JP3856744B2 - Toner external additive for electrostatic image development - Google Patents

Description

注：MIBK:メチルイソブチルケトン、THF:テトラヒドロフラン、D₅:デカメチルシクロペンタシロキサン
処理剤A：イソプロピルトリイソステアロイルチタネート
処理剤B：イソプロポキシチタントリ(ジオクチルピロホスフェート)
【００６２】
【表２】

【００６３】
【発明の効果】
本発明の静電荷像現像用トナー外添剤により、現像剤の流動性、耐ケーキング性、定着性、クリーニング性を高めるばかりでなく、感光体の変質や削れおよび感光体へのトナー付着が生じず、また、環境状態に影響されない帯電性を付与するといった効果が得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner external additive for developing an electrostatic charge image used for developing an electrostatic charge image in electrophotography, electrostatic recording method or the like. The present invention relates to an external additive for a small particle size toner used for high image quality.
[0002]
[Prior art]
Dry developers used in electrophotography and the like can be broadly 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 the toner is mixed with a carrier, and 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, an inorganic fine powder is often added to the toner in order to improve fluidity, caking resistance, fixability, and cleaning properties.
[0003]
However, the inorganic fine powder has a great influence on charging. For example, generally used silica-based fine powder has strong negative polarity, and excessively increases the chargeability of the negatively chargeable toner particularly under low temperature and low humidity, while taking in moisture under high temperature and high humidity. In order to reduce the charging property, there is a problem that a large difference is caused between the charging properties of the two. As a result, density reproduction failure and background fogging may occur. In addition, the dispersibility of the inorganic fine powder also has a great influence on the toner characteristics, and if the dispersibility is not uniform, desired characteristics cannot be obtained in fluidity and caking resistance, or cleaning becomes insufficient. Toner sticking or the like may occur on the photoreceptor, which may cause black spot image defects.
[0004]
In order to improve these points, various proposals have been made to use a surface-treated inorganic fine powder. For example, JP-A-46-5782, JP-A-48-47345, and JP-A-48-47346 describe hydrophobizing the surface of silica fine powder. However, sufficient effects cannot always be obtained by using these inorganic fine powders.
[0005]
JP-A-49-42354 and JP-A-55-26518 describe that silica powder is treated with silicone oil. However, the toner to which the surface-treated silica is added has a problem that the offset resistance is lowered, and the toner adheres to the heating roll and stains the next copy. This occurs because, when the wax added to impart releasability to the toner and the silicone oil-treated silica fine powder are mixed, the wax thickens and inhibits the release effect.
[0006]
Further, as a method for alleviating the strong negative chargeability of the silica fine powder, a method in which the silica fine powder is surface-treated with an amino-modified silicone oil (Japanese Patent Laid-Open No. 64-73354), and the silica fine powder is treated with aminosilane and / or amino Surface treatment with modified silicone oil (JP-A-237561), surface treatment of silica fine powder with quaternary ammonium salt (JP-A-5-100471), silica fine powder surface with amphoteric surfactant A processing method (JP-A-6-95426) is known. However, treatment with these compounds can suppress an excessive charge increase of the negatively chargeable toner, but cannot sufficiently improve the environmental dependency of the silica fine powder itself. In other words, it is possible to slightly suppress the excessive negative chargeability of silica fine powder that occurs after long-term use under low temperature and low humidity, but similar charge suppression occurs when used for a long time under high temperature and high humidity. End up. In this way, the environment dependency is not improved as usual. Further, when silicone oil is used as the treating agent, the viscosity thereof is high, so that silica is agglomerated at the time of treatment, and there is a disadvantage that powder fluidity is deteriorated.
[0007]
As another method of reducing the charging environment dependency of the silica fine powder, there is a method of surface treatment with a titanate coupling agent (Japanese Patent No. 3028862, Japanese Patent Laid-Open No. 5-224456, Japanese Patent Laid-Open No. 9-297426). Are known. However, since the base silica fine powder used in these is a non-uniform aggregate in which primary particles are strongly aggregated, it is difficult to hold such an aggregate on the toner surface. When detached, the charge imparting member and the like are contaminated and the durability is adversely affected, and the toner dispersibility is also adversely affected. In addition, even if the surface treatment with a titanate coupling agent can reduce the dependence on the charging environment, the surface treatment is likely to be non-uniform in the aggregate, and non-uniformity in chargeability is likely to occur. There is.
