JPH1010778A - Production of toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a toner having a sharp distribution of the quantity of electric charges and a high rate of electrostatic charge. SOLUTION: A mixture contg. a self-water-dispersible resin (A) obtd. by neutralizing a resin (A') which can be made self-waterdispersible by neutralization with a neutralizing agent, an org. solvent dissolving the resin A and a colorant as essential components is subjected to phase inversion emulsification in an aq. medium to form particles of the self-water-dispersible resin contg. the colorant in a capsulated state and these particles are separated and dried to produce the objective capsule type toner. The colorant is a mixture of a colorant having polarity reverse to that of the resin A' with a colorant having the same polarity as the resin A'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a new and useful toner. More specifically, the present invention relates to a method for producing a toner containing a self-water-dispersible resin and a colorant, particularly for use in developing an electrostatic latent image.

[0002]

2. Description of the Related Art As a method for producing a toner for developing an electrostatic charge image,
As a dry method, there is a pulverization method in which a binder resin and a colorant are kneaded and pulverized and classified, and as a wet method, there is a polymerization method in which a colorant or the like is included at the time of polymerization to obtain a toner. A new method is disclosed in
There is a so-called phase inversion emulsification method described in Japanese Patent Publication No. 00 and the like. This is a method of dissolving and dispersing a self-water dispersible resin and a colorant in an organic solvent, and adding a suitable amount of water while stirring to cause phase inversion emulsification to generate fine particles and dry to obtain a dry toner. It is.

One of the characteristics required for a toner is a charging characteristic. In the electrostatic charge developing method, the toner is required to have an appropriate charge amount and to have a sharp charge amount distribution between particles. A toner having a low charge amount causes scattering and fogging. On the other hand, a toner having an excessively high charge amount makes the coated state of the toner on the sleeve unstable, so that the image density becomes non-uniform. The developing system has an appropriate charge amount, and if the charge amount deviates from the appropriate amount, the image density decreases.

Further, the charging speed is also an important factor. In other words, how long it takes for the toner added to the developer to compensate for the toner consumed in the copying machine to reach an appropriate charge amount by stirring in the developing machine becomes a problem. When the charging speed is low, a toner having a low charge amount is generated, and a high charging speed is required.

In the conventional pulverized monochrome toner, carbon black as a colorant is exposed on the particle surface due to the manufacturing method, and the exposed carbon black has conductivity. It is known that when the resistance is reduced and an excessive charge leaks, the amount of charge among the particles becomes uniform during frictional charging, that is, there is an effect of sharpening the charge distribution.

[0006] On the other hand, the production method disclosed in the above-mentioned publication, particularly in terms of charging characteristics, is that a conductive substance such as a coloring agent is embedded in a resin and is not exposed on the surface of the particle, and is a spherical particle. It has features not found in conventional manufacturing methods such as a pulverizing method.

[0007]

However, in the case of preparing an achromatic toner, for example, since the colorant carbon black is encapsulated and hardly present on the surface of the particles, the rise of the charge is insufficient. A sharp charge distribution was not obtained, and non-polar toner and reverse-polarity toner were easily generated, which caused troubles such as a decrease in triboelectric chargeability at the time of copying a large number of sheets, a background fog and a decrease in image quality.

The present invention uses a colorant having a different polarity to fix the colorant near the particle surface, thereby providing a sharp charge amount distribution required for high-quality copying and a high charge rate. An object of the present invention is to provide a method for producing an encapsulation toner.

[0009]

The inventors of the present invention have conducted intensive studies with the aim of solving the problems to be solved by the invention as described above. As a result, the base resin for obtaining a self-water-dispersible resin was obtained. And a colorant (C2) having the opposite polarity as the colorant (C2)
It has been found that toner particles having better chargeability can be obtained by using I), and the present invention has been completed.

That is, the present invention relates to a self-water-dispersible resin (A) obtained by neutralizing a resin (A ′) which can become self-water-dispersible by neutralization with a neutralizing agent, and the resin (A). A mixture (I) containing a dissolving organic solvent (B) and a colorant (C) as essential components is phase-inverted and emulsified in an aqueous medium to disperse self-water in which the colorant (C) is encapsulated. After the particles of the conductive resin are generated, the particles are separated and dried. In a method for producing a capsule-type toner, a colorant (C1) having a polarity opposite to that of the resin (A ′) is used as the colorant (C). The present invention provides a process for producing a capsule type toner, characterized by using a mixture (II) of a coloring agent (C2) having the same polarity as that of the above-mentioned (2).

The production method of the present invention is characterized by using a mixture (II) having a different polarity as the colorant (C).

