JP2011185998A - Electrostatic image-developing toner and electric charge-controlling particle for external addition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic image-developing toner which keeps the amount of triboelectric charges, which is generated between the toner itself and a carrier, at a prescribed range to hardly cause the deterioration of an image even if it is used for a long period of time. <P>SOLUTION: Electric charge-controlling particles for external addition, which control the amount of triboelectric charges of the electrostatic image-developing toner, comprises: conveyance particles which consist of hydrophobic spherical silica microparticles having an average particle size of 20-500 nm which are obtained by subjecting the surfaces of hydrophilic spherical silica microparticles obtained by a sol-gel method to hydrophobic processing; and an electric charge-controlling agent with which the surfaces of the conveyance particles are coated. In addition, the electric charge-controlling particles for external addition have the electric charge-controlling agent of 1×10<SP>-3</SP>to 1×10<SP>-1</SP>pts.mass to the conveyance particles of 1 pts.mass, and the electric charge-controlling particles for external addition of 0.001-0.05 pts.mass is mixed with the toner of 1 pts.mass in the electrostatic image-developing toner. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrostatic image developing toner used for developing an electrostatic image in an electrophotographic method, an electrostatic recording method, and the like, and charge control particles for external addition for controlling the triboelectric charge amount of the toner.

  Conventionally, in electrophotography, charged colored particles (hereinafter referred to as toner) are brought into contact with a photoconductor surface or dielectric surface having an electrostatic latent image, and the charged toner is charged in the electrostatic latent image. Accordingly, a visible image is formed by adhering to a photoconductor surface or a dielectric surface, and this visualization operation is usually called development.

  The most commonly used pulverized toner is a thermoplastic resin binder for a toner, a pigment, a charge control agent (hereinafter referred to as CCA), a wax and the like, which are kneaded and pulverized to obtain an average particle size of 5 to 5. Obtained as colored particles classified to 10 μm.

  In addition, suspension polymerization type chemical toners that have recently started to be used frequently are prepared by dispersing droplets with an average particle diameter of 5 to 10 μm mixed and dispersed in water, and polymerizing the binder resin monomer. Get it at least. The emulsion polymerization aggregation type chemical toner is obtained by aggregating a thermoplastic resin emulsion, a wax emulsion, pigment particles and CCA particles to a particle size of 5 to 10 μm.

  The most important condition for obtaining a clear developed image using these toners is that the toners are uniformly charged with the same polarity. Conventionally, such uniformly charged toner contains CCA in the toner, such as carrier particles for transporting the toner to the electrostatic latent image surface, a developing roll or a charging blade attached on the developing roll. It is obtained by mixing or rubbing with the charging member.

  The amount of triboelectric charge that the toner acquires is governed by the CCA particles present on the toner surface. For this reason, an attempt has been made to allow a desired amount of CCA to be present on the toner surface rather than kneading into the toner.

  For example, in JP-A-2-73371 and JP-A-2-161471, an attempt is made to mechanically embed CCA in the toner surface using a Henschel mixer or a hybridizer (see Patent Documents 1 and 2). ).

  In JP-A-5-127423 and JP-A-2004-220005, an attempt is made to fix the fine CCA particles to the toner surface (see Patent Documents 3 and 4). Japanese Patent Application Laid-Open No. 5-134457 discloses a method in which a CCA solution is deposited on the surface of a toner and further refined to coat CCA particles (see Patent Document 5).

  In JP-A-5-341570, a toner, water-dispersible small particles having an average particle diameter of 0.01 to 0.2 [mu] m and an aqueous CCA dispersion are mixed, and this dispersion is used to produce a toner surface. An attempt has been made to form a CCA-containing small particle layer strongly adhered to the surface (see Patent Document 6). Furthermore, in Japanese Patent Application Laid-Open No. 2004-109406, a charge control agent is dispersed in small particles having an average particle diameter of 0.1 to 0.8 μm on the toner surface, or the charge control agent is attached to the surface of the small particles. An electrostatic image developing toner in which the small particles thus fixed are fixed on the toner surface is disclosed (see Patent Document 7).

  In general, developing toner is consumed by developing an electrostatic latent image in contact with the electrostatic latent image surface. The toner consumed in the development process is newly replenished, rubs against the charging member again, and the development process is repeated. In other words, while the above-described development / replenishment operation continues constantly, the toner can always acquire a constant charge amount and continue development.

  By the way, dry developers used in electrophotography and the like can be roughly classified into a one-component developer using a toner itself in which a colorant is dispersed in a binder resin and a two-component developer in which a carrier is mixed with the toner. . When performing copy operations using these developers, in order to have process compatibility, not only the chargeability but also the developer is excellent in fluidity, caking resistance, fixing properties, cleaning properties, etc. is required.

  In particular, in order to improve fluidity, caking resistance, fixability, and cleaning properties, inorganic fine particles are often added to the toner surface as an external additive. However, the dispersibility of the inorganic fine particles has a great influence on the toner characteristics, and when the dispersibility is not uniform, desired characteristics cannot be obtained in the fluidity, caking resistance, and fixability, or the cleaning properties are insufficient. As a result, toner sticking or the like may occur on the photoconductor, which may cause black spot image defects. For the purpose of improving these problems, various inorganic fine particles whose surface has been subjected to a hydrophobic treatment have been proposed, and many silica fine particles whose surface has been subjected to a hydrophobic treatment have been proposed.

  The synthetic silica fine particles, which are the base of the hydrophobized silica fine particles, are produced by combusting the combustion method silica (that is, fumed silica) obtained by burning the silane compound and the metal silicon powder explosively. Decombustion silica obtained, wet silica obtained by neutralization reaction between sodium silicate and mineral acid (of which, silica gel synthesized and aggregated under alkaline conditions is precipitated silica, silica gel synthesized and aggregated under acidic conditions is gel Silica method), colloidal silica (silica sol) obtained by polymerizing acidic silicic acid obtained by sodium removal from sodium silicate with an ion exchange resin, and sol-gel method obtained by hydrolysis of hydrocarbyloxysilane (So-called Stober method silica).

  As a hydrophobizing method, hydrophobizing treatment is performed by bringing a silica fine particle powder into contact with a hydrophobizing agent such as a surfactant, silicone oil, or a silylating agent such as alkylhalogenosilane, alkylalkoxysilane, or alkyldisilazane. And a hydrophobization treatment by contacting with a silylating agent in a mixed solvent of water and a hydrophilic organic solvent.

  And the hydrophobization process which uses a precipitation method silica and a fumed silica as a silica raw material is known so that it may demonstrate below.

An aqueous suspension of hydrophilic precipitated silica is prepared in the presence of a catalytic amount of an acid and an organosilane compound and a sufficient amount of a water-miscible organic solvent to promote the reaction between the organosilicon compound and the hydrophilic precipitated silica. A method for producing hydrophobic precipitated silica by contact (refer to Patent Document 8), fumed silica having an average primary particle diameter of 5 to 50 nm is surface-treated with hexamethyldisilazane, and 40% of silanol groups on the particle surface are formed. A method of obtaining silicon oxide particles that are blocked as described above and having a residual silanol group concentration of 1.5 particles / nm ² or less (see Patent Document 9), and fumed silica is hydrophobized with an organosilicon compound such as hexamethyldisilazane. The aggregated particles having a bulk density of 80 to 300 g / l, OH groups per unit surface area of 0.5 / nm ² or less, and a particle diameter of 45 μm or more are 2000 ppm. A method of obtaining hydrophobic fumed silica as described below (see Patent Document 10), a method of treating fumed silica with polysiloxane, and then treating with a trimethylsilylating agent (see Patent Document 11) ) Highly dispersed hydrophobic silica powder by subjecting fumed silica to a primary surface treatment with a silicone oil-based treatment agent, pulverization after the primary surface treatment, and secondary surface treatment with an alkylsilazane-based treatment agent after pulverization There is a method of obtaining (see Patent Document 12).

