JPH03216663A - Toner for developing negative electrostatic images - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for visualizing electrostatic latent images in image forming methods such as electrophotography and electrostatic recording.

[Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,69
1, Special Publication No. 42-23910, and Special Publication No. 43
Various methods are described in JP-A-24748 and the like.

The developing methods applied to these electrophotographic methods include:
Broadly speaking, there are dry development methods and wet development methods. The former method is further divided into a method using a two-component developer and a method using a component developer.

Toners used in these dry development methods have conventionally been fine powders in which dyes and pigments are dispersed in natural or synthetic resins.
It is used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. Further, in the case of a system using a two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Either toner must have a positive or negative charge depending on the polarity of the electrostatic latent image being developed. for that,
It is common to add a compound called a charge control agent.

Additionally, various chemical substances are added depending on the image fixability and other required properties. In particular, for the purpose of improving various image characteristics such as resolution, density uniformity, and fog, it is widely practiced to externally add silica fine powder to impart fluidity to toner.

[Problems to be Solved by the Invention] However, although the above-mentioned problems can be improved by externally adding silica, a new problem of environmental dependence of image quality arises. For this reason, the current situation is that copying machines are equipped with heaters and other additives are added externally to make use of them. However, modifying the copying machine itself leads to an increase in price, and the use of other external additives often creates new problems. In particular, this is the biggest problem in full-color copying machines, which need to faithfully reproduce even halftone images. Therefore, in this technical field, there is a strong desire to develop a fine silica powder that significantly reduces environmental fluctuations in toner when added externally.

[Means and effects for solving the problems] An object of the present invention is to provide a novel silica fine powder treated with a positive and negative triboelectric silane coupling agent that solves the above-mentioned problems.

A further object of the present invention is to provide a toner for developing electrostatic images with less environmental dependence, to which the fine silica powder of the present invention is externally added.

Still another object of the present invention is to provide a toner for developing electrostatic images which has less environmental dependence and which has good reproducibility of halftone images, to which the fine silica powder of the present invention is externally added.

The present invention is a toner in which fine silica powder having negative triboelectric charging properties is externally added to colored fine powder particles having at least a colorant and a binder resin, and the fine silica powder having negative tribocharging properties The present invention relates to a toner for developing negatively charged electrostatic images, which is characterized in that it is a fine silica powder treated with a charging silane coupling agent and a negatively triboelectrically charging silane coupling agent.

In order to obtain toner with good environmental stability, it is necessary to suppress the water absorption of silica and stabilize the amount of triboelectric charging of silica itself.
This was the conventional way of thinking. An example of such a method is JP-A-49-4, in which silica is treated with silicone oil.
No. 2354, or Japanese Patent Publication No. 16219/1989, which describes the external addition of hydrophobic silica to toner. Further, as a method of externally adding silica treated with a silane coupling agent to a toner, there is a method disclosed in Japanese Patent Application Laid-open No. 123550/1983. Thus, conventional developments have focused attention solely on treating agents and treatment methods for making silica hydrophobic.

The present inventors have confirmed that the greatest cause of environmental instability of toner is environmental fluctuations in the amount of triboelectric charge of toner. Moreover, it has been found that even in a toner without external addition of silica, the amount of triboelectric charge changes due to changes in the environment, and that external addition of silica further increases this. The degree of environmental variation in the amount of triboelectric charge of toner varies depending on the type of toner carrier such as carrier or sleeve, but silica has the most influence.

Moreover, even in toners without external additives of silica, the amount of triboelectric charge changes depending on the environment, so in order to eliminate the environmental dependence of the amount of triboelectric charge of toner, it is necessary to assume that the amount of triboelectric charge of silica itself does not change in the environment. It is sufficient and needs to be varied to offset the change in the toner without external addition of silica. Also,
Silica, which has a high absolute value of triboelectric charge, is not preferred from the viewpoint of environmental stabilization of the toner. Here, silica with a high triboelectric charge amount is l − 1 50 1pc
/g or more.

