JP2014048525A - Manufacturing method for electrostatic latent development toner, and electrostatic latent development toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent development toner excellent in fixability and storage stability, and to provide a manufacturing method for the same.SOLUTION: An electrostatic latent image development toner comprises toner core particles containing at least, a binding resin, a coloring agent, and a releasing agent, and a shell layer covering the entire surface of the toner core particle. The external surface of the shell layer is smooth. When a cross-section of the electrostatic latent image development toner is observed by a transmission type electronic microscope, a clear boundary is observed between the toner core particles and shell layer. Also, in the shell layer, any substantially vertical crack are not observed on the surface of the toner core particle.

Description

  The present invention relates to an electrostatic latent image developing toner manufacturing method and an electrostatic latent image developing toner.

  In general, in electrophotography, the surface of a photosensitive drum is charged by corona discharge or the like and then exposed by a laser or the like to form an electrostatic latent image. The formed electrostatic latent image is developed with toner to form a toner image. Further, the formed toner image is transferred to a recording medium, and a high quality image is obtained. In general, a toner used for forming a toner image is obtained by mixing components such as a colorant, a charge control agent, and a release agent with a binder resin such as a thermoplastic resin, and then kneading, pulverizing, and classifying steps. Toner particles (toner base particles) having an average particle diameter of 5 μm or more and 10 μm or less are used. For the purpose of imparting fluidity to the toner, imparting suitable charging performance to the toner, and improving the cleaning property of the toner from the photosensitive drum, an inorganic fine powder such as silica or titanium oxide is used. Externally added to the base particles.

  For such toner, a toner core using a low-melting-point binder resin for the purpose of obtaining good fixability at a wide range of temperatures in the low temperature range, for the purpose of improving storage stability at high temperatures, and for improving the blocking resistance. A capsule toner is used in which the particles are coated with a resin having a Tg higher than the glass transition point (Tg) of the binder resin of the toner core particles.

  As such a capsule toner, mixed fine particles composed of release agent fine particles and resin fine particles are attached to the surface of the toner core particles, and the obtained fine particle-attached toner core particles are allowed to flow in an air stream while spraying ethanol. A capsule toner (Patent Document 1) in which a resin coating layer is formed on the surface of toner core particles has been proposed.

JP 2011-81344 A

  However, the capsule toner described in Patent Document 1 is difficult to uniformly coat the surface of the toner core particle with the resin film layer due to aggregation of the fine particles when the fine particles are adhered to the surface of the toner core particle. Therefore, in the capsule toner described in Patent Document 1, a portion where the toner core particle surface is exposed tends to remain. For this reason, even if the capsule toner described in Patent Document 1 is excellent in fixability, when stored at a high temperature, the release agent tends to exude to the toner surface due to the influence of heat and water vapor. Particles tend to aggregate.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a toner for developing an electrostatic latent image having good fixability and storage stability, and a method for producing the same.

  The present inventors have disclosed a shell for developing an electrostatic latent image comprising toner core particles containing at least a binder resin, a colorant, and a release agent, and a shell layer covering the entire surface of the toner core particles. The inventors have found that the above-mentioned problems can be solved by making the layer a specific shape and setting the glass transition point (Tg) of the binder resin and the thickness of the shell layer within a predetermined range, and the present invention has been completed. Specifically, the present invention provides the following.

The first aspect of the present invention is:
Toner core particles containing at least a binder resin, a colorant, and a release agent;
An electrostatic latent image developing toner comprising a shell layer covering the entire surface of the toner core particles,
The initial shell layer is formed using spherical resin fine particles,
When the surface of the toner for developing an electrostatic latent image is observed using a scanning electron microscope, a structure derived from the spherical resin fine particles in the shell layer is observed for toner particles having a particle diameter of 6 μm or more and 8 μm or less. not,
When the cross section of the electrostatic latent image developing toner is observed using a transmission electron microscope, a clear boundary surface is observed between the toner core particles and the shell layer, and the inside of the shell layer is observed. In addition, cracks in a direction substantially perpendicular to the surface of the toner core particles are not observed,
The present invention relates to a toner for developing an electrostatic latent image.

The second aspect of the present invention is:
The present invention relates to a method for producing a toner for developing an electrostatic latent image according to a first aspect, comprising the following steps 1) and 2).
1) a step of dispersing toner core particles containing at least a binder resin, a colorant, and a release agent in an air flow having a flow rate of 30 m / s or more;
2) A step of spraying an aqueous emulsion containing resin fine particles in an air stream in which the toner core particles are dispersed.

  According to the present invention, it is possible to provide a toner for developing an electrostatic latent image having good fixability and storage stability, and a method for producing the same.

FIG. 3 is a cross-sectional view schematically showing an example of the electrostatic latent image developing toner of the present invention. FIG. 3 is a front view showing a configuration of a surface modification device used for manufacturing the electrostatic latent image developing toner of the present invention. It is a schematic sectional drawing of the surface modification apparatus used for manufacture of the toner for electrostatic latent image development of this invention. FIG. 3 is a side view showing a configuration of a powder charging unit and a powder recovery unit included in a surface modifying apparatus used for manufacturing the electrostatic latent image developing toner of the present invention. 4 is a transmission electron micrograph of a cross section of the toner of Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  Hereinafter, the electrostatic latent image developing toner and the manufacturing method of the electrostatic latent image developing toner will be described in order.

[Electrostatic latent image developing toner]
The electrostatic latent image developing toner of the present invention (hereinafter also simply referred to as toner) has a shell layer that covers the entire surface of the toner core particles including at least a binder resin, a colorant, and a release agent. Further, the toner core particles may contain components such as a charge control agent and magnetic powder, if desired. Furthermore, the toner for developing an electrostatic latent image of the present invention can be mixed with a desired carrier and used as a two-component developer.

  The covering state of the surface of the electrostatic latent image developing toner by the shell layer can be confirmed by a scanning electron microscope (SEM). The structure of the shell layer of the electrostatic latent image developing toner can be confirmed by observing the cross section of the toner with a transmission electron microscope (TEM). FIG. 1 shows a schematic diagram of a cross section of the toner for developing an electrostatic latent image of the present invention observed by a TEM.

  As shown in FIG. 1, in the electrostatic latent image developing toner 101, the shell layer 103 is formed on the entire surface of the toner core particles 102, and the outer surface of the shell layer 103 is smooth. In the electrostatic latent image developing toner 101, a clear boundary surface 104 is formed between the toner core particles 102 and the shell layer 103. Furthermore, no cracks in the direction substantially perpendicular to the surface of the toner core particles 102 are observed in the shell layer 103. Therefore, peeling of the shell layer 103 and exudation of the components contained in the toner such as a release agent to the surface of the toner 101 are difficult to occur when the toner 101 is stored at a high temperature.

  The thickness of the shell layer formed on the entire surface of the toner core particle 102 is preferably 30 nm or more and 300 nm. By setting the shell layer in such a range, it is easy to obtain a toner having good fixability and storage stability. In addition, when a shell layer has a convex part, the thickness of a shell layer may be non-uniform | heterogenous. In the case where the thickness of the shell layer is not uniform as described above, the thickness of the thickest portion of the shell layer is defined as “the thickness of the shell layer” in the claims and the specification of the present application.

  On the other hand, when the thickness of the shell layer is too small, the shell layer of the toner may be easily broken due to the stress received inside the developing unit of the image forming apparatus. For this reason, depending on the physical properties such as the binder resin and the release agent (when the glass transition point is too low, etc.), the toner may be fused together or the storage stability may be reduced. In some cases, the toners are partially fused when stored in a warehouse. On the other hand, if the thickness of the shell layer is excessive, it may be difficult to obtain good toner fixability.