  However, in any of the hydrophobization methods, when precipitated silica or fumed silica is used, there is no description of the relationship between the primary particle size of the silica raw material and the aggregated particle size after the hydrophobization treatment. Since the active ingredient itself is aggregated, a hydrophobic silica powder having excellent fluidity and dispersibility could not be obtained.

  On the other hand, a method of hydrophobizing a silica sol as a starting material using a silica sol having a good dispersibility is also known. Silica sol is dispersed in an organic solvent such as alcohol or water and reacted with a silylating agent such as alkylhalogenosilane, alkylalkoxysilane, or alkyldisilazane, and then the organic solvent or water is removed to obtain hydrophobic silica powder. ing. Specifically, examples of the technology disclosed below can be given.

A silylating agent is added to butanol-dispersed silica sol having a water content of 10% or less, and after the reaction, the solvent is distilled off, and the silyl group having 1 to 36 carbon atoms is bonded to the surface of the colloidal silica particle by 1 to 100/10 nm ² A method for obtaining silica powder redispersible in an organic solvent (see Patent Document 13), adding hydrophilic colloidal silica having an average particle diameter larger than 4 nm to a mixed solvent of concentrated hydrochloric acid, isopropanol and hexamethyldisiloxane. Hydrophobic treatment, followed by extraction of hydrophobic colloidal silica with a hydrophobic organic solvent, heating and refluxing, adding a silane compound, heating and refluxing to perform hydrophobic treatment, and obtaining hydrophobic non-aggregated colloidal silica (Patent Document) 14), a disilazane compound is added to an aqueous silica sol containing hydrophilic colloidal silica, and the mixture is aged by heating in a temperature range of 50 to 100 ° C. There is a method of obtaining a hydrophobic silica powder by obtaining a slurry dispersion of hydrophobized colloidal silica and drying it (see Patent Document 15).

  However, when these silica sols are used in any of the hydrophobization methods, the particle size after the hydrophobization treatment does not maintain the primary particle size of the silica raw material and is agglomerated when obtained as a powder. Thus, hydrophobic silica powder having excellent fluidity and dispersibility could not be obtained. In addition, the colloidal silica obtained by patent document 14 judges the presence or absence of aggregation by observation with a transmission electron microscope. Usually, the sample used for this observation is dried under the condition that the agglomeration does not occur at a large dilution, so the presence or absence of agglomeration in the toluene dispersion state can be judged, but in an industrial drying process where the silica is at a high concentration. It cannot be determined whether the obtained powder is agglomerated. Therefore, although this colloidal silica maintains the primary particle diameter in the toluene dispersion state, it is considered that the colloidal silica is aggregated as in Patent Document 15 when taken out as a powder.

  In recent years, the performance of the silica particle powder as a toner external additive has been sufficient because an organic photoreceptor or a toner having a smaller particle diameter is used in order to achieve higher image quality. It is not a thing. In addition, organic photoreceptors have a softer surface and higher reactivity than inorganic photoreceptors, so their lifetime is likely to be shortened. Therefore, when such an organic photoreceptor is used, the photoreceptor is easily altered or scraped by the inorganic fine particles added to the toner. Furthermore, when the toner has a small particle size, the powder fluidity is poor as compared with a toner having a particle size that is usually used, so a larger amount of inorganic fine particles must be added. May cause toner adhesion to the photoreceptor.

  In addition, a method is also known in which a sol-gel silica having good dispersibility is used as a silica raw material to perform hydrophobicity. Solgel silica is dispersed in an organic solvent such as alcohol or water, and after reacting with a silylating agent such as alkylhalogenosilane, alkylalkoxysilane, or alkyldisilazane, the organic solvent or water is removed, and hydrophobic silica powder is obtained. Has been obtained. Specifically, examples of the technology disclosed below can be given.

  To the spherical silica particle methanol dispersion obtained by hydrolyzing tetramethoxysilane in methanol in the presence of ammonia water, methoxytrimethylsilane or hexamethyldisilazane is added, and the excess silylating agent is recovered and dried. To obtain hydrophobized spherical silica fine particle powder (see Patent Literature 16 and Patent Literature 17), and hydrolyzing a tetraalkoxysilane compound in the presence of a basic substance to prepare an aqueous dispersion of hydrophilic spherical silica fine particles. The alcohol is removed, the spherical silica fine particles are hydrophobized with an alkyltrialkoxysilane compound, the solvent is replaced with a ketone solvent, and the reactive groups remaining on the surface of the spherical silica fine particles are replaced with a silazane compound or a trialkylalkoxysilane compound. Triorganosilylation, and finally the solvent is distilled off under reduced pressure. Management spherical silica microparticles process for obtaining (Patent Document 18, Patent Document 19) are known.

  When these sol-gel silicas are used in any of the hydrophobization methods, when the powder is obtained as a powder, it is possible to obtain a product in which the particle size after the hydrophobization treatment maintains the primary particle size of the silica raw material. A hydrophobic spherical silica fine particle powder having excellent fluidity and dispersibility was obtained.

JP-A-2-73371 JP-A-2-161471 Japanese Patent Laid-Open No. 5-127423 JP 2004-220005 A JP-A-5-134457 Japanese Patent Laid-Open No. 5-341570 JP 2004-109406 A JP 2000-327321 A Japanese Patent Application Laid-Open No. 07-286095 JP 2000-256008 A JP 2002-256170 A JP 2004-168559 A JP 58-145614 A JP 2000-80201 A JP 2006-169096 A Japanese Patent Laid-Open No. 03-187913 JP 2001-194824 A JP 2000-44226 A JP 2000-330328 A

  However, in actuality, even when the techniques of Patent Documents 1 to 7 in which CCA is added and adjusted are used, the toner that is rubbed but remains undeveloped and remains in the developing unit, and the surface of the charging member by the frictional operation with the toner There has been a problem that the toner charge amount gradually changes due to contamination and the like, and when developing operations are repeated, the developed image quality gradually deteriorates.

  It is considered that the deterioration of the developed image is affected by the change in the composition of the toner surface and the charging member surface by repeating the development / friction process. In other words, in order to always maintain a constant amount of triboelectric charge even if the toner is repeatedly subjected to frictional mixing, development, and replenishment, it is necessary that the amount of CCA in the surface composition of the toner is always maintained constant. Because there is.

  Actually, (1) the amount of CCA on the toner surface becomes excessive or insufficient due to the toner developing operation or the friction / mixing operation between the toner and the charging member in the developing unit. (2) The CCA on the toner surface is charged by the charging member. It is difficult to always keep the CCA amount on the toner surface constant because it migrates to the surface and becomes contaminated, or (3) the CCA on the toner surface is buried inside the toner. As a result, when the toner is used for a long period of time, the charge amount of the toner gradually changes and the problem that the image deteriorates inevitably occurs, and these problems have not yet been completely solved.

  On the other hand, as described in Patent Documents 8 to 19, the spherical silica fine particle powder has good dispersibility and fluidity as a toner external additive, and imparts necessary fluidity and caking resistance to the toner. However, since silica itself exhibits a strong negative chargeability, even if it is added to the toner after a surface treatment that replaces it with the positive chargeability, the desired charge amount can be stabilized with the positive chargeability of the toner. It is difficult to provide a charge imparting function to maintain the charge amount, and particularly when the developer is mixed for a long period of time, the charge amount largely changes due to the toner fine powder generated because the silica powder acts as an abrasive. It was.

