JP2012101953A - Method for manufacturing deformed silica fine particle and toner external additive for developing electrostatic charge image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide deformed silica fine particle which is not spherical but deformed, which has high dispersibility and low cohesive property, and which is excellent in adhesiveness to toner and providing efficiency of flowability to toner and toner external additive for developing an electrostatic charge image comprising the deformed silica fine particle.SOLUTION: The method for producing the deformed silica fine particle has a step for generating nuclear particle of hydrophilic silica fine particle by hydrolyzing and condensing tetrafunctional silane compound represented by a general formula (1): Si(OR)or partially hydrolyzed and condensed product of the same in mixed medium of hydrophilic organic solvent and water in the presence of basic substance while reaction temperatures of each of steps are within the range of 40°C to 100°C, a step for adding deformation accelerating catalyst in the system, and a step for generating the deformed silica fine particle by adding the tetrafunctional silane compound represented by the general formula (1) or the partially hydrolyzed and condensed product of the same into the system.

Description

  The present invention relates to silica fine particles, and more particularly, to a method for producing irregularly shaped silica particles that can be suitably used as irregularly shaped silica particles and an external toner additive for developing electrostatic images.

  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 a copying operation using these developers, in order to have process compatibility, the developer needs to be excellent in fluidity, caking resistance, fixing properties, charging properties, cleaning properties, and the like. . In particular, inorganic fine particles are often added to the toner in order to improve fluidity, caking resistance, fixing properties, and cleaning properties.

  When the external additive and the toner are mixed on the toner surface using a mixer, it is necessary to adhere the external additive to the toner surface while unpacking the aggregate of the external additive. In some cases, the toner remains in a free state without adhering, or is adhering to some extent, but may be detached from the toner surface due to stress, rubbing, etc. in the developing device. It is often recognized that these free external additives migrate to the photoreceptor together with the toner when the toner is developed on the photoreceptor surface, remain on the photoreceptor surface after transfer, and adhere to the photoreceptor surface without being cleaned. It is done.

When these free external additives accumulate on the surface of the photoconductor, they often cause image quality defects on the copy (filming, etc.) or scratch the photoconductor surface. Is a cause of shortening. Another problem is that these free external additives spill from the developing machine during development and contaminate the copying machine. Alternatively, it may adhere to the carrier surface in the developer and inhibit charge transfer between the carrier and the toner, resulting in a factor that lowers the charge of the toner. Therefore, the adhesion of the external additive to the toner has been a problem.

  On the other hand, use of fumed silica as an inorganic external additive has been reported (for example, see Patent Document 1). However, fumed silica has a problem that its fluidity imparting effect to the toner is insufficient due to its complicated particle structure. It has also been reported that spherical fused silica is used as an external additive for toner (for example, see Patent Document 2). However, in this case as well, the adhesion to the surface of the toner resin particles is poor due to the spherical shape, and the surface of the toner particles from which the silica fine particles have dropped contacts the photoconductor surface of the copying machine, so that the toner is transferred to a predetermined paper. However, there is a problem that it tends to remain on the surface of the photoreceptor. Therefore, there has been a demand for the development of an external additive that improves the adhesion to the toner and the fluidity imparting effect to the toner while improving the fluidity, caking resistance, fixing property, and cleaning property.

JP 2002-116575 A JP 2002-154820 A

  The present invention has been made in order to solve the above-described problem, and is a non-spherical, irregularly shaped silica fine particle, particularly an irregularly shaped silica fine particle having high dispersibility and low cohesion, And a method for producing irregularly shaped silica fine particles having good fluidity imparting effect to the toner and maintaining the fluidity of the toner, and less dropping from the toner, and a toner external additive for developing electrostatic images comprising the irregularly shaped silica fine particles The purpose is to provide.

In order to solve the above problems, in the present invention,
A method for producing irregularly shaped silica fine particles having an average particle diameter of 5 to 500 nm,
The reaction temperature of each of the following steps is within the range of 40 ° C to 100 ° C,
(A) General formula (1): Si (OR ¹ ) ₄ (1)
[In the general formula (1), R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
At least one compound selected from the group consisting of a tetrafunctional silane compound represented by formula (II) and a partial hydrolysis-condensation product of the tetrafunctional silane compound, in the presence of a basic substance, Hydrolyzing and condensing in a mixed medium to produce core particles of hydrophilic silica fine particles,
(B) adding a heteromorphization promoting catalyst into the system;
(C) Subsequently, at least one compound selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound is further added to the system. And forming a hydrophilic silica fine particle by growing and deforming the core particle of the hydrophilic silica fine particle, and providing a method for producing the irregular silica fine particle.

  As described above, according to the method for producing irregularly shaped silica fine particles, it is possible to produce irregularly shaped silica fine particles that are not spherical, and in particular, irregularly shaped silica fine particles having high dispersibility and low agglomeration property, which adhere to the toner. This is a method for producing irregularly shaped silica fine particles that can produce irregularly shaped silica fine particles that have good properties and the effect of imparting fluidity to the toner, and that retain the fluidity of the toner and that are less likely to fall out of the toner.

  In addition, any of condensation catalysts, bifunctional compounds, and salts can be used as the catabolization promoting catalyst. Furthermore, it is preferable to use any one of Ti, Zr, Zn, and Al-based organometallic compound complexes as long as the condensation catalysts are used, and tetraalkylammonium hydroxide compounds are preferably used as the salts. Furthermore, if it is the said bifunctional compounds, it is preferable to use any of amino alcohols, diamines, and glycols.

  Thus, by using any of condensation catalysts, bifunctional compounds, and salts as the catabolization promoting catalyst, the average particle diameter is in the range of 5 to 500 nm, and the fibrous, columnar, and spheroids are used. It is possible to more efficiently obtain irregular shaped silica fine particles having a shape that is regarded as an irregular shape such as a shape, that is, a shape that is not considered spherical.

Further, as the hydrophilic organic solvent, the general formula ^{(2): R 2 OH (} 2)
[In general formula (2), it is preferable to use an alcohol solvent represented by R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms].

  As described above, by using the alcohol solvent represented by the general formula (2) as the hydrophilic organic solvent, the tetrafunctional silane compound represented by the general formula (1) in the steps (A) to (C) and At least one compound selected from the group consisting of partial hydrolysis-condensation products of the tetrafunctional silane compound and water can be dissolved satisfactorily, and the hydrolysis and condensation reaction can proceed favorably. Further, when the number of carbon atoms of the alcohol represented by the general formula (2) increases, the particle size of the deformed silica fine particles to be generated increases. Therefore, by selecting the type of alcohol represented by the general formula (2), the particle size of the target irregular shaped silica fine particles can be obtained.

  Furthermore, it is preferable to use ammonia as the basic substance.

  Thus, by using ammonia as the basic substance, the reaction conditions suitable for the hydrolysis and condensation reaction can be satisfied, and the hydrolysis and condensation reaction can proceed favorably.

In the present invention, in the method for producing irregularly shaped silica particles, after the step (C) of producing irregularly shaped silica particles,
(D) removing the hydrophilic organic solvent from the system and substituting the medium with water to obtain an aqueous dispersion of the hydrophilic deformed silica fine particles;
(E) R ³ SiO _3/2 unit on the surface of the hydrophilic deformed silica fine particles in the aqueous dispersion of the hydrophilic deformed silica fine particles [wherein R ³ is a substituted or unsubstituted carbon atom number of 1 to 20 Is a monovalent hydrocarbon group] to produce primary hydrophobic deformed silica fine particles,
(F) Furthermore, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same or different, substituted or unsubstituted, substituted or unsubstituted 1 to 6 carbon atoms on the surface of the primary hydrophobic irregularly shaped silica fine particles. And a step of producing secondary hydrophobic irregularly shaped silica particles by introducing a valent hydrocarbon group].

  Thus, according to the method for producing irregularly shaped silica fine particles, it is possible to produce irregularly shaped hydrophobic silica fine particles that are not spherical, and in particular, irregularly shaped silica fine particles having high dispersibility and low agglomeration properties. This is a method for producing irregularly shaped silica fine particles that can produce irregularly shaped silica fine particles that have good adhesion and fluidity imparting effects to the toner, and that retain the fluidity of the toner and that are less likely to fall out of the toner.