[0008]
Further, when an organic photoreceptor is used for higher image quality or a toner having a smaller particle diameter is used, sufficient performance cannot be obtained with the above-mentioned inorganic fine powder. Organic photoreceptors tend to have a shorter life because their surfaces are softer and more reactive than inorganic photoreceptors. Therefore, when such an organic photoreceptor is used, the photoreceptor is easily altered or scraped by the inorganic fine powder added to the toner. In addition, when the toner has a small particle size, the powder fluidity is poor compared to a toner having a normal particle size, so a large amount of inorganic fine powder must be added and used. Inorganic fine powder may cause toner adhesion to the photoreceptor.
[0009]
[Problems to be solved by the invention]
The problem of the present invention is that there is no reaction or interaction with the organophotoreceptor so that it does not cause deterioration or abrasion of the organophotoreceptor, and because the fluidity is good, no toner adheres to the photoreceptor. Another object of the present invention is to provide an external additive for toner composed of silica fine particles having charging properties that are not affected by environmental conditions.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have satisfied the following conditions (i) and (ii), and spherical hydrophobic silica fine particles having an average primary particle diameter of 0.01 to 5 μm It has been found that an external toner additive for developing electrostatic images, characterized by comprising silica fine particles processed with a titanate coupling agent, solves this problem.
[0011]
(i) When an organic compound that is liquid at room temperature and has a dielectric constant of 1 to 40 F / m and silica fine particles are mixed and shaken at a weight ratio of 5: 1, the silica fine particles are contained in the organic compound. Disperse uniformly.
[0012]
(ii) The initial presence of primary particles remaining as primary particles when methanol is distilled off from a dispersion in which the silica fine particles are dispersed in methanol under heating and then kept at a temperature of 100 ° C. for 2 hours. The ratio to the primary particle amount is 20% or more.
[0013]
In addition, the hydrophobic silica-based fine particles used in the present invention have a highly hydrophobic surface, almost no reactive groups such as silanol groups remain, and further have high dispersibility, low agglomeration, and good fluidity. It is optimal as a base silica fine particle and gives good results for the purpose of the present invention. In addition, it is guessed that a titanate coupling agent reacts with the silanol group which remained slightly on the hydrophobic silica fine particle, or is hold | maintained at the silica fine particle by adsorption | suction.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hydrophobic silica fine particles used in the present invention are SiO₂R on the surface of hydrophilic silica particles consisting of units²Si0_3/2Unit (however, R²Is substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms).¹ _ThreeSiO_1/2Unit (however, R¹Are spherical hydrophobic silica fine particles having an average particle diameter of 0.01 to 5 μm obtained by introducing the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms. .
[0015]
An example of the method for producing the hydrophobic silica fine particles is as follows.