For the toner particles of the present invention, known and commonly used colorants can be used. Specific examples include carbon black, magnetic powder, nigrosine dye, aniline blue, calcoyl blue, chrome yellow, and 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 1
5, iron sesquioxide, iron sesquioxide, iron powder, zinc oxide, selenium, etc., which can be used alone or in combination of two or more.

However, at this time, if the colorant (C) has the same polarity as the resin (A ′) which is a precursor of the resin (A) and can be self-dispersed in water by neutralization, the adsorptive power of both is sufficient. This is probably because under the action of water in the phase inversion emulsification step, the colorant (C) dispersed in the organic phase undergoes aggregation, and the colorant (C) is not uniformly taken into the particles. In some cases, the content of the colorant (C) differs, or a large aggregated piece existing near the particle surface is generated, which directly affects the dispersion state of the colorant (C) in the toner particles. . This deterioration of the dispersion state causes low charging due to an increase in the conductivity of the individual particles and deterioration in image quality due to deterioration in the distribution of the charge amount.

On the other hand, when a colorant having a polarity opposite to that of the self-water-dispersible resin (A) to be used or the resin (A ') which can be converted into a self-water-dispersible resin by neutralization is used, aggregation of the colorant (C) occurs. Although the charging property can be prevented from being reduced, since the colorant is encapsulated and hardly present on the particle surface, the charging rise is poor and a sharp charging distribution cannot be obtained, which causes a problem such as image deterioration when copying a large number of sheets. .

However, by using a mixture (II) of a colorant (C1) having a polarity opposite to that of the resin (A ') and a colorant (C2) having the same polarity as the resin (A'),
It became possible to partially fix the colorant near the particle surface, and it was possible to obtain a toner having a sharp charge amount distribution necessary for high-quality copying and having a high charging speed. The above-mentioned improvement effect is particularly remarkable when a conductive colorant is used as the mixture (II), for example, when carbon black is used.

Among the coloring agents (C) that can be used in the present invention,
The basic colorant has a pH> 7, preferably 8 or more, while the acidic colorant has a pH <7, preferably 6
The following are used: As such, those described above can be used, but those which have undergone a surface treatment depending on the colorant and have changed surface polarity are commercially available,
It is convenient to check the pH before use and use them. It is preferable to increase the difference in pH between the resin (A ′) and the colorant (C). Specifically, it is preferable that this difference be 4 to 8.

The particle size of the colorant (C) can be appropriately selected, but generally, the average primary particle size is 10 to 100.
nm.

The weight ratio of the colorants (C1) and (C2) constituting the mixture (II) is not particularly limited, but is usually (C1) / (C2) = 95/5 to 5/95, preferably 15/85 to 45/55.

Next, the self-water-dispersible resin (A) used in the present invention and the resin (A ') which can be converted into a self-water-dispersible resin by neutralization will be described.

The resin (A ') which can become a self-water dispersible resin upon neutralization used in the present invention is, for example, a resin having an anionic (acidic) or cationic (basic) hydrophilic group in the molecular chain. The hydrophilic group is neutralized with a base if anionic and with an acid if cationic, so that the hydrophilic group takes a salt structure and the hydrophilicity is enhanced. A resin that can be expressed, that is, a resin that becomes a self-water-dispersible resin (A).

The degree of hydrophilicity of the group which has been enhanced by the neutralization must be such that the resin (A) itself can be dispersed in water. By mixing the self-water-dispersible resin (A) thus obtained with an aqueous medium, phase inversion emulsification occurs without using an emulsifier, a dispersion stabilizer, or the like, and particles can be generated.

The self-water-dispersible resin (A) referred to in the present invention is a resin having an anionic (acidic) or cationic (basic) hydrophilic group in the molecular chain, and a base if anionic. If the cationic group is neutralized with an acid, the hydrophilic group has a salt structure and the hydrophilicity of the resin is increased, or a hydrophilic group having a salt concept in advance,
By mixing with an aqueous medium by these actions, phase inversion emulsification occurs without using an emulsifier or a dispersion stabilizer, and refers to a resin that forms particles.

In an aqueous medium, for example, a self-water-dispersible acrylic resin forms a hydrophilic particle on the particle surface (O / W interface) and takes a form that wraps around a hydrophobic part to form stable particles. It is.

As described above, the effect of the hydrophilic group is the same whether it is obtained by neutralizing a functional group in the resin with a neutralizing agent or when it is present in the resin as a previously neutralized salt structure. It is.

