JP4271540B2 - Method for producing toner for developing electrostatic image - Google Patents

Description

  The present invention relates to a method for producing a toner for developing an electrostatic charge image, and more particularly to a method for efficiently producing a toner for developing an electrostatic image having excellent development performance.

  In general, a visible image is formed by electrophotography by first forming an electrostatic latent image on a photosensitive drum, then developing it with toner, transferring it to transfer paper, and fixing it with heat or the like. The As a toner for developing an electrostatic image at that time, usually, a binder resin and a colorant are dry-mixed with a charge control agent, a release agent, a magnetic material, etc., if necessary, and then melt-kneaded with an extruder or the like. Then, for the purpose of imparting various performances such as fluidity to the toner particles obtained by the so-called melt-kneading pulverization method, which is then pulverized and classified, solid fine particles such as silica were adhered to the surface as external additives. The form is used.

  In recent years, image quality should be improved as a performance of copying machines, printers, etc. In order to achieve this, it is necessary that the average particle size of the toner base particles is about 3 to 8 μm and the particle size distribution is narrow. However, in the melt kneading and pulverizing method, it is difficult to control the particle size of the toner base particles, and when trying to obtain toner particles having an average particle size in the range of 3 to 8 μm, it is inevitably less than the desired particle size. There was a problem that a large amount of fine powder was by-produced and it was difficult to separate this in the classification step.

  As a method for improving the above problems in the melt-kneading and pulverizing method, a suspension monomer in which a polymerizable monomer, a polymerization initiator, a colorant and the like are suspended and dispersed in an aqueous medium and then polymerized to produce toner mother particles. A polymer primary particle emulsion obtained by emulsifying a polymerizable monomer in an aqueous medium containing a polymerization method and a polymerization initiator and an emulsifier, and polymerizing the polymerizable monomer under stirring, a colorant and There has been proposed an emulsion polymerization aggregation method or the like in which a charge control agent or the like is added as necessary to aggregate the polymer primary particles, and the obtained aggregated particles are aged to produce toner mother particles. These production methods called polymerization methods make it easy to control the particle size of the toner base particles, so that toner base particles having a small particle size and a narrow particle size distribution and excellent image quality can be obtained.

  On the other hand, with the recent spread of copiers and printers, the demand for image quality has become more and more sophisticated, especially for the purpose of providing toner with excellent high-speed printing and low-energy fixability. Has been done. In order to achieve this, it is necessary to lower the softening point of the toner. However, the toner with a low softening point has a problem of poor blocking resistance and high temperature offset property. In order to improve this, in general, it is necessary to sufficiently attach the same external additive to the toner surface as in the melt-kneading pulverization method. However, in the case of a low softening point toner, in the stage before attaching the external additive. The problem is that toner aggregation and blocking already occur and the particle size becomes coarse. In addition, such a problem is more conspicuous in the emulsion polymerization aggregation method having a relatively low circularity as the polymerization method toner than in the high circularity toner obtained by the suspension polymerization method.

As a method for coating the external additive while suppressing aggregation of the toner, a method for producing a toner in which solid fine particles are added to a wet polymerization toner and dried while mixing has been proposed (for example, Patent Documents). 1).
JP-A-2001-281928.

However, the production method disclosed therein can be applied to a case where an external additive is coated on a toner having a high degree of circularity as obtained by a suspension polymerization method, but can be obtained by an emulsion polymerization aggregation method. It has been found that it is difficult to sufficiently coat the external additive with a toner having a 50% circularity of about 0.90 to 0.98.

  The present invention has been made in view of the above-described prior art. Therefore, the present invention can efficiently coat an external additive on toner base particles obtained by an emulsion polymerization aggregation method, and can perform continuous printing. It is an object of the present invention to provide a method for efficiently producing a toner for developing an electrostatic image excellent in developing performance and fixing performance even in such a case.

As a result of intensive studies to solve the above-mentioned problems, the present invention can achieve the above object by mixing toner mother particles obtained by an emulsion polymerization aggregation method with solid fine particles in a state of a specific water content and drying. The present invention has been completed. That is, the gist of the present invention is a method for producing a toner for developing an electrostatic image comprising a step of drying wet toner base particles produced by an emulsion polymerization aggregation method and an external addition step , the drying step comprising rate from 1 to 35% der is, and includes a step 50% circularity of the toner mother particles is mixed dry and at least one solid particulate toner base particles is 0.90 to 0.98, the particle size 25μm The present invention resides in a method for producing an electrostatic charge image developing toner, wherein the electrostatic charge image development toner having a volume fraction of 1% or less is obtained .

  According to the present invention, it is possible to provide a method for producing a toner for developing an electrostatic image capable of efficiently coating an external additive on toner base particles, and also when charging performance is stable and continuous printing is performed. In addition, it is possible to provide a toner for developing an electrostatic charge image that has little deterioration in developing performance and fixing performance and also has good blocking resistance.

Hereinafter, the method for producing the toner for developing an electrostatic charge image of the present invention will be described in detail.
The toner for developing an electrostatic image by the production method of the present invention contains at least a binder resin and a colorant, and if necessary, solid fine particles are added to the toner base particles containing a wax, a charge control agent and other additives. It is attached.
As the binder resin used in the present invention, various known resins suitable for toners can be used. For example, styrene resin, polyester resin, epoxy resin, polyurethane resin, vinyl chloride resin, polyethylene, polypropylene, ionomer resin, Examples thereof include silicone resin, rosin-modified maleic resin, phenol resin, ketone resin, ethylene-ethyl acrylate copolymer, polyvinyl butyral resin, and the like, and a mixture thereof may be used. A particularly preferred resin for use in the present invention is a styrene resin.

Examples of styrene resins include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene- Vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, Styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-acrylic ester-acrylic acid copolymer (styrene-methyl acrylate-acrylic acid copolymer, styrene-ethyl acrylate- Acrylic acid copolymer, styrene-butyl acrylate Acrylic acid copolymer, styrene-octyl acrylate-acrylic acid copolymer, styrene-phenyl acrylate-acrylic acid copolymer, etc.), styrene-acrylic acid ester-methacrylic acid copolymer (styrene-methyl acrylate- Methacrylic acid copolymer, styrene-ethyl acrylate-methacrylic acid copolymer, styrene-butyl acrylate-methacrylic acid copolymer, styrene-octyl acrylate-methacrylic acid copolymer, styrene-phenyl acrylate-methacrylic acid Copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer). , Styrene-phenyl methacrylate copolymer ), Styrene-methacrylic acid ester-acrylic acid copolymer (styrene-methyl methacrylate-acrylic acid copolymer, styrene-ethyl methacrylate-acrylic acid copolymer, styrene-butyl methacrylate-acrylic acid copolymer) Styrene-octyl methacrylate-acrylic acid copolymer, styrene-phenyl methacrylate-acrylic acid copolymer, etc.), styrene-methacrylic acid ester-methacrylic acid copolymer (styrene-methyl methacrylate-methacrylic acid copolymer) Styrene-ethyl methacrylate-methacrylic acid copolymer, styrene-butyl methacrylate-methacrylic acid copolymer, styrene-octyl methacrylate-methacrylic acid copolymer, styrene-phenyl methacrylate-methacrylic acid copolymer, etc.) , Styrene-α-Chloracryl Methyl methacrylate copolymer and styrene - acrylonitrile - homopolymers or copolymers containing styrene or styrene derivatives such as acrylic acid ester copolymer. These may be a mixture thereof. Among them, styrene-acrylic acid ester-acrylic acid copolymer, styrene-acrylic acid ester-methacrylic acid copolymer, styrene-methacrylic acid ester-acrylic acid copolymer, styrene-methacrylic acid ester-methacrylic acid copolymer. It is more preferable that at least one binder resin having an acid group selected from the above is excellent in terms of fixability and durability when the toner is used, and the charging stability of the toner is improved. In addition, although the ester group in acrylic acid ester or methacrylic acid ester is not limited, methyl ester, ethyl ester, butyl ester, octyl ester, phenyl ester, etc. are mentioned.

