WO2012002278A1 - 静電荷像現像用トナー - Google Patents
静電荷像現像用トナー Download PDFInfo
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- WO2012002278A1 WO2012002278A1 PCT/JP2011/064554 JP2011064554W WO2012002278A1 WO 2012002278 A1 WO2012002278 A1 WO 2012002278A1 JP 2011064554 W JP2011064554 W JP 2011064554W WO 2012002278 A1 WO2012002278 A1 WO 2012002278A1
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- fine particles
- toner
- core
- composite fine
- particles
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09307—Encapsulated toner particles specified by the shell material
- G03G9/09342—Inorganic compounds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/0827—Developers with toner particles characterised by their shape, e.g. degree of sphericity
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09307—Encapsulated toner particles specified by the shell material
- G03G9/09314—Macromolecular compounds
- G03G9/09321—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09307—Encapsulated toner particles specified by the shell material
- G03G9/09314—Macromolecular compounds
- G03G9/09328—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09392—Preparation thereof
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/097—Plasticisers; Charge controlling agents
- G03G9/09708—Inorganic compounds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/097—Plasticisers; Charge controlling agents
- G03G9/09708—Inorganic compounds
- G03G9/09716—Inorganic compounds treated with organic compounds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/097—Plasticisers; Charge controlling agents
- G03G9/09708—Inorganic compounds
- G03G9/09725—Silicon-oxides; Silicates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/70—Nanostructure
- Y10S977/773—Nanoparticle, i.e. structure having three dimensions of 100 nm or less
Definitions
- the present invention is an electrostatic charge image developing toner (hereinafter, sometimes simply referred to as “toner”) used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like. About.
- an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and an electrostatic printing apparatus
- a desired image is formed by developing an electrostatic latent image formed on a photoreceptor with toner for developing an electrostatic image.
- This technique is widely used. Such a technique is applied to a copying machine, a printer, a facsimile machine, and a multifunction machine of these.
- an electrophotographic apparatus using an electrophotographic method generally forms the electrostatic latent image on the photoreceptor after the surface of the photoreceptor made of a photoconductive material is uniformly charged by various means. . Next, the electrostatic latent image is developed using toner, the toner image is transferred onto a recording material such as paper, and then fixed by heating or the like to obtain a copy.
- the toner used for development includes a negatively chargeable toner and a positively chargeable toner.
- An electrophotographic apparatus using a positively chargeable toner has been used preferably in recent years because it generates less ozone and provides good chargeability.
- inorganic fine particles and organic fine particles generally having a smaller particle diameter than colored resin particles (toner particles). External additives such as these are externally added (attached).
- the external additive In the conventional toner, in the process of continuous printing of a large number of sheets, the external additive is moved from the surface of the toner particles to the inside due to mechanical stress in the developing device (increase in the number of contact between the toner particles due to stirring or the like). Buried and / or released (desorbed) from the surface of the toner particles. For this reason, the function of the external additive is lowered, and it becomes difficult to impart to the toner particles a stable charging property (charging stability) over time.
- the toner particles embedded with the external additive cause a phenomenon (filming phenomenon) in which the toner particles adhere to the surface of the photoreceptor, and the image quality is liable to deteriorate due to fog or the like.
- the external additive released (desorbed) from the surface of the toner particles deteriorates the charging characteristics of the surface of the photoreceptor, and causes the printing durability and image quality of the toner to deteriorate. In particular, under high temperature and high humidity conditions, the image quality is significantly deteriorated by filming.
- Patent Document 1 discloses a toner using inorganic / organic composite fine particles in which inorganic fine particles are fixed on the surface of organic fine particles as an external additive.
- Patent Document 2 discloses a toner containing resin fine particles having a specific average particle diameter and having a surface covered with a continuous layer of silica as an external additive.
- Patent Document 1 in paragraph [0064] of the specification of the document, as a means for fixing inorganic fine particles to the surface of organic fine particles, a method of mixing organic fine particles and inorganic fine particles and then applying heat, organic fine particles And so-called mechanochemical method for mechanically fixing inorganic fine particles to the surface of the film.
- a manufacturing method it is difficult to cover the entire surface of the organic fine particles serving as the core with inorganic fine particles.
- the toner described in Patent Document 1 is likely to cause fogging, particularly fogging under high temperature and high humidity.
- Claim 6 of Patent Document 2 describes that the abundance ratio of silicon atoms on the surface of the external additive is 0.1 to 10.0% by mass.
- the thickness of the silica shell is too thin, the contribution of the effect of the silica shell to the entire external additive is small, and therefore, the chargeability in a low temperature and low humidity environment is hardly exhibited.
- a first object of the present invention is to provide a toner for developing an electrostatic charge image that suppresses a decrease in toner charge amount and occurrence of fogging in a high temperature and high humidity environment and is excellent in fluidity.
- a second object of the present invention is to provide a toner for developing an electrostatic charge image that suppresses generation of fog in a high temperature and high humidity environment and has excellent fine line reproducibility in a low temperature and low humidity environment.
- the present inventors diligently studied to achieve the above object, and as an external additive, by using core-shell composite fine particles in which the surface of the resin fine particles is coated with silica, alumina, titania and / or zirconia. And found that the environmental stability of the toner is increased.
- the present inventors use the core-shell type composite fine particles in which the surface of the resin fine particles is coated with silica, thereby suppressing the decrease in the toner charge amount in a high temperature and high humidity environment.
- the present inventors have found that stable printing can be performed, and that a very high toner fluidity is exhibited, so that a good image quality can be obtained.
- the present inventors can suppress an increase in toner charge amount in a low-temperature and low-humidity environment by using core-shell type composite particles in which the surface of the resin particles is coated with alumina, titania and / or zirconia.
- the present invention was completed by finding that stable printing can be performed without losing fine line reproducibility even in the same environment, and that there is no printing defect caused by an increase in the charge amount, and that good image quality can be obtained. It came to do.
- the electrostatic image developing toner of the present invention is a toner for developing an electrostatic image containing a colored resin particle containing a binder resin and a colorant and an external additive, wherein the external additive is a resin.
- the core-shell type composite fine particles are coated with at least one inorganic component selected from the group consisting of silica, alumina, titania and zirconia, and the total volume of the core-shell type composite fine particles is 100% by volume.
- the volume ratio of the inorganic component of the core-shell composite fine particles is 45 to 75% by volume.
- the adsorbed water content of the core-shell type composite fine particles is 0.5 to 2.5% by mass.
- the addition amount of the core-shell composite fine particles is 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles.
- the colored resin particles have a volume average particle diameter of 4 to 12 ⁇ m and an average circularity of 0.96 to 1.00.
- both the colored resin particles and the core-shell composite fine particles exhibit positive chargeability.
- the core-shell composite fine particles preferably have a number average particle size of 30 to 300 nm.
- the resin fine particles of the core-shell type composite fine particles are preferably a crosslinked resin.
- the toner for developing an electrostatic charge image of the present invention by using the core-shell type composite fine particles in which the surface of the resin fine particles is coated with silica as an external additive, the toner has stable charging characteristics over time. Even if it is applied to particles and subjected to continuous printing of a large number of sheets, image quality deterioration due to fog or the like hardly occurs and an electrostatic charge image developing toner having further excellent fluidity is provided. Further, according to the electrostatic image developing toner of the present invention as described above, by using the core-shell type composite fine particles in which the surface of the resin fine particles is coated with alumina, titania and / or zirconia as the external additive.
- the increase in the toner charge amount in a low-temperature and low-humidity environment is suppressed, stable printing can be performed without losing fine line reproducibility even in the same environment, and there are no printing defects caused by the increase in the charge amount.
- a toner for developing an electrostatic image capable of obtaining a satisfactory image quality.
- the electrostatic image developing toner of the present invention is a colored resin particle containing a binder resin and a colorant, and an electrostatic image developing toner containing an external additive, wherein the external additive is a resin fine particle.
- the surface is a core-shell composite fine particle coated with at least one inorganic component selected from the group consisting of silica, alumina, titania and zirconia, and the total volume of the core-shell composite fine particle is 100% by volume
- the volume ratio of the inorganic component of the core-shell composite fine particles is 45 to 75% by volume.
- the toner of the present invention contains colored resin particles containing a binder resin and a colorant, and core-shell type composite particles in which the surface of the resin fine particles is coated with silica, alumina, titania and / or zirconia as an external additive. .
- the toner of the present invention is preferably obtained by adhering and adding the core-shell type composite fine particles as an external additive to the surface of the colored resin particles.
- a method for producing colored resin particles used in the present invention a colored resin particle obtained by the production method, a method for producing core-shell composite fine particles used as an external additive in the invention, and a core shell obtained by the production method
- the production method of the toner of the present invention using the mold composite fine particles, the colored resin particles and the external additive, and the toner of the present invention will be described in order.
- the production method of colored resin particles is roughly classified into dry methods such as a pulverization method, and wet methods such as an emulsion polymerization aggregation method, a suspension polymerization method, and a dissolution suspension method.
- the wet method is preferable because it is easy to obtain a toner excellent in printing characteristics such as the property.
- a polymerization method such as an emulsion polymerization aggregation method and a suspension polymerization method is preferable because a toner having a relatively small particle size distribution on the order of microns is preferable.
- a suspension polymerization method is more preferable among polymerization methods. preferable.
- an emulsified polymerizable monomer is polymerized to obtain a resin fine particle emulsion, which is aggregated with a colorant dispersion or the like to produce colored resin particles.
- the dissolution suspension method produces droplets of a solution in which toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent in an aqueous medium, and the organic solvent is removed to produce colored resin particles.
- toner components such as a binder resin and a colorant are dissolved or dispersed in an organic solvent in an aqueous medium, and the organic solvent is removed to produce colored resin particles.
- the colored resin particles of the present invention can be produced by employing a wet method or a dry method.
- a wet method a preferred suspension polymerization method is adopted, and the following process is performed.
- A) Suspension polymerization method (A-1) Preparation step of polymerizable monomer composition First, a polymerizable monomer, a colorant, and a charge control agent and a release agent added as necessary Other additives are mixed to prepare a polymerizable monomer composition. The mixing at the time of preparing the polymerizable monomer composition is performed using, for example, a media type dispersing machine.
- the polymerizable monomer means a monomer having a polymerizable functional group, and the polymerizable monomer is polymerized to become a binder resin. It is preferable to use a monovinyl monomer as the main component of the polymerizable monomer.