The self-water-dispersible resin (A) is obtained by neutralizing an acid group or a base group in the resin (A ′) (resin containing an acid group or a base group) which can be made self-water dispersible by neutralization.
In the case of the acid group-containing resin (A '), for example, a tertiary amine such as triethylamine, an inorganic base such as sodium hydroxide and potassium hydroxide, and ammonia are exemplified. On the other hand, in the case of the resin (A ') containing a basic group, for example, oxalic acid, acetic acid, hydrochloric acid and the like can be mentioned, and an appropriate amount of these is neutralized.

The hydrophilicity of the resin (A ') containing an acid group or a base group and capable of becoming self-water dispersible by neutralization is determined by the amount of the functional group or the amount of neutralization which can increase the hydrophilicity by neutralization. Neutralization ratio). Furthermore, the size of the particles at the time of dispersion in the second step described later is determined by the hydrophilicity. That is, it is possible to easily obtain particles having an arbitrary particle size by controlling the neutralization ratio.

The amount of the hydrophilic group (acid group or base group) which can be neutralized by the neutralizing agent in the resin (A ′) is not particularly limited, but the resin solid content is 100%.
The equivalent amount is 10 to 500 mg equivalent to g, preferably 10 to 400 mg equivalent to 100 g of resin solids.

Further, the amount of the neutralized hydrophilic group such as an acid group or a base (neutralization amount, neutralization ratio) required for the resin (A ′) to exhibit self-water dispersibility is determined by the composition of the resin. The hydrophilicity of the resin itself differs depending on the molecular weight, the structure, etc., and is different from each other, but usually within the range of 4 to 300 mg equivalent to 100 g of resin solid content, preferably 4 to 200 mg equivalent to 100 g of resin solid content. It is.

As the resin (A) or (A ′),
Considering the fixing property and the heat-resistant storage stability, which are one of the toner properties, for example, those having a glass transition temperature of 30 to 100 ° C., preferably 50 to 80 ° C., and a weight average molecular weight of 5,000 to 300,000 It is preferable to use

Examples of the resin (A ') and the self-water-dispersible resin (A) which can be made self-water dispersible by neutralization include acrylic resin, polyester resin, polyurethane resin, epoxy resin, alkyd resin and the like. . Acrylic resins, in particular, styrene / acrylate copolymer resins, in which the balance between powder fluidity and fixability as a toner can be relatively easily obtained, are particularly preferred. Next, an acrylic resin will be described as an example.

In the present invention, the acrylic resin which can become self-water dispersible by neutralization is defined as an emulsifier under the action of an aqueous medium by the action of a functional group in the molecule which can increase hydrophilicity by neutralization. And an acrylic resin having the ability to form a stable aqueous dispersion without substantially using a dispersion stabilizer.

Examples of the acrylic resin capable of becoming self-water dispersible by the neutralization include an acrylic polymerizable monomer containing an acid group or a basic group and a polymerizable monomer containing the hydrophilic group. Those obtained by subjecting a polymerizable monomer other than the above to radical polymerization in the presence of a radical initiator can be used. The polymerization reaction to obtain it, even in solution polymerization,
Suspension and emulsion polymerization can be used as appropriate.

Examples of such acid group-containing acrylic polymerizable monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconate, and monobutyl maleate.
Examples of the basic group-containing acrylic polymerizable monomers include acrylate derivatives such as dimethylaminoethyl, diethylaminoethyl, dibutylaminoethyl, and N-ethyl-N-phenylaminoethyl, and methacrylate derivatives.

Examples of the polymerizable monomers other than the acid group monomers include styrene monomers (aromatic vinyl monomers) such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene or chlorostyrene. There is styrene.

Examples of the acrylates include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, acryl 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate or dodecyl acrylate, 2-chloroethyl acrylate,
Examples include phenyl acrylate and methyl alpha-chloroacrylate.

Examples of the methacrylate include methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-methacrylic acid. Octyl, decyl methacrylate, dodecyl methacrylate, 2-chloroethyl methacrylate, phenyl methacrylate, and alpha-methyl methacrylate.

Also, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone. Examples thereof include vinyl ketones, N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinyl compounds such as N-vinylpyrrolidone, and the like.

For obtaining a resin (A ′) or a self-water-dispersible resin (A) which can be made self-water-dispersible by neutralization, a general-purpose solvent can be used in the case of solution polymerization. Specifically, for example, various aromatic hydrocarbons such as toluene, xylene or benzene; various alcohols such as methanol, ethanol, propanol or butanol; various alcohols such as cellosolve or carbitol;
Various ether alcohols; 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. Active solvent.

