JP2007127729A - Method for manufacturing electrostatic charge image developing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrostatically charged image developing toner, which provides an image of high picture quality. <P>SOLUTION: The method for manufacturing toner includes: an aggregation step (1) of forming particle aggregates by causing coaggregation in a dispersion liquid which contains polymer primary particles obtained by mixing and dispersing an emulsion polymerized latex and at least a colorant; an aging step (2) of causing fusion bonding among aggregated particles in the dispersion liquid containing the particle aggregates; and a water washing step (3) of washing the aged particle aggregates with water. The aggregation step (1) is carried out in the presence of an electrolyte, the ageing step (2) is carried out in the presence of an emulsifier containing a sulfur element, and the water washing step (3) is carried out in a plurality of times so as to reduce a sulfur content in the obtained toner to 0.3 wt.% or less. The provided toner shows no degradation of picture quality with changes in charges under high temperature/high humidity conditions, and reduces so-called PC fog. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an electrostatic charge image developing toner. More particularly, the present invention relates to a method for producing a toner for developing an electrostatic image used in an electrophotographic copying machine and printer. More specifically, the present invention relates to a method for producing a toner for developing an electrostatic charge image that can obtain a high-quality image.

  When a visible image is formed by electrophotography, an electrostatic latent image is first formed on a photosensitive drum, then developed with toner, transferred to transfer paper, and then fixed by heat or the like. A visible image is formed.

  Conventionally, generally used toner is a styrene / acrylate copolymer produced by various methods or a binder resin such as polyester and a colorant, and if necessary, a charge control agent, a magnetic material, etc. are dry-typed. After mixing, melt kneading with an extruder or the like, followed by pulverization and classification, a method of obtaining a toner, so-called melt kneading pulverization method has been used.

  On the other hand, in recent years, high performance and high speed have been demanded as performance that printers and copiers should have. In order to achieve high image quality, it is necessary that the average particle diameter of the toner is substantially 10 μm or less, particularly about 3 to 8 μm, and that the particle size distribution is narrow. In order to achieve high speed, low temperature fixability is required.

  However, in the conventional toner obtained by the melt-kneading pulverization method, it is difficult to control the particle size of the toner at the time of manufacture. A large amount of fine powder having a desired particle size or less was by-produced, and it was difficult to eliminate this by a classification step. In addition, a low softening point resin needs to be blended in order to produce a low-temperature fixing toner, but a low softening point resin that impedes brittleness because the toner production process by the melt-kneading pulverization method has a pulverization process. The use of was impossible.

  As a method of improving the disadvantages of the melt-kneading and pulverizing method, a mixture of a polymerizable monomer, a colorant, a polymerization initiator and the like is suspended and dispersed in an aqueous medium to form droplets having a suitable particle size, and then polymerization is performed. There has been proposed a suspension polymerization method in which toner particles are obtained. There has also been proposed an emulsion polymerization method in which toner particles are obtained by adding a colorant and optionally a charge control agent to an emulsion of polymer primary particles obtained by emulsion polymerization, and aggregating and aging. When a toner is obtained by a manufacturing method called a polymerization method, since the particle size can be easily controlled, a toner having a small particle size and a narrow particle size distribution can be obtained, and a pulverization step is unnecessary, so that a low softening point is obtained. A toner using a resin can be manufactured, and a toner excellent in high resolution and low-temperature fixability can be obtained.

  The toner produced by the polymerization method as described above can be fixed at low temperature, but problems such as blocking may occur when the toner is stored. In order to solve this problem, it has been proposed to produce encapsulated toner by producing fine particles having a low softening point by suspension polymerization and attaching a resin having a high softening point to the surface in an aqueous medium. Yes. In addition, an encapsulated toner in which an outer layer of a polymer is formed on the surface of agglomerated / ripened particles produced by an emulsion polymerization method has also been proposed, and generally shows excellent performance. In addition, in the case of polymerized toners by suspension polymerization or emulsion polymerization, it has been proposed to control the acid value and the like of the binder resin by copolymerizing several percent of monomers having Bronsted acidic groups typified by organic carboxylic acids. (For example, refer to Patent Document 1).

  Since the binder resin having a Bronsted acidic group has a hygroscopic property based on the acidic group, when exposed to high temperature and high humidity, the chargeability of the toner particles changes due to the moisture absorption, which tends to adversely affect the image quality. Specifically, in the emulsion polymerization method, if a monomer component having a specific amount or more, for example, 3% by weight or more, is included in the monomer component constituting the polymer primary particle, the acid value is controlled and aggregation / ripening is performed. Although the particle size could be controlled in the process, when an image is formed using the obtained toner, charging changes at high temperatures and high humidity occur, resulting in an adverse effect on image quality. There is a need for a technique that can solve the contradictory state of particle size controllability in the aggregation process.

As one of the solutions, co-aggregation is caused in a dispersion containing polymer primary particles obtained by mixing and dispersing at least a colorant with an emulsion polymerization latex containing polymer primary particles obtained by emulsion polymerization. In the toner production method, the coagulation step and the aging step include an aggregation step for generating particle aggregates and a ripening step for causing fusion between the aggregated particles in the dispersion containing the particle aggregates obtained in the aggregation step. A method in which a zero-valent or divalent iron element and a trivalent salt are present in at least one of the steps has been proposed (see Patent Document 2).
JP 2002-278153 A Japanese Patent Laid-Open No. 2004-294751

  According to the invention of Patent Document 2, the problems of deterioration in image quality due to a change in charge amount under high temperature and high humidity and controllability in the aggregation process are solved. Based on this technology, the present inventor has conducted extensive research to further reduce PC fog and obtain an excellent toner. As a result, the existence of sulfur components remaining in the toner has a close relationship. I knew it. An emulsifier containing a sulfur component is effective for redispersion of aggregated particles (preventing agglomeration) and is indispensable for use in the aging process, but the residual amount can be reduced by combining specific water washing processes. The present invention has been completed by knowing that it can be reduced.

