TW202009615A - Positive charge type hydrophobic spherical silica particles, method for producing same and positively charged toner composition using same - Google Patents

Abstract

The present invention provides: silica particles for external toner additives, which are capable of imparting a toner with a desired positive electrostatic charge, and which enable the toner to stably maintain the positive electrostatic charge for a long period of time; and a toner composition which contains the silica particles. Positive charge type hydrophobic spherical silica particles which have a median diameter (D50) of primary particles of 5-250 nm in the volume-based particle size distribution, a D90/D10 ratio of 3 or less and an average circularity of 0.8-1, and to the surfaces of which an organic silicon compound represented by formula (I) is bonded. (In the formula, each of R1 and R2 independently represents a hydrogen atom or a linear, branched or cyclic alkyl group having 1-10 carbon atoms; and n represents 0 or 1.).

Description

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

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

In the electrophotographic development method, by visualizing the electrostatic latent image or by reversal development Visualize electrostatic latent images to obtain high-quality images. The 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 , Classification, and manufacturing toner particles. In addition, in order to impart fluidity to the toner particles while improving 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 usually highly hydrophilic, and may be affected by the surrounding environmental conditions (humidity) to change the fluidity or charge rise of the toner.

Therefore, in order to reduce the impact on these environmental conditions, A method of introducing the charged polar groups onto the surface of the inorganic fine powder while managing the surface of the inorganic fine powder. Among these methods, in particular, Patent Document 1 (Japanese Patent Laid-Open No. 52-135739) and Patent Document 2 (Japanese Patent Laid-Open No. 56-123550) disclose surface treatment with an aminosilane coupling agent and the like A method of using metal oxides such as silicon dioxide fine powder as an external additive for positively charged toners. According to this silane treatment method, a developer exhibiting strong positive charge can be obtained through the terminal amine group of the amine silane coupling agent.

In addition, Patent Document 3 (Japanese Patent Laid-Open No. 58-216252) discloses A method for surface-treating hydrophobic silica 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 for treating a fine powder of silicon dioxide with a predetermined amount of a nitrogen-containing silane coupling agent and a silicon oil having a nitrogen atom, and using it as a developer The method of using external additives. According to these methods, a developer exhibiting strong positive charge can be obtained by the action of the positive charge control agent.

In addition, for example, in Patent Document 6 (Japanese Patent Laid-Open No. 2-66564), the A method has been developed to use inorganic particles in which polar groups of both negatively charged polar groups and positively charged polar groups are bonded to the surface as external additives for nonmagnetic single-component developing toners. According to this method, a non-magnetic single-component developing toner excellent in charge level improvement, charge rise performance, and fluidity, respectively, can be obtained.

In addition, Patent Document 7 (Japanese Patent Laid-Open No. 11-160907) discloses An invention. The content is that in order to obtain charge rise, improve durability and environmental stability, it uses a dry silicon dioxide fine powder having a positively charged polar group and a hydrophobic group and a silicone oil using a positively charged polar group for hydrophobicity The method of chemical treatment of wet silica fine powder is effective. In addition, Patent Document 8 (Japanese Patent Laid-Open No. 11-143111) discloses an invention. Its content is that in order to obtain charge rise, improve 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 The method of agglomerated wet silica fine powder is effective. In addition, Patent Document 9 (Japanese Patent Laid-Open No. 2007-108801) discloses an invention. Its content is that in order to obtain long-term effective good image density and fogging resistance even when printing with a low printing rate has been implemented, as an external additive, it contains a positively charged polar group and a hydrophobic group The positive charge toner of the dry silicon dioxide fine powder and the wet silicon dioxide fine powder surface-treated with a quaternary ammonium salt type silane compound having a fluorine-containing negatively charged polar group is effective. [Prior Art Literature]

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

[Problems to be solved by the invention] It is known from the above-mentioned literature that although external additives for positively charged toners are usually treated with amine-based silane coupling agents such as amine-trialkoxysilanes, these positively-charged hydrophobic spherical silica particles are When used as a toner external additive, there is a problem that the long-term contact with the carrier will cause the amine silane component to peel off from the surface of the silica, showing the original negative chargeability of the silica, and further reducing the positive chargeability. . The reason is presumed to be that before the silanol group on the surface of the silica reacts with the alkoxy group of the amine group such as amine trialkoxysilane, the amine group of the amine group reacts with the silica 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 of the aminosilanes only adhere to the surface of silicon dioxide. Therefore, an object of the present invention is to provide silica particles for toner external additives capable of imparting the required positive charge polarity to the toner and being stable for a long period of time, that is, excellent in positive charge retention, and containing The toner composition of the silica particles.