  The glass transition temperature (hereinafter abbreviated as Tg) measured by a differential scanning calorimeter (hereinafter abbreviated as DSC) of the binder resin is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, preferably It is desirable that the temperature is 80 ° C. or lower, more preferably 70 ° C. or lower. If Tg exceeds the above range, the low-temperature fixability of the obtained toner may be deteriorated, or the transparency of the toner may not be obtained when a full color toner is used. Further, when Tg is less than the above range, the storage stability of the toner may be deteriorated. In the present invention, Tg is obtained by drawing a tangent line at the start of transition (inflection) of a curve measured with a differential scanning calorimeter (DTA-40 manufactured by Shimadzu Corporation) at a temperature rising rate of 10 ° C./min. It can be determined as the temperature of the intersection of

  The binder resin used in the present invention has at least one of the peak molecular weights in gel permeation chromatography, preferably 3000 or more, more preferably 10,000 or more, still more preferably 30,000 or more, preferably 100,000. In the following, it is desirable to be present at 70,000 or less, more preferably 60,000 or less. When the peak molecular weight is in the above range, it is desirable because the durability, storage stability, and fixability of the toner are improved.

The colorant used in the present invention is not particularly limited, and various inorganic and organic dyes and pigments generally used as a toner colorant are used. Specifically, for example, iron Powder, metal powder such as copper powder, metal oxide such as bengara, inorganic pigment such as carbon represented by carbon black such as furnace black and lamp black, azo type such as benzidine yellow and benzidine orange, quinoline yellow, Acid dyes, basic dyes such as alkali blues, precipitates of rhodamine, magenta, macalite green, etc. dyes such as tannic acid, phosphomolybdic acid, etc. Acid dyes, basic dyes, metal salts of hydroxyanthraquinones Mordant dyes such as phthalocyanine blue, phthalocyanine series such as copper phthalocyanine sulfonate Organic pigments such as quinacridone red and quinacridone violet, organic pigments such as quinacridone and dioxane, aniline black, azo dyes, naphthoquinone dyes, indigo dyes, nigrosine dyes, phthalocyanine dyes, polymethine dyes, di- and triallylmethane dyes, etc. These can be used in combination.

  Colorants used in full-color toners include yellow azo pigments (insoluble monoazo, insoluble disazo, condensed azo, etc.), polycyclic pigments (isoindoline, isoindolinone, slen, quinophthalone, etc.) Azo pigments (azo lakes, insoluble monoazos, insoluble disazos, condensed azos, etc.), polycyclic pigments (quinacridone pigments, perylene pigments, etc.) and the like for magenta Examples include phthalocyanine pigments and selenium pigments. The combination of the colorants may be appropriately selected in consideration of the hue and the like. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. At least one selected from CI Pigment Yellow 155 is C.I. I. Pigment red 238, C.I. I. Pigment red 269, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 48: 2, C.I. I. At least one selected from CI Pigment Red 122 is C.I. I. Pigment blue 15, C.I. I. At least one selected from CI Pigment Blue 15: 3 is preferable as furnace black carbon as the black colorant.

The content of the colorant is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and particularly 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin. Is good. When two or more colorants are used in combination, the total amount is preferably within the above range.
The colorant may have magnetism, and examples of the magnetic colorant include a ferromagnetic material that exhibits ferrimagnetism or ferromagnetism at a temperature around 0 to 60 ° C., which is a use environment temperature of a copying machine or the like. Is, for example, magnetite (Fe ₃ O ₄ ), maghemite (γ-Fe ₂ O ₃ ), an intermediate or mixture of magnetite and maghematite, M _x Fe _{3 -x} O ₄ ; where M is Mg, Spinel ferrite such as Mn, Fe, Co, Ni, Cu, Zn, Cd, hexagonal ferrite such as BaO.6Fe ₂ O ₃ , SrO.6Fe ₂ O ₃ , Y ₃ Fe ₅ O ₁₂ , Sm ₃ Fe ₅ O garnet-type oxides such as _12, rutile-type oxide such as CrO _2, and illustrates Cr, Mn, Fe, Co, the magnetic near 0 to 60 ° C. of such metal or their ferromagnetic alloys such as Ni Among them, Magne Ito, intermediates maghemite or magnetite and maghematite is preferred. When the toner is added from the viewpoint of preventing scattering and charging control while maintaining the characteristics as a non-magnetic toner, the addition amount is 0.5 to 10 parts by weight, preferably 0. 5 to 8 parts by weight, more preferably 1 to 5 parts by weight. Further, when used as a magnetic toner, the addition amount is preferably 20 parts by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the binder resin.

The toner for developing an electrostatic image in the present invention may contain a wax. By containing a wax, the low temperature fixing property, the high temperature offset property, the filming resistance and the like may be improved, which is preferable.
The wax is not limited as long as it is usually used for toner applications, and specifically, olefin wax such as low molecular weight polyethylene, low molecular weight polypropylene, copolymer polyethylene, paraffin wax, silicone wax having an alkyl group; A higher fatty acid such as stearic acid; a long-chain aliphatic alcohol such as eicosanol; an ester wax having a long-chain aliphatic group such as behenyl behenate, a montanic acid ester, and stearyl stearate; a long-chain alkyl group such as distearyl ketone; Ketones, plant waxes such as hydrogenated castor oil carnauba wax; esters or partial esters obtained from polyhydric alcohols such as glycerin and pentaerythritol and long chain fatty acids; higher fatty acid amides such as oleic acid amide and stearic acid amide Low Molecular weight polyesters, and the like. The wax suitable for the present invention can be suitably used by selecting from olefin wax such as ester wax, paraffin wax, low molecular weight polypropylene and copolymer polyethylene, and silicone wax having an alkyl group.

The content of the wax is preferably 0.05 parts by weight or more with respect to 100 parts by weight of the toner, more preferably 0.1 parts by weight or more, and preferably 20 parts by weight or less, more preferably 15 parts by weight or less. It is good to be.
It is preferable that the wax has at least one endothermic peak due to DSC at 50 to 100 ° C.

  The dispersed particle diameter of the wax in the toner for developing an electrostatic charge image in the present invention is preferably 0.1 μm or more, more preferably 0.3 μm or more, preferably 3 μm or less, more preferably 1 μm or less as an average particle diameter. is there. If the average particle size is less than the above range, the effect of improving the releasability of the toner may not be sufficient, and if it exceeds the above range, it may be easily exposed on the surface of the toner and the chargeability and heat resistance may be reduced. The dispersed particle diameter of the wax is not limited to the method in which the toner is thinned and observed with an electron microscope, or the binder resin of the toner is eluted with an organic solvent that does not dissolve the wax and then filtered through a filter. Can be confirmed by a method of measuring with a microscope.

  A charge control agent may be added to the toner for developing an electrostatic image in the present invention in order to impart charge amount and charge stability. As the charge control agent, conventionally known compounds are used. For example, as the positive charge control agent, nigrosine dye, quaternary ammonium salt, triaminotriphenylmethane compound, imidazole compound, polyamine resin, etc. Examples of the negatively chargeable charge control agent include azo complex compound dyes, alkyl salicylic acid complex compounds and curixarene compounds containing atoms such as Cr, Co, Al, Fe, and B. For full-color toners, it is necessary to select a color tone of the charge control agent that is colorless or light in order to avoid a color tone failure as a toner. A quaternary ammonium salt and an imidazole compound are preferable, and the negatively chargeable charge control agent is an alkyl salicylic acid complex compound or a curixarene compound containing atoms such as Cr, Co, Al, Fe, and B. preferable. Moreover, these mixtures may be sufficient. The addition amount of the charge control agent is preferably in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

Further, in the present invention, the toner contains various known internal additives such as silicone oil and silicone varnish for the purpose of modifying the adhesiveness, cohesiveness, fluidity, chargeability, surface resistance, etc. of the toner. You can also
Hereinafter, the method for producing the toner for developing an electrostatic charge image of the present invention will be described in detail.
In the method for producing a toner for developing an electrostatic charge image of the present invention, a toner substantially obtained by an emulsion polymerization aggregation method is used. However, a part of the method is not limited to a suspension polymerization method or solvent precipitation within the range not impairing the effect of the present invention. It may include those obtained by other wet polymerization methods such as a method, and those obtained by a dry method such as a melt-kneading method. In the production method of the present invention, the amount of the toner base particles other than the emulsion polymerization aggregation method is usually 30% by weight or less, preferably 15% by weight or less, more preferably 5% by weight or less, more preferably in all the base particles. It is desirable that is substantially only by the emulsion polymerization aggregation method.

