JP2949630B2 - Negative electrostatic toner for developing electrostatic images - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for visualizing a latent electrostatic image in an image forming method such as electrophotography and electrostatic recording.

[Prior Art] Conventionally, as an electrophotographic method, US Pat. No. 2,297,691,
Various methods are described in JP-B-42-23910 and JP-B-43-24748.

Developing methods applied to the electrophotographic method and the like are roughly classified into a dry developing method and a wet developing method. The former is further classified into a method using a two-component developer and a method using a one-component developer.

Conventional toners applied to these dry development methods include:
Fine powders in which dyes and pigments are dispersed in a natural or synthetic resin are used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and finely pulverized to about 1 to 30 μm are used as toner. As the magnetic toner, a toner containing magnetic particles such as magnetite is used. In the case of a system using a two-component developer, the toner is usually used by mixing with carrier particles such as glass beads and iron powder.

Any toner must have a positive or negative charge, depending on the polarity of the electrostatic latent image to be developed. For that purpose, it is common to add a compound called a charge control agent.

Further, various chemical substances are added according to the fixing property of the image and other required characteristics.

In particular, for the purpose of improving various image characteristics such as resolution, density uniformity and fog, external addition of silica fine powder has been widely performed to impart fluidity to toner.

[Problem to be Solved by the Invention] However, although the above problem is improved by the external addition of silica, a new problem of environmental dependency of image quality arises.
For this purpose, the present situation is that some heaters are provided in the copying machine or other additives are externally added, so that the copier can be managed. However, remodeling of the copying machine itself leads to an increase in price, and the use of other external additives often causes new problems. In particular, this is the biggest problem in a full-color copying machine that needs to faithfully reproduce a halftone image. Therefore, there is a strong demand in the art for the development of a silica fine powder that significantly reduces the environmental fluctuation of the toner when externally added.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic image development method with a low environmental dependency, in which silica fine powder treated with a positive frictionally chargeable silane coupling agent and a negative frictionally chargeable silane coupling agent, which solves the above problems, is externally added. To provide a toner.

Still another object of the present invention is to provide a method for externally adding silica fine powder treated with a positive triboelectrically charging silane coupling agent and a negative triboelectrically charging silane coupling agent, which is less dependent on the environment, and has a reproducibility of a halftone image. And to provide a color toner for developing an electrostatic image excellent in color.

[Means and Actions for Solving the Problems] The present invention relates to a negatively charged electrostatic image development in which silica fine powder having negative frictional charge is externally added to toner particles having at least a colorant and a binder resin. The negatively chargeable silica fine powder is treated with (i) a positive frictionally chargeable silane coupling agent and a negative frictionally chargeable silane coupling agent, and (ii) the triboelectric charge amount is reduced. Absolute value: temperature 30 ° C, humidity 85% RH, temperature 23 ° C, humidity 60
Under each environment under 15% RH and temperature 15 ℃ and humidity 10% RH,
The present invention relates to a toner for developing a negatively chargeable electrostatic image, which is less than 150 μC / g.

In order to obtain a toner having good environmental stability, the conventional idea has been to suppress the water absorption of silica and to stabilize the triboelectric charge of silica itself. As such an example, Japanese Patent Laid-Open Publication No.
No. 42354 or JP-B-54-16219 as an external additive of hydrophobic silica to a toner. JP-A-56-123550 discloses external addition of silica treated with a silane coupling agent to a toner. Thus, prior developments have focused solely on treating agents and methods for hydrophobizing silica.

The present inventors have confirmed that the largest cause of environmental instability of the toner is due to environmental fluctuations in the triboelectric charge amount of the toner.
In addition, it has been found that, even with toner not externally added with silica, the amount of triboelectric charge changes due to environmental fluctuations, and external addition of silica further increases this. The degree of the environmental change in the amount of triboelectricity of the toner varies depending on the type of toner carrier such as a carrier or a sleeve, but silica has the greatest influence.

In addition, the amount of triboelectricity of silica-externally added toner varies depending on the environment. Therefore, in order to eliminate the environmental dependence of the triboelectricity of the toner, it is not sufficient for the triboelectricity of silica itself to be free from environmental fluctuations. Therefore, it is necessary to change so as to cancel the change of the toner not having silica externally added. Further, silica having a high absolute value of the triboelectric charge is not preferable from the viewpoint of stabilizing the environment of the toner. Here, the silica having a high triboelectric charge is defined as | 150 | μC when the triboelectric charge with iron powder (EFV200 / 300 made by Nippon Iron Powder) is measured by a blow-off method at a silica / iron powder ratio of 3: 100. / g or more.