[Technical means to solve problems] In view of the above problems, the present inventors have conducted in-depth studies 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 is to provide 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 silica particles.

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, in which the median diameter (D50) of the primary particles in the volume-standard particle size distribution is 5 to 250 nm, the ratio of D90/D10 is 3 or less, and the average The roundness is 0.8~1, and an organic silicon compound represented by the following general formula (I) is bonded to 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], which further utilize a silazane compound represented by the following general formula (III) and a monofunctional property represented by the following general formula (IV) The surface treatment of the silane compound or its mixture, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In the general formula (III), general formula (IV), R ⁴ represents the same or different The 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 manufacturing positively charged hydrophobic spherical silica particles, wherein the positively charged hydrophobic spherical silica particles are positively charged hydrophobic spherical silica according to [1] or [2] For particles, the above manufacturing method includes the following steps (A2) to (A4), and step (A2): relative to 1 atom of the Si atom of the hydrophilic spherical silica particle dispersion, the following is 0.01 to 0.1 mole The silazane compound represented by the above 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 to obtain 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 the general formula (IV), R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms. In the general formula (IV), X represents hydroxyl group or hydrolysis Groups, step (A3): replacing the dispersion medium of the hydrophobic spherical silica particle dispersion obtained in step (A2) with a ketone solvent, and then obtaining the ketone solvent dispersion of the hydrophobic spherical silica particles Body, step (A4): the organosilicon compound represented by the following general formula (I) is added to the ketone solvent dispersion of the hydrophobic spherical silica particles obtained in step (A3), and the Silanol groups on the surface of the hydrophobic spherical silica particles undergo phenyl amination, [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): The tetrafunctional silane compound represented by the following general formula (II), its partially hydrolyzed condensate or a mixture thereof is hydrolyzed and condensed in the presence of an alkaline substance in a mixed solution containing a hydrophilic solvent and water Hydrophilic spherical silica particle dispersion, Si(OR ³ ) ₄ (II) In the general formula (II), R ^{3 is} represented by 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): relative to 1 mole The Si atoms of the phenylaminated spherical silica particles are 0.01 to 0.3 moles of silazane compound represented by the following general formula (III), monofunctional silane compound represented by the following general formula (IV) or The mixture thereof is added to the phenylaminated spherical silica particle dispersion obtained in step (A4), and it is allowed to react with the silanol group remaining on the surface of the phenylaminated spherical silica particles Group reaction, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In the general formula (III), general formula (IV), R ⁴ represents the same or different substituted or unsubstituted carbon In the monovalent hydrocarbon group having 1 to 6 atoms, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group.

[6] A positively-charged toner composition, which comprises according to [1] or [2] Of positively charged hydrophobic spherical silica particles.

[Effect of invention] The positively charged hydrophobic spherical silica particles of the present invention have a rapid charge rise and excellent positive charge storage properties over time. In addition, the toner composition containing the positively charged hydrophobic spherical silica particles of the present invention is excellent in fluidity and printing characteristics, and these characteristics are also less affected by changes in 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 to 250 nm, and the D90/D10 ratio is 3 or less, with an average circularity of 0.8 to 1, and an organic silicon compound represented by the following general formula (I) 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 having 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 having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or a cyclic ring having 3 to 10 carbon atoms Of alkyl. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, and octyl. And decyl. Among them, hydrogen atoms and methyl groups with small steric hindrance do not hinder the reaction with the surface of silicon dioxide, so it is preferable.

