JPH0943901A - Manufacture of electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner which is excellent in environmental stability by suppressing the environmental variation of toner characteristics obtained by emulsion polymerization or suspension polymerization using such a monomer composition that forms a binder resin which is liable to be affected by the environmental variation and contains an acid radical. SOLUTION: A toner uses colorant, monthlyene polymerization monomer containing an acid radical, and dispersion stabilizer as essential components. Also it is polymerized in a monomer insoluble solvent under the presence of polymerization initiator that is insoluble in liquid medium and soluble in monomer. Then the dispersing liquid of toner particles which is formed with the polymer of a monomer containing colorant and insoluble in liquid medium can be obtained. In addition, ammonia or organic amine is added to it so as to neutralize the acid radical in the polymer. The liquid medium is then removed from it and electrophotographic toner is produced from a drying process. Thus the electrophotographic toner with such toner characteristics that is excellent in powder fluidity and environmental stability can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dry toner composition for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art In electrophotography, dry developers are roughly classified into one-component developers using a toner itself in which a colorant is dispersed in a binder resin and two-component developers in which the toner and a carrier are mixed. can do.

In any case, when copying, the electrostatic latent image formed on the photoconductor is developed with these developers, and the toner powder imaged on the photoconductor is transferred to a transfer material such as paper or sheet. The image is fixed using heat, pressure, etc. to obtain a permanent image. At that time, in order to obtain a permanent image with sufficient image density and high resolution, it is necessary to adhere a predetermined amount of toner powder to the electrostatic latent image formed on the photoconductor faithfully to the latent image. .

Therefore, for practical toners, a characteristic that a sufficient amount of charge is rapidly developed by friction, and an environmental stability characteristic that the amount of charge can be reproduced almost the same under high temperature and high humidity or low temperature and low humidity conditions, etc. The so-called charging characteristic of is an important design factor. In addition, since it is necessary to be provided for development as individual particles rather than as agglomerates, fluidity is secured or powder environmental stability is ensured against changes in temperature and humidity. Toners are required to have many functions such as prevention of hot offset which induces image stain.

In recent years, a polymerization method toner has been attracting attention as a toner whose usage amount is increasing more and more as an image forming material for a copying machine, a laser printer and the like.

In the conventional toner manufacturing method, a mixture of a binder resin and a coloring agent is kneaded while being melted by a heating mixer, cooled, and then mechanically pulverized and finely pulverized by a pulverizer such as a jet mill. A method is generally used in which toner particles are classified to obtain toner particles, and if necessary, an external additive is mechanically mixed (dry method), and the particle shape is an angular polyhedral shape like crushed ice. It was characterized by that.

On the other hand, a toner produced by a polymerization method typified by suspension polymerization or emulsion polymerization is completely different from a conventional mechanical pulverization method, and for example, is mixed with a binder resin in the presence of a colorant in an aqueous medium. This is a method of chemically reacting a monomer to be synthesized to synthesize a binder resin and, at the same time, granulating particles containing a colorant, and toner particles are manufactured in one step.

A major characteristic of this polymerization toner is
It is difficult to obtain by a dry process, and it is possible to make a toner shape substantially spherical and to easily manufacture a uniform particle toner having a sharp particle size distribution. Such a spherical toner offers the advantage of being able to design a small particle size toner having excellent powder flowability, and is expected to develop into a high-performance toner that matches the market demand for high image quality and high resolution. There is.

In the toner utilizing such emulsion polymerization or suspension polymerization, from the viewpoint of avoiding environmental changes to the toner properties such as hygroscopicity, it is originally a binder resin containing an acidic group. Generally, no monomer composition is adopted.

[0010]

SUMMARY OF THE INVENTION The present invention is based on an environment of toner characteristics obtained by emulsion polymerization or suspension polymerization with a monomer composition which is a binder resin containing an acidic group, which is originally susceptible to environmental changes. It seeks to control fluctuations by other technical means.

As a common problem of these emulsion polymerization method and suspension polymerization method toners, there is a problem that it is difficult to obtain stable charging characteristics as obtained by a conventional dry method toner by mechanical pulverization. Specifically, in the friction with a carrier or a blade which is usually used in a copying machine or a laser printer, a sufficient charge amount cannot be expressed in the toner, or even if an appropriate charge amount can be given. There is a problem that the rising speed is slow, and further, the charge amount largely changes due to environmental changes such as temperature and humidity, so that stable high quality images cannot be obtained.

In view of the above circumstances, the present invention provides a method for producing a toner having excellent charging characteristics. More specifically, the present invention provides a method for producing a toner, which is obtained by suspension polymerization or emulsion polymerization. An object of the present invention is to provide a method for producing a dry toner having a structure in which ammonia or an organic amine compound is attached by ionic bond and capable of stably printing a large number of sheets on a high quality image.