Formula (I): Si (OR^Three)_Four(However, R^ThreeIs a tetrafunctional silane compound represented by the same or different monovalent hydrocarbon group having 1 to 6 carbon atoms) or one or more compounds selected from the hydrolyzate thereof, and hydrophilic such as methanol and ethanol. A step of obtaining a hydrophilic silica fine particle dispersion by hydrolysis and condensation in a mixed solution of a basic solvent such as a basic solvent, water and ammonia or organic amine; water is added to the obtained hydrophilic silica fine particle dispersion; A step of distilling off the hydrophilic solvent and converting it to an aqueous dispersion to completely hydrolyze the alkoxy groups remaining on the surface of the fine particles; the hydrophilic silica fine particle aqueous dispersion treated in this way is represented by the general formula (II): R²Si (OR^Four)_Three(However, R²Is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R^FourIs a hydrophilic silica obtained by adding one or more compounds selected from trifunctional silane compounds represented by the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms and hydrolytic condensates thereof. A step of treating the surface of the fine particles to obtain hydrophobic silica fine particles (hereinafter sometimes referred to as “intermediate hydrophobic silica fine particles”); adding a ketone solvent to the aqueous dispersion of hydrophobic silica fine particles and distilling off the water A step of converting to a hydrophobic silica fine particle ketone solvent dispersion; and the hydrophobic silica fine particle ketone solvent dispersion to the general formula (III): R¹ _ThreeSiNHSiR¹ _Three(However, R¹Are the same or different monovalent hydrocarbon groups having 1 to 6 carbon atoms), and the general formula (IV): R¹ _ThreeSiX (however, R¹Is the same as in general formula (III). By adding a compound selected from monofunctional silane compounds represented by X (OH group or hydrolyzable group) and reacting it, the silanol group remaining on the surface of the silica fine particles is trialkylsilylated and further hydrophobized. can get. (In the following, the thus obtained product may be referred to as “final hydrophobic silica fine particles”.)
[0016]
Specific examples of the tetrafunctional silane compound represented by the general formula (I) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Specific examples of the partial hydrolysis condensate of the tetrafunctional silane compound represented by the general formula (I) include methyl silicate, ethyl silicate and the like.
[0017]
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, alcohols, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolves such as cellosolve acetate , Ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and tetrahydrofuran, and the like, preferably alcohols. As alcohols, general formula (V): R⁶0H (However, R⁶Is a monovalent hydrocarbon group having 1 to 6 carbon atoms), and specific examples include methanol, ethanol, isopropanol, butanol and the like. 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.
[0018]
Moreover, as said basic compound, ammonia, dimethylamine, diethylamine etc. are mentioned, Preferably it is ammonia. These basic compounds may be dissolved in water in a required amount, and the obtained basic aqueous solution may be mixed with a hydrophilic organic solvent.
[0019]
The amount of water used at this time is preferably 0.5 to 5 mol per mol of the alkoxy group contained in the silane compound of the general formula (I) or its partial hydrolysis-condensation product. The ratio is preferably 0.5 to 10 by weight, and the amount of the basic compound is 0.01 to 1 mol per mol of the alkoxy group contained in the silane compound of the general formula (I) or its partial hydrolysis condensate. Is preferred.
[0020]
Hydrolysis and condensation of a tetrafunctional silane compound of the general formula (I) is a well-known method in which a tetrafunctional silane compound of the general formula (I) is dropped into a mixture of a hydrophilic organic solvent containing a basic compound and water. Therefore it is done.
[0021]
The dispersion medium of the silica fine particle mixed solution dispersion can be converted into water by, for example, an operation of adding water to the dispersion and distilling off the hydrophilic organic solvent (repeat this operation as necessary). . The amount of water added at this time is preferably 0.5 to 2 times, preferably about 1 time, in weight ratio with respect to the total amount of the hydrophilic organic solvent used and the amount of alcohol produced.
[0022]
Specific examples of the trifunctional silane compound represented by the general formula (II) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltrimethoxysilane. Examples include trialkoxysilanes such as ethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, and hexyltrimethoxysilane, and these partially hydrolyzed condensates may also be used. .
[0023]
The addition amount of the trifunctional silane compound represented by the general formula (II) is determined based on the SiO0 contained in the used hydrophilic silica fine particles.₂It is good to use 1-O.001 mol, preferably 0.1-O.01 mol per mol of unit.
[0024]
In the step of converting the dispersion medium of the hydrophobic silica fine particle aqueous dispersion into a ketone solvent, an operation of adding a ketone solvent to the dispersion and distilling off 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 weight ratio of the hydrophilic 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.
[0025]
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 . The amount of these used is the SiO0 contained in the used hydrophilic silica fine particles.₂It is recommended to use 0.1 to 0.5 mol, preferably 0.2 to 0.3 mol, per mol of unit.
[0026]
The hydrophobic silica fine particles thus produced can be obtained as a powder by a conventional method.