- the monovinyl monomer examples include styrene; styrene derivatives such as vinyl toluene and ⁇ -methylstyrene; acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid 2
- Acrylic esters such as ethylhexyl and dimethylaminoethyl acrylate
- methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate
- acrylonitrile And nitrile compounds such as methacrylonitrile
- amide compounds such as acrylamide and methacrylamide
- olefins such as ethylene, propylene, and butylene.
- a crosslinkable polymerizable monomer means a monomer having two or more polymerizable functional groups.
- the crosslinkable polymerizable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; alcohols having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate; Examples include ester compounds in which two or more carboxylic acids are ester-bonded; other divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups.
- crosslinkable polymerizable monomers can be used alone or in combination of two or more.
- the crosslinkable polymerizable monomer is usually used in a proportion of 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass, with respect to 100 parts by mass of the monovinyl monomer. desirable.
- the macromonomer has a polymerizable carbon-carbon unsaturated double bond at the end of the molecular chain, and is a reactive oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000.
- the macromonomer is preferably one that gives a polymer having a higher Tg than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer (hereinafter sometimes referred to as “Tg”).
- Tg the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer
- the macromonomer is preferably used in an amount of 0.03 to 5 parts by mass, more preferably 0.05 to 1 part by mass, with respect to 100 parts by mass of the monovinyl monomer.
- a colorant is used.
- black, cyan, yellow, and magenta colorants can be used.
- the black colorant carbon black, titanium black, magnetic powder such as iron zinc oxide and nickel iron oxide can be used.
- cyan colorant for example, a copper phthalocyanine compound, a derivative thereof, and an anthraquinone compound can be used. Specifically, C.I. I. Pigment blue 2, 3, 6, 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 17: 1, 60, and the like.
- yellow colorant examples include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments.
- monoazo pigments examples include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments.
- azo pigments such as disazo pigments
- condensed polycyclic pigments examples include compounds such as monoazo pigments, azo pigments such as disazo pigments, and condensed polycyclic pigments.
- magenta colorant monoazo pigments, azo pigments such as disazo pigments, and compounds such as condensed polycyclic pigments are used.
- monoazo pigments such as disazo pigments
- compounds such as condensed polycyclic pigments are used.
- each colorant can be used alone or in combination of two or more.
- the amount of the colorant is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the monovinyl monomer.
- a positively or negatively chargeable charge control agent can be used to improve the chargeability of the toner.
- the charge control agent is not particularly limited as long as it is generally used as a charge control agent for toner, but among charge control agents, the compatibility with the polymerizable monomer is high, and stable chargeability. (Charge stability) can be imparted to the toner particles, and therefore a positively or negatively chargeable charge control resin is preferable. Further, from the viewpoint of obtaining a positively chargeable toner, a positively chargeable charge control resin is preferable. More preferably used.
- positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salts, triaminotriphenylmethane compounds and imidazole compounds, polyamine resins as charge control resins that are preferably used, and quaternary ammonium group-containing copolymers. , And quaternary ammonium base-containing copolymers.
- Negatively chargeable charge control agents include azo dyes containing metals such as Cr, Co, Al, and Fe, salicylic acid metal compounds and alkylsalicylic acid metal compounds, and sulfonic acid group containing charge control resins that are preferably used Examples thereof include a copolymer, a sulfonate group-containing copolymer, a carboxylic acid group-containing copolymer, and a carboxylic acid group-containing copolymer.
- the charge control agent in a proportion of usually 0.01 to 10 parts by mass, preferably 0.03 to 8 parts by mass with respect to 100 parts by mass of the monovinyl monomer. If the addition amount of the charge control agent is less than 0.01 parts by mass, fog may occur. On the other hand, when the addition amount of the charge control agent exceeds 10 parts by mass, printing stains may occur.
- a molecular weight modifier when polymerizing a polymerizable monomer that is polymerized to become a binder resin.
- the molecular weight modifier is not particularly limited as long as it is generally used as a molecular weight modifier for toners.
- t-dodecyl mercaptan t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and 2,2, Mercaptans such as 4,6,6-pentamethylheptane-4-thiol; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, N, N′-dimethyl-N, N′-diphenylthiuram disulfide, N, And thiuram disulfides such as N′-dioctadecyl-N, N′-diisopropylthiuram disulfide;
- molecular weight modifiers may be used alone or in combination of two or more. In the present invention, it is desirable to use the molecular weight adjusting agent in a proportion of usually 0.01 to 10 parts by mass,
- a release agent as another additive.
- a release agent By adding a release agent, the releasability of the toner from the fixing roll during fixing can be improved.
- Any releasing agent can be used without particular limitation as long as it is generally used as a releasing agent for toner.
- low molecular weight polyolefin wax and modified wax thereof plant natural wax such as jojoba; petroleum wax such as paraffin; mineral wax such as ozokerite; synthetic wax such as Fischer-Tropsch wax; polyglycerin ester, dipentaerythritol ester, etc. Ester wax; and the like.
- An ester wax is preferable because a balance between the storage stability of the toner and the low-temperature fixability is achieved, and among them, a polyhydric alcohol ester is preferable. These may be used alone or in combination of two or more.
- the release agent is preferably used in an amount of 0.1 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the monovinyl monomer.
- A-2 Suspension step for obtaining a suspension (droplet formation step)
- a polymerizable monomer composition containing a polymerizable monomer and a colorant is dispersed in an aqueous medium containing a dispersion stabilizer, a polymerization initiator is added, and then the polymerizable monomer composition is added.
- Droplet formation is performed.
- the method for forming droplets is not particularly limited.
- an (in-line type) emulsifying disperser (trade name “Milder” manufactured by Ebara Manufacturing Co., Ltd.), a high-speed emulsifying disperser (trade name “T. K. Homomixer MARK Type II ”) or the like capable of strong stirring.
- persulfates such as potassium persulfate and ammonium persulfate: 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-methyl-N- (2- Hydroxyethyl) propionamide), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobisisobutyro Azo compounds such as nitriles; di-t-butyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-hexylperoxy-2-ethylbutanoate, diisopropyl peroxydicarbonate, Organic peroxides such as di-t-butylperoxyisophthalate and t-butylperoxyisobutyrate It is. These can be used alone or in combination of two or more
- peroxyesters are preferred because of the high initiator efficiency and the remaining polymerizable monomer can be reduced.
- Non-aromatic peroxyesters that is, peroxyesters having no aromatic ring Is more preferable.
- the polymerization initiator may be added before the droplet formation after the polymerizable monomer composition is dispersed in the aqueous medium. However, the polymerization initiator is not dispersed in the aqueous medium. It may be added to the monomer composition.
- the addition amount of the polymerization initiator used for the polymerization of the polymerizable monomer composition is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 100 parts by mass of the monovinyl monomer. Is 15 parts by mass, and particularly preferably 1 to 10 parts by mass.
- the aqueous medium refers to a medium containing water as a main component.
- the aqueous medium preferably contains a dispersion stabilizer.
- the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metals such as aluminum oxide and titanium oxide. Oxides; metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and ferric hydroxide; inorganic compounds such as; water-soluble polymers such as polyvinyl alcohol, methylcellulose, and gelatin; anionic surfactants; Organic compounds such as nonionic surfactants; amphoteric surfactants;
- the said dispersion stabilizer can be used 1 type or in combination of 2 or more types.
- inorganic compounds particularly colloids of poorly water-soluble metal hydroxides are preferred.
- a colloid of an inorganic compound, particularly a poorly water-soluble metal hydroxide the particle size distribution of the colored resin particles can be narrowed, and the residual amount of the dispersion stabilizer after washing can be reduced.
- the polymerized toner can reproduce an image clearly and does not deteriorate environmental stability.
- the polymerization temperature of the polymerizable monomer composition is preferably 50 ° C. or higher, more preferably 60 to 95 ° C.
- the polymerization reaction time is preferably 1 to 20 hours, and more preferably 2 to 15 hours.
- the colored resin particles may be used as a polymerized toner by adding an external additive as it is, but the so-called core-shell type obtained by using the colored resin particles as a core layer and forming a shell layer different from the core layer on the outside thereof. It is preferable to use colored resin particles (also referred to as “capsule type”).
- the core-shell type colored resin particles balance the reduction of the fixing temperature and the prevention of aggregation during storage by coating the core layer made of a material having a low softening point with a material having a higher softening point. be able to.
- the method for producing core-shell type colored resin particles using the colored resin particles described above is not particularly limited, and can be produced by a conventionally known method.
- An in situ polymerization method and a phase separation method are preferable from the viewpoint of production efficiency.
- a method for producing core-shell type colored resin particles by in situ polymerization will be described below. Addition of a polymerizable monomer (polymerizable monomer for shell) and a polymerization initiator to form a shell layer into an aqueous medium in which colored resin particles are dispersed, and then polymerize to form a core-shell type color. Resin particles can be obtained.
- the same monomers as the aforementioned polymerizable monomers can be used.
- monomers such as styrene, acrylonitrile, and methyl methacrylate, which can obtain a polymer having a Tg exceeding 80 ° C., alone or in combination of two or more.
- polymerization initiator used for polymerization of the polymerizable monomer for shell examples include persulfate metal salts such as potassium persulfate and ammonium persulfate; 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) Water-soluble such as azo initiators such as) propionamide) and 2,2′-azobis- (2-methyl-N- (1,1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide); A polymerization initiator can be mentioned. These can be used alone or in combination of two or more.
- the amount of the polymerization initiator is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer for shell.
- the polymerization temperature of the shell layer is preferably 50 ° C. or higher, more preferably 60 to 95 ° C.
- the polymerization reaction time is preferably 1 to 20 hours, and more preferably 2 to 15 hours.
- the dispersion stabilizer when an inorganic compound is used as the dispersion stabilizer, the dispersion stabilizer can be dissolved in water and removed by adding an acid or alkali to the aqueous dispersion of colored resin particles. preferable.
- a colloid of a poorly water-soluble inorganic hydroxide is used as the dispersion stabilizer, it is preferable to adjust the pH of the colored resin particle aqueous dispersion to 6.5 or less by adding an acid.
- the acid to be added inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as formic acid and acetic acid can be used. Particularly, since the removal efficiency is large and the burden on the manufacturing equipment is small, Sulfuric acid is preferred.
- dehydration and filtration methods there are no particular limitations on the dehydration and filtration methods, and various known methods can be used. Examples thereof include a centrifugal filtration method, a vacuum filtration method, and a pressure filtration method. Also, the drying method is not particularly limited, and various methods can be used.
