JP3370614B2 - Ferrite particles containing ammonium salt-based charge control agent and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonium salt-based charge control agent-containing ferrite particle which prevents deterioration of image density and resolution in an electrophotographic copying method and prevents generation of fog to improve transfer efficiency, and a method for producing the same.

[0002]

2. Description of the Related Art At present, electrophotographic copying machines, which are becoming smaller and faster, are capable of enduring continuous operation for a long time under a bad environment of high temperature and high humidity and always producing stable and high quality clear images. Is required. Therefore, excellent environmental stability,
There is a need for an electrophotographic toner that has durability stability and suitable density, is free of black spots, and is capable of copying images with high resolution.

In the conventional technique of preliminary dry mixing, a resin, a coloring agent such as magnetite or carbon black, a charge control agent such as a metal-containing dye, wax and the like are mixed in a mixer such as a Henschel mixer at a time and cooled. , Mix the blades by changing the shape of the rotating blade, the number of rotations and the number of rotations. However, since the resin, the colorant such as magnetite or carbon black, the charge control agent such as a metal-containing dye, and the wax have different particle diameters, specific gravities, and charging characteristics, it is difficult to disperse them uniformly. In particular, since it is difficult to uniformly disperse a colorant such as magnetite or carbon black and a charge control agent such as a metal-containing dye, there is a tendency that the image density and resolution of the toner decrease and fog occurs, and the transfer efficiency decreases.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an ammonium salt-based charge control agent-containing ferrite particle and a method for producing the same, which prevent a decrease in image density and resolution, prevent fog from occurring, and improve transfer efficiency. To do.

[0005]

The ammonium salt-based charge control agent-containing ferrite particles according to the present invention have an average particle diameter including particles in which ferrite and ammonium salt are uniformly mixed and ferrite and ammonium salt are integrally attached. It is composed of particles of 1.0 μm or less.

Since the ferrite and the charge control agent are uniformly mixed, the charge control agent is uniformly dispersed in the toner, the charge control agents do not aggregate with each other, and the toner is not unevenly charged, so that the toner is always stable. The toner is charged with the amount of electric charge thus generated. Since the ferrite particles, which are magnetic materials, are also uniformly dispersed in the toner, other toner particles such as a binder resin are evenly attached to the ferrite particles, and the toner particles are well conveyed along with the ferrite particles by the magnetic roll, and are developed. At this time, a sufficient amount of toner can be supplied to the photoconductor to prevent a decrease in image density. It is also possible to prevent toner particles from scattering from the sleeve due to a decrease in magnetic force. Therefore, the toner using the ferrite particles uniformly containing the charge control agent comprising the ammonium salt of the present invention is
It is possible to prevent a decrease in image density and resolution and the occurrence of fog, and improve the transfer efficiency. When the average particle size of the ferrite particles exceeds 1.0 μm, the dispersibility in the toner is poor and the toner charge amount becomes non-uniform, resulting in a decrease in image density during transfer.

When the ammonium salt is contained in the charge control agent, the compatibility of the charge control agent with the binder resin is good and the toner is given an appropriate amount of positive charge. It also provides a toner that is resistant to environmental changes and has excellent durability. In the embodiment of the present invention, the ammonium salt is an ammonium salt represented by the formula (I) (wherein R ₁ , R ₂ , R ₃ and R ₄ are a hydrogen atom, an alkyl group having 1 to 22 carbon atoms and a carbon number of 6 to Selected from 20 aromatic groups, A being selected from sulfonic acids, metal acids, isopoly acids and heteropoly acids).

[0008]

[Chemical 2]

The salt represented by the formula (I) has good compatibility with the binder resin and has an action of stabilizing the potential on the toner surface. Further, it has excellent charge stability with respect to a carrier for a two-component developer, and has excellent triboelectrification property and stability between toner particles and between a one-component toner and a toner carrier such as a sleeve, so that the image density after transfer is high. No background stains and poor fixing occur. Further, a salt represented by the formula (I) and having a low tinting strength when kneaded with the binder resin depending on the kind of the substituent can be used for the color toner.

The method for producing the ferrite particles containing an ammonium salt type charge control agent according to the present invention comprises the steps of mixing a metal salt containing iron, water and an alkali metal hydroxide and oxidizing the mixture to obtain a ferrite containing solution. The resulting solution, water, ammonium salt, and any one or more of sulfonic acid, metal acid, isopoly acid and heteropoly acid are mixed and neutralized to obtain a mixed solution containing ferrite and ammonium salt. The method includes a step of obtaining and a step of filtering a solid content of the obtained mixed solution, washing with water, drying and pulverizing.