[0027]
The particle diameter of the fine particles is 0.01 to 5 μm, preferably 0.05 to 0.5 μm, 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 0.01 μm, it is difficult to obtain developer fluidity, caking resistance, and fixing property due to aggregation, and if it exceeds 5 μm, it is likely to cause disadvantages such as modification of the photosensitive member, scraping, and decrease in adhesion to the toner. .
[0028]
The final hydrophobic silica fine particles are surface-treated with a titanate coupling agent. Examples of titanate coupling agents to be used include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropoxy titanium tri (dioctyl pyrophosphate), tetraisopropyl titanate bis (dioctyl phosphite), tetraoctyl titanate bis (dioctyl -Tridecyl phosphite), tetra [2,2-di- (allyloxymethyl) butyl] titanate bis (di-tridecyl phosphite), ethylenedioxytitanium bis (dioctyl pyrophosphate), isopropyl trioctanoyl titanate, isopropyl Isostearoyl dimethacryl titanate, isopropyl isostearoyl diacryl titanate, isopropoxy titanium tri (dioctyl phosphate), isopropyl tri (p-kumi Phenyl) titanate, isopropyl tri (N- aminoethyl-aminoethyl) titanate, bis (p- cumylphenyl) ethylene titanate, diisostearoyl ethylene titanate, can be exemplified oxo ethylenedioxy titanium bis (dioctyl pyrophosphate).
[0029]
The treatment with the titanate coupling agent can be performed by a known technique. For example, the silica fine powder to be treated and the titanate coupling agent may be directly mixed by using a mixer such as a Henschel mixer, or the treatment. Alternatively, a titanate coupling agent may be sprayed onto the silica fine particles. Alternatively, the titanate coupling agent may be dissolved or dispersed in an appropriate solvent, and the resulting solution or dispersion may be mixed with the silica fine particles to be treated, and then the solvent may be removed. At this time, the order of adding each component is not particularly limited. In the above-described production method, a titanate coupling agent may be added to a ketone solvent dispersion of intermediate hydrophobic silica fine particles to coat the surface of the silica fine particles, and then the solvent may be distilled off and dried. . Further, if necessary, pulverization and classification may be performed after drying.
[0030]
The treatment amount of the titanate coupling agent is preferably 0.01 to 20% by weight, more preferably O.5 to 5% by weight, based on the final hydrophobic silica fine particles. If the amount is too large, the fine particles of silica are agglomerated and sufficient fluidity is not obtained, and it is economically disadvantageous. If the amount is too small, it is difficult to sufficiently relax the charging environment dependency of the silica fine powder. It is.
[0031]
The blending amount of the toner external additive in the toner is usually preferably 0.01 to 20 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner. If the blending amount is too small, the amount of adhesion to the toner is small and sufficient fluidity cannot be obtained. If the blending amount is too large, not only the charging property of the toner is adversely affected but also economically disadvantageous.
[0032]
The adhesion state of the toner external additive to the toner particle surface may be merely mechanical adhesion or may be loosely fixed to the surface. Further, the entire surface of the toner particles may be coated or a part thereof may be coated. The surface-treated silica fine particles may be partially aggregated and coated with a titanate coupling agent, but are preferably coated in a single-layer particle state.
[0033]
The toner particles to which the above toner external additive is added are not particularly limited, and known toner particles containing a binder resin and a colorant as main components can be used. Moreover, the charge control agent may be added as needed.
[0034]
The toner for developing a positively charged image to which the external toner additive of the present invention is added can be used as a one-component developer, or it can be mixed with a carrier and used as a two-component developer. When used as a two-component developer, the toner external additive may not be added to the toner particles in advance, but may be added when the toner and the carrier are mixed to coat the surface of the toner. As the carrier, iron powder or the like, or a known one whose surface is resin-coated is used.
[0035]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.