- (B) Pulverization method When the pulverization method is used to produce colored resin particles, the following process is performed. First, a binder resin, a colorant, and other additives such as a charge control agent and a release agent added as necessary are mixed in a mixer, such as a ball mill, a V-type mixer, a Henschel mixer (trade name). Mix using a high-speed dissolver, internal mixer, Fallberg, etc. Next, the mixture obtained as described above is kneaded while being heated using a pressure kneader, a twin-screw extrusion kneader, a roller or the like.
- a mixer such as a ball mill, a V-type mixer, a Henschel mixer (trade name). Mix using a high-speed dissolver, internal mixer, Fallberg, etc.
- the obtained kneaded material is coarsely pulverized using a pulverizer such as a hammer mill, a cutter mill, or a roller mill. Furthermore, after finely pulverizing using a pulverizer such as a jet mill or a high-speed rotary pulverizer, it is classified into a desired particle size by a classifier such as an air classifier or an airflow classifier, and colored resin particles obtained by a pulverization method. Get.
- the binder resin used in the pulverization method, the colorant, and other additives such as a charge control agent and a release agent that are added as necessary are those mentioned in the above (A) suspension polymerization method.
- the colored resin particles obtained by the pulverization method can be made into core-shell type colored resin particles by a method such as an in situ polymerization method, similarly to the colored resin particles obtained by the suspension polymerization method (A) described above.
- binder resin other resins that have been widely used for toners can be used.
- specific examples of the binder resin used in the pulverization method include polystyrene, styrene-butyl acrylate copolymer, polyester resin, and epoxy resin.
- Colored resin particles are obtained by a production method such as the above-described (A) suspension polymerization method or (B) pulverization method.
- A) suspension polymerization method or (B) pulverization method the colored resin particles constituting the toner will be described.
- the colored resin particles described below include both core-shell type and non-core type.
- the volume average particle diameter (Dv) of the colored resin particles is preferably 4 to 12 ⁇ m, more preferably 5 to 10 ⁇ m.
- Dv volume average particle diameter
- the volume average particle diameter (Dv) of the colored resin particles is preferably 4 to 12 ⁇ m, more preferably 5 to 10 ⁇ m.
- Dv is less than 4 ⁇ m, the fluidity of the toner is lowered, the transferability may be deteriorated, and the image density may be lowered.
- Dv exceeds 12 ⁇ m the resolution of the image may decrease.
- the ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of the colored resin particles is preferably 1.0 to 1.3, and more preferably 1. 0 to 1.2. If Dv / Dn exceeds 1.3, transferability, image density, and resolution may decrease.
- the volume average particle diameter and the number average particle diameter of the colored resin particles can be measured using, for example, a particle size analyzer (trade name “Multisizer” manufactured by Beckman Coulter).
- the average circularity of the colored resin particles of the present invention is preferably 0.96 to 1.00, more preferably 0.97 to 1.00, and more preferably 0.98 to 1.00 from the viewpoint of image reproducibility. More preferably, it is 1.00.
- the average circularity of the colored resin particles is less than 0.96, the fine line reproducibility of printing may be deteriorated.
- the circularity is defined as a value obtained by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the projected image of the particle.
- the average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles, and is an index indicating the degree of unevenness of the colored resin particles.
- the average circularity is determined by the colored resin particles. 1 is shown in the case of a perfect sphere, and the value becomes smaller as the surface shape of the colored resin particles becomes more complicated.
- the colored resin particles preferably exhibit positive chargeability.
- Core-shell type composite fine particles (hereinafter sometimes simply referred to as “composite fine particles”) used as an external additive in the present invention are easily obtained by using resin fine particles as core particles.
- the diameter can be controlled, and furthermore, the true specific gravity can be controlled low because it can be prepared without firing by coating with an inorganic oxide by a sol-gel method, which is a preferred method described later. Further, since the core particles are resin fine particles, the core particles are relatively soft and damage to the photoreceptor is reduced.
- a core-shell type composite in which the surface of resin fine particles used in the present invention is coated with at least one inorganic component selected from the group consisting of silica, alumina, titania and zirconia (hereinafter sometimes referred to as inorganic component).
- the fine particles may be i) a commercially available product, or ii) a commercially available resin fine particle coated with the above inorganic component, or iii) a resin fine particle produced by polymerization, and the above inorganic component You may use what coat
- the inorganic component is preferably one component selected from the group consisting of silica, alumina, titania, and zirconia.
- the synthesis method of ii) is the same as the method of iii) except that the resin fine particles are synthesized by a polymerization reaction in the method of iii). Therefore, the method iii) will be specifically described below.
- the resin fine particles can be obtained by pulverizing a polymerized monomer synthesized by bulk polymerization, or a polymer obtained by polymerizing a polymerizable monomer by solution polymerization and polymerizing the resulting solution. It can also be obtained by adding to a poor solvent, or it can be obtained by polymerizing a polymerizable monomer by emulsion polymerization.
- the number average particle size of the core-shell type composite fine particles is preferably in the range of 30 to 300 nm. Since composite fine particles in the range are easily obtained, it is preferable to obtain resin fine particles by emulsion polymerization.
- emulsion polymerization conventionally known emulsion polymerization methods can be employed.
- polymerization auxiliary materials such as emulsifiers, polymerization initiators, molecular weight modifiers and the like used in normal polymerization can be used.
- Examples of the resin used for the resin fine particles to be coated with an inorganic component such as silica in the present invention include polymers obtained by homopolymerizing or copolymerizing polymerizable monomers exemplified below.
- Examples of the polymerizable monomer include a monovinyl monomer and a crosslinkable polymerizable monomer.
- Monovinyl monomers include styrene and derivatives thereof such as styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene; ethylene, propylene, butylene Ethylenically unsaturated monoolefins such as vinyl and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl iodide; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid-n-octyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid dimethyl
- crosslinkable polymerizable monomer examples include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; carboxylic acids having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate.
- aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof
- carboxylic acids having two or more hydroxyl groups such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate.
- An ester compound in which two or more acids are ester-bonded other divinyl compounds such as N, N-divinylaniline and divinyl ether;
- These monomers can be used alone or in combination of two or more. Among these, it is preferable to use a combination of a monovinyl monomer and a crosslinkable polymerizable monomer. By combining these, crosslinked resin fine particles can be obtained.
- a monovinyl monomers styrene and its derivatives and (meth) acrylic acid esters are more preferable, styrene and its derivatives are more preferable, and styrene is particularly preferable.
- the crosslinkable polymerizable monomer an aromatic divinyl compound and an ester compound in which two or more (meth) acrylic acids are ester-bonded to an alcohol having two or more hydroxyl groups are more preferable, and an aromatic divinyl compound is more preferable.
- Divinylbenzene is particularly preferred.
- the proportion of the monovinyl monomer and the crosslinkable monomer that is preferably used is such that the proportion of the crosslinkable monomer in the total monomers is preferably 0.1 to 20% by mass, and 0.3 to 10%. More preferably, it is more preferably 0.5% to 5% by weight.
- the emulsifier used in the emulsion polymerization of latex is not limited to a specific emulsifier.
- Specific examples of the emulsifier include anionic emulsifiers such as alkyl benzene sulfonates, aliphatic sulfonates, sulfate esters of higher alcohols; polyethylene glycol alkyl ether type, polyethylene glycol alkyl ester type, polyethylene glycol alkyl phenyl ether type, etc.
- the amount of the emulsifier is usually 0.05 to 5 parts by mass, preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the total amount of monomers used for the emulsion polymerization.
- the polymerization initiator used in latex emulsion polymerization is not limited to a specific polymerization initiator.
- Specific examples of the polymerization initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthane hydro Peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t- Organic peroxides such as butyl peroxyisobutyrate; azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbon
- a preferred polymerization initiator is an inorganic peroxide. These polymerization initiators can be used alone or in combination of two or more. Redox polymerization initiators in which these polymerization initiators are combined with a reducing agent such as sodium sulfite can also be used.
- the amount of the polymerization initiator used is usually 0.1 to 5 parts by mass, preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the total amount of monomers used for the emulsion polymerization.
- the addition method of the polymerization initiator in each stage may be batch addition, continuous addition, or divided addition.
- auxiliary materials such as a molecular weight regulator, a dispersant, a chelating agent and the like that are usually used in emulsion polymerization can be added.
- the type and amount of the secondary material are not limited.
- the addition timing and addition method of the auxiliary material to be used are not limited as necessary.
- molecular weight modifiers include: ⁇ -methylstyrene dimer; mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan, octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, methylene bromide; tetraethylthiuram Sulfur-containing compounds such as disulfide, dipentamethylene thiuram disulfide and diisopropylxanthogen disulfide. These molecular weight modifiers can be used alone or in combination of two or more.
- the polymerization temperature during latex emulsion polymerization is not limited to a specific range.
- the polymerization temperature is usually 5 to 95 ° C., preferably 50 to 95 ° C.
- the polymerization temperature at each stage may be different, or the polymerization temperature during the emulsion polymerization at each stage may be changed.
- the number average particle diameter of the resin fine particles is preferably 10 to 300 nm, more preferably 20 to 200 nm. This is because the number average particle diameter of the composite fine particles described later is preferably 30 to 300 nm.
- the method of covering the resin fine particles with the continuous layer of silica in the present invention can be achieved by using a silica coating technique using a sol-gel method.
- the silica coating by the sol-gel method is performed by the following method. After dispersing fine resin particles as a base in water and / or an aqueous medium in which silane alkoxide is dissolved, the dispersion is dropped into water and / or an aqueous medium to which alkali is added, or Water or an aqueous medium to which alkali has been added is added dropwise to the dispersion solution.
- the silane alkoxide dissolved in the dispersion containing the fine resin particles undergoes hydrolysis and polycondensation in the presence of alkali, and gradually insolubilizes. It is deposited on the surface of the resin fine particles due to the interaction. As a result, a coating layer is formed on the surface of the resin fine particles by adhering the granular lumps containing silica.
- the base resin fine particles are dispersed in water and / or an aqueous medium in which silane alkoxide is dissolved, and then stirred. If necessary, the resin fine particles may be dispersed in a medium in which the silane alkoxide is dissolved by applying heat.
- the resin fine particles used for producing the core-shell type composite fine particles having the surface of the resin fine particles coated with silica are preferably produced by an emulsion polymerization method as described above, followed by silica.
- the coating by may be performed by washing the resin fine particles, filtering and drying, dispersing the dried resin fine particles in a solvent, and using the sol-gel method. Preferably it is done.