  Therefore, the present invention adds the charge control function of the CCA while maintaining excellent fluidity and excellent dispersibility in the conventional electrostatic image developing toner, so that the friction charge polarity as well as the friction charge polarity is added. By making it possible to adjust the charge amount with high accuracy, the amount of CCA particles existing on the toner surface is kept within a certain range, and thus the frictional charge amount generated between the toner and the carrier is kept within a certain range. An object of the present invention is to provide an electrostatic image developing toner which is less likely to deteriorate even when used for a long period of time, and which can impart excellent fluidity and anti-caking property as a toner.

  As a result of intensive studies to solve the above problems, the present inventors have determined that a predetermined amount of CCA is applied to the surface of the carrier particles obtained by hydrophobizing the surface of the hydrophilic spherical silica fine particles obtained by the sol-gel method. The present invention has found that an externally added charge control particle and a toner for electrostatic image development in which a predetermined amount of the externally added charge control particle is added to the toner can solve the above problems. completed.

That is, in the electrostatic image developing toner of the present invention, a charge control agent (CCA) is applied to the surface of toner particles and carrier particles having an average particle diameter of 20 to 500 nm, which is used for controlling the triboelectric charge amount of the toner particles. An electrostatic image developing toner obtained by mixing a charge control particle for external addition that has been applied, wherein the charge control particle for external addition hydrophobizes the surface of hydrophilic spherical silica fine particles obtained by a sol-gel method. An electrostatic image developing toner comprising transport particles made of hydrophobic spherical silica fine particles having an average particle diameter of 20 to 500 nm obtained by the treatment, and a charge control agent deposited on the surfaces of the transport particles. Charge control particles for external addition for controlling the triboelectric charge amount, and the charge control agent (CCA) is in a range of 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass with respect to 1 part by mass of the transport particles. Have In addition, 0.001 to 0.05 parts by mass of the charge control particles for external addition are mixed with 1 part by mass of the toner particles.

The externally added charge control particles of the present invention are transported of hydrophobic spherical silica fine particles having an average particle diameter of 20 to 500 nm obtained by hydrophobizing the surface of hydrophilic spherical silica fine particles obtained by the sol-gel method. Charge control particles for external addition for controlling the triboelectric charge amount of electrostatic image developing toner comprising particles and a charge control agent deposited on the surface of the carrier particles, the charge control agent In the range of 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass with respect to 1 part by mass of the carrier particles.

  The charge control particles for external addition formed by depositing a small amount of CCA on the surface of the carrier particles of the present invention are fine particles for charge control having both excellent fluidity, water repellency, abrasiveness reducing effect, charge imparting effect, In addition to imparting excellent fluidity and anti-caking property to the electrostatic image developing toner to which the toner is added, it is possible to impart a desired charge polarity and a desired charge amount to the toner.

  In addition, the electrostatic image developing toner to which the externally added charge control particles of the present invention are added realizes an excellent rise in charge amount and maintenance of a constant charge amount, and the developer and the charging member under high humidity. Even after repeating the mixing and stirring operation or the development / replenishment operation, the constant charge amount can be maintained, and the development operation can be performed without causing deterioration of the development quality.

FIG. 6 is a diagram illustrating a relationship between toner mixing time and toner charge amount in Examples 1 to 7 and Comparative Examples 1 and 2. FIG. 6 is a diagram illustrating a relationship between toner mixing time and toner charge amount in Examples 8 to 13 and Comparative Examples 1 and 2. FIG. 6 is a graph showing the relationship between toner mixing time and toner charge amount in Examples 14 to 19 and Comparative Examples 1 and 2. FIG. 6 is a graph showing the relationship between toner mixing time and toner charge amount in Examples 20 to 24 and Comparative Examples 2 and 3;

  The hydrophobic spherical silica fine particles used in the present invention are hydrophobic spherical silica fine particles having an average particle diameter of 20 to 500 nm obtained by hydrophobizing the surface of hydrophilic spherical silica fine particles obtained by the sol-gel method.

The hydrophobic spherical silica microparticles, tetrafunctional silane compound and / or R ² SiO its partial hydrolysis condensation product on the surface of the hydrophilic spherical silica microparticles composed of the obtained SiO ₂ units by hydrolysis and condensation _3/2 units (wherein R ² is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) and R ¹ ₃ SiO _1/2 units (wherein R ¹ is the same or different) And a monovalent hydrocarbon group having 1 to 6 carbon atoms.) Obtained by hydrophobic treatment.

  An example of a more specific method for producing the hydrophobic spherical silica fine particles is as described below.

First, a silane compound represented by the general formula (I): Si (OR ³ ) ₄ (wherein R ³ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms) and hydrolytic condensation thereof. Hydrophilic spheres by hydrolyzing and condensing one or more compounds selected from the products in a mixed solution of hydrophilic compounds such as methanol and ethanol, water, and basic compounds such as ammonia and organic amines A step of obtaining a silica fine particle dispersion is performed.

  A step of adding water to the obtained hydrophilic spherical silica fine particle dispersion, distilling off the hydrophilic solvent and converting it into an aqueous dispersion, and completely hydrolyzing the alkoxy groups remaining on the surface of the fine particles is performed.

Next, the hydrophilic spherical silica fine particle aqueous dispersion thus treated is added to the general formula (II): R ² Si (OR ⁴ ) ₃ (where R ² is a monovalent hydrocarbon having 1 to 20 carbon atoms). Group, R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms) and one or two or more compounds selected from hydrolytic condensates thereof are added to make hydrophilic A step of coating the surface of the spherical silica fine particles to obtain hydrophobic spherical silica fine particles is performed.

  Further, a step of adding a ketone solvent to the hydrophobic spherical silica fine particle aqueous dispersion and distilling off water to convert it into a hydrophobic spherical silica fine particle ketone solvent dispersion is performed.

Finally, in the hydrophobic spherical silica fine particle ketone solvent dispersion, the general formula (III): R ¹ ₃ SiNHSiR ¹ ₃ (wherein R ¹ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms) And a general formula (IV): R ¹ ₃ SiX (where R ¹ is the same as in general formula (III), X is an OH group or a hydrolyzable group). Hydrophobic spherical silica fine particles suitable for the present invention can be obtained by adding a compound selected from silane compounds and reacting them to make the silanol groups remaining on the surface of the silica fine particles trialkylsilylated and further hydrophobized. can get.

  Here, specific examples of the tetrafunctional silane compound represented by the general formula (I) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Specific examples of the partial hydrolysis-condensation product of the tetrafunctional silane compound represented by the general formula (I) include methyl silicate and ethyl silicate.

  The hydrophilic organic solvent is not particularly limited as long as it dissolves the compound of the general formula (I) or a partially hydrolyzed condensate thereof and water, and cellosolves such as alcohols, methyl cellosolve, ethyl cellosolve, butyl cellosolve, and cellosolve acetate. , Ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and tetrahydrofuran, and alcohols are preferable.

Examples of alcohols include alcohol solvents represented by the general formula (V): R ⁶ OH (V) (where R ⁶ is a monovalent hydrocarbon group having 1 to 6 carbon atoms), and specific examples thereof. Examples include methanol, ethanol, isopropanol, and butanol. As the number of carbon atoms in the alcohol increases, the particle size of the silica fine particles to be generated increases, so it is desirable to select the type of alcohol according to the particle size of the target silica fine particles.

  Examples of the basic compound include ammonia, dimethylamine, diethylamine and the like, and preferably ammonia. These basic compounds may be dissolved in water in a required amount, and the obtained aqueous solution (basic water) may be mixed with a hydrophilic organic solvent.