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

In the present invention, a self-water-dispersible resin obtained by neutralizing a resin which can become self-water-dispersible by neutralization is used as an essential component, and if necessary, a polyalkylene group containing a polyoxyethylene repeating unit is added. A small amount of a resin having self-water dispersibility without neutralization as in the case of an acrylic resin may be used.

Other reactions include a chain transfer agent such as dodecyl mercaptan, carbon tetrachloride, and thioglycolic acid; a reducing agent such as sodium acid sulfite, sodium thiosulfate and sodium metabisulfite; and a sodium transfer agent such as sodium ethylenediaminetetraacetate. A chelating agent may be used in combination.

The reaction conditions are not particularly limited, but are usually 0.
Above 140C at 140C for 15 minutes to 72 hours.

The resin which can become self-water dispersible by neutralization or the self-water dispersible resin used may be a single resin or a mixture of a plurality of resins having different molecular weights and different monomer compositions.

Although the anionic acrylic resin system has been described above, the quantitative relationship of the hydrophilic segment in the cationic resin is the same as that in the anionic acrylic resin. In the resin system, a polyester resin, a urethane resin, an epoxy resin, or the like can be used instead of the acrylic resin.

A self-water-dispersible polyester resin, that is, a polyester resin which can be converted into a self-water-dispersible resin by neutralization, can be synthesized and used by a known and commonly used method. For example, a polyester resin which can be a self-water dispersible resin having a carboxyl group as a hydrophilic group is synthesized by a usual polycondensation reaction.

That is, the raw material polybasic acid and polyhydric alcohol are dehydrated and condensed in the presence or absence of a solvent in the presence or absence of a solvent. Part of the polybasic acid may be subjected to demethanol polycondensation using the methyl esterified product.

Examples of the polybasic acid used include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid, maleic anhydride, fumaric acid, and succinic acid. And carboxylic acids such as alkenyl succinic anhydride and adipic acid.

The polyhydric alcohols used include:
For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and glycerin; alicyclic polyhydric alcohols such as cyclohexanediol, cyclohexanedimethanol and hydrogenated bisphenol A; bisphenol A And aromatic diols such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A.

A polybasic acid which is a raw material for polyester;
For example, the content of the terminal carboxyl group can be controlled by the mixing ratio and the reaction rate of the polyhydric alcohol. Alternatively, a carboxyl group can be easily introduced into the main chain by using trimellitic anhydride.

The polycondensation reaction is terminated when the acid value and the softening point have reached predetermined values, and the desired polyester resin which can become self-water dispersible can be obtained.

When the resin (A ′) is a urethane-based resin, a diol containing an acid group or a base group such as dimethylolpropionic acid or N-methyldiethanolamine can be used as a polyether polyol such as polyethylene glycol or a polyester. As a part of various polyol components such as polyols, acrylic polyols, polybutadiene polyols, and the like, the acid group is formed by a known method such as addition polymerization with a polyisocyanate such as tolylene diisocyanate, hexamethylene diisocyanate, or isophorone diisocyanate. Or a base group-containing urethane resin.

When the resin (A ′) is an epoxy resin, for example, a polyepoxycarboxylic acid such as adipic acid or trimellitic anhydride is added or polymerized to the base epoxy resin, or dibutylamine, ethylenediamine or the like is used. By the addition or addition polymerization of the above, an epoxy resin containing an acid group or a base group is obtained.

In the present invention, an organic solvent (B) that dissolves the self-water dispersible resin (A) is used. As the solvent (B), any of known and commonly used solvents can be used. Solvent (B)
One type may be used alone, or two or more different types may be used in combination. Organic solvent (B)
It is preferable to select a resin that dissolves not only the resin (A) but also the resin (A ′). For example, in the case of an acrylic resin based on solution polymerization as described above, an organic solvent used as a reaction solvent can be used.
In this case, the reaction solvent may be used as it is.
However, it is preferable to use a so-called low-boiling solvent that can be easily removed in the third step described later, such as methyl ethyl ketone or ethyl acetate. Also, for example, acetone, butanol, isopropyl alcohol, hexanediol, tetrahydrofuran,
Water-soluble such as dimethylformamide and butyl cellosolve,
Alternatively, a highly hydrophilic organic solvent having a surface tension reducing property can be used.

Other components (additive components) that can be used in the present invention include various auxiliaries such as charge control agents and release agents. Accordingly, they can be appropriately selected and used.

Next, the manufacturing process of the present invention will be described sequentially.
The present invention includes the following steps. First step: a self-water-dispersible resin (A) obtained by neutralizing a resin (A ′) that can become self-water-dispersible by neutralization with a neutralizing agent, and an organic solvent (B) that dissolves the resin. To obtain a mixture (I) in which the colorant (C) and, if necessary, other additives are uniformly mixed.