Furthermore, in the step (E), an aqueous dispersion of the hydrophilic irregular shaped silica fine particles is used.
Formula (3): R ³ Si (OR ⁴ ) ₃ (3)
[Wherein R ³ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms]
By adding a trifunctional silane compound represented by the formula, a partial hydrolysis condensation product of the trifunctional silane compound, or a mixture of the trifunctional silane compound and the partial hydrolysis condensation product, the hydrophilic property is increased. Preferably, R ³ SiO _3/2 units [wherein R ³ is the same as described above] are introduced into the surface of the irregular shaped silica fine particles to produce primary hydrophobic irregular shaped silica fine particles.

Thus, in the step (E), the aqueous dispersion of hydrophilic irregularly shaped silica particles is used.
A trifunctional silane compound represented by the general formula (3), a partial hydrolysis condensation product of the trifunctional silane compound, or a mixture of the trifunctional silane compound and the partial hydrolysis condensation product is added. Thus, R ³ SiO _3/2 units can be easily introduced onto the surface of the hydrophilic irregular shaped silica fine particles.

Further, in the step (F), the aqueous dispersion which is a dispersion medium of the primary hydrophobic irregular shaped silica fine particles is replaced with a ketone solvent to obtain a ketone solvent dispersion of the primary hydrophobic irregular shaped silica fine particles. In the ketone solvent dispersion of the primary hydrophobic irregular shaped silica fine particles, the general formula (4): R ⁵ ₃ SiNHSiR ⁵ ₃ (4)
[In General Formula (4), R ⁵ is the same or different, substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms]
A silazane compound represented by
General formula (5): R ⁵ ₃ SiX (5)
[In General Formula (5), R ⁵ is the same as above, and X is an OH group or a hydrolyzable group]
Or a mixture of the silazane compound and the monofunctional silane compound is added to triorganosilylate the reactive groups remaining on the surface of the primary hydrophobic deformed silica fine particles. Thus, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same as above] is introduced into the surface of the primary hydrophobic irregularly shaped silica fine particles to produce secondary hydrophobic irregularly shaped silica fine particles. It is preferable.

Thus, in the step (F), the aqueous dispersion which is the dispersion medium of the primary hydrophobic irregular shaped silica fine particles is replaced with a ketone solvent, and the ketone solvent dispersion of the primary hydrophobic irregular shaped silica fine particles is obtained. A silazane compound represented by the general formula (4), a monofunctional silane compound represented by the general formula (5), or the silazane compound in a ketone solvent dispersion of the primary hydrophobic irregular-shaped silica fine particles. And the monofunctional silane compound can be added to easily triorganosilylate the reactive groups remaining on the surface of the primary hydrophobic irregularly shaped silica fine particles. R ⁵ ₃ SiO _1/2 units can be introduced on the surface of the irregular shaped silica fine particles to produce secondary hydrophobic irregular shaped silica fine particles.

  Furthermore, the ketone solvent is preferably methyl isobutyl ketone.

  Thus, when the ketone solvent is methyl isobutyl ketone, the primary hydrophobic irregular shaped silica fine particles, the silazane compound represented by the general formula (4), and the monofunctionality represented by the general formula (5). The mixture of the silane compound, the silazane compound and the monofunctional silane compound, and the produced secondary hydrophobic irregular-shaped silica fine particles can be dissolved satisfactorily, and the hydrolysis and condensation reaction can proceed favorably.

  In addition, the present invention provides a toner external additive for developing an electrostatic charge image comprising hydrophobic irregularly shaped silica fine particles produced by the method for producing irregularly shaped silica fine particles.

  As described above, if the toner external additive for developing an electrostatic charge image is composed of hydrophobic irregular-shaped silica fine particles produced by the method for producing irregular-shaped silica fine particles, the toner fluidity, caking resistance, fixing property, and cleaning properties are improved. In addition to the general characteristics of external additives, it has good adhesion to toner and fluidity imparting effect to toner, and it is for electrostatic charge image development with less dropout from toner while maintaining toner fluidity Toner external additive. Therefore, high image quality can be expected by using the toner external additive for developing an electrostatic image of the present invention for developing an electrostatic image in electrophotography, electrostatic recording method or the like.

  As described above, irregularly shaped silica fine particles having high dispersibility and low agglomeration property, particularly hydrophobic irregularly shaped silica fine particles according to the present invention are useful as toner external additives and can improve toner fluidity. Further, since the particles are irregularly shaped particles having an irregular shape, they have high adhesion and are less likely to be detached and released from the toner surface, thereby suppressing the occurrence of image quality defects (filming, etc.) on the copy. it can. Therefore, high image quality can be expected by using the toner external additive for developing an electrostatic charge image composed of deformed silica fine particles, which can be produced according to the present invention, for developing an electrostatic charge image in an electrophotographic method or an electrostatic recording method. it can.

4 is an electron microscopic observation photograph of deformed silica fine particles obtained by the method for producing deformed silica fine particles of the present invention.

Hereinafter, the method for producing deformed silica fine particles and the toner external additive for developing an electrostatic charge image of the present invention will be described in detail, but the present invention is not limited thereto.
As described above, there has been a demand for the development of an external additive that has good fluidity, caking resistance, fixing property, cleaning property, etc., but has good adhesion to toner and fluidity imparting effect to toner. .

As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors set the reaction temperature in the following steps within the range of 40 ° C. to 100 ° C., and (A) General formula (1): Si (OR ¹ ) ₄ (1) [In the general formula (1), R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms] and the tetrafunctional silane compound Hydrophilic silica fine particles obtained by hydrolyzing and condensing at least one compound selected from the group consisting of partial hydrolysis-condensation products in a mixed medium of a hydrophilic organic solvent and water in the presence of a basic substance. (B) a step of adding a deforming promotion catalyst to the system, (C) a tetrafunctional silane compound represented by the general formula (1) and the tetrafunctional silane Selected from the group consisting of partially hydrolyzed condensation products of compounds And a step of adding at least one kind of compound to the system, and growing and deforming the hydrophilic silica fine particle core particles to produce hydrophilic deformed silica fine particles. The method for producing fine particles has found that irregular-shaped silica fine particles having an average particle diameter in the range of 5 to 500 nm can be produced, and the irregular-shaped fine silica particles, particularly hydrophobic irregular-shaped silica fine particles obtained by hydrophobizing the irregular-shaped silica fine particles. If it is useful as a toner external additive, the fluidity of the toner can be improved. Further, since the particles are irregularly shaped irregular particles, the adhesion is high and it is less likely to be detached from the toner surface and released. It has been found that it is possible to suppress the occurrence of image quality defects (filming, etc.) on a copy, and in addition, the deformed sheet that can be manufactured according to the present invention. The present invention has been completed by discovering that high image quality can be expected by using an external toner additive composed of Rica fine particles for development of an electrostatic charge image in electrophotography, electrostatic recording method or the like.

  Furthermore, the present inventors have provided the toner external additive for electrostatic charge image development comprising the hydrophobic irregularly shaped silica fine particles according to the present invention, such as fluidity to the developer, caking resistance, fixing property, and cleaning property. In addition to the desired properties of imparting, the particles are non-spherical irregularly shaped particles, so they are less likely to be detached and released from the toner surface, and do not cause image quality defects on the copy (filming, etc.) The inventors have found that high image quality can be achieved and completed the present invention.

<Conventional method for producing synthetic silica fine particles>
Synthetic silica fine particles are produced by combustion method silica obtained by burning a silane compound (that is, fumed silica), deflagration silica obtained by explosively burning metal silicon powder, sodium silicate and mineral acid. Wet silica obtained by the neutralization reaction of the above (the one synthesized under alkaline conditions is precipitated silica, the one synthesized under acidic conditions is gel silica), the sol-gel silica obtained by hydrolysis of hydrocarbyloxysilane (so-called (Stober method). Among these, the present invention relates to sol-gel silica, and is a method for producing irregular shaped silica fine particles by improving the sol-gel method.