Specific examples of the organosilicon compound represented by the 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 volume standard particle The median diameter of the primary particles in the degree distribution (D50: the diameter from the small side of the particle to 50% of the accumulated particle diameter) is 5 to 250 nm, preferably 10 to 200 nm. If D50 is less than 5nm, the particles are aggregated seriously, which may cause the whole to gel or stick to the inside of the production equipment, which can not be removed smoothly; in addition, if 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 by In the standard particle size distribution, when the particle diameter from the small particle size to the cumulative 10% is taken as D10, and the particle diameter from the small particle size to the cumulative 90% is taken as D90, the ratio of D90/D10 Since it is 3 or less, the particle size distribution range is narrow. Such particles having a narrow particle size distribution have the advantage of easy control of fluidity and are therefore preferred. The D90/D10 ratio is preferably 2.9 or less. In addition, in this invention, the volume standard particle size distribution is measured by the dynamic light scattering method using a laser beam.

In addition, in the present invention, the circularity means "having the same "Circumference of area"/"Circumference of particle projection image". Specifically, it is calculated based on the shape obtained by an electron microscope (magnification: 100,000 times), and the circularity of the averaged 10 silica particles is regarded as the "average circularity". The positively charged hydrophobic spherical silica particles of the present invention have an average circularity of 0.8 to 1, preferably 0.92 to 1. In addition, the "spherical shape" referred to in the present invention is not only a true ball but also a slightly deformed ball. It should be noted that the shape of these particles is 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 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 group, 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 carbon atom having 1 to 4 carbon atoms, and preferably a monovalent hydrocarbon group having 1 to 2 carbon atoms. Examples of the monovalent hydrocarbon group represented by R ⁴ include, for example, alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl, preferably methyl, ethyl, and propyl, and methyl and Ethyl is preferred. In addition, some or all of the hydrogen atoms in these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, preferably with fluorine atoms.

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

As the silazane compound represented by the above general formula (III), for example, six Methyldisilazane, hexaethyldisilazane, etc., preferably hexamethyldisilazane. Examples of the monofunctional silane compound represented by the general formula (IV) include, for example, monosilanol compounds such as trimethylsilanol and triethylsilanol; trimethylchlorosilane and triethylchlorosilane Monochlorosilanes; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; Monomethyloxysilane such as trimethylacetoxysilane, etc., preferably trimethylsilanol, trimethylmethoxysilane and trimethylsilyldiethylamine, trimethylsilanol and trimethyl Methoxysilane is preferred.

Evaluation of the hydrophobicity of the positively charged hydrophobic spherical silica particles of the present invention The valence method is not particularly limited. For example, the methanol wettability method (MW method) may be used to calculate the hydrophobicity (methanol wettability). The hydrophobicity of the positively charged hydrophobic spherical silica particles of the present invention when measured in the following procedure is preferably 60% or more, and more preferably 65% or more. 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, a good charge can be obtained stability.

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

Hereinafter, the method for producing the 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 from steps (A2) to (A4). In addition, the hydrophilic spherical silica particle dispersion as the raw material of step (A2) can be obtained by, for example, step (A1). Step (A1): Synthetic steps to obtain a hydrophilic spherical silica particle dispersion Step (A2): Surface treatment step through monofunctional silane compound Step (A3): Dispersing medium replaces the step Step (A4): Step of anilylation of the surface of the hydrophobic spherical silica particles Hereinafter, each step will be described in order.

Step (A1): a synthetic step to obtain a hydrophilic spherical silica particle dispersion. 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 and its partial Synthetic step of hydrolyzing and condensing a substance or its mixture 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 is} represented by the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms.)

In the above general formula (II), R ³ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, and a monovalent hydrocarbon group having 1 to 2 carbon atoms is preferred good. Examples of the monovalent hydrocarbon group represented by R ³ include methyl, ethyl, propyl, butyl, and phenyl groups, preferably methyl, ethyl, propyl, and butyl groups, and methyl and ethyl groups. The base is better.

Examples of the tetrafunctional silane compound represented by the general formula (II) include, for example, Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrabutoxysilane and tetraphenoxysilane, etc., with tetramethoxysilane and tetraethoxysilane , Tetrapropoxysilane and Tetrabutoxysilane are preferred, and Tetramethoxysilane and Tetraethoxysilane are preferred. In addition, examples of the hydrolyzed condensate of the tetrafunctional silane compound represented by the general formula (II) include methyl silicate and ethyl silicate.

Examples of the alkaline substance include ammonia, dimethylamine, and diethylamine. Ethylamine is preferred, and ammonia is preferred. These alkaline substances can be dissolved and used in water in prescribed amounts.