  The amount of water used at this time is preferably 0.5 to 5 mol with respect to 1 mol of the alkoxy group of the silane compound of the general formula (I) or a partially hydrolyzed condensate thereof, and water and a hydrophilic organic solvent Is preferably 0.5 to 10 in terms of mass ratio, and the amount of the basic compound is 0.01 to 1 mol per 1 mol of the alkoxy group of the silane compound of the general formula (I) or its partial hydrolysis condensate. It is preferably 1 mole.

  Hydrolysis and condensation of a tetrafunctional silane compound or the like of the general formula (I) is a well-known method in which the tetrafunctional silane compound of the general formula (I) is dropped into a mixture of a hydrophilic organic solvent containing a basic compound and water. Is done by. In order to convert the dispersion medium of the silica fine particle mixed solution dispersion into water, for example, an operation of adding water to the dispersion and distilling off the hydrophilic organic solvent (repeating this operation as necessary) can be performed. . The amount of water added at this time is 0.5 to 2 times, preferably about 1 time, in terms of mass ratio with respect to the total amount of the hydrophilic organic solvent used and the amount of alcohol produced.

  Specific examples of the trifunctional silane compound represented by the general formula (II) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, and n-propyltrimethoxysilane. Trialkoxy such as ethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane Silane may be mentioned, and these partially hydrolyzed condensates may be used.

The addition amount of the trifunctional silane compound represented by the general formula (II) is 1 to 0.001 mol, preferably 0.1 to 0.01 mol, per 1 mol of SiO ₂ unit of the hydrophilic spherical silica fine particles used. It is good to use.

  In the step of converting the dispersion medium of the hydrophobic spherical silica fine particle aqueous dispersion into the ketone solvent, an operation of adding the ketone solvent to the dispersion and distilling off the water (repeating this operation as necessary) is performed. . The amount of the ketone solvent added at this time is 0.5 to 5 times, preferably 1 to 2 times the mass ratio of the hydrophilic spherical silica fine particles used. Specific examples of the ketone solvent used here include methyl ethyl ketone, methyl isobutyl ketone, acetylacetone and the like, preferably methyl isobutyl ketone.

  Specific examples of the silazane compound represented by the general formula (III) include hexamethyldisilazane. Specific examples of the monofunctional silane compound represented by the general formula (IV) include trimethylsilanol and triethylsilanol. Monosilanol compounds, monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane, monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane, monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine, and monoacyloxysilanes such as trimethylacetoxysilane .

These are used in an amount of 0.1 to 0.5 mol, preferably 0.2 to 0.3 mol, based on 1 mol of SiO ₂ units of the used hydrophilic spherical silica fine particles.

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

  The hydrophobic spherical silica fine particles used in the present invention have a highly hydrophobic surface, no reactive groups such as silanol groups remain, high dispersibility, low agglomeration, and good fluidity. It gives good results to the purpose and effect.

  The particle size of the fine particles is 20 to 500 nm, preferably 50 to 200 nm, from the viewpoint of improving the flowability, caking resistance and fixability of the developer and reducing the adverse effect on the photoreceptor. If the particle size is smaller than 20 nm, the fluidity, caking resistance, and fixing property of the developer cannot be obtained due to aggregation, and if it exceeds 500 nm, there are disadvantages such as modification of the photoreceptor, scraping, and reduction in adhesion to the toner. Here, “particle diameter” means a volume-based median diameter, and the average particle diameter of the carrier particles in the present specification is determined by particle size distribution measurement by a dynamic light scattering method / laser Doppler method.

  This fine particle uses a silane having a small number of carbon atoms in the tetraalkoxysilane, uses an alcohol having a small number of carbon atoms as a solvent, raises the hydrolysis temperature, and lowers the concentration during hydrolysis of the tetraalkoxysilane. It can be obtained with a smaller particle size by changing reaction conditions such as reducing the concentration of the hydrolysis catalyst.

  With respect to the hydrophobic spherical silica fine particles used in the present invention, “spherical” includes not only true spheres but also slightly distorted spheres. Note that the shape of such particles is evaluated by the circularity when the particles are projected two-dimensionally, and the circularity is in the range of 0.8 to 1. Here, the circularity is (peripheral length of a circle equal to the particle area) / (peripheral length of particle). This circularity can be measured by image analysis of a particle image obtained with an electron microscope or the like.

  The fine particles may be further surface-treated with various silane coupling agents and silanes such as dimethyldimethoxysilane as necessary.

  The CCA used in the present invention has an electron accepting group such as a sulfone group, a carboxyl group, a phenolic hydroxyl group, a phosphoric acid group, a nitro group, and a cyano group in the molecule, or an amino group, an alkylamino group, a quaternary ammonium group, and the like. An organic compound having an electron donating group, or an organic compound formed with a salt or complex with these polar groups. Counter ions for forming salts or complexes with electron donating or electron accepting polar groups are not limited to organic ions, such as metal ions, metal oxide ions, halogen ions, quaternary ammonium ions, etc. There may be.

This CCA becomes particulate CCA particles and is deposited on carrier particles described later, and the CCA particles include those having a molecular size or a size close to the molecular size. Although most of those conventionally marketed as CCA are contained in the above organic compounds, the CCA of the present invention is not limited thereto. For example, a resin having a molecular weight of 1 × 10 ³ to 1 × 10 ⁵ in which 0.01 mmol% or more of an electron donating or electron accepting polar group is introduced into the main chain or side chain, or the polar group of these resin molecules is a salt or A resin forming a complex, a low molecular weight organic compound having a molecular weight of 100 to 1,000, and having at least one electron-donating or electron-accepting polar group, or a polar group and a salt thereof; An organic compound having a complex structure can also be used as the CCA of the present invention.

In the externally added charge control particles of the present invention, the CCA particles are 1 × 10 ⁻³ to 1 × 10 ^{−1 with} respect to 1 part by mass of the hydrophobic spherical silica fine particles (hereinafter referred to as carrier particles). It adheres to the surface of the transport particles in the range of part by mass, improves the flowability, caking resistance and fixability of the electrostatic image developing toner, reduces the adverse effect on the photoreceptor, and further controls the triboelectric charge amount. Used as external charge control particles.

  The charge control particles for external addition according to the present invention are mixed with toner particles (colored resin fine particles) to form an electrostatic image developing toner. The toner particles used here are colored resin particles having a particle diameter of 2 to 20 μm and a volume average particle diameter of about 5 to 10 μm formed by containing colored fine particles in thermoplastic resin particles. Also included in this category are particles containing a wax or the like to improve the fluidity, and to which ultrafine silica powder is externally added to the surface to improve fluidity. The colored resin particles can be obtained by a pulverization method obtained by melt-kneading thermoplastic particles, a colorant, wax, and the like, and then pulverizing and classifying them to obtain particles of a desired particle size, and adding silica powder or the like thereto. In addition, like particles called chemical toners, a colorant and wax are dispersed in a monomer, and the dispersion is suspended and polymerized in water. Fine particles of thermoplastic resin, colorant and wax dispersed in water are used. It can also be obtained by agglomerating or emulsifying resin particles and wax particles and a colorant. In addition, the particle size of the colored resin particles in the present specification is determined by a Coulter counter method.

  The charge control particles for external addition in the electrostatic image developing toner of the present invention are desirably added in the range of 0.001 to 0.05 parts by mass with respect to 1 part by mass of the toner particles. When the added external charge control particles are less than 0.001 part by mass, the external charge control particles are only sparsely deposited on the surface of the toner particles, so that the desired fluidity cannot be obtained. When the amount of the externally added charge control particles exceeds 0.05 parts by mass, free externally added charge control particles that cannot be deposited on the surface of the toner particles may cause contamination of the developing member, photoconductor, or in-machine. In addition, the charge control performance of the toner is deteriorated.