<Characteristics of irregular shaped silica particles>
First, the characteristics of the irregular shaped silica fine particles according to the present invention will be described. FIG. 1 shows an electron microscopic observation photograph of deformed silica fine particles obtained by the method for producing deformed silica fine particles of the present invention. The irregular-shaped silica fine particles in the present invention have an average particle diameter in the range of 5 to 500 nm, and are regarded as irregular shapes such as fibrous shapes, columnar shapes, and spheroid shapes, that is, shapes that are not considered spherical. It is something to take. The minor axis / major axis ratio of the modified silica fine particles according to the present invention is preferably in the range of 0.01 to 0.8. When the minor axis / major axis ratio is within this range, a shape that is more regarded as a different shape, such as a fiber shape, a column shape, or a spheroid shape, that is, a shape that is not regarded as a spherical shape. In the case of the minor axis / major axis ratio in this range, it is preferable that the minor axis / major axis ratio is 0.8 or less because it is not too spherical. Further, it is preferable that the ratio of the minor axis / major axis is 0.01 or more because the production is easy. A more preferable range of the minor axis / major axis ratio is 0.1 to 0.7. Within this range, when applied to an external additive, it is less likely to be detached and released from the toner surface than conventionally known spherical silica, further suppressing the causes of image quality defects (filming, etc.) on the copy. it can.

<Measurement and calculation method of minor diameter / major diameter ratio of irregular shaped silica fine particles>
The measurement / calculation of the minor axis / major axis ratio was performed by the following method. First, in a photographic projection view obtained by taking a photograph of irregular-shaped silica fine particles with a scanning electron microscope at a magnification of 500,000 times (or 1,000,000 times), the maximum diameter of the particles is taken as the major axis, and the length is measured. The value was taken as the major axis (L). Next, a point that bisects the major axis on the major axis is determined, two points where a straight line perpendicular to the major axis intersects the outer edge of the particle are obtained, and the distance between the two points is measured to obtain a minor axis (S). . And it decided to calculate | require by calculating a short diameter / long diameter ratio (S / L) from these long diameters (L) and short diameters (S). This measurement was performed on any 50 particles, and the average value was defined as the minor axis / major axis ratio. When a plurality of major axes can be set for one particle, an average value of a plurality of corresponding minor axis lengths was obtained and used as the minor axis length (S).

<Ratio of irregular shaped silica fine particles (%)>
The proportion of irregularly shaped silica fine particles was measured by measuring the number of particles corresponding to the following (i) in the 50 particles to be measured for the short diameter / long diameter ratio in the above “Measurement method of short diameter / long diameter ratio”. , [(Number of (i) / 50) × 100] was defined as the ratio (%) of the number of deformed silica fine particles to the total number of silica fine particles.
(I) Particles having a minor axis / major axis ratio in the range of 0.01 to 0.8

  The proportion of the irregular shaped silica fine particles is preferably 50% or more, more preferably 70 to 100%. If this ratio is 50% or more, the ratio of detachment and separation from the toner surface when applied to an external additive is reduced, and the occurrence of image quality defects (filming, etc.) on the copy is suppressed. This is preferable because it is possible.

<Method for producing irregular shaped silica fine particles>
Next, the method for producing irregularly shaped silica particles of the present invention for producing the irregularly shaped silica particles will be described in detail. The present invention is a method for producing irregularly shaped silica fine particles having an average particle diameter in the range of 5 to 500 nm,
The reaction temperature of each of the following steps is within the range of 40 ° C to 100 ° C,
(A) General formula (1): Si (OR ¹ ) ₄ (1)
[In the general formula (1), R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
At least one compound selected from the group consisting of a tetrafunctional silane compound represented by formula (II) and a partial hydrolysis-condensation product of the tetrafunctional silane compound, in the presence of a basic substance, Hydrolyzing and condensing in a mixed medium to produce core particles of hydrophilic silica fine particles,
(B) adding a heteromorphization promoting catalyst into the system;
(C) Subsequently, at least one compound selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound is further added to the system. And forming a hydrophilic silica fine particle by growing and deforming the core particle of the hydrophilic silica fine particle.

<Reaction temperature>
First, the reaction temperature for performing the steps (A) to (C) is set between 40 and 100 ° C. When this reaction temperature is less than 40 ° C., spherical particles and associated particles are produced, and therefore it is difficult to synthesize target irregular-shaped silica fine particles. On the other hand, when the temperature is higher than 100 ° C., the water for hydrolysis volatilizes from the system, and the hydrolysis does not work as set, so that it is difficult to synthesize the desired modified silica fine particles. The reaction temperature is preferably 40 to 60 ° C.

  When core particles of hydrophilic silica fine particles are prepared at such a reaction temperature, core particles of hydrophilic silica fine particles having a relatively non-spherical shape are formed (step (A)). The particle size distribution is narrowed by adding a catabolization-promoting catalyst in step (B) to the system in which nuclei are formed, and by growing the core particles of the hydrophilic silica fine particles at the reaction temperature in step (C). It is possible to obtain the desired irregularly shaped silica fine particles that are not spherical. Hereinafter, each process will be described.

-Generation of core particles of hydrophilic silica fine particles (step (A))-
In this step, (A) general formula (1): Si (OR ¹ ) ₄ (1)
[In the general formula (1), R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
At least one compound selected from the group consisting of a tetrafunctional silane compound represented by formula (II) and a partial hydrolysis-condensation product of the tetrafunctional silane compound, in the presence of a basic substance, Hydrolysis and condensation in a mixed medium produce core particles of hydrophilic silica fine particles.

In the general formula (1), R ¹ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms, more preferably 1 to 4, more preferably 1 to 2 monovalent hydrocarbon group. is there. Examples of the monovalent hydrocarbon group represented by R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, and a phenyl group, preferably a methyl group, an ethyl group, a propyl group, and a butyl group, and particularly preferably , Methyl group, and ethyl group.

  Examples of the tetrafunctional silane compound represented by the general formula (1) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, tetraphenoxysilane, and the like. Silane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, particularly preferably tetramethoxysilane and tetraethoxysilane. Moreover, as a partial hydrolysis-condensation product of the tetrafunctional silane compound shown by General formula (1), these partial hydrolysis-condensation products, especially methyl silicate, ethyl silicate, etc. are mentioned, for example.

  The hydrophilic organic solvent is not particularly limited as long as it dissolves the tetrafunctional silane compound represented by the general formula (1), the partial hydrolysis-condensation product of the tetrafunctional silane compound, and water. E.g., alcohols, methyl cellosolve, ethyl cellosolve, buticellosolve, cellosolves such as cellosolve acetate, ketones such as acetone and methylethylketone, ethers such as dioxane and tetrahydrofuran, preferably alcohols, cellosolves, especially Preferably, alcohols are used.

As the alcohols,
Formula (2): R ² OH (2)
[In General Formula (2), R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
It is preferable to use the alcohol solvent shown by these.

In the general formula (2), R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1-2. Examples of the monovalent hydrocarbon group represented by R ² include an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, More preferably, a methyl group and an ethyl group are mentioned. Examples of the alcohol represented by the general formula (2) include methanol, ethanol, propanol, isopropanol, butanol and the like, preferably methanol and ethanol. As the number of carbon atoms in the alcohol increases, the particle size of the deformed silica fine particles produced increases. Therefore, it is desirable to select the type of alcohol according to the particle diameter of the target irregular shaped silica fine particles.

  Examples of the basic substance include ammonia and di-lower alkylamines such as dimethylamine and diethylamine, preferably ammonia and diethylamine, and particularly preferably ammonia. By using ammonia as the basic substance, the reaction conditions suitable for the hydrolysis and condensation reaction can be satisfied, and the hydrolysis and condensation reaction can proceed well. These basic substances may be dissolved in water in a required amount, and the obtained aqueous solution (basic) may be mixed with the hydrophilic organic solvent.