Hereinafter, a method for producing an electrostatic charge image developing toner by an emulsion polymerization aggregation method will be described.
In the case of producing toner mother particles by the emulsion polymerization aggregation method, usually, the emulsion polymerization step, the mixing step, the aggregation step, the aging step, and the washing / drying step are included. That is, generally, a dispersion containing polymer primary particles as a binder resin obtained by emulsion polymerization is mixed with a colorant, if necessary, a charge control agent, wax, etc., and the primary particles in this dispersion are mixed. Is agglomerated and aged to form a particle aggregate having a volume average particle size of about 3 to 8 μm, and the obtained toner base particles are washed and dried.

  As the binder resin constituting the polymer primary particles used in the emulsion polymerization aggregation method, the resin described above is used. As the polymerizable monomer, a monomer having a Bronsted acidic group (hereinafter, sometimes simply referred to as an acidic monomer). ) Or a monomer having a Bronsted basic group (hereinafter sometimes simply referred to as a basic monomer) and a monomer having neither a Bronsted acidic group nor a Bronsted basic group (hereinafter referred to as other monomers) Are preferably used as raw material monomers. At this time, each monomer may be added separately, or a plurality of monomers may be mixed in advance and added simultaneously. Further, the monomer may be added as it is, or may be added as an emulsified liquid previously mixed and adjusted with water or an emulsifier.

  Examples of acidic monomers 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 sulfonamide groups such as vinylbenzenesulfonamide. And the like. The basic monomer has an aromatic vinyl compound having an amino group such as aminostyrene, a nitrogen-containing heterocyclic ring-containing monomer such as vinylpyridine and vinylpyrrolidone, and an amino group such as dimethylaminoethyl acrylate and diethylaminoethyl methacrylate ( And (meth) acrylic acid esters. These acidic monomers and basic monomers may be used alone or in combination, and may exist as a salt with a counter ion. Among these, it is preferable to use an acidic monomer, more preferably acrylic acid and / or methacrylic acid.

The total amount of acidic monomer and basic monomer in 100% by weight of all monomers constituting the binder resin as the polymer primary particles is preferably 0.05% by weight or more, more preferably 0.5% by weight or more, further It is preferably 1% by weight or more, preferably 10% by weight or less, and more preferably 5% by weight or less.
Examples of other monomers include styrenes such as styrene, methylstyrene, chlorostyrene, dichlorostyrene, p-tert-butylstyrene, pn-butylstyrene, and pn-nonylstyrene, methyl acrylate, ethyl acrylate, Acrylic esters such as propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate , Methacrylate esters such as hydroxyethyl methacrylate, ethylhexyl methacrylate, acrylamide, N-propylacrylamide, N, N-dimethylacrylamide, N, N-dipropylacrylamide, N, N Dibutyl acrylamide, acrylic acid amide and the like, monomers may be used alone, or may be used in combination.

  Further, when a crosslinked resin is used as the binder resin constituting the polymer primary particles, a polyfunctional monomer having radical polymerization is used as the crosslinking agent shared with the above-mentioned monomers, for example, divinylbenzene, hexanediol diene. Examples include acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol acrylate, and diallyl phthalate. It is also possible to use a monomer having a reactive group in a pendant group, such as glycidyl methacrylate, methylol acrylamide, acrolein and the like. Among these, radical polymerizable bifunctional monomers are preferable, and divinylbenzene and hexanediol diacrylate are particularly preferable. These polyfunctional monomers may be used alone or in combination.

  When a crosslinked resin is used as the binder resin constituting the polymer primary particles, the blending ratio of the polyfunctional monomer in the total monomers constituting the resin is preferably 0.005% by weight or more, more preferably 0.1%. It is desirable that the content is not less than wt%, more preferably not less than 0.3 wt%, preferably not more than 5 wt%, more preferably not more than 3 wt%, still more preferably not more than 1 wt%.

Known emulsifiers can be used for emulsion polymerization, but one or more emulsifiers selected from cationic surfactants, anionic surfactants and nonionic surfactants are used in combination. be able to.
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 examples of the anionic surfactant include And fatty acid soap such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate and the like. Nonionic surfactants include, for example, polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, monodecanoyl sucrose, etc. Is mentioned.

The amount of the emulsifier is usually 0.1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer, and these emulsifiers include, for example, partially or completely saponified polyvinyl alcohols such as polyvinyl alcohol. One or more of cellulose derivatives such as hydroxyethyl cellulose can be used in combination as a protective colloid.
Examples of the polymerization initiator include hydrogen peroxide; persulfates such as potassium persulfate; organic peroxides such as benzoyl peroxide and lauroyl peroxide; 2,2′-azobisisobutyronitrile; One or two or more azo compounds such as 2′-azobis (2,4-dimethylvaleronitrile) are usually added in an amount of 0.1 to 3 parts by weight with respect to 100 parts by weight of the polymerizable monomer. Used in In addition, these polymerization initiators may be one of reducing agents such as reducing organic compounds such as ascorbic acid, tartaric acid and citric acid, and reducing inorganic compounds such as sodium thiosulfate, sodium bisulfite and sodium metabisulfite. It can also be set as the redox type | system | group initiator which used 2 or more types together. Of these, hydrogen peroxide, organic peroxides, and azo compounds are preferable as the initiator.

In addition, one or two or more suspension stabilizers such as calcium phosphate, magnesium phosphate, calcium hydroxide, and magnesium hydroxide are usually used in an amount of 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer. May be.
Any of the polymerization initiator and the suspension stabilizer may be added to the polymerization system at any time before, at the same time as or after the addition of the monomer, and these addition methods may be combined as necessary. good.

  In the emulsion polymerization, a known chain transfer agent can be used as necessary. Specific examples of such a chain transfer agent include t-dodecyl mercaptan, 2-mercaptoethanol, diisopropyl xanthogen, four Examples thereof include carbon chloride and trichlorobromomethane. The chain transfer agent may be used alone or in combination of two or more, and is usually used in the range of 5% by weight or less based on the total monomers. Further, a pH adjuster, a polymerization degree adjuster, an antifoaming agent, and the like can be appropriately added to the reaction system.

In emulsion polymerization, the above monomers are polymerized in the presence of a polymerization initiator, and the polymerization temperature is usually 50 to 120 ° C, preferably 60 to 100 ° C, and more preferably 70 to 90 ° C.
The volume average particle diameter of the polymer primary particles obtained by emulsion polymerization is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, usually 3 μm or less, preferably 2 μm or less, Preferably, it is 1 μm or less. If the particle size is less than the above range, it may be difficult to control the aggregation rate in the aggregation process. If the particle size exceeds the above range, the particle size of the toner obtained by aggregation tends to be large. It may be difficult to obtain.

  In the production method of the present invention, a resin obtained by a polymerization method different from emulsion polymerization can be used in combination as the polymer primary particles, but the volume average particle size of such a resin is usually 0.02 μm or more. Preferably, it is 0.05 μm or more, more preferably 0.1 μm or more, and usually 3 μm or less, preferably 2 μm or less, more preferably 1 μm or less.