In the production method according to the present invention, the binder resin, the colorant, the charge control agent, the wax and the like are not put in the mixer at one time and reacted, and the ferrite-containing solution, the ammonium salt, the sulfonic acid, the metal acid and the isopolyimide are added. After mixing one or more of the acid and the heteropolyacid, filtration, washing with water, drying and pulverization are carried out to obtain ferrite particles that uniformly contain the charge control agent consisting of an ammonium salt. By kneading the obtained particles with a binder resin, a wax, etc., a high-performance toner capable of suppressing deterioration of image density and resolution and generation of fog can be produced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the ammonium salt-based charge control agent-containing ferrite particles and the method for producing the same according to the present invention will be described below. In the ammonium salt-based charge control agent-containing ferrite particles according to the present invention, as shown in FIG. 1, ferrite 2 and ammonium salt-based charge control agent 3 are uniformly mixed, and ferrite 2 and ammonium salt-based charge control agent 3 are mixed.
And particles having a mean particle size of 1.0 μm or less including particles 1 adhered together.

Since the ferrite 2 and the ammonium salt type charge control agent 3 are uniformly mixed, the charge control agent 3 is uniformly dispersed in the toner and the charge control agent 3 does not aggregate with each other.
No uneven charging occurs on the toner. As a result, the toner is always charged with a stable charge amount. Since ferrite, which is a magnetic material, is also uniformly dispersed in the toner, other toner particles such as binder resin are evenly attached to the ferrite particles containing the charge control agent, and the toner particles are well conveyed by the magnetic roll together with the ferrite particles. Therefore, at the time of development, a sufficient amount of toner can be supplied to the photoconductor to prevent a decrease in image density. It is also possible to prevent toner particles from scattering from the sleeve due to a decrease in magnetic force. Therefore, the toner using the ferrite particles of the present invention, which uniformly contains the charge control agent comprising the ammonium salt, can prevent the deterioration of the image density and resolution and the occurrence of fog, and can enhance the transfer efficiency. The average particle size of the ammonium salt-based charge control agent-containing ferrite particles 1 is 1.0 μm or less, but 0.01 μm
The above is preferable. It is difficult to uniformly pulverize particles having an average particle size of less than 0.01 μm, which causes a large variation in particle size, which is a drawback in manufacturing.

When the ammonium salt is contained in the charge control agent, the compatibility of the charge control agent with the binder resin is good and the toner is given a proper amount of positive charge. It also provides a toner that is resistant to environmental changes and has excellent durability. The ammonium salt comprises an ammonium salt represented by the formula (I). Here, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms and have 1 to 22 carbon atoms.
Alkyl groups and aromatic groups having 6 to 20 carbon atoms, and the anion represented by A is selected from sulfonic acid, metal acid, isopoly acid and heteropoly acid.

[0015]

[Chemical 3]

The alkyl group of formula (I) is selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl. It The aromatic group is selected from phenyl, naphthyl, tolyl, benzyl, p-chlorobenzyl and phenethyl.

In the formula (I), the anion represented by A is sulfonic acid such as benzenesulfonic acid, naphthalenesulfonic acid and naphtholsulfonic acid, iron, chromium, nickel, cobalt, tin, manganese, cerium, silver, zinc, magnesium. , Zirconium, beryllium, copper, aluminum,
Metal acids such as barium, calcium, titanium, indium, lithium and cadmium, isopolytungstic acid,
It is selected from isopoly acids such as isopolyvanadate and isopolymolybdic acid and heteropoly acids such as silicon molybdic acid and phosphotungstic acid.

Specific examples of the ammonium salt used in the present invention are shown by the following chemical formulas.

[Chemical 4]

The content of the ammonium salt type charge control agent in the ferrite particles is 0.1 to 10% by weight. When the content is less than 0.1% by weight, the charge amount is low and the chargeability is not stable. If it exceeds 10% by weight, the charge amount becomes too high, and the proportion of ferrite particles acting as a colorant decreases, so that the toner concentration decreases. It is preferably 0.5 to 3% by weight.

In the method for producing the ferrite particles containing an ammonium salt type charge control agent according to the present invention, first, a metal salt containing iron, water and an alkali metal hydroxide are mixed to obtain 70 to 90 parts.
It is oxidized at 2 ° C. for 2 to 5 hours to obtain a ferrite-containing solution. Then, the obtained solution, water, ammonium salt, and any one of sulfonic acid, metal acid, isopoly acid and heteropoly acid.
One kind or two or more kinds are mixed and neutralized for 30 to 60 minutes to obtain a mixed solution containing ferrite and an ammonium salt. Further, the solid content of this mixed solution is filtered, washed with water, dried and pulverized to produce the ammonium salt-based charge control agent-containing ferrite particles according to the present invention.

