JPH0990675A - Manufacture of electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner capable of comparatively freely controlling charge characteristics of a toner prepared by the phase-change emulsification process and easily adjusting a charging amount to a desired value and its manufacturing method and, in more detail, to enable control of charge amount to a desired value by easy operation in the wet chemical surface modification of the toner obtained by the same process and its manufacturing method. SOLUTION: The electrophotographic dry toner is obtained by granulating the toner prepared by the phase-change emulsification process and having an acid group added on the surface, dispersing the toner granules into an aqueous medium, mixing an aminocoupler into the dispersion liquid, removing the aqueous medium and drying the granules.

Description

Detailed Description of the Invention

[0001]

The present invention relates to electrophotography, electrostatic recording,
The present invention relates to a dry toner composition for developing an electrostatic latent image in electrostatic printing or 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. .

Normally, the polarity of the electrostatic latent image formed on the photosensitive member is positive or negative depending on the type of the photosensitive member and the difference in the developing system. Is also required to have a charging property with a negative or positive polarity opposite to the electrostatic latent image on the photoconductor.

In recent years, a wet-process toner has attracted attention as a toner whose amount used as an image forming material for a copying machine, a laser printer and the like is increasing.

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 and mechanically mixed with an external additive or the like, if necessary, and the shape of the particles is an angular polyhedral shape like crushed ice. I was trying.

On the other hand, in JP-A-5-66600, as a method for producing a wet-type toner, completely different from a conventional mechanical pulverization method, a binder resin in an aqueous medium in the presence of a colorant or the like is used. A wet process is described in which the colorant-encapsulated toner particles are obtained by phase inversion emulsification of the polymer to be obtained, whereby the toner particles are produced in one step.

A major feature of this wet process is that the toner shape can be made substantially spherical and that a uniform particle toner having a sharp particle size distribution can be easily produced. 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.

[0009]

However, the toner obtained based on such a phase inversion emulsification method has a problem that it is inferior in charging property to the conventional pulverization method toner and it is difficult to impart an appropriate triboelectric charging property. I was holding. In order to be a practical toner, it is necessary to develop an appropriate amount of charge suitable for a machine such as a copying machine or a printer.

If the amount of charge of the toner developed by frictional charging is too high or too low, it adversely affects the developing process and the transferring process, and a good final image cannot be obtained. Further, the toner is required to have a rapid charging rising speed. Since charges are applied to the toner particles by friction with the carrier or the sleeve, when the charge rising speed is insufficient, there arises a problem that the image density is lowered at the time of start-up or toner replenishment.

The stability of the charged toner over time is also an important charging characteristic. If the charge amount of the toner changes due to continued friction with the carrier or sleeve, it is not possible to obtain a large number of stable final images.
Furthermore, it is necessary to satisfy the above requirements even with environmental changes such as temperature and humidity, and it is required to have good environmental stability.

As described above, as a practical charging property of the toner, it is important to secure a balance of an appropriate amount of charge, a charging rising speed, stability over time, environmental stability, etc., but the conventional phase inversion emulsification method is used. With toner, there is a restriction that the toner particles are granulated under a wet condition, and it is difficult to perform charge control to obtain a toner having desired charging characteristics, and as a result, stable high-quality images cannot always be obtained. I had a problem.

In view of the above circumstances, the present invention provides a phase inversion emulsification method toner having good charging characteristics and a method for manufacturing the same, and more specifically, it easily controls the magnitude of the charge amount to an arbitrary value. Can be the charge rising speed,
An object of the present invention is to provide a wet-process electrophotographic toner having excellent properties with respect to stability over time and environmental stability, and a method for producing the same.

[0014]

As a result of intensive studies, the inventors of the present invention have solved the above problems. That is, the present invention, in order to solve the above problems, a toner particle surface containing an acidic group on the surface obtained by phase inversion emulsification of an organic solvent solution of a binder resin in which a colorant is dispersed, in an aqueous medium, Provided is an electrophotographic toner comprising an aminosilane coupling agent fixed by an ionic bond, and a method for producing the same.