[0013]

As a result of intensive studies, the inventors of the present invention have solved the above problems. That is, the present invention is as follows.

A colorant, a monoethylenically polymerizable monomer containing an acid group, and a dispersion stabilizer are contained as essential components in a liquid medium in which the monomer is insoluble and insoluble in the liquid medium and in the unit amount. Polymerization in the presence of a body-soluble polymerization initiator to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which comprises a polymer of the monomer including a colorant, ammonia or Second step of adding an organic amine to neutralize the acid groups in the polymer, and then removing the liquid medium and drying the third step
A method for producing an electrophotographic toner (1st invention) comprising steps.

A colorant and a monoethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine are essential components and are insoluble in the liquid medium in which the monomer is insoluble. Polymerization is performed in the presence of a polymerization initiator soluble in the monomer to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is a polymer of the monomer including a colorant.
A method for producing an electrophotographic toner, which comprises a step, and then a second step of removing a liquid medium therefrom and drying (second invention).

A colorant and a monoethylenically polymerizable monomer containing an acid group are used as essential components, and they are ultrasonically dispersed to obtain a monomer-insoluble liquid medium which is insoluble in the liquid medium. Polymerization is performed in the presence of a polymerization initiator soluble in the monomer to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer including a colorant. A method for producing an electrophotographic toner, which comprises a second step of adding ammonia or an organic amine to neutralize the acid groups in the polymer, and then a third step of removing the liquid medium therefrom and drying (third invention).

Polymerization is carried out in an aqueous medium in the presence of a water-soluble polymerization initiator with a colorant, a monoethylenically polymerizable monomer having an acid group, and an emulsifier as essential components, and the colorant is included. A first step of obtaining a dispersion of the toner particles insoluble in the aqueous medium, which comprises a polymer of the monomer, and a second step of adding ammonia or an organic amine thereto to neutralize the acid groups in the polymer, Next, a method for producing a toner for electrophotography, which comprises a third step of removing the aqueous medium and drying it (the fourth invention).

Polymerization in the above aqueous medium in the presence of a water-soluble polymerization initiator, with a colorant and a monoethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine as essential components. For electrophotography, which comprises the first step of obtaining a dispersion of the toner particles insoluble in the aqueous medium, which is made of a polymer of the monomer containing a colorant, and then a second step of removing the aqueous medium and drying. Toner manufacturing method (fifth invention).

The toner particles obtained by the production method of the present invention are particles containing, as essential components, a colorant and a binder resin produced by radical polymerization of an ethylenically polymerizable monomer. The binder resin containing the agent dispersed therein contains a functional group having anion forming ability such as a carboxyl group, a phosphoric acid group and a sulfonic acid group, that is, an acid group, and a part of the acidic group is present on the toner particle surface. Is exposed, and a part of the acidic groups is neutralized with ammonia or an organic amine.

Toner particles containing such a colorant, which are anion-formed, that is, whose acid groups are neutralized with ammonia or an organic amine, and which are composed of a binder resin with some functional groups exposed on the surface of the particles, After polymerizing by applying a conventionally known suspension polymerization method or emulsion polymerization method using an ethylenically unsaturated monomer containing an acid group, the acid group is neutralized in the subsequent optional step. Alternatively, it can be obtained relatively easily by applying a conventionally known suspension polymerization method or emulsion polymerization method using ammonia or an organic amine neutralized product of the monomer.

Specifically, for example, in the presence of a dispersion stabilizer or an emulsifier, a colorant and a reactive monomer capable of forming a binder resin are suspended or emulsified and dispersed in a liquid medium to prepare a polymerization initiator. In the presence of the above, the polymerization reaction by radical polymerization is carried out with stirring to obtain a spherical aqueous dispersion of toner particles in which a colorant is encapsulated in a binder resin. The definitions of suspension polymerization and emulsion polymerization are given in the Chemical Dictionary (Morikita Publishing).

A colorant, an ethylenically polymerizable monomer containing an acid group, and a dispersion stabilizer are contained as essential components in a liquid medium in which the monomer is insoluble and insoluble in the liquid medium and the monomer. Is polymerized in the presence of a soluble polymerization initiator to obtain a dispersion of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer containing a colorant, or a colorant and ammonia or An ethylenically polymerizable monomer containing an acid group neutralized with an organic amine is used as an essential component, together with a dispersion stabilizer if necessary, in the monomer-insoluble liquid medium, the liquid medium. Polymerization is performed in the presence of a polymerization initiator insoluble in and soluble in the monomer to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer including a colorant, or , A colorant and an ethylenically polymerizable monomer containing an acid group as essential components The presence of a polymerization initiator insoluble in the liquid medium and soluble in the monomer in the liquid medium in which the monomer is insoluble, by mixing or dispersing them with ultrasonic waves and using a dispersion stabilizer as necessary. Polymerization is performed under the following conditions to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer including a colorant. That is, the production of the toner particle dispersion liquid by the suspension polymerization in the invention. Is the way.

