JP2001022117A - Toner and its manufacturing method - Google Patents

Abstract

(57) [Problem] To develop a toner having low-temperature fixability and heat-resistant storage stability and a method for producing the same. A toner characterized in that an acidic group-containing resin is fixed on the surface of resin particles (I) containing a colorant using a polyester resin as a binder resin. This toner is prepared by mixing an aqueous dispersion (A) of resin particles (I) with an acidic group-containing resin which becomes self-water dispersible and / or water-soluble by neutralization with an aqueous medium in the presence of a basic neutralizing agent. An aqueous dispersion (B) of fine particles (II) having a smaller average particle size and a higher glass transition temperature than the resin particles (I) obtained by the phase inversion emulsification is uniformly mixed, and the resin particles (I) are acidified. Fine particles (II) are precipitated on the surface of the powder, then the liquid medium is removed therefrom and dried, and the dried powder is subjected to stirring and mixing under heating. The resin particles (I) are obtained by mixing a mixture containing a polyester resin and a colorant as essential components with an aqueous medium and inverting the mixture by phase inversion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively chargeable toner for developing an electrostatic image used in an electrophotographic copying machine or a printer, and a method for producing the same.

[0002]

2. Description of the Related Art As a dry method for producing a toner, there is a pulverization method in which a colorant or the like is melted and kneaded in a binder resin, followed by pulverization and classification. In a wet method, a polymerizable monomer in which a colorant or the like is dispersed is used. After polymerization in a liquid medium to form colored particles, a polymerization method of removing the particles as a dry powder,
There is a phase inversion emulsification method described in JP-A-5-66600 and the like.

In recent years, there has been a great demand for powder toner for low-temperature fixing for improving image quality such as resolution and reducing power consumption. Since it is effective to reduce the particle size of the toner to improve the image quality, it is easy to control the chargeability and ensure the powder fluidity when the particle size is reduced, and the wet method toner is expected to be advantageous in terms of cost. Is being actively developed.

With respect to the fixability, the binder resin contains a high molecular weight component in order to widen the hot offset resistance temperature range, and the glass transition temperature of the binder resin is lowered in order to obtain low temperature fixability. It is possible to respond by containing the components. However, when a resin having a low glass transition temperature is used as the binder resin, the heat resistance storage stability of the toner becomes insufficient, and there is a problem in practical use.

[0005] In order to satisfy such conflicting performance, there has been proposed a method of producing a toner in which toner particles have a multi-layer structure and resins having different compositions are used inside and outside the particles. This manufacturing method promotes low-temperature fixability by using a resin having a low glass transition temperature inside the particles, while using a resin having a higher glass transition temperature than the inside of the particles on the surface of the particles. Another object of the present invention is to provide a toner excellent in heat roll fixability while securing necessary heat storage stability.

As a method for producing a toner having a multilayer structure, for example, a production method by an in situ polymerization method, an interfacial polymerization method, a coacervation method or a spray-dry method has been proposed. In addition, Japanese Patent Application Laid-Open No. Hei 5-333584
JP-A-8-334927 discloses a resin exhibiting self-water dispersibility by neutralization, a resin exhibiting non-self-water dispersibility, or a resin having lower self-water dispersibility than the above-mentioned neutralized resin, and By dissolving or dispersing a colorant or the like in an organic solvent, and then adding an appropriate amount of water while stirring, without using a suspension stabilizer such as an emulsifier, phase-inversion emulsification in an aqueous medium to produce fine particles. And a method for producing a toner having a multilayer structure by a phase inversion emulsification method in which the produced fine particles are dried to obtain a dry toner.

However, even with these manufacturing methods, it has not always been possible to obtain a toner having a sufficiently satisfactory fixing temperature range. In particular, heat-resistant storage stability could not be secured while keeping the fixing start temperature low.

Further, in the method of producing a toner by the phase inversion emulsification method, JP-A-9-292737 and JP-A-10-10774 have been proposed in order to improve hot offset resistance.
In the publication, an intraparticle crosslinking method is proposed. This technique can improve the hot offset resistance of the phase inversion emulsification toner, but also has a problem that the low-temperature fixability of this toner is still insufficient.

[0009]

The problem to be solved by the present invention is to provide a spherical toner which has excellent low-temperature fixability, excellent heat storage stability, and excellent image quality such as resolution and gradation. It is to provide the manufacturing method. In particular, it is an object of the present invention to provide a full-color toner having good hue and gloss in addition to the above characteristics.

[0010]

As a result of intensive studies on the above problems, the following has been found and the present invention has been completed.

1. A toner in which an acidic group-containing resin having a higher glass transition temperature than the resin is fixed to the surface of resin particles (I) containing a colorant and a polyester resin as essential components has excellent low-temperature fixability and heat-resistant storage stability. And a good image can be obtained.

