TWI804672B - Positively charged hydrophobic spherical silica particles, method for producing same, and positively charged toner composition using the positively charged hydrophobic spherical silica particles - Google Patents

Abstract

（在通式（I）中，R¹ 和R² 獨立地表示為氫原子或碳原子數1~10的直鏈狀、支鏈狀或環狀的烷基。n為0或1。）The present invention provides a silica particle for an external toner additive capable of imparting a desired positive charge polarity to a toner and stably maintaining the above characteristics for a long period of time, and a toner composition containing the silica particle thing. The positively charged hydrophobic spherical silica particles of the present invention have a primary particle median diameter (D50) of 5 to 250 nm, a D90/D10 ratio of 3 or less, and an average circular shape in a volume-standard particle size distribution. The degree is 0.8~1, and the organosilicon compound represented by the following general formula (I) is bonded on its surface.

(In the general formula (I), R ¹ and R ² independently represent a hydrogen atom or a linear, branched or cyclic alkyl group with 1 to 10 carbon atoms. n is 0 or 1.)

Description

Positively charged hydrophobic spherical silica particles, method for producing same, and positively charged toner composition using the positively charged hydrophobic spherical silica particles

The present invention relates to a positively charged hydrophobic spherical silica particle and its manufacturing method And a positively charged toner composition using the positively charged hydrophobic spherical silica particles.

In electrophotographic development, by visualizing an electrostatic latent image or by inverting Visualize electrostatic latent images to obtain high-quality images. A toner suitable for the electrophotographic development method is to mix and knead a dye or pigment as a colorant, a charge control agent, a wax as a release agent, and a magnetic material in a thermoplastic resin as a binder, and then pulverize it. , Classification, and then manufacture toner particles. In addition, in order to impart fluidity to toner particles and improve cleaning performance, an external additive composed of inorganic fine powder such as silica, titanium oxide, or alumina is usually added to the toner particles. However, these inorganic fine powders are generally rich in hydrophilicity, and may change the fluidity or charge increase property of the toner under the influence of the surrounding environmental conditions (humidity).

Therefore, in order to reduce the impact on these environmental conditions, the hydrophobizing agent is used A method of introducing charged polar groups onto the surface of these inorganic fine powders while treating the surface of these inorganic fine powders. Among these methods, especially in Patent Document 1 (Japanese Unexamined Patent Publication No. 52-135739) and Patent Document 2 (Japanese Patent Unexamined Publication No. 56-123550), a surface treatment method with an aminosilane coupling agent or the like is disclosed. A method in which metal oxides such as silica fine powder are used as external additives for positively charged toners. According to this silane treatment method, a developer exhibiting strong positive charge can be obtained through the terminal amino group of the aminosilane coupling agent.

In addition, in Patent Document 3 (Japanese Patent Application Laid-Open No. 58-216252 ), it is disclosed that A method of surface-treating hydrophobic silicon dioxide particles using both a positive charge control agent and a hydrophobic agent, and using it as an external additive for a developer; in Patent Document 4 (Japanese Patent Laid-Open No. 63-73271) and Patent Document 5 (Japanese Unexamined Patent Publication No. 63-73272) discloses a method of treating silicon dioxide fine powder with a predetermined amount of nitrogen-containing silane coupling agent and silicon oil having nitrogen atoms, and using it as a developer The method of using external additives. According to these methods, a developer exhibiting strong positive charge property can be obtained by the action of the positive charge control agent.

In addition, for example, in Patent Document 6 (Japanese Patent Application Laid-Open No. 2-66564), it is disclosed A method has been disclosed in which inorganic particles having polar groups of both negatively charged polar groups and positively charged polar groups bonded to the surface are used as an external additive of a non-magnetic one-component developing toner. According to this method, it is possible to obtain a non-magnetic one-component developing toner excellent in charge level improvement, charge increase performance, and fluidity.

In addition, in Patent Document 7 (Japanese Patent Application Laid-Open No. 11-160907), it is disclosed that an invention. Its content is that in order to obtain charge increase, durability and environmental stability, it uses dry silica fine powder with positively charged polar groups and hydrophobic groups and silicon oil with positively charged polar groups for hydrophobic The chemical treatment method of wet silica fine powder is effective. In addition, an invention is disclosed in Patent Document 8 (Japanese Patent Application Laid-Open No. 11-143111). Its content is that in order to obtain charge increase, durability and environmental stability, it uses dry silica fine powder with positively charged polar groups and hydrophobic groups and contains positively charged polar groups and fluorine-containing polar groups. A mass of wet silica fine powder method is effective. In addition, an invention is disclosed in Patent Document 9 (Japanese Unexamined Patent Application Publication No. 2007-108801). Its content is that, in order to obtain good image density and fogging resistance for a long period of time even when printing at a low printing rate has been performed, as an external additive, it contains a positively charged polar group and a hydrophobic group The positively charged toner of dry silica fine powder and wet silica fine powder surface-treated by a quaternary ammonium salt-type silane compound having a fluorine-containing negatively charged polar group is effective. [Prior art literature]

[Patent Document] Patent Document 1: Japanese Patent Application Laid-Open No. 52-135739 Patent Document 2: Japanese Patent Application Laid-Open No. 56-123550 Patent Document 3: Japanese Patent Application Laid-Open No. 58-216252 Patent Document 4: Japanese Patent Laid-Open No. 63-73271 Patent Document 5: Japanese Patent Application Laid-Open No. 63-73272 Patent Document 6: Japanese Patent Application Laid-Open No. 2-66564 Patent Document 7: Japanese Patent Application Laid-Open No. 11-160907 Patent Document 8: Japanese Patent Application Laid-Open No. 11-143111 Patent Document 9: Japanese Patent Laid-Open No. 2007-108801

[Problem to be solved by the invention] It can be seen from the above-mentioned documents that although the external additives for positively charged toners usually use aminosilane coupling agents such as aminotrialkoxysilane to treat silica, these positively charged hydrophobic spherical silica particles When used as an external toner additive, there is a problem that the aminosilane component is peeled off from the surface of the silica due to long-term contact with the carrier, and the original negative charge of the silica appears, which in turn leads to a decrease in the positive charge. . The reason is speculated that before the silanol group on the surface of silica reacts with the alkoxy group of aminosilane such as aminotrialkoxysilane, the amino group of aminosilane bonds with silicon dioxide by hydrogen bonding, etc. The silanol groups on the surface are pseudo-bonded. Therefore, the alkoxy groups of silicon dioxide and aminosilane cannot form Si-O-Si bonds, and most aminosilanes are only attached to the surface of silicon dioxide. Therefore, the object of the present invention is to provide a kind of silica particles for external toner additives that can impart desired positive charge polarity to toner and can maintain stability for a long period of time, that is, excellent positive charge retention, and silica particles containing The toner composition of the silica particles.