On the other hand, a colorant, an ethylenically polymerizable monomer containing an acid group, and an emulsifier are used as essential components, and polymerization is carried out in an aqueous medium in the presence of a water-soluble polymerization initiator to obtain the colorant. An aqueous dispersion of insoluble toner particles consisting of a polymer of the above-mentioned monomer is obtained, or a colorant and an ethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine. The body and as an essential component, if necessary in combination with an emulsifier, in the aqueous medium, the polymerization is carried out in the presence of a water-soluble polymerization initiator, and is composed of a polymer of the monomer including a colorant. Obtaining a dispersion of toner particles insoluble in an aqueous medium is the method for producing a dispersion of toner particles by emulsion polymerization in the present invention.

Examples of the monoethylenically polymerizable monomer having an acid group include acrylic acid, methacrylic acid,
Crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid monobutyl, maleic acid monobutyl, acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, 3-chloro-2-acrylamido-2-methylpropanesulfonic acid, 2-sulfo Examples thereof include ethyl methacrylate, and these may be used alone or in combination of two or more kinds.

In the present invention, it is possible to use only at least one kind of monomer selected from the above-mentioned monomers, but in order to improve various properties as a toner, usually, a monomer containing the above-mentioned acid group is used. By copolymerizing an ethylenically polymerizable monomer with another radically polymerizable monomer, a liquid medium containing an acid group such as a carboxyl group, a phosphoric acid group or a sulfonic acid group on the particle surface is formed. It may be a dispersed toner particle dispersion. The compounding ratio of the acid group-containing monomer is 2 to 30% by weight, preferably 10 to 30% by weight based on all the reactive monomers capable of forming the binder resin.
It is 20% by weight.

In the present invention, the charge control agent is not an essential component because the charge characteristic can be controlled by the acid group or the neutralized acid group in the binder resin.

Specific examples of the radically polymerizable monomer copolymerizable with the above-mentioned acid group-containing monomer include styrenes such as styrene, α-methylstyrene, chlorostyrene and vinylstyrene, ethylene, Propylene, butylene, isobutylene and other monoolefins, vinyl acetate,
Vinyl esters such as propion vinyl, vinyl butyrate, vinyl benzoate, methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, phenyl dodecyl acrylate, phenyl methacrylate, methyl methacrylate,
Ethyl methacrylate butyl methacrylate, α-methylene aliphatic monocarboxylic acid esters such as dodecyl methacrylate, ethylene glycol monoacrylate, propylene glycol monoacrylate, glycol mono (meth) acrylic acid ester such as tetramethylene ether glycol monoacrylate, Acrylic monomers such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl propenyl ketone, and the like, and these may be used alone or in combination of two or more. It can be used in combination.

The monomer composition constituting the binder resin is prepared so that the glass transition temperature of the polymer is 40 to 90 ° C, preferably 50 to 80 ° C.

If desired, a small amount of a reactive monomer having two or more ethylenically unsaturated double bonds may be used in combination therewith. Examples of the reactive monomer having two or more ethylenically unsaturated double bonds include conjugated dienes such as butadiene and isoprene, divinylbenzene, di (meth) acrylate of bisphenol A alkylene oxide adduct, and trimethylolpropanetri (meta). A) acrylate, pentaerythritol tetra (meth) acrylate, and the like.

As the polymerization initiator used to obtain such a polymer resin, of course, a usual oil-soluble or water-soluble one can be used. For example, benzoyl peroxide,
Various peroxides such as di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroxide or 2-ethylhexanoate; or various azo such as azobisisobutyronitrile or azobisisovaleronitrile. A compound etc. can be mentioned.

In suspension polymerization, a polymerization initiator insoluble in the liquid medium used for the polymerization and soluble in the monomer is selected as an essential component, and in emulsion polymerization, a water-soluble polymerization initiator is selected as an essential component. used. The amount of the polymerization initiator used is not particularly limited, but is 0.01 to 5 parts by weight per 100 parts by weight of all the reactive monomers (total monomers).

The binder resin formed by polymerization can be arbitrarily adjusted depending on the polymerization conditions and the like, but it is preferable to prepare it so that the weight average molecular weight is 10,000 to 500,000.