  That is, the gist of the present invention is an aggregation step (1) in which coagulation is caused in a dispersion containing polymer primary particles obtained by mixing and dispersing an emulsion polymerization latex and at least a colorant to produce particle aggregates. And a ripening step (2) for causing fusion between the agglomerated particles in the dispersion containing the particle agglomerates, and a water washing step (3) for washing the aged particle agglomerates with water. In the production method, the aggregation step (1) is performed in the presence of an electrolyte, the aging step (2) is performed in the presence of an emulsifier containing a sulfur element, and the water washing step (3) is performed a plurality of times. The present invention resides in a method for producing an electrostatic charge image developing toner, characterized in that the sulfur content in the obtained toner is 0.3% by weight or less.

  Moreover, the following preferable embodiment can be mentioned as another summary of this invention.

  The method for producing a toner for developing an electrostatic image as described above, wherein the sulfur content is 0.2% by weight or less.

  The method for producing a toner for developing an electrostatic image as described above, wherein the sulfur content is 0.1% by weight or less.

  The method for producing a toner for developing an electrostatic charge image, wherein the electrolyte used in the aggregation step (1) is a sulfate.

  The method for producing an electrostatic charge image developing toner as described above, wherein the sulfur element-containing emulsifier used in the aging step (2) is an alkylbenzene sulfonate.

  The electrostatic charge image described above, wherein the amount of the emulsifier containing the sulfur element used in the aging step (2) is 1 to 20 parts by weight with respect to 100 parts by weight of the latex solid content and the colorant in total. A method for producing a developing toner.

  The method for producing a toner for developing an electrostatic charge image, wherein the aging step (2) is performed in the presence of an alkali.

  The aging step (2) is performed at a temperature of 80 ° C. higher than the glass transition temperature or glass transition temperature of the polymer in the latex, and the temperature rise from the aggregation step (1) to the aging step (2) is 0.1. The method for producing a toner for developing an electrostatic charge image as described above, which is carried out in a range of -3 ° C / min.

  The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein at least one of the plurality of water washing steps (3) is performed in the presence of an alkali.

  The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein at least one of the plurality of water washing steps (3) is performed in the presence of an acid.

  The method for producing a toner for developing an electrostatic charge image described above, which is carried out under a condition that the electrical conductivity of the final washing liquid in the water washing step (3) carried out a plurality of times is 1.5 μS / cm or less.

Hereinafter, embodiments of the present invention will be described in detail.
The present invention is a method for producing a polymerized toner by an emulsion polymerization method. Basically, an emulsion polymerization step for obtaining an emulsion polymerization latex containing polymer primary particles by emulsion polymerization, a colorant in the obtained emulsion polymerization latex, and A coagulation step (1) in which coagulation is caused in a dispersion containing polymer primary particles obtained by adding and dispersing a charge control agent, wax, and other additives as necessary, to form particle aggregates; A ripening step (2) for generating toner particles by causing fusion between the agglomerated particles in the particle agglomerate in the dispersion containing the particle agglomerate obtained in the agglomeration step, and separating and washing the aged agglomerated particles It is comprised from the water washing process (3) for doing. The encapsulated toner can also be produced by attaching or fixing resin fine particles to the particle aggregate in the stage after the aggregation process.

First, the emulsion polymerization process will be described.
In the emulsion polymerization step, by sequentially adding the monomer to the aqueous medium containing the emulsifier, the polymerization of the monomer proceeds in the emulsion to produce an emulsion polymerization latex (dispersion) containing the polymer primary particles. To do. As the emulsifier, a known surfactant such as a cationic surfactant, an anionic surfactant, or a nonionic surfactant is used. Two or more of these surfactants may be used in combination. The amount of emulsifier used is not uniform depending on the type of emulsifier, the type of polymerizable monomer, the concentration, etc., but is usually in the range of 0.1 to 5 parts by weight per 100 parts by weight of the polymerizable monomer. Some emulsifiers used in emulsion polymerization contain a sulfur element-containing compound. In order to keep the amount of the compound remaining in the toner to a small amount, an aging step (2) and a water washing step (3) described later are used. ) Is necessary to control.

  Specific examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like.

  Specific examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

  Furthermore, specific examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, etc. Is mentioned.

  When the wax is contained in the toner particles, the wax may be added in the aggregation step (1), but a method of adding in the emulsion polymerization step so that the polymer primary particles themselves contain the wax is also preferable. Examples of the method include seed emulsion polymerization of a monomer mixture using wax fine particles obtained by emulsification in the presence of an emulsifier as a seed, and a method of dissolving a wax in a monomer and emulsion polymerization of the monomer. .

  As said wax, arbitrary things can be used from well-known waxes. Specifically, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene and copolymer polyethylene; paraffin wax; ester waxes having long chain aliphatic groups such as behenyl behenate, montanate ester, stearyl stearate; hydrogenated Plant waxes such as castor oil and carnauba wax; ketones having long chain alkyl groups such as distearyl ketone; silicone waxes having alkyl groups; higher fatty acids such as stearic acid; long chain aliphatic alcohols such as eicosanol; glycerin and penta Examples include polyhydric alcohol carboxylic acid esters or partial esters obtained from polyhydric alcohols such as erythritol and long chain fatty acids; higher fatty acid amides such as oleic acid amides and stearic acid amides; low molecular weight polyesters.

