounds such as bipyridium dibromide are exemplified. Among these, preferred compounds are benzyltriethylammonium chloride and benzyltriethylammonium 4-hydroxy-1-naphthalene sulfonide.

As the betaine compound having a fluoroalkyl group used in the present invention, for example, a compound represented by the following general formula (VIII) can be exemplified. General formula (VIII):

[0032]

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(Where CnFm- represents an alkyl group or an alkenyl group, n is an integer of 1 to 20, and m is 2n + 1 or 2
a n-1, l is an integer of 1 to 10, R ¹² and R ¹³
Are the same or different and may be substituted with 1 to 20 carbon atoms.
R ¹⁴ is the same or different monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted, and Y ¹⁴
Represents a single bond or -O-, a phenylene group, -S0
_{2 -, - CO -, -} NR 15 - 2 ( wherein, R ¹⁵ is having the same meaning as R ^14.) Are formed in combination of 2 or more groups selected group or from those selected from Is a valence group.

More specifically, C ₈ F ₁₇ N ⁺ (CH ₃ ) ₂ CH ₂ CO
Compounds such as O ⁻ , C ₁₀ F ₂₁ N ⁺ (CH ₃ ) ₂ CH ₂ COO ⁻ , and C ₁₂ F ₂₅ N ⁺ (CH ₃ ) ₂ CH ₂ COO ⁻ are exemplified. Preferably, C ₈ F ₁₇ N ⁺ (CH ₃ ) ₂ CH ₂
COO ^- it is.

The silicone oil used in the present invention includes dimethyl silicone oil and modified silicone oil represented by the following general formula (IX).

General formula (IX):

[0037]

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(Where R is an alkyl group having 1 to 3 carbon atoms,
R ′ are the same or different, and are alkyl, alkyl halide,
A phenyl or substituted phenyl group;
3 represents an alkyl group or an alkoxy group, and n and m
Represents an integer of 0 to 10000, but not simultaneously 0. )

In the general formula (IX), examples of the alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group and an isopropyl group, and examples of the halogenated alkyl group include 3,3,3-trialkyl. A fluoropropyl group may be mentioned, and a substituted phenyl group may be, for example, a chlorophenyl group. Examples of the alkyl group represented by R "include those exemplified for R, and examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group.

Specific examples of the silicone oil represented by the general formula (IX) include dimethyl silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil substituted with an ethyl group, propyl group and the like. Silicone oil is preferred.

As the modified silicone oil, an amino silicone oil is preferable. Amino silicone oil is obtained by introducing an amino group into silicone oil. The aminosilicone oil has the general formula (X):

[0042]

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[0043] (wherein, R is an alkyl group having 1 to 3 carbon atoms, R ⁷ is an alkylene group or a phenylene group, R ^8,
R ⁹ is the same or different and represents hydrogen, an alkyl group, an aryl group or an aminoalkyl group, and R ″ is the same or different and is an alkyl group having 1 to 3 carbon atoms, an alkoxy group, or a compound represented by the formula (XI): —R ⁷ —N (R ⁸ ) (R ⁹ ) (XI) (where R ⁷ , R ⁸ and R ⁹ are as defined above), and 1 and p are each an integer of 0 to 10000 However, when l is 0, at least one of R "is a group represented by the formula (XI). ).

In the general formula (X), R is the same as R in the general formula (IX), and examples of the alkylene group represented by R ⁷ include a methylene group, an ethylene group and a trimethylene group. Examples of the alkyl group represented by R ⁸ and R ⁹ include methyl, ethyl, propyl and the like, examples of the aryl group include a phenyl group and the like, and examples of the alkylamino group include aminoethyl and aminopropyl. As the alkyl group or alkoxy group having 1 to 3 carbon atoms represented by R ", those similar to R" in the general formula (IX) are exemplified. Representative examples of aminosilicones include KF-393, KF-859, KF-860, KF861, KF8
64 and KF865 (trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