As the colorant in the toner particles used in the present invention, known and commonly used colorants can be used. Specifically, for example, carbon black, magnetic powder, nigrosine dye, aniline blue, calcoil blue, chrome yellow. , Ultramarine Blue, DuPont Oil Red,
Quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengara, C.I. I. Pigment Red 122, C.I. I. Pigment Yellow 97, C.I. I.
Pigment Blue 15, ferrosoferric oxide, ferric oxide, iron powder, zinc oxide, selenium, etc. can be used, and they can be used alone or in combination of two or more.

In the present invention, the toner obtained may be magnetic toner particles in which magnetic fine particles are dispersed in a binder resin. As the magnetic substance fine particles, any ferromagnetic substance that is normally used can be used.

Specific examples of the magnetic material include magnetic metals such as iron, cobalt and nickel, alloys thereof, metal oxides such as cobalt-added iron oxide and chromium oxide, Mn / Zn ferrite, Ni / Zn ferrite and the like. Various kinds of ferrite,
In addition to magnetite, hematite, etc., the surface of these, silane coupling agent, aluminum coupling agent,
Powders such as those treated with a surface treatment agent such as a titanium coupling agent or those coated with a polymer can be used.

When carbon black is used as the colorant, it is preferable to use basic carbon black because it is excellent in affinity with the binder resin and a toner having good charging characteristics can be obtained.

The weight ratio of the colorant and the binder resin is not particularly limited, but it is preferable that the colorant is 3 to 30% by weight when the total weight thereof is 100. . In each of the polymerizations of the present invention, the above range is obtained per 100 parts by weight of the monomer which constitutes the binder resin finally and which contains the acid group-containing monoethylenically polymerizable monomer as an essential component. It is better to prepare

In the first to third inventions, a water-soluble polymer compound is generally used as the dispersion stabilizer that can be used during suspension polymerization, and examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose and carboxymethyl cellulose. , Cellulose gum, rumzan gum and the like.

Further, it is insoluble in water and has a particle size of 0.01 to 5 μm.
Inorganic fine powder of m can also be used as a suspension dispersion stabilizer, for example, tricalcium phosphate, talc, bentonite, kaolin, titanium oxide, alumina, zinc white, aluminum hydroxide, magnesium hydroxide, basic magnesium silicate, Examples thereof include titanium hydroxide, ferric hydroxide, barium sulfate, silica, magnesium carbonate, calcium carbonate and the like.

These dispersion stabilizers may be used alone or in combination of two or more. The amount used is usually 0.1 to 10 parts by weight per 100 parts by weight of all reactive monomers.

In the fourth and fifth inventions, examples of the emulsifier that can be used in emulsion polymerization include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dodecyldiphenyloxide disulfonate, and polyanionic surfactants. Examples thereof include nonionic surfactants such as oxyethylene lauryl ether and polyoxyethylene ninyphenol ether. These may be used alone or in combination of two or more. The amount used is usually 0.01 to 5 parts by weight per 100 parts by weight of the total reactive monomers.

In the suspension polymerization, a part of the emulsifier may be used in combination with the dispersion stabilizer, and in the emulsion polymerization, a part of the dispersion stabilizer may be used in combination with the emulsifier. Further, a self-emulsifiable epoxy resin or a self-emulsifiable polyurethane resin can be used in place of the dispersion stabilizer or the emulsifier.

In the practice of the first to fifth inventions, if necessary, for example, dodecyl mercaptan, carbon tetrachloride,
A chain transfer agent such as thioglycolic acid, a reducing agent such as sodium acid sulfite, sodium thiosulfate and sodium metabisulfite, and a chelating agent such as sodium ethylenediaminetetraacetate may be used in combination therewith.

In the first invention, the acid group-containing monoethylenically polymerizable monomer, the colorant, the dispersion stabilizer and the liquid medium insoluble in the monomer, insoluble in the liquid medium and soluble in the monomer The polymerization initiator may be added at the same time, and the monomer droplets may be polymerized by stirring, but the acid group-containing monoethylenically polymerizable monomer and the colorant may be sufficiently prepared in advance with, for example, a ball mill or a colloid mill. And then add it to the liquid medium containing a polymerization initiator, a dispersion stabilizer, for example a homogenizer,
Stir with a rotor-stator mixer, static mixer, etc. to suspend the monomer droplets containing the acid group-containing monoethylenically polymerizable monomer in the liquid medium, and continue stirring to give the desired particle size. It is preferable to carry out the polymerization until the toner particles are formed. This suspension polymerization is suitable for obtaining micron-sized toner particles.