Second step: The mixture (I) obtained in the first step is phase-inverted and emulsified in an aqueous medium to produce particles. Here, the aqueous medium means a liquid medium containing only water or water as an essential component.

Third step: The particles are separated from the aqueous medium in which the particles are dispersed. In this case, the particles may be separated as they are, but usually, the solvent (B) is removed from the aqueous medium containing the organic solvent (B), and a neutralizing agent having a polarity opposite to that of the neutralizing agent is used. The processing is performed using. Here, the neutralizing agent includes only the neutralizing agent or an aqueous solution of the neutralizing agent.

Fourth step: Next, the particles are separated from the aqueous medium by filtration or the like, and dried to obtain a toner powder.

Next, each step will be described in detail. The first step will be described. In the first step of the present invention, first, the self-water dispersible resin (A) and the organic solvent (B)
A mixture (I) is prepared, which comprises the components (A) and (C) as essential components.

The mixture (I) comprises, for example, a self-water dispersible resin having an acid group neutralized with a base, a colorant (C)
It is a mixture containing [mixture (II)] and an organic solvent that dissolves the resin as essential components.

Such a mixture (I) may be prepared in any mixing order. For example, a resin which can be made self-water dispersible by neutralization having an acid group and a basic colorant are mixed in advance. Then, a base is added and neutralized to obtain a mixture containing a self-water dispersible resin, a basic colorant, and an organic solvent that dissolves the resin as essential components.

The resin which can become self-water dispersible by neutralization is neutralized in a necessary amount with the above-mentioned neutralizing agent before adding the aqueous medium.

The mixing of the coloring agent (C) is sufficiently dispersed by a known and commonly used means such as a disperser, for example, an agitator mill, a sand mill, and a ball mill. Since the present dispersion method is a wet method, a predetermined colorant (C) can be easily dispersed compared to melt kneading.

In preparing the mixture (I) containing the solvent (B), the solvent (B) is prepared by combining the resin (A) or the resin (A ') and the solvent (B) in advance and using a disperser or the like. Resin (A) even when dispersed together with colorant (C)
Alternatively, the same effect can be obtained by adding the resin (A '), the solvent (B) and the colorant (C) after dispersing them with a disperser or the like.

Of course, in the practice of the present invention, when a part or all of the acid group-containing resin forming toner particles is converted into a self-water dispersible resin, a functional group capable of increasing hydrophilicity by neutralization is used. A part or all of the group may be neutralized with a neutralizing agent having the opposite polarity.

On the other hand, when it is necessary to convert part or all of the self-water-dispersible resin into an acid group-containing resin as described later, a part or all of the hydrophilic groups contained in the self-water-dispersible resin are required. The whole may be neutralized with a neutralizing agent having the same polarity as the functional group which can potentially increase the hydrophilicity due to the neutralization.

Next, the second step will be described. This second
Through the process, particles composed of the self-water-dispersible resin (A) in which the colorant (C) is encapsulated are generated in the aqueous medium.

The organic continuous phase (O phase, mixture (I)) in which the self-dispersible resin is dissolved in an organic solvent is added to an aqueous medium (W).
Phase), emulsifier, dispersion stabilizer,
Without using so-called emulsifying aids such as suspension stabilizers, conversion of the resin from W / O type to O / W type (so-called phase inversion emulsification) is performed to form a discontinuous phase, The resin is dispersed and stabilized in the form of particles in an aqueous medium. As the water used in the present invention, it is preferable to use ion exchange water or pure water.

In this case, a method of phase-inversion emulsification by adding an aqueous medium to the above-mentioned mixture (I) under stirring, or conversely, adding the mixture (I) to an aqueous medium under stirring Although any method such as a method of forming toner particles by phase inversion emulsification may be used, the former method is preferable because the toner particle diameter distribution can be narrowed.

In the phase inversion emulsification, the aqueous medium may contain a neutralizing agent if necessary. Also in these methods, when phase inversion emulsification is not easily performed, a stronger mechanical shear force can be applied to forcibly form toner particles.

The self-water dispersible resin (A) used in the present invention
Is itself dispersed in water, but if necessary, a surfactant (emulsifier) such as the emulsifying aid and a dispersion stabilizer may be used in combination. However, their use is preferably kept to a minimum and very small. Examples of the emulsifier include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and sodium dodecyldiphenyloxide disulfonate; and nonionic surfactants such as polyoxyethylene lauryl ether and polyoxyethyleneninylphenol ether. No. As the dispersion stabilizer, a water-soluble polymer compound is used, and examples thereof include polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, and cellulose gum.