  In the hydrolysis reaction during the formation of the core particles of the hydrophilic silica fine particles in the step (A), the tetrafunctional silane compound represented by the general formula (1) and the partial hydrolysis condensation product of the tetrafunctional silane compound The amount of at least one compound selected from the group consisting of is preferably 0.3 to 15 mol%, more preferably based on the total amount used in the step (A) and the step (C). 0.5-7 mol%. If the amount used is 0.3 mol% or more, it is preferable because the particle group obtained by agglomerating the core particles of the hydrophilic silica fine particles can be prevented from becoming agglomerated. Moreover, if the usage-amount is 15 mol% or less, since the core particle of the said hydrophilic silica fine particle becomes large too much and it can suppress that it aggregates and settles, it is preferable.

  The amount of water used in the step (A) is at least 1 selected from the group consisting of a tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound. The amount is preferably 0.5 to 7 equivalents relative to the number of moles of alkoxy groups contained in the seed compound. The ratio of water and the hydrophilic organic solvent used in the step (A) is preferably 0.1 to 10 in terms of a weight ratio with the hydrophilic organic solvent being 1. Further, the amount of the basic substance is at least one compound selected from the group consisting of a tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis-condensation product of the tetrafunctional silane compound. It is preferable that it is 0.01-1 equivalent with respect to the number of moles of the alkoxy group contained in.

  Formation of core particles by hydrolysis and condensation of at least one compound selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound From the tetrafunctional silane compound represented by the general formula (1) and the partial hydrolysis-condensation product of the tetrafunctional silane compound in a mixed medium of the hydrophilic organic solvent containing the basic substance and water. It is carried out by adding at least one compound selected from the group consisting of:

-Step of adding a modification catalyst to the system (step (B))-
Step (B) is a step of adding a catalyst (catalyzing reforming catalyst) that promotes deforming into the system in which the core particles of the hydrophilic silica fine particles produced by (A) are present. . Condensation catalysts, bifunctional compounds, salts and the like are effective as a catalyst for promoting the modification of the silica fine particles. Thus, by using any of condensation catalysts, bifunctional compounds, and salts as the catabolism promoting catalyst, the average particle diameter is more efficiently in the range of 5 to 500 nm, and the fibrous, columnar, It is possible to obtain deformed silica fine particles having a shape that is regarded as a deformed shape such as a spheroid, that is, a shape that is not regarded as spherical.

  As the condensation catalysts, Ti, Zr, Zn, Al-based organometallic compound complexes are preferable, for example, titanium di-n-butoxide (bis 2,4-pentadionate), zirconium 2,4-pentadionate, Examples include zinc 2,4-pentadionate, aluminum (III) 2,4-pentadionate, or a mixture thereof. Moreover, what hydrolyzed these can also be used as a condensation catalyst.

  As the bifunctional compounds, amino alcohols, diamines, and glycols are preferable. Examples of the amino alcohols include monoethanolamine, isopropanolamine, 2-dimethylaminoethanol, 2-diethylaminoethanol, and mixtures thereof.

  Examples of the diamines include ethylene diamine, tetramethyl ethylene diamine, and mixtures thereof.

  Examples of the glycols include diethylene glycol, trimethylene glycol, tetramethylene glycol, 1,6-hexanediol, and mixtures thereof.

  The salt is preferably a tetraalkylammonium hydroxide, specifically selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or a mixture thereof. .

  By adding and interposing the deforming promotion catalyst, deforming of the core particles of the hydrophilic silica particles is promoted, and deformed silica particles are easily generated.

In the step (B), it is desirable to add 0.5 to 150 parts by mass of the modification catalyst for addition to 100 parts by mass of SiO _4/2 units contained in the core particles of the hydrophilic silica fine particles. More preferably, it is 2-80 mass parts. If this amount is 0.5 parts by mass or more, it is preferable because the deformation rate can be prevented from deteriorating. Moreover, if this amount is 150 parts by mass or less, it is preferable because aggregation of particles can occur or adverse effects on charging characteristics when used as an external additive can be suppressed.

-Process of growing and deforming particles (process (C))-
In the step (C), after adding the heteromorphization promoting catalyst to the system in the step (B), the tetrafunctional silane compound represented by the general formula (1) and the partial hydrolysis of the tetrafunctional silane compound are continued. In this step, at least one compound selected from the group consisting of condensation products is further added, and the core particles of the hydrophilic silica fine particles are grown and deformed to produce hydrophilic deformed silica fine particles.

  (C) In the hydrolysis reaction at the time of core particle growth / deformation of the hydrophilic silica fine particles in the step (C), the tetrafunctional silane compound represented by the general formula (1) and the partial hydrolytic condensation of the tetrafunctional silane compound The amount of at least one compound selected from the group consisting of products is preferably 99.7 to 85.0 mol%, more preferably, based on the total amount used in step (A) and step (C). Is 99.5-93.0 mol%.

  The amount of water used in the step (C) is at least one selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound. It is preferably 0.5 to 5 equivalents relative to the number of moles of alkoxy groups contained in the compound. Moreover, it is preferable that the ratio of the said water and the said hydrophilic organic solvent is 0.5-10 by weight ratio by making water into 1. Furthermore, the amount of the basic substance is included in at least one compound selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis-condensation product of the tetrafunctional silane compound. It is preferable that it is 0.01-2 equivalent with respect to the number-of-moles of the alkoxy group.

  The method of growing and deforming the core particles of the hydrophilic silica fine particles includes a tetrafunctional silane represented by the above general formula (1) in a mixture of a hydrophilic organic solvent containing a basic substance, water, and core particles. It is carried out by adding at least one compound selected from the group consisting of a compound and a partial hydrolysis-condensation product of the tetrafunctional silane compound, followed by hydrolysis and condensation.

  As described above, irregular silica fine particles having an average particle diameter in the range of 5 to 500 nm can be produced by performing the steps (A) to (C) with the reaction temperature in each step in the range of 40 to 100 ° C. As a result, irregularly shaped silica particles that are not spherical, particularly irregularly shaped silica particles having high dispersibility and low cohesiveness, are useful as toner external additives, and can improve the fluidity of the toner. Further, since the particles are irregularly shaped particles, they have high adhesion and are less likely to be detached and released from the toner surface, thereby suppressing image quality defects on the copy (filming, etc.). Deformed silica fine particles can be obtained.

Furthermore, after the step of producing the (C) deformed silica fine particles,
(D) removing the hydrophilic organic solvent from the system and substituting the medium with water to obtain an aqueous dispersion of the hydrophilic deformed silica fine particles;
(E) R ³ SiO _3/2 unit on the surface of the hydrophilic deformed silica fine particles in the aqueous dispersion of the hydrophilic deformed silica fine particles [wherein R ³ is a substituted or unsubstituted carbon atom number of 1 to 20 Is a monovalent hydrocarbon group] to produce primary hydrophobic deformed silica fine particles,
(F) Furthermore, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same or different, substituted or unsubstituted, substituted or unsubstituted 1 to 6 carbon atoms on the surface of the primary hydrophobic irregularly shaped silica fine particles. Is a hydrophobic hydrocarbon group, and is produced from the step of producing secondary hydrophobic irregularly shaped silica particles to produce hydrophobic irregularly shaped silica particles having particularly high dispersibility and low agglomeration. It is useful as an external toner additive, can improve the fluidity of the toner, and because the particles are irregularly shaped irregular particles, it has high adhesion and is less likely to be detached and released from the toner surface. Hydrophobic irregular-shaped silica fine particles that can further suppress the occurrence of image quality defects on copying (filming, etc.) can be generated. Hereinafter, each process of hydrophobization will be described in detail.

-Step of obtaining an aqueous dispersion of hydrophilic irregular shaped silica fine particles (step (D))-
In the step (D), the hydrophilic organic solvent is removed from the system in which the hydrophilic deformed silica fine particles generated in the step (C) are dispersed, the medium is replaced with water, and the hydrophilic deformed silica fine particles are dispersed in water. This is a step of obtaining a liquid. The operation of removing the hydrophilic organic solvent from the system and replacing the medium with water is, for example, an operation of adding water to the system and distilling off the hydrophilic organic solvent (repeat this operation as necessary). It can be carried out. The total amount of water added at this time is preferably on a mass basis with respect to the total amount of the hydrophilic organic solvent used in steps (A) and (C) and the amount of alcohol produced by the hydrolysis condensation reaction. Is more than twice the amount, more preferably 2.5 to 3.5 times the amount, particularly preferably 3 times the amount.