The present inventors have newly found the above-mentioned knowledge, and have developed silica having low frictional charging property, and the amount of frictional charging decreases as the humidity decreases.

As a result of diligent studies, both the positive triboelectric silane coupling agent and the negative triboelectric silane coupling agent were used in combination,
Moreover, the negative triboelectrically chargeable silane coupling agent has a larger absolute value of the triboelectric charge amount than the positive triboelectrically chargeable silane coupling agent, and the positive triboelectrically chargeable silane coupling agent has a negative triboelectrically chargeable silane coupling agent. By using a combination in which the rate of increase in the absolute value of the triboelectric charge is increased as the humidity becomes lower than the agent, it is found that silica having a low triboelectric charge and a low triboelectric charge as the humidity becomes lower can be obtained. The present invention has been completed.

As the silica fine powder of the present invention before the silica fine powder is treated with the silane coupling agent, both dry silica and wet silica can be used. Silica is preferred.

The dry method referred to herein is a method for producing silica fine powder generated by vapor phase oxidation of a silicon halide derivative. For example, in a method utilizing the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen-hydrogen, the basic reaction formula is as follows.

SiC ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HC In this production process, for example, by using another metal halogen derivative such as aluminum chloride and titanium chloride together with a silicon halide derivative, a composite fine powder of silica and another metal oxide is obtained. It is also possible and includes these.

On the other hand, as a method for producing the silica fine powder used in the present invention by a wet method, various conventionally known methods can be applied. For example, decomposition of sodium silicate with an acid, if represented by a general reaction formula (hereinafter, the reaction formula is abbreviated), Na ₂ O.XSiO ₂ + HC + H ₂ O → SiO ₂ .nH ₂ O + NaC In addition, ammonia salts of sodium silicate or alkali Decomposition with salts, after producing an alkaline earth metal silicate from sodium silicate, a method of decomposing with an acid to silicic acid, a method of converting a sodium silicate solution to silicic acid with an ion exchange resin, natural silicic acid or There is a method using a silicate.

Silica such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc. can be applied to the silica fine powder here, in addition to anhydrous silicon dioxide (silica).

Among the above silica fine powders, those having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) measured by the BET method by nitrogen adsorption give good results.

Examples of the positive frictionally chargeable silane coupling agent include a coupling agent having an organic group such as an amino group or a nitrogen-containing heterocyclic group. As the nitrogen-containing heterocyclic group, there are an unsaturated heterocyclic group and a saturated heterocyclic group, each of which can be applied. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the following.

Further, nitrogen-containing salt compounds such as quaternary ammonium salts and pyridinium salts can also be exemplified. Further, phosphines, phosphonium salts and the like can be exemplified. However, an amino group and a nitrogen-containing heterocyclic group are preferable in consideration of easiness of synthesis and cost.

Various things can be illustrated as a negative friction charging silane coupling agent.

For example, conventional silane coupling agents having no organic groups containing nitrogen or phosphorus are negatively triboelectrically chargeable. This is thought to be due to the Si-C bond, but such silane coupling agents are highly preferred. However, in this case, the negative triboelectrification due to the Si—C bond decreases with an increase in the carbon number of the hydrocarbon directly bonded to Si, and therefore, in the present invention, those having 7 or more carbon atoms should not be used. Since it is not preferable, the number of carbon atoms is preferably 6 or less, more preferably 5 or less.

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

Further, a halogen atom, a carbonyl group, a sulfonyl group,
A silane coupling agent having an organic group containing a cyano group or the like can also be used effectively.

One of the features of the present invention is that a negative frictionally chargeable silica is obtained by a combination of a positive frictionally chargeable silane coupling agent and a negative frictionally chargeable silane coupling agent as described above. Therefore, it is necessary to combine the negative frictionally chargeable silane coupling agent so that the absolute value of the triboelectric charge amount is larger than that of the positive frictionally chargeable silane coupling agent. In addition, it is necessary to combine the positive frictionally chargeable silane coupling agent so that the rate of increase in the amount of triboelectric charge under low humidity is higher than that of the negative frictionally chargeable silane coupling agent.

To obtain the silica fine powder of the present invention, either of the positive and negative silane coupling agents may be treated first, but in consideration of the uniformity of the treatment, a mixture of the positive and negative silane coupling agents in advance is used. Preferably, the silica is treated.