  The thickness of the shell layer can be measured by photographing a cross section of the electrostatic latent image developing toner with a TEM. Specifically, the thickness of the coating layer can be measured by analyzing a TEM image of the toner cross section with commercially available image analysis software. WinROOF (manufactured by Mitani Corporation) can be used as commercially available image analysis software.

  The degree of smoothing of the shell layer is determined on the outer surface of the shell layer of toner particles having a particle diameter of 6 μm or more and 8 μm or less when the surface of the toner used in the image forming method of the present invention is observed using a scanning electron microscope. As long as the structure derived from the spherical resin fine particles used for forming the shell layer is not observed. If the state of the shell layer of the toner having a particle diameter of 6 μm or more and 8 μm or less is such a state, the shell layer is formed so that the surface of the core particle is not exposed in most of the toner particles contained in the toner. When the state of the outer surface of the shell layer is confirmed using observation with a scanning electron microscope, the particle diameter of the toner particles is an equivalent circle diameter calculated from the projected area of the toner on the electron microscope image.

  The electrostatic latent image developing toner of the present invention includes toner core particles containing a release agent. However, in the electrostatic latent image developing toner of the present invention, the entire surface of the toner core particles is covered with the shell layer. Further, in the toner for developing an electrostatic latent image according to the present invention, since a clear interface exists between the toner core particles and the shell layer, it is difficult for the release agent to transfer from the toner core particles to the shell layer. Furthermore, in the electrostatic latent developing toner of the present invention, there are no minute voids (cracks) inside the shell layer.

  Due to the above factors, in the toner for developing an electrostatic latent image according to the present invention, when the toner is stored, the release of the release agent from the toner core particles to the toner surface hardly occurs. For this reason, the toner for developing an electrostatic latent image of the present invention can achieve both good fixability and storage stability.

  The essential components and optional components contained in the electrostatic latent image developing toner will be described in the order of binder resin, colorant, release agent, charge control agent, magnetic powder, shell layer material, and carrier.

[Binder resin]
The toner core particles in the toner for developing an electrostatic latent image of the present invention contain a binder resin. The binder resin contained in the toner core particles is not particularly limited as long as it is a resin conventionally used as a binder resin for toner. Specific examples of the binder resin include styrene resin, acrylic resin, styrene acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin. Examples thereof include thermoplastic resins such as resins, vinyl ether resins, N-vinyl resins, and styrene-butadiene resins. Among these resins, styrene acrylic resins and polyester resins are preferable from the viewpoints of dispersibility of the colorant in the toner, chargeability of the toner, and fixability to paper. Hereinafter, the styrene acrylic resin and the polyester resin will be described.

  The styrene acrylic resin is a copolymer of a styrene monomer and an acrylic monomer. Specific examples of the styrene monomer include substances such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and p-ethylstyrene. Can be mentioned. Specific examples of the acrylic monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, meta Examples include (meth) acrylic acid alkyl esters such as methyl acrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate.

  As the polyester-based resin, those obtained by condensation polymerization or co-condensation polymerization of a divalent or trivalent or higher alcohol component and a divalent or trivalent or higher carboxylic acid component can be used. The components used when synthesizing the polyester resin include the following alcohol components and carboxylic acid components.

  Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sol Tan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2, Examples include trivalent or higher alcohols such as 4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Divalent carboxylic acids such as acids, isododecyl succinic acid, alkyl such as isododecenyl succinic acid or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5- Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4 Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid , A trivalent or higher carboxylic acid such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. These divalent or trivalent or higher carboxylic acid components may be used as ester-forming derivatives such as acid halides, acid anhydrides, and lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  When the binder resin is a polyester resin, the softening point of the polyester resin is preferably 80 ° C. or higher and 150 ° C. or lower, and more preferably 90 ° C. or higher and 140 ° C. or lower.

  As the binder resin, it is preferable to use a thermoplastic resin because it has good fixability. However, not only the thermoplastic resin alone but also a crosslinking agent or a thermosetting resin should be added to the thermoplastic resin. Can do. By introducing a partially crosslinked structure into the binder resin, it is possible to improve the storage stability, form retention, and durability of the toner without deteriorating the fixability.

  As the thermosetting resin that can be used together with the thermoplastic resin, for example, an epoxy resin or a cyanate resin is preferable. Specific examples of suitable thermosetting resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins, and cyanate resins. . These thermosetting resins can be used in combination of two or more.

  The glass transition point (Tg) of the binder resin is preferably 45 ° C. or higher and 65 ° C. or lower, and more preferably 50 ° C. or higher and 60 ° C. or lower. When the glass transition point is too high, the low-temperature fixability of the toner tends to decrease.

  The glass transition point of the binder resin can be obtained from the change point of specific heat using a differential scanning calorimeter (DSC). More specifically, it can be determined by measuring an endothermic curve using a differential scanning calorimeter DSC-6200 manufactured by Seiko Instruments Inc. as a measuring device. It was obtained by putting 10 mg of a measurement sample in an aluminum pan, using an empty aluminum pan as a reference, and measuring at a measurement temperature range of 25 ° C. to 200 ° C. and a temperature increase rate of 10 ° C./min. The glass transition point can be determined from the endothermic curve.

  The mass average molecular weight (Mw) of the binder resin is not particularly limited as long as the object of the present invention is not impaired. Typically, the weight average molecular weight is preferably 30,000 or more and 60,000 or less. The mass average molecular weight (Mw) of the binder resin can be measured by gel permeation chromatography according to a conventionally known method.

[Colorant]
The toner core particles in the toner for developing an electrostatic latent image of the present invention contain a colorant. As the colorant contained in the toner core particles, a known pigment or dye can be used according to the color of the toner. Specific examples of suitable colorants to be added to the toner include black pigments such as carbon black, acetylene black, lamp black and aniline black; yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium Yellow, navelous yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, yellow pigments; Orange pigments such as Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Indanthrene Brilliant Orange GK; Bengala, Cadmium Red, Lead Red, Mercury Cadmium Sulfide, Permanent Red Red pigments such as 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B; Manganese Purple, Fast Violet B, Methyl Violet Purple pigments such as lakes; blue pigments such as bitumen, cobalt blue, alkali blue lakes, Victoria blue partial chlorinated products, first sky blue, indanthrene blue BC; chrome green, chromium oxide, pigment green B, malachite green lake, Green pigments such as final yellow green G; white pigments such as zinc white, titanium oxide, antimony white, zinc sulfide; barite powder, barium carbonate, clay, silica, white carbon , Talc, extender pigments such as alumina white. These colorants can be used in combination of two or more for the purpose of adjusting the toner to a desired hue.

  The amount of the colorant used is not particularly limited as long as the object of the present invention is not impaired. Specifically, it is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 17% by mass or less with respect to the total mass of the toner.

〔Release agent〕
The toner core particles of the toner for developing an electrostatic latent image of the present invention contain a release agent for the purpose of improving the toner fixing property and offset resistance. The type of the release agent contained in the toner core particles is not particularly limited as long as the object of the present invention is not impaired. The release agent is preferably a wax, and examples of the wax include substances such as polyethylene wax, polypropylene wax, fluororesin-based wax, Fischer-Tropsch wax, paraffin wax, ester wax, montan wax, and rice wax. These release agents can be used in combination of two or more. By adding such a release agent to the toner, it is possible to more efficiently suppress the occurrence of offset and image smearing (dirt around the image when the image is rubbed).