[Technical means to solve the problem] In view of the above problems, the present inventors conducted intensive research and found that the following positively charged hydrophobic spherical silica particles can solve the above problems, and thus completed the present invention.

That is, the present invention provides the following positively charged hydrophobic spherical silica particles, the Invention of a method for producing silica particles and a positively charged toner composition containing the same.

在通式(I)中，R¹ 和R² 獨立地為氫原子或碳原子數1~10的直鏈狀、支鏈狀或環狀的烷基，n為0或1。[1] A positively charged hydrophobic spherical silica particle, wherein the median diameter (D50) of primary particles in a volume-standard particle size distribution is 5 to 250 nm, the ratio D90/D10 is 3 or less, and the average The circularity is 0.8~1, and the organosilicon compound represented by the following general formula (I) is bonded on its surface, [Chemical formula 1]

In the general formula (I), R ¹ and R ² are independently a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and n is 0 or 1.

[2] The positively charged hydrophobic spherical silica particles according to [1], further utilizing a silazane compound represented by the following general formula (III) and a monofunctional compound represented by the following general formula (IV): Silane compounds or their mixtures are surface-treated, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In general formula (III) and general formula (IV), R ⁴ represents the same or different A substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms. In the general formula (IV), X represents a hydroxyl group or a hydrolyzable group.

在通式（I）中，R¹ 和R² 獨立地表示為氫原子或碳原子數1~10的直鏈狀、支鏈狀或環狀的烷基，n為0或1。[3] A method for producing positively charged hydrophobic spherical silica particles, wherein the positively charged hydrophobic spherical silica particles are the positively charged hydrophobic spherical silica particles according to [1] or [2] Particles, the above-mentioned manufacturing method includes the following steps (A2)~step (A4), step (A2): relative to Si atoms of 1 mole of hydrophilic spherical silica particle dispersion, 0.01~0.1 mole of the following The silazane compound represented by the general formula (III), the monofunctional silane compound represented by the following general formula (IV), or a mixture thereof is added to the hydrophilic spherical silica particle dispersion, and then R ⁴ ₃ SiO _1/2 unit is introduced on the surface of the hydrophilic spherical silica particles, thereby obtaining a dispersion of hydrophobic spherical silica particles, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) in the general formula ( III), in general formula (IV), R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon groups with 1 to 6 carbon atoms, in general formula (IV), X represents hydroxyl or hydrolyzed Reactive group, step (A3): replace the dispersion medium of the hydrophobic spherical silica particle dispersion obtained in step (A2) with a ketone solvent, and then obtain a ketone solvent dispersion of the hydrophobic spherical silica particle body, step (A4): adding an organosilicon compound represented by the following general formula (I) to the ketone solvent dispersion of hydrophobic spherical silica particles obtained in step (A3), and adding Silanol groups on the surface of hydrophobic spherical silica particles undergo phenylamination, [Chemical Formula 2]

In the general formula (I), R ¹ and R ² independently represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and n is 0 or 1.

[4] The method for producing positively charged hydrophobic spherical silica particles according to [3], wherein the hydrophilic spherical silica particle dispersion is produced by the following step (A1), step (A1): by In the presence of an alkaline substance, and in a mixed solution containing a hydrophilic solvent and water, hydrolyze and condense a tetrafunctional silane compound represented by the following general formula (II), its partially hydrolyzed condensate, or a mixture thereof to obtain Hydrophilic spherical silica particle dispersion, Si(OR ³ ) ₄ (II) In the general formula (II), R ³ represents the same or different monovalent hydrocarbon groups with 1 to 6 carbon atoms.

[5] The method for producing positively charged hydrophobic spherical silica particles according to [3] or [4], further comprising the following step (A5): step (A5): The Si atoms of the phenyl-aminated spherical silica particles are mixed with 0.01-0.3 moles of a silazane compound represented by the following general formula (III), a monofunctional silane compound represented by the following general formula (IV), or The mixture thereof is added to the dispersion of phenylaminated spherical silica particles obtained in step (A4), and the silanol groups remaining on the surface of the phenylaminated spherical silica particles Group to react, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or unsubstituted carbon In the monovalent hydrocarbon group having 1 to 6 atoms, X represents a hydroxyl group or a hydrolyzable group in the general formula (IV).

[6] A positively charged toner composition comprising the toner according to [1] or [2] positively charged hydrophobic spherical silica particles.

[Effect of the invention] The positively charged hydrophobic spherical silica particles of the present invention have a rapid charge increase and are excellent in positive charge retention over time. In addition, the toner composition containing the positively charged hydrophobic spherical silica particles of the present invention has excellent fluidity and printing properties, and these properties are less affected by changes in the surrounding environmental conditions.

（在通式（I）中，R¹ 和R² 獨立地為氫原子或碳原子數1~10的直鏈狀、支鏈狀或環狀的烷基。n為0或1。）Hereinafter, the positively charged hydrophobic spherical silica particles of the present invention will be described in detail. The positively charged hydrophobic spherical silica particles of the present invention are positively charged hydrophobic spherical particles, the median diameter (D50) of the primary particles in the volume standard particle size distribution is 5-250nm, and the D90/D10 ratio is 3 or less, and an average circularity of 0.8 to 1, and an organosilicon compound represented by the following general formula (I) is bonded to the surface. [chemical formula 3]

(In the general formula (I), R ¹ and R ² are independently a hydrogen atom or a linear, branched or cyclic alkyl group with 1 to 10 carbon atoms. n is 0 or 1.)

R ¹ and R ² independently represent a hydrogen atom or a straight-chain alkyl group with 1 to 10 carbon atoms, a branched chain alkyl group with 3 to 10 carbon atoms, or a cyclic group with 3 to 10 carbon atoms of alkyl. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl base and decyl etc. Among them, a hydrogen atom and a methyl group having a small steric hindrance are preferable because they do not hinder the reaction with the silica surface.

Specific examples of organosilicon compounds represented by general formula (I) include 2,2-dimethyl Oxy-1-phenyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-phenyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-1-phenyl-1-aza-2- Silacyclopentane, etc. As the organosilicon compound represented by the general formula (I), it is preferably 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane.