[0036]
Example 1
[Synthesis of spherical hydrophobic silica fine particles]
(Process 1)
To a 3 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 623.7 g of methanol, 41.4 g of water, and 49.8 g of 28% by weight ammonia water were added and mixed. The temperature of this solution was adjusted to 35 ° C. and 1163.7 g of tetramethoxysilane and 418.1 g of 5.4 wt% aqueous ammonia were simultaneously added while stirring. The former was added dropwise over 6 hours and the latter over 4 hours. Even after the tetramethoxysilane was dropped, the mixture was stirred for 0.5 hours and hydrolyzed to obtain a suspension of silica fine particles. Attach an ester adapter and a condenser to a glass reactor, heat to 60 to 70 ° C. and distill off 1132 g of methanol, add 1200 g of water, then heat to 70 to 90 ° C. to distill off 273 g of methanol, An aqueous suspension of silica fine particles was obtained.
[0037]
(Process 2)
To this aqueous suspension, 11.6 g of methyltrimethoxysilane (O.01 mol amount per 1 mol of tetramethoxysilane) was added dropwise at room temperature over 0.5 hours, and after the addition, the mixture was stirred for 12 hours to treat the surface of the silica fine particles. went.
[0038]
(Process 3)
After adding 1440 g of methyl isobutyl ketone to the dispersion thus obtained, it was heated to 80 to 110 ° C. and 1163 g of methanol water was distilled off over 7 hours. To the resulting dispersion, 357.6 g of hexamethyldisilazane was added at room temperature, heated to 120 ° C. and reacted for 3 hours to treat the surface of the silica fine particles with trimethylsilylation. Thereafter, the solvent was distilled off under reduced pressure to obtain 477 g of spherical hydrophobic silica fine particles having an average particle size of 0.12 μm. The following tests were performed on the obtained hydrophobic silica fine particles.
[0039]
<Dispersibility test>
Fine particles are added to an organic compound that is liquid at room temperature so that the weight ratio is 5 to 1, and after shaking for 30 minutes using a shaker, the dispersion state of the fine particles is visually observed. ○: When the total amount of fine particles is dispersed to form a uniform slurry, ○: The total amount of fine particles is wetted by the organic compound, but is not partially dispersed in the organic compound, Δ: The fine particles are not wetted by the organic compound The results are shown in Table 1 with x being the case where both are not mixed.
[0040]
<Aggregation promotion test>
(1) Add fine particles to methanol at a weight ratio of 5: 1 and shake for 30 minutes using a shaker. The particle size distribution of the fine particles treated in this way is measured with a laser diffraction / scattering type particle size distribution measuring apparatus (manufactured by Horiba: LA910).
[0041]
(2) Next, methanol is distilled off from the fine particle dispersion obtained in (1) by heating with an evaporator, and then kept at 100 ° C. for 2 hours.
[0042]
After adding the fine particles thus treated to methanol and shaking for 30 minutes using a shaker, the particle size distribution is measured in the same manner as described above. The ratio of the remaining amount of primary particles is determined based on the particle size distribution obtained in (1). The primary particle size is confirmed in advance by observation with an electron microscope. The results are shown in Table 1.
[0043]
[Preparation of external additives (surface-treated silica fine particles)]
To a 1 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 50 g of the hydrophobic silica fine particles obtained above and 450 g of methyl isobutyl ketone are added and stirred to disperse. 1 g of isopropyl triisostearoyl titanate (Treatment Agent A) was added to this dispersion, heated and mixed at 60 ° C. for 3 hours, and then the solvent was distilled off under reduced pressure to obtain 48 g of titanate coupling agent surface-treated silica fine particles. It was.
[0044]
<Charge measurement of surface-treated silica fine particles>
The surface-treated silica fine particles prepared as described above were added to a carrier ferrite (trade name: FL100, manufactured by Powdertech Co., Ltd.) so that the concentration was 1% by weight and mixed sufficiently to perform tribocharging. The charge amount of this sample was measured with a blow-off powder charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd .: TB-200 type). The results are shown in Table 1.