  The amount of the release agent used is not particularly limited as long as the object of the present invention is not impaired. Specifically, the amount of the release agent used is preferably 1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less with respect to the total mass of the toner. If the amount of the release agent used is too small, the desired effect may not be obtained in terms of suppressing the occurrence of offset and image smearing in the formed image. If the amount of release agent used is excessive, In some cases, the storage stability of the toner may be reduced due to the fusing.

(Charge control agent)
The charge control agent is used for the purpose of obtaining a toner having excellent durability and stability by improving a charge level and a charge rising characteristic that is an index as to whether or not charging is possible in a short time to a predetermined charge level. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used. The charge control agent is preferably blended in the shell layer.

  The type of the charge control agent is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline and quinoxaline; Azin Fast Red FC, Azin Fast Red 12BK, Azine Violet BO, Azine Direct dyes consisting of azine compounds such as Ng Brown 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW, and Azin Deep Black 3RL; Nigrosine such as Nigrosine, Nigrosine Salt, Nigrosine Derivative Compounds; Acid dyes comprising nigrosine compounds such as nigrosine BK, nigrosine NB, nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; A class ammonium salt is mentioned. Among these positively chargeable charge control agents, a nigrosine compound is particularly preferable in that a more rapid start-up property can be obtained. These positively chargeable charge control agents can be used in combination of two or more.

  Quaternary ammonium salts, carboxylates, or resins having a carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene-acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, a carboxylic acid Styrene resin having salt, acrylic resin having carboxylate, styrene-acrylic resin having carboxylate, polyester resin having carboxylate, styrene resin having carboxyl group, acrylic having carboxyl group 1 type or 2 or more types, such as resin, the styrene acrylic resin which has a carboxyl group, and the polyester-type resin which has a carboxyl group, are mentioned. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among resins that can be used as a positively chargeable charge control agent, a styrene-acrylic copolymer having a quaternary ammonium salt as a functional group from the viewpoint that the charge amount can be easily adjusted to a value within a desired range. A resin is more preferable. Specific examples of preferable acrylic comonomers to be copolymerized with styrene units in a styrene-acrylic copolymer resin having a quaternary ammonium salt as a functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic acid. such as iso-propyl, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate (meth ) Acrylic acid alkyl ester.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkyl (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, Specific examples of dialkyl (meth) acrylamide include dimethylmethacrylamide, and specific examples of dialkylaminoalkyl (meth) acrylamide include dimethylaminopropyl methacrylamide. Further, a hydroxy group-containing polymerizable monomer such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, or N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes such as chromium 3,5-di-tert-butylsalicylate. A salicylic acid metal salt is preferable, and a salicylic acid metal complex or a salicylic acid metal salt is more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The amount of the positively or negatively chargeable charge control agent used is not particularly limited as long as the object of the present invention is not impaired. The use amount of the positively or negatively chargeable charge control agent is typically 1.5 parts by mass or more and 15 parts by mass or less, preferably 2.0 parts by mass when the total amount of the toner is 100 parts by mass. The amount is more preferably 8.0 parts by mass or less, and particularly preferably 3.0 parts by mass or more and 7.0 parts by mass or less. When the amount of the charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, so that the image density is lowered and the maintainability of the image density is liable to be lowered (maintaining the image density over a long period of time). It becomes difficult). Further, in such a case, the charge control agent is difficult to uniformly disperse in the toner, and fogging and contamination of the latent image carrier are likely to occur. When the amount of the charge control agent used is excessive, charging failure under high temperature and high humidity due to deterioration of environmental resistance, image failure, and contamination of the latent image carrier are liable to occur.

[Magnetic powder]
The electrostatic latent image developing toner of the present invention can be made into a magnetic one-component developer by blending magnetic powder in a binder resin with toner core particles if desired. The type of magnetic powder used when the toner is a magnetic one-component developer is not particularly limited as long as the object of the present invention is not impaired. Examples of suitable magnetic powders include irons such as ferrite and magnetite; ferromagnetic metals such as cobalt and nickel; alloys containing iron and / or ferromagnetic metals; compounds containing iron and / or ferromagnetic metals A ferromagnetic alloy subjected to a ferromagnetization treatment such as heat treatment; chromium dioxide.

  The particle size of the magnetic powder is not limited as long as the object of the present invention is not impaired. The particle diameter of the specific magnetic powder is preferably 0.1 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When magnetic powder having a particle diameter in such a range is used, it is easy to uniformly disperse the magnetic powder in the binder resin.

  As the magnetic powder, a powder that has been surface-treated with a surface treatment agent such as a titanium-based coupling agent or a silane-based coupling agent can be used for the purpose of improving dispersibility in the binder resin.

  The usage-amount of magnetic powder is not specifically limited in the range which does not inhibit the objective of this invention. The specific amount of magnetic powder used is preferably 35 parts by weight or more and 60 parts by weight or less, and more preferably 40 parts by weight or more and 60 parts by weight or less, when the total amount of toner is 100 parts by weight. If the amount of magnetic powder used is excessive, the durability of the image density may be reduced or the fixability may be extremely reduced. If the amount of magnetic powder used is too low, fog is likely to occur. As a result, the durability of the image density may be lowered.

[Material of shell layer]
The material of the shell layer in the toner for developing an electrostatic latent image of the present invention is not particularly limited as long as the material can coat the toner core particles so that the shell layer has the specific shape described above. As the material of the shell layer, a resin material is usually used. Suitable resin materials for the shell layer include acrylic resin and styrene acrylic resin.

  The method of forming the shell layer is not particularly limited, but the resin fine particles attached to the surface of the toner core particles are removed so that the interface between the resin fine particles disappears by attaching the resin fine particles to the surface of the toner core particles and deforming the resin fine particles. Are preferably united. In addition, it is preferable that the shell layer is formed so that the interface of the resin fine particles completely disappears in the shell layer. A slight interface may remain. Depending on the degree of deformation of the resin fine particles when forming the shell layer, a slight interface between the resin fine particles may remain near the boundary surface between the toner core particles and the shell layer. The storage stability of the toner for developing an electrostatic latent image is not significantly impaired.

  When the shell layer is formed using resin fine particles, the resin fine particles are made of a resin obtained by addition polymerization of a monomer having an unsaturated bond because the resin fine particles having a uniform particle diameter can be easily prepared. It is preferable to use resin fine particles.

  Hereinafter, resin fine particles made of a resin obtained by addition polymerization of a monomer having an unsaturated bond will be described. The type of monomer having an unsaturated bond is not particularly limited as long as the addition polymerization can be performed according to a conventional method, as long as the object of the present invention is not impaired. Specific examples of suitable monomers include vinyls such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, divinylbenzene. Aromatic compounds; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, β- (Meth) acrylic acid derivatives such as ethyl hydroxyacrylate, β-hydroxyethyl methacrylate, γ-hydroxyacrylate, butyl δ-hydroxyacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate; vinyl formate, vinyl acetate, Propio Vinyl esters such as vinyl acid; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether; ethylene, propylene, isobutylene butene-1, pentene-1, 4-methyl Examples include olefins such as pentene-1, butadiene, isoprene and chloroprene.

  The addition polymerization method of the monomer having an unsaturated bond is not limited as long as the object of the present invention is not impaired, and any method such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization can be selected. Among these production methods, the emulsion polymerization method is preferable because resin fine particles having a uniform particle diameter can be easily obtained.