- silane alkoxide used above examples include the following.
- examples of the bifunctional or higher alkoxide include tetramethoxysilane, methyltriethoxysilane, hexyltriethoxysilane, triethoxychlorosilane, di-t-butoxydiacetoxysilane, hydroxymethyltriethoxysilane, tetraethoxysilane, and tetra-n.
- tetrafunctional silane alkoxides such as tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, and tetrakis (2-methacryloxyethoxysilyl) silane are preferably used as essential components.
- Examples of monofunctional silane alkoxides that can be used in combination with the above bifunctional or higher silane alkoxides include (3-acryloxypropyl) dimethylmethoxysilane, o-acryloxy (polyethyleneoxy) trimethylsilane, acrylic Loxytrimethylsilane, 1,3-bis (methacryloxy) -2-trimethylsiloxypropane-3-chloro-2-trimethylsiloxypropene, (cyclohexenyloxy) trimethylsilane, methacryloxyethoxytrimethylsilane, (methacryloxymethyl) dimethylethoxy Silane etc. are mentioned. These silane alkoxides may be used alone or in combination of two or more.
- a coating technique using a sol-gel method may be used as a suitable method for covering the resin fine particles in the present invention with a continuous layer of an inorganic component such as alumina.
- a coating technique using a sol-gel method may be used.
- the titania coating by the sol-gel method will be described as an example.
- the titanium alkoxide dissolved in the dispersion containing the resin fine particles undergoes hydrolysis and polycondensation in the presence of alkali and gradually insolubilizes. It is deposited on the surface of the resin fine particles due to the interaction. As a result, a coating layer is formed on the surface of the resin fine particles by adhering the granular mass containing titania to each other.
- the resin fine particles as a base material are dispersed in water and / or an aqueous medium in which titanium alkoxide is dissolved, and then stirred. If necessary, it is preferable to disperse resin fine particles in a medium in which titanium alkoxide is dissolved by applying heat.
- titanium alkoxide used above examples include the following.
- examples of the bifunctional or higher functional titanium alkoxide include tetramethoxy titanium, tetraethoxy titanium, tetra n-propoxy titanium, tetra i-propoxy titanium, tetra n-butoxy titanium, tetra i-butoxy titanium, tetra s-butoxy.
- examples include titanium, tetra-t-butoxy titanium, tetra-n-pentoxy titanium, tetra-n-hexyloxy titanium, and the like.
- resin fine particles can be suitably covered with a continuous layer of alumina by alumina coating by a sol-gel method.
- the aluminum alkoxide that can be used in the sol-gel method include the following.
- the bifunctional or higher functional aluminum alkoxide include, for example, trimethoxyaluminum, triethoxyaluminum, tri-n-propoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, tri-i-butoxyaluminum, tris-butoxyaluminum , Tri-t-butoxyaluminum, tri-n-pentoxyaluminum, tri-n-hexyloxyaluminum and the like.
- the resin fine particles can be suitably covered with a continuous layer of zirconia by zirconia coating by a sol-gel method.
- zirconium alkoxide that can be used in the sol-gel method include the following.
- the bifunctional or higher functional zirconium alkoxide include tetramethoxy zirconium, tetraethoxy zirconium, tetra n-propoxy zirconium, tetra n-butoxy zirconium and the like.
- Silica, alumina, titania, and zirconia may each be coated with resin fine particles, or a mixture of two or more inorganic components may be coated with resin fine particles.
- aqueous medium used in the sol-gel reaction for example, alcohols such as methanol, ethanol, and isopropanol are used.
- alcohols such as methanol, ethanol, and isopropanol are used.
- the solubility of the polycondensate of the alkoxide that is an inorganic component increases, and the resin The polycondensate becomes difficult to deposit on the surface of the fine particles. Therefore, it is preferable to use methanol or ethanol as the aqueous medium.
- the surface of the core-shell type composite fine particles is subjected to a hydrophobization treatment so that the core-shell type composite fine particles prepared by the above method have a stable effect even under high temperature and high humidity.
- a hydrophobic treatment agent either a positively chargeable treatment agent or a negatively chargeable treatment agent can be used.
- a hydrophobizing agent for example, a silane coupling agent, silicone oil, or the like can be used.
- silane coupling agent examples include disilazane such as hexamethyldisilazane; cyclic silazane; trimethylsilane; trimethylchlorosilane; dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, and methyltrimethoxysilane.
- Methyltriethoxysilane isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxy Alkylsilane compounds such as silane, ⁇ -methacryloxypropyltrimethoxysilane, and vinyltriacetoxysilane, and ⁇ - Aminopropyltriethoxysilane, ⁇ - (2-aminoethyl) aminopropyltrimethoxysilane, ⁇ - (2-aminoethyl) aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- (2 -Aminoethyl
- silicone oil examples include dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, and amino-modified silicone oil. These can be used alone or in combination of two or more.
- the hydrophobizing agent may be contained alone or in combination of two or more, and when a silane coupling agent or silicone oil is used, the resulting toner is more preferable because it provides high image quality. .
- a general method can be used, and examples thereof include a wet method and a dry method.
- the dry method represented by the method of dripping or spraying the hydrophobic treatment agent while stirring the core-shell composite fine particles used as an external additive at high speed, and dissolving the hydrophobic treatment agent in an organic solvent
- a wet method represented by a method of adding core-shell type composite fine particles while stirring an organic solvent containing a hydrophobizing agent may be used.
- the wet method is preferable because the core-shell composite fine particles can be uniformly hydrophobized.
- the reaction liquid obtained by adding an organic solvent containing a hydrophobizing agent is used as it is while stirring the reaction liquid of the core-shell composite fine particles obtained by the sol-gel reaction.
- Hydrophobic treatment can be performed by adding a reaction solution of core-shell type composite fine particles obtained by sol-gel reaction while stirring an organic solvent containing a hydrophobization treatment agent. You can also.
- the core-shell type composite fine particles obtained by the sol-gel reaction are washed, filtered, and dried, and then the core-shell type composite fine particles are dispersed in an organic solvent and the hydrophobization treatment agent is contacted. Is preferred. Hydrophobized core-shell composite fine particles dispersed in an organic solvent, obtained by this preferred method, are used after removing the organic solvent by distillation under reduced pressure, drying and crushing as necessary.
- Core-shell type composite fine particles Core-shell type composite fine particles are obtained by the above-described production method. Hereinafter, the core-shell type composite fine particles used as the external additive of the present invention will be described.
- the core-shell type composite fine particles used as an external additive in the present invention are core-shell type composite fine particles in which the surface of the resin fine particles is coated with an inorganic component.
- the numerical range of the volume ratio of the silica component when the inorganic component is silica will be described.
- the volume ratio of the silica component of the composite fine particles is 45 to 75% by volume.
- the volume ratio is less than 45% by volume, the fluidity of the toner, which will be described later, may be reduced.
- the volume ratio of the silica component of the composite fine particles is more preferably 50 to 70% by volume, and further preferably 55 to 65% by volume.
- the volume ratio of these inorganic components when the inorganic component is alumina, titania, or zirconia will be described.
- the volume ratio of the inorganic component of the composite fine particles is preferably 25 to 75% by volume.
- the volume ratio is less than 25% by volume, the amount of metal oxide decreases, and thus there is a possibility that the effect of suppressing the increase in charge in a low-temperature, low-humidity (L / L) environment may not be exhibited.
- the volume ratio of the inorganic component of the composite fine particles is more preferably 30 to 70% by volume, still more preferably 45 to 70% by volume, It is particularly preferably 50 to 70% by volume.
- the inorganic component contains two or more inorganic components selected from the group consisting of silica, alumina, titania, and zirconia
- the inorganic component of the composite fine particles when the total volume of the core-shell composite fine particles is 100% by volume
- the total volume ratio is preferably 45 to 75% by volume, more preferably 50 to 70% by volume, and still more preferably 55 to 70% by volume.
- the volume ratio of the inorganic component of the core-shell type composite fine particles is the ratio of the volume of the coated silica, alumina, titania and / or zirconia to the total volume of the core-shell type fine composite particles.
- the ratio is the ratio of the increase in the volume of the resin fine particles as the raw material to the volume of the core-shell composite fine particles with respect to the total volume of the core-shell composite fine particles, and the number average particle diameter of the resin fine particles and the core-shell composite fine particles It can be calculated from the number average particle diameter of
- the following method can be employed. First, using atomic absorption spectrometry or the like, it is confirmed whether or not the fine particles contain silicon, aluminum, titanium and / or zirconium. When it is found that the fine particles contain silicon, aluminum, titanium and / or zirconium, the number average particle diameter of the fine particles is measured in the same manner as described above. Subsequently, the fine particles are put into hydrofluoric acid to dissolve silica, alumina, titania and / or zirconia, washed with water and dried, and the number average of resin fine particles which are cores as described above Measure the particle size. From the two values of the number average particle diameter before and after dissolution of the inorganic component measured in this manner, the volume ratio of the inorganic component of the fine particles can be calculated.
- the adsorbed moisture content of the core-shell composite fine particles is preferably 0.5 to 2.5% by mass.
- the adsorbed moisture content of the core-shell type composite fine particles is more preferably 0.5 to 2.0% by mass, and still more preferably 0.8 to 1.5% by mass.
- the amount of adsorbed moisture is determined by using a moisture absorption / desorption measuring device (IGAsorp, manufactured by Nippon Shibel Hegner) for 1 hour in a dry nitrogen stream, and then in air at 32 ° C. and 80% humidity. Then, moisture was adsorbed for 1 hour, and the mass of the sample adsorbed with moisture was measured. From the measurement results, (increased mass / sample mass) ⁇ 100 was defined as the amount of adsorbed moisture (mass%).
- IGAsorp moisture absorption / desorption measuring device
- the core-shell type composite fine particles exhibit positive chargeability.
- the value of the blow-off charge amount of the core-shell type composite fine particles is preferably +1000 to +4000 ⁇ C / g.
- the value is less than +1000 ⁇ C / g, the charge amount of the toner may be reduced and fog may be easily generated.
- the value exceeds +4000 ⁇ C / g, it is difficult to prepare the core-shell composite fine particles.
- the value of the blow-off charge amount of the core-shell type composite fine particle is more preferably +1500 to +3000 ⁇ C / g, and further preferably +1700 to +2500 ⁇ C / g.