Further, the processing ratio of the positive triboelectric charging silane coupling agent and the negative triboelectric charging silane coupling agent varies depending on the type of the processing agent used or the triboelectric charging amount of the intended silica, and is therefore uniquely determined. Absent. However, considering the ease of processing and the uniformity of the processing, it is preferable that the processing amounts of the positive and negative silane coupling agents do not greatly differ between the two,
It is preferable that the throughput ratio falls within the range of 1/20 to 20/1.

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

1-1) Silane coupling agent having negative triboelectricity due to Si-C bond 1-2) Silane coupling agent having negative triboelectrification due to halogen, carbonyl, phenol, cyano group, etc. 1-3) Silane coupling agent having negative triboelectric charge due to organic carboxylic acid derivative 2-1) Silane coupling agent having positive triboelectric charging property by amino group 2-2) Silane coupling agent having positive triboelectrification due to nitrogen-containing heterocycle 2-3) Silane Coupling Agent Having Positive Triboelectric Charging Property Due to Quaternary Ammonium Salt The amount of the silica fine powder used in the present invention is 0.01 to 5%, preferably 0.05 to 2%, based on the weight of the toner.
It is. The silicas used in the present invention may be used together or some known silicas may be used in combination.

On the other hand, the resin for forming the toner particles used in the present invention includes, for example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene and a substituted product thereof; styrene-p-chlorostyrene. Copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, Styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-
Styrene-based copolymers such as isoprene copolymer and styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic resin, acrylic resin, methacrylic resin, polyvinyl acetate, Silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used. Further, a crosslinked styrene copolymer is also a preferable binder resin.

Examples of the comonomer for the styrene monomer of the styrene-based copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacryl. Monocarboxylic acid having a double bond such as acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; for example, maleic acid, butyl maleate Dicarboxylic acids having a double bond, such as methyl maleate, dimethyl maleate and the like, and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc .; ethylene, propylene, Vinyl monomers such as ethylene-based olefins such as tylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Are used alone or in combination of two or more. As the crosslinking agent, a derivative having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl derivative such as divinylbenzene, divinylnaphthalene or the like; for example, ethylene glycol diacrylate, ethylene glycol diacrylate, or the like. 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 a derivative having three or more vinyl groups; used alone or as a mixture.

When using a pressure fixing method, a binder resin for a pressure fixing toner can be used, for example, polyethylene,
Examples include polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, and paraffin.

It is also preferable to add a negative charge control agent to impart negative frictional charge to the toner particles. Any known negative charge control agent can be used without any particular limitation. Examples of such a charge control agent include a complex of a salicylic acid derivative, a complex of a monoazo derivative, a phenol derivative, an organic acid such as carboxylic acid and sulfonic acid, and a polymer having these in a side chain. In order to finely adjust the triboelectric charge of the toner particles, a slight amount of a positive charge control agent may be added. Of course, the triboelectricity of the binder resin can be utilized without using the charge control agent.

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

Further, the toner of the present invention is used by being mixed with a carrier. As the carrier that can be used in the present invention, known carriers can be used, for example, iron powder, ferrite powder, powder having magnetic properties such as nickel powder, glass beads, and the like, and the surface thereof is made of resin or the like. What was processed is mentioned.
Further, as the resin for coating the carrier surface, styrene-
Acrylate copolymer, styrene-methacrylate copolymer, acrylate copolymer, methacrylate copolymer, silicone resin, fluorine-containing resin, polyamide resin, ionomer resin, polyphenylene sulfide resin, etc. or these Can be used.

The electrostatic charge developing toner of the present invention can be used as a magnetic toner by containing a magnetic material. As the magnetic material used, iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; iron, cobalt,
Metals such as nickel or these metals and aluminum,
Examples include alloys with metals such as cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof. These magnetic materials preferably have an average particle size of 0.1 to 1 μm, preferably about 0.1 to 0.5 μm. The amount contained in the magnetic toner is 40 to 150 parts by weight based on 100 parts by weight of the binder resin component. , Preferably 60 to 120 parts by weight.

The toner of the present invention may optionally contain additives. Examples of the additive include a lubricant such as zinc stearate, a polishing agent such as cerium oxide and silicon carbide, a fluidity imparting agent such as aluminum oxide, an anti-caking agent, and a conductivity imparting agent such as carbon black and tin oxide. There are agents.

Fluorine-containing polymer fine powder such as polyvinylidene fluoride fine powder is also a preferable additive from the viewpoint of fluidity, abrasiveness, charge stability and the like.