  The monomer to be subjected to emulsion polymerization is selected according to the purpose and is not particularly limited, but is preferably a monomer having a Bronsted acidic group (hereinafter sometimes simply referred to as an acidic group) or a Bronsted basic group (hereinafter simply referred to as a simple group). A monomer having a basic group) and a monomer having neither a Bronsted acidic group nor a Bronsted basic group (hereinafter also referred to as other monomer). These monomers may be added separately, or may be added after mixing a plurality of monomers in advance. Furthermore, it is possible to change the monomer composition while the monomer addition is continued. The monomer may be added as it is, or may be added as an emulsion prepared by mixing with water or an emulsifier in advance. As the emulsifier in this case, one or two or more combined systems are selected from the above surfactants.

  Examples of the monomer having the Bronsted acidic group include monomers having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and cinnamic acid, monomers having a sulfonic acid group such as sulfonated styrene, and vinylbenzenesulfonamide. And monomers having a sulfonamide group such as a monomer having a carboxyl group are preferable, and acrylic acid or methacrylic acid is particularly preferable.

  Examples of the monomer having a Bronsted basic group include aromatic vinyl compounds having an amino group such as aminostyrene, nitrogen-containing heterocycle-containing monomers such as vinylpyridine and vinylpyrrolidone, dimethylaminoethyl acrylate, and diethylaminoethyl methacrylate. And (meth) acrylic acid ester having an amino group.

  The monomer having an acidic group and the monomer having a basic group may each exist as a salt with a counter ion. The blending ratio of the monomer having a Bronsted acidic group or Bronsted basic group in the monomer mixture constituting the polymer primary particles is preferably 0.01% by weight or more, more preferably 0.5% by weight or more. And preferably 5% by weight or less, more preferably less than 3% by weight. In particular, it is preferable to use a monomer having a Bronsted acidic group, and a more preferable blending ratio of the monomer having an acidic group is 3% by weight or less.

  Examples of the other monomers include styrenes such as styrene, methylstyrene, chlorostyrene, dichlorostyrene, pt-butylstyrene, pn-butylstyrene, pn-nonylstyrene, methyl acrylate, acrylic Ethyl acetate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid (Meth) acrylic acid esters such as hydroxyethyl and ethylhexyl methacrylate, acrylamide, N-propylacrylamide, N, N-dimethylacrylamide, N, N-dipropylacrylamide, N, N-dibutylacrylate And acrylic acid amides such as Ruamido. Of these, styrene, butyl acrylate and the like are particularly preferable.

  The resin used for the polymer primary particles is preferably a crosslinked resin. Crosslinking is performed by blending a monomer having at least two functional groups (polyfunctional monomer) into the emulsion polymerization system.

  In this case, a polyfunctional monomer having radical polymerizability is used as a cross-linking agent shared with the above-mentioned monomer, for example, divinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate. , Triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol acrylate, diallyl phthalate, and the like. A monomer having a reactive group in a pendant group, such as glycidyl methacrylate, methylol acrylamide, or acrolein, can be used.

  The blending ratio of the polyfunctional monomer in the monomer mixture is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, still more preferably 0.05% by weight or more, and preferably 5%. % By weight or less, more preferably 3% by weight or less, still more preferably 1% by weight or less. Further, the tetrahydrofuran (THF) insoluble content of the toner is preferably 15 to 80% by weight, and preferable values of the storage elastic modulus G ′ and loss elastic modulus G ″ at 200 ° C. in the dynamic viscoelasticity measurement of the toner are both 400 Pa or more, more preferably 800 Pa or more, still more preferably 1000 Pa or more.

  These monomers are used alone or in combination, and at that time, the glass transition temperature of the polymer primary particles is preferably 40 to 80 ° C. If the glass transition temperature exceeds 80 ° C., the fixing temperature may become too high, or the deterioration of OHP transparency may be a problem. On the other hand, if the glass transition temperature of the polymer is less than 40 ° C., the toner storage stability May be worse.

  In the method of the present invention, a known water-soluble polymerization initiator can be used as a polymerization initiator when performing emulsion polymerization. For example, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, and redox initiators combining these persulfates as a component with a reducing agent such as acidic sodium sulfite, hydrogen peroxide, 4,4′- A water-soluble polymerization initiator such as azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydroperoxide, and the like, a redox initiator system in which these water-soluble polymerization initiators are combined with a reducing agent such as ferrous salt as a component, Benzoyl oxide, 2,2′-azobisisobutyronitrile and the like are used. These polymerization initiators may be added to the polymerization system before, simultaneously with the addition of the monomer, or after the addition, and these addition methods may be combined as necessary. Among the above, persulfate, acidic sodium sulfite, and the like contain sulfur element and may remain in the toner. Therefore, it is preferable not to use a polymerization initiator containing a sulfur element. When used, it is important to limit the amount. Otherwise, it is necessary to sufficiently remove the sulfur-containing compound in the water washing step (3) described later.

  In the present invention, a known chain transfer agent may be used as necessary. For example, t-dodecyl mercaptan, 2-mercaptoethanol, diisopropylxanthogen, carbon tetrachloride, trichlorobromomethane and the like can be mentioned. The chain transfer agent may be used alone or in combination of two or more, and is usually used in the range of 0 to 5 parts by weight with respect to 100 parts by weight of the monomer. Of the above, mercaptan-based chain transfer agents function extremely effectively as chain transfer agents. In the present invention, as described later, it is basically possible to control the sulfur content in the toner to a specific value or less. Since it is important, it is preferable to limit the amount used. Otherwise, it is necessary to sufficiently remove the sulfur-containing compound by paying special attention in the water washing step described later.

  The volume average particle diameter of the polymer primary particles obtained as described above is usually in the range of 0.02 to 3 μm, preferably 0.05 to 3 μm, more preferably 0.1 to 2 μm. Preferably it is 0.1-1 micrometer. The volume average particle diameter can be measured, for example, by using “Microtrac UPA (ultra particle analyzer)” (hereinafter referred to as UPA) manufactured by Nikkiso. If the particle size is too small, it is difficult to control the aggregation rate. On the other hand, if the particle size is too large, the toner particle size obtained by agglomeration becomes large, so that it tends to be inappropriate for applications requiring high resolution as a toner.