  Polymerization initiators that can be used for addition polymerization of monomers having an unsaturated bond include potassium persulfate, acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, azobisisobutyronitrile, and 2,2′-azobis. Known polymerization initiators such as -2,4-dimethylvaleronitrile and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile can be used. The amount of these polymerization initiators used is preferably 0.1% by mass or more and 15% by mass or less based on the total amount of monomers.

  When the resin fine particles are produced by an emulsion polymerization method, the reaction solution may be emulsified using a surfactant. In emulsion polymerization, at least one selected from the group consisting of a cationic surfactant, an anionic surfactant, and a nonionic surfactant can be used.

  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. Specific examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, and sulfonates such as sodium dodecyl sulfate and sodium dodecylbenzene sulfonate. Specific examples of the nonionic surfactant include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl sucrose.

  The average particle diameter of the resin fine particles is not particularly limited as long as the object of the present invention is not impaired, and is preferably 50 nm or more and 300 nm or less, and more preferably 100 nm or more and 150 nm or less. The average particle size of the resin fine particles can be adjusted by adjusting the polymerization conditions or by a known pulverization method or classification method. When resin fine particles having such a particle size are used, it is easy to form a shell layer having a desired structure on the surface of the toner core particles. The average particle diameter of the resin fine particles can be measured as a volume average diameter using a laser diffraction / scattering particle size distribution measuring apparatus.

  The glass transition point of the resin that is the material of the resin fine particles is not particularly limited as long as the object of the present invention is not impaired. Typically, the glass transition point is preferably 56 ° C or higher, more preferably 58 ° C or higher and 62 ° C or lower.

  The mass average molecular weight (Mw) of the resin that is the material of the resin fine particles is not particularly limited as long as the object of the present invention is not impaired. Typically, the weight average molecular weight is preferably 5,000 or more and 20,000 or less. The mass average molecular weight (Mw) of the resin that is the material of the resin fine particles can be measured by gel permeation chromatography according to a conventionally known method.

(External additive)
The electrostatic latent image developing toner of the present invention can be treated with an external additive as desired after forming a shell layer on the surface of the toner core particles. Hereinafter, the particles to be treated with the external additive are also referred to as “toner mother particles”.

  The type of external additive is not particularly limited as long as it does not impair the object of the present invention, and can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include metal oxides such as silica, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more.

  The particle diameter of the external additive is not particularly limited as long as it does not impair the object of the present invention, and typically 0.01 μm or more and 1.0 μm or less is preferable.

  The amount of the external additive used is not particularly limited as long as the object of the present invention is not impaired. Typically, the amount of the external additive used is preferably 0.1 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the toner base particles produced by forming a shell layer on the surface of the toner core particles. 2 mass parts or more and 5 mass parts or less are more preferable. If the amount of the external additive used is too small, the hydrophobicity of the toner tends to decrease. As a result, it is easily affected by water molecules in the air in a high temperature and high humidity environment, and problems such as an extreme decrease in toner charge amount, a decrease in image density, and a decrease in toner fluidity are likely to occur. . Further, if the amount of the external additive used is excessive, the image density may be lowered due to excessive charge-up of the toner.

[Carrier]
The toner for developing an electrostatic latent image can be mixed with a desired carrier and used as a two-component developer. When preparing a two-component developer, it is preferable to use a magnetic carrier as a carrier.

  Suitable carriers when the electrostatic latent image developing toner of the present invention is used as a two-component developer include those in which a carrier core material is coated with a resin. Specific examples of the carrier core material include particles such as iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, and cobalt, and these materials and metals such as manganese, zinc, and aluminum. Alloy particles, particles such as iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, titanate Ceramic particles such as lithium, lead titanate, lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate, Rochelle salt, and the above magnetic particles in resin And a resin carrier in which is dispersed.

  Specific examples of the resin covering the carrier include (meth) acrylic polymers, styrene polymers, styrene- (meth) acrylic copolymers, olefin polymers (such as polyethylene, chlorinated polyethylene, and polypropylene). Substance), polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluorine resin (polytetrafluoroethylene, polychlorotrifluoroethylene, Substances such as polyvinylidene fluoride), phenol resins, xylene resins, diallyl phthalate resins, polyacetal resins, and amino resins. These resins can be used in combination of two or more.

  The particle diameter of the carrier is not particularly limited as long as the object of the present invention is not impaired. The particle diameter measured by an electron microscope is preferably 20 μm or more and 200 μm or less, more preferably 30 μm or more and 150 μm or less.

The apparent density of the carrier is not particularly limited as long as the object of the present invention is not impaired. The apparent density varies depending on the composition of the carrier and the surface structure, but typically it is preferably 2400 kg / m ³ or more and 3000 kg / m ³ or less.

  When the electrostatic latent image developing toner of the present invention is used as a two-component developer, the toner content is preferably 1% by mass or more and 20% by mass or less, and preferably 3% by mass or more with respect to the mass of the two-component developer. 15 mass% or less is preferable. By setting the toner content in the two-component developer within such a range, an appropriate image density can be maintained, and contamination of the image forming apparatus and toner adhesion to the transfer paper can be suppressed by suppressing toner scattering.

[Method for producing toner for developing electrostatic latent image]
The method for producing the electrostatic latent image developing toner described above is not particularly limited as long as the toner core particles and the shell layer are formed to have a predetermined structure. A preferred method for producing the electrostatic latent image developing toner described above includes a method including the following steps 1) and 2).
1) a step of dispersing toner core particles including at least a binder resin, a colorant, and a release agent in an air flow having a flow velocity of 30 m / s or more; and 2) containing resin fine particles in the air flow in which the toner core particles are dispersed. Spraying an aqueous emulsion.

  In addition to the steps 1) and 2), the method for producing the toner for developing an electrostatic latent image may include a drying step and an external addition step of treating the toner base particles with an external additive. Hereinafter, the surface reforming apparatus which is a suitable apparatus that can be used in step 1), step 2), drying step, external addition treatment step, and step 1) and step 2) will be described in order.

[Process 1)]
In step 1), toner core particles containing at least a binder resin, a colorant, and a release agent are used. The method for producing toner core particles is not particularly limited as long as predetermined components can be uniformly mixed, and can be appropriately selected from methods conventionally known as methods for producing toner particles containing a binder resin, a colorant, and a release agent.

  As a suitable method for producing toner core particles, a binder resin, a colorant, a release agent, and an arbitrary component such as magnetic powder are mixed by a mixer, and then the obtained mixture is melt-kneaded, A method of pulverizing and classifying the melt-kneaded product is exemplified.

  In step 1), the toner core particles are dispersed in an air flow having a flow velocity of 30 m / s or more. By causing the toner core particles to flow in an air flow having a flow rate of 30 m / s or more, when the aqueous emulsion is sprayed toward the toner core particles dispersed in the air flow in Step 2) described later, the resin fine particles contained in the aqueous emulsion Can be adhered to the surface of the toner core particles without agglomeration.

  Step 1) and step 2) are usually performed using the same apparatus. The apparatus that can be used in the steps 1) and 2) can generate an air flow having a predetermined flow velocity, and sprays an aqueous emulsion containing resin fine particles toward the toner core particles dispersed in the air flow. There is no particular limitation as long as it is provided. Specific examples of the apparatus that can be used in step 1) include a surface modification apparatus such as a hybridization system (manufactured by Nara Machinery Co., Ltd.).