As a surface treatment method for hydrophobic silica fine particles with a quaternary ammonium salt compound or a fluoroalkyl group-containing betaine compound, a quaternary ammonium salt compound or a fluoroalkyl group-containing betaine compound is dissolved or dispersed in an appropriate solvent such as alcohol. Then, after adding to the hydrophobic silica fine particles and coating the surface, the solvent may be distilled off and dried. At this time, the order of adding each component is not particularly limited. Further, a quaternary ammonium salt compound or a fluoroalkyl group-containing betaine compound is added to the hydrophobic silica fine particle ketone-based solvent dispersion during the production of the hydrophobic silica fine particles,
After coating the surface, the solvent may be distilled off and dried. further,
If necessary, grinding and classification may be performed after drying.

A known method is used for the above-described treatment with silicone oil. For example, fine silica powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or silicone-based silica may be used. A method of spraying oil may be used. Alternatively, it may be prepared by dissolving or dispersing a silicone oil in a suitable solvent, mixing with a base silica fine particle, and removing the solvent.

The treatment amount of the above quaternary ammonium salt compound, fluoroalkyl group-containing betaine compound or silicone oil is preferably 0.1 to 10% by weight, more preferably 0.5 to 3% by weight, based on the hydrophobic silica fine particles. is there. If the treatment amount is too large, the silica fine particles are aggregated, so that sufficient fluidity cannot be obtained, and it is economically disadvantageous. If the treatment amount is too small, a sufficient charge amount cannot be obtained.

The amount of the toner external additive to be added to the toner is usually preferably 0.01 to 20 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner. If the compounding amount is too small, the amount of toner adhering to the toner is small and sufficient fluidity cannot be obtained. If the compounding amount is too large, not only adversely affects the chargeability of the toner but also is economically disadvantageous.

The state of attachment to the toner external additive toner particle surface may be simply mechanical attachment or may be loosely fixed to the surface. Further, the toner particles may cover the entire surface or a part of the toner particles. The surface-treated inorganic compound fine particles may be partially coated as an aggregate, but are preferably coated in a single-layer particle state.

As the toner particles to which the above-mentioned toner external additives are added, known toner particles mainly composed of a binder resin and a colorant can be used. Further, a charge control agent may be added as needed.

The positive charge image developing toner to which the toner external additive of the present invention is added can be used as a one-component developer.
It can also be mixed with a carrier and used as a two-component developer. When used as a two-component developer, the toner external additive may not be added to the toner particles in advance, but may be added at the time of mixing the toner and the carrier to coat the toner surface. As the carrier, iron powder or the like, or a known material having a surface coated with a resin is used.

[0052]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 Synthesis of Spherical Hydrophobic Silica Fine Particles (Step 1) 623.7 g of methanol, 41.4 g of water, 283.7 g of water were placed in a 3-liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer.
49.8 g of aqueous ammonia was added and mixed. Add this solution to 3
1163.7g of tetramethoxysilane while adjusting to 5 ° C and stirring
And 5.4% ammonia water 418.1 g were added at the same time,
The former drip over 6 hours and the latter over 4 hours. After the dropwise addition of tetramethoxysilane, stirring was continued for 0.5 hours to carry out hydrolysis to obtain a suspension of silica fine particles. Attach an ester adapter and a cooling tube to the glass reactor, heat to 60 to 70 ° C and distill off 1132 g of methanol.Add 1200 g of water, and then further heat to 70 to 90 ° C to distill off 273 g of methanol. An aqueous suspension of fine silica particles was obtained.

(Step 2) At room temperature, 11.6 g of methyltrimethoxysilane (0.01 mol per mol of tetramethoxysilane) was added dropwise to the aqueous suspension over 0.5 hour, and the mixture was stirred for 12 hours after the addition. Then, the surface of the silica fine particles was treated.