As a blending method of the colorant in the emulsion polymerization aggregation method, the dispersion of the primary polymer particles and the dispersion of the colorant particles are usually mixed to form a mixed dispersion, and then aggregated to form the particle aggregate. To do. The colorant is preferably used in the state of being emulsified in water in the presence of an emulsifier, and the volume average particle diameter of the colorant particles is preferably 0.01 to 3 μm.
As a method of blending the wax in the emulsion polymerization aggregation method, a wax emulsion previously emulsified and dispersed in water at a volume average diameter of 0.01 to 2.0 μm, more preferably 0.01 to 0.5 μm is added during emulsion polymerization, Or it is preferable to add at the aggregation process. In order to disperse the wax with a suitable dispersed particle diameter in the toner, it is preferable to add the wax as a seed during emulsion polymerization. By adding as a seed, the wax is finely and uniformly dispersed in the toner, so that deterioration of the chargeability and heat resistance of the toner can be suppressed.

  In the emulsion polymerization aggregation method, when a charge control agent is included in the toner, the charge control agent is added together with the monomer during emulsion polymerization, or is added in the aggregation step together with the polymer primary particles and the colorant, or the polymer primary It can be blended by a method of adding particles after agglomerating the particles, the colorant and the like to a particle size suitable for a toner. Of these, it is preferable to emulsify and disperse the charge control agent in water using an emulsifier, and add it as a dispersion having a volume average particle size of 0.01 to 3 μm to the aggregation step.

The volume average particle diameter of the polymer primary particles, the colorant dispersed particles, the wax dispersed particles, the charge control agent dispersed particles, etc. in the above dispersion is measured using, for example, Microtrac UPA (Nikkiso Co., Ltd.). Can do.
In the flocculation step in the emulsion polymerization flocculation method, the blended components such as the polymer primary particles, the colorant particles, and, if necessary, the charge control agent and the wax are mixed simultaneously or sequentially. A dispersion, that is, a polymer primary particle dispersion, a colorant particle dispersion, a charge control agent dispersion if necessary, and a wax fine particle dispersion are prepared and mixed to obtain a mixed dispersion. It is preferable from the viewpoint of the uniformity of the composition and the uniformity of the particle diameter.

  The agglomeration treatment usually includes a method of heating, a method of adding an electrolyte, and a method of combining these in a stirring tank. When primary particles are agglomerated under stirring to obtain particle agglomerates that are approximately the size of the toner, the particle size of the particle agglomerates is controlled from the balance between the agglomeration force between the particles and the shearing force due to agitation. However, the cohesive force can be increased by heating or adding an electrolyte.

As an electrolyte when an electrolyte is added and agglomerated, either an organic salt or an inorganic salt may be used. Specifically, NaCl, KCl, LiCl, Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO _{4 are used.} MgCl ₂ , CaCl ₂ , MgSO ₄ , CaSO ₄ , ZnSO ₄ , Al ₂ (SO ₄ ) ₃ , Fe ₂ (S
O ₄ ) ₃ , CH ₃ COONa, C ₆ H ₅ SO ₃ Na and the like. Of these, inorganic salts having a divalent or higher polyvalent metal cation are preferred.

  The amount of the electrolyte added varies depending on the type of electrolyte, the target particle size, etc., but is usually 0.05 to 25 parts by weight, preferably 0.1 to 15 parts per 100 parts by weight of the solid component of the mixed dispersion. Part by weight, more preferably 0.1 to 10 parts by weight. When the addition amount is less than the above range, the progress of the agglutination reaction is slow, and fine particles of 1 μm or less remain after the agglomeration reaction, or the average particle size of the obtained particle aggregate does not reach the target particle size. If the above range is exceeded, rapid aggregation tends to occur, making it difficult to control the particle size, and the resulting aggregated particles may contain problems such as coarse powder and irregular shapes. is there. The aggregation temperature in the case of performing aggregation by adding an electrolyte is preferably 20 to 70 ° C, more preferably 30 to 60 ° C.

The aggregation temperature when aggregation is carried out only by heating without using an electrolyte is usually in the temperature range of Tg-20 ° C to Tg of the polymer primary particles, and in the range of Tg-10 ° C to Tg-5 ° C. Is preferred.
The time required for agglomeration is optimized depending on the shape of the apparatus and the processing scale, but in order to reach the target particle size, the toner particles are usually held at the predetermined temperature for at least 30 minutes. Is desirable. The temperature rise until reaching the predetermined temperature may be raised at a constant rate, or may be raised stepwise.

  In the present invention, toner mother particles may be formed by coating (adhering or fixing) resin fine particles on the surface of the particle aggregate after the above-described aggregation treatment, if necessary. In some cases, the chargeability and heat resistance can be improved by coating the surface of the particle aggregate with resin fine particles. The volume average particle diameter of the resin fine particles is preferably 0.02 to 3 μm, more preferably 0.05 to 1.5 μm. As the resin fine particles, those obtained by polymerizing the same monomers as those used for the polymer primary particles described above can be used, and among them, a crosslinked resin containing a polyfunctional monomer as a raw material is preferable. Further, it is desirable that the resin fine particles do not contain wax.

The resin fine particles are usually used as a dispersion liquid dispersed in a liquid mainly composed of water with an emulsifier. However, when the charge control agent is added after the aggregation treatment, the resin fine particles are charged into the dispersion liquid containing the particle aggregates. It is preferable to add the resin fine particles after adding the control agent.
In the emulsion polymerization aggregation method, in order to increase the stability of the particle aggregate obtained by aggregation, it is preferable to add an aging step for causing fusion between the aggregated particles. The temperature of the aging step is preferably not less than Tg of the binder resin constituting the primary particles, more preferably not less than 5 ° C higher than the Tg, and preferably not more than 80 ° C higher than the Tg, more preferably The temperature is 50 ° C. or higher than Tg. The time required for the aging step varies depending on the shape of the target toner, but after reaching the glass transition temperature of the polymer constituting the primary particles, usually 0.1 to 10 hours, preferably 1 to 6 hours. It is desirable to hold.

In the emulsion polymerization aggregation method, it is preferable to add an emulsifier or raise the pH value of the aggregate liquid after the above aggregation process, preferably before the aging process or during the aging process. As the emulsifier used here, one or more kinds of emulsifiers that can be used when producing the polymer primary particles can be selected and used, and particularly used when the polymer primary particles are produced. It is preferable to use the same emulsifier. The amount of the emulsifier added is not limited, but is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more with respect to 100 parts by weight of the solid component of the mixed dispersion. Moreover, it is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 10 parts by weight or less. After the aggregation process, before the completion of the ripening process, by adding an emulsifier or by increasing the pH value of the flocculation liquid, aggregation of the particle aggregates aggregated in the aggregation process can be suppressed. In some cases, the generation of coarse particles in the toner can be suppressed.

  By such heat treatment, the primary particles in the aggregate are fused and integrated, and the shape of the toner particles as the aggregate is also nearly spherical. The particle aggregate before the aging step is considered to be an aggregate due to electrostatic or physical aggregation of the primary particles, but after the aging step, the polymer primary particles constituting the particle aggregate are fused together. In addition, the shape of the toner particles can be made nearly spherical. According to such a ripening step, by controlling the temperature and time of the ripening step, a cocoon shape in which primary particles are aggregated, a potato type with advanced fusion, a spherical shape with further fusion, etc. Various shapes of toner can be produced according to the purpose.

  In addition, the surface of the particles obtained by the emulsion polymerization aggregation method is further encapsulated by forming an outer layer mainly composed of a polymer with a thickness of preferably 0.01 to 0.5 μm. It can also be toner base particles. The glass transition temperature of the outer layer polymer in the encapsulated toner particles is preferably 45 to 110 ° C., and preferably higher than the glass transition temperature of the polymer constituting the aggregated (aged) particles.