[Step 2)]
In step 2), an aqueous emulsion containing resin fine particles is sprayed on the toner core particles dispersed in the airflow in step 1). The aqueous emulsion containing the resin fine particles may contain a charge control agent as an optional component. In this case, the aqueous emulsion sprayed onto the toner core particles may contain the charge control agent as fine particles separate from the resin fine particles, or may contain fine particles of the resin composition containing the charge control agent. .
The aqueous emulsion sprayed toward the toner core particles moves to the toner core particles together with a high-speed air stream without agglomeration of resin fine particles. For this reason, the entire surface of the toner core particles is uniformly coated with the resin fine particles by the step 2). On the surface of the toner core particles coated with the resin fine particles, the liquid contained in the aqueous emulsion moves to the outside of the toner through minute gaps between the resin fine particles due to capillary action, and at that time, cohesive force is generated between the resin fine particles. Further, the resin fine particles on the surface of the toner core particles are subjected to a large external force by the air flow because the toner core particles are moving at high speed in the air flow. By these forces, the resin fine particles adhering to the surface of the toner core particles are deformed and uniformly united to form a shell layer so that the interface between the resin fine particles disappears.

  The method for producing an aqueous emulsion of resin fine particles is not particularly limited, and can be appropriately selected from conventionally known methods. As a specific method for producing an aqueous emulsion of resin fine particles, a resin or a coarsely pulverized product of a charge control agent-containing resin composition, if it contains a charge control agent, is applied to an aqueous medium so as to have a desired solid content concentration. In addition, a surfactant is added if necessary, and the mixture is heated to a temperature higher by 10 ° C. or more than the softening point of the resin measured with a flow tester. The method of manufacturing by giving a shearing force is mentioned. As a stirring device used when resin fine particles are stirred in an aqueous medium to obtain an aqueous emulsion of resin fine particles, for example, a high-speed stirring device equipped with a temperature controller (Nanomizer (NV-200 (manufactured by Yoshida Machine Industry Co., Ltd.)) ))) Is preferred. The average particle diameter of the resin fine particles in the aqueous emulsion is preferably from 50 nm to 300 nm, more preferably from 100 nm to 150 nm.

  The solid content concentration of the resin fine particles in the aqueous emulsion is not particularly limited as long as the object of the present invention is not impaired, but is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 20% by mass or less. By using such an aqueous emulsion of resin fine particles having a solid content concentration, it is easy to uniformly coat the toner core particles with the resin fine particles in step 2), and to form a shell layer having a desired shape.

  The aqueous medium contained in the aqueous emulsion is usually water. The aqueous medium contained in the aqueous emulsion may contain a water-soluble organic solvent in addition to water as long as the object of the present invention is not impaired. The content of the water-soluble organic solvent in the case where the aqueous medium contains a water-soluble organic solvent is not particularly limited as long as the object of the present invention is not impaired, but is usually preferably 20% by mass or less in the aqueous medium, and 10% by mass or less. Is more preferable, and 5% by mass or less is particularly preferable.

  The temperature of the aqueous emulsion to be sprayed is not particularly limited as long as the object of the present invention is not impaired, but is preferably 30 ° C. or higher and 100 ° C. or lower, more preferably 40 ° C. or higher and 80 ° C. or lower.

[Drying process]
According to the method including Step 1) and Step 2) described above, the aqueous medium in the aqueous emulsion is generally removed from the toner, and thus it is often unnecessary to dry the resulting toner. However, depending on the conditions of step 1) and step 2), an aqueous medium may remain on the toner surface. In such a case, the toner obtained through the steps 1) and 2) may be further subjected to a drying step. In the drying step, the aqueous medium attached to the toner is evaporated and dried.

The drying step may be performed by introducing a gas such as dry air or dry nitrogen into the apparatus used in step 1) and step 2). The toner containing the aqueous medium is transferred to a separately prepared dryer. You may do it. As the dryer that can be used in the drying process, various dryers conventionally used for drying powders can be used. Specific examples of the dryer include a fluidized bed dryer, a kiln dryer, and a tumbler dryer. The drying step can be performed under reduced pressure for the purpose of promoting evaporation of the aqueous medium. The specific drying temperature is preferably 30 ° C. or higher and 100 ° C. or lower, and more preferably 40 ° C. or higher and 80 ° C. or lower.
[External process]

  The toner core particles coated with the shell layer obtained through the above steps may be used as toner base particles, and the toner base particles may be further subjected to an external addition process that is a process using an external additive. The method for treating the toner base particles with the external additive is not particularly limited, and the toner base particles can be treated according to a conventionally known method. Specifically, the processing conditions are adjusted so that the particles of the external additive are not buried in the toner base particles, and the toner base particles are processed with the external additive by a mixer such as a Henschel mixer or a Nauter mixer. Is called.

[Surface modification equipment]
Hereinafter, a suitably used surface modifying apparatus (hybridization system (manufactured by Nara Machinery Co., Ltd.)) as a toner production method including the above steps 1) and 2) will be described with reference to FIGS.

  FIG. 2 is a front view showing a configuration of a surface modifying apparatus suitably used in the toner production method of the present invention. FIG. 3 is a cross-sectional view of the surface modification device shown in FIG. 2 as viewed from the cutting plane line A200-A200. FIG. 4 is a schematic view of a surface modification apparatus suitably used in the toner production method of the present invention. 2 to 4 includes a powder flow path 202, a spray unit 203, a rotary stirring unit 204, a temperature adjustment jacket (not shown), a powder input unit 206, and a powder recovery unit. 207. The rotary stirring unit 204 and the powder channel 202 constitute a circulation unit.

(Powder channel)
The powder channel 202 includes a stirring unit 208 and a powder flow unit 209. The stirring unit 208 is a cylindrical container-like member having an internal space. Openings 210 and 211 are formed in the stirring unit 208 which is a rotary stirring chamber. The opening 210 is formed so as to penetrate the side wall including the surface 208a of the stirring unit 208 in the thickness direction at a substantially central portion of the surface 208a on one side in the axial direction of the stirring unit 208. In addition, the opening 211 is formed so as to penetrate the side wall including the side surface 208b of the stirring unit 208 in the thickness direction on the side surface 208b perpendicular to the one-side surface 208a of the stirring unit 208 in the thickness direction. The powder flow part 209 that is a circulation pipe has one end connected to the opening 210 and the other end connected to the opening 211. As a result, the internal space of the stirring unit 208 and the internal space of the powder flow-through unit 209 are communicated in an annular shape, and the powder flow path 202 is formed. Airflow, toner core particles, aqueous emulsion containing resin fine particles, toner core particles to which resin fine particles adhere, and toner core particles covered with a shell layer flow through the powder flow path 202. The powder flow path 202 is provided so that the direction in which the toner core particles flow is constant. Since the powder flow path 202 is annular, the toner core particles to which the resin fine particles are attached collide with the inner wall of the powder flow path 202 when flowing in the powder flow path 202. Such collision promotes deformation of the resin fine particles and promotes formation of the shell layer.

  The temperature in the powder flow path 202 is not particularly limited as long as a toner having a desired structure can be produced, but is preferably 15 ° C. or higher. The temperature in the powder flow path 202 is preferably set to be equal to or lower than the glass transition temperature of the toner core particles. The temperature in the powder flow path 202 becomes substantially uniform at any part due to the flow of toner core particles and the like. If the temperature in the flow path is too high, the toner core particles tend to soften and the toner core particles may aggregate. When the temperature is too low, it takes time to form the shell layer, and the toner productivity may be reduced. From these points, in order to prevent aggregation of the toner core particles, it is preferable to maintain the temperature of the powder flow path 202 and the rotary stirring unit 204 described later below the glass transition temperature of the toner core particles. Therefore, it is preferable to dispose a temperature adjusting jacket, which will be described later, having an inner diameter larger than the outer diameter of the powder passage tube, at least at a part of the outside of the powder passage 202 and the rotary stirring unit 204.