In the production method according to the present invention, the binder resin, the colorant, the charge control agent, the wax and the like are not put into the mixer at one time and reacted, and the ferrite-containing solution, the ammonium salt, the sulfonic acid, the metal acid and the isopolyimide are added. By mixing any one or more of the acid and the heteropolyacid, and then filtering, washing with water, drying and pulverizing, ferrite particles uniformly containing a charge control agent composed of an ammonium salt can be obtained.

The metal of the metal salt is iron, chromium, nickel,
Selected from cobalt, tin, manganese, cerium, silver, zinc, magnesium, zirconium, beryllium, copper, aluminum, barium, calcium, titanium, indium, lithium and cadmium, the metal salt is sulfate,
It is selected from chloride salts, nitrates and acetates. The alkaline earth metal hydroxide is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.

The produced ammonium salt-based charge control agent-containing ferrite particles are thoroughly mixed with a binder resin, wax and the like in a mixer such as a ball mill or a Henschel mixer, and then a kneader such as a heat roll kneader or an extruder. Kneading, cooling solidification, crushing, classification and post-treatment (external addition)
do. As a result, it is possible to obtain a toner having a high transfer efficiency by preventing a decrease in image density and resolution and the occurrence of fog. In addition, it can be obtained by a spraying method, a polymerization method or the like.

The binder resin is polystyrene, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer,
Styrene resin such as styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-butadiene copolymer, saturated polyester resin, unsaturated polyester resin, epoxy resin, phenol resin, maleic acid resin, coumarone It is selected from one or two kinds of resin, chlorinated paraffin, xylene resin, vinyl chloride resin, polypropylene and polyethylene.

As the colorant and the charge control agent, ammonium salt-based charge control agent-containing ferrite particles are used. The content of the ammonium salt-based charge control agent-containing ferrite particles in the toner is 5 to 70% by weight. If it is less than 5% by weight, the magnetic force is weak and the toner cannot be carried on the magnetic roll, so that a sufficient amount of toner cannot be supplied to the photoconductor and the image density is lowered. On the other hand, when it exceeds 70% by weight, the proportion of the binder resin component in the toner is small and the fixing property of the toner on the paper is deteriorated. It is preferably 25 to 55% by weight. The wax is selected from low molecular weight polypropylene, low molecular weight polyethylene, microcrystalline wax, carnauba wax, sazol wax, paraffin wax, aliphatic solid alcohol, and the like.

If necessary, a fluidizing agent, a charging aid, an abrasive and the like may be added to the toner. Fine particles of silica, titanium oxide, alumina and the like, fine particles obtained by hydrophobizing these with silicon oil, silicon varnish, silane coupling agent, etc., inorganic materials such as metal oxides such as calcium titanate, metal carbides and metal nitrides. It is selected from fine particles, organic fine particles such as methyl methacrylate, polyvinylidene fluoride and polystyrene, fine particles of organic metal compounds such as zinc stearate and calcium stearate, and the like.

[0027]

EXAMPLES Examples of the ammonium salt-based charge control agent-containing ferrite particles according to the present invention and a method for producing the same will be described together with comparative examples. All formulations are parts by weight.

Example 1 <Synthesis of Ammonium Salt-Based Charge Control Agent-Containing Ferrite Particles> Aqueous solution in which 3000 parts of ferrous sulfate was added to 4400 parts of water, and 1000 parts of sodium hydroxide was added to 1500 parts of water. Mix and stir with and blow 90 while blowing air.
The ferrite-containing solution was obtained by carrying out an oxidation reaction at 5 ° C. for 5 hours.
Add decylpentylammonium chloride 4.9 to this solution.
Part of water to 20 parts of water was added, followed by an aqueous solution of 4.6 parts of sodium 1-naphthol-5-sulfonate added to 10 parts of water, and the mixture was stirred for 30 minutes for neutralization reaction to cause ferrite and ammonium salts. A mixed solution containing and was obtained. The solid content of the obtained mixed solution was separated by filtration, washed with water, and then at 120 ° C. for 6 minutes.
By drying and pulverizing for an hour, 840 parts of ferrite (FeO.Fe ₂ O ₃ ) particles having an average particle size of 0.5 μm and containing 1.0% of an ammonium salt type charge control agent uniformly were obtained.