In the charge control particles for external addition of the present invention, the CCA particles to be deposited on the surface of 1 part by mass of the carrier particles are in the range of 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass, and the carrier particles are added to ¹ part by mass of the toner particles. The CCA particles carried by are selected in the range of 1 × 10 ^{−6 to} 5 × 10 ⁻³ parts by mass, preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻³ parts by mass. It can be seen that the carrier particles work to supply such a very small amount of CCA to the toner particle surface with high accuracy. The reason why the charge amount of the toner is governed by such a very small amount of CCA is that the charge control particles for external addition according to the present invention use CCA having a size close to the molecular size deposited on the surface of the carrier particles as the toner particles. It is thought that it originates in being able to supply to the surface. For example, assuming that the CCA having a molecular weight of 10,000 deposited on the surface of the carrier particle is 1 × 10 ⁻⁵ parts by mass, assuming that all the deposited CCA molecules are supplied to the toner surface in an ionized state, this molecular ion is The charge amount of 1 part by mass of toner particles can be shifted in the negative or positive direction by 100 μC / g. As shown in Examples described later, when the external addition CCA particles of the present invention are added to the toner, a value close to the theoretical charge application amount can be confirmed.

The extremely small amount of CCA particles carried by the carrier particles on the surface of the toner particles is preferably in the range of 1 × 10 ^{−6 to} 5 × 10 ⁻³ parts by mass with respect to 1 part by mass of the toner particles, and part or most of the CCA particles are more than the carrier particles. It is desirable that the particle size is small or close to the molecular size, either deposited on the surface of the carrier particle or coated on the surface of the carrier particle, but one part of the CCA particle is not deposited on the carrier particle and is free May be present as particles. The charge control particles for external addition consisting of such carrier particles and CCA are finely dispersed or dissolved in a liquid such as water or an organic solvent, and then applied to the surface of the carrier particles by applying a coacervation method. Obtained by coating CCA. Also, the CCA solution or dispersion is atomized and sprayed on the carrier particles in a fluid state, the CCA solution or dispersion is added while stirring the carrier particle dispersion, and the CCA solution or dispersion and carrier particles are mixed. It can be produced by applying a mechanochemical method such as post-drying and crushing, or mixing while applying compression or shear stress to the mixture of CCA and carrier particles.

  In the externally added charge control particles thus obtained, there are sometimes free CCA particles that are not deposited on the surface of the carrier particles and may be mixed with the carrier particles. Even in such a case, the present invention sufficiently exhibits the function as the charge control particles for external addition. Although the reason for this has not been clarified, in the process in which the charge control particles for external addition are supplied to the surface of the toner particles and are rubbed and mixed with the charging member, the free CCA particles present at the interface between the toner particles and the charging member are This is probably because the particles are ground by charging members and carrier particles to become small particles, and sometimes change to particles close to the molecular size.

As described above, the CCA particles carried by the carrier particles to 1 part by mass of the toner particles are in the range of 1 × 10 ^{−6 to} 5 × 10 ⁻³ parts by mass, preferably 1 × 10 ⁻⁵ to 1 × 10 ⁻³ parts by mass. Thus, the effect of the present invention is exhibited by being supplied in the form of externally added charge control particles. According to the present inventors, the toner charge amount is stably controlled simply by externally adding a very small amount of CCA of 1 × 10 ^{−6 to} 5 × 10 ⁻³ parts by mass with respect to 1 part by mass of toner particles. It was confirmed that it was impossible.

  The mechanism by which the CCA particles supplied by the carrier particles in the present invention dominate the toner charging has not been completely elucidated. However, the charge control mechanism can be understood when considered as follows. First, some of the CCA particles transported by the transport particles come into contact with the surface of a charging member such as a carrier, and are charged (ionized) by exchanging charges with the carrier surface. The charged particle ions move to the toner particle surface alone or in a state of adhering to the surface of the carrier particle, and are re-deposited on the toner particle surface to charge the toner. At this time, since the number of ionized CCA particles is close to the number of CCA molecules and is overwhelmingly larger than the number of transport particles, the triboelectric charge amount of the transport particles obtained when the transport particles rub against the charging member can be ignored. Therefore, it is considered that the toner charge amount is governed by the number of CCA particles far exceeding the number of transport particles deposited on the surface of the transport particles, regardless of the weight of the transport particles.

  As the toner particles to which the above externally added charge control particles are added, known toner particles composed mainly of a binder resin and a colorant can be used. The externally added charge control particles may be adhered to the surface of the toner particles simply by mechanical adhesion or by loose adhesion. Further, the adhered particles may cover the entire surface of the toner particles or only a part thereof. Further, the particles may partially form aggregates and cover the surface of the toner particles, but it is preferable that the particles are covered in the form of single layer particles.

  The electrostatic image developing toner to which the externally added charge control particles of the present invention are added can be used as a one-component developer. It can also be mixed with a carrier and used as a two-component developer. When used as a two-component developer, the charge control particles for external addition may not be added to the toner particles in advance, but may be added when the toner and the carrier are mixed to cover the surface of the toner. As the carrier, iron powder or ferrite powder having a particle diameter of 20 μm to 100 μm, or a known one whose surface is resin-coated is used.

  According to the externally added charge control particles of the present invention thus obtained, an excellent flow of the hydrophobic spherical silica fine particles obtained by the sol-gel method is obtained by using this as an external additive as an electrostatic image developing toner. The charge control function of CCA is added to the toner particle surface while maintaining the properties of the toner and the excellent dispersibility. Thus, it is possible to provide an electrostatic image developing toner in which the number of CCA particles present in the toner can be kept constant, and the desired triboelectric charge amount can be stably maintained.

  In addition, the present invention makes it possible to very easily apply the external charge control particles having high fluidity and water repellency to the surface of the toner particles by depositing a desired amount of CCA particles on the surface of the carrier particles with high accuracy. In addition to supplying a constant amount of CCA particles, an electrostatic image developing toner that can maintain a constant charge amount even when used in a high humidity atmosphere can be provided.

  Furthermore, the present invention uses externally added charge control particles that can uniformly and extremely accurately supply a very small amount of CCA particles having an extremely large amount of generated charge per unit weight on the toner surface. As a result, it is possible to provide an electrostatic image developing toner in which the rising of charge is remarkably fast in both the two-component developer and the one-component developer, and the charge amount is not changed by the friction operation.

  Further, in the electrostatic image developing toner of the present invention, the charge control particles for external addition exist in a state where they are electrostatically attracted to the toner particles and physically adhered to the toner surface, but are not fixed. . Therefore, when the mixture of externally added charge control particles and toner particles is rubbed against a charging member such as carrier particles, the externally added charge control particles are easily separated from another toner particle surface or charging member such as carrier particles. It is characterized by being able to move freely to the surface. For this reason, the externally added charge control particles of the present invention can transfer CCA particles to a plurality of toner particles, and this degree of freedom is considered to contribute to uniform charge control.

  Further, such a degree of freedom can contribute not only to toner charge control, but also to improved toner transportability and improved toner surface wear resistance, as with conventional external additives.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the description, the measurement sample number corresponds to the example number.