  The hydrophilic deformed silica fine particles in the aqueous dispersion thus obtained are subjected to a first-stage hydrophobization treatment in step (E).

  (D) It is preferable that content of the water of the aqueous dispersion obtained at a process is 90 mass% or more. If the content of water in the aqueous dispersion is 90% by mass or more, the amount of water in the aqueous dispersion is large. Therefore, in the subsequent step (E), hydrolysis of the hydrocarbyloxy group can be sufficiently advanced. This is preferable because the residual hydrocarbyloxy group content in the hydrophilic irregular-shaped silica fine particles is reduced.

-Surface hydrophobization treatment of hydrophilic irregular-shaped silica fine particles (step (E))-
The step (E) includes the step of _forming R ³ SiO _3/2 units on the surface of the hydrophilic deformed silica fine particles in the aqueous dispersion of the hydrophilic deformed silica fine particles, wherein R ³ is a substituted or unsubstituted carbon atom number. 1 to 20 monovalent hydrocarbon groups] are introduced to produce primary hydrophobic irregular-shaped silica fine particles. That is, it is a step of performing a first-stage hydrophobization treatment.

As a method for introducing R ³ SiO _3/2 units into the surface of the hydrophilic irregular shaped silica fine particles, for example, in an aqueous dispersion containing the hydrophilic irregular shaped silica fine particles and having a water content of 90% by mass or more,
Formula (3): R ³ Si (OR ⁴ ) ₃ (3)
[Wherein R ³ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms]
By adding a trifunctional silane compound represented by the formula, a partial hydrolysis condensation product of the trifunctional silane compound, or a mixture of the trifunctional silane compound and the partial hydrolysis condensation product, the hydrophilic property is increased. Examples thereof include a method of introducing R ³ SiO _3/2 units [wherein R ³ is the same as described above] onto the surface of the irregular shaped silica fine particles. Thereby, the surface of the hydrophilic irregular shaped silica fine particles can be treated to produce the first hydrophobic irregular shaped silica fine particles.

In the general formula (3), R ³ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, particularly preferably 1 to 4 monovalent hydrocarbon groups. It is a hydrocarbon group. Examples of the monovalent hydrocarbon group represented by R ³ include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, and a hexyl group, and a phenyl group. A methyl group, an ethyl group, an n-propyl group, and an isopropyl group, particularly preferably a methyl group and an ethyl group. Further, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom, preferably fluorine atom.

In the general formula (3), R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, particularly preferably 1 to 2 monovalent hydrocarbon groups. It is a group. Examples of the monovalent hydrocarbon group represented by R ⁴ include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group, preferably a methyl group, an ethyl group, and a propyl group, and particularly preferably a methyl group. Group and ethyl group.

  Examples of the trifunctional silane compound represented by the general formula (3) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, and n-propyltrimethoxysilane. Trialkoxysilane such as ethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, etc. Examples thereof include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane, and more preferably methyltrimethoxysilane and methyltrimethoxysilane. Tokishishiran and the like. Moreover, as a partial hydrolysis-condensation product of this trifunctional silane compound, these partial hydrolysis-condensation products are mentioned, for example.

The addition amount of the trifunctional silane compound represented by the general formula (3) is preferably 0.001 to 1 mol per 1 mol of SiO _4/2 units contained in the hydrophilic deformed silica fine particles contained in the aqueous dispersion. Is 0.01 to 0.1 mol, particularly preferably 0.01 to 0.05 mol.

-Surface triorganosilylation treatment of hydrophobic irregular shaped silica fine particles (step (F))-
(F) Furthermore, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same or different, substituted or unsubstituted, substituted or unsubstituted 1 to 6 carbon atoms on the surface of the primary hydrophobic irregularly shaped silica fine particles. This is a step of producing secondary hydrophobic irregularly shaped silica fine particles by introducing a valent hydrocarbon group]. That is, it is a step of performing the second stage hydrophobization treatment.

Examples of a method for introducing R ⁵ ₃ SiO _1/2 units into the surface of the primary hydrophobic irregularly shaped silica fine particles include, for example, an aqueous dispersion that is a dispersion medium for the primary hydrophobic irregularly shaped silica fine particles and a ketone solvent. To obtain a ketone-based solvent dispersion of primary hydrophobic irregular-shaped silica fine particles, and to the ketone-based solvent dispersion of primary hydrophobic irregular-shaped silica fine particles, a general formula (4): R ⁵ ₃ SiNHSiR ⁵ ₃ ( 4)
[In General Formula (4), R ⁵ is the same or different, substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms]
A silazane compound represented by
General formula (5): R ⁵ ₃ SiX (5)
[In General Formula (5), R ⁵ is the same as above, and X is an OH group or a hydrolyzable group]
Or a mixture of the silazane compound and the monofunctional silane compound is added to triorganosilylate the reactive groups remaining on the surface of the primary hydrophobic deformed silica fine particles. Thus, a method of introducing R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same as above] to the surface of the primary hydrophobic irregularly shaped silica fine particles can be mentioned. Thereby, secondary hydrophobic irregular shaped silica fine particles can be produced.

In the general formulas (4) and (5), R ⁵ is the same or different, substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, Preferably it is a 1-2 monovalent hydrocarbon group. Examples of the monovalent hydrocarbon group represented by R ⁵ include, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, preferably a methyl group, an ethyl group, and a propyl group. Includes a methyl group and an ethyl group. Further, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom, preferably fluorine atom.

  In the general formula (5), X represents an OH group or a hydrolyzable group, and examples of the hydrolyzable group represented by X include an alkoxy group such as a chlorine atom, a methoxy group, and an ethoxy group, an amino group, Examples include an acyloxy group such as an acetoxy group and a propionyloxy group, preferably an alkoxy group and an amino group, and particularly preferably an alkoxy group.

  The operation of replacing the aqueous dispersion, which is the dispersion medium of the primary hydrophobic irregularly shaped silica fine particles, with a ketone solvent is, for example, adding a ketone solvent to the aqueous dispersion and distilling off the water or the mixed solvent from the mixture. This operation can be performed (repeating this operation as necessary).

  The amount of the ketone solvent added at this time is preferably 0.5 to 5 times, more preferably 2 to 5 times, particularly preferably 3 with respect to the primary hydrophobic irregularly shaped silica fine particles. ~ 4 times the amount. Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, and acetyl acetone, and more preferably methyl isobutyl ketone.

  Examples of the silazane compound represented by the general formula (4) include hexamethyldisilazane and hexaethyldisilazane, and preferably hexamethyldisilazane. Examples of the monofunctional silane compound represented by the general formula (5) include monosilanol compounds such as trimethylsilanol and triethylsilanol, monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane, monomonosilanes such as trimethylmethoxysilane and trimethylethoxysilane. Examples include monoaminosilanes such as alkoxysilane, trimethylsilyldimethylamine and trimethylsilyldiethylamine, and monoacyloxysilanes such as trimethylacetoxysilane, preferably trimethylsilanol, trimethylmethoxysilane and trimethylsilyldiethylamine, particularly preferably trimethylsilanol and trimethylmethoxysilane. Can be mentioned.

The use amount of the above general formula (4) and the above general formula (5) is 0.05 to 0.00 per 1 mol of SiO ₂ unit contained in the first hydrophobic irregularly shaped silica fine particles in the ketone solvent. 5 mol, preferably 0.1 to 0.3 mol, particularly preferably 0.15 to 0.25 mol.

  The secondary hydrophobic irregularly shaped silica fine particles obtained in the step (F) may be obtained as a powder by a conventional method, or a silazane compound represented by the general formula (4) or the general formula (5). After the reaction between the monofunctional silane compound or the mixture of the silazane compound and the monofunctional silane compound, an organic compound may be added to obtain a dispersion.