2. In the toner of the present invention, a carboxyl group is preferable as the acidic group of the resin to be fixed to the surface, and the resin has an average circularity of 0.97 or more (in the present invention, a flow-type particle image manufactured by Toa Medical Electronics Co., Ltd.). Analyzer FPI
(Measured at P-1000).

3. Such a toner is made of resin particles (I)
To the aqueous dispersion (A) by neutralization,
Alternatively, fine particles having an average particle size smaller than the resin particles (I) and a higher glass transition temperature, obtained by mixing a water-soluble acidic group-containing resin with an aqueous medium in the presence of a basic neutralizing agent and phase-inversion emulsification. The aqueous dispersion (B) of (II) is uniformly mixed, and the fine particles (II) are precipitated on the surface of the resin particles (I) with an acid. Is suitably obtained by stirring and mixing under heating.

4. The resin particles (I) are mixed with an aqueous medium in the presence of a basic neutralizer, and a phase inversion emulsification is conducted by mixing a mixture containing an acidic group-containing polyester resin which becomes self-water dispersible by neutralization and a colorant as essential components. Thus, it can be suitably obtained.

Here, the method for producing a toner according to the present invention includes the following steps. (1) A step of producing an aqueous dispersion (A) of resin particles (I) containing a colorant and a polyester resin. (2) The acidic group-containing resin, which becomes self-water dispersible and / or water-soluble by neutralization, is mixed with an aqueous medium in the presence of a basic neutralizing agent and phase-inverted and emulsified to obtain a resin particle (I). A step of producing an aqueous dispersion (B) of fine particles (II) having a small average particle diameter and a high glass transition temperature. (3) A step of uniformly mixing the aqueous dispersion (A) and the aqueous dispersion (B), and precipitating fine particles (II) on the surface of the resin particles (I) with an acid. (4) A step of removing the liquid medium and drying, and taking out the particles having the fine particles (II) deposited on the surface of the resin particles (I) as a dry powder. (5) A step of mixing and stirring the dried powder under heating.

The details of the present invention will be described below.

First, the composition and production method of the resin particles (I) containing a colorant and a polyester resin as essential components will be described below.

The polyester resin may be any resin as long as it can be used as a binder resin for toner, and a known and commonly used polyester resin for toner can be used. Such a polyester resin can be produced by subjecting a polybasic acid and a polyhydric alcohol to dehydration polycondensation in the presence of a catalyst. A portion of the polybasic acid may be subjected to demethanol polycondensation using its methyl esterified product, which is one of its ester-forming derivatives.

Examples of polybasic acids include terephthalic acid,
Aromatic carboxylic acids such as isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, maleic anhydride, fumaric acid, succinic acid,
Examples include aliphatic carboxylic acids such as alkenyl succinic anhydride and adipic acid, and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. One or more of these polybasic acids can be used.

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, butanediol,
Hexanediol, neopentyl glycol, aliphatic diols such as glycerin, cyclohexanediol,
Examples include alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A, aromatic diols such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A. One or more of these polyhydric alcohols can be used.

The glass transition temperature of the polyester resin is 35.
To 75 ° C., more preferably 40 to 6 ° C.
0 ° C. If the glass transition temperature is less than 35 ° C., the heat-resistant storage stability of the toner becomes insufficient, and if it exceeds 75 ° C., the fixability becomes insufficient, which is not preferable.

The content of the acid group of the polyester resin is determined by the mixing ratio of the polybasic acid and the polyhydric alcohol and the reaction rate.
It can be adjusted by controlling the terminal carboxyl group of the polyester. Alternatively, a polyester having a carboxyl group in the main chain can be obtained by using trimellitic anhydride as the polybasic acid component. The content of the acid group of the polyester resin is 1 as an acid value.
３０30 mg · KOH / g is preferred.

The weight average molecular weight of the polyester resin is 2,2.
000 to 200,000, preferably 10,000
It is more preferably from 00 to 150,000 from the viewpoint of fixability and the like.
When the content is within this range, the toner binder has excellent fixability, and also has excellent hue and gloss due to sharp melt properties, so that it can be suitably used as a full-color toner.

In the present invention, it is preferable to use all the polyester resins as described above (100% by weight) as the binder resin, but if necessary, other resins may be added if the amount is less than 40% by weight. Is also good. Such materials include, for example, styrene acrylic resin, urethane resin, epoxy resin, styrene butadiene resin, petroleum resin and the like. Even in such a case, it is preferable to use the binder resin having a weight average molecular weight of 2,000 to 200,000.

As the colorant used in the present invention, any achromatic or chromatic colorant conventionally used in the field of electrophotography can be used, and the following can be exemplified.

Examples of the black pigment that can be used in the black toner include carbon black, cyanine black, aniline black, ferrite, and magnetite. Alternatively, the following chromatic pigments prepared so as to be black can be used.