(Rotating stirrer)
The rotating stirring unit 204 includes a rotating shaft member 218, a disk-shaped rotating disk 219, and a plurality of stirring blades 220. The rotation shaft member 218 has an axis that coincides with the axis of the stirring unit 208 and is formed on the surface 208c on the other side in the axial direction of the stirring unit 208 so as to penetrate the side wall including the surface 208c in the thickness direction. A cylindrical rod-shaped member that is provided so as to be inserted through 221 and rotates around an axis by a motor (not shown). The rotating disk 219 is a disk-shaped member that is supported by the rotating shaft member 218 so that its axis coincides with the axis of the rotating shaft member 218 and rotates as the rotating shaft member 218 rotates. The plurality of stirring blades 220 are supported by the peripheral portion of the turntable 219 and rotate as the turntable 219 rotates.

  In step 1), the toner core particles are dispersed in an air flow having a flow rate of 30 m / sec or more. For this reason, it is preferable that the peripheral speed of the outermost periphery of the rotary stirring unit 204 is set so that an air flow having a flow rate of 35 m / sec or more is generated. The outermost periphery of the rotary stirring unit 204 is a portion 204a of the rotary stirring unit 204 having the longest distance from the axis of the rotary shaft member 218 in the direction perpendicular to the direction in which the rotary shaft member 218 of the rotary stirring unit 204 extends. Further, in order to individually disperse and flow the toner core particles, it is preferable that the toner core particles continue to flow for 10 minutes or more after the toner core particles are introduced into the powder flow path 202.

  Since the surface modifying apparatus includes the rotary stirring unit 204, the toner core particles coated with the resin fine particles are stirred while colliding with the rotating disk 219 in the vertical direction. Such collision promotes deformation and coalescence of the resin fine particles, and facilitates good formation of the shell layer.

(Spraying part)
The spray of the aqueous emulsion is performed by the spray unit 203 included in the surface modification apparatus 201 shown in FIG. The spray unit 203 is provided so as to be inserted into an opening formed in the outer wall of the powder flow path 202. In the powder flow part 209, the powder flow side closest to the opening part 211 in the flow direction of the toner core particles is provided. Provided in the section.

  The spray unit 203 sprays the aqueous emulsion in an air stream in which the toner core particles are dispersed. The spray unit 203 is a powder in which toner core particles are dispersed using a liquid storage unit that stores an aqueous emulsion, a carrier gas supply unit that supplies a carrier gas, and a mixture obtained by mixing an aqueous emulsion and a carrier gas as a spray liquid. A two-fluid nozzle for spraying into the body flow path 202.

  Compressed air or the like can be used as the carrier gas. The fine resin particles contained in the aqueous emulsion that is fed to the spray unit 203 at a constant flow rate by the liquid feed pump and sprayed by the spray unit 203 are individually dispersed in the powder channel 202 while flowing together with the toner core particles. . For this reason, when this surface modifying apparatus is used, it is easy to uniformly coat the surface of the toner core particles with resin fine particles.

  The finely dispersed resin fine particles are wet with the aqueous medium contained in the aqueous emulsion. However, when the resin fine particles adhere to the surface of the toner core particles, the aqueous medium moves to the surface of the toner core particles coated with the resin fine particles by capillary action, and moisture contained in the resin fine particles evaporates during the flow in the powder channel 202. Dried. At this time, a cohesive force is generated between the resin fine particles adjacent to each other on the surface of the toner core particle, and the resin fine particles are brought into close contact with each other so that the boundary surface between the particles disappears.

(Temperature adjustment jacket)
A temperature adjusting jacket (not shown), which is a temperature adjusting means, is provided on at least a part of the outside of the powder flow path 202, and the inside of the powder flow path 202 and the rotary stirring unit are passed through a cooling medium or a heating medium into the space inside the jacket. The inside of 204 is adjusted to a predetermined temperature. As a result, the temperature inside the powder flow path 202 and the outside of the rotary stirring unit 204 can be controlled to a temperature at which the toner core particles and the resin fine particles are not softened and deformed. Further, variations in temperature applied to the toner core particles and the resin fine particles are reduced, and a stable fluid state of the toner particles, the toner core particles, and the resin fine particles (hereinafter also simply referred to as toner particles) can be maintained.

  The temperature adjustment jacket is preferably provided on the entire outside of the powder flow path 202. The toner particles or the like usually collide with the inner wall of the powder flow path 202 many times, but at the time of the collision, a part of the collision energy is converted into thermal energy and accumulated in the toner particles and the like. As the number of collisions increases, the thermal energy accumulated in the toner particles and the like increases, and the toner particles and the like are eventually softened and adhere to the inner wall of the powder flow path 202. By providing the temperature adjustment jacket on the entire outside of the powder flow path 202, the adhesion force of toner particles and the like to the inner wall of the powder flow path 202 is reduced, and the toner on the inner wall of the powder flow path 202 due to a sudden rise in the temperature in the apparatus. Adherence of particles and the like can be reliably prevented, and narrowing of the powder flow path 202 due to toner particles and the like can be avoided. Therefore, the toner core particles are uniformly coated with the resin fine particles, and a toner having excellent cleaning properties can be produced with a high yield.

  Moreover, in the powder flow part 209 downstream from the spray part 203, the sprayed aqueous emulsion is not dried and remains, and if the temperature is not appropriate, the drying rate is slow and the aqueous emulsion tends to stay. When toner particles or the like come into contact with the toner particles, the toner particles easily adhere to the inner wall of the powder flow path 202, and become a toner aggregation generation source. On the inner wall near the opening 210, the toner core particles flowing into the stirring unit 208 collide with the toner core particles flowing in the stirring unit 208 by stirring by the rotary stirring unit 204, and the collided toner core particles adhere to the vicinity of the opening 210. It's easy to do. Therefore, by providing a temperature adjustment jacket at a portion where such toner particles or the like are likely to adhere, adhesion of toner particles or the like to the inner wall of the powder flow path 202 can be prevented more reliably.

(Powder input part and powder recovery part)
A powder input unit 206 and a powder recovery unit 207 are connected to the powder flow unit 209 of the powder channel 202. FIG. 4 is a side view showing the configuration around the powder input unit 206 and the powder recovery unit 207.

  The powder input unit 206 includes a hopper (not shown) that supplies toner core particles, a supply pipe 212 that communicates the hopper and the powder flow path 202, and an electromagnetic valve 213 provided in the supply pipe 212. The toner core particles supplied from the hopper are supplied to the powder flow path 202 through the supply pipe 212 in a state where the flow path in the supply pipe 212 is opened by the electromagnetic valve 213. The toner core particles supplied to the powder flow path 202 flow in a certain powder flow direction by stirring by the rotary stirring unit 204. Further, when the flow path in the supply pipe 212 is closed by the electromagnetic valve 213, the toner core particles are not supplied to the powder flow path 202.

  The powder recovery unit 207 includes a recovery tank 215, a recovery pipe 216 that communicates the recovery tank 215 and the powder flow path 202, and an electromagnetic valve 217 provided in the recovery pipe 216. In a state where the flow path in the collection pipe 216 is opened by the electromagnetic valve 217, the toner particles flowing through the powder flow path 202 are collected in the collection tank 215 via the collection pipe 216. In addition, when the flow path in the collection pipe 216 is closed by the electromagnetic valve 217, the toner particles flowing through the powder flow path 202 are not collected.

  According to the method for producing a toner for developing an electrostatic latent image of the present invention described above, the shell layer 103 having a predetermined shape is formed so as to cover the entire surface of the toner core particle 102 as shown in FIG. The electrostatic latent image developing toner can be easily prepared.