  The toner base particles thus obtained by the emulsion polymerization aggregation method can then undergo a washing step. The liquid used for washing can be carried out only by replacing the water in which the toner is immersed in the final step in the emulsion polymerization aggregation method or the like, but it can also be washed with an acid or alkali solution or aqueous solution, such as nitric acid, It is preferable to use an inorganic acid such as hydrochloric acid or sulfuric acid, or an organic acid such as citric acid. Moreover, it can also wash | clean with warm water or hot water, and these methods can also be used together. Through such a washing step, the suspension stabilizer, the emulsifier, the unreacted residual monomer and the like can be reduced and removed, which is preferable. In the washing step, it is preferable to repeat the operation of dispersing the toner by concentrating the toner to be washed or making it into a wet cake by, for example, filtering or decanting the liquid to be washed, and adding a new washing liquid to the liquid. . The toner after washing is preferably collected in the form of a wet cake in terms of handling in the subsequent drying process.

The volume average particle size of the toner base particles obtained by the emulsion polymerization aggregation method is preferably 3 to 15 μm, more preferably 5 to 10 μm.
The shape of the toner base particles is 50% circularity measured using a flow particle image analyzer FPIA-2000, preferably 0.90 or more, more preferably 0.92 or more, and still more preferably 0.94. It is above, Preferably it is 0.98 or less, More preferably, it is 0.96 or less. When the 50% circularity is less than the above range, the image density may be lowered due to deterioration of charging due to poor adhesion of the external additive, and when it exceeds the above range, the cleaning may be poor.

  The Tg of the toner base particles by DSC method is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, preferably 80 ° C. or lower, more preferably 70 ° C. or lower. When Tg is in the above range, it is desirable because the storage stability and fixing property of the toner are improved. Here, when the Tg of the toner base particles overlaps with a change in heat quantity based on other components, for example, a melting peak of wax, etc., and cannot be clearly determined, the toner is prepared with the other components excluded. It means the Tg at the time.

The method for producing a toner for developing an electrostatic charge image according to the present invention is characterized by a method of adhering solid fine particles as external additives to toner base particles. That is, the toner produced by the emulsion polymerization aggregation method is mixed with at least one kind of solid fine particles in a wet state and dried.
In the present invention, the wet state means that the moisture content is 1% or more, preferably 2% or more, more preferably 5% or more, and 35% or less, preferably 30% or less, more preferably 25% or less. . When the water content is less than the above range, it is not preferable because aggregation of the mother particles or between the solid fine particles occurs, and when it exceeds the above range, it is not preferable because the solid fine particles do not sufficiently adhere to the mother particles. As described above, the toner base particles obtained by the emulsion polymerization aggregation method are dried together with the solid fine particles in a state adjusted to a specific water content, thereby efficiently and sufficiently attaching the solid fine particles to the surface of the toner base particles. be able to. Although this mechanism is not clear, since the toner base particles obtained by the emulsion polymerization aggregation method are not true circles, an appropriate amount of water is present in the concave portions of the base particles and the portions where the convex portions of the base particles are in contact with each other. This is presumably because the surface of the toner base particles can be coated without agglomeration of the solid fine particles by mixing and drying with the solid fine particles in the state.

  In the present invention, the water content means the weight of water relative to the solid weight, and substantially means the weight of water relative to the dry weight of the toner base particles before the drying step. The moisture content can be calculated by filtering water containing toner in a wet state and measuring the evaporation to dry weight of the solid. The term “water” as used herein means a liquid containing water as a main component. The liquid is compatible with water, such as alcohols and other water-soluble organic solvents, the liquid is incompatible with water, and these liquids. It shall also include dissolved material that dissolves.

  The method for adjusting the moisture content before the drying step to the above range is not limited, but it is preferable in terms of handling to adjust the moisture content by collecting it in the final stage of the washing step. If the wet cake is not collected in the washing process or if it is not passed through the washing process, the toner produced by the above wet method is filtered, decanted, heated and evaporated, spontaneous evaporation, reduced pressure evaporation, dehydration press, centrifugal dehydration The water content can be adjusted by the above.

  The solid fine particles as an external additive used in the present invention can be appropriately selected from various inorganic or organic fine particles. Inorganic fine particles include silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, and other carbides, boron nitride, titanium nitride. Various nitrides such as zirconium nitride and silicon nitride, various borides such as zirconium boride, titanium oxide, calcium oxide, magnesium oxide, zinc oxide, zirconium oxide, copper oxide, aluminum oxide, cerium oxide, silica, colloidal silica, etc. Various oxides, various titanate compounds such as calcium titanate, magnesium titanate, strontium titanate, barium titanate, phosphate compounds such as calcium phosphate, sulfides such as molybdenum disulfide, magnesium fluoride, carbon fluoride, etc. Various metal soaps such as fluoride, aluminum stearate, calcium stearate, zinc stearate, magnesium stearate, talc, hydrotalcite, talc, bentonite, various carbon blacks, conductive carbon black, magnetite, ferrite, etc. it can. As the organic fine particles, fine particles such as styrene resin, acrylic resin, epoxy resin, and melamine resin can be used. Further, the solid fine particles are obtained by applying the surface of the inorganic or organic fine particles to a silane coupling agent, a titanate coupling agent, a silicone oil, a modified silicone oil, a silicone varnish, a fluorine silane coupling agent, a fluorine silicone oil, an amino acid. What has been subjected to surface treatment such as hydrophobization by a treating agent such as a coupling agent having a group or a quaternary ammonium base can be used, and two or more kinds of the treating agents can be used in combination.

Among these solid fine particles, silica, titanium oxide, alumina, zinc oxide, various carbon blacks, conductive carbon blacks and the like are preferably used, and hydrophobic silica is particularly preferable.
The solid fine particles may be used in combination of two or more different types, may be used in combination with those that have been surface-treated and those that have not been surface-treated, or those that have been subjected to different surface treatments, A positively chargeable one and a negatively chargeable one can be used in appropriate combination.

  The average primary particle size of the solid fine particles is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and usually 500 nm or less, preferably 100 nm or less, more preferably 50 nm or less. Moreover, the thing of a different particle size in the said particle size range can also be used together. The average particle size of the solid fine particles can be obtained by observation with an electron microscope or can be converted from the specific surface area by the BET method.

  The addition amount of the solid fine particles is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight with respect to 100 parts by weight of the toner base particles. Or less. If the addition amount is less than the above range, when used as an electrostatic image developing toner, fluidity may be deteriorated and toner consumption may be deteriorated. And vitiligo may occur.

  In the present invention, the step of mixing the toner base particles in the wet state produced by the emulsion polymerization aggregation method and the solid fine particles and the step of drying may be performed simultaneously or sequentially, but in terms of work efficiency. It is preferable to carry out simultaneously. In addition, using the same apparatus, it is possible to perform only the mixing step at an initial stage as a step with time and switch only to the drying step from the middle, or to use the mixing step and the drying step together from the middle.

  The mixing step in the present invention is not limited in the apparatus and mixing conditions as long as the wet toner base particles and the solid fine particles can be mixed, and an independent mixing tank for mixing may be provided. Solid fine particles may be added to the aging tank after completion of the aging step, or the solid fine particles may be added to the washing tank in the above-described washing step, and further, the solid fine particles are added to the drying apparatus in the drying step. You may do it.

  Further, the mixing method may be a method of rotating or vibrating a stirring blade or a stirring bar, or a method of rotating or vibrating the mixing tank (container) itself. Furthermore, a method of blowing a gas, an ultrasonic wave, A method of providing a transmitter, a method of natural stirring by heat transfer, or the like may be used. Among these, from the viewpoint of the uniformity of the mixture, mixing by a method such as rotating or vibrating a stirring blade or a stirring bar is preferable. In some cases, the mixing step is preferable because the mixing is accelerated by heating. When heating in the mixing step, the temperature is preferably 30 ° C. or more and Tg or less of the toner base particles.