Examples of the yellow pigment that can be used in the yellow toner include, for example, graphite, zinc yellow, cadmium yellow, yellow iron oxide, loess, titanium yellow, naphthol yellow S, Hansa yellow 10G, Hansa yellow 5G, and Hansa yellow G. , Hanza Yellow GR, Hanza Yellow A, Hanza Yellow RN, Hanza Yellow R, Pigment Yellow L, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG, Vulcan First Yellow 5G, Vulcan First Yellow R, Quinoline Yellow Lake, Anslagen Yellow 6GL, Permanent Yellow FGL,
Permanent yellow H10G, permanent yellow HR, anthrapyrimidine yellow, other isoindolinone yellow, chromophthal yellow, novo palm yellow H2G, condensed azo yellow, nickel azo yellow, copper azomethine yellow, and the like.

Examples of red pigments that can be used in magenta toner include red graphite, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induslen brilliant orange RK, induslen brilliant orange GK, benzidine orange G, Permanent Red 4R, Permanent Red BL, Permanent Red F5RK, Risor Red, Pyrazolone Red, Watching Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Brilliant Carmine 3B, Rhodamine Lake B, Alizarin Lake, Permanent Carmine FB
B, verinone orange, isoindolinone orange, anthranthrone orange, pyranthrone orange, quinacridone red, quinacridone magenta, quinacridone scarlet, perylene red and the like.

Examples of blue pigments that can be used in the cyan toner include cobalt blue, cerulean blue, alkali blue lake, peacock blue lake,
Fanatone Blue 6G, Victoria Blue Lake, metal-free phthalocyanine blue, copper phthalocyanine blue,
Fast Sky Blue, Indazulene Blue RS, Indazulene Blue BC, Indiko, and the like.

The amount of the colorant used is 3 to 50 parts by weight, preferably 3 to 15 parts by weight, per 100 parts by weight of the binder resin.
Parts by weight.

The resin particles (I) preferably contain, as a release agent, a wax or the like commonly used for toner, a metal soap, a lubricant such as zinc stearate, etc. In particular, the wax ensures good fixability. It is effective for Examples of such wax include polyethylene wax, polypropylene wax, paraffin wax, carnauba wax, rice wax and the like. If necessary, the resin particles (I) may contain a charge control agent.

The method for producing the resin particles (I) may be any method and is not particularly limited. However, the effect of the present invention is remarkable because the phase inversion emulsification method as described below easily obtains small particles and spherical particles. It is preferable because it can be expressed in Among them,
The phase inversion emulsification method without using an emulsifier or a dispersant is particularly suitable in terms of operability, environmental stability of charging, and the like.

The method of producing the resin particles (I) by the phase inversion emulsification method without using an emulsifier or a dispersant means a mixture containing an acidic group-containing binder resin which becomes self-water dispersible by alkali neutralization and a colorant as essential components. Is mixed with an aqueous medium (water or a liquid medium containing water as a main component) in the presence of a basic neutralizing agent, followed by phase inversion emulsification to obtain particles containing a colorant.
For example, as disclosed in Japanese Patent Application Laid-Open No. 10-319639, a mixture containing a binder resin and a colorant as essential components is dissolved and dispersed in a hydrophobic organic solvent, and the presence of a basic neutralizing agent is determined. The binder resin is heated and melted without using an organic solvent, as described in US Pat. No. 5,843,614. There is a method of forming colored particles by mixing with an aqueous medium in the presence of a wetting agent. Resin particles (I) of the present invention
Any of these methods can be suitably used.

The aqueous medium used in the present invention refers to a liquid medium containing only water or water as a main component.

In the present invention, the resin capable of becoming self-water dispersible by alkali neutralization is defined as a functional group (acidic group) in the molecule, which can increase hydrophilicity by neutralization, under the action of an aqueous medium. And a resin having the ability to form a stable aqueous dispersion or aqueous solution without substantially using an emulsifier or a dispersion stabilizer. Since the degree of hydrophilicity can be appropriately adjusted by the degree of neutralization (neutralization rate), it is preferable to set the neutralization rate to such an extent that the resin itself can be dispersed in water. By mixing such a self-water-dispersible resin and an organic solvent solution containing a colorant as a main component with an aqueous medium, or by mixing the self-water-dispersible resin itself with an aqueous medium while being heated and dissolved, Phase emulsification occurs,
Particles are formed. At this time, the size of the particles in phase inversion emulsification is determined by the degree of hydrophilicity of the resin,
Arbitrary particle size can be easily obtained by controlling the neutralization ratio.

Examples of the acidic functional group which the resin has and which can increase the hydrophilicity by neutralization include a carboxyl group, a phosphoric acid group, a sulfonic acid group and a sulfuric acid group. Among them, a carboxyl group is preferable. The appropriate neutralization ratio for the resin to exhibit self-water dispersibility or water solubility differs for each resin because the hydrophilicity of the resin itself varies depending on the monomer composition, molecular weight, and the like.