Based on the above-mentioned new findings, the present inventors developed silica that has low triboelectric charging properties and the amount of triboelectric charging decreases as the humidity decreases.

As a result of intensive studies, we found that both a positive triboelectric silane coupling agent and a negative triboelectric silane coupling agent were used together, and that the negative triboelectric silane coupling agent was better than the positive triboelectric silane coupling agent. A combination in which the absolute value of the triboelectric charge amount is large, and the rate of increase in the absolute value of the triboelectric charge amount becomes larger as the humidity becomes lower for the positive triboelectric silane coupling agent than for the negative triboelectric silane coupling agent. The present inventors have discovered that by using silica, it is possible to obtain silica that has low triboelectric chargeability and whose triboelectric charge decreases as the humidity decreases, and has completed the present invention.

As the silica fine powder of the present invention before being treated with the silane cobbling agent, both dry process silica and wet process silica can be used, but in order to impart the inherent fluidity of silica, the dry process Silica is preferred.

The dry method mentioned here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halogen derivative. For example, silicon tetrachloride gas in oxygen hydrogen? The basic reaction formula is as follows.

SiCi) 4+ 2 Ha+ O■→Sift + 4
HCilAlso, by using other metal halogen derivatives such as aluminum chloride and titanium chloride together with silicon halogen derivatives in this manufacturing process, it is also possible to obtain a composite fine powder of silica and other metal oxides, and these are also included. do.

On the other hand, various conventionally known methods can be applied to produce the silica fine powder used in the present invention by a wet method.

For example, the decomposition of sodium silicate with an acid can be expressed by a general reaction formula (the reaction formula is omitted below): NazO・XSiO■+}l(J) +HzO −*S
iOz'nHzO +NaCI! Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, generation of alkaline earth metal silicate from sodium silicate and decomposition with acid to produce silicic acid, and method of decomposing sodium silicate solution with ion exchange resin. There are methods such as using silicic acid, and using natural silicic acid or silicate.

The silica fine powder referred to herein can be any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate.

Among the above silica fine powders, the specific surface area due to nitrogen adsorption measured by the O-T method is 30 m2/g or more (especially 50 to 400 m2/g).
m''/g) gives good results.

Examples of positive triboelectric silane coupling agents include coupling agents having organic groups such as amino groups and nitrogen-containing heterocyclic groups. Examples of the nitrogen-containing heterocyclic group include an unsaturated heterocyclic group and a saturated heterocyclic group, and each of the known ones can be applied. Examples of the unsaturated heterocyclic group include the following.

Examples of saturated heterocyclic groups include the following:
Ru.

Further, nitrogen-containing salt compounds such as quaternary ammonium salts and viridinium salts can also be exemplified. Further examples include phosphine and phosphonium salts. However, in consideration of ease of synthesis and cost, amino groups and nitrogen-containing heterocyclic groups are preferred.

Various types of negative triboelectric silane coupling agents can be exemplified.

For example, conventional silane coupling agents without nitrogen or phosphorus containing organic groups are negatively triboelectric. Although this is thought to be due to the SL-C bond, such a silane coupling agent is highly preferred. However, in this case, the negative triboelectrification caused by the SL-C bond decreases as the number of carbon atoms in the hydrocarbon directly bonded to Si increases, so in the case of the present invention, hydrocarbons with 7 or more carbon atoms cannot be used. . Preferably << has 5 or less carbon atoms.

Further, a silane coupling agent having an organic acid such as a carboxylic acid or a sulfonic acid, or an organic group containing an acidic hydroxyl group such as a phenol is also preferable.

Furthermore, a silane coupling agent having an organic group containing an octarogen atom, a carbonyl group, a sulfonyl group, a cyano group, etc. can also be effectively used.

The present invention uses the above-mentioned positive triboelectric silane. One of the features is that a negatively triboelectrically charged silica can be obtained by combining a coupling agent and a negatively triboelectrically charged silane coupling agent. Therefore, it is necessary to combine the negative triboelectric silane coupling agents so that the absolute value of the triboelectric charge amount is larger than that of the positive triboelectric silane coupling agents. Moreover, it is necessary to combine the positive triboelectrically charging silane coupling agents so that the rate of increase in triboelectric charge under low humidity is greater than that of the negative triboelectrically charging silane coupling agents.