Examples of the hydrophilic solvent include methanol, ethanol, 1-propanol, and 2-propanol. And alcohols such as third butanol; ethers such as tetrahydrofuran and dioxane; glycols such as diethylene glycol and dipropylene glycol.

With respect to the tetrafunctional silane compound represented by the general formula (II) and/or its partial hydrolysis The total amount of hydrocarbyloxy groups of the condensate is 1 mole. The amount of water used in this step is preferably 0.5 to 5 moles, preferably 0.6 to 2 moles, and more preferably 0.7 to 1 moles. . From the viewpoint of the affinity of the hydrophobized spherical silica particles with the mixed solvent and the ease of manufacturing, the ratio of the hydrophilic solvent to water is calculated as a mass ratio, preferably 0.5 to 10, and 3 to 9 Preferably, 5~8 is better. The amount of the alkaline substance is preferably 0.01 to 2 mol, preferably 0.02 to the total of 1 mol of the hydrocarbyloxy group of the tetrafunctional silane compound represented by the general formula (II) and/or its partially hydrolyzed condensate 0.5 mole is better, and 0.04~0.12 mole is better.

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

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

In addition, as a substitute for the above step (A1) and used in the (A2) step of the hydrophilic ball A commercially available product may be used as the dispersion of shaped silica particles. As a commercially available product, a hydrophilic spherical silica particle dispersion in which hydrophilic spherical silica particles have been dispersed in a hydrophilic solvent such as the above alcohols can be used. In the case of using a commercially available product, when used in the step (A2), a hydrophilic solvent is added or distilled in such a way as to form an appropriate silica particle concentration, and then the commercially available hydrophilic spherical silica The particle dispersion is used after being diluted or concentrated. The concentration of silicon dioxide particles in this case is the same as the concentration of silicon dioxide particles in the hydrophilic spherical silicon dioxide particle dispersion obtained in the above step (A1), preferably 2 to 20% by mass.

Step (A2): Surface treatment step by a monofunctional silane compound This step is a hydrophilic spherical dioxide obtained in step (A1) with respect to 1 mole of Si atoms of the hydrophilic spherical silica particle dispersion To the silicon particle dispersion, 0.01 to 0.1 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, and then R43SiO1/2 The step of introducing at least a part of the surface of the hydrophilic spherical silica particles to obtain a dispersion of hydrophobic spherical silica particles. R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) (In the general formula (III) and general formula (IV), R ⁴ represents the same or different substituted or unsubstituted carbon atoms 1~ 6 is a monovalent hydrocarbon group, 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 having 1 to 4 carbon atoms, and preferably a carbon atom having 1 to 2 carbon atoms. Examples of the monovalent hydrocarbon group represented by R ⁴ include alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl groups, preferably methyl, ethyl, and propyl groups, and 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 with fluorine atoms.

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

As the silazane compound represented by the above general formula (III), hexamethyl di Silazane, hexaethyldisilazane, etc., preferably hexamethyldisilazane. Examples of the monofunctional silane compound represented by the above general formula (IV) include monosilanol compounds such as trimethylsilanol and triethylsilanol; monomethylols such as trimethylchlorosilane and triethylchlorosilane Chlorosilane; Monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; Monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; Trimethyl Monoethyloxysilane such as ethyl ethoxy silane and the like, preferably trimethylsilanol, trimethylmethoxysilane and trimethylsilyldiethylamine, trimethylsilanol and trimethylmethyl Oxysilane is preferred.

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

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 a mixture thereof is added to the hydrophilic spherical silica particle dispersion, and the surface treatment reaction is performed by the monofunctional silane compound under the following reaction conditions. The reaction conditions of the surface treatment in this step (A2) are preferably a reaction temperature of 40-60°C and a reaction time of 1-10 hours, preferably a reaction temperature of 50-60°C and a reaction time of 2-8 hours.

Step (A3): Dispersing medium replaces the step In this step, the dispersion medium composed of water, a hydrophilic organic solvent, and volatile by-products such as alcohol produced by condensation in the hydrophobic spherical silica particle dispersion obtained in step (A2) is replaced with ketones Solvent steps.

Specific examples of ketone solvents include methyl ethyl ketone, methyl isobutyl ketone, and ethyl Acetylacetone, etc., preferably methyl isobutyl ketone.