<Manufacturing and Performance Confirmation of Toner> Styrene-acrylic acid ester copolymer 49 parts Low molecular weight polypropylene NP-505 (manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Ammonium salt-based charge control agent-containing ferrite particles 49 parts After dry-mixing with a mixer (Henschel mixer), the mixture was kneaded with a twin-screw kneader whose temperature was set to 130 ° C. Cool the obtained kneaded product and use a hammer mill for about 2 mm
After coarse pulverization to the following, finely pulverized with a jet pulverizer having a coarse powder classification function, and classified with an air flow type classifier to have an average particle size of 9.
1 μm raw toner was obtained. To 100 parts of the obtained raw toner, 0.3 parts of hydrophobic colloidal silica and 1.0 part of calcium titanate were added and mixed with a mixer (Henschel mixer), and then aggregates were removed by a vibrating screen to obtain a toner. A commercially available copying machine (trade name: NP-400RE)
As a result of a continuous copying test of 10,000 sheets by Canon Inc.), as shown in Table 1, the image density and resolution did not decrease, fog did not occur, and the transfer efficiency was high.

Comparative Example 1 <Manufacture and Performance Confirmation of Toner> Styrene-acrylic ester copolymer 49 parts Low molecular weight polypropylene NP-505 (manufactured by Mitsui Petrochemical Co., Ltd.) 2 parts Ferrite (FeO.Fe ₂ O ₃ ). Particle powder 44.6 parts Charge control agent (ammonium salt-based) 0.4 parts The above materials were dry-mixed with a mixer (Henschel mixer), and then kneaded with a twin-screw kneader whose temperature was set at 130 ° C. Cool the obtained kneaded product and use a hammer mill for about 2 mm
After coarse pulverization to the following, finely pulverized with a jet pulverizer having a coarse powder classification function, and classified with an air flow type classifier to have an average particle size of 9.
2 μm raw toner was obtained. To 100 parts of the obtained raw toner, 0.3 parts of hydrophobic colloidal silica and 1.0 part of calcium titanate were added and mixed with a mixer (Henschel mixer), and then aggregates were removed by a vibrating screen to obtain a toner. A commercially available copying machine (trade name: NP-400RE)
As a result of conducting a continuous copying test of 10,000 sheets by Canon Inc.), the image density and the resolution decreased as shown in Table 1,
There was a lot of fog and the transfer efficiency was low.

Example 2 <Synthesis of Ammonium Salt-Based Charge Control Agent-Containing Ferrite Particles> An aqueous solution prepared by adding 2640 parts of ferrous sulfate to 3870 parts of water and an aqueous solution prepared by adding 880 parts of sodium hydroxide to 1320 parts of water. And mix and stir and blow 115 while blowing air.
The ferrite-containing solution was obtained by performing an oxidation reaction at 6 ° C. for 6 hours.
To this solution was added an aqueous solution of 13.1 parts of hexadecylpentylammonium chloride in 25 parts of water, followed by an aqueous solution of 3.9 parts of potassium ferrate in 25 parts of water.
The mixture was stirred for a period of time for neutralization reaction to obtain a mixed solution containing ferrite and an ammonium salt. The solid content of the obtained mixed solution was separated by filtration, washed with water, dried at 120 ° C. for 6 hours and pulverized to uniformly contain 2.0% of an ammonium salt-based charge control agent having an average particle size of 0.4 μm. Ferrite (FeO ・ F
was obtained e ₂ O ₃₎ particles 740 parts.

<Production / Performance Confirmation of Toner> Saturated polyester resin 67 parts Low molecular weight polypropylene NP-505 (manufactured by Mitsui Petrochemical Co., Ltd.) 3 parts Ammonium salt type charge control agent-containing ferrite particles 30 parts Mixer (Henschel mixer) ) Was dry-mixed and then kneaded with a twin-screw kneader having a temperature set at 130 ° C. Cool the obtained kneaded product and use a hammer mill for about 2 mm
After coarse pulverization to the following, finely pulverized with a jet pulverizer having a coarse powder classification function, and classified with an air flow type classifier to have an average particle size of 9.
3 μm raw toner was obtained. To 100 parts of the obtained raw toner, 0.3 parts of hydrophobic colloidal silica and 0.5 part of methyl methacrylate fine particles were added and mixed with a mixer (Henschel mixer), and then aggregates were removed by a vibrating screen to obtain a toner. A commercially available copying machine (trade name NP-6
As a result of performing a continuous copying test of 10,000 sheets by 062 Canon Inc.), as shown in Table 1, the image density and resolution did not decrease, fog did not occur, and the transfer efficiency was high.