As a method equivalent to the above-mentioned second step, for example, the following method can be mentioned. Resin (A ′) that can be made self-water dispersible by neutralization, organic solvent (B) that dissolves resin (A ′), resin (A ′) and colorant (C) [mixture (II)] (E) phase-emulsifying a mixture (I) having the following as an essential component in an aqueous medium containing a sufficient amount of a neutralizing agent to make the resin (A ′) self-dispersible in water.

The third step is a step of performing processing as necessary before drying and pulverizing the toner particles formed in the previous step. The processing includes the following operations. 1. Desolvation: removing the organic solvent from the toner particles and the aqueous medium. As a result of the phase inversion emulsification in the second step, the organic solvent contained in the obtained toner particles and the aqueous medium can be removed by an operation such as distillation. By removing the organic solvent contained in the toner particles, swelling of the resin in the toner particles due to the organic solvent is eliminated, and the particles are solidified.

2. Primary washing: As a result of the phase inversion emulsification in the second step, the aqueous medium dispersion liquid containing the toner particles obtained contains the water-soluble components contained in the self-water dispersible resin and the submicron generated during emulsification. Contains a small amount of fine particles of the order. These water-soluble components and fine particles contain a conductive substance such as a coloring agent, and by performing this primary washing operation, these components are removed, and the particles are prevented from being adsorbed on the surface of the toner particles. .

Usually, by removing these components which are ionic substances, it is possible to obtain a more stable charging property such as a reduction in variation of the charging amount due to lot blur and a reduction in variation of the charging amount due to the environment. Next, the toner particles are separated from the aqueous medium by a method such as filtration, and the particles are washed with water.

3. Neutralization treatment: When the self-water-dispersible resin (A) constituting the toner particles obtained in the second step has a neutralized acid group, use of an acid or a neutralized base group In the case of having, processing is performed using a base. That is, a neutralizing agent having a polarity opposite to that of the neutralizing agent used to neutralize the resin (A ′) is used. For example, taking an anionic self-water dispersible resin as an example, the acid aqueous solution may be any strong acid, and usually a 0.1 to 1N hydrochloric acid aqueous solution can be used.

Here, by converting the resin, the resin can be used as a binder resin for toner having improved environmental resistance such as a change in humidity.

By such a treatment, the hydrophilicity of the resin (A) in the toner particles is reduced, and the toner particles composed of the resin (A ′) can be obtained. By performing this operation, the hydrophilicity of the particles is reduced, so that the separation from water is increased, and the subsequent processing can be performed smoothly. Such a neutralization treatment is performed by means such as immersing or contacting the toner particles in an aqueous acid solution or aqueous base solution. In addition, since such a treatment is a neutralization reaction, the generated salt is generally removed by washing.

In the fourth step, the toner particles are separated from the liquid medium, dried and powdered. The powdering method may be any method, and a commonly used powdering method may be used. Examples thereof include a freeze drying method and a flash drying method.

The powder toner comprising the aggregate of toner particles obtained according to the present invention is then subjected to a physical or chemical surface treatment on the surface of the toner particles by adding silica powder or the like to obtain various powders. It is also possible to carry out a modification. Needless to say, a charge control agent or a wax may be added as an additive in any step of toner production.

[0081]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments. 1. Resin (A ') that can become self-water dispersible by neutralization
-Water-dispersible resin (A) obtained by neutralizing water with a neutralizing agent
And a mixture (I) containing, as essential components, an organic solvent (B) dissolving the resin (A) and a colorant (C) in a phase inversion emulsification in an aqueous medium to give the colorant (C) After producing the encapsulated self-dispersible resin particles, the particles are separated and dried. In a method for producing a capsule-type toner, the reverse of the resin (A ′) is performed as a colorant (C). A mixture of a colorant (C1) having the following polarity and a colorant (C2) having the same polarity (II).

2. The weight ratio of the colorant mixture (II) is (C1) / (C
2) The production method according to the above 1, wherein the production is adjusted in a range of 95/5 to 5/95.

3. 3. The method according to 1 or 2, wherein the coloring agent (C) is a conductive coloring agent. 4. 4. The method according to the above 1, 2 or 3, wherein the self-water dispersible resin (A) is a resin having a neutralized acid group in an amount of 4 to 300 mg equivalent per 100 g of resin solids.

5. The method according to claim 1, wherein the self-water-dispersible resin (A) is at least one self-water-dispersible resin selected from acrylic, polyester, urethane, and epoxy resins.