The positively charged hydrophobic spherical silica particles of the present invention have a particle volume standard The median diameter of the primary particles in the density distribution (D50: the particle diameter from the small side to the cumulative 50% particle diameter) is 5~250nm, preferably 10~200nm. If the D50 is less than 5nm, the particles will aggregate severely, which may cause the overall gelation or adhesion to the inside of the production equipment, and it will not be able to be taken out smoothly; in addition, if the D50 is greater than 250nm, it may not be able to impart good positive charge, so it is not good .

The positively charged hydrophobic spherical silica particles of the present invention are characterized in that, in volume In the standard particle size distribution, when the particle diameter from the small particle size side to the cumulative 10% is taken as D10, and the particle diameter from the small particle size side to the cumulative 90% is taken as D90, due to the ratio of D90/D10 Since it is 3 or less, the particle size distribution range is narrow. Particles having such a narrow particle size distribution are preferable since they have the advantage of being easy to control fluidity. It is better to have a ratio of D90/D10 below 2.9. In the present invention, the particle size distribution of the volume standard is measured by a dynamic light scattering method using a laser beam.

In addition, in the present invention, the circularity refers to "having a particle area equal to The circumference of the area" / "the circumference of the particle projection image". Specifically, it was calculated based on the shape obtained by an electron microscope (magnification: 100,000 times), and the circularity of 10 silica particles was averaged as the "average circularity". The average circularity of the positively charged hydrophobic spherical silica particles of the present invention is 0.8-1, preferably 0.92-1. In addition, the "spherical shape" used in the present invention includes not only true spheres but also slightly deformed spheres. It should be noted that the shape of these particles was evaluated using the circularity when the particles have been two-dimensionally projected.

The positively charged hydrophobic spherical silica particles of the present invention preferably use a silazane compound represented by the following general formula (III), a monofunctional silane compound represented by the following general formula (IV), or the like. The mixture is surface-treated positively charged hydrophobic spherical silica particles. R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) (In general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or unsubstituted carbon atoms 1 ~6 monovalent hydrocarbon groups, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group.)

In the above general formula (III) and general formula (IV), R ⁴ is preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, and more preferably a monovalent hydrocarbon group having 1 to 2 carbon atoms. As the ^monovalent hydrocarbon group represented by R, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl, preferably methyl, ethyl and propyl, methyl and Ethyl is preferred. In addition, some or all of the hydrogen atoms in these monovalent hydrocarbon groups may be substituted by halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, preferably by fluorine atoms.

Examples of the hydrolyzable group represented by X include, for example, a hydroxyl group, a chlorine atom, an alkane Oxygen, amine, acyloxy, etc., preferably alkoxy and amine, more preferably alkoxy, more preferably methoxy and ethoxy.

As the silazane compound represented by the above-mentioned general formula (III), for example, six Methyldisilazane, hexaethyldisilazane, etc., preferably hexamethyldisilazane. As the monofunctional silane compound represented by the above general formula (IV), for example, monosilanol compounds such as trimethylsilanol and triethylsilanol; trimethylchlorosilane, triethylchlorosilane Monochlorosilanes such as trimethylmethoxysilane, trimethylethoxysilane and other monoalkoxysilanes; trimethylsilyldimethylamine, trimethylsilyldiethylamine and other monoaminosilanes; Monoacyloxysilanes such as trimethylacetoxysilane, etc., preferably trimethylsilanol, trimethylmethoxysilane and trimethylsilyl diethylamine, trimethylsilanol and trimethylsilanol Methylmethoxysilane is preferred.

As an evaluation of the hydrophobicity of the positively charged hydrophobic spherical silica particles of the present invention Valence method, which is not particularly limited, for example, the hydrophobization (methanol wettability) can be calculated using the methanol wettability method (MW method). The hydrophobicity of the positively charged hydrophobic spherical silica particles of the present invention is preferably at least 60%, more preferably at least 65%, when measured by the following procedure. If the value is 60% or more, good environmental resistance can be imparted to the obtained silica particles; when the silica particles are used as a toner for electrostatic charge development, good charge can be obtained. stability.

Here, the degree of hydrophobization can be obtained by the following procedure. 1) Weigh 0.2g sample into a 200ml beaker, and add 50ml pure water. 2) Add methanol below the liquid level while under magnetic stirring. 3) The point where no sample is confirmed above the liquid level is taken as the end point. 4) Calculate the degree of hydrophobization from the amount of methanol added according to the following calculation formula. Hydrophobic degree (%)=[x/(50+x)]×100 x: amount of methanol (ml)

Hereinafter, the production method of positively charged hydrophobic spherical silica particles of the present invention Give a detailed explanation.

The positively charged hydrophobic spherical silica particles of the present invention can be obtained by, for example, going through the following steps: Obtained from steps (A2) to (A4) above. In addition, the hydrophilic spherical silica particle dispersion used as the raw material of the step (A2) can be obtained by, for example, the step (A1). Step (A1): Synthetic Steps to Obtain a Dispersion of Hydrophilic Spherical Silica Particles Step (A2): Surface treatment step by monofunctional silane compound Step (A3): Dispersion medium replacement step Step (A4): The step of anilinating the surface of hydrophobic spherical silica particles Hereinafter, each step will be described in order.

Step (A1): Synthetic step for obtaining a dispersion of hydrophilic spherical silica particles. This step is to hydrolyze and condense a tetrafunctional silane compound represented by the following general formula (II) in the presence of an alkaline substance. The compound or its mixture is hydrolyzed and condensed in a mixed solution containing a hydrophilic solvent and water to obtain a hydrophilic spherical silica particle dispersion. Si(OR ³ ) ₄ (II) (In the general formula (II), R ³ represents the same or different monovalent hydrocarbon groups with 1 to 6 carbon atoms.)

In the above general formula (II), ^R3 is a monovalent hydrocarbon group with 1 to 6 carbon atoms, preferably a monovalent hydrocarbon group with 1 to 4 carbon atoms, and more preferably a monovalent hydrocarbon group with 1 to 2 carbon atoms. good. As the ^monovalent hydrocarbon group represented by R, for example, methyl, ethyl, propyl, butyl and phenyl, etc., preferably methyl, ethyl, propyl and butyl, methyl and ethyl base is better.

Examples of the tetrafunctional silane compound represented by the above general formula (II) include, Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane, tetraalkoxysilane and tetraphenoxysilane, etc., tetramethoxysilane, tetraethoxysilane , tetrapropoxysilane and tetrabutoxysilane are preferred, and tetramethoxysilane and tetraethoxysilane are preferred. Moreover, as a hydrolysis-condensation product of the tetrafunctional silane compound represented by the said general formula (II), methyl silicate, ethyl silicate, etc. are mentioned, for example.