From the viewpoint of suppressing the aggregation of silica particles, and the aminosilane in the next step From the viewpoint of the concentration of the reaction system during the treatment, the amount of the ketone solvent added to the hydrophobic spherical silica particles obtained in step (A2) is calculated by weight ratio, and the amount used is 0.5 to 5 times It is better to use 1 to 2 times the amount.

As a hydrophilic organic solvent and water in the dispersion of hydrophobic spherical silica particles The method of replacing volatile by-products such as alcohol generated by condensation with a ketone-based solvent can be exemplified by methods such as concentration (atmospheric pressure or reduced pressure) and ultrafiltration using a filter. It is preferable to add the hydrophilic organic solvent and the ketone solvent having a boiling point higher than water contained in the hydrophobic spherical silica particle dispersion obtained in step (A2) to the hydrophobic spherical dioxide obtained in step (A2) A method of concentrating silicon particles in a dispersion.

（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): Step of anilylation of the surface of the hydrophobic spherical silica particles This step is to add the organosilicon compound represented by the following general formula (I) to the hydrophobicity obtained in step (A3) In the ketone solvent dispersion of the spherical silica particles, at least a part of the silanol groups on the surface of the hydrophobic spherical silica particles is subjected to an anilation step. [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 having 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 having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or a carbon atom having 3 to 10 carbon atoms Cyclic alkyl. Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, and octyl. And decyl. Among them, hydrogen atoms and methyl groups with small steric hindrance do not hinder the reaction with the surface of silicon dioxide, so it is preferable.

Specific examples of the organosilicon compound represented by the 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.

Treatment of hydrophobic spherical by using the organosilicon compound represented by the above general formula (I) On the surface of silicon dioxide, positively charged hydrophobic spherical silicon dioxide particles can be obtained.

The surface treatment step is preferably to convert the organosilicon compound represented by the above general formula (I) The method is to add to the mixed solution in which hydrophobic spherical silica particles have been dispersed in a ketone solvent for treatment. The organosilicon compound represented by the above general formula (I) may be used directly, or the organosilicon compound may be diluted and added in the ketone solvent.

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

After adding the organosilicon compound represented by the above general formula (I), the reaction temperature The reaction is preferably carried out under the conditions of a temperature of 20 to 120°C, a reaction time of 1 to 8 hours, and preferably carried out at a reaction temperature of 20 to 100°C and a reaction time of 1 to 6 hours.

The production of the positively charged hydrophobic spherical silica particles of the present invention is preferably produced by the following step (A5). Step (A5): The silazane compound represented by the following general formula (III) is represented by the following formula at a ratio of 0.01 to 0.3 moles relative to 1 mole of Si atoms of the phenylaminated spherical silica particles. 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 step (A4), and allowed to remain with the 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 group having 1 to 6 carbon atoms. In the general formula (IV), X represents a hydroxyl group or a hydrolyzed group).

The compound represented by the above general formulas (III) and (IV) in step (A5) is The same as the compound described in the above step (A2). In this step, the silanol groups remaining on the surface of the silicon dioxide particles after the above step (A4) are further triorganosilated, and the obtained silicon dioxide particles are highly hydrophobicized and the fluidity is improved, thereby enabling Inhibits the formation of silicon dioxide anions caused by protons released from residual silanol groups.

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

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

After the reaction, by adapting from the dispersion of positively charged hydrophobic spherical silica particles Locally removing volatile by-products such as dispersion media and alcohol can obtain positively charged hydrophobic spherical silica particles.

Hereinafter, the positively-charged toner composition of the present invention will be described in detail. The positively charged toner composition of the present invention contains the positively charged hydrophobic spherical silica particles of the present invention described above as the toner external additive. When the positively charged hydrophobic spherical silica particles are used as a toner external additive, the amount of preparation is usually 0.1 to 3 parts by mass relative to 100 parts by mass of the toner, preferably 0.3 to 2 parts. Quality parts are preferred. Within such a range, it is possible to impart stable positive chargeability 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 pass the usual Manufacturing method. For example, a method of mixing the positively charged hydrophobic spherical silica particles of the present invention in the toner particles obtained by melt-blending, pulverizing, and classifying the binder resin, colorant, and other additives can be cited. [Example]

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

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

[Particle shape] Using an electron microscope (manufactured by Hitachi, Model S-4700, magnification: 100,000 times), the silica particles were observed and the shape of the particles was confirmed. Use the calculation formula of "the circumference of a circle with an area equal to the area of the particle"/"the circumference of the particle projection image" to obtain the roundness when the particles are projected in two dimensions. Among them, the circle of 10 silica particles The average value of the shape is regarded as the average circularity.