Next, the aggregation step (1) of the present invention will be described.
In the aggregation step, the polymer primary particles, the colorant primary particles, and, if necessary, the charge control agent fine particles, wax fine particles, and other internal additives are emulsified to form an emulsion, and these are co-aggregated. Particle aggregates are used. Among the components that perform aggregation, the charge control agent dispersion may be added during the aggregation process or after the aggregation process.

  Specific examples of the colorant include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dye, pigment, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dye, monoazo Any known pigments such as disazo dyes and condensed azo dyes can be used alone or in combination. In the case of a full color toner, it is preferable to use benzidine yellow for yellow, monoazo and condensed azo dyes, magenta for quinacridone and monoazo dyes, and cyan for phthalocyanine blue. The colorant is usually used in an amount of 3 to 20 parts by weight with respect to 100 parts by weight of the binder resin. In the present specification, the amount of the “binder resin” means the amount of the resin component constituting the polymer primary particles and the resin component constituting the resin fine particles combined when the resin fine particles described later are used.

  The colorant primary particles are preferably those in which an organic pigment that is substantially insoluble in water is emulsified in water in the presence of an emulsifier to form an emulsion. In this case, the volume average particle diameter of the colorant primary particles Is preferably 0.01 to 3 μm.

  As the charge control agent, any known one can be used alone or in combination. Examples of the charge control agent include a quaternary ammonium salt and a basic / electron-donating metal substance as a positive charge control agent. As a negatively chargeable charge control agent, metal chelates, organic acid metal salts, metal-containing dyes, nigrosine dyes, amide group-containing compounds, phenol compounds, naphthol compounds and their metal salts, urethane bond-containing compounds, acidic or electronic Inhalable organic substances are mentioned.

  In consideration of adaptability to the color toner (the charge control agent itself is colorless or light and there is no color tone problem on the toner), a quaternary ammonium salt compound is used as the positive charge control agent, and a negative charge control agent. As metal salts and metal complexes of salicylic acid or alkylsalicylic acid with chromium, zinc, aluminum, etc., metal salts of benzylic acid, metal complexes, amide compounds, phenol compounds, naphthol compounds, phenolamide compounds, 4,4′-methylenebis Hydroxynaphthalene compounds such as [2- [N- (4-chlorophenyl) amide] -3-hydroxynaphthalene] are preferred. The amount of use may be determined by the desired charge amount for the toner, but usually 0.01 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, is used with respect to 100 parts by weight of the binder resin.

  The charge control agent is also preferably used in water as an emulsion (charge control agent primary particles) having an average particle size of 0.01 to 3 μm.

  The aggregation step (1) of the present invention is performed by adding an electrolyte to the emulsion polymerization latex according to a known method. As such an electrolyte, a zero-valent or divalent iron element and a trivalent salt are preferably used. When the electrolyte is not added in the aggregation step, the latex is incompletely aggregated and the aging step (2) described later cannot be carried out smoothly. In the electrolyte component, there is a compound containing a sulfur element such as a sulfate. When such a compound is used, the amount remaining in the toner is determined in the same manner as the sulfur compound of the chain transfer agent or the polymerization initiator. It is necessary to consider the reduction.

  The zero-valent iron element is generally iron in a metallic state, but specific examples include iron powder to increase the surface area per volume, and examples of divalent iron include iron sulfate, iron chloride, and iodide. Examples thereof include inorganic salts of divalent iron such as iron, and organic salts of divalent iron such as iron gluconate, iron lactate, iron naphthenate, and iron oxalate. Of these, inorganic salts, particularly iron sulfate, are preferred. In order to exert the effects of the present invention, the zero-valent or divalent iron element is preferably contained in the latex in an amount of 1 ppm by weight or more, particularly 10 ppm by weight or more, more preferably 20 ppm by weight or more. Is preferred. Moreover, since the effect is saturated even if the content of the iron element is excessive, it is preferably 500 ppm by weight or less, particularly preferably 300 ppm by weight or less.

Examples of the trivalent salt include inorganic salts such as Al ₂ (SO ₄ ) ₃ and Fe ₂ (SO ₄ ) ₃ , and organic substances such as (CH ₃ COO) ₃ Fe and (C ₆ H ₅ SO ₃ ) ₃ Fe. Among them, inorganic salts are preferable from the viewpoint of effects, and Al ₂ (SO ₄ ) ₃ is particularly preferable. Examples of electrolytes that can be used in addition to zero-valent or divalent iron elements and trivalent salts include MgSO ₄ , MgCL ₂ , CaCL ₂ , CaSO ₄ , ZnSO ₄ , NaCL, KCL, LiCL, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO _{4 and the} like can be mentioned. Of these, sulfate is preferred.

  The content of the electrolyte in the latex varies depending on the type of electrolyte, but is usually 0.05 parts by weight or more, particularly 0.1 parts by weight or more with respect to 100 parts by weight of the solid component of the mixed latex. Is preferably 0.2 parts by weight or more. Moreover, since an effect is saturated even if it is excessive, the amount is preferably 25 parts by weight or less, particularly preferably 15 parts by weight or less, and further preferably 10 parts by weight or less.

  When the amount of electrolyte added is significantly less than the above range, the progress of the agglomeration reaction is delayed, and fine powder of 1 μm or less remains after the agglomeration reaction, or the average particle diameter of the obtained agglomerated particles is 3 μm or less, which is smaller than desired. It tends to cause problems such as becoming. In addition, when the amount of electrolyte added is significantly larger than the above range, agglomeration that is quick and difficult to control is likely to occur, and coarse particles of 25 μm or more are mixed in the obtained agglomerated particles, or the shape of the agglomerates is irregular. It tends to cause problems such as becoming an irregular shape.