As the basic substance, for example, ammonia, dimethylamine, diethylamine, etc., ammonia and diethylamine Ethylamine is preferred, and ammonia is more preferred. These alkaline substances can be used by dissolving them in water in prescribed amounts.

Examples of hydrophilic solvents include methanol, ethanol, 1-propanol, 2-propanol, and and alcohols such as tertiary butanol; ethers such as tetrahydrofuran and dioxane; glycols such as diethylene glycol and dipropylene glycol, etc.

With respect to the tetrafunctional silane compound represented by general formula (II) and/or its partial hydrolysis The total amount of alkoxy groups in the condensate is 1 mol, and the amount of water used in this step is preferably 0.5-5 mol, more preferably 0.6-2 mol, and more preferably 0.7-1 mol . From the viewpoint of the affinity between the hydrophobized spherical silica particles and the mixed solvent and the ease of manufacture, the ratio of the hydrophilic solvent to water is preferably 0.5-10, and 3-9 in terms of mass ratio. It is better, 5~8 is more preferable. The amount of the basic substance is preferably 0.01-2 moles, preferably 0.02- 0.5 mole is preferable, and 0.04~0.12 mole is more preferable.

The reaction conditions of the hydrolysis condensation in this step, be 20～120 ℃ with reaction temperature, The reaction time is preferably 1-8 hours, and the reaction temperature is 20-100° C., and the reaction time is 1-6 hours.

In the dispersion of hydrophilic spherical silica particles obtained in step (A1), The concentration of the silica particles is preferably 2 to 20% by mass, more preferably 3 to 10% by mass.

In addition, as a substitute for the above step (A1) and for the hydrophilic ball used in the step (A2) A commercially available silica particle dispersion can also be used. As a commercially available product, a dispersion of hydrophilic spherical silica particles in which hydrophilic spherical silica particles are dispersed in a hydrophilic solvent such as the aforementioned alcohols can be used. In the case of using a commercially available product, the hydrophilic solvent is added or distilled so as to obtain an appropriate concentration of silica particles when used in the (A2) step, and the commercially available hydrophilic spherical silica The particle dispersion is used diluted or concentrated. The silica particle concentration in this case is the same as the silica particle concentration in the hydrophilic spherical silica particle dispersion obtained in the above step (A1), preferably 2 to 20% by mass.

Step (A2): Surface treatment step with monofunctional silane compound In this step, the hydrophilic spherical silica obtained in step (A1) is Add 0.01~0.1 mole of silazane compound represented by the following general formula (III), monofunctional silane compound represented by the following general formula (IV) or a mixture thereof to the silicon particle dispersion, and then R43SiO1/2 A step of introducing units into at least a part of the surface of the hydrophilic spherical silica particles, thereby obtaining a dispersion of hydrophobic spherical silica particles. R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) (In general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or unsubstituted carbon atoms 1~ 6 monovalent hydrocarbon groups, in the general formula (IV), X represents a hydroxyl group or a hydrolyzed group)

In the above general formula (III) and general formula (IV), R ⁴ is preferably a monovalent hydrocarbon group with 1 to 4 carbon atoms, and preferably a monovalent hydrocarbon group with 1 to 2 carbon atoms. As the ^monovalent hydrocarbon group represented by R, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl and butyl, etc., preferably methyl, ethyl and propyl, methyl and Ethyl is preferred. In addition, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, preferably fluorine atoms.

Examples of the hydrolyzable group represented by X include a hydroxyl group, a chlorine atom, an alkoxy group, Amino groups, acyloxy groups, etc. are preferably alkoxy groups and amine groups, more preferably alkoxy groups, and more preferably methoxy groups and ethoxy groups.

Examples of the silazane compound represented by the above general formula (III) include hexamethylbis Silazane, hexaethyldisilazane, etc., preferably hexamethyldisilazane. As the monofunctional silane compound represented by the above-mentioned general formula (IV), for example, monosilanol compounds such as trimethylsilanol and triethylsilanol; Chlorosilanes; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; Trimethylsilanol, trimethylmethoxysilane and trimethylsilyldiethylamine are preferred, and trimethylsilanol and trimethylmethoxysilane are preferred. Oxysilanes are preferred.

Relative to the Si atoms of the hydrophilic spherical silica particles (obtained in step (A1) In the case of obtaining a dispersion of hydrophilic spherical silica particles, which is derived from the above-mentioned general formula (II) Si atom) 1 mole, the usage amount of the compound represented by the above-mentioned general formula (III) and general formula (IV) 0.01~0.1 mole, preferably 0.03~0.08 mole. If the compound is used in an amount of less than 0.01 mole, water is distilled from the dispersion medium, and when replaced with a ketone solvent system, silica particles may not be dispersed smoothly, resulting in precipitation, which is not preferable. In addition, if the amount of the compound used is greater than 0.1 mol, the aminosilane treatment in the subsequent step may not proceed smoothly, which is not preferable.

In this step (A2), the silazane compound represented by the above general formula (III), The monofunctional silane compound represented by the above general formula (IV) or its mixture is added to the dispersion of hydrophilic spherical silica particles, and the surface treatment reaction is carried out by the monofunctional silane compound under the following reaction conditions. The reaction conditions of the surface treatment in this step (A2) are preferably reaction temperature 40-60°C, reaction time 1-10 hours, and reaction temperature 50-60°C, reaction time 2-8 hours.

Step (A3): Dispersion medium replacement step This step is to replace the dispersion medium composed of water in the hydrophobic spherical silica particle dispersion obtained in step (A2), hydrophilic organic solvents, and volatile by-products such as alcohols produced by condensation with ketones Solvent step.

Specific examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, ethyl Acyl acetone, etc., preferably methyl isobutyl ketone.

From the viewpoint of inhibiting the aggregation of silica particles, and the aminosilane in the next step Considering the concentration of the reaction system during the treatment, the amount of the ketone solvent to be added is 0.5 to 5 times the amount of the hydrophobic spherical silica particles obtained in the step (A2) in terms of weight ratio. Better, it is better to use 1~2 times the amount.