Specifically, the organic solvent solution of a self-water-dispersible resin having an acidic group, at least a portion of which is neutralized with a basic compound, in which a colorant is dispersed, and an aqueous medium are added to carry out phase inversion. The first step in which the emulsified and neutralized acidic group forms an aqueous medium dispersion of toner particles exposed on the surface of the toner particles, the dispersion obtained in the above step is mixed with an acid, and the neutralized acidic The second step of returning the group to an unneutralized acidic group to obtain an aqueous medium dispersion of toner particles in which the acidic groups are exposed on the surface, and then mixing the dispersion obtained in the above step with an amino coupling compound, A third step of neutralizing the acidic groups in the dispersed toner particles with the amino coupling compound to fix the ionic bond to obtain an aqueous medium dispersion of the toner particles having the acidic groups neutralized with the amino coupling compound,
It is intended to provide a method for producing an electrophotographic toner, which comprises a fourth step of removing an aqueous medium from the aqueous dispersion of toner particles obtained in the above step and drying the same.

In the production method of the present invention, after the toner particles are formed, the acidic groups present therein are modified,
Only the surface of the toner particles can be selectively chemically modified, and in particular, the surface characteristics of the toner can be modified.

The toner particles usable in the present invention are particles containing a colorant and a synthetic resin as essential components, and the resin containing the colorant dispersed therein has an acidic group (eg, carboxyl group, phosphoric acid group, A toner particle having a predetermined average particle diameter, which contains a functional group having anion forming ability such as a sulfonic acid group) and has a part of the functional group exposed on the surface of the particle. The synthetic resin acts as a binder resin.

As the binder resin having such an acid group exposed on the surface, for example, a synthetic resin having an acid group in an unneutralized state in the molecule can be used, and the resin is used so that the acid group is exposed on the surface. To be Of course, it may have a functional group other than the acid group. Examples of such resin include epoxy resin, urethane resin, polyamide resin, acrylic resin, alkyd resin, polyester resin and the like. These may be used alone or in combination of two or more. Among them, an acrylic resin that is relatively easy to obtain a balance of powder fluidity, fixability, etc. as a toner,
A styrene / acrylate copolymer resin is especially preferable.

The above-mentioned resin has a molecular weight of a level required to exhibit sufficient mechanical strength, usually has a weight average molecular weight of 3,000 to 200,000, and, in the case of an acrylic resin, has 5,000 to 150,000, and D
In SC measurement, glass transition temperature (Tg) is 50 to 1
The temperature is preferably 00 ° C, and for heat roll fixing, the temperature is preferably about 60 to 80 ° C.

Taking an acrylic resin as an example of the resin, a polymer resin obtained by polymerizing a monomer such as (meth) acrylic acid ester can be mentioned as a typical example. Specifically, for example, styrene. , Α
-Styrenes such as methylstyrene, chlorostyrene, vinylstyrene, monoolefins such as ethylene, propylene, butylene, isobutylene, diolefins such as butadiene and isoprene, vinyl acetate, propion vinyl, vinyl butyrate, vinyl benzoate, etc. Α of vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, phenyl dodecyl acrylate, methyl methacrylate, ethyl methacrylate butyl methacrylate, dodecyl methacrylate, etc.
-Acrylic monomers such as vinyl ethers such as methylene aliphatic monocarboxylic acid esters, vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl propenyl ketone, acrylic acid and methacrylic acid Acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconic acid, monobutyl maleate,
Acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, 3-chloro-2
-Acrylamido-2-methylpropanesulfonic acid, 2
-The resin can be obtained by copolymerizing at least one kind of monomer selected from acid group-containing monomers such as sulfoethyl methacrylate.

Further, in detail of such an acrylic resin, a polymer unsaturated group-containing oligomer having an acid group can be used as a copolymerization component, such as maleic anhydride, fumaric acid, tetrahydrophthalic anhydride and endo. Vinyl-modified polyesters obtained by polycondensation or addition condensation of methylenetetrahydromaleic anhydride, α-terpinene maleic anhydride adduct and the like with monoallyl ether of triol, pentaerythrite diallyl ether or allyl glycidyl ether, dimethylolpropion Vinyl modified urethanes obtained by addition polymerization of diisocyanate with acid, glycerin monoallyl ether, 1,2 butadiene polyol, etc., vinyl modified by adding glycidyl group containing monomer to carboxyl group containing vinyl copolymer Epoxy, and the like can be mentioned.