  The method of mixing the emulsion polymerization latex, the electrolyte and other components is not particularly limited, but the electrolyte is first mixed with the latex, and then the colorant primary particles, the charge control agent particles, the wax fine particles, and the like. A method of agglomerating by adding an additive is preferred. It is better to first contact the iron element directly with the emulsion polymerization latex containing the polymer primary particles obtained by emulsion polymerization, and the effect tends to be reduced if the iron element is added after mixing with other components such as a colorant. is there.

  Furthermore, in the present invention, it is preferable that a thermally decomposable radical generator is present in the aggregation step (1). It is because there exists an effect | action which reduces content of the unreacted monomer which remains in latex. More preferably, it is present in the agglomeration step (1) and as it is without separation in the aging step (2). As the thermally decomposable radical generator, a known water-soluble polymerization initiator that is usually used as a polymerization initiator can be used. Specifically, for example, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, and redox initiators that combine these persulfates as a component with a reducing agent such as acidic sodium sulfite, hydrogen peroxide, 4 , 4'-azobiscyanovaleric acid, t-butyl hydroperoxide, cumene hydroperoxide, and other water-soluble polymerization initiators, and redox in which these water-soluble polymerization initiators are combined with reducing agents such as ferrous salts as one component Initiator systems, benzoyl peroxide, 2,2′-azobisisobutyronitrile and the like are used. Of these, persulfate is preferable. The amount of the thermally decomposable radical generator added is usually 0.1 to 3% by weight, preferably 0.3 to 2% by weight, more preferably 0.00%, based on the polymer component in the particle aggregate-containing dispersion. 4 to 1% by weight.

  Specifically, as the aggregation temperature in the aggregation step, a temperature range of 5 to Tg ° C. (where Tg is the glass transition temperature of the polymer primary particles) is preferably used, and (Tg-10) to (Tg-5) ° C. The range of is preferable. If it is the said temperature range, it can usually aggregate to a preferable toner particle size.

  Aggregation is preferably carried out at a predetermined temperature for usually at least 30 minutes to form toner particles having a desired particle diameter. The temperature may be increased at a constant rate up to a predetermined temperature, or may be increased stepwise. The holding time is preferably from 30 minutes to 8 hours in the range of (Tg-20) to Tg ° C, and more preferably from 1 hour to less than 4 hours. By doing so, a toner having a small particle size and a sharp particle size distribution can be obtained.

  In the aggregating step, a normal stirring tank is used, and the shape is preferably a substantially cylindrical shape or a substantially spherical shape. When the shape of the reaction vessel is substantially cylindrical, the shape of the bottom surface is not particularly limited, but a normal substantially arc shape is preferably used.

  In order to improve the stirring efficiency, the volume of the mixed dispersion is preferably 2/3 or less, more preferably 3/5 or less of the volume of the reaction vessel. In addition, if the volume of the mixed dispersion is extremely small compared to the volume of the reaction vessel, foaming is intense and thickening increases, coarse powder particles are likely to be generated, and depending on the shape of the stirring blade, stirring may not be possible. Since the production efficiency also decreases, this ratio is preferably 1/10 or more, and more preferably 1/5 or more.

  As the stirring blade used in the aggregation process, known various shapes of stirring blades can be used. Examples of commercially available stirring blades include anchor blades, full zone blades (manufactured by Shinko Pantech Co., Ltd.), sun meller blades (manufactured by Mitsubishi Heavy Industries, Ltd.), max blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), Hi-F mixer blades (soken) And a stirring blade such as a double helical ribbon blade (manufactured by Shinko Pantech Co., Ltd.). Moreover, you may provide a baffle in a stirring tank. Usually, from these stirring blades, suitable ones are selected and used depending on the viscosity and other physical properties of the reaction liquid, the reaction form, the shape and size of the reaction tank, etc. Includes a double helical ribbon wing or an anchor wing, and among them, a double helical ribbon wing is more preferable.

  If any means for reducing unreacted monomer is not taken during the agglomeration step, unreacted monomer equivalent to that in the emulsion polymerization latex remains in the resulting particle aggregate-containing dispersion. Become. The particle aggregate-containing dispersion to be used in the aging step (2) described later usually contains 50 to 3000 ppm of unreacted monomer with respect to the polymer component therein.

Next, the aging step (2) will be described.
In the aging step, toner particles are generated by causing fusion between the aggregated particles in the particle aggregate in the dispersion containing the particle aggregate obtained in the aggregation step (1). This is performed in order to increase the stability of the particle aggregate obtained in the aggregation step. When the dispersion containing the particle aggregate to be subjected to the ripening step contains an appropriate amount of unreacted monomer, the shape of the toner particles obtained in the ripening step can be easily made nearly spherical, Shape control is also easy.

  The temperature of the aging step (2) is selected from the temperature range of Tg to (Tg + 80) ° C., preferably (Tg + 20) to (Tg + 80) ° C., but preferably about 5 to 80 ° C. than the temperature of the aggregation step (1). In particular, the temperature is increased by about 10 to 50 ° C. This is because fusion between the agglomerated particles is promoted and shape control is facilitated. In this case, it is preferable to raise the temperature gradually, for example, in the range of 0.1 to 3 ° C./min, particularly 0.5 to 2 ° C.

  The time for the aging step is usually 1 to 24 hours, preferably 1 to 10 hours. The aging step can be performed using a stirring tank similar to the stirring tank used in the aggregation process. Slowly aging for a long time is preferable because it has the effect of discharging the emulsifier penetrating the inside of the particle aggregate to the outside, but is selected from the above range for economical process control. .

  As described above, the dispersion containing the particle aggregate subjected to the aging step contains a considerable amount (usually 50 to 3000 ppm) of unreacted monomer. It can be easily removed by including a thermally decomposable radical generator in the dispersion containing the particle aggregate.