- the number average particle size of the core-shell type composite fine particles is preferably 30 to 300 nm. When the number average particle diameter is less than 30 nm, the charge amount of the toner may be reduced and fog may be easily generated. On the other hand, when the number average particle diameter exceeds 300 nm, the environmental stability of the toner described later may be deteriorated, and the fogging of the toner in a high temperature and high humidity environment may be deteriorated.
- the number average particle size of the core-shell type composite fine particles is more preferably 40 to 250 nm, and further preferably 50 to 200 nm.
- the toner of the present invention is prepared by mixing and stirring the colored resin particles together with the core-shell composite fine particles, and suitably attaching and externally adding the core-shell composite fine particles to the surface of the colored resin particles. Can be obtained.
- the addition amount of the core-shell type composite fine particles is preferably 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles.
- the addition amount of the core-shell type composite fine particles is less than 0.1 parts by mass with respect to 100 parts by mass of the colored resin particles, the effect of the present invention is not sufficiently exhibited.
- the addition amount of the core-shell type composite fine particles exceeds 2.0 parts by mass with respect to 100 parts by mass of the colored resin particles, the charge amount of the toner may be lowered.
- the addition amount of the core-shell type composite fine particles is preferably 0.15 to 1.0 part by mass, more preferably 0.2 to 0.8 part by mass with respect to 100 parts by mass of the colored resin particles.
- the method for adhering and adding (external addition) the core-shell type composite fine particles to the surface of the colored resin particles is not particularly limited.
- a high-speed stirrer an FM mixer (trade name, manufactured by Mitsui Mining), a super mixer (trade name) , Kawada Seisakusho Co., Ltd.), Q mixer (: trade name, manufactured by Mitsui Mining Co., Ltd.), Mechano Fusion System (: trade name, manufactured by Hosokawa Micron Co., Ltd.) Can be performed using an apparatus capable of.
- Other external additives may be mixed with the core-shell type composite fine particles.
- the other external additives include inorganic fine particles made of silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, calcium carbonate, calcium phosphate, and / or cerium oxide; polymethyl methacrylate resin, silicone resin, and And / or organic fine particles comprising melamine resin and the like.
- inorganic fine particles are preferable, and among inorganic fine particles, silica and / or titanium oxide are preferable, and fine particles made of silica are particularly preferable.
- the said other external additive used together with a core-shell type composite microparticle may be only one type, and may be two or more types.
- the amount of other external additives added is preferably 0.1 to 6 parts by weight, more preferably 0.3 to 5 parts by weight, and still more preferably 0.5 to 4 parts by weight.
- the number average particle diameter of the other external additive is preferably 7 to 300 nm.
- the number average particle diameter of the other external additive is less than 7 nm, the other external additive is easily embedded from the surface of the colored resin particles to the inside, and the fluidity is sufficiently sufficient for the toner particles. In some cases, it cannot be applied, and the printing performance may be adversely affected.
- the number average particle diameter of the other external additive exceeds 300 nm, the ratio (coverage) of the other external additive to the surface of the toner particles decreases, so that the fluidity May not be sufficiently imparted to the toner particles, which may adversely affect printing performance.
- the number average particle diameter of the other external additive is more preferably 15 to 80 nm.
- Toner of the present invention The first toner of the present invention obtained through the above-mentioned process is a stable charging with time by using core-shell type composite particles in which the surface of resin particles is coated with silica as an external additive. Therefore, even when a large number of sheets are continuously printed, the image quality is hardly deteriorated due to fog or the like, and the toner for developing an electrostatic image has excellent fluidity.
- the second toner of the present invention obtained through the above steps uses core-shell composite fine particles in which the surface of resin fine particles is coated with alumina, titania and / or zirconia as an external additive.
- the toner of the present invention preferably has a fluidity value of 80 to 100 as measured by the method described below.
- the fluidity as used herein is a value expressed as a percentage of the ratio of the toner passing through the sieve to the total mass of the toner.
- the toner of the present invention preferably has a fluidity value of 82 to 100, and more preferably 85 to 100.
- a sieve having a predetermined amount of openings is prepared.
- two or more types of sieves may be used.
- the sieves are overlapped from the top in the descending order of openings.
- a predetermined amount of the toner sample to be measured is placed on the sieve.
- the toner sample is placed on the sieve that is stacked on top, that is, the sieve having the largest opening.
- the sieve is vibrated for a certain period of time under constant vibration conditions, and then the mass of the toner remaining on the sieve is measured.
- the fluidity value is a value that is calculated based on the ratio and expresses the ratio of the toner that has passed through the sieve to the total mass of the toner as a percentage.
- the ratios are added together to calculate the fluidity value. In this case, a coefficient of 1 or less may be assigned to each sieve, and the product of the ratio of the mass of toner remaining on the sieve and the coefficient may be added up.
- Example Series I> I-1 Production of core-shell type composite fine particles
- a container equipped with a stirrer substituted with nitrogen 3 parts of soft dodecylbenzenesulfonic acid was dissolved in 150 parts of ion-exchanged water, and then 95 parts of styrene was emulsified to prepare a polymerizable monomer emulsion. After raising the temperature of the emulsion to 80 ° C., 0.6 part of potassium persulfate dissolved in 10 parts of ion exchange water was added and polymerized for 2 hours.
- the obtained particles were washed with ion-exchanged water, then washed with methanol, the particles were filtered, and dried at 45 ° C. for 24 hours under a reduced pressure of 40 kPa, whereby the surface of the resin fine particles was Core-shell type composite fine particles I-1 coated with silica were obtained.
- a part of the core-shell type composite fine particles I-1 was subjected to measurement of the number average particle size of the core-shell type composite fine particles described later.
- this core-shell type composite fine particle I-1 is dispersed in 600 g of toluene, and 1 part of 3-aminopropyltriethoxysilane (a silicon compound containing an amino group) is added to 100 parts by mass of silica contained in the fine particle I-1. After the addition, the mixture was dispersed and mixed for 15 minutes and brought into contact with the fine particles. Next, 1 part of trifluoropropyltrimethoxysilane (a silicon compound containing no amino group) was added to the fine particles, and then dispersed and mixed for 15 minutes to contact the fine particles. The dispersion was distilled under reduced pressure, dried and crushed to obtain core-shell type composite fine particles IA that had been made hydrophobic to be positively charged. There was no change in particle size due to the hydrophobization treatment.
- Production Example I-7 1.0 part by mass of acrylic / styrene resin fine particles (manufactured by Soken Chemical Co., Ltd., trade name: MP-5500, number average particle size 400 nm) of Production Example I-6 was added to acrylic / styrene resin fine particles (Soken Chemical ( Co., Ltd., trade name: MP-1450, number average particle size 250 nm) Core-shell composite fine particles IG were produced in the same manner as in Production Example I-6 except that the content was changed to 1.0 part by mass. .
- Core-shell type composite fine particles IA to IG obtained from the above production examples I-1 to I-7, hydrophobized silica fine particles (trade name: H05TA, manufactured by Clariant) And silica fine particles IA), and hydrophobized silica fine particles (trade name: TG-C321, manufactured by Cabot Corporation.
- silica fine particles IB hydrophobized silica fine particles
- the number average particle diameter, the amount of adsorbed water, and the charge amount were measured.
- the core-shell type composite fine particles IA to IG the number average particle diameter of the resin fine particles as the raw material of these composite fine particles was also measured, and the ratio of the silica component of the core-shell type composite fine particles was calculated.
- the number average particle size of the core-shell type composite fine particles and the like and the resin fine particles as the raw material were measured by the following method. That is, for each of these fine particles, a field emission scanning electron microscope (manufactured by Hitachi, Ltd., product name: S-4700) is used to take a photograph at a magnification of 10,000 times, and the photograph is taken as an image processing analyzer.
- a field emission scanning electron microscope manufactured by Hitachi, Ltd., product name: S-4700
- core-shell type composite fine particles IA to IG and silica fine particles IA and IB the measurement results of adsorbed water amount, chargeability and charge amount are shown together with the structure data of each external additive particle. Shown in I-1.
- external additive (IA) refers to core-shell type composite fine particles IA to IG, and silica fine particles IA and IB.
- I-3 Production of colored resin particles and evaluation of physical properties I-3-1.
- the mixture was further dispersed uniformly using a media type dispersing machine.
- 5 parts of dipentaerythritol hexamyristate was added, mixed and dissolved as a release agent to obtain a polymerizable monomer composition.
- Post-treatment step The aqueous dispersion of the colored resin particles was added dropwise with stirring sulfuric acid at room temperature, and acid washing was performed until the pH was 6.5 or less. Subsequently, filtration separation was performed, 500 parts of ion-exchanged water was added to the obtained solid content to make a slurry again, and water washing treatment (washing, filtration, dehydration) was repeated several times. Next, filtration separation was performed, and the obtained solid content was put in a container of a dryer and dried at 45 ° C. for 48 hours to obtain dried colored resin particles.
- the obtained colored resin particles were measured for volume average particle diameter (Dv) and particle diameter distribution (Dv / Dn).
- Dv volume average particle diameter
- Dv / Dn particle diameter distribution
- the obtained colored resin particles had a volume average particle diameter (Dv) of 9.7 ⁇ m and a particle diameter distribution (Dv / Dn) of 1.14.
- the average circularity of the obtained colored resin particles was calculated. First, 10 mL of ion-exchanged water is put in a container in advance, and 0.2 mL of an alkylbenzene sulfonic acid aqueous solution (manufactured by Fujifilm, trade name: Drywell) is added as a dispersant therein, and 0.2 g of colored resin particles are further added. In addition, 60 W (Watt) was applied for 3 minutes with an ultrasonic disperser. The colored resin particle concentration at the time of measurement is adjusted to 3,000 to 10,000 particles / ⁇ L, and 1,000 to 10,000 colored resin particles having an equivalent circle diameter of 0.4 ⁇ m or more are flow-type particle images. Measurement was performed using an analyzer (trade name: FPIA-2100, manufactured by Simex Corporation). When the average circularity was determined from the measured value, the average circularity of the obtained colored resin particles was 0.987.
- Example I-1 To 100 parts of the colored resin particles, 1.2 parts of the core-shell type composite fine particles IA produced in Production Example I-1 above, and silica fine particles having a number average primary particle size of 22 nm that have been hydrophobized (manufactured by Cabot Corporation) , Trade name: TG-7120) was added, and the mixture was mixed and stirred for 5 minutes at a peripheral speed of 40 m / s using an FM mixer (trade name: FM-10, manufactured by Nippon Coke Co., Ltd.). The toner for electrostatic image development of Example I-1 was obtained.