As a hydrophilic organic solvent, water in the hydrophobic spherical silica particle dispersion And methods of substituting volatile by-products such as alcohols generated by condensation with ketone solvents include, for example, methods such as concentration (atmospheric pressure or reduced pressure), ultrafiltration using a filter, and the like. Preferably, the hydrophilic organic solvent contained in the dispersion of hydrophobic spherical silica particles obtained in step (A2) and a ketone solvent having a higher boiling point than water are added to the hydrophobic spherical silica particle dispersion obtained in step (A2). Silicon particle dispersion, and the method of concentration.

（在通式（I）中，R¹ 和R² 獨立地表示為氫原子或碳原子數為1~10的直鏈狀、支鏈狀或環狀的烷基。n為0或1。）Step (A4): A step of anilinating the surface of hydrophobic spherical silica particles In this step, an organosilicon compound represented by the following general formula (I) is added to the hydrophobic particles obtained in step (A3). In the ketone solvent dispersion of the spherical silicon dioxide particles, and performing animination on at least a part of the silanol groups on the surface of the hydrophobic spherical silicon dioxide particles. [chemical formula 4]

(In the general formula (I), R ¹ and R ² independently represent a hydrogen atom or a linear, branched or cyclic alkyl group with 1 to 10 carbon atoms. n is 0 or 1.)

R ¹ and R ² independently represent a hydrogen atom or a linear alkyl group with 1 to 10 carbon atoms, a branched chain alkyl group with 3 to 10 carbon atoms, or an alkyl group with 3 to 10 carbon atoms. Cyclic alkyl. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl base and decyl etc. Among them, a hydrogen atom and a methyl group having a small steric hindrance are preferable because they do not hinder the reaction with the silica surface.

Specific examples of organosilicon compounds represented by general formula (I) include 2,2-dimethyl Oxy-1-phenyl-1-aza-2-silacyclopentane, 2-methoxy-2-methyl-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-phenyl-1-aza-2-silacyclopentane, 2-ethoxy-2-methyl-1-phenyl-1-aza-2- Silacyclopentane, etc. Among them, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane is preferred.

By using the organic silicon compound represented by the above general formula (I) to treat hydrophobic spherical On the surface of silica, positively charged hydrophobic spherical silica particles can be obtained.

The surface treatment step is preferably to use the organosilicon compound represented by the above general formula (I) Adding treatment to a mixed solution in which hydrophobic spherical silica particles are dispersed in a ketone solvent. The organosilicon compound represented by the above-mentioned general formula (I) may be used as it is, or may be added in the form of diluting the organosilicon compound in the above-mentioned ketone solvent.

With respect to the hydrophobic spherical silica particles, the organic compound represented by the above general formula (I) The amount of the silicon compound added is preferably 1-30% by mass, more preferably 5-20% by mass. If the added amount of the organosilicon compound is within such a range, the silica particles will have good positive chargeability.

After adding the organosilicon compound represented by the above general formula (I), to It is better to carry out the reaction at a temperature of 20-120°C and a reaction time of 1-8 hours, and it is better to carry out the reaction at a reaction temperature of 20-100°C and a reaction time of 1-6 hours.

The production of the positively charged hydrophobic spherical silica particles of the present invention is preferably performed through the following step (A5). Step (A5): Using a silazane compound represented by the following general formula (III) at a ratio of 0.01 to 0.3 moles relative to 1 mole of Si atoms of the phenylaminated spherical silica particles, the following The monofunctional silane compound represented by the general formula (IV) or a mixture thereof is added to the phenylaminated spherical silica particle dispersion obtained in the step (A4), and it is mixed with the remaining phenylamine The step of reacting the silanol groups on the surface of the spherical silica particles, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) (in general formula (III), general formula (IV), R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon groups with 1 to 6 carbon atoms, and in the general formula (IV), X represents a hydroxyl group or a hydrolyzed group).

The compounds represented by the above general formulas (III) and (IV) in step (A5) are Same compound as described in step (A2) above. In this step, by further triorganosilylating the silanol groups remaining on the surface of the silica particles after the above step (A4), the obtained silica particles are highly hydrophobized and have improved fluidity, thereby enabling Suppresses the formation of silica anions caused by the release of protons from residual silanol groups.

Compared to the phenylaminated spherical silica particles obtained in the above step (A4) For 1 mole of Si atoms, the amount of the compound represented by the above-mentioned general formulas (III) and (IV) is preferably 0.01-0.3 mole, more preferably 0.03-0.2 mole. Within such a range, good positive chargeability, environmental charge characteristics, and fluidity can be obtained.

In this step (A5), the silazane compound represented by the above general formula (III), A monofunctional silane compound represented by the above general formula (IV) or a mixture thereof is added to the dispersion of phenylaminated spherical silica particles obtained in step (A4), and the monofunctional silane is passed under the following reaction conditions Compounds undergo surface treatment reactions. The reaction conditions of the surface treatment in this step (A5) are preferably 40-110° C. reaction temperature and 1-10 hours reaction time, and 2-5 hours reaction time 60-100° C. reaction temperature.

After the reaction, the positively charged hydrophobic spherical silica particles were suitably Local removal of dispersion medium and volatile by-products such as alcohol can yield positively charged hydrophobic spherical silica particles.

Hereinafter, the positive charge toner composition of the present invention will be described in detail. The positively charged toner composition of the present invention contains the above-mentioned positively charged hydrophobic spherical silica particles of the present invention as an external toner additive. When the positively charged hydrophobic spherical silica particles are used as an external toner additive, the blending amount is generally 0.1 to 3 parts by mass relative to 100 parts by mass of the toner, preferably 0.3 to 2 parts by mass. Parts by mass are preferred. Within such a range, stable positive chargeability can be imparted to the toner.

As the toner particles contained in the positively charged toner composition of the present invention, Known toner particles composed of a binder resin and a colorant as main components are used. In addition, other external additives may be added as needed.

The positively charged toner composition of the present invention can be Manufacturing method to manufacture. For example, there may be mentioned a method of mixing the positively charged hydrophobic spherical silica particles of the present invention with toner particles obtained by melt-mixing, pulverizing, and classifying a binder resin, a colorant, and other additives. [Example]

Hereinafter, the present invention will be specifically described using Examples and Comparative Examples. Need to explain Yes, the following examples do not limit the present invention in any way. The particle size distribution measurement and particle shape observation of the silica particles obtained in Examples and Comparative Examples were performed under the following conditions, and the results are shown in Table 1.

[Particle size distribution] The silica particle dispersion was diluted with methanol so that the amount of the silica particles became 0.5% by mass, and was measured by using a dynamic light scattering method/laser Doppler method nano-orbital particle size distribution measuring device (Nikkiso Co., Ltd., UPA-EX150) measured the particle size distribution when irradiated with ultrasonic waves for 10 minutes. The median diameter and the ratio of D90/D10 were calculated based on the obtained volume standard particle size distribution.