  The drying step in the present invention is a step of removing water that wets the toner base particles simultaneously with or subsequent to the mixing step. In the mixing step, the toner particles and the solid fine particles exist independently through water, but the solid fine particles adhere to the toner particle surface through the drying step, and the toner particles Fluidity and blocking resistance can be improved.

  The drying step in the present invention is not limited in apparatus and drying conditions as long as it can remove moisture from a mixture of toner base particles and solid fine particles in a wet state, but is dried while being mechanically stirred or / and fluidized. It is preferable to heat and dry. The drying temperature is not limited, but is preferably equal to or lower than the Tg of the toner base particles. Drying at a temperature exceeding Tg may cause toner coarsening and fusion to equipment, which may adversely affect yield and toner performance.

The drying step in the present invention is particularly preferably a method of drying while mechanically mixing under an air stream or under reduced pressure. Examples of the apparatus for drying while mechanically mixing under an air current include Agromaster (Hosokawa Micron) and Spin Flash Dryer (Matsubo). Examples of the apparatus for drying while mechanically mixing under reduced pressure include a filter dryer (Tanabe Wiltech), an SV mixer (Shinko Pantech), and a conical blender dryer (Japan Dryer). The larger the air flow rate (air volume) when drying by air flow is, the better the drying is promoted, but it is preferable to suppress it to such an extent that fine particles are not scattered.

The optimum temperature, air volume, degree of reduced pressure, and the like in the drying process vary depending on the shape, mechanism, size, and the like of the apparatus used in the drying process, and can be appropriately optimized and used.
The water content of the toner particles obtained by the solid particles adhering to the surface of the toner base particles after the drying step is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. When the moisture content of the toner particles after the drying process exceeds the above range, the solid fine particles are not sufficiently adhered to the toner base particles, so that the solid fine particles may aggregate to cause white spots on the printing portion during image formation. is there. The lower limit of the moisture content after drying is not limited, but in terms of production efficiency, it is preferably 0.01% or more, more preferably 0.05% or more, and further preferably 0.1% or more. Here, the moisture content of the toner particles after the drying step substantially means the weight of water with respect to the dry weight of the toner particles to which solid fine particles are attached (including solid fine particles not to be attached).

  The toner particles having a moisture content after drying in the above range have good fluidity and anti-blocking property because the surface of the toner base particles is sufficiently covered with solid fine particles. The toner particles after drying can be heated to Tg or more of the toner base particles, and the adhesive force between the toner base particles and the solid fine particles is improved by heating at a temperature of about Tg to Tg + 20 ° C. There is a case.

  In the method for producing a toner for developing an electrostatic charge image of the present invention, after mixing the toner base particles and solid fine particles and drying steps, a conventionally known external addition step can be used in combination. Examples of such a process include a method using a mixer and a fixing process. Thus, it may be preferable to use another external addition method in combination with the drying step because the adhesion of the solid fine particles to the toner base particles can be improved.

  In addition, when the external addition step is used in combination, new solid fine particles can be further added and mixed. Addition of new solid fine particles as an external additive as described above may be preferable because the fluidity, blocking resistance, charging characteristics and the like of the toner can be further improved. Examples of the external additive that can be used in the external addition step include those similar to the solid fine particles used in the mixing and drying steps.

  In particular, when silica having an average primary particle size different in the mixing / drying step and the external addition step is used, silica is used in the mixing / drying step, and selected from inorganic fine particles and organic fine particles other than silica in the external addition step. Preferably, one or more selected from inorganic fine particles other than silica and organic fine particles are used in the mixing and drying steps, and silica is used in the external addition step. Also in these cases, the silica to be used is preferably hydrophobized.

Examples of the mixer used in the external addition step include a Henschel mixer, a super mixer, a nauter mixer, a V-type mixer, a double cone mixer, and a drum mixer. Among them, a high-speed stirring type such as a Henschel mixer and a super mixer. Are preferred.
The fixing treatment that can be applied as the external addition step is an apparatus that can apply a compressive shear stress (hereinafter referred to as a compression shearing apparatus) or an apparatus that can melt or soften the surface of the toner base particles (hereinafter referred to as a compressive shearing process apparatus) An external addition method using a particle surface melting apparatus). By using such a fixing process in combination with the mixing and drying steps, solid fine particles are firmly attached to the surface of the toner base particles without substantial pulverization of the toner base particles. In some cases, it is possible to produce a toner that is less likely to be fused to a copying machine / printer member even during continuous actual shooting.

  The compression shearing apparatus generally has a narrow gap composed of a head surface and a head surface, a head surface and a wall surface, or a wall surface and a wall surface that move relative to each other while maintaining a gap. By forcibly passing through the gap portion, compressive stress and shear stress are applied to the particle surface without being substantially pulverized. An example of such a device is a mechanofusion device manufactured by Hosokawa Micron. Further, the particle surface melting apparatus is generally configured so as to fix the externally added fine particles by instantaneously heating the mixture of the basic fine particles and the externally added fine particles to a temperature higher than the melting start temperature of the basic fine particles using a hot air stream or the like. The An example of such an apparatus is a surfing system manufactured by Nippon Pneumatic Co., Ltd.

Thus, the electrostatic image developing toner obtained by the production method of the present invention preferably has a volume average particle diameter (Dv) of 3 to 9 μm, more preferably 4 to 8 μm, and still more preferably 5 to 7 μm. If the volume average particle size exceeds the above range, it may not be suitable for high-resolution image formation, and if it is less than the above range, handling as a powder tends to be difficult.
Further, a sharp particle size distribution of the electrostatic charge image developing toner tends to make the chargeability between the solid particles more uniform, and is preferable as the electrostatic charge image developing toner for achieving high image quality and high speed. . Specifically, the value (Dv / Dn) obtained by dividing the volume average particle diameter (Dv) by the number average particle diameter (Dn) is preferably 1.0 to 1.25, more preferably 1.0 to 1. 20, More preferably, it is 1.0 to 1.1, and is preferably close to 1.0. As a method for measuring the particle size of the electrostatic image developing toner, a commercially available particle size measuring device can be used, but a precise particle size distribution measuring device Coulter Counter, Multisizer II (manufactured by Beckman Coulter, Inc.) Can be used.

  The toner for developing an electrostatic charge image obtained by the production method of the present invention has a content of particles having a particle size of 0.6 to 2.12 μm as measured by a flow particle image analyzer, preferably 15 of the total number of toner particles. It is desirable that the number is not more than number%, more preferably not more than 10 number%, and still more preferably not more than 5 number%. This means that the amount of fine powder is less than a certain amount, but when the amount of fine powder is small, the fluidity of the toner is improved and the chargeability tends to be uniform. Although it is most preferable that the fine powder is not present at all, it is difficult in actual production, and equipment for the removal step is required. Therefore, it is usually 0.5% by number or more, preferably 1.0% by number or more. In order to measure the content of fine powder, for example, a flow type particle image analyzer FPIA-2000 (manufactured by Sysmex Corporation) or the like is preferably used.

  Further, the electrostatic image developing toner obtained by the production method of the present invention preferably has a volume fraction with a particle size of 25 μm or more measured by a Coulter counter, preferably 1% or less, more preferably 0.5% or less, still more preferably. Is preferably 0.1% or less, particularly preferably 0.05% or less. This means that the amount of coarse powder is less than a certain amount. However, when the amount of coarse powder is small, the amount of toner consumed during continuous development is small and the image quality tends to be stable. Although it is most preferable that there is no coarse powder having a particle size of 25 μm or more, the actual production is difficult and equipment for the removal process is usually required.