Also, for the purpose of improving the releasability at the time of hot roll fixing, wax-like substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax, etc.
The addition of about 5% by weight of the toner is also a preferred embodiment of the present invention.

In producing the toner particles according to the present invention, the above-described toner constituent materials are sufficiently mixed by a ball mill or other mixer, then kneaded well using a hot kneader of a hot roll kneader or an extruder, and cooled and solidified. Thereafter, a method of obtaining toner particles by mechanical pulverization and classification is preferable. Alternatively, a method of dispersing a constituent material in a binder resin solution and then spray drying to obtain toner particles; A method for producing a toner by mixing a monomer to be formed with a predetermined material to form an emulsified suspension and then polymerizing to obtain toner particles; or a so-called microcapsule toner particle comprising a core material and a shell material. A method of incorporating a predetermined material into the core material, the shell material, or both of them;
And other methods can be applied. Further, if necessary, the desired additives are sufficiently mixed by a mixer such as a Henschel mixer to produce the toner particles according to the present invention.

The toner of the present invention can be used for development for visualizing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, by a conventionally known means.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. All parts in the following formulations are parts by weight.

Example 1 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Further, the obtained fine powder is classified and removed by ultra-fine and coarse powders simultaneously and strictly by a multi-division classifier (Nippon Mining Co., Ltd. Elbow Jet Classifier) utilizing the Coanda effect to obtain a volume average particle size.
8.3 μm black fine powder (toner particles) was obtained.

On the other hand, silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) was used with the silane coupling agent shown in Compound Example (1-1-3) and the silane coupling agent shown in Compound Example (2-1-3). At a mixing ratio of 15/5 (temperature: 150 ° C., time: 2 hours, treatment amount: 100 g of silica, 20 g of silane coupling agent) to obtain a fine silica powder of the present invention.

0.5% of this silica fine powder was externally added to the above black fine powder to obtain a toner.

Acrylic-coated ferrite carrier with an average particle size of 65 μm
6 parts of the obtained toner was mixed with 100 parts to prepare a developer.

Next, using a commercially available color copying machine CLC-1 (manufactured by Canon Inc.), a copy test of this toner was performed under a constant development contrast potential in each environment.

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.43 and was sharp. In addition, the uniformity of density of a solid image and the reproducibility of a halftone image were excellent. In addition, 15
Images were obtained under the environment of ℃, 10% and 30 ° C, 85%, however, the image density was 1.38 and 1.50, respectively, and almost no image density fluctuation due to environmental change was recognized. Further, no change was observed in the image quality such as the density uniformity of the solid image and the reproducibility of the halftone image due to the environmental change.

Table 1 shows the environmental change of the triboelectric charge amount of silica and the toner before and after the external addition of silica. It can be seen that silica successfully compensates for the environmental change of the triboelectric charge amount of the toner before the external addition of silica.

Example 2 A fine blue powder (toner particles) was obtained in the same manner as in Example 1 except that 5 parts of carbon black in Example 1 was changed to 4 parts of a copper phthalocyanine pigment (CI Pigment Blue 15).

The fine silica powder used in Example 1 was replaced with the fine blue powder described above.
0.5% was externally added to obtain a toner.

Acrylic-coated ferrite carrier with an average particle size of 65 μm
6 parts of the obtained toner was mixed with 100 parts to prepare a developer.

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

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.46 and was sharp. In addition, the uniformity of density of a solid image and the reproducibility of a halftone image were excellent. In addition, 15
The images were obtained under the environment of ℃, 10% and 30 ° C, 85%, respectively, and the image density was 1.40, 1.51, respectively. Further, no change was observed in the image quality such as the density uniformity of the solid image and the reproducibility of the halftone image due to the environmental change.

Table 1 shows the environmental change of the triboelectric charge amount of silica and the toner before and after the external addition of silica. It can be seen that silica successfully compensates for the environmental change of the triboelectric charge amount of the toner before the external addition of silica.

Example 3 A red fine powder (toner particles) was obtained in the same manner as in Example 1 except that 5 parts of carbon black in Example 1 was changed to 3.5 parts of a quinacridone pigment (CI Pigment Red 122).

The silica fine powder used in Example 1 was used as the red fine powder described above.
0.5% was externally added to obtain a toner.

Acrylic-coated ferrite carrier with an average particle size of 65 μm
6 parts of the obtained toner was mixed with 100 parts to prepare a developer.