  When producing an encapsulated toner, resin fine particles are added to the particle aggregate-containing dispersion before or during the ripening step, and the resin fine particles are adhered or fixed to the particle aggregate. The resin fine particles are dispersed in water or a liquid mainly composed of water with an emulsifier and used as an emulsion. The resin fine particles are preferably those obtained by emulsion polymerization. The resin fine particles are preferably substantially free of wax. The phrase “substantially free of wax” means that the wax content in the resin fine particles is 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.1% by weight or less. . When the resin fine particles do not substantially contain wax, it is difficult for the wax to ooze to the toner surface before the toner is fixed by the fixing machine, so that the apparatus can be prevented from being soiled, and the blocking resistance is also good. Become.

  The resin fine particles preferably have a volume average particle size of 0.02 to 3 μm, more preferably 0.05 to 1.5 μm, and are obtained by polymerizing a monomer similar to the monomer used for the polymer primary particles described above. What was obtained can be used. The resin used for the resin fine particles is preferably crosslinked. As a crosslinking agent, the polyfunctional monomer used for the above-mentioned polymer primary particle can be used. In the case of using a crosslinked resin for the resin fine particles, the degree of crosslinking is usually 5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, and particularly preferably 20% by weight or more in terms of tetrahydrofuran insolubles. Moreover, it is 70 weight% or less normally.

  One of the important components of the present invention is that the aging step (2) is performed in the presence of an emulsifier containing a sulfur element. Examples of the emulsifier containing sulfur element include sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium 2-ethylhexyl sulfate, sodium 2-ethylhexyl benzene sulfonate, sodium 2-ethylhexyl sulfate and the like. Among these emulsifiers, alkylbenzene sulfonate is particularly preferable.

  An emulsifier containing a sulfur element is necessary to redisperse the particle aggregates in the aging atmosphere of the particle aggregates. If this is not present, latex agglomerates and the particle agglomerates tend to coalesce into a large mass. The amount of the emulsifier containing the sulfur element in the aging step (2) is 1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the total amount of the emulsion polymerization latex solids and the colorant. Controlled. When an emulsifier containing a sulfur element is used in carrying out the emulsion polymerization, the emulsifier moves directly to the aging step (2). If the amount of the emulsifier used during the emulsion polymerization is insufficient, it is necessary to newly add an emulsifier containing a sulfur element in the aging step (2). On the other hand, when an emulsifier containing a sulfur element is not used when performing emulsion polymerization, the emulsifier containing a sulfur element is used for the first time in the aging step (2). Accordingly, the amount of emulsifier used is determined in consideration of the relationship between the two, but usually there are many embodiments in which an emulsifier is added in the aging step (2).

  In the aging step (2), an alkali can be added. As the alkali, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium hydroxide, barium hydroxide, triethanolamine, triethylamine, trimethylamine, etc. are used, and the pH of the solution in which the particle aggregate after addition of the alkali is dispersed is used. 5 to 14 is preferable, and 6 to 9 is particularly preferable. In the ripening step (2), when the amount of alkali used is less than the above range, the surface potential of the particle aggregate is lowered and excessively aggregated to form coarse particles. On the other hand, when it exceeds the above range, the surface potential becomes high and it does not overaggregate but it is difficult to form a sphere. By setting the pH within the above range, the surface potential is increased, the particle dispersibility is stabilized, and the amount of emulsifier used to control particle aggregation can be reduced. The spheroidization also proceeds well.

Next, the water washing step (3) will be described.
The toner particles are recovered by separating, washing, and drying the solid component from the dispersion containing the particle aggregate that has undergone the aging step (2). A known method such as filtration or decantation can be used to collect the toner particles. An important feature of the present invention is that the separated toner particles are treated a plurality of times in the water washing step (3) using water. As the water used in the water washing step (3), demineralized water is usually used. Although demineralized water is preferably used for the final washing, other water washing can be appropriately performed in the presence of an acid or an alkali. As the acid, a strong acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid is used. Washing with an acid-containing water has an effect of suppressing dissociation of carboxyl groups in the binder resin constituting the toner. As the alkali, sodium hydroxide, potassium hydroxide, sodium carbonate, calcium hydroxide or the like is used. Washing with water containing alkali has an effect of neutralizing acidic groups present on the surface of the toner particles, improving affinity with water, and removing an emulsifier component contained in the toner.

  The use of acid and alkali is optional and may be not used. For example, when alkali is added in the aging step (2), only the demineralized water is used for the first several times, and once or twice in the middle. An embodiment in which acid washing is added and finally demineralized water is used several times is preferable. The first several times are washed with alkali, the pH of the filtrate is adjusted to 8-14, then washed with demineralized water, acid washed once in the middle, and finally demineralized water is used several times. .

  The water used in the water washing is usually 4000 parts by weight or more, preferably 10,000 parts by weight or more in total with respect to 100 parts by weight of solid content (toner particles). Dehydration-washing as one unit is repeated at least a plurality of times, usually 5 to 40 times, preferably 10 to 20 times.

  In the present invention, the sulfur content in the finally obtained toner is 0.3% by weight, preferably 0.2% by weight or less, more preferably 0.1% by weight or less. As a measure of water cleaning according to the above-described embodiment, it is preferable to control the electric conductivity of the final cleaning liquid to be in the range of 1.5 μS / cm, preferably 1.0 μS / cm.

  Further, the toner obtained by the method of the present invention can be used together with additives such as a fluidizing agent, if necessary. Specific examples of such fluidizing agents include hydrophobic silica, titanium oxide, and aluminum oxide. In general, it is used in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the binder resin.