- an FM mixer trade name: FM-10, manufactured by Nippon Coke Co., Ltd.
- Example I-2 Except that the core-shell composite fine particles IA produced in Production Example I-1 were changed to the core-shell composite fine particles IB produced in Production Example I-2, the same as Example I-1 The toner for developing an electrostatic charge image of Example I-2 was obtained.
- Example I-3 Except that the core-shell type composite fine particles IA produced in Production Example I-1 were changed to the core-shell type composite fine particles IC produced in Production Example I-3, the same as Example I-1 The toner for developing an electrostatic charge image of Example I-3 was obtained.
- Example I-4 Except that the core-shell composite fine particles IA produced in Production Example I-1 were changed to the core-shell composite fine particles ID produced in Production Example I-4, the same as Example I-1 The toner for developing an electrostatic charge image of Example I-4 was obtained.
- Example I-5 Except that the core-shell type composite fine particle IA produced in Production Example I-1 was changed to the core-shell type composite fine particle IE produced in Production Example I-5, the same as Example I-1 The toner for developing an electrostatic charge image of Example I-5 was obtained.
- Comparative Example I-1 For electrostatic image development of Comparative Example I-1, in the same manner as Example I-1, except that the core-shell type composite fine particles IA produced in Production Example I-1 were changed to Silica fine particles IA. A toner was obtained.
- Comparative Example I-2 For electrostatic image development of Comparative Example I-2 in the same manner as in Example I-1, except that the core-shell type composite fine particles IA produced in Production Example I-1 were changed to Silica fine particles IB. A toner was obtained.
- white solid printing (printing density 0%) is performed, the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the developed photosensitive member is adhesive tape (manufactured by Sumitomo 3M Ltd., product) Name: Scotch mending tape 810-3-18) and then peeled off and affixed to printing paper.
- the whiteness (B) of the printing paper to which the adhesive tape was applied was measured with a whiteness meter (Nippon Denshoku Co., Ltd., trade name: ND-1).
- the whiteness (A) was measured and the difference in whiteness (BA) was defined as the fog value (%). Smaller values indicate better fog and better.
- the toner of Comparative Example I-1 has a toner charge amount of 37 ⁇ C / g in a normal temperature and normal humidity (N / N) environment and a toner charge amount of 25 ⁇ C / g in a high temperature and high humidity (H / H) environment. Also showed a moderate amount of charge. Further, the toner of Comparative Example I-1 has a fog density of 0.2 in a normal temperature and normal humidity (N / N) environment and a fog generation number of 10,000 or more in a normal temperature and normal humidity (N / N) environment.
- the fluidity value of the toner of Comparative Example I-2 was 94, and there was no problem with fluidity. Further, in the toner of Comparative Example I-2, the fog density in a normal temperature and normal humidity (N / N) environment is 0.8, and the fog generation number in a normal temperature and normal humidity (N / N) environment exceeds 10,000 sheets. As a result, there was no problem in printing durability at least in a normal temperature and normal humidity (N / N) environment.
- the toner of Comparative Example I-2 has a toner charge amount of 18 ⁇ C / g in a normal temperature and normal humidity (N / N) environment and a toner charge amount of 14 ⁇ C / g in a high temperature and high humidity (H / H) environment.
- the toners of Examples I-1 to I-5 and Comparative Examples I-1 to I-4 the lowest charge amount was shown.
- the fog density of the toner of Comparative Example I-2 in a high-temperature and high-humidity (H / H) environment is 12, which is 5 times higher than the results of Examples I-1 to I-5 described later. It can be seen that fog occurs.
- the toner of Comparative Example I-3 has a toner charge amount of 30 ⁇ C / g in a normal temperature and normal humidity (N / N) environment, and a toner charge amount of 20 ⁇ C / g in a high temperature and high humidity (H / H) environment. Also showed a moderate amount of charge.
- the fluidity value of the toner of Comparative Example I-3 was 69, and the poorest fluidity was exhibited among the toners of Examples I-1 to I-5 and Comparative Examples I-1 to I-4. .
- the fog density of the toner of Comparative Example I-3 in a normal temperature and normal humidity (N / N) environment is 2.8.
- the normal temperature normal temperature It can be seen that fog of 4 times or more occurs in a wet (N / N) environment. Further, the fog density of the toner of Comparative Example I-3 in a high temperature and high humidity (H / H) environment is 25. Compared with the results of Examples I-1 to I-5 described later, the high temperature and high humidity ( It can be seen that fog of 10 times or more occurs in the H / H) environment.
- the toner of Comparative Example I-3 using the core-shell type composite fine particles in which the volume ratio of the silica component is lower than that of the composite fine particles used in the present invention is excellent in fluidity, normal temperature and normal humidity (N / N It can be seen that the printing durability is inferior in the environment and in a high temperature and high humidity (H / H) environment.
- the toner of Comparative Example I-4 had a fluidity value of 78, which was slightly inferior in fluidity.
- the toner of Comparative Example I-4 has a toner charge amount of 20 ⁇ C / g in a normal temperature and normal humidity (N / N) environment, and a toner charge amount of 15 ⁇ C / g in a high temperature and high humidity (H / H) environment. As compared with toners of Examples I-1 to I-5, which will be described later, a lower charge amount was exhibited.
- the fog density of the toner of Comparative Example I-4 in a normal temperature and normal humidity (N / N) environment is 3.0, which is higher than that of Examples I-1 to I-5 described later. It can be seen that fog of 4 times or more occurs in a wet (N / N) environment. Further, the fog density of the toner of Comparative Example I-4 in a high-temperature and high-humidity (H / H) environment is 22, and compared with the results of Examples I-1 to I-5 described later, It can be seen that fog of 9 times or more occurs in the H / H) environment.
- the toner of Comparative Example I-4 using the core-shell type composite fine particles in which the volume ratio of the silica component is extremely lower than the composite fine particles used in the present invention is in a normal temperature and normal humidity (N / N) environment.
- the amount of charge in a high-temperature and high-humidity (H / H) environment is low, the fluidity, and the printing durability under a normal temperature and normal humidity (N / N) environment and a high-temperature and high-humidity (H / H) environment may be inferior. I understand.
- the toners of Examples I-1 to I-5 all have a fluidity of 86 or more and are in a normal temperature and normal humidity (N / N) environment.
- the toner charge amount is 25 ⁇ C / g or more
- the toner charge amount in a high temperature and high humidity (H / H) environment is 21 ⁇ C / g or more
- the fog density in a normal temperature and normal humidity (N / N) environment Is 0.8 or less
- the fog density in a high temperature and high humidity (H / H) environment is 2.5 or less
- the number of fog occurrences in a normal temperature and normal humidity (N / N) environment is 7, The result was more than 000.
- the surface of the resin fine particle is a core-shell type composite fine particle coated with silica and the total volume of the composite fine particle is 100% by volume
- the volume ratio of the silica component of the composite fine particle is 45 to 75 volume. %
- the toners of Examples I-1 to I-5 containing the core-shell type composite fine particles as an external additive have excellent fluidity and chargeability, and even after continuous printing of a large number of sheets, It can be seen that the image quality is not easily degraded due to the above.
- Example Series II> II-1 Production of core-shell composite fine particles
- Production Example II-1 In a container equipped with a stirrer substituted with nitrogen, 3 parts of soft dodecylbenzenesulfonic acid was dissolved in 150 parts of ion-exchanged water, and then 95 parts of styrene was emulsified to prepare a polymerizable monomer emulsion. After raising the temperature of the emulsion to 80 ° C., 0.6 part of potassium persulfate dissolved in 10 parts of ion exchange water was added and polymerized for 2 hours.
- the obtained fine particles were washed with ion-exchanged water, then washed with methanol, the fine particles were filtered off, and then dried at 45 ° C. for 24 hours under a reduced pressure of 40 kPa.
- Core-shell type composite fine particles II-1 coated with titania were obtained. A part of the core-shell type composite fine particles II-1 was subjected to measurement of the number average particle diameter of the core-shell type composite fine particles described later.
- this core-shell type composite fine particle II-1 was dispersed in 600 g of toluene, and 1 part of 3-aminopropyltriethoxysilane (a silicon compound containing an amino group) was added to 100 parts of the fine particle II-1. The mixture was dispersed and mixed for 15 minutes and brought into contact with the fine particles. Next, 1 part of hexamethyldisilazane (a silicon compound containing no amino group) was added to the fine particles, and then dispersed and mixed for 15 minutes to contact the fine particles. The dispersion was distilled under reduced pressure and dried, and then the fine particles were crushed to obtain core-shell type composite fine particles II-A that were hydrophobized to be positively charged. There was no change in particle size due to the hydrophobization treatment.
- 3-aminopropyltriethoxysilane a silicon compound containing an amino group
- Production Example II-4 In Production Example II-1 above, the polymerizable monomer used in the initial polymerization was changed from 95 parts of styrene and 5 parts of divinylbenzene to 100 parts of styrene, and 5 parts of divinylbenzene added later was not used.
- Produced core-shell composite fine particles II-D in the same manner as in Production Example II-1.
- the core-shell composite fine particles II-A to II-F obtained from the above Production Examples II-1 to II-6 were measured for number average particle diameter and adsorbed water content.
- the number average particle size of the resin fine particles as the raw material of the core-shell type composite fine particles II-A to II-F was also measured, and the ratio of the inorganic components of the core-shell type composite fine particles was calculated.
- the number average particle size of the core-shell type composite fine particles and the resin fine particles as the raw material were measured by the following method. That is, each of these fine particles was observed using a field emission scanning electron microscope (manufactured by Hitachi, Ltd., model S-4500). The particle diameter was measured so that the cumulative number was 300 or more, and the number average particle diameter was calculated.
- Example II-1 To 100 parts of the colored resin particles, 0.5 part of core-shell type composite fine particles II-A produced in Production Example II-1 above, 0.8 part of TG-7120 (manufactured by Cabot Corporation), NA50Y (manufactured by Nippon Aerosil Co., Ltd.) 1.0 part), mixed and stirred using an FM mixer (trade name: FM-10, manufactured by Nippon Coke Co., Ltd.), externally added, and the toner for developing an electrostatic charge image of Example II-1 Got. The peripheral speed of the stirring blade at this time was 40 m / s, and the stirring time was 5 minutes.
- Example II-2 Except that the core-shell type composite fine particle II-A produced in Production Example II-1 was changed to the core-shell type composite fine particle II-B produced in Production Example II-2, the same as Example II-1 The toner for developing an electrostatic charge image of Example II-2 was obtained.