As the polymerization initiator used to obtain such a resin, of course, an ordinary one can be used.
Various peroxides such as benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroxide or 2-ethylhexanoate; or azobisisobutyronitrile or azobisisovaleronitrile As mentioned above, various azo compounds and the like can be mentioned.

The resin itself may be obtained by solution polymerization in an organic solvent, suspension polymerization, emulsion polymerization, or bulk polymerization.

The polyester resin as the resin is
It can be obtained by condensation of a polyol and a polybasic acid, and an acid group can be easily introduced into an ordinary polyester resin by using an excessive amount of a dibasic acid such as phthalic acid.

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, calcyl 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 obtained toner 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 of these, 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.

The weight ratio of the colorant and the resin is not particularly limited, but it is preferable to set the colorant to 3 to 30% by weight when the total weight thereof is 100.

The toner particles made of the binder resin containing the colorant, which is obtained from the colorant and the binder resin, must have acid groups exposed on the surface of the particles. There are various methods for that purpose. In the conventional method of melt-kneading a colorant and a binder resin and pulverizing them to obtain toner particles, the acid group of the binder resin is the toner particles. It is unsuitable because it is randomly oriented inside and most of them are present inside the particles. Therefore, in order to selectively orient the acid groups on the surface of the toner particles with a high probability, a granulation method called phase inversion emulsification, which will be described in detail later, is suitable.

The method for obtaining an aqueous dispersion of toner particles having an acidic group on the surface of the particles in the present invention is not particularly limited, but if explained step by step, for example, the following method is used. Is mentioned.

First, a mixed composition, which is a solution of the resin in an organic solvent in which the colorant is dispersed, is prepared.

Examples of the organic solvent which can be used in preparing the organic solvent solution include various aromatic hydrocarbons such as toluene, xylene or benzene; various alcohols such as methanol, ethanol, propanol or butanol; cellosolve. Or various ether alcohols such as carbitol; various ketones such as acetone, methyl ethyl ketone or methyl isobutyl ketone; various esters such as ethyl acetate or butyl acetate; or various ether esters such as butyl cellosolve acetate And the like.

If the phase-inversion emulsification is carried out by using a hydrophobic organic solvent as a main component and a hydrophilic organic solvent compatible with it as a main component, toner particles having a more uniform particle size can be obtained.

At this time, the nonvolatile content of the organic solvent solution is not particularly limited, but usually 10 to 70% by weight is preferable.

Then, a mixed composition comprising an organic solvent solution of a synthetic resin having an acidic group, at least a part of which is neutralized with a basic compound, in which the colorant obtained above is dispersed is phase-inverted in an aqueous medium. A mixed composition comprising an organic solvent solution of a synthetic resin having an acidic group and having an acidic group dispersed therein by emulsification or capable of becoming self-water dispersible by neutralization, and at least making the resin self-water dispersible By inversion emulsification in a sufficient aqueous medium, the toner particles are granulated in the aqueous medium to prepare an aqueous dispersion of the toner particles. Of these methods, the former method is preferable.

Of course, in any of these methods, an aqueous medium may be added to the organic solvent solution for phase inversion emulsification, or the organic solvent solution may be added to the aqueous medium for phase inversion emulsification. You may go. The former is preferable because it is possible to obtain toner particles having a narrower particle size distribution, regardless of whether a resin that can be self-dispersible by neutralization is used or a self-dispersible resin is used. As a method of adding, dropping is generally used.

In order to smoothly carry out this phase inversion emulsion granulation, an emulsifier and / or a dispersion stabilizer may be contained in the organic solvent solution and / or the aqueous medium. In particular, when using a toner particle aqueous medium dispersion by phase inversion emulsification using a synthetic resin having relatively few acidic groups and poor self-dispersing performance as a binder resin, an emulsifier and / or a dispersion stabilizer are essential. Is.