As the neutralizing agent used in the present invention, first, a basic neutralizing agent is used to convert the acidic group-containing resin into a self-water dispersing agent. An acidic neutralizing agent is used to return the converted acidic group-containing resin to the original acidic group. Examples of the basic neutralizer include inorganic metal salts such as sodium hydroxide, potassium hydroxide and lithium hydroxide; inorganic alkalis such as ammonia; and alkanolamines such as monoethanolamine and diethanolamine, dimethylamine and diethylamine. Secondary amines, tertiary amines such as triethylamine, and organic amines such as hydrazine, and examples of the acidic neutralizing agent include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, oxalic acid, formic acid, acetic acid, and succinic acid. And organic acids such as p-toluenesulfonic acid.

When a water-insoluble resin which does not disperse itself in water, that is, has no self-water dispersibility, is used as the binder resin of the resin particles (I), the resin solution and / or an aqueous medium mixed therewith It is necessary to add and use an emulsifier and / or a dispersion stabilizer.

As such a dispersion stabilizer, a water-soluble polymer compound is preferable, for example, polyvinyl alcohol,
Polyvinyl pyrrolidone, hydroxyethyl cellulose,
Carboxymethyl cellulose and the like can be mentioned. Examples of the emulsifier include various nonionic surfactants such as polyoxyethylene alkylphenol ether, and various anionic or cationic surfactants such as sodium alkylbenzenesulfonate. Of course, two or more kinds of emulsifiers may be used in combination, two or more kinds of dispersion stabilizers may be used in combination, or an emulsifier and a dispersion stabilizer may be used in combination. It is common to use an emulsifier in combination.

When such an emulsifier or dispersion stabilizer is used, its concentration in the aqueous medium is suitably adjusted to about 0.5 to 3% by weight.

Further, even when a resin which can be made self-water dispersible by neutralization as described above is used, if necessary, the emulsifier and / or the dispersion can be stabilized as long as the effects of the present invention are not impaired. Agents may be used.

When an organic solvent is used for phase inversion emulsification, it is convenient to prepare an aqueous slurry in which the organic solvent has been removed from the liquid medium after phase inversion emulsification before proceeding to the next step. When the self-water dispersible resin as described above is used for the resin particles (I), the organic solvent was removed from the liquid medium after the phase inversion emulsification, the aqueous slurry was separated by filtration, and the wet cake was washed. Thereafter, it is preferable to return the salt portion contained in the acidic group-containing resin to the original acidic group with an aqueous acid solution. The volume average particle size of the resin particles (I) is 3 to 15 μm in order to improve image quality when used as a toner.
Particularly, 3 to 8 μm is preferable.

Next, the deposition and fixation of the acidic group-containing resin on the surface of the resin particles (I) will be described. This is an aqueous dispersion (A) of the resin particles (I) obtained by the method described above.
The resin particles (I) obtained by mixing an acidic group-containing resin, which becomes self-water dispersible and / or water-soluble by neutralization, with an aqueous medium in the presence of a basic neutralizing agent and phase inversion emulsification, An aqueous dispersion (B) of fine particles (II) having a small average particle diameter and a high glass transition temperature is uniformly mixed, and fine particles (II) are precipitated on the surface of the resin particles (I) with an acid. Is removed, and the dried powder is stirred and mixed under heating to obtain a toner having an acidic group-containing resin fixed on the surface.

As the acidic group-containing resin which can be used for the fine particles (II) and becomes self-water dispersible and / or water-soluble by neutralization,
Although not particularly limited, a styrene (meth) acrylic resin or a polyester resin containing an acidic group is preferable because good negative chargeability is easily obtained.

The acidic group-containing styrene (meth) acrylic resin which can become self-water dispersible by neutralization includes a radical polymerizable monomer containing an acid group and a radical polymerizable monomer containing the acid group. Other radical polymerizable monomers,
Those obtained by radical polymerization in the presence of a polymerization initiator can be used. The polymerization reaction for obtaining these can be suitably used in solution polymerization, suspension polymerization and emulsion polymerization.

Examples of such acidic group-containing polymerizable monomers include acrylic acid, methacrylic acid, crotonic acid,
Examples include itaconic acid, maleic acid, fumaric acid, monobutyl itaconate, monobutyl maleate and the like.

Examples of the polymerizable monomers other than the acidic group-containing polymerizable monomers include, for example,

(1) Styrene monomer: styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene or chlorostyrene

(2) Acrylates: methyl acrylate, ethyl acrylate, isopropyl acrylate,
N-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-acrylate
-Hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate or dodecyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, alpha-methyl methyl acrylate

(3) Methacrylates: methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-methacrylate Octyl, decyl methacrylate, dodecyl methacrylate, 2-chloroethyl methacrylate, phenyl methacrylate, alpha chloromethyl methacrylate

(4) acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide;

(5) Vinyl ether: vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether,

(6) Vinyl ketone: vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone

(7) N-vinyl compound: N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like can be mentioned.