In the fourth aspect of the present invention, when toner particles having a submicron size are obtained, an acid group-containing monoethylenically polymerizable monomer, a colorant, an emulsifier and an aqueous medium, and a water-soluble polymerization initiator are added at the same time. The monomer droplets may be emulsified and dispersed in an aqueous medium and polymerized, but in the case of obtaining toner particles of micron size, an acid group-containing monoethylenic polymerizable monomer, an emulsifier, a water-soluble polymerization initiator And an aqueous medium are sufficiently mixed and emulsified and dispersed in advance and then polymerized to form primary particles, and then a coloring agent is added to the primary particles and stirred to allow the primary particles to be adsorbed and associated with the primary particles to contain a coloring agent. Secondary particles are formed, and the secondary particles are granulated by slowly aggregating the secondary particles so that the particles have a predetermined particle size, and the dispersion liquid is heated to a temperature equal to or higher than the glass transition temperature of the binder resin in the agglomerated particles. Fuse the interface between the secondary particles It is preferable to.

The suspension polymerization has a merit that impurities are finally less likely to be included as compared with the emulsion polymerization because the particles are relatively large from the beginning and the polymerization is carried out in one step.

In addition, ultrasonic waves may be added, if necessary, in uniformly mixing or dispersing each material. As in the case of the third invention, when the first invention is modified so that the colorant and the monoethylenically polymerizable monomer containing an acid group are mixed by ultrasonic wave to carry out the polymerization, a dispersion stabilizer is particularly used. Is not necessary.

The ultrasonic wave has a frequency of 16000, for example.
A sound wave of c / sec or more can be used. Ultrasonic waves, for example
High frequency voltage is applied to the crystal unit, and the fundamental frequency or odd multiple
Can be easily obtained by resonating at the frequency
You. 10^Fivesec^-1In the case of, a magnetostrictive oscillator is often used.
Can be The characteristic of ultrasonic waves is that the frequency is large and therefore the wavelength
It develops due to its shortness and its extremely high strength.
Frequency of 10 for liquid ⁶sec^-1Strength 10 watt
/ Cm²When, the acceleration of medium particles is
10^Five-10⁶And bring about the effects of emulsification and dispersion.

Since ultrasonic waves are used in the third invention, the dispersion stabilizer is substantially unnecessary. However, when the dispersion stability is further improved without using the dispersion stabilizer, the above-mentioned monomer may be used. It is also effective to use in combination a liquid medium having a relatively good affinity.

In the present invention, the liquid medium means water and / or an organic solvent which is in a liquid state at room temperature, while the aqueous medium contains water as a main component and optionally an organic solvent. It means a liquid medium that may be used. The aqueous medium is
It is preferable that the composition is such that only water or an organic solvent is contained in an amount of 30% by weight or less.

As the liquid medium which can be used for carrying out the polymerization in the present invention, various aromatic hydrocarbons such as distilled water, ion-exchanged water and the like, as well as various aromatic hydrocarbons such as toluene, xylene or benzene; methanol, ethanol,
Various alcohols such as propanol or butanol; Various ether alcohols such as cellosolve or carbitol; Various ketones such as acetone, methyl ethyl ketone or methyl isobutyl ketone; Various esters such as ethyl acetate or butyl acetate , Or butyl cellosolve acetate,
Examples include various ether esters.

In any polymerization method, the core-
By employing a shell polymerization formulation, a power feed polymerization formulation, or a graft polymerization formulation, the chemical structure and layer structure of the particles can be varied. The reaction conditions in each of the suspension polymerization method and the emulsion polymerization method of the above inventions are not particularly limited, and in each case, the reaction temperature is usually from room temperature to 80 ° C. for 15 minutes to 24 hours.

In obtaining the aqueous dispersion of toner particles used in the present invention, an auxiliary agent such as wax or a charge control agent may be added, if necessary, in any step of its production.

Examples of the auxiliaries include waxes such as polyethylene wax, polypropylene wax and paraffin wax, metal soaps, lubricants such as zinc stearate,
Alternatively, an abrasive such as cerium oxide or silicon carbide, a copper phthalocyanine, perylene, quinacridone, an azo pigment, an azo metal-containing dye, a charge control agent such as an azochrome complex, etc. may be mentioned.

Each first of the first invention, the third invention or the fourth invention
In the step, in the toner particle dispersion liquid containing the binder and the colorant, which are obtained as described above and are made of a polymer of an ethylenically polymerizable monomer containing an acid group, as a second step, Ammonia or an organic amine is added to neutralize the acid groups represented by the carboxyl group, phosphoric acid group and sulfonic acid group in the polymer, particularly the acid groups exposed on the surface of the toner particles. At this time, stirring is usually carried out to mix and disperse the ammonia or the organic amine so that the dispersion becomes uniform.