<Example 1>
[Synthesis of hydrophobic spherical silica fine particles (1)]
(1) 6237 g of methanol, 414 g of water, and 498 g of 28% ammonia water were added to and mixed with a 30 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer. The solution was adjusted to 35 ° C., and 11637 g of tetramethoxysilane and 4181 g of 5.4% aqueous ammonia were simultaneously added while stirring. The former was added dropwise over 6 hours and the latter over 4 hours. After the tetramethoxysilane was dropped, the mixture was stirred for 0.5 hours for hydrolysis to obtain a silica fine particle suspension. Attach an ester adapter and a condenser to a glass reactor, heat to 60 to 70 ° C. and distill off 11320 g of methanol, add 12000 g of water, then heat to 70 to 90 ° C. to distill away 2730 g of methanol, An aqueous suspension of fine particles was obtained.

  (2) To this aqueous suspension, 116 g of methyltrimethoxysilane (equivalent to 0.1 molar ratio with respect to tetramethoxysilane) was added dropwise at room temperature over 0.5 hours, and after the addition, the mixture was stirred for 12 hours to obtain silica. The surface of the fine particles was treated.

  (3) After adding 14400 g of methyl isobutyl ketone to the dispersion thus obtained, the mixture was heated to 80 to 110 ° C. and methanol water was distilled off over 7 hours. To the obtained dispersion, 3576 g of hexamethyldisilazane was added at room temperature, heated to 120 ° C. and reacted for 3 hours to form trimethylsilylated hydrophobic silica fine particles (1), and then the solvent was distilled off under reduced pressure to convey the particles. 4770 g was obtained.

[Measurement of particle size of carrier particles]
The obtained hydrophobic spherical silica fine particles (1) were measured for particle size by adding the silica fine particles to methanol so that the amount was 0.5% by mass and applying ultrasonic waves for 10 minutes to disperse the fine particles. The particle size distribution of the fine particles treated in this way was measured by a dynamic light scattering method / laser Doppler nanotrack particle size distribution measuring device (trade name: UPA-EX150, manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter (particle size) The particle diameter corresponding to 50% cumulative when the distribution was expressed as a cumulative distribution) was taken as the particle diameter. As a result of the measurement, the median diameter obtained was 120 nm.

[Measurement of shape of carrier particles]
The shape was confirmed by observation with an electron microscope (manufactured by Hitachi, trade name: S-4700 type, magnification: 100,000 times). The shape of the carrier particles (hydrophobic spherical particles) of the present invention is defined as (circumference of a circle equal to the particle area) / (peripheral length of the particle) when projecting the particles in two dimensions, and the circularity is Those in the range of 0.8 to 1 were called spherical. As a result of the measurement, it was confirmed that the obtained carrier particles were spherical.

[Manufacture of charge control particles for external addition]
Into a Henschel mixer, 1 kg of hydrophobic spherical silica fine particles (1) (carrier particles) and 1 kg of heptane were added and mixed, and then a methanol solution (concentration 10.0) of CCA (1) (manufactured by Sartomer, trade name: PRO7058). 1 kg of a mass% liquid) was mixed.

The kneader was then heated to 60 ° C. and kneaded under reduced pressure to completely remove heptane and methanol. The obtained dried powder was crushed by a jet mill to obtain externally added charge control particles CCP1-1 in which 1 × 10 ⁻¹ parts by mass of CCA (1) particles per 1 part by mass were deposited on the carrier particles. It was.

[Preparation of toner containing charge control agent fine particles and adjustment of toner charge measurement sample]
1 part by mass of styrene acrylic resin model toner and 0.01 part by mass of charge control particles CCP1-1 for external addition were put into a Henschel mixer, and the peripheral speed of the stirring blade was agitated for 30 seconds at 40 m / sec. Toner 1 for charge control particles was obtained. Next, 1 part by mass of each externally added charge control particle-containing toner and 19 parts by mass of ferrite carrier were put into a V blender and mixed for 5 minutes to prepare a toner charge measurement sample 1.

[Measurement of toner charge amount]
Toner charge amount when the prepared measurement sample 1 was conditioned and mixed according to the standard of charge measurement of toner of the Imaging Society of Japan (Journal of Imaging Society of Japan 37, 461 (1998)) and the mixing time was changed. Was measured. A paint conditioner (manufactured by Toyo Seiki) was used for mixing, and a blow-off charge amount measuring device (trade name: TB203 type, manufactured by Toshiba Corporation) was used for toner charge amount measurement.

<Examples 2 to 7>
The concentration of CCA (1) in 1 kg of a methanol solution mixed with 1 kg of hydrophobic spherical silica particles (1) is 5.0% by mass, exactly the same as the process for producing CCP1-1 particles described in Example 1. External control charge control particles CCP1-2, CCP1-3, CCP1-4 prepared as 2.0 mass%, 1.0 mass%, 0.5 mass%, 0.25 mass%, 0.12 mass%. CCP1-5, CCP1-6, and CCP1-7 were prepared. Each is for external addition in which 0.05, 0.02, 0.01, 0.005, 0.0025 and 0.0012 parts by mass of CCA (1) particles are respectively deposited on the surface of 1 part by mass of the carrier particles. Charge control particles.

[Preparation of toner containing charge control agent fine particles and adjustment of toner charge measurement sample]
1 part by mass of styrene acrylic resin model toner and 0.01 part by mass of charge control particles CCP1-2 to CCP1-7 for external addition were put into a Henschel mixer, and the peripheral speed of the stirring blade was agitated for 30 seconds at 40 m / sec. Thus, toners 2 to 7 containing charge control particles for external addition were obtained. Next, 1 part by mass of each externally added charge control particle-containing toner and 19 parts by mass of ferrite carrier were put into a V blender and mixed for 5 minutes to prepare toner charge measurement samples 2 to 7. Using this developer, the toner charge amount was measured in the same procedure as in Example 1.

<Comparative Example 1>
[Adjustment of comparative measurement sample 1]
In the toner charge amount measurement sample, 0.01 parts by mass of carrier particles were added in place of the externally added charge control particles CCP1-1 to CCP1-7 to obtain Comparative Measurement Sample 1 (hereinafter referred to as Comparative Sample 1). Using this developer, the toner charge amount was measured in the same procedure as in Example 1.

<Comparative example 2>
[Adjustment of comparative measurement sample 2]
In the toner charge amount measurement sample, the sample to which neither the external charge control particles nor the carrier particles were added was designated as Comparative measurement sample 2 (hereinafter referred to as Comparative sample 2). Using this developer, the toner charge amount was measured in the same procedure as in Example 1.

[SEM observation of charge control particles for external addition and evaluation of measurement sample]
When the surfaces of the obtained charge control particles CCP1-1 to CCP1-7 for external addition were observed with a scanning electron microscope, the same smoothness as the spherical hydrophobic silica particles (carrier particles) used as the core was maintained. No free CCA (1) particles were found. Further, any of the externally added charge control particles obtained maintained water repellency, and methanol / water was added to a 50/50 weight ratio liquid mixture and floated on the liquid surface and could not be dispersed in the liquid. .

  Further, when the particles obtained by mixing each of the obtained external charge control particles and the model toner were observed by SEM, the external charge control particles were uniformly deposited on the toner surface in a monodispersed state. Confirmed that. Furthermore, the fluidity of the mixed powder is almost the same as that of the mixed powder of the carrier particles and the model toner, and the fluidity is remarkably improved compared to the model toner without adding the external charge control particles. It was confirmed that

[Toner charge measurement result]
FIG. 1 shows the charge amount measurement results of the toners obtained from each measurement sample and the comparative sample.

  From FIG. 1, when comparing the toner charge amounts obtained in Comparative Sample 1 and Comparative Sample 2, the toner charge amount of Comparative Sample 1 is negatively charged larger than the toner charge amount of Comparative Sample 2 and is added to 1 part by mass of model toner. It was found that the negative charge amount of the toner was increased by externally adding only 0.01 part by mass of hydrophobic spherical silica particles (carrier particles).