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

According to the mass spectrum, ¹ H-NMR spectrum (dichloroform solvent) and IR spectrum of the obtained fraction, the compound obtained was confirmed to be 2,2-dimethoxy-1-phenyl-1-nitrogen Hetero-2-Silacyclopentane.

[Example 1] • Step (A1): Synthetic steps to obtain a hydrophilic spherical silica particle dispersion 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 while stirring, 646.5 g (4.25 mol) of tetramethoxysilane and 160.9 g of 5.4% ammonia water were added dropwise, and added dropwise for 3 hours. After the dropwise addition, the mixture was further stirred and hydrolyzed for 0.5 hours to obtain a dispersion of 1662 g of hydrophilic spherical silica particles.

• Step (A2): Surface treatment step with monofunctional silane compound 600g of the hydrophilic spherical silica particle dispersion (silica content 15% by mass, 90g (1.5 mole)) obtained in the above step (A1) was added to 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, and then the silylation of the surface of the hydrophilic spherical silica particles was performed.

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

• Step (A4): Phenyl amination of the surface of hydrophobic spherical silica particles step 200g of the hydrophobic spherical silica particle ketone solvent dispersion (silica content 30.4g, 0.51 mole) obtained in the above step (A3) was put into 0.5 equipped with a stirrer, dropping funnel and thermometer In a glass reactor, 1.52 g of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane (0.007 mol, 5 mass% (relative to the mass of silicon dioxide)). It was heated at 100°C and allowed to react for 3 hours. By gas chromatography analysis of the reaction liquid after 3 hours of reaction, the reaction liquid was confirmed to be the peak of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): The surface treatment step is performed again with a 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 at 100°C The reaction temperature was allowed to react for 3 hours, 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, and 32 g of phenylaminated hydrophobic spherical silica particles were obtained.

[Example 2] In addition to changing the amount of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane in step (A4) of Example 1 to 3.1 g (0.014 mol, Except 10% by mass (relative to the mass of silica), Example 2 was carried out 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 hydrophilic spherical silica particle dispersion 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 with stirring, 1163.7g (7.66 moles) of tetramethoxysilane and 418.1g of 5.4% ammonia were added dropwise, and the former was added dropwise for 6 hours, and the latter was added dropwise by 4 hour. After the end of the dropwise addition, hydrolysis was continued by further stirring for 0.5 hours, thereby obtaining a dispersion of 2295 g of hydrophilic spherical silica particles.

• Step (A2): Surface treatment step with monofunctional silane compound 600g of the dispersion obtained in the above step (A1) (silica content 20% by mass, 120g (2mol)) was added to a 5-liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer At 25 ℃, add 9.7g (0.06 mol) of hexamethyldisilazane and mix. The solution was heated to 60°C and allowed to react for 3 hours, and then the silylation of the surface of the hydrophilic spherical silica particles was carried out.

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

• Step (A4): Phenyl amination of the surface of hydrophobic spherical silica particles step 200 g of the hydrophobic spherical silica particle ketone solvent dispersion (silica content 32 g, 0.53 mole) obtained in the above step (A3) was put into 0.5 liter equipped with a stirrer, dropping funnel and 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°C and allowed to react for 3 hours. By gas chromatography analysis of the reaction liquid after 3 hours of reaction, the reaction liquid was confirmed to be the peak of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): The surface treatment step is performed again with a monofunctional silane compound Further, 12.9 g (0.08 mol) of hexamethyldisilazane was added to the phenylaminated spherical silica particle dispersion obtained in the above step (A4) from the dropping funnel at 100°C The reaction temperature was allowed to react for 3 hours, and then the surface of the phenylaminated spherical silica particles was silanized. 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 after the completion of step (A4), the dispersion medium was directly distilled off under reduced pressure, thereby obtaining 29 g of phenylaminated hydrophobic spherical silica particles.