The organic amine used here may be a nitrogen-containing compound capable of forming an ion pair with a carboxyl group, a phosphoric acid group, a sulfonic acid group or the like, and specifically, for example, triethylamine, tri-n-butylamine, Triallylamine, tri-n-pentylamine, trihexylamine, tribenzylamine, triphenylamine, dimethyl-n-laurylamine, dimethyl-n-palmitylamine, dimethyl-n-stearylamine, dimethyl-
Tertiary amines such as benzylamine and dimethylaniline, diethylamine, di-n-butylamine, diallylamine, di-n-pentylamine, dihexylamine,
Secondary amines such as dibenzylamine and diphenylamine, primary amines such as t-butylamine, iso-butylamine, n-butylamine, 2-aminobenzotrifluoride, m-aminoacetophenone and 4-aminoacetanilide. Can be mentioned.

The amount of ammonia or organic amine used in the present invention is usually 0.3 with respect to the acid groups on the surface of the toner particles.
˜100 mol% equivalent can be used, but more preferably, addition of 3 to 85 mol% equivalent gives good results. Within this range, the sufficient effects of the present invention can be obtained, and the characteristics of the toner particles themselves are not impaired. Of course, it may be added as it is or as a solution.

The amount of acid groups on the surface of the toner particles can be determined by a titration method. For example, the concentration can be calculated by the following method. To the granulated aqueous dispersion of toner particles, an excess of 1N sodium hydroxide aqueous solution is added and thoroughly mixed with stirring to add sodium ions to the acid groups on the surface of the toner particles. Then, the aqueous dispersion of the toner particles is filtered and washed to remove excess sodium hydroxide other than those ionically bonded to the functional groups on the surface of the particles. Next, the toner particles are redispersed in water, and a 1N aqueous hydrochloric acid solution is added dropwise while stirring until the pH of the aqueous dispersion becomes 3. From the dropped amount of this 1N hydrochloric acid, the amount of sodium ions on the surface of the toner particles, that is, the amount of acid groups can be calculated. This method is suitable for measuring the carboxyl group content.

In the case of the above-mentioned second and fifth inventions, since the monoethylenically polymerizable monomer containing an acid group, which has been neutralized with ammonia or an organic amine in advance, is essentially used for the polymerization, The essential second step in the first, third, and fourth inventions is unnecessary. In addition, since the monoethylenically polymerizable monomer having a pre-neutralized acid group has excellent affinity to a liquid medium, an essential dispersion stabilizer or emulsifier is required at the time of polymerization of the first invention and the third invention. It may be used according to

The toner particle dispersion thus obtained typically contains toner particles having a structure in which the compound of the following general formula is ionically attached to the surface of the above-mentioned toner particles.

[0061]

Embedded image

A dry toner can be easily obtained by removing the liquid medium and drying the thus obtained toner particle dispersion liquid. In addition, it is preferable to repeatedly perform washing in order to remove the dispersion stabilizer and the emulsifier in the dispersion liquid. In carrying out the liquid medium removal / drying step, after filtering the toner particles, it is possible to perform hot air drying or freeze drying at a temperature at which the toner does not fuse, or to remove and dry the liquid medium with a spray dryer or the like. You may make it perform simultaneously.

According to the first to fifth aspects of the present invention, a spherical toner having a narrow particle size distribution (monodispersion) can be obtained, but if necessary, further classification may be performed.

As the particle size of the toner powder of the present invention, any size can be selected within a practical level as a toner. The volume average particle diameter is 3 to 30 μm, preferably 4 to 12 in view of the matching property with the current machine.
The range of μm is preferable.

The electrophotographic toner of the present invention can be used as a non-magnetic one-component toner or a magnetic one-component toner, or as a two-component developer when combined with a carrier, and is particularly excellent as a two-component developer. The characteristics can be obtained.

As the carrier, any known carrier can be used. Examples thereof include iron, nickel, copper, zinc,
Powders of metals such as cobalt, manganese, chromium, rare earths and alloys or oxides thereof, surface-treated glass, silica and the like can be used. Of course, resin-coated carriers such as acrylic resin-coated carriers, fluororesin-coated carriers, and silicone resin-coated carriers can also be used. As the carrier, for example, a carrier of about 20 to 200 microns is used.

When a two-component electrostatic image developer is obtained from the toner obtained in the present invention and a carrier, for example, the toner is mixed in an amount of 1 to 15 parts by weight of toner per 100 parts by weight of carrier. You can use it.

[0068]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a preferred embodiment of the present invention will be specifically described with reference to an example of producing a black toner by a suspension polymerization method.