[particle shape] The silica particles were observed with an electron microscope (manufactured by Hitachi, Type S-4700, magnification: 100,000 times), and the shape of the particles was confirmed. Calculate the circularity of a particle when it is projected two-dimensionally using the calculation formula "circumference length of a circle having an area equal to the area of the particle" / "circumference length of the projected image of the particle", where the circle of 10 silica particles The average value of the shape was taken as the average circularity.

[Synthesis Example 1] Synthesis of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane 255 g (1.0 mol) of N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-573) and 2.0 g of a methanol solution of sodium methoxide ( 28 mass% sodium methoxide) was added to the still, and the alcohol produced was removed by distillation, and 156 g of a colorless transparent fraction with a boiling point of 173~175°C/0.4kPa was obtained (yield: 70%) .

According to the results of the mass spectrum, ¹ H-NMR spectrum (dichloroform solvent) and IR spectrum of the obtained fraction, the obtained compound was identified as 2,2-dimethoxy-1-phenyl-1-nitrogen Hetero-2-silacyclopentane.

[Example 1] • Step (A1): Synthetic steps to obtain a dispersion of hydrophilic spherical silica particles In a 3-liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer, 793.0 g of methanol, 32.1 g of water, and 40.6 g of 28% ammonia water were added and mixed. The solution was adjusted to 34° C., and 646.5 g (4.25 mol) of tetramethoxysilane and 160.9 g of 5.4% ammonia water were added dropwise while stirring, and were added dropwise for 3 hours. After completion of the dropwise addition, stirring was continued for 0.5 hours to further hydrolyze and condense to obtain a dispersion of 1662 g of hydrophilic spherical silica particles.

• Step (A2): Surface treatment step by monofunctional silane compound Add 600 g of the hydrophilic spherical silica particle dispersion (silicon dioxide content 15% by mass, 90 g (1.5 moles)) obtained in the above step (A1) to a tank equipped with a stirrer, a dropping funnel, and a thermometer. In a 3-liter glass reactor, 12.8 g (0.08 mol) of hexamethyldisilazane was added and mixed at 25°C. The solution was heated to 60° C. and allowed to react for 3 hours, thereby performing silylation on the surface of the hydrophilic spherical silica particles.

• Step (A3): Dispersion medium replaces step 1200 g of methyl isobutyl ketone was added to the reaction vessel after the above step (A2). The ester adapter and cooling tube were installed on the glass reaction vessel, and it was heated to 80~110°C and spent 5 hours to remove 1210g of methanol and water mixture by concentration, and then obtained 592g of hydrophobic spherical dioxide Silicone particle ketone solvent dispersion (silica content: 15.2% by mass, 90 g (1.5 mol)).

• Step (A4): Phenylamination of the surface of hydrophobic spherical silica particles step Put 200 g of the hydrophobic spherical silica particle ketone solvent dispersion (silicon dioxide content 30.4 g, 0.51 mol) obtained in the above step (A3) into a 0.5 Then, 1.52 g of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane (0.007 mol, 5% by mass (relative to the mass of silicon dioxide)). It heated at 100 degreeC and made it react for 3 hours. Analysis by gas chromatography of the reaction liquid after 3 hours of reaction revealed that the peak of the reaction liquid was 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): surface treatment step again with monofunctional silane compound Further, 16.1 g (0.10 mol) of hexamethyldisilazane was added from the dropping funnel to the phenylaminated spherical silica particle dispersion obtained in the above step (A4), and the It was reacted for 3 hours under the reaction temperature conditions, and then the silylation of the surface of the phenylaminated spherical silica particles was carried out. Thereafter, the dispersion medium was distilled off under reduced pressure to obtain 32 g of phenylaminated hydrophobic spherical silica particles.

[Example 2] Except that the amount of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane in step (A4) of Example 1 was changed to 3.1 g (0.014 mol, Except for 10% by mass (relative to the mass of silica)), Example 2 was implemented in the same manner as Example 1, and 33 g of phenylaminated hydrophobic spherical silica particles were obtained.

[Example 3] • Step (A1): Synthetic steps to obtain a dispersion of hydrophilic spherical silica particles In a 3-liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer, 623.7 g of methanol, 41.4 g of water, and 49.8 g of 28% ammonia water were added and mixed. The solution was adjusted to 35°C, and 1163.7g (7.66 moles) of tetramethoxysilane and 418.1g of 5.4% ammonia water were added dropwise while stirring, and the former was added dropwise for 6 hours, and the latter was added dropwise for 4 hours. Hour. After completion of the dropwise addition, further stirring was continued for 0.5 hours to perform hydrolysis, thereby obtaining a dispersion of 2,295 g of hydrophilic spherical silica particles.

• Step (A2): Surface treatment step by monofunctional silane compound 600 g of the dispersion (silica content 20% by mass, 120 g (2 moles)) obtained in the above step (A1) was charged into a 5 liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer , 9.7 g (0.06 mol) of hexamethyldisilazane was added and mixed at 25°C. This solution was heated to 60° C. and allowed to react for 3 hours to further silylate the surface of the hydrophilic spherical silica particles.

• Step (A3): Dispersion medium replaces step 1600 g of methyl isobutyl ketone was added to the reaction vessel after the above step (A2). The ester adapter and cooling tube were installed on the glass reaction vessel, and it was heated to 80~110°C and spent 5 hours to remove 1457g of methanol and water mixture by concentration, and then obtained 751g of hydrophobic spherical silica Granular ketone solvent dispersion (silica content: 16% by mass, 120 g (2 moles)).

• Step (A4): Phenylamination of the surface of hydrophobic spherical silica particles step Put 200 g of the ketone-based solvent dispersion of hydrophobic spherical silica particles (silica content 32 g, 0.53 moles) obtained in the above step (A3) into a 0.5-liter container equipped with a stirrer, a dropping funnel, and a thermometer. In a glass reactor, 1.60 g of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane (0.007 mol, 5 mass% (relative to the mass of silicon dioxide)). This was heated to 100 degreeC, and it was made to react for 3 hours. Analysis by gas chromatography of the reaction liquid after 3 hours of reaction revealed that the peak of the reaction liquid was 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): surface treatment step again with monofunctional silane compound Further, 12.9 g (0.08 mol) of hexamethyldisilazane was added from the dropping funnel to the phenylaminated spherical silica particle dispersion obtained in the above step (A4), and the Under the reaction temperature conditions, it was reacted for 3 hours, and then the silanization of the surface of the phenylaminated spherical silica particles was carried out. Thereafter, the dispersion medium was distilled off under reduced pressure to obtain 33 g of phenylaminated hydrophobic spherical silica particles.