As the dispersion stabilizer, a water-soluble polymer compound is generally used, and examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose and cellulose gum.

Examples of the emulsifier include sodium dodecylbenzene sulfonate, sodium lauryl sulfate,
Anionic surfactants such as sodium dodecyldiphenyl oxide disulfonate, and non-ionic surfactants such as polyoxyethylene lauryl ether and polyoxyethylene ninyphenol ether can be used in combination. Of course, the dispersion stabilizer and the emulsifier can be used together.

As described above, if a self-water-dispersible resin is used as the binder resin, phase inversion emulsification granulation can be performed without using a dispersion stabilizer or an emulsifier.

The self-water-dispersible resin is a synthetic resin containing in its molecule a functional group capable of becoming a hydrophilic group by neutralization, and some or all of the functional groups capable of becoming hydrophilic are neutralized by a neutralizing agent. In this case, the resin has the ability to form a stable aqueous dispersion without using an emulsifier or a dispersion stabilizer.

Examples of the functional group capable of becoming a hydrophilic group by neutralization in this resin include a so-called acidic group such as a carboxyl group, a phosphoric acid group and a sulfonic acid group. Taking a carboxy group-containing anionic resin as an example, The content of the carboxyl group of the resin, which can become an anionic hydrophilic group by neutralization, is not particularly limited,
An acid value of about 40 or more is preferable because particle formation by the phase inversion emulsification method is easy. Particularly preferably, the acid value is 50 to 1.
50.

The basic compound used to obtain the self-water-dispersible resin is limited to its type as long as the resin exhibits hydrophilicity such that it can be self-water-dispersed in an aqueous medium. Instead, compounds that readily generate cation ions in water can be used.

Specific examples of effective basic compounds include:
For example, sodium silicate, potassium silicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium phosphate dibasic, sodium phosphate tribasic, ammonium phosphate dibasic, ammonium phosphate tribasic, sodium metasilicate, carbonic acid. Inorganic metal basic compounds such as sodium and ammonia, mono, di or trimethylamine, mono, di or triethylamine, mono or diisopropylamine, n-butylamine, mono, di or triethanolamine, mono, di or tri Isopropanolamine,
Examples thereof include organic basic compounds such as ethyleneimine and ethylenediimine.

At that time, by carrying out phase inversion emulsification using the above-mentioned basic compound as a neutralizing agent, capsule fine particles can be produced in any case, but the particle size distribution of the produced particles is made sharp, that is, In order to obtain a toner having a uniform particle size, it is preferable to use an inorganic alkaline agent.

[0046] Such self-water dispersible resin was a binder resin phase inversion emulsification granulation, a colorant is dispersed, having an acid group, an organic solvent of the synthetic resin that can be the self-water-dispersible by neutralization After adding and dispersing the basic compound in the solution in an amount such that the former resin is self-dispersible, it is mixed with an aqueous medium for phase inversion emulsification, or a colorant is dispersed, having an acidic group, and neutralized. By mixing the synthetic resin organic solvent solution that can be self-water dispersible with the aqueous medium containing the basic resin in an amount that allows the former resin to be self-water dispersible and performing phase inversion emulsification, the colorant is included. Spherical particles of the above binder resin, which are dispersed in an aqueous medium containing an acidic group on the surface of the particles, can be used as an aqueous dispersion of toner particles.

The toner particles containing an acidic group on the surface of the particles obtained by the above-mentioned phase inversion emulsification granulation method exhibit good negative chargeability per se and can be used as a negatively chargeable toner.

The toner composition of the present invention can be obtained by ionic bond fixing of an amino coupling compound to the surface of toner particles having an acidic group on the surface of the particles.

A typical example of the amino coupling compound is an aminosilane coupling agent. At that time, the structure is not particularly limited, and a compound containing an amino group and an alkylsilane group in the molecule can be used, and in the commercially available product, N-β (aminoethyl) γ-aminopropyl is used. Methyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β
(Aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like can be preferably used.