Next, when the toner charge amounts obtained in the measurement samples 1 to 7 are compared with the toner charge amounts obtained in the comparison sample 1 and the comparison sample 2, the toner charge amounts obtained in the measurement samples 1 to 7 are the comparison sample 1. It was found that the positive charge was larger than the charge amount of 2 and 2. From this result, it was confirmed that all of the externally added charge control particles (CCP1-1 to CCP1-7) imparted a large positive charge amount to the model toner. This result shows that when the charge control particles for external addition in which 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass of CCA (1) is applied to 1 part by mass of the transport particles are added to the model toner, the model toner is added. Compared with the case where only the carrier particles are added to the toner, the charge imparting effect on the toner is completely different. When the charge control particles for external addition are added, a much smaller amount of CCA (than the carrier particles deposited on the surface of the carrier particles) 1) It was confirmed that the charging characteristics were governed by the particles. In other words, in the measurement samples 1 to 7 to which the charge control particles for external addition (CCP1-1 to CCP1-7) are added, the carrier particles carry only 1 × 10 ⁻³ to the toner surface with respect to 1 part by mass of the toner. It was confirmed that ˜1.2 × 10 ⁻⁵ parts by mass of CCA (1) particles impart a sufficient positive charge amount to the toner and dominate the charging characteristics of the toner. That is, the result of FIG. 1 shows how the charge control particles for external addition according to the present invention exhibit the charge imparting effect of CCA (1) with high efficiency and high accuracy.

It can be seen from FIG. 1 that when any of the externally added charge control particles is added, the charge amount is already close to the peak value when the mixing time with the carrier is 2 minutes, and the rise of the charge is remarkably fast. Further, the rising of the charge is earlier with particles having a smaller CCA deposition amount on the surface of the carrier particles, and the deposition amount is 0.0012 parts by mass with respect to 1 part by mass of the carrier particles (1.2 parts by mass with respect to 1 part by mass of toner). X10 ⁻⁵ parts by mass) In the blended toner to which external charge control particles for external addition were added, the charge amount started to decrease in 2 minutes of mixing time, and the mixing time to reach the peak value was even shorter. Was confirmed.

  When the mixing time is increased, the negative charge amount of the toner slightly increases, but this increase is due to the charging of the toner fine powder generated by the mixing operation, and the gradient of the curve does not add the carrier particles or the external charge control particles. This was also confirmed from the same thing as the frictional charging of the toner only (Comparative Sample 2).

<Examples 8 to 13>
Charge control agent CCA (2) (trade name: Bontron P-51, manufactured by Orient Chemical Industry Co., Ltd.) is applied to the surface of the same carrier particles used in Example 1 in the same process as the deposition step in Example 1. Charge control ultrafine particles CCP2-1 coated with 0.05 parts by mass, 0.02 parts by mass, 0.01 parts by mass, 0.005 parts by mass, 0.002 parts by mass and 0.001 parts by mass, respectively. CCP2-6 was obtained.

[SEM observation of charge control particles for external addition and evaluation of measurement sample]
When the surfaces of the obtained charge control particles CCP2-1 to CCP2-6 for external addition were observed with a scanning electron microscope, the same smoothness as the spherical hydrophobic silica particles (carrier particles) used as the core was maintained. However, it was confirmed that slightly free CCA (2) particles were present. Also, any of the externally added charge control particles obtained maintained water repellency, and was able to disperse in methanol / water by adding methanol / water to a 50/50 weight ratio and floating on the liquid surface. There wasn't.

  Further, when the particles obtained by mixing each of the obtained external charge control particles and the model toner were observed by SEM, the external charge control particles were uniformly deposited on the toner surface in a monodispersed state. Confirmed that. Furthermore, the fluidity of the mixed powder is almost the same as that of the mixed powder of the carrier particles and the model toner, and the fluidity is remarkably improved compared to the model toner without adding the external charge control particles. It was confirmed that

[Toner charge measurement result]
The measurement result of the toner charge amount was as shown in FIG. The toner charge amount obtained from the measurement samples 8 to 13 in which the charge control particles for external addition (CCP2-1 to CCP2-6) in which a small amount of CCA (2) particles are deposited on the carrier particles is added is only the carrier particles. The positive charge amount of the comparative sample 1 to which the toner is added and the comparative sample 2 to which no particles are added is larger than the toner charge amount, and the carrier particles and the six kinds of externally added charge control particles impart a positive charge to the toner. It was confirmed that Although the charge control particles for external addition (CCP2-1 to CCP2-6) tend to slightly decrease the positive charge amount of the toner in the measurement samples 8 to 13 with the mixing time and increase the negative charge amount, this negative charge The amount increase rate is smaller than the negative charge amount increase rate in the comparative sample 2, and in the measurement samples 8 to 13 to which the charge control particles for external addition (CCP2-1 to CCP2-6) are added, as in Examples 1 to 7. , Only 5 × 10 ⁻⁴ to 1 × 10 ⁻⁵ parts by mass of CCA (2) particles conveyed to the toner surface with respect to 1 part by mass of toner impart a desired amount of positive charge to the toner, It was confirmed that it dominates the charging characteristics of the toner.

<Examples 14 to 19>
Charge control agent CCA (3) (manufactured by Fujikura Kasei Co., Ltd., trade name: FCA-201-PS) on the surface of the same carrier particles as used in Example 1, in exactly the same process as the deposition step in Example 1. Charge control ultrafine particles CCP3-1 coated with 0.05 parts by mass, 0.02 parts by mass, 0.01 parts by mass, 0.005 parts by mass, 0.002 parts by mass, and 0.001 parts by mass, respectively ~ CCP3-6 was obtained.

[SEM observation of charge control particles for external addition and evaluation of measurement sample]
When the surfaces of the obtained charge control particles CCP3-1 to CCP3-6 for external addition were observed with a scanning electron microscope, the same smoothness as the spherical hydrophobic silica particles (carrier particles) used as the core was maintained. However, it was confirmed that slightly free CCA (3) particles were present. In addition, any of the externally added charge control particles obtained maintained water repellency, and was able to disperse in methanol / water by adding methanol / water to a 50/50 mass ratio and floating on the liquid surface. There wasn't.

  Also, SEM observation of the particles obtained by mixing each of the obtained external charge control particles with the model toner confirmed that the external charge control particles were uniformly deposited on the toner surface. did. Furthermore, the fluidity of the mixed powder is almost the same as that of the mixed powder of the carrier particles and the model toner, and the fluidity is remarkably improved compared to the model toner without adding the external charge control particles. It was confirmed that

[Toner charge measurement result]
The measurement result of the toner charge amount was as shown in FIG. From the figure, when the toner charge amount obtained in Comparative Sample 1 to which only carrier particles are added is compared with Comparative Sample (2) in which neither the carrier particles nor the external charge control particles are added, Comparative Sample 1 shows a slight amount. The toner particles showed a large negative charge amount, and it was confirmed that the carrier particles imparted a negative charge amount to the toner.

On the other hand, the toner charge amount obtained in the measurement samples 14 to 19 in which the charge control particles for external addition (CCP3-1 to CCP3-6) in which a small amount of CCA (3) particles are deposited on the carrier particles is added, The positive charge amount was larger than the toner charge amount of Comparative Sample 2 to which no other particles were added, and it was confirmed that the six types of externally added charge control particles imparted a positive charge to the toner. The charge control particles for external addition (CCP3-1 to CCP3-6) have no tendency to change the positive charge amount of the toner in the measurement samples 14 to 19 at all with the mixing time or slightly decrease and increase the negative charge amount. However, the increase rate of the negative charge amount is smaller than the increase rate of the negative charge amount of the toner in Comparative Sample 2, and the charge control particles for external addition (CCP3-1 to CCP3-6) were added in the same manner as in Examples 1-7. In measurement samples 14 to 19, only 5 × 10 ⁻⁴ to 1 × 10 ⁻⁵ parts by mass of CCA (2) particles carried by the carrier particles on the toner surface with respect to 1 part by mass of the toner are in a desired amount. It was confirmed that the toner was given a positive charge amount and dominates the charging characteristics of the toner.