- Example II-3 Except that the core-shell type composite fine particle II-A produced in Production Example II-1 was changed to the core-shell type composite fine particle II-C produced in Production Example II-3, the same as Example II-1 The toner for developing an electrostatic charge image of Example II-3 was obtained.
- Example II-4 Except that the core-shell type composite fine particle II-A produced in Production Example II-1 was changed to the core-shell type composite fine particle II-D produced in Production Example II-4, the same as Example II-1 The toner for developing an electrostatic charge image of Example II-4 was obtained.
- Example II-5 Except that the core-shell composite fine particle II-A produced in Production Example II-1 was changed to the core-shell composite fine particle II-E produced in Production Example II-5, the same as Example II-1 The toner for developing an electrostatic charge image of Example II-5 was obtained.
- Example II-6 Except that the core-shell type composite fine particle II-A produced in Production Example II-1 was changed to the core-shell type composite fine particle II-F produced in Production Example II-6, the same as Example II-1 The toner for developing an electrostatic charge image of Example II-6 was obtained.
- Comparative Example II-1 A toner for developing an electrostatic charge image of Comparative Example II-1 was obtained in the same manner as in Example II-1, except that the core-shell type composite fine particle II-A produced in Production Example II-1 was not used.
- the full width at half maximum of the maximum concentration in a low temperature and low humidity (L / L) environment is defined as the line width, and the difference between the line width and the reference line width is 10 ⁇ m or less is one sheet. Evaluated as ⁇ for reproducing the line image of the eye. A case where the difference in the line width can be maintained at 10 ⁇ m or more and 20 ⁇ m or less is evaluated as ⁇ . Those exceeding 20 ⁇ m are evaluated as x.
- Printing durability test under normal temperature and humidity (N / N) environment For the printing durability test, a commercially available non-magnetic one-component printer (HL-3040CN) is used, and the toner cartridge of the developing device is filled with toner. After that, the printing paper was set. After standing for 24 hours in a normal temperature and normal humidity (N / N) environment (temperature: 23 ° C., humidity: 50%), continuous printing was performed up to 10,000 sheets at a 5% print density in the same environment. . Black solid printing (printing density 100%) was performed every 500 sheets, and the printing density of the black solid image was measured using a reflective image densitometer (trade name: RD918, manufactured by Macbeth).
- white solid printing (printing density 0%) is performed, the printer is stopped in the middle of white solid printing, and the toner in the non-image area on the developed photosensitive member is adhesive tape (manufactured by Sumitomo 3M Ltd., product) Name: Scotch mending tape 810-3-18) and then peeled off and affixed to printing paper.
- the whiteness (B) of the printing paper to which the adhesive tape was applied was measured with a whiteness meter (Nippon Denshoku Co., Ltd., trade name: ND-1).
- the whiteness (A) was measured and the difference in whiteness (BA) was defined as the fog value (%). Smaller values indicate better fog and better.
- Table II-2 shows the measurement and evaluation results of the electrostatic image developing toners of Examples II-1 to II-6 and Comparative Example II-1 together with the toner compositions.
- the toner of Comparative Example II-1 has a fog density of 0.7 in a normal temperature and normal humidity (N / N) environment, and the number of fog occurrences in a normal temperature and normal humidity (N / N) environment exceeds 10,000.
- N / N normal temperature and normal humidity
- the fog density in the high-temperature and high-humidity (H / H) environment of the toner of Comparative Example II-1 is 3.2.
- the results are shown in Examples II-1 to II-6 and Comparative Example II-1. Among the toners, the fog density is the highest.
- the toners of Examples II-1 to II-6 all have a fog density of 0.8 or less in a normal temperature and normal humidity (N / N) environment, and high temperatures and high temperatures.
- the fog density in a humid (H / H) environment is 2.6 or less, and the number of fog occurrences in a normal temperature and normal humidity (N / N) environment exceeds 7,000, and low temperature and low humidity.
- the evaluation of fine line reproducibility under (L / L) environment is ⁇ or more. Therefore, the toners of Examples II-1 to II-6 containing the core-shell type composite fine particles whose surface of the resin fine particles are coated with an inorganic component as an external additive have impaired fine line reproducibility even in a low temperature and low humidity environment.
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Abstract
Description
また、現像に用いるトナー粒子の表面には、トナーの帯電安定性、流動性、及び耐久性等を向上させる目的として、一般に着色樹脂粒子(トナー粒子)よりも粒径の小さい無機微粒子や有機微粒子等の外添剤が外添(付着添加)されている。
特許文献1には、外添剤として、有機微粒子の表面に無機微粒子が固着した無機/有機複合微粒子を用いたトナーが開示されている。特許文献2には、外添剤として、表面がシリカの連続層で覆われており、特定の平均粒径を有する樹脂微粒子を含むトナーが開示されている。
本発明の第2の目的は、高温高湿環境下におけるカブリの発生を抑制し、低温低湿環境下における細線再現性に優れた静電荷像現像用トナーを提供することにある。
また、上記の如き本発明の静電荷像現像用トナーによれば、外添剤として、樹脂微粒子の表面が、アルミナ、チタニア及び/又はジルコニアで被覆されているコアシェル型複合微粒子を使用することにより、低温低湿環境下におけるトナー帯電量の上昇が抑制され、同環境下においても細線再現性が損なわれることなく安定した印字が行え、且つ、帯電量の上昇により発生する印字不具合などがなく、良好な画質が得られる静電荷像現像用トナーが提供される。
本発明のトナーは、結着樹脂及び着色剤を含有する着色樹脂粒子と、外添剤として樹脂微粒子の表面がシリカ、アルミナ、チタニア及び/又はジルコニアで被覆されているコアシェル型複合微粒子を含有する。
本発明のトナーは、前記着色樹脂粒子の表面に、外添剤として前記コアシェル型複合微粒子を付着添加することにより得られるものであることが好ましい。
以下、本発明に使用される着色樹脂粒子の製造方法、当該製造方法により得られる着色樹脂粒子、本発明に外添剤として使用されるコアシェル型複合微粒子の製造方法、当該製造方法により得られるコアシェル型複合微粒子、当該着色樹脂粒子及び外添剤を用いた本発明のトナーの製造方法及び本発明のトナーについて、順に説明する。
一般に、着色樹脂粒子の製造方法は、粉砕法等の乾式法、並びに乳化重合凝集法、懸濁重合法、及び溶解懸濁法等の湿式法に大別され、画像再現性等の印字特性に優れたトナーが得られ易いことから湿式法が好ましい。湿式法の中でも、ミクロンオーダーで比較的小さい粒径分布を持つトナーを得やすいことから、乳化重合凝集法、及び懸濁重合法等の重合法が好ましく、重合法の中でも懸濁重合法がより好ましい。