Next, a preferred embodiment of the present invention will be described.
Organic solvent (B1) solution of carboxyl group-containing styrene / (meth) acrylate copolymer [resin (A ′)] having a weight average molecular weight of 150,000 to 150,000, an acid value of 30 to 150, and a glass transition temperature of 50 to 80 ° C. 3 to 40 parts by weight of a conductive colorant powder [colorant (C)] having a pH of 7.5 or more and an average primary particle diameter of 20 to 40 nm per 100 parts by weight of the resin nonvolatile matter, and a pH of 6.5 or less. Average particle diameter of primary particles of 20 to
After adding a conductive colorant powder [colorant (C)] of 40 nm, an alkali metal hydroxide aqueous solution and a surface tension-reducing organic solvent (B2) which is more hydrophilic than the organic solvent (B1) are added thereto. To make the resin (A ′) a resin (A) having a salt in a neutralized state of 4 to 200 mg per 100 g of resin solid content, and a solvent (B1) / (B2)
= 99/1 to 51/49 to give a mixture (I).

Water having the same temperature as that of the mixture (I) is added dropwise to the stirred mixture (I) at 15 to 25 ° C., and the mixture is phase-inverted and emulsified. The average particle size dispersed or contained in the water-dispersible resin (A) is 5
To obtain an aqueous dispersion of toner particles of about 20 μm.

After the organic solvent was distilled off from the aqueous dispersion, the toner was separated by filtration and dispersed again in water. An aqueous solution of hydrochloric acid is added thereto and stirred to convert the resin (A) on the surface of the toner particles into a resin (A ′). Then, this is filtered off, dispersed again in water, washed and filtered off. The obtained product is dried to obtain a dry powder toner for developing an electrostatic charge image composed of spherical particles having an average particle diameter of 5 to 20 μm.

Using this toner as a carrier, a toner concentration of 1 to
A two-component developer is prepared by mixing uniformly to 5% by weight.

[0089]

Next, the present invention shown in the preferred embodiment will be described more specifically with reference examples, examples and comparative examples. In the following, parts and%
Are based on weight unless otherwise noted.

Reference Example 1 650 parts of methyl ethyl ketone was put into a reactor and heated to 80 ° C. The mixture in the proportions indicated below was then added dropwise over a period of about 4 hours. Meanwhile, the reaction was performed in a stream of nitrogen.

Acrylic acid 77 parts Styrene 600 parts 2-Ethylhexyl acrylate 143 parts Methyl methacrylate 180 parts “Perbutyl O” (manufactured by NOF CORPORATION) 8 parts Methyl ethyl ketone 20 parts

Four hours after the completion of the dropwise addition of the above mixture,
4 parts of “perbutyl O” was added to the reaction solution,
After that, every 4 hours, 4 parts of “perbutyl O” was added, and the reaction was continued at 80 ° C. for 24 hours after the completion of the dropwise addition.

After the completion of the reaction, the weight average molecular weight was 5000
A solution of a copolymer having an acid value of 0 and an acid value of 60 was obtained. The present resin is an acrylic resin corresponding to the resin (A ′) that can become a self-water dispersible resin by neutralization in the present invention.

Example 1 (Preparation of 1-a Mixture A) 6 of the acrylic resin obtained in Reference Example 1 and adjusted to a non-volatile content of 50%, which can be a self-water dispersible resin
In 90 parts, 8 parts of carbon black powder "ELFTEX-8 (manufactured by Cabot Corporation)" (hereinafter referred to as carbon C1) having a primary particle average diameter of 30 nm at pH 8.5 and a primary particle average diameter of 30 nm at pH 2.4.
Carbon black powder `` Rarven1040 (Columbian
(Carbon C2) 32
"Eiger Motor Mill M-250"
[Eiger Japan Co., Ltd.] mixed for 1 hour. Hereinafter, this is abbreviated as mixture A.
The nonvolatile content of the mixture A was 57% by weight.

(1-b Preparation of Toner A) This mixture A
And 5.6 of a 1N aqueous solution of sodium hydroxide.
7 parts and 15 parts of isopropyl alcohol were added, and the mixture was preliminarily stirred at 350 rpm for several minutes using a three-one motor to obtain a mixture (I) according to the present invention. To this, 250 mL of distilled water was slowly added dropwise to emulsify the phase.

After removing the organic solvent by distillation under reduced pressure and filtering off from the processing solution, the particles were redispersed in water. Subsequently, the pH of the solution was adjusted to 2 with a 0.1N aqueous hydrochloric acid solution, and the mixture was stirred for 30 minutes to convert the resin in the toner particles into a resin capable of becoming self-water dispersible by neutralization. After the obtained particles were separated by filtration, an operation of redispersion and washing in water was performed, and then the particles were separated from the aqueous medium by filtration. This was freeze-dried to obtain the desired black toner powder (A).