In order to ionic bond and fix such an amino coupling compound to an acidic group such as a carboxyl group, a phosphoric acid group and a sulfonic acid group on the surface of toner particles, the above amino coupling is carried out in an aqueous dispersion of toner particles dispersed in an aqueous medium. This is easily achieved by adding the compound, mixing and dispersing, removing the aqueous medium, and drying to obtain a dry toner.

When phase inversion emulsification granulation using a basic compound is carried out, since the basic compound is ionically attached to a part of the carboxyl group, phosphoric acid group, sulfonic acid group and the like on the toner particle surface, If necessary, an acid may be added to the toner particle aqueous dispersion to carry out reverse neutralization treatment to remove the basic compound adhering to the particle surface. In addition, in the above treatment, for example, only toner particles are obtained by filtering and the like, and then a treatment of redispersing the toner particles in water is continuously performed to make an unneutralized acidic group and then an amino coupling compound is added. It is also possible to fix by ionic bond.

For the reverse neutralization treatment, known and commonly used acids can be used. For example, organic acids such as oxalic acid, acetic acid and propionic acid, and non-oxidizing inorganic acids such as formic acid, hydrochloric acid, sulfuric acid and phosphoric acid can be used. Can be mentioned. Among the above acids, it is preferable to use a non-oxidizing inorganic acid.

The addition amount of the amino coupling compound used in the present invention is 0.01 to the acidic groups on the surface of the toner particles.
An amount corresponding to 100 mol% can be used, and by changing the amount, it becomes possible to design a toner particle having a desired charge amount. As the amount of addition increases, the absolute value of the negative polarity charge decreases, and it is possible to convert the positive polarity charge toner.

The amount of acidic groups on the surface of the toner particles can be determined by, for example, a titration method. For example, the concentration can be calculated by the following method. To the toner particle aqueous dispersion containing granulated acidic groups,
Excess 1N sodium hydroxide aqueous solution is added, and the mixture is sufficiently stirred and mixed to add sodium ions to the acidic 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 dropping amount of this 1N hydrochloric acid, the amount of sodium ions on the surface of the toner particles, that is, the amount of acidic groups can be calculated.

Among the above-mentioned production methods exemplified for producing the toner particles having an acidic group on the surface, another step such as a water washing step for separately removing the dispersion stabilizer, the emulsifier and the like is unnecessary, and the production In terms of excellent properties, an aqueous dispersion obtained by a phase inversion emulsification method using a self-water-dispersible resin as a binder, which does not substantially use an emulsifier / dispersion stabilizer, is used as an aqueous dispersion of toner particles of the present invention. It is preferable to use

The phase inversion emulsification method using a self-water-dispersible resin without using an emulsifier or a dispersion stabilizer is compared with other toners of the phase inversion emulsification method, and the emulsifier or the dispersion stabilizer is added to the final toner powder. Therefore, a spherical dry toner having more stable charging characteristics can be obtained.

In obtaining the electrophotographic toner of the present invention, auxiliary agents such as waxes and charge control agents may be incorporated, if desired, 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, and the like.
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.

Dry type toner powder can be obtained by removing the aqueous medium from the aqueous dispersion of the toner particles in which the above-mentioned amino coupling compound is fixed by ionic bond and drying. In removing the aqueous medium from the dispersion, any effective method such as decantation or filtration can be adopted. In any of the methods of the present invention, when the toner particle aqueous medium dispersion contains an organic solvent, it is preferable to remove the organic solvent, then remove water and dry.

Any known and commonly used method can be adopted for the above-mentioned drying. For example, hot-air drying may be performed at a temperature at which toner particles are not thermally fused or aggregated, or freeze-drying may be used. There is also a method of simultaneously separating and drying toner particles from an aqueous medium using a spray dryer or the like.

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, and 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 at a ratio of 1 to 15 parts by weight of toner per 100 parts by weight of carrier. You can use it.