[Example 4] In Example 1, step (A5) was not implemented, and the dispersion medium was directly distilled off under reduced pressure after step (A4) was completed, thereby obtaining 29 g of phenylaminated hydrophobic spherical silica particles.

[Example 5] The step (A1) was replaced with a commercially available hydrophilic spherical silica particle dispersion (manufactured by Nissan Chemical Industries, Ltd., IPA-ST-L, particle diameter 45 nm, 30% by mass isopropanol dispersion).

• Step (A2): Surface treatment step by monofunctional silane compound 350 g of the above-mentioned IPA-ST-L (silica content 30% by mass, 90 g (1.5 mol)) and 250 g of isopropanol were added to a 3-liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer 12.8 g (0.08 mol) of hexamethyldisilazane was added and mixed at 25°C. This solution was heated to 60° C. and allowed to react for 3 hours to further silylate the surface of the hydrophilic spherical silica particles.

• Step (A3): Dispersion medium replaces step 1200 g of methyl isobutyl ketone was added to the reaction vessel after the above step (A2). The ester adapter and cooling tube were installed on the glass reaction vessel, and it was heated to 80~110°C and spent 5 hours to remove 1220g of isopropanol by concentration, and then obtained 575g of hydrophobic spherical silica particles Solvent-like dispersion (silica content: 15.6% by mass, 90 g (1.5 mol)).

• Step (A4): Phenylamination of the surface of hydrophobic spherical silica particles step Put 200 g of the hydrophobic spherical silica particle ketone solvent dispersion (silicon dioxide content 30.4 g, 0.51 mol) obtained in the above step (A3) into a 0.5 Then, 1.52 g of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane (0.007 mol, 5% by mass (relative to the mass of silicon dioxide)). This was heated to 100° C., and allowed to react for 3 hours. Analysis by gas chromatography of the reaction liquid after 3 hours of reaction revealed that the peak of the reaction liquid was 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): surface treatment step again with monofunctional silane compound Further, 16.1 g (0.10 mol) of hexamethyldisilazane was added from the dropping funnel to the phenylaminated spherical silica particle dispersion obtained in the above step (A4), and the It was reacted for 3 hours under the reaction temperature conditions, and then the silylation of the surface of the phenylaminated spherical silica particles was carried out. Thereafter, the dispersion medium was distilled off under reduced pressure to obtain 33 g of phenylaminated hydrophobic spherical silica particles.

[Comparative example 1] Except changing 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane in step (A4) of Example 1 to 1.8 g of N-phenyl-3 -Aminopropyltrimethoxysilane (0.007 mol, 5% by mass (relative to the mass of silicon dioxide)) (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-573), in the same manner as in Example 1 The same method as steps (A1)~(A4) was carried out for the synthesis of spherical silica particles. In step (A4), after reacting at 100°C for 3 hours, when performing gas chromatography analysis of the reaction solution, it was observed that N-phenyl-3-aminopropyltrimethoxysilane remained ( 13%). Thereafter, another surface treatment step was performed in the same manner as in step (A5) of Example 1, and finally, the dispersion medium was distilled off under reduced pressure to obtain 32 g of phenylaminated hydrophobic spherical silica particles .

[Comparative example 2] Except changing 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane in step (A4) of Example 1 to 1.2 g of 3-aminopropyl In addition to trimethoxysilane (0.007 mol, 5% by mass (relative to the mass of silica)) (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-903), the same step as in Example 1 (A1) ~(A4) The same method was used to synthesize spherical silica particles. In the step (A4), after reacting at 100° C. for 3 hours, when the reaction solution was analyzed by gas chromatography, it was confirmed that the peak of 3-aminopropyltrimethoxysilane disappeared. Thereafter, another surface treatment step was performed in the same manner as step (A5) of Example 1, and finally, the dispersion medium was distilled off under reduced pressure to obtain 33 g of aminated hydrophobic spherical silica particles.

[Table 1]

Manufacture of toner using the silica particles synthesized in the above Examples and Comparative Examples agent, and the measurement of the toner charge amount was performed, and the evaluation of image characteristics and image flow (fogging property) was performed. [Toner Charge Amount] Weighed 1 g of model toner with an average particle diameter of 8.2 μm obtained by pulverizing and classifying styrene/acrylic resin, 19 g of standard carrier P-01 (distributed by the Graphic Society of Japan), and 0.01 g of The positively charged hydrophobic spherical silica particles produced in the above-mentioned Examples and Comparative Examples. The sample prepared in this way was adjusted in humidity and mixed according to the standard of the Japan Graphic Society for the determination of the charge amount of the toner (Journal of the Japan Graphic Society, 37, 461 (1998)), and the change of the mixing was measured. The amount of toner charge over time. It should be noted that a paint conditioner (manufactured by Toyo Seiki) was used for mixing, and an air blowing type charge measuring device (manufactured by Toshiba Chemical, trade name: TB203) was used for measuring the toner charge amount. Humidity adjustment and measurement are carried out under the conditions of temperature 23±3°C and humidity 55±10%. These measurement results are shown in Table 2.

In addition, melting with a twin-screw extruder, Styrene/acrylic resin, magnetic powder, charge control agent, and wax were kneaded. After cooling, this was pulverized and classified to obtain toner particles with an average particle diameter of 8 μm. Toner composition 100 parts by mass of styrene/acrylic resin Magnetic powder (BL-200; manufactured by Titanium Industry Co., Ltd.) 75 parts by mass Charge control agent (TP-415; manufactured by Hodogaya Chemical Co., Ltd.) 4 parts by mass Wax (Viscol TS-200; manufactured by Sanyo Chemical Industry Co., Ltd.) 4 parts by mass In addition, the particle size distribution of the obtained toner particles was measured, and it was confirmed that 80% by weight or more of the whole was distributed within a particle size range of 5 to 13 μm. 0.5 parts by mass of the aforementioned positively charged hydrophobic spherical silica particles (Examples 1 to 5, Comparative Examples 1 to 2) were externally added to 100 parts by mass of the toner to manufacture a positively charged toner. Furthermore, image characteristics and image flow (fogging) of the positively charged toner were evaluated using a page printer (FS-3750) manufactured by Kyocera. It should be noted that 2% of the printed original was used as a durable printing pattern for printing. The results are shown in Table 3.