To obtain the silica fine powder of the present invention, whichever of the positive and negative silane coupling agents may be treated first, but in consideration of the uniformity of the treatment, it is preferable to use a mixture of both the positive and negative silane coupling agents in advance. It is preferable to treat the silica by

In addition, the processing amount ratio of the positive triboelectric silane coupling agent and the negative triboelectric silane coupling agent varies depending on the type of treatment agent used or the amount of triboelectrification of the target silica, so it cannot be determined uniquely. I can't do it. However, considering ease of processing and uniformity of processing, it is preferable that the processing amounts of both positive and negative silane coupling agents do not differ greatly.
The throughput ratio is preferably within the range of l/20 to 20/l.

Representative examples of the silane coupling agent of the present invention are shown below, but these are not intended to limit the present invention in any way.

(Left below) 1-1) Silane coupling agent having negative triboelectric charging properties due to SL-C bond 1-1-1) 1-1-2) 1-1-8) ? I1.0 \CIlaO SiClI■CII. CI+. / CI+. 0 l-2 >> Silane coupling agent having negative triboelectric charging properties due to halogen, carbonyl, phenol, cyano group, etc. 1-2-1) 1-2-2) l 2-5) 1-2-6) 1- 2-7) 1-2-8) C0 1-2-9) CI{. CH. 0 \ CHmCHaO SjCH*CHtCH*CN/ CI. C.I. 0 1-2-11) 1-2-12) l-3) Silane coupling agent having negative triboelectric chargeability due to organic carboxylic acid derivative 2-1) Silane coupling agent having positive triboelectricity chargeability due to amino group tlmLl 2-1-2) coso \ 1 CH. 2-1-10) CI{30\2-2) Silane coupling agent that has positive triboelectric charging properties due to nitrogen-containing heterocycle 2-3) Silane coupling agent that has positive triboelectric charging properties due to quaternary ammonium salt Preparation II. The applied amount of the silica fine powder used in the present invention is 0.00% based on the weight of the toner. Ol~5%, preferably 0.05
~2%. Further, the silicas used in the present invention can be used together or in combination with known silicas.

On the other hand, examples of the resin for forming the toner particles used in the present invention include monopolymers of styrene and substituted products thereof such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymers; Coalescence, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylic nitrile Copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylic nitrile indene Styrenic copolymers such as copolymers; polyvinyl chloride, phenolic resin, naturally modified phenolic resin, natural resin-modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin , furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaron indene resin, petroleum resin, etc. can be used. Further, crosslinked styrenic copolymers are also preferred binder resins.

Examples of comonomers for the styrene monomer in the styrenic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacrylate. Acids, monocarboxylic acids with double bonds such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylic nitrile, acrylamide, etc., if substituted; for example, maleic acid, maleic acid, etc. Dicarboxylic acids and their substituted substances having double bonds such as butyl acid, methyl maleate, dimethyl maleate, etc.; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc.; e.g. ethylene, brobylene, butylene Vinyl monomers such as ethylene olefins such as; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Can be used alone or in combination. As the crosslinking agent, derivatives having two or more polymerizable double bonds are mainly used, such as aromatic divinyl derivatives such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol diacrylate, etc. Carboxylic acid esters having two double bonds such as methacrylate and 1,3-butanediol dimethacrylate; divinyl derivatives such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone;
and derivatives having three or more vinyl groups; are used alone or as a mixture.

In addition, when using a pressure fixing method, it is possible to use a pressure fixing resin, such as polyethylene,
Examples include boribropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isobrene copolymer, linear saturated polyester, and paraffin.