  The toner for developing an electrostatic latent image of the present invention produced by the above method is excellent in fixability and storage stability, and can be suitably used in various image forming apparatuses.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by the Example.

[Example 1]
Hereinafter, the toner core particles and the resin fine particles used in Example 1 will be described.

(Toner core particle A)
Binder resin (polyester resin (manufactured by Kao Corporation), glass transition point (Tg) 58 ° C., melting point (Tm) 110 ° C., mass average molecular weight (Mw) 45,000) 78 mass relative to the total mass of each raw material. %, 15% by mass of a colorant (P.B15-3 (manufactured by Sanyo Pigment Co., Ltd.), Pigment Blue), 5% by mass of a release agent (ester wax, WEP-3 (manufactured by NOF Corporation)), Charge control agent (Bontron P-51 (manufactured by Orient Chemical Co., Ltd.)) 2% by mass is charged into a Henschel mixer (FM20B (manufactured by Nippon Coke Kogyo Co., Ltd.)) and mixed for 3 minutes at a rotational speed of 2,500 rpm. did. Thereafter, the obtained mixture was melt-kneaded using a twin-screw extruder (PCM-30 (manufactured by Ikegai Co., Ltd.)) under the conditions of a rotation speed of 300 rpm, a cylinder temperature of 110 ° C., and an input amount of 6 kg / hour. And the obtained melt-kneaded material was cooled so that it might become plate | board thickness of about 2 mm using the drum flaker (made by Nippon Coke Kogyo Co., Ltd.). The cooled kneaded product is coarsely pulverized by a pulverizer (Rotoplex (manufactured by Alpine)) with a screen opening of 2 mm, and the resulting coarsely pulverized product is a turbo mill (T-250 type (manufactured by Turbo Kogyo Co., Ltd.)). Was finely pulverized to obtain a finely pulverized product. The finely pulverized product was classified using an elbow jet classifier (EJ-L-3 (manufactured by Nippon Steel Mining Co., Ltd.)), and the resulting toner core particle A had a volume average particle size of 7.0 μm. The volume average particle diameter of the toner core particles A was measured with a particle size meter (Multisizer 3 (manufactured by Beckman Coulter, Inc.)).

(Resin fine particles A)
As the resin, styrene acrylic resin (glass transition point (Tg) 62 ° C., melting point (Tm) 118 ° C., mass average molecular weight (Mw) 16,000) was used, and resin fine particles were produced by the following procedure.
First, the resin was coarsely pulverized with a turbo mill (Freund Turbo, Inc.) until the volume average particle diameter was about 400 μm. Next, 150 g of coarsely pulverized resin, 15 g of sodium lauryl sulfate, and 835 g of ion-exchanged water were put into a nanomizer (NV-200 (manufactured by Yoshida Kikai Kogyo Co., Ltd.)) into which a temperature controller was introduced, and the temperature was 170 ° C. The treatment was repeated three times with the nanomizer treatment pressure set to 150 MPa, and an aqueous emulsion of resin fine particles A having a volume average particle size of 100 μm was obtained.

(Preparation of toner base particles)
Using the obtained toner core particles A and an aqueous emulsion of resin fine particles A, toner base particles having a resin fine particle coating layer formed on the surface of the toner core particles A were prepared.
Specifically, as shown in FIG. 2, a modified surface modifying device (hybridization system, NHS-1 type (manufactured by Nara Machinery Co., Ltd.) was installed by attaching a two-fluid nozzle to the upper part of the container of the surface modifying device. )), The internal temperature was set to 20 ° C., and 200 g of toner core particles A were first allowed to stay for 10 minutes while being stirred at 8000 rpm. Next, an aqueous emulsion of resin fine particles A was sprayed from a two-fluid nozzle at a feed rate of 1.5 g / min over 45 minutes. The total supply amount of the resin fine particles A as an aqueous emulsion was 70 g, and the total supply amount as a solid content was 10.5 g. After spraying of the aqueous emulsion of resin fine particles A was completed, it was allowed to flow for 10 minutes, and then the toner base particles were recovered from the surface modification device.

(External processing)
To 100 parts by mass of the obtained toner base particles, 1 part by mass of an external additive (silica: RA200 (manufactured by Nippon Aerosil Co., Ltd.)) was added, and a Henschel mixer (10C (manufactured by Mitsui Mining Co., Ltd.)) was used. Processing was performed under conditions of a jacket temperature of 20 ° C. and a stirring time of 2 minutes to obtain an externally added toner.

≪Evaluation≫
Using the obtained toner, the fixability and heat-resistant storage stability were evaluated according to the following methods. The evaluation results are shown in Table 1.

(Preservation evaluation)
3 g of toner is weighed into a 20 cc plastic bottle and leveled in a 25 ° C., 50% RH environment for 12 hours. Next, according to the manual of a powder tester (manufactured by Hosokawa Micron Co., Ltd.), the toner is sieved using a 140 mesh (105 μm mesh) sieve under the conditions of a rheostat scale of 3.5 and a time of 30 seconds. (%) Was obtained and evaluated according to the following criteria.
(Cohesion calculation formula)
Aggregation degree (%) = toner mass remaining on sieve / toner mass before sieving × 100
○ (Pass): Aggregation degree is 15% by mass or less.
X (failure): Aggregation degree exceeds 15 mass%.

(Fixability evaluation)
Using a printer (FS-C5200DN (manufactured by Kyocera Document Solutions Co., Ltd.)) as an evaluation machine, a solid image of 2.5 cm × 2.5 cm on the recording medium so that the toner loading amount is 1.5 mg / cm ^2. An unfixed image was output. Next, the fixing device of the printer is used as a fixing jig, the solid unfixed image is set to a linear speed of 170 mm / second, the fixing temperature of the fixing device is set to a low fixing temperature (when the fixing temperature is 160 ° C.), Fixing was performed at a high fixing temperature (when the fixing temperature was 200 ° C.). Using images fixed at the respective fixing temperatures, the presence or absence of occurrence of an offset was judged visually. The criteria for evaluating the fixing property are as follows.
○ (Pass): No offset occurs at a low fixing temperature and a high fixing temperature.
X (failed): Offset occurs at a low fixing temperature or a high fixing temperature.

[Example 2]
(Toner core particle B)
The toner core particle B is the same as the toner core particle A except that a polyester resin having a glass transition point (Tg) of 45 ° C., a melting point (Tm) of 105 ° C., and a weight average molecular weight (Mw) of 40,000 is used as the binder resin. Got.

(Resin fine particles B)
An aqueous emulsion of resin fine particles B was obtained in the same manner as the resin fine particles A except that the processing pressure of the nanomizer was changed to 190 MPa.

  Except for using the toner core particle B and the aqueous emulsion of the resin fine particles B, toner base particles were prepared and externally added in the same manner as in Example 1 to obtain the toner of Example 2. The obtained toner was evaluated for fixability and heat-resistant storage stability. The evaluation results are shown in Table 1.

Example 3
(Toner core particle C)
The toner core particle C is the same as the toner core particle A except that a polyester resin having a glass transition point (Tg) of 65 ° C., a melting point (Tm) of 120 ° C., and a weight average molecular weight (Mw) of 50,000 is used as the binder resin. Got.

(Resin fine particles C)
An aqueous emulsion of resin fine particles C was obtained in the same manner as the resin fine particles A except that the processing pressure of the nanomizer was changed to 80 MPa.