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

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.45 and was sharp. In addition, the uniformity of density of a solid image and the reproducibility of a halftone image were excellent. In addition, 15
Images were obtained under the environment of 10 ° C, 10% and 30 ° C, 85%, but the image density was 1.41 and 1.49. Further, no change was observed in the image quality such as the density uniformity of the solid image and the reproducibility of the halftone image due to the environmental change.

Table 1 shows the environmental change of the triboelectric charge amount of silica and the toner before and after the external addition of silica. It can be seen that silica successfully compensates for the environmental change of the triboelectric charge amount of the toner before the external addition of silica.

Example 4 A yellow fine powder (toner particles) was obtained in the same manner as in Example 1 except that carbon black in Example 1 was replaced with 5 parts of CI Pigment Yellow 175 parts.

The silica fine powder used in Example 1 was replaced with the yellow fine powder described above.
0.5% was externally added to obtain a toner.

Acrylic-coated ferrite carrier with an average particle size of 65 μm
6 parts of the obtained toner was mixed with 100 parts to prepare a developer.

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

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.47 and was sharp. In addition, the uniformity of density of a solid image and the reproducibility of a halftone image were excellent. In addition, 15
Images were obtained under the environment of ℃, 10% and 30 ° C, 85%, however, the image density was 1.42 and 1.52, respectively, and almost no image density fluctuations due to environmental changes were observed. Further, no change was observed in the image quality such as the density uniformity of the solid image and the reproducibility of the halftone image due to the environmental change.

Table 1 shows the environmental change of the triboelectric charge amount of silica and the toner before and after the external addition of silica. It can be seen that silica successfully compensates for the environmental change of the triboelectric charge amount of the toner before the external addition of silica.

Example 5 Black, cyan, magenta, and black used in Examples 1 to 4
When a full-color image was obtained using the yellow developer, a vivid full-color image excellent in color mixing and gradation was obtained. In addition, excellent images having no difference were obtained in all the above-mentioned environments without special measures for the copying machine body.

Comparative Example 1 In the same manner as in Example 1, except that 0.5% of the silica fine powder used in Example 1 was changed to 0.5% of silica fine powder treated with only dimethyldichlorosilane of Compound Example (1-1-2). A toner was obtained and a copy test was performed.

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

Example 6 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Further, the obtained fine powder is classified and removed by ultra-fine and coarse powders simultaneously and strictly by a multi-division classifier (Nippon Mining Co., Ltd. Elbow Jet Classifier) utilizing the Coanda effect to obtain a volume average particle size.
12.5 μm of black fine powder (toner particles) 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 (2-1-7) were added to silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.). At a mixing ratio of 19/1 (temperature: 150 ° C., time: 2 hours, treatment amount: 100 g of silica, 20 g of silane coupling agent) to obtain silica fine powder of the present invention.

0.4% of this silica fine powder was externally added to the above black fine powder to obtain a toner.

Acrylic-coated ferrite carrier with an average particle size of 65 μm
5 parts of the obtained toner was mixed with 100 parts to prepare a developer.

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

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.47 and was sharp. In addition, the uniformity of density of a solid image and the reproducibility of a halftone image were excellent. In addition, 15
The images were obtained under the environment of ℃, 10% and 30 ° C, 85%, respectively, and the image density was 1.40, 1.51, respectively. Further, no change was observed in the image quality such as the density uniformity of the solid image and the reproducibility of the halftone image due to the environmental change.

Example 7 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified by a fixed wall type air classifier. The classified powder was purified.

Further, the obtained classified powder is strictly classified and removed simultaneously with a multi-segment classification device (Elbojet classifier manufactured by Nippon Steel Mining Co., Ltd.) utilizing the Coanda effect to simultaneously remove ultrafine powder and coarse powder, thereby obtaining a volume average particle diameter of 11.1 μm. A black fine powder (toner particles) 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 added to silica fine powder Aerosil 130 (manufactured by Nippon Aerosil Co., Ltd.). Was treated at a mixing ratio of 15/5 (temperature: 150 ° C., time: 2 hours, treatment amount: 100 g of silica, 13 g of silane coupling agent) to obtain silica fine powder of the present invention.

0.4% of this silica fine powder was externally added to the above black fine powder to obtain a toner.

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

The image obtained in an environment of 23 ° C. and 60% had a sufficiently high density of 1.40 and was sharp. Also, the uniformity of density of the solid image was excellent. Further, images were obtained under the environment of 15 ° C., 10% and 30 ° C., 85%, respectively. Also, no change in the image quality such as the density uniformity of the solid image due to the environmental change was observed.