  Further, the toner obtained by the method of the present invention contains an internal additive or a resistance modifier such as magnetite, ferrite, cerium oxide, strontium titanate, conductive titania, or a styrene resin, an acrylic resin, or a resistance regulator or lubricant. It can be used as an external additive. The amount of these additives to be used may be appropriately selected depending on the desired performance, and is usually about 0.05 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner for developing an electrostatic charge image of the present invention may be used in the form of a two-component developer or a magnetic or non-magnetic one-component developer, but a non-magnetic one-component developer is suitable. When used as a two-component developer, the carrier may be a magnetic substance such as iron powder, magnetite powder or ferrite powder, or a known material such as a resin coating on the surface thereof or a magnetic carrier. As the coating resin of the resin coating carrier, generally known styrene resin, acrylic resin, styrene acrylic copolymer resin, silicone resin, modified silicone resin, fluororesin, or a mixture thereof can be used.

  Next, specific embodiments of the present invention will be described in more detail with reference to Examples / Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist. In the following examples, “parts” means “parts by weight”. Moreover, physical property evaluation was measured by the following method, respectively.

<Average particle diameter / median diameter>
The average particle size of the latex liquid and the emulsion is measured with Nikkiso Microtrac (hereinafter abbreviated as UPA), and the average particle size of the toner is Coulter Counter Multisizer II type (hereinafter abbreviated as Coulter Counter) manufactured by Coulter. It was measured by.
<Sulfur content>
X-ray fluorescence analyzer: Rigaku ZSX Primus
Sample preparation method: Using a tablet-forming compressor, 5 g of sample powder is press-molded for 20 seconds under a pressure of 25 tons.
<Electric conductivity>
Device: Cyberscan conductivity meter CON 100, manufactured by ASONE
Measurement temperature: 25 ° C
Unit of measurement: μS (micro Siemens) / cm

<PC cover>
(1) After actually taking 10 sheets of 5% chart (chart corresponding to 5% of the entire image area), the toner remaining in the non-image area of the photoconductor is removed from Sukuchimen manufactured by Sumitomo 3M Limited. It was taken with a ding tape (trademark, width 18 mm, length 10 cm) and pasted on white paper.
(2) Next, the PC difference was defined as the color difference between the average hue of ten pasted mending tapes and the average hue of ten white hues. In addition, ΔE was measured according to the method described in the instruction manual using a hue meter (X-rite 900 series, manufactured by Japan Planographic Equipment Co., Ltd.).

△ Evaluation of PC fog at E value ○ Less than 1 Good level △ 1-3 Practical level × More than 3 Practical level

[Comparative Example 1]
(1) Production of Wax Emulsion 68.33 parts of demineralized water, 30 parts of an ester mixture mainly composed of tetraester stearate of pentaerythritol (“Unistar H476D” manufactured by NOF Corporation), sodium dodecylbenzenesulfonate (Daiichi Kogyo Seiyaku) 1.67 parts of “Neogen SC” (manufactured by Kogyo Co., Ltd., active ingredient 66%) were mixed and emulsified by applying high-pressure shear to obtain a dispersion of ester wax fine particles. The average particle diameter of the ester wax fine particles measured by UPA was 260 nm.

(2) Production of polymer dispersion 52.1 parts of the above wax emulsion in a reactor (volume: 3 liters) equipped with a stirrer (three blades), a heating / cooling device, a concentrating device and each raw material / auxiliary charging device, 353 parts of demineralized water was added, the temperature was raised to 70 ° C. under a nitrogen stream, and 3.2 parts of an 8% aqueous hydrogen peroxide solution and 3.2 parts of an 8% ascorbic acid aqueous solution were added. Thereafter, a mixture of the following monomers and an aqueous emulsifier solution was added over 5 hours from the start of polymerization. Further, the following initiator aqueous solution was added over 6 hours from the start of polymerization. The temperature was raised to 90 ° C. 30 minutes after the addition of the mixture of the monomers and the emulsifier aqueous solution, and after reaching 90 ° C., the mixture was held for 90 minutes.

<Monomers>
Styrene 75.6 parts Butyl acrylate 22.9 parts Acrylic acid 1.48 parts Trichlorobromomethane (chain transfer agent) 0.63 parts Hexanediol diacrylate (crosslinking agent) 0.7 parts <Emulsifier aqueous solution>
10% aqueous solution of sodium dodecylbenzenesulfonate (Daiichi Kogyo Seiyaku Co., Ltd., “Neogen SC”, active ingredient 66%) 2.0 parts Demineralized water 66.1 parts <Initiator aqueous solution>
8% hydrogen peroxide solution 18.9 parts 8% aqueous solution of ascorbic acid 18.9 parts After the completion of the polymerization reaction over 6 hours in total, the mixture was cooled to obtain a milky white polymer dispersion. The volume average particle diameter measured by UPA was 206 nm. The solid content concentration was 19.3% by weight.

(3) Production of Toner Slurry B A reactor (volume: 2 liters, anchor blade with baffle) was charged with 94.5 parts of the polymer dispersion obtained above, and stirred with a 5% FeSO ₄ .7H ₂ O aqueous solution. Was added over 1 minute such that the Fe element was 100 ppm with respect to the polymer dispersion. Thereafter, stirring was continued for 30 minutes to uniformly mix, and then 5.5 parts of the colored fine particle dispersion shown below was added as a solid content while stirring. While stirring the obtained mixed dispersion, 0.5 part of 0.5 wt% aluminum sulfate aqueous solution was added dropwise as a solid content. Thereafter, while stirring, the temperature was raised to 50 ° C. over 20 minutes and held for 1 hour, and further raised to 51 ° C. over 5 minutes (the above is the aggregation step).