  In addition, for example, when taking out irregular shaped silica particles for applications that do not require a high degree of hydrophobization treatment by the steps (D) to (F) as described above, it is generally known following the step (C). For example, a hydrophobizing treatment may be performed by adding a silylating agent, for example.

<Toner external additive comprising hydrophobic irregular shaped silica fine particles>
The irregular-shaped silica fine particles that can be produced according to the present invention, particularly the hydrophobic irregular-shaped silica fine particles produced by the steps (D) to (F) are suitable as toner external additives, particularly as toner external additives for developing electrostatic images. Can be used. The blending amount of the external toner additive for electrostatic image development comprising the hydrophobic irregularly shaped silica fine particles is usually 0.01 to 20 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner. Part by mass, particularly preferably 1 to 2 parts by mass. If the blending amount is 0.01 parts by mass or more, the adhesion amount to the toner is sufficient and sufficient fluidity is obtained, and if it is 20 parts by mass or less, the chargeability of the toner is adversely affected. Since it can suppress, it is preferable.

  The hydrophobic irregularly shaped silica fine particles may be adhered to the toner particle surface merely mechanically or loosely fixed. The adhered fine particles may cover the entire surface of the toner particles or only a part thereof. Further, the fine particles may partially form aggregates and cover the surface of the toner particles, but are preferably covered in the form of single-layer particles.

  Examples of the toner particles to which the modified silica fine particles that can be produced according to the present invention can be applied include known toner particles containing a binder resin and a colorant as main components, and if necessary, further charge control. An agent or the like may be added.

  The toner to which a toner external additive composed of deformed silica fine particles that can be produced according to the present invention is added is an electrostatic charge used for developing an electrostatic charge image by, for example, electrophotography or electrostatic recording. Used for image development and the like. The toner can be used as a one-component developer, but it can also be used as a two-component developer by mixing it with a carrier. When used as a two-component developer, the toner external coating 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, known ones, for example, ferrite, iron powder, etc., or those coated on the surface with resin can be used.

  The toner external additive comprising hydrophobic modified silica fine particles that can be produced according to the present invention has the general characteristics of an external additive that enhances the fluidity, caking resistance, fixability, and cleaning properties of the toner, and is particularly high. Dispersibility, low agglomeration, irregularly shaped particles, good adsorption to the toner surface, less detachment from the toner surface, and cause of image quality defects on the copy (filming, etc.) Therefore, the toner external additive enables high image quality.

  Hereinafter, the present invention will be described in more detail with reference to examples of the method for producing irregularly shaped silica fine particles of the present invention, and toner external additives for developing electrostatic images, and comparative examples, but the present invention is not limited thereto. is not.

[Synthesis of Hydrophobic Deformed Silica Fine Particles]
<Example 1>
In a 1 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 264 g of methanol, 10.7 g of water, and 13.5 g of 28% by mass ammonia water were mixed. This solution was adjusted to 45 ° C., 10 g (0.065 mol) of tetramethoxysilane and 10 g of 5.5 mass% ammonia water were simultaneously added while stirring, and both were added dropwise in 20 minutes. Thereafter, the mixture was stirred for 30 minutes while maintaining 45 ° C. to produce core particles. Thereto was added 0.49 g of a 20% aqueous methanol solution obtained by hydrolyzing titanium di-n-butoxide (bis 2,4-pentadionate) with an excess of ammonia water, as a catalyst for promoting modification of the shape. Thereafter, 205.5 g (1.35 mol) of tetramethoxysilane and 46.3 g of 5.5% by mass ammonia water were simultaneously added dropwise, and tetramethoxysilane and ammonia water were added dropwise over 3 hours. Even after the completion of the dropwise addition, the suspension was further stirred for 0.5 hour to carry out hydrolysis to obtain a suspension of hydrophilic irregularly shaped silica fine particles.

  Next, an ester adapter and a condenser tube were attached to the glass reactor, and the suspension was heated to 60 to 70 ° C. to distill off 330 g of methanol, and then 330 g of water was added. Subsequently, 100 g of methanol water was distilled off until the suspension reached 100 ° C., and 100 g of water was added three times. Further, 100 g of methanol water was distilled off to obtain an aqueous suspension of hydrophilic irregular shaped silica fine particles. To the obtained aqueous suspension, 2.1 g (0.015 mol) of methyltrimethoxysilane was added dropwise at room temperature over 0.5 hours, and stirring was continued for 12 hours after the addition. Thus, the surface of the silica fine particles was subjected to a first-stage hydrophobization treatment to obtain a first hydrophobic irregular shaped silica fine particle aqueous dispersion.

  After adding 270 g of methyl isobutyl ketone to the obtained dispersion, 540 g of water was distilled off over 5 hours by heating the dispersion to 80 to 110 ° C. After adding 45.6 g (0.28 mol) of hexamethyldisilazane to the obtained dispersion at room temperature, the dispersion is heated to 110 ° C. and reacted for 3 hours, whereby silica fine particles in the dispersion are obtained. Was trimethylsilylated. Next, the solvent in the dispersion was distilled off at 80 ° C. under reduced pressure (6650 Pa) to obtain 95.0 g of hydrophobic irregularly shaped silica fine particles as powder.

  The final hydrophobic irregular-shaped silica fine particles obtained were measured according to the following measurement methods. The obtained results are shown in Table 1.

Measurement method 1: Particle size measurement of hydrophobic irregular-shaped silica fine particles By adding the hydrophobic irregular-shaped silica fine particles obtained in Example 1 to methanol so as to be 0.5% by mass and applying ultrasonic waves for 10 minutes. The hydrophobic irregular shaped silica fine particles were dispersed. The particle size distribution of the hydrophobic irregularly shaped silica fine particles treated in this way was measured by a laser diffraction / scattering particle size distribution analyzer (trade name: LA910, manufactured by Horiba, Ltd.), and the volume-based median diameter was defined as the particle diameter. The median diameter is a particle diameter corresponding to 50% cumulative when the particle size distribution is expressed as a cumulative distribution.

Measurement method 2: Shape measurement of hydrophobic irregular-shaped silica fine particles Observation of hydrophobic irregular-shaped silica fine particles obtained in Example 1 with an electron microscope (manufactured by Hitachi, trade name: S-4700 type, magnification: 100,000 times) Performed and confirmed the shape.

Measurement method 3: Measurement / calculation of minor diameter / major diameter ratio of irregular shaped silica fine particles Measurement / calculation of minor diameter / major diameter ratio was performed by the following method. First, in the photograph projection drawing obtained by photographing the hydrophobic irregularly shaped silica fine particles obtained in Example 1 with a scanning electron microscope at a magnification of 500,000 times (or 1,000,000 times), the maximum diameter of the particles is defined as the major axis. The length was measured, and the value was defined as the major axis (L). Next, a point that bisects the major axis on the major axis is determined, two points where a straight line perpendicular to the major axis intersects the outer edge of the particle are obtained, and the distance between the two points is measured to obtain the minor axis (S) did. And it calculated | required by calculating a short diameter / long diameter ratio (S / L) from these long diameters (L) and short diameters (S). This measurement was performed on any 50 particles, and the average value was defined as the minor axis / major axis ratio. When a plurality of major axes can be set for one particle, an average value of a plurality of corresponding minor axis lengths was obtained and used as the minor axis length (S).

Measurement method 4: Measurement of the ratio of irregular-shaped silica fine particles The ratio of irregular-shaped silica fine particles was measured by measuring 50 short-axis / major-axis ratios in “Measurement method of minor axis / major axis ratio” of measurement method 3. In the particles, the number of particles corresponding to the following (i) was measured, and the value of (number of (i) / 50) × 100 was defined as the ratio (%) of deformed silica fine particles to the total number of silica fine particles.
(I) Particles having a minor axis / major axis ratio in the range of 0.01 to 0.8

[Preparation of external additive mixed toner]
By melt-kneading, pulverizing and classifying 96 parts by mass of a polyester resin having a glass transition temperature Tg of 60 ° C. and a softening point of 110 ° C. and 4 parts by mass of a colorant (manufactured by Sumitomo Color Co., Ltd., trade name: Carmine 6BC) A toner having an average particle diameter of 7 μm was obtained. 40 g of this toner was mixed with 1 g of the hydrophobic irregularly shaped silica fine particles obtained in Example 1 by a sample mill to obtain an external additive mixed toner. Using this, the toner fluidity was measured according to the following measurement method 5. The results obtained are shown in Table 2.