Furthermore, the volume fraction with a particle size of 15 μm or more is preferably 2% or less, more preferably 1% or less, and still more preferably 0.1% or less. Although it is most preferable that there is no coarse powder having a particle size of 15 μm or more, the actual production is difficult and equipment for the removal process is usually required.
The electrostatic image developing toner has a 50% circularity measured by using a flow type particle image analyzer FPIA-2000, preferably 0.90 or more, more preferably 0.92 or more, and still more preferably. 0.94 or more, preferably 0.98 or less, more preferably 0.9
6 or less. When the 50% circularity is less than the above range, charging, consumption, and image quality may be deteriorated due to poor external addition, and when the above range is exceeded, cleaning may be poor.

  In the present invention, at least one of the peak molecular weights in GPC (gel permeation chromatography) of the THF soluble content of the electrostatic image developing toner in the present invention is preferably 30000 or more, more preferably 40000 or more, and even more preferably 50000 or more. Preferably, it is 200000 or less, more preferably 150,000 or less, and still more preferably 100,000 or less. When the peak molecular weight is lower than the above range, the mechanical durability in the non-magnetic one-component development system is difficult, and when the peak molecular weight is higher than the above range, the low-temperature fixability and the fixing strength are deteriorated, and as a full-color toner. Since transparency is also lowered, it is not preferable.

  The toner for developing an electrostatic image obtained by the production method of the present invention is used for a magnetic two-component developer in which magnetic powders such as ferrite and magnetite coexist as a carrier for conveying the toner to an electrostatic latent image portion by magnetic force. Alternatively, it may be used for either a magnetic one-component developer containing such magnetic powder in the toner or a non-magnetic one-component developer that does not use magnetic powder as a developer. In order to exhibit the effect remarkably, it is particularly preferable to use it as a nonmagnetic developer. The toner obtained by the present invention can be suitably used as a toner for a non-magnetic one-component developer that is subjected to a load due to contact with a blade or the like during charging because solid fine particles are firmly attached to the toner base particles. .

The electrostatic image developing toner obtained by the production method of the present invention can be suitably used for any of black toner, color toner, and full color toner.
When used as the magnetic two-component developer, the carrier that is mixed with the toner to form the developer may be a known magnetic substance such as an iron powder-based, ferrite-based, or magnetite-based carrier, or the surface thereof. A resin-coated one or a magnetic resin carrier can be used. As the carrier coating resin, generally known styrene resins, acrylic resins, styrene acrylic copolymer resins, silicone resins, modified silicone resins, fluorine resins, and the like can be used, but are not limited thereto. It is not a thing. The average particle size of the carrier is not particularly limited, but preferably has an average particle size of 10 to 200 μm. These carriers are preferably used in an amount of 5 to 100 parts by weight with respect to 1 part by weight of the toner.

  As described above, according to the method for producing a toner for developing an electrostatic charge image of the present invention, an external additive can be efficiently coated on the toner base particles. Since the adhesion of the external additive on the particle surface is stable, the charging performance of the toner is stable, and even when continuously printed, the development performance and the fixing performance are hardly deteriorated, and the blocking resistance is also good. It has excellent quality.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to 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”. In addition, the live-action test was conducted by the following method.

[Live-action test]
Using a Casio N4 remodeling machine (non-magnetic one-component image forming apparatus whose photoconductor is an organic photoconductor), a continuous live-action test was conducted at a printing rate of 5%. The image density (ID) of the obtained fixed image was measured with an X-rite 938 (C light source), and the charge amount of the toner was measured with a q / m meter (Model 1210HS) manufactured by TREK. Measurements were made at the initial printing stage and at the time of printing 5,000 sheets, respectively.

Further, the number of printable sheets without causing toner dropping (toner leakage due to charging failure) was measured, and the continuous printability was evaluated according to the following criteria.
No dropouts occur at 10,000 sheets: ○
Occurrence of dripping with 6,000-10 thousand sheets: △
Occurrence of dripping with less than 6,000 sheets: ×

(Example 1)
Production of polymer primary particle dispersion A glass reactor equipped with a stirrer, heating / cooling device, concentrating device, and each raw material / auxiliary charging device was charged with 367 parts of deionized water, sodium dodecylbenzenesulfonate (hereinafter, Abbreviated as DBS.) 0.268 parts were charged and heated to 90 ° C. under a nitrogen stream. Then, the following initiator-1 was added, then the following monomers and emulsifier were added over 5 hours, and then initiator-2 was added over 6 hours to carry out emulsion polymerization.

<Monomers>
Styrene 77 parts Butyl acrylate 23 parts Acrylic acid 2.0 parts Trichlorobromomethane 1.2 parts Hexanediol diacrylate 1.3 parts <Emulsifier>
DBS 0.25 parts Deionized water 22 parts <Initiator-1>
8% aqueous hydrogen peroxide solution 0.13 parts 8% aqueous ascorbic acid solution 0.13 parts <Initiator-2>
8% hydrogen peroxide aqueous solution 0.72 parts 8% ascorbic acid aqueous solution 0.72 parts

After completion of the polymerization reaction, the mixture was cooled to obtain a milky white polymer primary particle dispersion. The obtained polymer primary particles had an average particle size of 0.160 μm (measured by UPA manufactured by Microtrac), a weight average molecular weight (Mw) of 100,000, and a peak molecular weight (Mp) of 45,000.
-Production of toner base particles 100 parts of polymer primary particle dispersion (solid content)
Black pigment (MA100: manufactured by Mitsubishi Chemical Corporation) 6.7 parts (solid content)
(MA100 was used as an emulsion manufactured by Nippon Carbite.)
Sodium chloride 1.0% aqueous solution 4.0 parts DBS 0.02 parts Wax (HYTEC E-433N: manufactured by Toho Chemical Co., Ltd.) 5.0 parts Charge control agent (Bontron E-84: manufactured by Orient Chemical Co., Ltd.) 0.1 parts (Solid content)
(Bontron E-84 was used as a 20% aqueous dispersion.)

  Among the above raw materials, other than the charge control agent is mixed, and while stirring, the temperature is raised from 25 ° C. to 50 ° C. at 1 ° C./min. The charge control agent was added after the holding, and after further holding for 30 minutes, 10 parts of DBS was added to complete the aggregation process. Next, the temperature is raised to 72 ° C. and held for 1 hour, the temperature is raised to 80 ° C. and held for 1 hour, the temperature is raised to 90 ° C. and held for 5 hours, and the maturation step is performed. A slurry A was obtained.

The solid content concentration of the toner slurry A is 19.5%, and the volume average particle size measured by a precision particle size distribution measuring device Coulter Counter, Multisizer II (manufactured by Beckman Coulter, hereinafter abbreviated as Coulter Counter) is 7 .1 μm (deviation count 25%), volume fraction of 25 μm or more was 0.01%. Further, the 50% circularity measured by a flow type particle image analyzer FPIA-2000 was 0.96.

-Washing process A filter dryer (made by Tanabe Wiltech Co., Ltd .: TR-25F type, filtration area 0.24 m ² ) with a filter cloth (made of polypropylene, aeration rate 5 cc / cm ² · min) attached to the separation type filter panel at the bottom of the container ) 26.2 parts of slurry A was transferred. Next, the inside of the container is sealed and 1.9 kg.
After pressurizing to / cm ² , the drain cock under the filter plate was opened and filtration was performed under pressure. At this time, the stirring blade in the container was moved above the liquid level, and when the cake surface appeared with the progress of filtration, the stirring blade was pressed against the cake surface while rotating at 5 rpm to push out the water ( Hereinafter, this operation is abbreviated as smoothing).

Next, 30 parts of deionized water and 0.3 part of a 2 wt% aqueous citric acid solution were added to the container, and the cake was reslurried while stirring at 30 rpm. After stirring for 1 hour, pressure filtration and smoothing were performed again. It was. Further, stirring and washing (30 rpm / 15 minutes) was performed with only 30 parts of deionized water, and pressure filtration and smoothing were performed under the same conditions. The water content at this time was 30%. The volume average particle size measured with a Coulter counter is 7.1 μm (variation coefficient 25%), 25 μm.
The above volume fraction was 0.01%. When measured with a flow particle image analyzer FPIA-2000, the 50% circularity was 0.96.