It is also preferable to add a negative charge control agent to impart negative triboelectrification to the toner particles. Any known negative charge control agent can be used and is not particularly limited. Such charge control agents include, for example, complexes of salicylic acid derivatives, complexes of monoazo derivatives, phenol derivatives, or carboxylic acids,
Examples include organic acids such as sulfonic acid and polymers having them in side chains. Further, in order to finely control the amount of triboelectric charge of the toner particles, a small amount of a positive charge control agent may be added. Of course, it is also possible to utilize the triboelectricity of the binder resin without using a charge control agent.

Coloring agents used in the present invention include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, lid cyanine green, Hansa Yellow G, rhodamine 6G, calco oil blue chrome yellow, quinacridone, benzidine. Conventionally known dyes and pigments such as yellow rose bengal, triarylmethane dyes and pigments, monoazo dyes and pigments, and disazo dyes and pigments can be used alone or in combination.

Furthermore, the toner of the present invention is used in combination with a carrier. As carriers that can be used in the present invention, known carriers can be used, such as iron powder, ferrite powder, magnetic carriers such as nickel powder, glass beads, etc., and carriers whose surfaces are treated with resin etc. Those who have done so will be listed. In addition, examples of the resin that coats the carrier surface include styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester copolymer, methacrylic ester copolymer, silicone resin, fluorine-containing resin, Polyamide resin, ionomer resin, polyphenylene sulfide resin, etc. or a mixture thereof can be used.

Further, the toner for electrostatic charge development of the present invention can also be used as a magnetic toner by containing a magnetic material. Magnetic materials used include iron oxides such as magnetite, gamma iron monoxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel, or these metals with aluminum, cobalt, copper, lead, magnesium, tin, Zinc, antimony, beryllium, bismuth, cadmium, calcium,
Examples include alloys with metals such as manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof. It is desirable that these magnetic materials have an average particle diameter of about 0.1 to IPm, preferably about 0.1 to 0.5Pn+, and the amount contained in the magnetic toner is 100% of the binder resin component.
40 to 150 parts by weight, preferably 60 to 150 parts by weight
It is 120 parts by weight.

The toner of the present invention may contain additives, if necessary. Examples of additives include lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, flow agents such as aluminum oxide, anti-caking agents, and conductivity imparters such as carbon black and tin oxide. There is a drug.

Further, fine powder of a fluorine-containing polymer such as fine powder of polyvinylidene fluoride is also a preferable additive from the viewpoint of fluidity, polishability, charging stability, and the like.

In addition, in order to improve mold release properties during hot roll fixing, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc.
Adding about 5% by weight to the toner is also one of the preferred embodiments of the present invention.

In manufacturing the toner according to the present invention, the toner constituent materials as described above are thoroughly mixed using a ball mill or other mixer, then kneaded well using a hot roll kneader or extruder, and then cooled and solidified. After that, it is preferable to obtain the toner by mechanical crushing and classification.Another method is to obtain the toner by dispersing the constituent materials in a binder resin solution and then spray drying; A polymerization toner production method in which a toner is obtained by mixing a predetermined material with the monomer to be emulsified and then polymerizing it to form an emulsified suspension; Methods such as a method of containing a predetermined material in the shell material, or both of these materials can be applied. Furthermore, the toner according to the present invention can be produced by sufficiently mixing desired additives with a mixer such as a Henschel mixer, if necessary.

The toner of the present invention can be used in all conventionally known methods for developing electrostatic charge images in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples, but these are not intended to limit the present invention in any way.

Note that all parts in the following formulations are parts by weight.

Example 1 The above materials were thoroughly mixed in a blender and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder is strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Nippon Steel Mining Co., Ltd.'s Elbow Jet Classifier), resulting in a volume average particle size of 8.
．． A black fine powder of 3Pm was obtained.

On the other hand, the silane coupling agent shown in the compound example (1-1-31) and the silane coupling agent shown in the compound example (2-1-31) were added to the silica fine powder Aerosil 200 (manufactured by Nippon Aerosil ■) at a mixing ratio of 15. /5 treatment (temperature 150℃,
A silica fine powder of the present invention was obtained for 2 hours and a treatment amount of 20 g of silane coupling agent per 100 g of silica.