  Except for using the toner core particles C and the aqueous emulsion of the resin fine particles C, toner base particles were prepared and externally added in the same manner as in Example 1 to obtain the toner of Example 3. The obtained toner was evaluated for fixability and heat-resistant storage stability. The evaluation results are shown in Table 1.

Example 4
The toner core particle B obtained in Example 2 and the aqueous emulsion of resin fine particles A obtained in Example 1 were used, except that the total supply amount of the aqueous emulsion of resin fine particles A was 37.5 g. In the same manner as in Example 1, toner base particles were prepared and externally added to obtain a toner of Example 4. The obtained toner was evaluated for fixability and heat-resistant storage stability. The evaluation results are shown in Table 1.

Example 5
(Resin fine particles D)
An aqueous emulsion of resin fine particles D was obtained in the same manner as the resin fine particles A except that the processing pressure of the nanomizer was 120 MPa.

  In the same manner as in Example 1, except that the toner core particles C obtained in Example 3 and the aqueous emulsion of the resin fine particles D described above were used and the total supply amount of the aqueous emulsion was 140 g. Preparation and external treatment were performed to obtain a toner of Example 5. The obtained toner was evaluated for fixability and heat-resistant storage stability. The evaluation results are shown in Table 1.

[Comparative Example 1]
(Resin fine particles E)
The aqueous emulsion of resin fine particles A was dehydrated and dried using a dryer MDL-050 (trade name, manufactured by Fujisaki Electric Co., Ltd.) to obtain resin fine particles E.

  150 g of the obtained resin fine particles E were added to 850 g of ethanol to prepare an emulsion of resin fine particles E. In the same manner as in Example 1, except that the toner core particles A obtained in Example 1 and the emulsion of the resin fine particles E are used, toner mother particles are prepared and externally added. A toner was obtained. The obtained toner was evaluated for fixability and heat-resistant storage stability. The evaluation results are shown in Table 1.

≪Confirmation of shell layer structure≫
According to the following method, the surfaces of the toners of Examples 1 to 5 and Comparative Example 1 were observed using a scanning electron microscope (SEM), and the coating state of the toner core particles with the shell layer, the surface state of the shell layer, It was confirmed. Further, according to the following method, a photograph of a cross section of the toner was taken using a transmission electron microscope (TEM). Using the obtained TEM photograph, the surface state of the shell layer, the state inside the shell layer, and the shape of the inner surface of the shell layer were confirmed, and the thickness of the shell layer was measured. A TEM photograph of the cross section of the toner used in Example 1 is shown in FIG.

<Method for observing toner surface>
The surface of the toner particles was observed at a magnification of 10,000 using a scanning electron microscope (JSM-6700F (manufactured by JEOL Ltd.)).

<Method for photographing the cross section of the toner>
A sample in which the toner was embedded in a resin was prepared. Using a microtome (EM UC6 (manufactured by Leica Co., Ltd.)), a thin piece sample for cross-sectional observation of 200 nm thick toner was prepared from the obtained sample. The obtained flake sample was observed at a magnification of 50,000 times using a transmission electron microscope (TEM, JSM-6700F (manufactured by JEOL Ltd.)), and an image of a cross section of an arbitrary toner was taken.

  When the surface of Examples 1 to 5 was observed with a scanning electron microscope (SEM), toner particles having a particle diameter of 6 μm or more and 8 μm or less were used to form a shell layer on the surface of the shell layer. No substantially spherical particles derived from the resin fine particles were observed. Further, from the TEM photograph of the cross section of the toner used in Example 1 shown in FIG. 5, the shell layer of the toner used in Example 1 does not contain substantially spherical particles, and the outer surface thereof is smooth. confirmed. From the TEM photograph of the cross section of the toner used in Example 1, no cracks in the direction substantially perpendicular to the surface of the toner core particles were observed in the toner shell layer used in Example 1.

  On the other hand, when scanning electron microscope observation (SEM) was performed on the surface of Comparative Example 1, for the toner particles having a particle diameter of 6 μm or more and 8 μm or less, the resin used for forming the shell layer in the shell layer Substantially spherical particles derived from the fine particles were observed.

  According to Examples 1 to 5, the toner core particles including at least a binder resin, a colorant, and a release agent, and a shell layer that covers the entire surface of the toner core particles are used, and a scanning electron microscope is used. When observing the cross section using a transmission electron microscope, the shell layer does not show substantially spherical particles derived from resin fine particles in the shell layer of toner particles having a particle diameter in a specific range. In the toner, no cracks are observed in a direction substantially perpendicular to the surface of the toner core particles, and an image is formed using a toner in which the glass transition point (Tg) of the binder resin and the thickness of the shell layer are within a predetermined range. In this case, a toner excellent in fixability and heat-resistant storage stability can be obtained.

  According to Comparative Example 1, when ethanol is used as the solvent for the resin fine particle emulsion, the heat-resistant storage stability of the toner tends to decrease. In this case, when ethanol is used as the solvent of the resin fine particle emulsion, the resin fine particles are more easily dried than when water is used as the solvent. Therefore, it is presumed that the substantially spherical particles derived from the shape of the resin fine particles are likely to remain in the shell layer of the toner, and the toner component is likely to exude from the interface of the substantially spherical particles.

DESCRIPTION OF SYMBOLS 101 Toner for electrostatic latent image development 102 Toner core particle 103 Coating layer 104 Interface surface 201 Surface modification device 202 Powder flow path 203 Spraying part 204 Rotating stirring part 206 Powder input part 207 Powder recovery part 208 Stirring part 209 Powder Flowing part 210, 211 Opening part 212 Supply pipe 213, 217 Solenoid valve 215 Collection tank 216 Collection pipe 218 Rotating shaft member 219 Rotary plate 220 Stirring blade 221 Through-hole

Claims (7)

Toner core particles containing at least a binder resin, a colorant, and a release agent;
An electrostatic latent image developing toner comprising a shell layer covering the entire surface of the toner core particles,
The initial shell layer is formed using spherical resin fine particles,
When the surface of the toner for developing an electrostatic latent image is observed using a scanning electron microscope, a structure derived from the spherical resin fine particles in the shell layer is observed for toner particles having a particle diameter of 6 μm or more and 8 μm or less. not,
When the cross section of the electrostatic latent image developing toner is observed using a transmission electron microscope, a clear boundary surface is observed between the toner core particles and the shell layer, and the inside of the shell layer is observed. In addition, cracks in a direction substantially perpendicular to the surface of the toner core particles are not observed,
Toner for electrostatic latent image development.   The electrostatic latent image developing toner according to claim 1, wherein the shell layer has a thickness of 30 to 300 nm. The method for producing a toner for developing an electrostatic latent image according to claim 1, comprising the following steps 1) and 2):
1) a step of dispersing toner core particles containing at least a binder resin, a colorant, and a release agent in an air flow having a flow rate of 30 m / s or more;
2) A step of spraying an aqueous emulsion containing resin fine particles in an air stream in which the toner core particles are dispersed.   The method for producing a toner for developing an electrostatic latent image according to claim 3, wherein in the step 1), the toner core particles are dispersed in an airflow circulating in an annular flow path.   5. The method for producing a toner for developing an electrostatic latent image according to claim 4, wherein, in the step 1), the air flow is generated by a rotary stirring unit provided in the middle of the circulation path of the annular flow path.   The method for producing a toner for developing an electrostatic latent image according to claim 3, wherein the aqueous emulsion contains a surfactant.   The method for producing a toner for developing an electrostatic latent image according to claim 3, wherein the solid content concentration of the aqueous emulsion is 5% by mass or more and 50% by mass or less.