In the case of obtaining the resin, a general-purpose organic solvent can be used in the case of solution polymerization. Examples of the organic solvent used include various hydrocarbons such as toluene, xylene, benzene, n-hexane, cyclohexane and n-heptane; methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, sec- Alcohols such as butanol and t-butanol; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monoisopropyl ether, propylene glycol mono n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether; Ether alcohols such as ethylene glycol mono n-butyl ether; acetone, methyl ethyl ketone, Various ketones such as butyl isobutyl ketone; various esters such as ethyl acetate, butyl acetate and isobutyl acetate; various ether esters such as propylene glycol monoethyl ether acetate and ethylene glycol monoethyl ether acetate; various cyclic ethers such as tetrahydrofuran Various organic solvents such as various halogenated hydrocarbons such as methylene chloride;

As the polymerization initiator to be used, various known and commonly used organic peroxide-based initiators and azo-based initiators can be used. Specifically, for example, peroxides such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, sodium persulfate and ammonium persulfate, and azo-based compounds such as azobisisobutyronitrile and azobisisovaleronitrile Compounds.

The acid group-containing styrene acrylic resin used for the fine particles (II) includes an acid value of 30 to 150 (mgK
OH / g), a weight average molecular weight of about 6,000 to 300,000, and a glass transition temperature which is preferably higher than that of the resin particles (I) in order to ensure heat-resistant storage stability.
The fine particles (II) may contain a charge control agent, wax, or the like, if necessary.

The amount of the fine particles (II) added to the surface of the resin particles (I) is 0.05 to 10% by weight, more preferably 0.1 to 6% by weight, based on the resin particles (I). If the addition amount is too large, the charge amount becomes too high and the stability over time of the charge tends to decrease, which is not preferable.

In the present invention, the organic solvent used for producing the resin particles (I) or the fine particles (II) by phase inversion emulsification includes:
Any organic solvent may be used as long as it dissolves the resin used. Further, the organic solvent used in the resin synthesis may be used as it is. As described above, for example, toluene,
Aromatic hydrocarbon solvents such as xylene and benzene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ether solvents such as tetrahydrofuran, and halogen solvents such as carbon tetrachloride, trichloromethane and dichloromethane are used. In this case, for example, the combined use of a water-soluble or partially water-soluble organic solvent such as acetone, butanol, or isopropyl alcohol facilitates the generation of particles in phase inversion emulsification. Preferably, the use of so-called low-boiling solvents, such as acetone, methyl ethyl ketone or ethyl acetate, tetrahydrofuran, which can be easily removed, is suitable.

The water slurry of the fine particles (II) is obtained by the same operation as the water slurry of the resin particles (I) before the reverse neutralization.
The average particle diameter of the fine particles (II) must be smaller than that of the resin particles (I), and is 10 nm to 1 μm, particularly preferably 10 to 100 nm.

The fine particles (II) are deposited on the surface of the resin particles (I) by uniformly mixing the aqueous dispersion of the resin particles (I) and the fine particles (II), and stirring the mixture with an acidic neutralizing agent. In addition, the process is performed by returning the fine particles (II) to the original non-neutralized (unneutralized) acidic groups. This is because the acid neutralization lowers the hydrophilicity of the fine particles (II), so that the fine particles (II) are precipitated on the surface of the resin particles (I). In this case, if the precipitation speed of the fine particles (II) is too high, the fine particles aggregate, and not only does not uniformly precipitate on the surface of the resin particles (I), but also the resin particles (I) aggregate. Not preferred. Here, if a metal salt such as calcium chloride is added, it is possible to prevent rapid precipitation due to dropping of an acid. This precipitation step is generally performed under stirring, and the stirring blade is not particularly limited, but a stirring blade such as a Faudler blade having a small air entrapment is preferable.

The acidic neutralizing agent used for the precipitation is added until the pH of the slurry becomes 2 to 5 and adjusted to a predetermined pH, followed by stirring for about 30 minutes to remove the fine particles (II) from the resin particles. Completely adhere to the surface of (I).

The resin particles (I) having the fine particles (II) adhered to the surface are separated by filtration from a liquid medium by a centrifuge or the like to obtain a wet cake of toner particles. The wet cake may be dried by any known and commonly used drying method. For example, the wet cake may be dried by heating at a temperature at which the toner particles do not fuse or aggregate, or may be freeze-dried. There is also a method in which separation and drying of toner particles from an aqueous medium and drying are performed simultaneously using a continuous instantaneous air-flow dryer or a spray dryer.