[0045]
[Production of external additive mixed toner]
After melt-kneading, pulverizing and classifying 96 parts by weight of a polyester resin having a Tg of 60 ° C. and a softening point of 110 ° C. and 4 parts by weight of Carmine 6BC (trade name, manufactured by Sumitomo Color Co., Ltd.), a toner having an average particle size of 7 μm is obtained. It was. 40 g of this toner was mixed with 1 g of the above surface-treated spherical hydrophobic silica fine particles by a sample mill to obtain an external additive mixed toner. Using this, the degree of aggregation was evaluated by the following method.
[0046]
<Measurement of cohesion>
The degree of agglomeration is a value representing the fluidity of the powder, and was measured using a powder tester manufactured by Hosokawa Micron Co., Ltd. and a three-stage sieve in which 200, 100, and 60 mesh sieves were successively stacked. As a measuring means, put powder of 5g toner on the upper 60 mesh sieve of the 3rd stage sieve, apply 2.5V voltage to the powder tester and vibrate the 3 stage sieve for 15 seconds, 60 mesh Aggregates from the powder weight a (g) remaining on the sieve of 100, the powder weight b (g) remaining on the 100 mesh sieve, and the powder weight c (g) remaining on the 200 mesh sieve according to the following formula: Calculate the degree.
[0047]
Aggregation degree (%) = (a + b × 0.6 + c × O.2) × 100/5
The smaller the degree of aggregation, the better the fluidity, and the higher the degree of aggregation, the poorer the fluidity. The results are shown in Table 1.
[0048]
[Preparation of developer]
A developer was prepared by mixing 5 parts of the external additive mixed toner and 95 parts 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. Using this, the toner charge amount and toner adhesion to the photoreceptor were evaluated by the following methods.
[0049]
<Toner charge amount>
The developer was allowed to stand for 1 day under conditions of high temperature and high humidity (30 ° C., 90% RH) and low temperature and low humidity (10 ° C., 15% RH), and then sufficiently mixed under the same conditions for triboelectric charging. The charge amount of each sample was measured using a blow-off powder charge amount measuring device (manufactured by Toshiba Chemical Corporation: TB-200 type) under the same conditions. The results are shown in Table 1.
[0050]
<Evaluation of toner adhesion to photoconductor>
The developer was put into a two-component modified developing machine equipped with an organic photoconductor, and a print test of 30,000 sheets was performed. At this time, the adhesion of the toner to the photoconductor can be detected as white spots in all solid images. The degree of white spots is 10 or more / cm.²"Many", 1-9 pieces / cm²"Less", 0 / cm²Was evaluated as “none”. The results are shown in Table 1.
[0051]
Example 2
467 g of spherical hydrophobic silica fine particles having an average particle size of 0.30 μm were obtained in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 20 ° C. instead of 35 ° C. in Example 1 (Step 1). . Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.
[0052]
Example 3
469 g of spherical hydrophobic silica fine particles having an average particle size of 0.09 μm were obtained in the same manner as in Example 1 except that the hydrolysis temperature of tetramethoxysilane was changed to 40 ° C. instead of 35 ° C. in Example 1 (Step 1). . Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.
[0053]
Example 4
In preparation of external additives (surface-treated silica fine particles), the surface treatment agent was used except that isopropoxy titanium tri (dioctyl pyrophosphate) (treatment agent B) was used instead of isopropyl triisostearoyl titanate (treatment agent A). Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.
[0054]
Example 5
A developer was prepared in the same manner as in Example 1 except that the external additive (surface-treated silica fine particles) was prepared by the following method, and various characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 1.
[Preparation of external additives]
Spartan Luzer RMO-2H (trade name, manufactured by Dalton Co., Ltd.) was charged with the spherical hydrophobic silica fine particles of Example 1, and isopropyl triisostearoyl titanate (treating agent A) at room temperature while stirring the rotating blade at 3200 rpm. After spraying 18 g, the mixture was stirred for 10 minutes. Thereafter, it was dried at 105 ° C. for 24 hours to obtain 726 g of titanate coupling agent surface-treated silica fine particles.