The average particle size of the toner obtained here was 7.
It had a good distribution of 8 microns (μm), weight average particle diameter / number average particle diameter (d) = 1.2. Coulter Multisizer 2 was used to measure the particle size of the toner.

Further, the obtained toner is coated with a ferrite carrier coated with a silicon resin [manufactured by Powder Tech Co., Ltd.].
Was added so that the toner concentration became 3% to prepare a two-component developer. Using this developer, the charge amount was measured by a blow-off method.
0.3 μC / g, and the value at 30 minutes was −22.5 μC / g.
The charge amount distribution of the toner 60 minutes after charge-up was measured using "E-SPART" manufactured by Hosokawa Micron Corporation. The ratio of the reverse charge toner was 3.56%, and the standard deviation of the charge amount distribution was 1%. .22.

Example 2 (Preparation of Toner B) Example 1-a was carried out using an acrylic resin obtained in Reference Example 1 and adjusted to a non-volatile content of 50% and capable of becoming a self-water dispersible resin. Carbon C in the same manner as
1 and 16 parts of carbon C2, each mixture B
Was prepared.

Using this mixture B, the above Example 1-b
In the same manner as in the above, toner particles were prepared. The amount of the 1N aqueous sodium hydroxide solution and the amount of isopropyl alcohol were slightly finely adjusted. The shape of each of the obtained toners was spherical. Table 1 shows the charging characteristics of the obtained toner B.

Comparative Examples 1 and 2 (Preparation of Toners C and D) Hereinafter, using the acrylic resin obtained in Reference Example 1 and adjusted to a nonvolatile content of 50%, which can be a self-water dispersible resin, was carried out. Carbon C in the same manner as in Example 1-a
Mixtures C and D were prepared using 1 and C2, respectively.

Using the mixtures C and D, toner particles were prepared in the same manner as in Example 1-b. The amount of the 1N aqueous sodium hydroxide solution and the amount of isopropyl alcohol were slightly finely adjusted. Obtained toner C
Table 1 shows the charging characteristics of D and D.

[0103]

[Table 1]

As can be seen from Table 1, a mixture of a high pH carbon black powder, a styrene / (meth) acrylate ester copolymer in which a carboxyl group was neutralized with sodium hydroxide, and a colorant containing carbon black were used. The resulting toners of Examples 1 and 2 were prepared by mixing carbon black powder and styrene having a carboxyl group neutralized with sodium hydroxide.
Compared with the toners obtained by the production methods of Comparative Examples 1 and 2 using a mixture in which a (meth) acrylate ester-based copolymer is combined, the rise of charge is faster, the amount of reversely charged toner is small, and the distribution is sharp. It is clear that.

[0105]

According to the first aspect of the present invention, a colorant (C2) having the same polarity as the colorant (C1) having the opposite polarity as the colorant (C) is used as the base resin for obtaining the self-water dispersible resin. By using the mixture (II) of (1), the colorant is fixed near the particle surface to obtain a microencapsulated toner having a sharp charge amount distribution required for high-quality copying and a high charge speed. It has a particularly remarkable effect.

Claims (5)

[Claims] 1. A self-water-dispersible resin (A) obtained by neutralizing a resin (A ′) that can be made self-water-dispersible by neutralization with a neutralizing agent, and an organic solvent that dissolves the resin (A). Solvent (B)
And a mixture (I) containing a coloring agent (C) as an essential component,
After phase inversion emulsification in an aqueous medium to generate particles of the self-water dispersible resin in which the colorant (C) is encapsulated,
In the method for producing a capsule-type toner in which the particles are separated and dried, the resin (A ′) is used as a colorant (C).
A method for producing a capsule type toner, characterized by using a mixture (II) of a coloring agent (C1) having the opposite polarity to that of the coloring agent (C1) and a coloring agent (C2) having the same polarity. 2. The weight ratio of the colorant mixture (II) is (C1) / (C
2) The method according to claim 1, wherein the production is adjusted in the range of 95/5 to 5/95. 3. The method according to claim 1, wherein the colorant (C) is a conductive colorant. 4. The method according to claim 1, wherein the self-water dispersible resin (A) is a resin having a neutralized acid group in an amount of 4 to 300 mg equivalent per 100 g of resin solid content. 5. The method according to claim 1, wherein the self-water-dispersible resin (A) is at least one kind of self-water-dispersible resin selected from acrylic, polyester, urethane, and epoxy resins.