(Step 3) After adding 1440 g of methyl isobutyl ketone to the dispersion thus obtained, the mixture was heated to 80 to 110 ° C., and 1163 g of methanol water was distilled off over 7 hours. 357.6 g of hexamethyldisilazane was added to the obtained dispersion at room temperature.
The mixture was heated to 120 ° C. and reacted for 3 hours to trimethylsilyl fine silica particles. Then the solvent is distilled off under reduced pressure
477 g of 0.12 μm spherical hydrophobic silica fine particles were obtained. The following tests were performed on the obtained hydrophobic silica fine particles.

<Dispersibility test> Fine particles were added to a liquid organic compound at room temperature in a weight ratio of 5: 1, and the mixture was shaken with a shaker for 30 minutes, and the dispersion state of the fine particles was visually observed. I do. ○: the fine particles are wet with the organic compound, but not partially dispersed in the organic compound, and Δ: the fine particles are not wetted by the organic compound. The results are shown in Table 1 as x when the two do not mix.

<Aggregation Acceleration Test> (1) Fine particles are added to methanol in a weight ratio of 5: 1, and shaken for 30 minutes using a shaker. The particle size distribution of the fine particles treated as described above is measured by a laser diffraction scattering type particle size distribution analyzer (LA910, Horiba, Ltd.). (2) Next, methanol is distilled off from the fine particle dispersion obtained in (1) by heating using an evaporator, and the mixture is kept at 100 ° C. for 2 hours.

After the fine particles treated in this manner are added to methanol and shaken for 30 minutes using a shaker, the particle size distribution is measured in the same manner as described above. The ratio of the remaining amount of the primary particles is determined based on the particle size distribution obtained in (1). The primary particle size is confirmed in advance by observation with an electron microscope. The results are shown in Table 1.

[Preparation of external additive (surface-treated silica fine particles)]
40 g of the obtained hydrophobic silica fine particles are added to 160 g of methanol and dispersed by shaking. 0.4 g of benzyltriethylammonium chloride (treatment agent A) is added to and dissolved in this dispersion. Using an evaporator, methanol as a solvent was removed and dried to obtain quaternary ammonium salt-treated silica fine particles.

<Measurement of Charge Amount of Surface-treated Silica Fine Particles>
O.5% by weight was added to ferrite as a carrier, mixed well, and triboelectrically charged. The charge amount of this sample was measured using a blow-off powder charge amount measurement device (TB-Toshiba Chemical Co., Ltd.).
200 type). The results are shown in Table 1.

[Preparation of external additive-mixed toner] Tg 60 ° C., softening point
96 parts by weight of a polyester resin at 110 ° C. and 4 parts by weight of Carmine 6BC (manufactured by Sumitomo Color Co., Ltd.) as a colorant were melt-kneaded, pulverized and classified to obtain a toner having an average particle diameter of 7 μm. To 40 g of this toner, 1 g of the above-mentioned surface-treated spherical hydrophobic silica fine particles were mixed by a sample mill to obtain an external additive-mixed toner. Using this, the degree of aggregation was evaluated by the following method.

<Measurement of agglomeration degree> The agglomeration degree is a value representing the fluidity of a powder, and is measured using a three-stage sieve in which a powder tester manufactured by Hosokawa Micron Co., Ltd. and a 200, 100, and 60 mesh sieve are sequentially stacked. It was measured. As a measuring means, a powder consisting of 5 g of toner is placed on the upper 60-mesh sieve of the three-stage sieve, and a voltage of 2.5 V is applied to the powder tester, and the three-stage sieve is vibrated for 15 seconds. From the powder weight a (g) remaining on the sieve, the powder weight b (g) remaining on the 100-mesh sieve, and the powder weight c (g) remaining on the 200-mesh sieve according to the following formula. Calculate the degree. Cohesion (%) = (a + b × 0.6 + c × 0.2) × 100/5 The smaller the cohesion, the better the fluidity, and the higher the cohesion, the poorer the fluidity. The results are shown in Table 1.