<Examples 20 to 24>
CCA (4) particles represented by the following chemical formula on the surface of 1 part by mass of carrier particles (2) (hydrophobic spherical silica fine particles) having an average particle diameter of 300 nm prepared in the same production steps of carrier particles as in Example 1 (Nippon Carlit Co., Ltd., trade name: LR147) 0.05 parts by mass, 0.02 parts by mass, 0.01 parts by mass, 0.005 parts by mass, and 0.001 parts by mass for external addition Charge control particles CCP4-1 to CCP4-5 were obtained.

  When the obtained charge control particles for external addition were observed by SEM, it was confirmed that the CCA (4) particles uniformly covered the surface of the carrier particles.

  Next, in the same manner as in Examples 1 to 7, measurement samples 20 to 24 were prepared by mixing 19 g of standard carrier N-02 (distributed by the Imaging Society of Japan) and 10 mg of CCP4-1 to CCP4-5 with 1 g of styrene acrylic resin model toner. In the same manner, the charge amount of blow-off toner when the mixing time was changed was measured.

  The charge amount measurement results are as shown in FIG. 4. The toner charge amount obtained in Comparative Sample 3 to which only the carrier particles (2) were added, and a small amount of CCA (4) particles were deposited on the carrier particles (2). When the toner charge amount obtained in the measurement samples 20 to 24 to which the externally added charge control particles CCP4-1 to CCP4-5 are added and the toner charge amount obtained in the comparative sample 2 are compared, the former is any particle. It was confirmed that the sample acted as a large negative charge imparting agent as the mixing time was increased with respect to the comparative sample 2 to which no addition was made. On the other hand, the toner charge amount obtained in the measurement samples 20 to 24 to which the charge control particles for external addition CCP4-1 to CCP4-5 are added has a negative charge amount from the comparison sample 2 depending on the amount of charge control particles for external addition. There were cases where it became larger and smaller. However, the charge amounts of toner obtained in these measurement samples 20 to 24 are much smaller than the change rate observed in the comparative sample 2 or the comparative sample 3 when the mixing time is changed, and the externally added charge control particles. It was confirmed that a desired negative charge amount can be imparted to the toner with high accuracy by adjusting the amount of toner deposited.

That is, from the results of FIG. 4, in the measurement samples 20 to 24 to which the charge control particles for external addition (CCP4-1 to CCP4-5) are added, the transport particles (2) are present on the toner surface with respect to 1 part by mass of the toner. Only 5 × 10 ⁻⁴ to 1 × 10 ⁻⁵ parts by mass of CCA (4) particles conveyed to the toner give a small negative charge amount to the model toner, but this negative charge even when the mixing time is changed. It was confirmed that the toner amount was kept stable and the toner charge amount was controlled with high accuracy.

  From the above, it has been found that the externally added charge control particles of the present invention in which CCA is deposited on the surface of the carrier particles can impart a sufficient amount of charge to the toner and control the electrical characteristics of the toner. At this time, according to the externally added charge control particles of the present invention, the change rate of the charge amount is small even when the mixing time of the toner is increased, and stable electrostatic image development can be performed even during long-term use. An electrostatic image developing toner can be obtained.

Claims (5)

Toner particles, and charge control particles for external addition in which a charge control agent (CCA) is deposited on the surface of carrier particles having an average particle diameter of 20 to 500 nm, used to control the triboelectric charge amount of the toner particles; An electrostatic image developing toner obtained by mixing
The external charge control particles are transport particles composed of hydrophobic spherical silica fine particles having an average particle diameter of 20 to 500 nm obtained by hydrophobizing the surface of hydrophilic spherical silica fine particles obtained by a sol-gel method, Charge control particles for external addition for controlling the triboelectric charge amount of the electrostatic image developing toner composed of a charge control agent deposited on the surface of the carrier particles, and with respect to 1 part by mass of the carrier particles The charge control agent (CCA) is in the range of 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass, and the externally added charge control particles are added to 1 part by mass of the toner particles. An electrostatic image developing toner obtained by mixing 0.001 to 0.05 parts by mass. The electrostatic image according to claim 1, wherein the charge control agent in the electrostatic image developing toner is 1 × 10 ⁻⁵ to 1 × 10 ⁻³ parts by mass with respect to 1 part by mass of toner particles. Development toner. Carrier particles composed of hydrophobic spherical silica fine particles having an average particle diameter of 20 to 500 nm obtained by hydrophobizing the surface of hydrophilic spherical silica fine particles obtained by the sol-gel method, and the surfaces of the carrier particles were deposited. Charge control particles for external addition for controlling the triboelectric charge amount of the electrostatic image developing toner composed of a charge control agent,
Charge control particles for external addition, comprising the charge control agent in a range of 1 × 10 ⁻³ to 1 × 10 ⁻¹ parts by mass with respect to 1 part by mass of the carrier particles. The hydrophobic spherical silica microparticles, tetrafunctional silane compound and / or R ² SiO its partial hydrolysis condensation product on the surface of the hydrophilic spherical silica microparticles composed of the obtained SiO ₂ units by hydrolysis and condensation _3/2 units (wherein R ² is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) and further R ¹ ₃ SiO _1/2 units (wherein R ¹ is a monovalent hydrocarbon group having 1 to 6 carbon atoms, which is the same or different, and is a hydrophobic spherical silica fine particle obtained by a hydrophobizing treatment into which R ¹ is introduced. Charge control particles for external addition. The hydrophobic spherical silica fine particles are
It is selected from silane compounds represented by the general formula (I): Si (OR ³ ) ₄ (wherein R ³ is the same or different and a monovalent hydrocarbon group having 1 to 6 carbon atoms) and hydrolysis condensates thereof. A step of obtaining a hydrophilic spherical silica fine particle dispersion by hydrolyzing and condensing one or more compounds in a mixed solution of a hydrophilic solvent, water, and a basic compound;
A step of adding water to the obtained hydrophilic spherical silica fine particle dispersion, distilling off the hydrophilic solvent to convert it into an aqueous dispersion, and completely hydrolyzing the alkoxy groups remaining on the surface of the fine particles;
In the hydrophilic spherical silica fine particle aqueous dispersion thus treated, the general formula (II): R ² Si (OR ⁴ ) ₃ (where R ² is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R ⁴ is a hydrophilic spherical silica to which one or two or more compounds selected from silane compounds represented by the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms and hydrolytic condensates thereof are added. Coating the surface of the fine particles to obtain hydrophobic spherical silica fine particles;
Adding a ketone solvent to the hydrophobic spherical silica fine particle aqueous dispersion and distilling off water to convert it into a hydrophobic spherical silica fine particle ketone solvent dispersion; and the hydrophobic spherical silica fine particle ketone solvent dispersion; Silazane compound represented by the general formula (III): R ¹ ₃ SiNHSiR ¹ ₃ (wherein R ¹ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms), and the general formula (IV): R ¹ ₃ SiX (where R ¹ is the same as in general formula (III), X is an OH group or a hydrolyzable group) is added and reacted to convert the silanol group remaining on the surface of the silica fine particles to a trialkylsilyl group. And further hydrophobizing;
The charge control particles for external addition according to claim 3 or 4, wherein the particles are hydrophobic spherical silica particles obtained by the above method.

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