The resin particles (I) having the fine particles (II) adhered to the surface are dried and then mixed under heating using a known and commonly used powder mixing mixer such as a Henschel mixer or a hybridizer. Stabilize and equalize the surface. Stirring and mixing for about 5 to 60 minutes while heating to a temperature range (for example, about 60 ° C.) at which aggregation of toner particles does not occur promotes stabilization and homogenization of the acidic group-containing resin fixed on the particle surface, This treatment step is an important element of the production method of the present invention, because the stability with time of charging and the like is significantly improved as a result.

As the particle size of the toner particles used in the present invention, any size can be selected within a practical level as a toner. From the point of matching with the current machine, it is preferable that the volume average particle diameter is in the range of 3 to 15 μm. In particular, a small particle size toner having a volume average particle size of about 3 to 8 μm is preferable because it is excellent in image quality such as resolution and gradation.

In general, inorganic fine particles are externally added to the toner particles obtained by the above method in order to secure fluidity and chargeability appropriate as an electrostatic image developer. Such inorganic fine particles include silica, titanium oxide, alumina,
Examples include barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide, and silicon nitride. The external addition amount of these inorganic fine particles is about 0.1 to 5% by weight, particularly preferably about 0.1 to 3% by weight, based on the toner particles. In the negatively chargeable toner of the present invention, various kinds of organic fine particles may be used in addition to such inorganic fine particles.

The toner of the present invention can be used as a non-magnetic one-component developer or a magnetic one-component developer, or can be used as a two-component developer by combining with a carrier. In addition to the above, a high quality image can be obtained due to good expression of charging characteristics.

As the carrier, any known and commonly used carriers can be used. For example, iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and other metals and their alloys or oxides, surface-treated glass, powders of silica, etc. can be used, and their acrylic resin coated carriers,
Resin-coated carriers such as silicone resin-coated carriers, fluororesin-coated carriers, and fluorine / acrylic resin-coated carriers are more suitable for use in the toner of the present invention. The average particle size of the carrier is not particularly limited,
Those having a size of about 20 to 200 microns are preferably used.

[0069]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments.

1. A toner in which an acidic group-containing resin is fixed on the surface of resin particles (I) containing a colorant and a polyester resin as essential components.

2. 2. The toner according to the above item 1, wherein the acidic group of the resin fixed on the surface is a carboxyl group.

3. 3. The above-mentioned 1 or 2, wherein the average circularity (the average value of the circularity defined by (perimeter of a circle having the same area as the particle projection area) / (perimeter of the particle projection image)) is 0.97 or more. Toner.

4. An aqueous dispersion of the resin particles (I) is obtained by mixing an acidic group-containing resin which becomes self-water dispersible and / or water-soluble by neutralization with an aqueous medium in the presence of a basic neutralizing agent and phase inversion emulsification. An aqueous dispersion of fine particles (II) having a smaller average particle diameter and a higher glass transition temperature than the resin particles (I) is uniformly mixed, and the fine particles (I) are applied to the surface of the resin particles (I) with an acid.
2. The method for producing a toner according to the above item 1, wherein the toner is obtained by precipitating I), removing the liquid medium therefrom, drying the dried powder, and stirring and mixing the dried powder under heating.

5. A mixture containing an acidic group-containing polyester resin whose resin particles (I) become self-water dispersible by neutralization and a colorant as essential components is mixed with an aqueous medium in the presence of a basic neutralizing agent, and phase-inverted and emulsified. 5. The method according to the above item 4, wherein the particles are particles obtained by encapsulating a colorant.

[0075]

The present invention will be described in more detail with reference to resin synthesis examples, examples, and comparative examples. In the following:
“Parts” and “%” represent “parts by weight” and “% by weight”, respectively, and “water” means “deionized water”.

(Preparation of Fine Particle (II) Water Slurry) Methyl ethyl ketone 114 parts, isopropyl alcohol 12
Parts and 24 parts of water were placed in a reaction vessel and heated to 80 ° C., and then a mixture having the following ratio was charged at once in a nitrogen stream to start the reaction. Acrylic acid 54.0 parts Styrene 364.8 parts Butyl acrylate 181.2 parts "Perbutyl O" 0.6 parts

After 3 hours from the start of the reaction, every hour,
About 10 parts of the reaction resin solution was sampled, diluted with the same amount of methyl ethyl ketone, and the viscosity was measured with a Gardner viscometer. When the viscosity became MN, a mixed solvent consisting of 567 parts of methyl ethyl ketone and 63 parts of isopropyl alcohol was added. At this time, the residual ratio of the monomer was quantified by using gas chromatography, and the polymerization ratio was calculated to be 51%. After the temperature of the reaction solution was heated to 80 ° C., a mixture having the following ratio was added dropwise over 1 hour. Acrylic acid 54.0 parts Styrene 456.6 parts Butyl acrylate 89.4 parts "Perbutyl O" 18.0 parts

After completion of the dropwise addition, 2 parts of “perbutyl O” were added three times every three hours, and the reaction was continued for another four hours.
After the completion of the reaction, the resin solution was degassed by heating to perform a solidification treatment. This solidified resin has a molecular weight distribution of two peaks,
Its weight average molecular weight was 110,000. Also,
When these two peaks are separated at the boundary, the weight average molecular weight is 3
Can be split into two parts, 5,000 and 360,000,
The ratio was 78:22. This solidified resin had an acid value of 70 and a glass transition temperature of 70 ° C.