Example 8 After the above materials were mixed well in a blender, they were kneaded with a biaxial kneading extruder set at 150 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, and the obtained finely pulverized powder was classified by a fixed wall type air classifier to purify the classified powder.

Further, the obtained classified powder is strictly classified and removed by a multi-division classifier utilizing a Coanda effect (an elbow jet classifier manufactured by Nittetsu Mining Co., Ltd.) at the same time, and the volume average particle size is removed.
A fine blue powder (toner particles) of 11.8 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 added to silica fine powder Aerosil 300 (manufactured by Nippon Aerosil Co., Ltd.). Was treated at a mixing ratio of 10/10 (temperature: 150 ° C., time: 2 hours, treatment amount: 30 g) to obtain a silica fine powder of the present invention.

0.3% of this silica fine powder was externally added to the above blue fine powder to obtain a toner.

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

The image obtained under the environment of 23 ° C. and 60% had a sufficiently high density of 1.34 and was sharp. Also, the uniformity of density of the solid image was excellent. Further, images were obtained under the environment of 15 ° C., 10% and 30 ° C., 85%, respectively. Also, no change in the image quality such as the density uniformity of the solid image due to the environmental change was observed.

[Effects of the Invention] As described above, (i) treated with a positive triboelectrically chargeable silane coupling agent and a negative triboelectrically chargeable silane coupling agent, and (ii) the absolute value of the triboelectric charge amount is 30 ° C. ° C
Humidity 85% RH, temperature 23 ℃, humidity 60% RH and temperature 15 ℃
In each environment under 10% RH, the negative frictionally chargeable silica fine powder having a triboelectric chargeability of less than 150 μC / g fluctuates so as to well compensate the triboelectric charge of the toner without silica.

Therefore, the toner to which the above-mentioned specific negatively triboelectrically-chargeable silica fine powder is externally added does not change in image quality due to environmental changes, and can always provide an image with excellent image quality.

In particular, when applied to a color toner, the environment of a halftone image does not fluctuate, so that an excellent full-color image can always be provided under any environment.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-66558 (JP, A) JP-A-2-66564 (JP, A) JP-A-2-66565 (JP, A) JP-A-1-6655 219760 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 9/08

Claims (10)

(57) [Claims] A negatively chargeable electrostatic image developing toner in which silica fine powder having negative frictional chargeability is externally added to toner particles having at least a colorant and a binder resin. The silica fine powder has been treated with (i) a positive triboelectrically chargeable silane coupling agent and a negative triboelectrically chargeable silane coupling agent, and (ii) the absolute value of the triboelectric charge is a temperature of 30 ° C. and a humidity of 85%. Under RH, temperature 23 ° C, humidity 60%
In each environment under RH and temperature 15 ° C and humidity 10% RH, 15
A toner for developing a negatively chargeable electrostatic image, which is less than 0 μC / g. 2. The silica fine powder having negative triboelectric charging property,
Temperature 30 ° C, 85% RH, 23 ° C, 60% RH, 15
2. The negatively chargeable electrostatic image developing toner according to claim 1, wherein the toner has a triboelectric charge characteristic in which the absolute value of the triboelectric charge amount decreases in the order of 10 ° C. and 10% RH. 3. The toner for developing a negatively chargeable electrostatic image according to claim 1, wherein the positively triboelectrically chargeable silane coupling agent has a nitrogen-containing organo group. 4. The toner for developing a negatively chargeable electrostatic image according to claim 1, wherein said negatively triboelectrically chargeable silane coupling agent has an alkyl group having 6 or less carbon atoms. 5. The toner for developing a negatively chargeable electrostatic image according to claim 1, wherein the negatively triboelectrically chargeable silane coupling agent has an organic acid. 6. The toner for developing a negatively chargeable electrostatic image according to claim 1, wherein the negatively triboelectrically chargeable silane coupling agent has a halogen atom. 7. The toner for developing a negatively chargeable electrostatic image according to claim 1, wherein the negatively triboelectrically chargeable silane coupling agent has a carbonyl group. 8. The method of claim 1, wherein the negative frictionally chargeable silane coupling agent is
Negatively chargeable toner according to claim 1, characterized in that it comprises a C ₆ H ₄ -OH group. 9. The toner according to claim 1, wherein the silane coupling agent having a negative frictional charge has a cyano group. 10. The toner according to claim 1, wherein the toner particles are magnetic toner particles containing 40 to 150 parts by weight of a magnetic material as the colorant based on 100 parts by weight of the binder resin. Negatively chargeable electrostatic image developing toner.