[Preparation of Developer] Developed by mixing 5 parts of an external additive-mixed toner and 95 parts of a carrier obtained by coating a ferrite core having an average particle diameter of 85 μm with a polymer obtained by polyblending a perfluoroalkyl acrylate resin and an acrylic resin. An agent was prepared. Using this, the toner charge amount and toner adhesion to the photoreceptor were evaluated by the following methods.

<Toner charge amount>
0 ° C, 90% RH) or low temperature and low humidity (10 ° C, 15% RH)
After standing for a day, they were mixed well under the same conditions and triboelectrically charged. The charge amount of each sample was measured under the same conditions using a blow-off powder charge amount measuring device (TB-200, manufactured by Toshiba Chemical Corporation). The results are shown in Table 1.

<Evaluation of Adhesion of Toner to Photoconductor> The above developer was put into a two-component remodeled developing machine equipped with an organic photoconductor, and
A 000 print test was performed. At this time, the adhesion of the toner to the photoreceptor can be sensed as white spots in all solid images. The degree of white spots is "many" 10 or more / cm
^2, "little" one to nine / cm ^2, was evaluated as 0 / cm ² or "none". The results are shown in Table 1.

Example 2 Spherical hydrophobic particles having an average particle size of 0.30 μm were prepared in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 20 ° C. instead of 35 ° C. in the synthesis of the spherical hydrophobic silica fine particles. 467 g of functional silica fine particles were obtained. Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Spherical hydrophobic particles having an average particle size of 0.09 μm were prepared in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 40 ° C. instead of 35 ° C. in the synthesis of spherical hydrophobic silica fine particles. 469 g of functional silica fine particles were obtained. Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Examples 4 to 11 Evaluations were made in the same manner as in Example 1 except that the treating agent for spherical hydrophobic silica fine particles used was the following treating agent instead of benzyltriethylammonium chloride (treating agent A). The results are shown in Table 1. Treatment agent B: Tetramethylammonium chloride Treatment agent C: Benzyltrimethylammonium chloride Treatment agent D: Benzyldimethylphenylammonium chloride Treatment agent F: Benzyldimethyltetradecylammonium chloride Treatment agent F: Phenyltrimethylammonium chloride Treatment agent G: Benzyltriethylammonium 4-Hydroxy-1-naphthaline sulfonide Treatment agent H: 1,1'-dioctadecyl-4,4'-bipyridium dibromide Treatment agent I: Fluoroalkylbetaine (manufactured by Neos Co., Ltd., trade name: Footer) Gent 400S) Treatment agent J: Perfluoroalkyltrimethylammonium salt (manufactured by Dainippon Ink and Chemicals, Inc., trade name: Megafac F-150) Treatment agent K: Fluoroalkylammonium iodide (manufactured by Neos Co., Ltd.) (Name: Futuregent FT-300)

Comparative Example 1 Spherical silica fine particles having an average particle diameter of 0.12 μm were prepared in the same manner as in Example 1 except that the step of trimethylsilylating silica fine particles using hexamethyldisilazane in (Step 3) in Example 1 was omitted. 451 g was obtained. Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2 1000 g of water was used instead of 1200 g of water in (Step 1) in Example 1.
468 g of spherical hydrophobic silica fine particles having an average particle size of 0.12 μm were obtained in the same manner as in Example 1 except that a mixture of 1,000 g of methyl isobutyl ketone was used. Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Comparative Examples 3 to 5 Benzyltriethylammonium chloride (treatment agent) was used as a treatment agent for the spherical hydrophobic silica fine particles in Example 1.
Evaluation was performed in the same manner as in Example 1 except that the following treating agents were used instead of A). The results are shown in Table 1. Treatment agent L: dibutylaminopropyltrimethoxysilane Treatment agent M: betaine Treatment agent N: stearyl dimethyl betaine

Comparative Example 6 Nipsil SS50F prepared by treating the surface of a precipitated silica with an organosilicon compound instead of the spherical hydrophobic silica fine particles of Example 1.
Evaluation was performed in the same manner as in Example 1 except that Nippon Silica Co., Ltd. was used.