Measurement method 5: Measurement of toner fluidity The toner fluidity was measured using a powder fluidity analyzer FT-4 (manufactured by Sysmex Corporation). The measurement principle of this apparatus will be described. A cylindrical container placed vertically is filled with powder, and while rotating two rotating blades (blades) provided at the tip of a vertical shaft rod in the powder, a certain distance (from height H1) Down to H2. The force received from the powder at this time is measured separately for the torque component and the load component, so that each work (energy) associated with the blade descending from H1 to H2 is obtained, and then the total energy amount of both Ask for. The smaller the total energy amount measured in this way, the better the fluidity of the powder, so it can be used as an index of powder fluidity.

  The fluidity of the toner was subjected to a stability test, a flow rate test, an aeration test, and a compression test having different measurement conditions, which will be described in detail below, in accordance with the above measurement principle. As will be described below, the container and blade to be used are properly used according to each test.

container:
In the stability, flow rate and ventilation tests, a glass cylindrical container having a volume of 120 ml, an inner diameter of 80 mm, and a length of 60 mm was used. In the compression test, a glass cylindrical container having a volume of 25 ml, an inner diameter of 25 mm, and a length of 52.5 mm was used. It is comprised so that air can be introduce | transduced from the lower part of a container.

blade:
Two stainless steel shaft rods are vertically mounted in the center of the cylindrical container so as to be horizontally opposed to each other. A blade with a diameter of 48 mm is used for a container with a volume of 120 ml, and a blade with a diameter of 23.5 ml is used for a container with a volume of 25 ml.

  Length from H1 to H2: 50 mm for a container with a volume of 120 ml and 47.5 mm for a container with a volume of 25 ml.

Stability test:
As described above, the powder flow characteristics when the powder filled in the measurement container is caused to flow from a stationary state are observed. The total energy amount is measured seven times continuously under the condition that the rotational speed of the blade tip is 100 mm / sec. Table 2 shows the total amount of energy for the seventh time (referred to as basic fluidity energy because it is the most stable state). The smaller the value, the higher the stability.

Flow rate test:
The powder flow characteristics with respect to the change of flow velocity are observed. Table 2 shows the total energy amount when the rotational speed of the blade tip was measured at 10 mm / sec. The smaller the value, the higher the fluidity.

Ventilation test:
Check the powder flow characteristics according to the air flow rate. The rotational speed of the blade tip is set to 100 mm / sec, the amount of air introduced from the lower part of the container is increased in steps of 0.1 mm / sec from 0 mm / sec, and measured separately in six steps from 0.5 mm / sec. Table 2 shows the total energy amount at the minimum air flow rate (0 mm / sec) and the maximum air flow rate (0.5 mm / sec). The smaller the value, the higher the powder fluidity when air is involved.

Compression test:
The powder flow characteristics with respect to compression are observed. After applying a weight to the powder through a piston and compressing it by applying pressure at 10 N, the rotational speed of the blade tip was measured at 100 mm / sec to obtain the total energy amount. The results are shown in Table 2. The smaller the powder, the higher the powder fluidity when the powder is compressed.

[Developer preparation]
5 parts by weight of the external additive mixed toner prepared above and 95 parts by weight of a carrier coated with a polymer obtained by polyblending a perfluoroalkyl acrylate resin and an acrylic resin on a ferrite core having an average particle diameter of 85 μm are mixed together to prepare a developer. Was prepared. Using this developer, the toner charge amount was measured according to the following measurement method 6, toner adhesion to the photoreceptor was measured according to measurement method 7, and cleaning property was judged according to measurement method 8. The results obtained are shown in Table 2.

Measurement method 6: Measurement of toner charge amount The developer was left for 1 day under conditions of high temperature and high humidity (30 ° C., 90% RH (relative humidity)) or low temperature and low humidity (10 ° C., 15% RH). The mixture was mixed for 30 seconds with a shaker to perform tribocharging. The charge amount of each sample was measured using a blow-off powder charge amount measuring device (trade name: TB-200, manufactured by Toshiba Chemical Corporation) under the same conditions. By determining the difference in toner charge amount under the above two conditions, the environmental dependency of the toner was evaluated.

Measurement method 7: Measurement of toner adhesion to the photoconductor The above developer was placed in a two-component modified developer equipped with an organic photoconductor, and a print test of 30000 sheets was performed. The adhesion of toner to the photoreceptor can be detected as white spots in all solid images. The degree of white spots was evaluated according to the following criteria.
White spots more than 10 / cm ^2: many white spots 1 to 9 / cm ^2: little white spots 0 / cm ^2: None

Measurement method 8: Cleaning property For the evaluation of cleaning property, after completion of the evaluation of the actual machine, scratches on the surface of the latent image carrier and the state of sticking of residual toner and the influence on the output image were visually evaluated.
A: Not generated.
○: Slight scratches are observed, but there is no effect on the image.
Δ: Residual toner and scratches are observed, but the influence on the image is small.
×: Residual toner is considerably large, and vertical stripe-like image defects occur.
× ×: Residual toner adheres and many image defects occur.

<Example 2>
93.5 g of hydrophobic irregularly shaped silica fine particles were obtained as a dry powder in the same manner as in Example 1 except that the reaction temperature in steps (A) to (C) was 55 ° C. Measurement was performed in the same manner as in Example 1 using the hydrophobic irregularly shaped silica fine particles. The results are shown in Tables 1 and 2.

<Example 3>
Titanium chelate hydrolyzate (20% methanol aqueous solution of titanium di-n-butoxide (bis-2,4-pentadionate) hydrolyzed with excess ammonia water) used in Example 1 as a catabolism promoting catalyst. 95.5 g of hydrophobic irregularly shaped silica fine particles were obtained as a dry powder in the same manner except that 1.95 g (0.001 mol) of a 20% aqueous solution of tetramethylammonium hydroxide was used. Measurement was performed in the same manner as in Example 1 using the hydrophobic irregularly shaped silica fine particles. The results are shown in Tables 1 and 2.

<Example 4>
Titanium chelate hydrolyzate (20% methanol aqueous solution of titanium di-n-butoxide (bis-2,4-pentadionate) hydrolyzed with excess ammonia water) used in Example 1 as a catabolism promoting catalyst. 96.0 g of hydrophobic irregularly shaped silica fine particles were obtained as a dry powder in the same manner except that 0.20 g (0.003 mol) of ethylenediamine was used and the reaction temperature in steps (A) to (C) was 60 ° C. . Measurement was performed in the same manner as in Example 1 using the hydrophobic irregularly shaped silica fine particles. The results are shown in Tables 1 and 2.

<Comparative Example 1>
94.8 g of hydrophobic silica fine particles were obtained as a dry powder in the same manner as in Example 1, except that the catalyst for promoting modification was not used. Measurement was performed in the same manner as in Example 1 using the hydrophobic silica fine particles. The results are shown in Tables 1 and 2.

<Comparative example 2>
95.1 g of hydrophobic silica fine particles were obtained as a dry powder in the same manner as in Example 1 except that the reaction temperature in steps (A) to (C) was 35 ° C. Measurement was performed in the same manner as in Example 1 using the hydrophobic silica fine particles. The results are shown in Tables 1 and 2.

<Comparative Example 3>
In a 1 liter glass reactor equipped with a stirrer, a dropping funnel, and a thermometer, 264 g of methanol, 13.5 g of water, and 13.5 g of 28% by mass ammonia water were mixed. The solution was adjusted to 45 ° C., and 215.5 g (1.42 mol) of tetramethoxysilane and 53.6 g of 5.5 mass% ammonia water were simultaneously added while stirring, and tetramethoxysilane and ammonia water were added. Each was added dropwise over 4 hours. Even after the completion of the dropwise addition, the suspension was further stirred for 0.5 hours to carry out hydrolysis to obtain a suspension of hydrophilic silica fine particles. Next, an ester adapter and a condenser tube were attached to the glass reactor, and the suspension was heated to 60 to 70 ° C. to distill off 330 g of methanol, and then 330 g of water was added. Subsequently, 100 g of methanol water was distilled off until the suspension reached 100 ° C., and 100 g of water was added three times. Further, 100 g of methanol water was distilled off to obtain an aqueous suspension of hydrophilic silica fine particles.