A toner was obtained by externally adding 0.5% of this silica fine powder to the above-mentioned black fine powder.

A developer was prepared by mixing 6 parts of the obtained toner with 100 parts of an acrylic coated ferrite carrier having an average particle diameter of 65) zm.

Next, we used a commercially available color copier CLC-1 (Canon ■
Copying tests of this toner were conducted using a toner (manufactured by Co., Ltd.) under constant development contrast potential conditions.

The image obtained in an environment of 23°C and 60% has a density of 1.
43, which was sufficiently high and clear. Furthermore, the density uniformity of solid images and the reproducibility of halftone images were also excellent. Furthermore, images were obtained under environments of 15° C., 10% and 30° C., 85%, but the image density was 1.38 and 1.50, respectively, and almost no image density fluctuation was observed due to environmental changes. or,
No changes were observed in image quality such as density uniformity of solid images and reproducibility of halftone images due to environmental changes.

Furthermore, Table 1 shows silica and environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica, and it can be seen that silica successfully compensates for environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica.

Example 2 A colored fine powder was obtained in the same manner as in Example 1, except that 5 parts of carbon black in Example 1 was replaced with 4 parts of a copper lid cyanine pigment (cr. Pigment Blue 15).

A toner was obtained by externally adding 0.5% of this silica fine powder to the blue fine powder described above.

A developer was prepared by mixing 6 parts of the obtained toner with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 pm.

This developer was subjected to a copying test in exactly the same manner as in Example 1.

Images obtained in an environment of 23°C and 60% have a density of 1,
46, which was sufficiently high and clear. Furthermore, the density uniformity of solid images and the reproducibility of halftone images were also excellent. Furthermore, images were obtained under environments of 15° C., 10% and 30° C., 85%, but the image density was 1.40 and 1.51, respectively, and almost no image density fluctuation was observed due to environmental changes. or,
No changes were observed in image quality such as density uniformity of solid images and reproducibility of halftone images due to environmental changes.

Furthermore, Table 1 shows silica and environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica, and it can be seen that silica compensates for environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica.

Example 3 A colored fine powder was obtained in the same manner as in Example 1, except that 5 parts of carbon black in Example 1 was replaced with 3.5 parts of a quinacridone pigment (CI Pigment Red 122).

The silica fine powder used in Example 1 was added to the red fine powder described above.
．． A toner was obtained by adding 5% externally.

A developer was prepared by mixing 6 parts of the obtained toner with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 pm.

This developer was subjected to a copying test in exactly the same manner as in Example 1.

The image obtained in an environment of 23° C. and 60% has a density of I.
45, which was sufficiently high and clear. Furthermore, the density uniformity of solid images and the reproducibility of halftone images were also excellent. Furthermore, images were obtained under environments of 15° C., 10% and 30° C., 85%, but the image density was 1.41 and 1.49, respectively, and almost no image density fluctuation was observed due to environmental changes. or,
No changes were observed in image quality such as density uniformity of solid images and reproducibility of halftone images due to environmental changes.

Furthermore, Table 1 shows the environmental variations in silica and the triboelectric charge amount of the toner before and after the external addition of silica, and it can be seen that silica successfully compensates for the I-boundary variation in the triboelectric charge amount of the toner before and after the external addition of silica.

Example 4 5 parts of carbon black in Example 1 was added to C.I. I. Example 1 except that 5 parts of Pigment Yellow 17 were used.
A colored fine powder was obtained in the same manner as above.

The silica fine powder used in Example 2 was added to the yellow fine powder described above.
．． A toner was obtained by adding 5% externally.

A developer was prepared by mixing 6 parts of the obtained toner with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 μm.

This developer was subjected to a copying test in exactly the same manner as in Example 1.