Comparative Example 7 Evaluation was performed in the same manner as in Example 1 except that Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd.) obtained by hydrophobizing fumed silica was used instead of the spherical hydrophobic silica fine particles of Example 1. .

Comparative Example 8 A toner was obtained in the same manner as in Example 1 except that the spherical hydrophobic silica fine particles of Example 1 were not added. This was evaluated in the same manner as in Example 1.

[0075]

[Table 1]

[0076]

[Table 2]

Example 14 [Preparation of External Additive (Surface Treated Silica Fine Particles)] After dispersing 100 g of the hydrophobic spherical silica fine particles synthesized in Example 1 in 400 g of toluene, dimethyl silicone oil (formula (IX)) R and R "are methyl groups, m is an integer in the range of 80 to 100, and n is 0.) (Treatment agent O)
5 g was added and mixed. The toluene was distilled off by heating to obtain 105 g of surface-treated silica fine particles.

An external additive-mixed toner was prepared in the same manner as in Example 1 except that the thus obtained surface-treated silica fine particles were used, and the degree of aggregation was measured in the same manner. Further, a developer was prepared in the same manner as in Example 1, and toner adhesion to the photoreceptor was evaluated in the same manner. Table 3 shows the results.

Example 15 Spherical hydrophobic silica having an average particle diameter of 0.30 μm was prepared in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 20 ° C. instead of 35 ° C. in the synthesis of spherical hydrophobic silica fine particles. 469 g of functional silica fine particles were obtained. Using this, surface treatment was performed with dimethyl silicone in the same manner as in Example 14, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14. The results are shown in Table 3.

Example 16 Spherical hydrophobic particles having an average particle size of 0.09 μm were prepared in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 40 ° C. instead of 35 ° C. in the synthesis of the spherical hydrophobic silica fine particles. 469 g of functional silica fine particles were obtained. Using this, surface treatment was performed with dimethyl silicone in the same manner as in Example 14, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14. The results are shown in Table 3.

Example 17 The treating agent dimethyl silicone of Example 14 was replaced with amino
Silicone (R in formula (X) is a methyl group and R "is
Xy group, R⁷Is a propylene group, R⁸Is a hydrogen atom, R ⁹Is amino
An ethyl group, having a structure in which 1 is 2 and p is 38
You. ) (Processing agent P)
Thus, surface-treated silica fine particles were obtained. Example using this
The evaluation was performed in the same manner as in No. 14. The results are shown in Table 3.

Comparative Example 9 451 g of spherical silica fine particles having an average particle size of 0.12 μm were prepared in the same manner as in Example 14 except that the step of trimethylsilylation of silica fine particles using hexamethyldisilazane in (Step 3) in Example 1 was omitted. I got Using this, surface treatment was performed with dimethyl silicone in the same manner as in Example 1, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14.
The results are shown in Table 4.

COMPARATIVE EXAMPLE 10 In step 1 of Example 1, the mixture was heated to 60 to 70 ° C. to distill off methanol, and instead of 1200 g of water added, 100 g of water was added.
468 g of spherical hydrophobic silica fine particles having an average particle size of 0.12 μm were obtained in the same manner as in Example 1 except that a mixture of 0 g and 1000 g of methyl isobutyl ketone was used. Using this, surface treatment was performed with dimethyl silicone in the same manner as in Example 14, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14.
The results are shown in Table 4.

Comparative Example 11 The procedure of Example 14 was repeated except that the spherical hydrophobic silica fine particles synthesized in Example 1 were replaced with Nipsil SS50F (manufactured by Nippon Silica Co., Ltd.) in which the precipitated silica surface was treated with an organosilicon compound. Similarly, perform surface treatment with dimethyl silicone,
The obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14. The results are shown in Table 4.