[0065]

BEST MODE FOR CARRYING OUT THE INVENTION Next, preferred embodiments of the present invention will be described. First, it has an acid value of 50, which has an acidic group and can become self-dispersible in water when at least a part thereof is neutralized.
~ 150, weight average molecular weight 5,000 to 150,000, T
Synthetic resin of g50-100 ° C., in an organic solvent solution mainly composed of a hydrophobic organic solvent, a hydrophilic organic solvent compatible with the hydrophobic organic solvent, and a total of 100% by weight of the resin solid content and the colorant. 3 to 30% by weight of the colorant are dispersed. Then, a metal basic compound sufficient to make the resin self-water dispersible is added to make the resin self-water dispersible.

In the organic solvent solution of the self-water-dispersible resin,
Aqueous medium is added and phase inversion emulsified, the neutralized acidic groups generate an aqueous medium dispersion of toner particles exposed on the surface of the toner particles, and the organic solvent contained in the dispersion is removed from the softening point of the toner particles. Is removed by distillation under reduced pressure so that the temperature is also low, the dispersion obtained in the above step and a non-oxidizing inorganic acid are mixed, and the neutralized acidic group is returned to the unneutralized acidic group,
An aqueous medium dispersion of toner particles having acidic groups exposed on the surface is obtained, the toner particles are filtered off, and then only the toner particles are redispersed in water.

Then, the dispersion liquid obtained in the above step is mixed with an aminosilane coupling agent, and neutralized with the coupling agent in an amount of 0.01 to 100 mol% of the acidic groups in the dispersed toner particles. Aqueous medium containing toner particles having a volume average particle diameter of 4 to 12 μm obtained by the above step, obtained by binding and fixing, and obtaining an aqueous medium dispersion of toner particles having an acidic group neutralized with the coupling agent. The aqueous medium is removed from the dispersion and dried.

Toner particle powders 1 to 1 thus obtained
By mixing 15 parts by weight with 100 parts by weight of the carrier, a two-component type electrostatic image developer can be obtained.

[0069]

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 1 200 g of methyl ethyl ketone
Was placed in a reactor and heated to 80 ° C. Then, the mixture in the proportions shown below was added dropwise over about 2 hours. Meanwhile, the reaction was carried out in a nitrogen stream.

Methacrylic acid 45 g Styrene 207 g 2-Ethylhexyl acrylate 33 g Methyl methacrylate 15 g Perbutyl O [manufactured by Nippon Shokubai Co., Ltd.] 3 g Methyl ethyl ketone 12 g

One hour after the completion of the dropping of the above mixture, 0.25 g of perbutyl O was additionally added, and then 0.25 g was added within 2 hours and the reaction was continued for 24 hours. After completion of the reaction, a styrene-acrylic copolymer resin solution having a nonvolatile content of 54% by weight and capable of becoming self-dispersible in water was obtained. This resin had an acid value of 100 and a weight average molecular weight of 40,000.

200 g of this copolymer solution, 35 g of isopropyl alcohol, and 12.0 g of "MA-100" (carbon black manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) were kneaded with "Eiger M-250VSE-EXJ" (manufactured by Eiger, USA). After mixing for 1 hour with a kneading machine), 11.5 g of a 1N-caustic soda aqueous solution was added, and water was added dropwise while stirring at 350 rpm using a three-one motor to perform phase inversion emulsification, and a colorant was included. An aqueous dispersion of toner particles comprising a self-water-dispersible resin was obtained. 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, the organic solvent was removed by vacuum distillation so that the temperature became lower than the softening point of the toner particles, and the pH was adjusted to 6
A 0.01N aqueous hydrochloric acid solution was added to the mixture until filtration and filtered and washed, and then the toner particles were returned to water to obtain an aqueous dispersion of toner particles. As an aminosilane coupling agent, N- (β-aminoethyl) was added to the aqueous dispersion of toner particles.
-Γ-aminopropyltrimethoxysilane (“SH6020” manufactured by Toray Dow Corning Silicone Co., Ltd.)
5 g was added, and sufficient stirring was performed in order to ion-fix the aminosilane coupling agent to 5.3% of the carboxyl groups on the surface.

Then, it 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 average particle size was also 8 microns, and no change in particle size due to treatment was observed.