First, with the styrene-based monomer as the main component,
(Meth) acrylic acid ester, (meth) acrylic acid,
The glass transition temperature of the polymer (binder resin) after polymerization is 50.
~ 80 ° C, content of (meth) acrylic acid in all monomers 1
It is used so as to be 0 to 20% by weight and the total monomer 1
2 to 8 parts by weight of carbon black powder per 100 parts by weight, 0.5 to 3 parts by weight of azo polymerization initiator per 100 parts by weight of all monomers, 0.05 to 3 parts by weight per 100 parts by weight of all monomers Partial amount of sulfur chain transfer agent,
0.3 to 3 parts by weight of a polyolefin wax is dispersed and mixed in advance under ultrasonic vibration per 100 parts by weight of all the monomers, and water is added to the mixture to suspend the monomer droplets while stirring. Polymerization is performed at ˜95 ° C. for 3 to 8 hours to obtain a dispersion liquid of toner particles in which carbon black particles are encapsulated and a polyolefin wax is finely dispersed and a particle size is 4 to 12 μm and a carboxyl group is exposed on the particle surface.

Next, the dispersion liquid was mixed with an organic third amount of 50 to 85 mol% of the exposed carboxyl groups of the toner particles.
A primary amine is added and uniformly mixed and dispersed to neutralize at least a part of the carboxyl groups, and then the toner particles are filtered off from the dispersion liquid to soften the binder resin forming the toner particles. Dry it below to obtain a toner powder.

The toner powder thus obtained is mixed in an amount of 3 to 10 parts by weight per 100 parts by weight of the carrier and can be used as a two-component developer for developing an electrostatic image.

[0072]

The present invention will be described more specifically below with reference to examples of the present invention. However, the invention is not limited to these examples.

(Example 1) Methacrylic acid 45 g Styrene 207 g Butyl acrylate 30 g Methyl methacrylate 15 g Ethylene glycol monomethacrylate 3 g Azobisisobutyronitrile 6 g Dodecyl mercaptan 3 g Elftex 8 15 g [Basic carbon black manufactured by Cabot Corporation of the United States] Viscor 550P 3g [Sanyo Chemical Co., Ltd. polypropylene wax]

After the above mixture was dispersed by an ultrasonic homogenizer, 1500 g of ion-exchanged water was added and dispersed and suspended. This mixed liquid was placed in a flask equipped with a stirring blade, and suspension polymerization was carried out at 80 ° C. for 5 hours under a nitrogen stream to prepare an aqueous dispersion of toner particles composed of resin fine particles containing a colorant. When the toner particles were measured with a Coulter counter, they were toner particles having an average particle diameter of 8 microns. Further, it was confirmed by observation with an electron microscope that the toner particles were truly spherical.

Next, with respect to this toner particle aqueous dispersion,
0.29 g of tri-n-butylamine was added and sufficiently stirred. Then, the toner particle dispersion liquid was filtered and treated with a freeze dryer for 3 days to obtain a dry toner. This toner had excellent fluidity, and no aggregation of particles was observed.

The obtained dry toner was treated with an average particle diameter of 80 μm.
The developer was adjusted by mixing and stirring 5 parts by weight with respect to 100 parts by weight of the ferrite carrier of m, and the environmental stability of the charging characteristics was confirmed. Under low temperature and low humidity conditions of 10 ° C. and 40% RH, -36.1 μC / g, and under high temperature and high humidity conditions of 35 ° C. and 80% RH, -37.0 μC / g, showing almost the same charge amount. . When a copy test was carried out using a commercially available electronic copying machine using this developer, even when the room temperature was changed to high temperature / high humidity / low temperature / low humidity, a uniform image density was obtained.
A clear image faithful to 0000 or more originals was obtained.

(Comparative Example 1) Tri-n- used in Example 1
A dry toner was prepared without adding butylamine. That is, a toner was prepared in which the organic amine was not ionically added to the carboxyl groups on the surface of the toner particles.

This toner was as excellent in fluidity as the toner obtained in Example 1, and no aggregation of particles was observed. However, when a developer was prepared by mixing and agitating 5 parts by weight with 100 parts by weight of a ferrite carrier having an average particle diameter of 80 μm and confirming environmental stability of charging characteristics, low temperature and low humidity of 10 ° C. and 40% RH were confirmed. Under conditions −
Under the conditions of high temperature and high humidity of 50.5 μC / g, 35 ° C. and 80% RH, the charge amount was −36.9 μC / g, and the fluctuation range was large. When a copy test was conducted with a commercially available electronic copying machine using this developer, when the room temperature was changed to high temperature / high humidity / low temperature / low humidity, the image density changed and a clear image faithful to the original was obtained. I couldn't.