The image obtained in an environment of 23°C and 60% has a density of 1.
47, which was sufficiently high and clear. Furthermore, the density uniformity of solid images and the reproducibility of halftone images were also excellent. Furthermore, images were obtained under environments of 15° C., 10% and 30° C., 85%, but the image density was 1.42 and 1.52, respectively, and almost no image density fluctuation was observed due to environmental changes. or,
No changes were observed in image quality such as density uniformity of solid images and reproducibility of halftone images due to environmental changes.

Furthermore, Table 1 shows silica and environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica, and it can be seen that silica successfully compensates for environmental variations in the triboelectric charge amount of the toner before and after the external addition of silica.

Example 5 When a full-color image was obtained using the black, cyan, magenta, and yellow developers used in Examples 1 to 4, a bright full-color image with excellent color mixing and gradation was obtained. Moreover, even without any special modifications to the copying machine itself, excellent images were obtained with no difference under all the above-mentioned environments.

Comparative Example 1 A toner was obtained in the same manner as in Example 1, except that 0.5% of the silica fine powder used in Example 1 was replaced with 0.5% of silica fine powder treated with dimethylsilane, and a copying test was conducted.

A good image with a density of 1.40 was obtained under an environment of 23°C and 60%, but the image density decreased to 1.03 under an environment of 15°C and 10%. This is due to an increase in the amount of triboelectric charge as shown in Table 1.

Example 6 The above materials were thoroughly mixed in a blender, and then kneaded in a twin-screw kneading extrusion mode set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type air classifier to refine the classified powder.

Furthermore, the obtained classified powder is strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Nippon Steel Mining Co., Ltd.'s Elbow Jet Classifier) to obtain a volume average particle size of 1.
A black fine powder of 2.5 μm was obtained.

On the other hand, the silane coupling agent shown in compound example (1-1-1) and the silane coupling agent shown in compound example (2-1-71) were added to silica fine powder Aerosil 2oO (manufactured by Nippon Aerosil ■) at a mixing ratio. 19/L treatment (temperature 150℃
The silicate fine powder of the present invention was obtained by treating 100 g of silica and 20 g of silane coupling agent for 2 hours.

A toner was obtained by externally adding 0.4% of this silica fine powder to the above-mentioned black fine powder.

A developer was prepared by mixing 5 parts of the obtained toner with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 pm.

Next, a copying test of this toner was conducted using a commercially available color copying machine CLC-1 (manufactured by Canon Inc.) without environmental correction.

The image obtained in an environment of 23°C and 60% has a density of 1.
47, which was sufficiently high (clear). Furthermore, the uniformity of solid images and the reproducibility of halftone images were also excellent. Furthermore, images were obtained under environments of 15° C., 10% and 30° C., 85%, but the image density was 1.40 and 1.51, respectively, and almost no image density fluctuation was observed due to environmental changes. Furthermore, no changes in image quality such as density uniformity of solid images and reproducibility of halftone images due to environmental changes were observed.

Example 7 The above materials were thoroughly mixed in a blender, and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained mixed material was cooled, coarsely pulverized with a cutter mill, and then finely pulverized with a pulverizer using a jet stream.
The resulting finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder is strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Elbowjet classifier manufactured by Nippon Steel Mining Co., Ltd.) to obtain a volume average particle size of 11. A black fine powder of 1#Lm was obtained.

On the other hand, the silane coupling agent shown in Compound Example (1-2-1) and the silane coupling agent shown in Compound Example (2-2-4) were mixed into silica fine powder Aerosil 130 (manufactured by Nippon Aerosil ■). Treated at a ratio of 15/5 (temperature 150°C,
The silica fine powder of the present invention was obtained by treating 13 g of silane coupling agent for 100 g of silica for 2 hours.

A toner was obtained by externally adding 0.4% of this silica fine powder to the above-mentioned black fine powder.

Next, a copying test of this toner was conducted using a commercially available copying machine NP-6650 (manufactured by Canon Inc.).

The image obtained in an environment of 23°C and 60% has a density of 1.
40, which was sufficiently high and clear. Furthermore, the density uniformity of the solid image was also excellent. Further, 15°C, 1O% and 30°C,
Images were obtained even under the 85% environment, but each was 1.44.
1.35, and no image density fluctuation was observed due to environmental changes. Furthermore, no changes in image quality such as density uniformity of solid images due to environmental changes were observed.