The dry toner thus obtained has an average particle diameter of 100.
The developer was adjusted by mixing and stirring at a ratio of 4 parts by weight to 100 parts by weight of the micron coated ferrite carrier, and the charge amount of the toner was measured by the blow-off method. As a result, a value of +10.5 μC / g was shown, It was confirmed to be a charged toner. When a copying test was carried out using a commercially available electronic copying machine using this developer, a clear image faithful to 20,000 or more originals having a uniform image density was obtained. The dry toner thus obtained was mixed and stirred at a ratio of 3 parts by weight to 100 parts by weight of a non-coated ferrite carrier having an average particle size of 100 microns by changing the type of carrier, and a developer was prepared. When the charge amount was measured, it showed a value of −23.3 μC / g, and was confirmed to be a negatively charged toner. When a copying test was carried out using a commercially available electronic copying machine using this developer, a clear image faithful to 20,000 or more originals having a uniform image density was obtained.

(Examples 2 to 3) In the same manner as in Example 1, a toner was prepared in which an aminosilane coupling agent was ionic bond-bonded to the carboxyl groups on the particle surface. At that time, the amount of the aminosilane coupling agent added was 1.0 g (corresponding to 21.4% of the carboxyl groups on the surface) (Example 2), 2.0 g.
(Equivalent to 42.8%) (Example 3) and toner was adjusted. All the toners had an average particle size of 8 microns, and no change in particle size due to treatment was observed. A developer was prepared for the two types of carriers shown in Example 1,
The results of measuring the charge amount are shown in Table 1. It can be seen that the amount of the charge amount can be controlled by changing the amount of the aminosilane coupling agent fixed to the ionic bond, and the positive charge toner and the negative charge toner can be adjusted by selecting the type of carrier to be combined. The charge rising speed and stability over time when combined with a coating carrier are shown in FIG. It can be seen that the toner particles designed to have the respective charge amounts have good rising speed and good stability over time.

Comparative Example 1 A dry toner was prepared without adding the aminosilane coupling agent used in Example 1.
That is, a toner was prepared in which the aminosilane coupling agent was not ionically fixed to the carboxyl groups on the surface of the toner particles. Similar to the toner obtained in Example 1, this toner had excellent fluidity, and no aggregation of particles was observed. This dry toner was obtained by applying the average particle diameter of 1 shown in Example 1.
00 micron coated ferrite carrier 100
When a developer was prepared by mixing and stirring at a ratio of 4 parts by weight with respect to parts by weight, a charge amount of −30.5 μC / g was exhibited.
When a copying test was conducted using a commercially available electronic copying machine using this developer, the toner charge amount was too high, and only an image having a low density was obtained. Further, the type of carrier was changed, and the developer was prepared by mixing and stirring at a ratio of 3 parts by weight to 100 parts by weight of an uncoated ferrite carrier having an average particle diameter of 100 microns, and the charge amount of the toner was measured by a blow-off method. The value was −48.4 μC / g, and in this case as well, the charge amount of the toner was too high and only an image of low density was obtained.

[0079]

[Table 1]

[0080]

INDUSTRIAL APPLICABILITY The present invention is an electrophotographic image obtained by ionic bond fixing of an amino coupling compound to a negatively charged toner obtained by a phase inversion emulsion granulation method, that is, toner particles having an acidic group on the surface. It is a toner for use, and it is possible to easily adjust the toner of an appropriate charge amount suitable for the machine.
In addition, it is possible to obtain a toner having a charging property that is excellent in rising speed, temporal stability, and environmental stability at the set charge amount value. It is possible to easily control the charge of the wet process toner, and it is possible to easily manufacture the negatively chargeable toner and the positively chargeable toner.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the rising charging speed and the temporal stability of the toners obtained in Examples of the present invention and Comparative Examples.