Thereafter, the particle diameter was measured with a Coulter counter. When the volume median diameter became 7.74 μm (about 3 hours after the addition of the ferrous sulfate solution), a 10% neogen SC aqueous solution (10% solid content) was obtained. Part) was heated to 95 ° C. over 35 minutes and held for 2 hours. Thereafter, the toner slurry B was obtained by cooling. The solid content concentration of the toner slurry B was 19.4% by weight, and the particle diameter of the toner slurry B was 7.5 μm as measured with a Coulter counter (the above is the aging step).
<Colored fine particle dispersion>
Pigment Blue 15: 3 aqueous dispersion (manufactured by Dainichi Seika Co., Ltd., “EP-700 Blue GA”, solid content 35%) was used. The volume average particle diameter measured by UPA was 150 nm.

(4) Cleaning and drying of toner particles After filtering the toner slurry B, 800 parts by weight of demineralized water having an electric conductivity of 0.5 μS / cm was added to 100 parts by weight of the toner particles. The mixture was washed with stirring for 60 minutes and filtered (first wash). We went in order. Filtration performed in this order, addition of demineralized water, and stirring and washing were repeated three times to reduce the electrical conductivity of the filtrate to 20 μS / cm. Thereafter, the toner cake obtained by filtration was blown and dried at 40 ° C. for 2 days to obtain toner particles B. The toner particles B were molded into a plate shape and measured with fluorescent X-rays. As a result, the sulfur element content was 0.41% by weight. The PC fog was ΔE = 10, which was a practically unusable level.

[Example 1]
In the production of the toner slurry of Comparative Example 1, the amount used was reduced to 1 part instead of adding 10 parts of 10% Neogen SC aqueous solution as a solid content. Instead of reducing the amount used, the slurry was stirred and held at 60 ° C. for 60 minutes. Thereafter, as in Comparative Example 1, the temperature was raised to 95 ° C. over 35 minutes and held for 2 hours. Thereafter, the toner slurry 1 was obtained by cooling. The solid content concentration of the toner slurry 1 was 19.8% by weight, and the particle diameter of the toner slurry 1 was 7.3 μm as measured by a Coulter counter.

  Thereafter, the operations of filtration of toner particles, addition of demineralized water and stirring and washing were repeated 10 times in the same manner as in Comparative Example 1, and finally drying was performed in the same manner as in Comparative Example 1 to obtain toner particles 1. The electric conductivity of the filtrate obtained in the final washing was 1.2 μS / cm. The toner particles 1 were molded into a plate shape and measured with fluorescent X-rays. As a result, the content of S element was 0.29% by weight. The PC fog was ΔE = 1.2, which was a practical level.

[Example 2]
In the cleaning of the toner particles obtained in Example 1, the washing operation was strengthened by changing the number of times of water washing 10 times to 25 times. As a result, the electrical conductivity of the filtrate obtained by the final washing decreased to 0.9 μs / cm. The obtained toner particles 2 were molded into a plate shape and measured with fluorescent X-rays. As a result, the content of S element was 0.13% by weight. The PC fog was ΔE = 1.0, which was a practical level.

[Example 3]
In the production of the toner slurry of Comparative Example 1, a 5% FeSO ₄ .7H ₂ O aqueous solution was added to 10 ppm instead of adding 100 ppm as an Fe element, and 0.5 part of aluminum sulfate aqueous solution was added dropwise to 0.5 parts as a solid content. The amount used was reduced to 01 parts, and the toner was aggregated under mild conditions. Thereafter, re-dispersion of the agglomerated particles was performed in the same manner as in Comparative Example 1 using a 10% neogen SC aqueous solution to obtain toner slurry 3. The solid content concentration of the toner slurry 3 was 19.5% by weight, and the particle diameter of the toner slurry 3 was 7.4 μm as measured by a Coulter counter. Thereafter, filtration, addition of demineralized water, and stirring and washing were repeated in the same manner as in Example 2. As a result, the electrical conductivity of the filtrate obtained by the final washing decreased to 0.8 μS / cm. The obtained toner particles 3 were molded into a plate shape and measured with fluorescent X-rays. The content of S element was 0.07% by weight. The PC fog was ΔE = 0.5, which was a good level.

Claims (11)

  Aggregation step (1) in which coagulation is caused in a dispersion containing primary particles of a polymer obtained by mixing and dispersing an emulsion polymerization latex and at least a colorant to produce particle aggregates, and the particle aggregates are contained In the toner production method, the aging step (2) for causing fusion between the agglomerated particles in the dispersion liquid and the water washing step (3) for washing the aged particle agglomerate with water are performed. The sulfur content in the toner obtained by performing 1) in the presence of an electrolyte, performing the aging step (2) in the presence of an emulsifier containing a sulfur element, and performing the water washing step (3) multiple times. The method for producing a toner for developing an electrostatic charge image, wherein the toner is 0.3 wt% or less.   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the sulfur content is 0.2% by weight or less.   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the sulfur content is 0.1% by weight or less.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 3, wherein the electrolyte used in the aggregation step (1) is a sulfate.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the emulsifier containing a sulfur element used in the aging step (2) is an alkylbenzene sulfonate.   The amount of the emulsifier containing the sulfur element used in the aging step (2) is 1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the latex solid and the colorant. The method for producing a toner for developing an electrostatic charge image according to any one of the above.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 6, wherein the aging step (2) is carried out in the presence of an alkali.   The aging step (2) is performed at a temperature of 80 ° C. higher than the glass transition temperature or glass transition temperature of the polymer in the latex, and the temperature rise from the aggregation step (1) to the aging step (2) is 0.1. The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 7, wherein the method is carried out in a range of -3 ° C / min.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 8, wherein at least one of the water washing steps (3) performed a plurality of times is performed in the presence of an alkali.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 9, wherein at least one of the water washing steps (3) performed a plurality of times is performed in the presence of an acid.   The electrostatic charge image developing toner according to claim 9 or 10, wherein the toner for electrostatic image development according to claim 9 or 10 is performed under a condition that the electrical conductivity of the final cleaning liquid in the water cleaning step (3) performed a plurality of times is 1.5 µS / cm or less. Production method.