Comparative Example 12 Instead of the spherical hydrophobic silica fine particles synthesized in Example 1, Nipsil SS50F (manufactured by Nippon Silica Co., Ltd.) whose precipitated silica surface was treated with an organosilicon compound was used instead of Example 17 in place of the spherical hydrophobic silica fine particles.
Surface treatment was carried out with aminosilicone in the same manner as described above, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14.
The results are shown in Table 4.

Comparative Example 13 Aerosil R972 obtained by hydrophobizing fumed silica in place of the spherical hydrophobic silica fine particles synthesized in Example 1.
A surface treatment was performed with dimethyl silicone in the same manner as in Example 14 except that (Nippon Aerosil Co., Ltd.) was used, and the obtained surface-treated silica fine particles were evaluated in the same manner as in Example 14.
The results are shown in Table 4.

Comparative Example 14 A toner was obtained in the same manner as in Example 14, except that the surface-treated fine silica particles prepared in Example 14 were not added. This was evaluated in the same manner as in Example 14. The results are shown in Table 4.

[0088]

[Table 3]

Note: MIBK: methyl isobutyl ketone, THF: tetrahydrofuran, D ₅ : decamethylcyclopentasiloxane Treatment agent O: dimethyl silicone (R ′, R ′ in formula (IX))
R "is a methyl group, m is an integer in the range of 80 to 100, and n is 0.) Treatment agent P: aminosilicone (R in the formula (X) is a methyl group and R "Is a methoxy group, R ⁷ is a propylene group, R ⁸ is hydrogen, R ⁹ is an aminoethyl group, and has a structure in which 1 is 2 and p is 38.)

[0090]

[Table 4]

[0091]

The toner external additive for developing an electrostatic image of the present invention not only enhances the fluidity, anti-caking properties, fixability and cleaning properties of the developer, but also deteriorates and scrapes the photoreceptor and removes it from the photoreceptor. The toner has an effect that the toner is not attached to the toner and the chargeability is not affected by the environmental condition.

Claims (4)

[Claims] 1. A method for preparing spherical hydrophobic silica fine particles having an average primary particle size of 0.01 to 5 .mu.m, which satisfies the following conditions (i) and (ii), comprising a quaternary ammonium salt compound and a fluoroalkyl group-containing betaine. A toner external additive for electrostatic image development, comprising silica fine particles treated with a compound selected from the group consisting of a compound and silicone oil.
(i) When an organic compound which is liquid at room temperature and has a dielectric constant of 1 to 40 F / m and silica fine particles are mixed at a weight ratio of 5: 1 and shaken, the silica fine particles are contained in the organic compound. Disperse evenly. (ii) After methanol is distilled off from a dispersion obtained by dispersing the silica fine particles in methanol by heating with an evaporator, when the mixture is kept at a temperature of 100 ° C. for 2 hours, an initial amount of primary particles remaining as primary particles is present. The ratio to the obtained primary particle amount is 20% or more. Wherein said R ² hydrophobic silica fine particles to the hydrophilic silica fine particle surface made of SiO ₂ units Si0 _3/2 units (wherein, monovalent R ² is a substituted or unsubstituted 1 to 20 carbon atoms carbide Hydrogen group)
Hydrophobic silica fine particle surface in R ¹ ₃ SiO _1/2 units obtained by introducing a (however, monovalent hydrocarbon group of R ¹ may be the same or a substituted or unsubstituted 1-6 carbon atoms heterologous) 2. The toner external additive for electrostatic image development according to claim 1, wherein the particles are spherical hydrophobic silica fine particles having an average particle diameter of 0.01 to 5 [mu] m obtained by introducing the fine particles. 3. The toner external additive according to claim 1, wherein the silicone oil is dimethyl silicone oil. 4. The toner external additive according to claim 1, wherein the silicone oil is an amino silicone oil.