[Image Properties] Using the obtained positively charged toner, 200,000 sheets were actually printed with a page printer (FS-3750) manufactured by Kyocera Corporation, and the initial image characteristics and image characteristics after printing were evaluated according to the following criteria And image characteristics under high temperature and high humidity conditions were evaluated. Initial image characteristics (represented as "initial" in Table 3) The image evaluation pattern was printed under a normal environment (20°C, 65%RH) as an initial image, and measured using a McBeth reflection densitometer. The solid image density of the pattern was evaluated as an image, and it was evaluated. In addition, under normal environment (20°C, 65%RH) conditions, the image characteristics after printing 200,000 sheets were measured in the same manner as the initial image characteristics, and the image characteristics after printing (in Table 3, denoted as "200,000 sheets") for evaluation. Furthermore, image evaluation patterns were printed under high temperature and high humidity (33°C, 85%RH) conditions, and the image characteristics were measured in the same manner as the initial image characteristics, and the Image characteristics (expressed as "high temperature and high humidity" in Table 3) were evaluated. evaluation standard ⊚: The image density is a value of 1.35 or more. ◯: The image density is a value of 1.3 or more and less than 1.35. Δ: The image density is a value of 1.2 or more and less than 1.3. ×: The image density is a value smaller than 1.2.

[Fogging] Using the obtained positively charged toner, 200,000 sheets were actually printed on a page printer (FS-3750) manufactured by Kyocera Corporation in the same manner as in the evaluation of image characteristics, and the initial fogging property was evaluated according to the following criteria , fogging after printing, and fogging under high temperature and high humidity conditions (background fogging) were evaluated. evaluation standard ◯: Fogging is not generated at all. Δ: Slight fogging occurs. ×: Fogging is clearly generated.

[Table 2]

[table 3]

As can be seen from the above results, by using the positively charged hydrophobic spherical silica of the present invention The particles are capable of imparting desired polarity and amount of positive charge to the toner, and stably maintaining the desired polarity and amount of positive charge for a long period of time.

[Symbol Description] none.

none.

Claims (7)

A positively charged hydrophobic spherical silica particle, characterized in that the median diameter (D50) of the primary particles in the volume standard particle size distribution is 5-250nm, the ratio of D90/D10 is 3 or less, and the average circle The degree of shape is 0.8~1, and on the surface of the positively charged hydrophobic spherical silica particles, an organosilicon compound represented by the following general formula (I) is bonded:

In the general formula (I), R ¹ and R ² are independently a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and n is 0 or 1. The positively charged hydrophobic spherical silica particles according to claim 1, wherein a silazane compound represented by the following general formula (III) and a monofunctional silane compound represented by the following general formula (IV) are further used or mixtures thereof have undergone surface treatment: R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or In the unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group. A method for manufacturing positively charged hydrophobic spherical silica particles, which manufactures positively charged hydrophobic spherical silica particles as described in Claim 2, characterized in that it comprises the following steps (A2) to (A4) ; Step (A2): With respect to the Si atom of the hydrophilic spherical silica particle dispersion of 1 mole, the silazane compound represented by the following general formula (III) of 0.01 ~ 0.1 mole, the following general formula The monofunctional silane compound represented by (IV) or its mixture is added to the hydrophilic spherical silica particle dispersion, and then the R ⁴ ₃ SiO _1/2 unit is introduced on the surface of the hydrophilic spherical silica particle , so as to obtain a dispersion of hydrophobic spherical silica particles, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In general formula (III) and general formula (IV), R ⁴ represents the same or different A substituted or unsubstituted monovalent hydrocarbon group with 1 to 6 carbon atoms, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group; step (A3): will be obtained from step (A2) The dispersion medium of the described hydrophobic spherical silicon dioxide particle dispersion is replaced by a ketone solvent, and then the ketone solvent dispersion of the hydrophobic spherical silicon dioxide particle is obtained; step (A4): the following general formula (I) The organosilicon compound indicated is added to the ketone solvent dispersion of the hydrophobic spherical silica particles obtained in the step (A3), and the silanol groups on the surface of the hydrophobic spherical silica particles group undergoes phenylamination,

In the general formula (I), R ¹ and R ² independently represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and n is 0 or 1. The method for producing positively charged hydrophobic spherical silica particles according to claim 3, wherein the hydrophilic spherical silica particle dispersion is produced through the following step (A1), step (A1): by In the presence of an alkaline substance, hydrolyze and condense a tetrafunctional silane compound represented by the following general formula (II), its partially hydrolyzed condensate, or a mixture thereof in a mixed solution containing a hydrophilic solvent and water, and then obtain the obtained The above-mentioned hydrophilic spherical silica particle dispersion, Si(OR ³ ) ₄ (II) In the general formula (II), R ³ represents the same or different monovalent hydrocarbon groups with 1 to 6 carbon atoms. The method for producing positively charged hydrophobic spherical silica particles as described in claim 3, further comprising the following step (A5); step (A5): relative to 1 mole of phenyl aminated spherical silica For the Si atom of the silicon particles, 0.01 to 0.3 moles of a silazane compound represented by the following general formula (III), a monofunctional silane compound represented by the following general formula (IV) or a mixture thereof are added in the step ( In the dispersion of phenylaminated spherical silica particles obtained in A4), and reacting with the silanol groups remaining on the surface of the phenylaminated spherical silica particles, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In the general formula (III) and the general formula (IV), R ⁴ represents the same or different substituted or unsubstituted monovalent Hydrocarbon group, in general formula (IV), X represents a hydroxyl group or a hydrolyzable group. The method for producing positively charged hydrophobic spherical silica particles as described in claim 4, further comprising the following step (A5), step (A5): relative to 1 mole of phenyl aminated spherical silica For the Si atom of the silicon particles, 0.01 to 0.3 moles of a silazane compound represented by the following general formula (III), a monofunctional silane compound represented by the following general formula (IV) or a mixture thereof are added in the step ( In the dispersion of phenylaminated spherical silica particles obtained in A4), and reacting with the silanol groups remaining on the surface of the phenylaminated spherical silica particles, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or unsubstituted monovalent 1 to 6 carbon atoms Hydrocarbon group, in general formula (IV), X represents a hydroxyl group or a hydrolyzable group. A positively charged toner composition, characterized by comprising toner and positively charged hydrophobic spherical silica particles as described in claim 1 or 2.