・ Mixing and drying process Colloidal silica (trade name “R972”, manufactured by Nippon Aerogel Co., Ltd.) obtained by pulverizing a cake with a water content of 30% solidified by smoothing while reversing the stirring blade and then hydrophobizing the cake 0.8 parts of a particle diameter of 0.016 μm) was added. Next, warm water is allowed to flow through the jacket of the filter dryer outer periphery and the stirring blade, the internal temperature is adjusted to 43 ° C., and the system is depressurized (600 to 1300 Pa) while being stirred at 30 rpm to dry the toner. did. At this time, a bag filter on the vacuum side (made by Tetron, air flow rate 300cc / cm ² · min)
And a path equipped with a nitrogen gas ejection valve to prevent the dry toner from scattering to the vacuum side, and to irradiate the toner scattered in the container by pulsing nitrogen gas into the filter at regular intervals. After 10 hours of heating and vacuum drying, the temperature was lowered and the pressure was restored with dry nitrogen. Then, the discharge port on the side of the can was opened, and the stirring blade was rotated to take out the toner from the discharge port. At this time, the recovery rate with respect to the charged solid content was 94%, and the water content of the toner was 0.5%.

External addition process Hydrophobized silica on dried toner (Wacker-Chemie HmbH,
0.1 parts of a trade name “Wacker HDK H30TD” (average particle size 0.008 μm) was added and mixed with a Henschel mixer to obtain an electrostatic image developing toner.

The obtained electrostatic charge image developing toner has a volume average particle diameter measured by a Coulter counter of 7.1 μm (coefficient of variation 25%), a volume fraction of 25 μm or more is 0.03%, and a volume fraction of 15 μm or more is 0. 0.08%, 50% circularity measured by FPIA-2000 was 0.95, which was almost the same particle size, particle size distribution and shape as before the cleaning treatment.
When the actual image was tested using the obtained toner for developing an electrostatic image, the initial ID was 1.6, the charge amount was −15.8 μC / g, the ID after printing 5,000 sheets was 1.5, and the charge was The amount was -14.5 μC / g, and stable characteristics and good image quality were formed even after 10,000 sheets.

(Example 2)
When obtaining a polymer primary particle dispersion, 12 parts of a wax emulsion (obtained by emulsifying 30% ester wax (Unistar M-2222SL, manufactured by NOF Corporation) in the presence of DBS in a high shear state) are seeded in advance. The toner slurry was prepared in the same manner as in Example 1, except that the polymer primary particle dispersion containing wax was encapsulated and the wax used in Example 1 was not used in the aggregation process. B was produced.

The solid content concentration of the toner slurry B is 19.3%, the volume average particle diameter measured in the same manner as in Example 1 is 7.2 μm (deviation count 22%), the volume fraction of 25 μm or more is 0.01%, 50%
The circularity was 0.95.
The washing step, mixing, drying step and external addition step were performed in the same manner as in Example 1 except that the toner slurry B was used and 0.9 parts of colloidal silica “R972” added in the mixing and drying step was used. The water content after the washing step was 28%, the water content after the drying step was 0.8%, and the recovery rate was 93%.

The obtained toner for developing an electrostatic charge image was measured in the same manner as in Example 1. The volume average particle diameter was 7.2 μm (coefficient of variation 25%), the volume fraction above 25 μm was 0.01%, and the volume fraction above 15 μm. The rate was 0.05%, and the 50% circularity was 0.96, which was almost the same particle size, particle size distribution, and shape as before the cleaning treatment.
When the actual image was tested using the obtained toner for developing an electrostatic image, the initial ID was 1.6, the charge amount was −15.5 μC / g, the ID after printing 5,000 sheets was 1.5, and charging The amount was -14.2 μC / g, and stable characteristics and good image quality were formed even after 10,000 sheets.

(Example 3)
In the mixing and drying process of Example 1, 0.8 part of silica “R972” was added and stirred for 1 hour, and further 0.1 part of “Wacker HDK H30TD” was added, and the temperature was adjusted and decompression was started. An electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the external addition step was not performed. The water content after the drying step was 0.3%, and the recovery rate was 94%.

The obtained toner for developing an electrostatic charge image was measured in the same manner as in Example 1. The volume average particle diameter was 7.4 μm (coefficient of variation 24%), the volume fraction above 25 μm was 0.01%, and the volume fraction above 15 μm. The rate was 0.04%, and the 50% circularity was 0.95.
When the actual image was tested using the obtained toner for developing an electrostatic image, the initial ID was 1.5, the charge amount was −16.0 μC / g, the ID after printing 5,000 sheets was 1.4, the charge The amount was −14.0 μC / g, and stable characteristics and good image quality were formed even after 10,000 sheets.

(Comparative Example 1)
Except that silica “R972” was not added in the mixing and drying process of Example 1, and that 0.8 part of silica “R972” and 0.1 part of “Wacker HDK H30TD” were added in two stages in the external addition process. In the same manner as in Example 1, a toner for developing an electrostatic image was obtained. The water content after the drying step was 0.3%, and the recovery rate was 85%.

The obtained toner for developing an electrostatic charge image was measured in the same manner as in Example 1. The volume average particle diameter was 7.4 μm (deviation count 29%), the volume fraction above 25 μm was 3.0%, and the volume fraction above 15 μm. The rate was 4.0%, and the 50% circularity was 0.94.
When the actual image was tested using the obtained toner for developing an electrostatic image, the initial ID was 1.5, the charge amount was -13.0 μC / g, the ID after printing 5,000 sheets was 1.2, and the charge The amount was −9.6 μC / g, and the change in ID and charge amount was large. After printing 5,000 sheets, the image quality deteriorated and the toner dropped.

(Comparative Example 2)
In the drying process of Example 1, an electrostatic charge image developing toner was obtained in the same manner as in Example 1 except that the moisture content before drying was 40%. The water content after the drying step was 0.3%, and the recovery rate was 89%.
The obtained toner for developing an electrostatic charge image was measured in the same manner as in Example 1. The volume average particle size was 7.4 μm (deviation count 27%), the volume fraction above 25 μm was 1.5%, and the volume fraction above 15 μm. The rate was 1.8% and the 50% circularity was 0.95.
Using the obtained toner for developing an electrostatic image, a live-action test was performed. As a result, the initial ID was 1.5, the charge amount was −15.1 μC / g, the ID after printing 5,000 sheets was 1.3, and the charge was The amount was −11.8 μC / g, and the change in ID and charge amount was large. After printing 6,000 sheets, the image quality deteriorated and the toner dropped.

The toner for developing an electrostatic image obtained by the production method of the present invention has a stable charging performance, and even when continuously printed, the development performance and the fixing performance are hardly deteriorated and the blocking resistance is also good. It can be suitably used as a developer for a small copying machine or a printer for printing or printing a large number of sheets.

Claims (5)

A process and external addition step manufacturing method of the electrostatic image developing toner consisting of drying the toner mother particles generated wetted by the emulsion polymerization aggregation method, the drying step, Ri moisture content 1-35% der And a step of mixing and drying toner base particles whose toner base particles have a 50% circularity of 0.90 to 0.98 and at least one kind of solid fine particles, and a volume fraction with a particle size of 25 μm or more is 1% A method for producing an electrostatic charge image developing toner, comprising: obtaining an electrostatic charge image developing toner as described below .   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the toner is dried while stirring or / and flowing.   3. The method for producing a toner for developing an electrostatic charge image according to claim 1, further comprising mixing at least one kind of solid fine particles after the drying step. The toner mother particles are moisture content 5-30%, water content 0.01% or more, toner according to any one of claims 1 to 3, characterized in that drying to less than 5% Manufacturing method. Method for producing a toner according to any one of claims 1 to 4, wherein the solid particulate is silica.