A reaction vessel was charged with 750 parts of a solution obtained by dissolving 300 parts of the carboxyl group-containing styrene acrylic resin obtained above in 450 parts of methyl ethyl ketone, and 150 parts of a 1N aqueous sodium hydroxide solution.
The resulting emulsion was phase-inverted and emulsified by dropping water to obtain a dispersion of fine resin particles having a volume average particle diameter of 0.1 μm or less. After further stirring for 20 minutes, the solvent was removed by vacuum distillation to obtain a water slurry of fine particles (II) having a slurry concentration of about 30%.

(Preparation of Water Slurry of Black Resin Particles (I)) Polyester resin 6 having an acid value of 8, a weight average molecular weight of 7,000, a number average molecular weight of 3,400 and a glass transition temperature of 58 ° C.
96 parts, an acid value of 10, a weight average molecular weight of 122,000, a number average molecular weight of 5,500, a glass transition temperature of 60 ° C., 1044 parts of a polyester resin, 200 parts of Elftex 8 (carbon black manufactured by Cabot), and 60 parts of carnauba wax No. 1 After that, the resultant was dissolved and dispersed in 2000 parts of methyl ethyl ketone to adjust the nonvolatile content to 50%.

To 240 parts of this pigment dispersion resin solution, 1
After 7 parts of a normal ammonia aqueous solution and 60 parts of methyl ethyl ketone were added and uniformly stirred with a homomixer, the rotation speed of the apparatus was increased to 12000 rpm, and 300 parts of water was added to perform phase inversion emulsification. Further, after stirring was continued for 10 minutes at the same rotation speed, a dispersion of colored resin particles was obtained. Thereafter, the organic solvent was removed by vacuum distillation to remove the organic solvent, and then water was added so that the slurry concentration became about 20%, to obtain an aqueous dispersion of the resin particles (I). After filtration and washing with water, water was added to the filtered water-containing cake to obtain a water slurry containing 20% of resin particles (I) having a volume average particle size of 6.8 μm. The resin particles (I) were spherical with an average circularity of 0.985.

(Preparation of Water Slurry of Cyan, Magenta and Yellow Resin Particles (I)) Acid Value 8, Weight Average Molecular Weight 7
000, number average molecular weight 3400, glass transition temperature 58 ° C
736 parts of a polyester resin having an acid value of 10, a weight average molecular weight of 122,000, a number average molecular weight of 5,500, a polyester resin having a glass transition temperature of 60 ° C. 1104 parts, Carnauba wax No. 1 60 parts, and a phthalocyanine pigment Ket Blue 123 instead of carbon black pigment. (Kinacridone pigment toner magenta E-02 (manufactured by Hoechst Industries) and Disazo Pigment Ket Yellow 403 (manufactured by Dainippon Ink and Chemicals)) were kneaded using 100 parts each, and then mixed with 2000 parts of methyl ethyl ketone. It was dissolved and dispersed to adjust the nonvolatile content to 50%. Then, in the same manner as in the preparation of the water slurry of the black resin particles (I),
A water slurry having a volume average particle size of 6.5 to 7.0 μm and containing 20% of spherical resin particles (I) of cyan, magenta, and yellow was obtained. The average circularity of these resin particles (I) was spherical from 0.984 to 0.987.

Example 1 1000 parts of the water slurry of the black resin particles (I) prepared above and 150 parts of the water slurry of the fine particles (II) (solid content: 45 parts) were charged into a reaction vessel and stirred at 0. 1% calcium chloride aqueous solution 150
Then, 350 parts of 1 N hydrochloric acid was added to adjust the pH of the slurry to 2.5, and the fine particles (II) were precipitated on the surface of the resin particles (I). This was filtered and washed with water, and then dried at about 40 ° C. using a vacuum mixing dryer to obtain powder particles.
Next, this powder was placed in a Henschel mixer and stirred and mixed for about 10 minutes while maintaining the jacket temperature at 70 ° C., to obtain toner particles having fine particles (II) firmly fixed on the surface.

This is a sphere with an average circularity of 0.984, and S
Observation with an EM (scanning electron microscope) revealed fine irregularities on the surface. 1.5 parts of hydrophobic silica (RY200 manufactured by Nippon Aerosil) and 0.5 part of titanium oxide (MT-150 manufactured by Teica) were externally added to 100 parts of the toner particles using a Henschel mixer to obtain a black toner.

(Examples 2, 3 and 4) In the same manner as in Example 1, cyan, magenta and yellow toners were obtained. These were spherical toners having an average circularity of 0.984 to 0.986.