[0079]

According to the invention of claim 1, toner particles comprising a binder resin containing a colorant and comprising an acid group-containing monoethylenically polymerizable monomer are obtained by suspension polymerization. Since at least a part of the acid groups exposed on the surface of the toner particles is neutralized with ammonia or an organic amine, a toner having excellent environmental stability is less likely to contain impurities than the emulsion polymerization method described later, and is easily obtained. A remarkable effect is obtained.

The present invention of claim 2 is a toner particle comprising a binder resin containing a colorant and comprising a monoethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine. Therefore, it is not necessary to use an essential dispersion stabilizer, and a toner having more excellent environmental stability can be easily obtained with less impurities than the emulsion polymerization method described below. A remarkable effect is obtained.

According to the third aspect of the present invention, the colorant and the monomer are mixed or dispersed by ultrasonic waves, and then the colorant is included and the monoethylenic polymerizable monomer containing an acid group is used. Since the toner particles composed of the binder resin are obtained by suspension polymerization, it is not necessary to specifically use the essential dispersion stabilizer in claim 1, and a toner having more excellent environmental stability can be obtained by using an impurity content higher than that of the emulsion polymerization method described later. It is extremely small and easily obtainable.

According to a fourth aspect of the invention, toner particles containing a colorant and comprising a binder resin composed of a monoethylenically polymerizable monomer containing an acid group are obtained by emulsion polymerization, and the toner is obtained. Since at least a part of the acid groups exposed on the surface of the particles is neutralized with ammonia or an organic amine, a particularly remarkable effect of obtaining a toner having excellent environmental stability can be obtained.

A fifth aspect of the present invention is a toner particle comprising a binder resin containing a colorant and comprising a monoethylenically polymerizable monomer having an acid group neutralized with ammonia or an organic amine. Since it is obtained by emulsion polymerization, a particularly remarkable effect that a toner having more excellent environmental stability can be obtained without using an emulsifier is obtained.

Since the invention of claim 6 uses a wax together during the polymerization, a particularly remarkable effect that a toner having a better releasability can be obtained can be obtained.

In the invention of claim 7, since basic carbon black is used, a particularly remarkable effect that a toner having excellent affinity for the binder resin and more stable charging characteristics can be obtained can be obtained.

Claims (7)

[Claims] 1. A colorant, a monoethylenically polymerizable monomer having an acid group, and a dispersion stabilizer as essential components in a liquid medium in which the monomer is insoluble and insoluble in the liquid medium and Polymerization is carried out in the presence of a monomer-soluble polymerization initiator to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer including a colorant. A second step in which ammonia or an organic amine is added to neutralize the acid groups in the polymer, then a third step in which the liquid medium is removed and dried.
A method for producing an electrophotographic toner, which comprises steps. 2. A liquid medium in which the monomer is insoluble, the liquid medium containing a colorant and a monoethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine as essential components. Polymerization is carried out in the presence of a polymerization initiator insoluble in and soluble in the monomer to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is composed of a polymer of the monomer containing a colorant.
A method for producing an electrophotographic toner, which comprises a step, and then a second step of removing the liquid medium and drying the same. 3. A colorant and a monoethylenically polymerizable monomer containing an acid group as essential components, which are ultrasonically mixed to each other in the liquid medium in which the monomer is insoluble. Polymerization in the presence of a polymerization initiator insoluble and soluble in the monomer to obtain a dispersion liquid of the toner particles insoluble in the liquid medium, which is a polymer of the monomer containing a colorant. A method for producing an electrophotographic toner, which comprises a second step of adding ammonia or an organic amine thereto to neutralize the acid groups in the polymer, and then a third step of removing the liquid medium and then drying. 4. A coloring agent, a monoethylenically polymerizable monomer having an acid group, and an emulsifier as essential components, which are polymerized in an aqueous medium in the presence of a water-soluble polymerization initiator to obtain a coloring agent. A first step of obtaining a dispersion of the toner particles insoluble in the aqueous medium, which comprises a polymer of the monomer, and a second step of adding ammonia or an organic amine thereto to neutralize the acid groups in the polymer A process for producing an electrophotographic toner, which comprises a step, and then a third step of removing the aqueous medium and drying. 5. A colorant and a monoethylenically polymerizable monomer containing an acid group neutralized with ammonia or an organic amine as essential components in the aqueous medium in the presence of a water-soluble polymerization initiator. The first step of obtaining a dispersion liquid of the toner particles insoluble in the aqueous medium, which is made of a polymer of the monomer including a colorant, and then the second step of removing the aqueous medium and drying. Method for producing photographic toner. 6. The method according to claim 1, 2, 3 or 4, wherein a wax is used together during the polymerization. 7. The method according to claim 1, 2, 3 or 4, wherein basic carbon black is used as the colorant.