Example 8 The above materials were thoroughly mixed in a blender, and then kneaded in a twin-screw kneading extruder set at 150°C.

The resulting mixture was cooled and coarsely ground using a cutter mill.
The resulting finely pulverized powder was classified using a fixed wall type wind classifier to refine the classified powder.

Furthermore, the obtained classified powder is strictly classified and removed at the same time to remove ultrafine powder and coarse powder using a multi-division classifier that utilizes the Coanda effect (Nippon Steel Mining Co., Ltd.'s Elbow Jet Classifier) to obtain a volume average particle size of 1.
A black fine powder of 1.8 μm was obtained.

On the other hand, the silane coupling agent shown in Compound Example (1-2-7) and the silane coupling agent shown in Compound Example (2-2-6) were mixed into silica fine powder Aerosil 300 (manufactured by Nippon Aerosil ■). Processed at a ratio of 10/10 (temperature 150
°C, time 2 hours. The silica fine powder of the present invention was obtained in a treated amount of 30 g).

A toner was obtained by externally adding 0.3% of the silica fine powder described above.

Next, a copying test of this toner was conducted using a commercially available copying machine NP-6650 (manufactured by Canon Inc.).

Images obtained in an environment of 23°C and 60% have a density of 1,
34, which was sufficiently high (clear). Furthermore, the density uniformity of the solid image was also excellent. Furthermore, 15℃, 10% and 30℃
, images were obtained even under 85% environment, but each was 1.35
, 1.31, and no fluctuations in image density due to environmental changes were observed. In addition, no changes in image quality such as density uniformity of the background images due to environmental changes were observed.

(Leaving space below) Table 1 $1 High temperature, high temperature, Book 2, Normal temperature, Normal temperature, Book 3, Low temperature, low humidity [Effects of the invention] As described above, the silica of the present invention effectively compensates for the amount of triboelectric charge of the toner without external addition of silica. The environment changes.

Therefore, the toner to which silica of the present invention is externally added does not fluctuate in image quality due to environmental changes, and can always provide images of excellent image quality.

In particular, when applied to color toners, halftone images are not affected by environmental changes, so excellent full-color images can always be provided under any environment.

Claims (9)

[Claims] (1) A toner in which fine silica powder having negative triboelectricity is externally added to colored fine powder particles having at least a colorant and a binder resin, and the fine silica powder having negative triboelectricity is positively triboelectrically charged. 1. A toner for developing a negatively charged electrostatic image, characterized in that the toner is a fine silica powder treated with a silane coupling agent and a silane coupling agent that is negatively charged. (2) The negatively chargeable electrostatic image developing toner according to claim 1, wherein the positively triboelectrically chargeable silane coupling agent has a nitrogen-containing organo group. (3) The negatively chargeable electrostatic image developing toner according to claim 1, wherein the positively triboelectrically chargeable silane coupling agent has a phosphorus-containing organo group. (4) Claim (1) characterized in that the negative triboelectric silane coupling agent has an alkyl group having 7 or less carbon atoms.
The negatively charged electrostatic image developing toner described above. (5) The negatively chargeable electrostatic image developing toner according to claim (1), wherein the negatively triboelectrically chargeable silane coupling agent contains an organic acid. (6) The negatively chargeable electrostatic image developing toner according to claim 1, wherein the negatively triboelectrically chargeable silane coupling agent has a halogen atom. (7) The negatively chargeable electrostatic image developing toner according to claim (1), wherein the negatively triboelectrically chargeable silane coupling agent has a carbonyl group. (8) The negatively chargeable electrostatic image developing toner according to claim (1), wherein the negatively triboelectrically chargeable silane coupling agent contains a phenol derivative. (9) The negatively chargeable electrostatic image developing toner according to claim (1), wherein the negatively triboelectrically chargeable silane coupling agent has a cyano group.