[0055]
Comparative Example 1
451 g of spherical silica fine particles having an average particle size of O.12 μm were obtained in the same manner as in Example 1 except that the trimethylsilylation step on the surface of the fine silica particles using hexamethyldisilazane (step 3) in Example 1 was omitted. A developer was prepared in the same manner as in Example 1 except that this was used, and various characteristics were also evaluated in the same manner as in Example 1. The results are shown in Table 2.
[0056]
Comparative Example 2
In the same manner as in Example 1 except that a mixture of 1000 g of water and 1000 g of methyl isobutyl ketone was used instead of 1200 g of water added after heating to 60 to 70 ° C. and distilling off methanol in (Step 1) of Example 1. As a result, 468 g of spherical hydrophobic silica fine particles having an average particle diameter of 0.12 μm were obtained. Using this, a developer was prepared in the same manner as in Example 1, and various characteristics were evaluated in the same manner as in Example 1. The results are shown in Table 2.
[0057]
Comparative Example 3
A developer in the same manner as in Example 1 except that the spherical hydrophobic silica fine particles obtained in (Step 3) of Example 1 were used as an external additive without being treated with isopropyl triisostearoyl titanate (Processing Agent A). Then, the preparation was performed and various properties were evaluated. The results are shown in Table 2.
[0058]
Comparative Example 4
Implemented except that Nipsil SS50F (trade name, manufactured by Nippon Silica Co., Ltd.) in which the precipitated silica surface was treated with an organosilicon compound was used instead of the spherical hydrophobic silica fine particles obtained in (Step 3) of Example 1. A developer was prepared in the same manner as in Example 1, and various properties were evaluated. The results are shown in Table 2.
[0059]
Comparative Example 5
Example 1 except that Aerosil R972 (trade name, manufactured by Nippon Aerosil Co., Ltd.) obtained by hydrophobizing fumed silica instead of the spherical hydrophobic silica fine particles obtained in (Step 3) of Example 1 was used. Similarly, the preparation of the developer was performed, and various characteristics were evaluated. The results are shown in Table 2.
[0060]
Comparative Example 6
In [Production of external additive mixed toner] described in Example 1, the toner was used without adding spherical hydrophobic silica fine particles to the prepared toner, and a developer was prepared in the same manner as in Example 1. Characteristics were evaluated. The results are shown in Table 2.
[0061]
[Table 1]

Note: MIBK: methyl isobutyl ketone, THF: tetrahydrofuran, D_Five: Decamethylcyclopentasiloxane
Treatment A: Isopropyltriisostearoyl titanate
Treatment agent B: Isopropoxytitanium tri (dioctyl pyrophosphate)
[0062]
[Table 2]

[0063]
【The invention's effect】
The toner external additive for developing an electrostatic charge image of the present invention not only improves the flowability, caking resistance, fixing property and cleaning property of the developer, but also causes alteration and scraping of the photoreceptor and toner adhesion to the photoreceptor. In addition, the effect of imparting charging property that is not affected by the environmental state can be obtained.

Claims (1)

The following conditions (i) and satisfying the (ii), of SiO ₂ units hydrophilic silica fine particle surface in R ² Si0 _3/2 units (wherein, the R ² is a substituted or unsubstituted carbon atoms 1-20 1 valent hydrocarbon group) R ¹ in the resulting hydrophobic silica fine particle surface by introducing a ₃ SiO _1/2 units (wherein, R ¹ represents one substituted or unsubstituted 1 to 6 carbon atoms of the same or different A spherical fine particle of silica having an average primary particle size of 0.01 to 5 μm obtained by introducing a ( valent hydrocarbon group ), and a silica fine particle obtained by treating with a titanate coupling agent. A toner external additive for developing an electrostatic charge image.
(i) When an organic compound which is liquid at room temperature and has a dielectric constant of 1 to 40 F / m and silica fine particles are mixed and shaken at a weight ratio of 5: 1, the silica fine particles are contained in the organic compound. Disperse uniformly.
(ii) The initial presence of primary particles remaining as primary particles when the silica fine particles are dispersed in methanol and the methanol is distilled off by heating with an evaporator and then kept at a temperature of 100 ° C. for 2 hours. The ratio to the primary particle amount is 20% or more.