Claims (10)

[Claims] 1. A phase-inversion emulsification by adding an organic solvent solution of a self-water-dispersible resin having an acidic group, at least a part of which is neutralized with a basic compound, in which a colorant is dispersed, and an aqueous medium.
The first step of forming an aqueous medium dispersion of toner particles in which the neutralized acidic groups are exposed on the surface of the toner particles, the dispersion obtained in the above step is mixed with an acid to remove the neutralized acidic groups. The second step of returning the neutralized acidic groups to obtain an aqueous medium dispersion of toner particles in which the acidic groups are exposed on the surface, and then the dispersion obtained in the above step and the amino coupling compound are mixed and dispersed in the toner. In the third step, the aqueous medium dispersion of toner particles having an acidic group neutralized with an amino coupling compound is obtained by neutralizing the acidic group in the particle with the amino coupling compound to fix the ionic bond. A method for producing an electrophotographic toner comprising a fourth step of removing an aqueous medium from the obtained aqueous dispersion of toner particles in an aqueous medium, followed by drying. 2. A solution of a colorant-dispersed resin having an acidic group and capable of becoming self-dispersing in water by neutralization with a basic compound, and at least sufficient self-dispersing water in the resin. The first step obtained by adding the aqueous medium containing a basic compound and subjecting it to phase inversion emulsification to form an aqueous medium dispersion liquid of toner particles in which neutralized acidic groups are exposed on the surface of the toner particles. The second step of mixing the dispersion liquid and an acid to return the neutralized acidic groups to the unneutralized acidic groups to obtain an aqueous medium dispersion of toner particles with the acidic groups exposed on the surface, and then in the above step The resulting dispersion is mixed with an amino coupling compound, the acidic groups in the dispersed toner particles are neutralized with the amino coupling compound to fix the ionic bond, and the acidic groups neutralized with the amino coupling compound are removed. Toner particles having The third step of obtaining an aqueous medium dispersion,
A method for producing an electrophotographic toner comprising a fourth step of removing an aqueous medium from the aqueous dispersion of toner particles obtained in the above step and drying the same. 3. The method according to claim 1, wherein the acid is a non-oxidizing inorganic acid. 4. The method according to claim 1, wherein the basic compound is an inorganic metal basic compound. 5. The method according to claim 1 or 2, wherein the organic solvent is removed from the aqueous dispersion of the toner particles, and the obtained dispersion is mixed with an acid. 6. An organic solvent is removed from an aqueous medium dispersion of toner particles obtained in the first step, the obtained dispersion is mixed with an acid, the second step is carried out, and then the second step is carried out. The production method according to claim 1 or 2, wherein the toner particles are separated from the dispersion liquid obtained in the step by filtration and redispersed in water to obtain an aqueous dispersion of toner particles, which is used in the third step. 7. The production method according to claim 1, wherein the amino coupling compound is an aminosilane coupling agent. 8. An organic solvent solution of a binder resin having an acidic group in which a colorant is dispersed, which contains an emulsifier and / or a dispersion stabilizer, and an aqueous medium are added to perform phase inversion emulsification. The first step of forming an aqueous medium dispersion of the toner particles exposed on the surface of the toner particles, and then the dispersion obtained in the above step is mixed with an amino coupling compound, and the acidic groups in the dispersed toner particles are mixed with the aminocapsule. Second step of obtaining an aqueous medium dispersion of toner particles having an acidic group neutralized with an amino coupling compound by neutralizing with a ring compound to fix the ionic bond, the aqueous dispersion of toner particles obtained in the above step A method for producing an electrophotographic toner, which comprises the third step of removing the aqueous medium and drying. 9. A toner containing a binder resin having an acidic group, in which a colorant is dispersed, in an organic solvent, and an aqueous medium containing an emulsifier and / or a dispersion stabilizer are added to perform phase inversion emulsification. First step of forming an aqueous medium dispersion of toner particles exposed on the surface of the particles, and then mixing the dispersion obtained in the above step with an amino coupling compound to convert the acidic groups in the dispersed toner particles to the aminosilane coupling Second step of obtaining an aqueous medium dispersion of toner particles having an acidic group neutralized with an amino coupling compound by neutralizing with an agent to fix ionic bonds, from the aqueous dispersion of toner particles obtained in the above step A method for producing an electrophotographic toner comprising a third step of removing an aqueous medium and drying. 10. The method according to claim 8 or 9, wherein the second step is carried out after removing the organic solvent contained therein from the aqueous dispersion of the toner particles in the aqueous medium obtained in the first step.