[Example 5] A commercially available hydrophilic spherical silica particle dispersion (manufactured by Nissan Chemical Industry Co., Ltd., IPA-ST-L, particle size 45 nm, 30% by mass isopropyl alcohol dispersion) was used instead of step (A1).

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

• Step (A3): Dispersing medium replaces the step 1200 g of methyl isobutyl ketone was added to the reaction vessel after the above step (A2). The ester adaptor and the cooling tube were installed on a glass reaction vessel, and heated to 80~110°C and used for 5 hours to remove 1220g of isopropanol through concentration, thereby obtaining 575g of hydrophobic spherical silica particle ketone Solvent-like dispersion (silica content is 15.6% by mass, 90g (1.5mol)).

• Step (A4): Phenyl amination of the surface of hydrophobic spherical silica particles step 200g of the hydrophobic spherical silica particle ketone solvent dispersion (silica content 30.4g, 0.51 mole) obtained in the above step (A3) was put into 0.5 equipped with a stirrer, dropping funnel and thermometer In a glass reactor, 1.52 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°C and allowed to react for 3 hours. By gas chromatography analysis of the reaction liquid after 3 hours of reaction, the reaction liquid was confirmed to be the peak of 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane disappear.

• Step (A5): The surface treatment step is performed again with a 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 at 100°C The reaction temperature was allowed to react for 3 hours, 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] In addition to 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), as in Example 1. In steps (A1) to (A4), spherical silica particles were synthesized in the same way. In step (A4), after reacting at 100°C for 3 hours, when performing gas chromatography analysis of the reaction liquid, the presence of N-phenyl-3-aminopropyltrimethoxysilane ( 13%). Thereafter, the surface treatment step was again performed in the same manner as the 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] In addition to changing 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane in step (A4) of Example 1 to 1.2 g of 3-aminopropyl Trimethoxysilane (0.007 mol, 5 mass% (relative to the mass of silicon dioxide)) (manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM-903), as in Example 1 (A1) ~ (A4) Synthesized spherical silica particles in the same way. In step (A4), after the reaction was carried out at 100° C. for 3 hours, when the gas chromatography analysis of the reaction liquid was performed, it was confirmed that the peak of 3-aminopropyltrimethoxysilane disappeared. Thereafter, the surface treatment step was again performed in the same manner as the 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]

Using the silica particles synthesized in the above examples and comparative examples to produce toning In addition, the toner charge was measured, and the image characteristics and image flow (fogging) were evaluated. [Toner charge amount] Weighed 1g of model toner with an average particle size of 8.2μm obtained by crushing and classifying styrene/acrylic resin, 19g of standard carrier P-01 (distributed by the Japan Society of Imaging) and 0.01g respectively Of the positively charged hydrophobic spherical silica particles produced in the above examples and comparative examples. The samples prepared in this way were subjected to humidity adjustment and mixing in accordance with the standard of charge measurement of toners of the Japan Society of Imaging Society (Journal of the Japan Society of Imaging, 37, 461 (1998)), and the change of mixing was measured. The amount of toner charge at time. In addition, when mixing, a paint regulator (manufactured by Toyo Seiki) was used; when measuring the toner charge amount, a blower type charge amount measuring device (manufactured by Toshiba Chemicals, trade name: TB203) was used. Humidity adjustment and measurement are carried out under the conditions of temperature 23±3℃ and humidity 55±10%. The measurement results are shown in Table 2.

In addition, the twin-screw extruder was used to melt, Styrene/acrylic resin, magnetic powder, charge control agent and wax are mixed. After cooling it, it was pulverized and classified to obtain toner particles having 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; made 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 entire distribution was within a particle size range of 5 to 13 μm. With respect to 100 parts by mass of the toner, 0.5 parts by mass of the above-mentioned positively charged hydrophobic spherical silica particles (Examples 1 to 5 and Comparative Examples 1 to 2) were added to produce a positively charged toner. Furthermore, using a page printer (FS-3750) manufactured by Kyocera Corporation, the image characteristics and image flow (fogging property) of the positively-charged toner were evaluated. It should be noted that 2% of the printed manuscript is used as the printing durability printing pattern. The results are shown in Table 3.