To the obtained aqueous suspension, 2.1 g (0.015 mol) of methyltrimethoxysilane was added dropwise at room temperature over 0.5 hours, and stirring was continued for 12 hours after the addition. Thus, the first hydrophobic silica fine particle aqueous dispersion was obtained by subjecting the silica fine particle surface to the first-stage hydrophobization treatment.
After adding 270 g of methyl isobutyl ketone to the obtained dispersion, 540 g of water was distilled off over 5 hours by heating the dispersion to 80 to 110 ° C. After adding 45.6 g (0.28 mol) of hexamethyldisilazane to the obtained dispersion at room temperature, the dispersion is heated to 110 ° C. and reacted for 3 hours, whereby silica fine particles in the dispersion are obtained. Was trimethylsilylated. Subsequently, the solvent in this dispersion was distilled off at 80 ° C. under reduced pressure (6650 Pa) to obtain 96.3 g of hydrophobic silica fine particles as a powder. Evaluation was performed in the same manner as in Example 1 using the hydrophobic silica fine particles. The results are shown in Tables 1 and 2.

（１）７回目
（２）ブレードスピード １０ｍｍ／ｓ
（３）通気量 ０ｍｍ／ｓ
（４）通気量 ０．５ｍｍ／ｓ
（５）加圧 １０Ｎ

(1) 7th time (2) Blade speed 10mm / s
(3) Aeration rate 0mm / s
(4) Aeration rate 0.5mm / s
(5) Pressure 10N

  As shown in Comparative Example 1 in which the step (B) of the present invention is not performed, Comparative Example 2 in which the reaction temperature is not in the range of 40 to 100 ° C., and Comparative Example 3 in which the step (B) and the step (C) are not performed, It was revealed that the silica fine particles produced in these comparative examples were not deformed silica fine particles (Table 1). In addition, the silica fine particles obtained in Comparative Examples 1 to 3 were found to be inferior in powder flowability in the stability test, flow rate test, aeration test, and compression test. It was shown that the toner adhesion was poor because there were many white spots, and the cleaning ability was also poor (Table 2). In particular, in Comparative Examples 1 and 3 in which the step (B) is not performed, it became clear that the toner adhesion and the cleaning properties deteriorate. Further, in Comparative Example 2 where the reaction temperature was not in the range of 40 to 100 ° C., the results of the aeration test were remarkably bad. On the other hand, as shown in the examples, the deformed silica fine particles produced by the steps (A) to (F) of the present invention are excellent in powder flowability in the stability test, flow rate test, aeration test, and compression test, It was revealed that there was almost no difference in toner charge amount depending on the environment, and the toner adhesion and cleaning properties were excellent.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Claims (12)

A method for producing irregularly shaped silica fine particles having an average particle diameter of 5 to 500 nm,
The reaction temperature of each of the following steps is within the range of 40 ° C to 100 ° C,
(A) General formula (1): Si (OR ¹ ) ₄ (1)
[In the general formula (1), R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
At least one compound selected from the group consisting of a tetrafunctional silane compound represented by formula (II) and a partial hydrolysis-condensation product of the tetrafunctional silane compound, in the presence of a basic substance, Hydrolyzing and condensing in a mixed medium to produce core particles of hydrophilic silica fine particles,
(B) adding a heteromorphization promoting catalyst into the system;
(C) Subsequently, at least one compound selected from the group consisting of the tetrafunctional silane compound represented by the general formula (1) and a partial hydrolysis condensation product of the tetrafunctional silane compound is further added to the system. And forming the hydrophilic silica fine particles by growing and deforming the core particles of the hydrophilic silica fine particles, and producing the deformed silica fine particles.   2. The method for producing deformed silica fine particles according to claim 1, wherein any one of a condensation catalyst, a bifunctional compound, and a salt is used as the deforming promotion catalyst.   3. The method for producing irregularly shaped silica particles according to claim 2, wherein any one of Ti, Zr, Zn, and Al-based organometallic compound complexes is used as the condensation catalyst.   The method for producing deformed silica fine particles according to claim 2, wherein a tetraalkylammonium hydroxide compound is used as the salt.   The method for producing deformed silica fine particles according to claim 2, wherein any one of amino alcohols, diamines, and glycols is used as the bifunctional compounds. As the hydrophilic organic solvent,
Formula (2): R ² OH (2)
[In General Formula (2), R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms]
6. The method for producing deformed silica fine particles according to any one of claims 1 to 5, wherein an alcohol solvent represented by the formula (1) is used.   The method for producing deformed silica fine particles according to any one of claims 1 to 6, wherein ammonia is used as the basic substance. In the method for producing deformed silica fine particles according to any one of claims 1 to 7, after the step of generating the (C) deformed silica fine particles,
(D) removing the hydrophilic organic solvent from the system and substituting the medium with water to obtain an aqueous dispersion of the hydrophilic deformed silica fine particles;
(E) R ³ SiO _3/2 unit on the surface of the hydrophilic deformed silica fine particles in the aqueous dispersion of the hydrophilic deformed silica fine particles [wherein R ³ is a substituted or unsubstituted carbon atom number of 1 to 20 Is a monovalent hydrocarbon group] to produce primary hydrophobic deformed silica fine particles,
(F) Furthermore, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same or different, substituted or unsubstituted, substituted or unsubstituted 1 to 6 carbon atoms on the surface of the primary hydrophobic irregularly shaped silica fine particles. And a step of producing secondary hydrophobic irregularly shaped silica fine particles by introducing a valent hydrocarbon group]. In the step (E), in the aqueous dispersion of the hydrophilic irregularly shaped silica fine particles,
Formula (3): R ³ Si (OR ⁴ ) ₃ (3)
[Wherein R ³ is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ⁴ is the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms]
By adding a trifunctional silane compound represented by the formula, a partial hydrolysis condensation product of the trifunctional silane compound, or a mixture of the trifunctional silane compound and the partial hydrolysis condensation product, the hydrophilic property is increased. 9. The first hydrophobic irregular-shaped silica fine particles are produced by introducing R ³ SiO _3/2 units [wherein R ³ is the same as above] into the surface of the irregular-shaped silica fine particles. The manufacturing method of the unusual shape silica fine particle of description. In the step (F), the aqueous dispersion that is the dispersion medium of the primary hydrophobic irregular-shaped silica fine particles is replaced with a ketone solvent to obtain a ketone-based solvent dispersion of the primary hydrophobic irregular-shaped silica fine particles, Formula (4): R ⁵ ₃ SiNHSiR ⁵ ₃ (4)
[In General Formula (4), R ⁵ is the same or different, substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms]
A silazane compound represented by
General formula (5): R ⁵ ₃ SiX (5)
[In General Formula (5), R ⁵ is the same as above, and X is an OH group or a hydrolyzable group]
Or a mixture of the silazane compound and the monofunctional silane compound is added to triorganosilylate the reactive groups remaining on the surface of the primary hydrophobic deformed silica fine particles. Thus, R ⁵ ₃ SiO _1/2 unit [wherein R ⁵ is the same as above] is introduced into the surface of the primary hydrophobic irregularly shaped silica fine particles to produce secondary hydrophobic irregularly shaped silica fine particles. The method for producing irregularly shaped silica fine particles according to claim 8 or 9, wherein:   The method for producing fine-shaped silica fine particles according to claim 10, wherein the ketone solvent is methyl isobutyl ketone.   12. A toner external additive for developing an electrostatic charge image, comprising hydrophobic irregular-shaped silica fine particles produced by the method for producing irregular-shaped silica fine particles according to any one of claims 8 to 11.

Images