Comparative Example 2 <Production / Performance Confirmation of Toner> Saturated polyester resin 67 parts Low molecular weight polypropylene NP-505 (manufactured by Mitsui Petrochemical Co., Ltd.) 3 parts Ferrite (FeO.Fe ₂ O ₃ ) particle powder 28 parts Charge Control agent (ammonium salt-based) 2 parts The above materials were dry-mixed by a mixer (Henschel mixer), and then kneaded by a twin-screw kneader whose temperature was set at 130 ° C. Cool the obtained kneaded product and use a hammer mill for about 2 mm
After coarse pulverization to the following, finely pulverized with a jet pulverizer having a coarse powder classification function, and classified with an air flow type classifier to have an average particle size of 9.
A raw toner of 0 μm was obtained. To 100 parts of the obtained raw toner, 0.3 parts of hydrophobic colloidal silica and 0.5 part of methyl methacrylate fine particles were added and mixed with a mixer (Henschel mixer), and then aggregates were removed by a vibrating screen to obtain a toner. A commercially available copying machine (trade name NP-6
As a result of conducting a continuous copying test of 10,000 sheets by 062 Canon Inc.), as shown in Table 1, the image density and the resolution were lowered, fogging was frequently generated, and the transfer efficiency was also low.

Table 1 shows the results of evaluating the copied image at the start of the continuous copying test and the copied image at the end of each of the examples and comparative examples for each item. The Electrophotographic Society Test Chart No. 1-R was used as a copy sample. As the image density, the density of the black solid portion of the copied image was measured with a Macbeth densitometer. The resolution was evaluated by visually observing the copied image with a magnifying glass and counting the number of individual thin lines. For fog, the density of the non-image portion of the copied image was measured with a Macbeth densitometer. The transfer efficiency is a value obtained by subtracting 100 from a value obtained by dividing the amount of waste toner (reduction amount in the developing portion) by the amount of used toner (increase amount in the waste toner portion) and multiplying by 100.

[0035]

[Table 1]

[0036]

EFFECT OF THE INVENTION By using the ammonium salt type charge control agent-containing ferrite particles and the method for producing the same according to the present invention, it is possible to provide a high quality electrophotographic toner having a high transfer efficiency, which prevents deterioration of image density and resolution and generation of fog. .

[Brief description of drawings]

FIG. 1 is an enlarged view of ferrite particles containing an ammonium salt-based charge control agent according to the present invention.

[Explanation of symbols]

1 ・ ・ Ammonium salt type charge control agent-containing ferrite particles, 2 ・ ・ Ferrite, 3 ・ ・ Ammonium salt (charge control agent)

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 9/083 G03G 9/097

Claims (5)

(57) [Claims] 1. An ammonium salt-based charge control comprising particles having an average particle size of 1.0 μm or less including particles in which ferrite and ammonium salt are uniformly mixed and in which ferrite and ammonium salt are integrally attached. Agent-containing ferrite particles. 2. An ammonium salt is an ammonium salt represented by the formula (I) (wherein R ₁ , R ₂ , R ₃ and R ₄ are a hydrogen atom, an alkyl group having 1 to 22 carbon atoms and a carbon atom having 6 to 20 carbon atoms). Selected from aromatic groups, A being selected from sulfonic acids, metal acids, isopoly acids and heteropoly acids) An ammonium salt-based charge control agent-containing ferrite particle according to claim 1, which comprises: 3. A step of mixing a metal salt containing iron, water and an alkali metal hydroxide and oxidizing the mixture to obtain a ferrite-containing solution, the obtained solution, water, an ammonium salt, and a sulfonic acid. , Metal acid, isopoly acid and heteropoly acid 1
And a step of mixing and neutralizing one kind or two or more kinds to obtain a mixed solution containing ferrite and an ammonium salt, and a step of filtering a solid content of the obtained mixed solution, washing with water, drying and pulverizing A process for producing ferrite particles containing an ammonium salt-based charge control agent, which comprises: 4. The metal of the metal salt is iron, chromium, nickel, cobalt, tin, manganese, cerium, silver, zinc,
Magnesium, zirconium, beryllium, copper, aluminum, barium, calcium, titanium, indium,
The method for producing ferrite particles containing an ammonium salt-based charge control agent according to claim 3, wherein the ferrite particles are one kind or two or more kinds selected from lithium and cadmium. 5. The method for producing a ferrite particle containing a charge control agent according to claim 3, wherein the metal salt is one or more selected from sulfates, chlorides, nitrates and acetates.