[Image characteristics] 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 the image characteristics after printing were based on the following standards And the image characteristics under high temperature and high humidity conditions were evaluated. The initial image characteristics (reported as "initial" in Table 3) were printed under the normal environment (20°C, 65%RH) and evaluated as an initial image, which was measured using a Macbeth reflection densitometer The solid image density as an image evaluation pattern was evaluated. In addition, under normal environmental conditions (20°C, 65%RH), the image characteristics after printing 200,000 sheets were measured in the same way as the initial image characteristics, and the image characteristics after printing (in the table) 3 is expressed as "200,000 sheets") for evaluation. Furthermore, under high temperature and high humidity (33°C, 85%RH), the image evaluation pattern was printed, and the image characteristics were measured in the same manner as the initial image characteristics. The image characteristics (reported 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. △: The image density is a value of 1.2 or more and less than 1.3. ×: The image density is a value less than 1.2.

[Foginess] Using the obtained positively-charged toner, as in the evaluation of image characteristics, 200,000 sheets were actually printed with a page printer (FS-3750) manufactured by Kyocera Corporation, and the initial fogging properties were in accordance with the following standards , Fogging after printing and fogging under high temperature and high humidity (background fogging) were evaluated. evaluation standard ○: No fogging was generated at all. △: Fogging occurred slightly. ×: Fogging is clearly generated.

[Table 2]

[table 3]

From the above results, it can be seen that by using the positively charged hydrophobic spherical silica of the present invention The particles can impart the desired positive charge polarity and charge amount to the toner, and can stably maintain the desired positive charge polarity and charge amount for a long time.

[Symbol Description] no.

no.

Claims (7)

A positively charged hydrophobic spherical silica particle, characterized in that the median diameter (D50) of primary particles in a volume-standard particle size distribution is 5 to 250 nm, the ratio of D90/D10 is 3 or less, and the average circle The shape degree is 0.8~1, and on the surface of the positively charged hydrophobic spherical silica particles, an organic silicon 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 a mixture of these has been surface-treated: 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 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 includes the following steps (A2) to (A4) ; Step (A2): The silazane compound represented by the following general formula (III) of 0.01 to 0.1 mol and the following general formula with respect to Si atoms of 1 mol of hydrophilic spherical silica particle dispersion The monofunctional silane compound represented by (IV) or a mixture thereof is added to the hydrophilic spherical silica particle dispersion, and R ⁴ ₃ SiO _1/2 units are further introduced on the surface of the hydrophilic spherical silica particles , To obtain a hydrophobic spherical silica particle dispersion, R ⁴ ₃ SiNHSiR ⁴ ₃ (III) R ⁴ ₃ SiX (IV) In the general formula (III), general formula (IV), R ^{4 is} expressed as the same or different The 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; Step (A3): will be obtained from step (A2) The dispersion medium of the hydrophobic spherical silica particles dispersion is replaced with a ketone solvent to obtain a ketone solvent dispersion of hydrophobic spherical silica particles; Step (A4): The following general formula (I) The organosilicon compound represented is added to the ketone solvent dispersion of the hydrophobic spherical silica particles obtained in step (A3), and the silanol group on the surface of the hydrophobic spherical silica particles The group undergoes phenyl amination,

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 particles dispersion is produced by the following step (A1), step (A1): The tetrafunctional silane compound represented by the following general formula (II), its partially hydrolyzed condensate or a mixture thereof are hydrolyzed and condensed in the presence of an alkaline substance in a mixed solution containing a hydrophilic solvent and water Said 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 of 1 to 6 carbon atoms. The method for producing positively charged hydrophobic spherical silica particles according to claim 3, further comprising the following steps (A5); Step (A5): phenylaminated spherical dioxide with respect to 1 mole For the Si atoms 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 ( A4) The phenylaminated spherical silica particles dispersion obtained in the above and react with 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 carbon number of 1 to 6 carbon atoms The hydrocarbon group, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group. The method for producing positively charged hydrophobic spherical silica particles according to claim 4, further comprising the following step (A5), step (A5): phenylaminated spherical dioxide with respect to 1 mole For the Si atoms 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 ( A4) The phenylaminated spherical silica particles dispersion obtained in the above and react with 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 carbon number of 1 to 6 carbon atoms The hydrocarbon group, in the general formula (IV), X represents a hydroxyl group or a hydrolyzable group. A positively charged toner composition, characterized in that it contains the Positively charged hydrophobic spherical silica particles.