(Comparative Examples 1, 2, 3 and 4) A water slurry of the above-prepared resin particles (I) of black, cyan, magenta and yellow was charged into a reaction vessel, and 1N hydrochloric acid was added with stirring. Then, the slurry was adjusted to pH 3, filtered, washed with water, and dried using a vacuum mixing dryer to obtain powder particles. Next, the powder particles were subjected to the same external addition as in Example 1 (no high-Tg acidic group-containing resin was fixed on the surface) to obtain black, cyan, magenta and yellow toners.

The following tests were performed on the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 4.

(Development Test) Examples 1-4 and Comparative Examples 1-4
Each toner obtained in the above was filled in a toner cartridge of a one-component developing system printer (Epson LP-1700), and an image output test was performed. As a result, all were excellent in resolution, gradation, hue, gloss, and the like. A printed image was obtained. In particular, high T
g of the toner having the acidic group-containing resin fixed on the surface. This is because the toner having the resin adhered to the surface has fine irregularities on the surface, so that a better triboelectric charging property can be obtained as compared to a spherical toner having no such treatment and having a smoother surface. I guess.

(Fixing Test) A commercially available copying machine (manufactured by Ricoh Company)
An unfixed image is formed using a modified machine of IMAGIO MF530, and a modified fixing device of the same machine is used to control the paper feed speed to 120 mm / sec. And the fixing temperature was examined.

The determination of the fixing property was performed by using “Scotch Mending Tape” manufactured by Sumitomo 3M Limited on the toner image.
, And after a weight of 100 g / cm ² was applied thereto, the film was slowly peeled off, and the change in image density was measured using a Macbeth densitometer. Using a solid image having an image density of 1.4 to 1.6, the minimum temperature of the hot roll at which the ratio of the image density before and after the mending tape peeling test becomes 90% or more is defined as the fixing start temperature, and the hot roll at which hot offset occurs. The fixing temperature range was determined using the minimum temperature of the above as the fixing upper limit temperature.

The toners of Examples 1 to 4 all have a fixing temperature range of 110 to 180 ° C., and the toners of Comparative Examples 1 to 4 all have a fixing temperature of 110 to 175 ° C. Showed sex.

(Heat-resistant Storage Stability) Each toner was placed in a glass sample bottle, allowed to stand at 50 ° C. for 7 days, returned to room temperature, and evaluated by the degree of aggregation of particles. No aggregation was observed in any of the toners of Examples 1 to 4, but Comparative Examples 1 to 4.
Aggregation occurred in each of the toners of No. 4 and No. 4.

From the above evaluation results, it was found that the toners of the respective examples in which the high-Tg acidic group-containing resin was fixed on the surface of the colored particles having the polyester resin as the binder resin had excellent low-temperature fixability and heat-resistant storage stability. It can be seen that it has.

[0094]

According to the present invention, by fixing an acidic group-containing resin having a higher glass transition temperature than the binder resin of the colorant-containing polyester resin particles to the surface of the colorant-containing polyester resin particles, excellent low-temperature fixability and heat resistance are obtained. A toner having both storability is obtained. A spherical toner using such a polyester resin as a binder resin can obtain good chargeability without using a charge control agent, and also has excellent image quality such as resolution, gradation, hue, and gloss. ing. As a production method suitable for the present toner, a method of fixing an acidic group-containing resin to the surface of spherical colored particles using a polyester resin as a binder resin is disclosed.

Claims (5)

[Claims] 1. A toner comprising a resin particle (I) containing a colorant and a polyester resin as essential components, and an acidic group-containing resin fixed on the surface of the resin particles (I). 2. The method according to claim 1, wherein the acidic group is a carboxyl group.
The toner described in the above. 3. A spherical shape having an average circularity (average circularity defined by (perimeter of a circle having the same area as the projected area of a particle) / (perimeter of a projected image of a particle)) of 0.97 or more. The toner according to claim 1. 4. An aqueous dispersion (A) of resin particles (I) is mixed with an aqueous medium containing an acidic group-containing resin which becomes self-water dispersible and / or water-soluble by neutralization in the presence of a basic neutralizing agent. An aqueous dispersion (B) of fine particles (II) having a smaller average particle diameter and a higher glass transition temperature than the resin particles (I) obtained by mixing and phase-inversion emulsification is uniformly mixed, and the resin particles (I) are acid-mixed. 2. The method for producing a toner according to claim 1, wherein fine particles (II) are precipitated on the surface of (1), the liquid medium is removed therefrom, and dried, and the dried powder is obtained by stirring and mixing under heating. 5. A mixture comprising an acidic group-containing polyester resin whose resin particles (I) become self-water dispersible by neutralization and a colorant as essential components is mixed with an aqueous medium in the presence of a basic neutralizer. The production method according to claim 4, wherein the particles are particles containing a colorant, which are obtained by phase inversion emulsification.