(A-1)重合性単量体組成物の調製工程
まず、重合性単量体、着色剤、さらに必要に応じて添加される帯電制御剤及び離型剤等のその他の添加物を混合し、重合性単量体組成物の調製を行う。重合性単量体組成物を調製する際の混合には、例えば、メディア式分散機を用いて行う。
本発明では、架橋性の重合性単量体を、モノビニル単量体100質量部に対して、通常、0.1~5質量部、好ましくは0.3~2質量部の割合で用いることが望ましい。
ブラック着色剤としては、カーボンブラック、チタンブラック、並びに酸化鉄亜鉛、及び酸化鉄ニッケル等の磁性粉等を用いることができる。
帯電制御剤としては、一般にトナー用の帯電制御剤として用いられているものであれば、特に限定されないが、帯電制御剤の中でも、重合性単量体との相溶性が高く、安定した帯電性(帯電安定性)をトナー粒子に付与させることができることから、正帯電性又は負帯電性の帯電制御樹脂が好ましく、さらに、正帯電性トナーを得る観点からは、正帯電性の帯電制御樹脂がより好ましく用いられる。
正帯電性の帯電制御剤としては、ニグロシン染料、4級アンモニウム塩、トリアミノトリフェニルメタン化合物及びイミダゾール化合物、並びに、好ましく用いられる帯電制御樹脂としてのポリアミン樹脂、並びに4級アンモニウム基含有共重合体、及び4級アンモニウム塩基含有共重合体等が挙げられる。
負帯電性の帯電制御剤としては、Cr、Co、Al、及びFe等の金属を含有するアゾ染料、サリチル酸金属化合物及びアルキルサリチル酸金属化合物、並びに、好ましく用いられる帯電制御樹脂としてのスルホン酸基含有共重合体、スルホン酸塩基含有共重合体、カルボン酸基含有共重合体及びカルボン酸塩基含有共重合体等が挙げられる。
本発明では、帯電制御剤を、モノビニル単量体100質量部に対して、通常、0.01~10質量部、好ましくは0.03~8質量部の割合で用いることが望ましい。帯電制御剤の添加量が、0.01質量部未満の場合にはカブリが発生することがある。一方、帯電制御剤の添加量が10質量部を超える場合には印字汚れが発生することがある。
分子量調整剤としては、一般にトナー用の分子量調整剤として用いられているものであれば、特に限定されず、例えば、t-ドデシルメルカプタン、n-ドデシルメルカプタン、n-オクチルメルカプタン、及び2,2,4,6,6-ペンタメチルヘプタン-4-チオール等のメルカプタン類;テトラメチルチウラムジスルフィド、テトラエチルチウラムジスルフィド、テトラブチルチウラムジスルフィド、N,N’-ジメチル-N,N’-ジフェニルチウラムジスルフィド、N,N’-ジオクタデシル-N,N’-ジイソプロピルチウラムジスルフィド等のチウラムジスルフィド類;等が挙げられる。これらの分子量調整剤は、それぞれ単独で、あるいは2種以上を組み合わせて用いてもよい。
本発明では、分子量調整剤を、モノビニル単量体100質量部に対して、通常0.01~10質量部、好ましくは0.1~5質量部の割合で用いることが望ましい。
上記離型剤は、モノビニル単量体100質量部に対して、好ましくは0.1~30質量部用いられ、更に好ましくは1~20質量部用いられる。
本発明では、重合性単量体と着色剤を含む重合性単量体組成物を、分散安定剤を含む水系媒体中に分散させ、重合開始剤を添加した後、重合性単量体組成物の液滴形成を行う。液滴形成の方法は特に限定されないが、例えば、(インライン型)乳化分散機(株式会社荏原製作所製、商品名「マイルダー」)、高速乳化分散機(特殊機化工業製、商品名「T.K.ホモミクサー MARK II型」)等の強攪拌が可能な装置を用いて行う。
上記(A-2)のようにして、液滴形成を行い、得られた水系分散媒体を加熱し、重合を開始し、着色樹脂粒子の水分散液を形成する。
重合性単量体組成物の重合温度は、好ましくは50℃以上であり、更に好ましくは60~95℃である。また、重合の反応時間は好ましくは1~20時間であり、更に好ましくは2~15時間である。
着色樹脂粒子が分散している水系媒体中に、シェル層を形成するための重合性単量体(シェル用重合性単量体)と重合開始剤を添加し、重合することでコアシェル型の着色樹脂粒子を得ることができる。
重合により得られた着色樹脂粒子の水分散液は、重合終了後に、常法に従い、ろ過、分散安定化剤の除去を行う洗浄、脱水、及び乾燥の操作が、必要に応じて数回繰り返されることが好ましい。
粉砕法を採用して着色樹脂粒子を製造する場合、以下のようなプロセスにより行われる。
まず、結着樹脂、着色剤、さらに必要に応じて添加される帯電制御剤及び離型剤等のその他の添加物を混合機、例えば、ボールミル、V型混合機、ヘンシェルミキサー(:商品名)、高速ディゾルバ、インターナルミキサー、フォールバーグ等を用いて混合する。次に、上記により得られた混合物を、加圧ニーダー、二軸押出混練機、ローラ等を用いて加熱しながら混練する。得られた混練物を、ハンマーミル、カッターミル、ローラミル等の粉砕機を用いて、粗粉砕する。更に、ジェットミル、高速回転式粉砕機等の粉砕機を用いて微粉砕した後、風力分級機、気流式分級機等の分級機により、所望の粒径に分級して粉砕法による着色樹脂粒子を得る。
上述の(A)懸濁重合法、又は(B)粉砕法等の製造方法により、着色樹脂粒子が得られる。
以下、トナーを構成する着色樹脂粒子について述べる。なお、以下で述べる着色樹脂粒子は、コアシェル型のものとそうでないもの両方を含む。
上記着色樹脂粒子の平均円形度が0.96未満の場合、印字の細線再現性が悪くなるおそれがある。
本発明に外添剤として使用されるコアシェル型複合微粒子(以下、単に「複合微粒子」と称することがある。)は、コア粒子に樹脂微粒子を用いることで容易に粒径を制御でき、更には後述する好適な方法であるゾルゲル法によって無機酸化物を被覆することにより、焼成なしに調製できることから真比重を低く制御できる。また、コア粒子が樹脂微粒子であることから比較的柔らかく、感光体を傷つけることも軽減される。
上記ii)の合成方法は、上記iii)の方法において樹脂微粒子を重合反応により合成すること以外は、上記iii)の方法と同様である。したがって、以下、iii)の方法について具体的に説明する。
乳化重合は、従来から公知の乳化重合法が採用できる。乳化重合に際しては、乳化剤、重合開始剤、分子量調整剤等の通常の重合に用いられる重合副資材を使用することができる。
好ましく用いられるモノビニル単量体と架橋性単量体の割合は、全単量体の内、架橋性単量体の割合が0.1~20質量%であることが好ましく、0.3~10質量%であることがより好ましく、0.5~5質量%であることが更に好ましい。
乳化剤の使用量は、乳化重合に使用する単量体全量100質量部に対して、通常、0.05~5質量部、好ましくは0.05~2質量部である。
分子量調整剤の具体例は、α-メチルスチレンダイマー;t-ドデシルメルカプタン、n-ドデシルメルカプタン、オクチルメルカプタン等のメルカプタン類;四塩化炭素、塩化メチレン、臭化メチレン等のハロゲン化炭化水素;テトラエチルチウラムダイサルファイド、ジペンタメチレンチウラムダイサルファイド、ジイソプロピルキサントゲンダイサルファイド等の含硫黄化合物である。これらの分子量調整剤を単独で、あるいは2種類以上組み合わせて使用できる。
チタンアルコキサイドを溶解させた水及び/又は水性媒体中に、母体となる樹脂微粒子を分散させた後、この分散溶液を、アルカリを加えてある水及び/又は水性媒体中に滴下するか、若しくは上記分散溶液中に、アルカリを加えてある水及び/又は水性媒体を滴下する。この方法によると、樹脂微粒子が含有されている分散溶液中に溶解していたチタンアルコキサイドが、アルカリの存在下で加水分解及び重縮合を起こし、徐々に不溶化していき、更に、疎水性相互作用から樹脂微粒子の表面に堆積することになる。この結果、樹脂微粒子の表面に、チタニアを含む粒状塊同士が固着されることによって形成される被膜層が形成される。この手法において、チタニアの粒状塊を樹脂微粒子表面に選択的に被膜させるために、チタンアルコキサイドを溶解させた水及び/又は水性媒体中に、母体となる樹脂微粒子を分散させた後、攪拌、必要ならば熱をかけることによって、チタンアルコキサイドが溶解した媒体中に樹脂微粒子を分散させることが好ましい。
上記シランカップリング剤としては、例えば、ヘキサメチルジシラザン等のジシラザン;環状シラザン;トリメチルシラン;トリメチルクロルシラン;ジメチルジクロルシラン、メチルトリクロルシランアリルジメチルクロルシラン、ベンジルジメチルクロルシラン、メチルトリメトキシシラン、メチルトリエトキシシラン、イソブチルトリメトキシシラン、ジメチルジメトキシシラン、ジメチルジエトキシシラン、トリメチルメトキシシラン、ヒドロキシプロピルトリメトキシシラン、フェニルトリメトキシシラン、n-オクタデシルトリメトキシシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、γ-メタクリルオキシプロピルトリメトキシシラン、及びビニルトリアセトキシシラン等のアルキルシラン化合物、並びにγ-アミノプロピルトリエトキシシラン、γ-(2-アミノエチル)アミノプロピルトリメトキシシラン、γ-(2-アミノエチル)アミノプロピルメチルジメトキシシラン、N-フェニル-3-アミノプロピルトリメトキシシラン、N-(2-アミノエチル)3-アミノプロピルトリメトキシシラン、及びN-β-(N-ビニルベンジルアミノエチル)-γ-アミノプロピルトリメトキシシラン等のアミノシラン化合物;等が挙げられる。これらは、それぞれ単独で、あるいは2種以上組み合わせて用いることができる。
上記シリコーンオイルとしては、例えば、ジメチルポリシロキサン、メチルハイドロジェンポリシロキサン、メチルフェニルポリシロキサン、及びアミノ変性シリコーンオイル等が挙げられる。これらは、それぞれ単独で、あるいは2種以上組み合わせて用いることができる。
疎水化処理剤は、上記のうち、1種あるいは2種以上含有してもよく、シランカップリング剤、またはシリコーンオイルを用いると、得られるトナーは、高画質が得られるものとなるのでより好ましい。
具体的には、外添剤として用いるコアシェル型複合微粒子を高速で攪拌しながら、上記疎水化処理剤を滴下または噴霧する方法に代表される乾式法、及び上記疎水化処理剤を有機溶媒に溶解し、疎水化処理剤を含有する有機溶媒を攪拌しながらコアシェル型複合微粒子を添加する方法に代表される湿式法等が挙げられる。コアシェル型複合微粒子を均一に疎水化処理できることから湿式法が好ましい。
しかし、湿式法においては、ゾルゲル反応により得られたコアシェル型複合微粒子を、洗浄、濾別、乾燥した後に、そのコアシェル型複合微粒子を有機溶媒中に分散させて、疎水化処理剤を接触させる方法が好ましい。この好ましい方法により得られた、有機溶媒中に分散した疎水化されたコアシェル型複合微粒子は、減圧蒸留により有機溶媒を除去した後、乾燥し、必要に応じて解砕して用いる。
上述の製造方法により、コアシェル型複合微粒子が得られる。以下、本発明の外添剤として用いられるコアシェル型複合微粒子について述べる。
以下、無機成分がシリカの場合における、シリカ成分の体積比率の数値範囲について述べる。コアシェル型複合微粒子の全体積を100体積%としたときの、当該複合微粒子のシリカ成分の体積比率は45~75体積%である。当該体積比率が45体積%未満である場合には、後述するトナーの流動性が低下するおそれがある。一方、当該体積比率が75体積%を超える場合には、後述するトナーの環境安定性が悪化し、且つ、トナーの高温高湿環境下におけるカブリが悪化するおそれがある。
コアシェル型複合微粒子の全体積を100体積%としたときの、当該複合微粒子のシリカ成分の体積比率は50~70体積%であることがより好ましく、55~65体積%であることが更に好ましい。
当該体積比率が25体積%未満である場合には、金属酸化物量が少なくなるため、低温低湿(L/L)環境下における帯電上昇の抑制効果が発現しないおそれがある。一方、当該体積比率が75体積%を超える場合には、金属酸化物量が多いため、高温高湿(H/H)環境下で帯電が低下しやすくなり、かぶりが悪化してしまうおそれがある。
コアシェル型複合微粒子の全体積を100体積%としたときの、当該複合微粒子の無機成分の体積比率は30~70体積%であることがより好ましく、45~70体積%であることが更に好ましく、50~70体積%であることが特に好ましい。
無機成分がシリカ、アルミナ、チタニア、及びジルコニアからなる群より選ばれる2以上の無機成分を含む場合には、コアシェル型複合微粒子の全体積を100体積%としたときの、当該複合微粒子の無機成分の総体積比率は、45~75体積%であることが好ましく、50~70体積%であることがより好ましく、55~70体積%であることが更に好ましい。
まず、原子吸光分析法等を利用して、当該微粒子がケイ素、アルミニウム、チタン及び/又はジルコニウムを含有しているか否かを確認する。
当該微粒子がケイ素、アルミニウム、チタン及び/又はジルコニウムを含有していることが判明した場合、当該微粒子の個数平均粒径を上記の方法と同様に測定する。続いて、当該微粒子を、フッ化水素酸に投入して、シリカ、アルミナ、チタニア及び/又はジルコニアを溶解させ、水で洗浄した後に乾燥して、上記と同様にコアである樹脂微粒子の個数平均粒径を測定する。このように測定した無機成分溶解前後の2つの個数平均粒径の値から、当該微粒子の無機成分の体積比率を計算することができる。
コアシェル型複合微粒子の吸着水分量は、0.5~2.0質量%であることがより好ましく、0.8~1.5質量%であることが更に好ましい。
本発明では、吸着水分量は、水分吸・脱着測定装置(IGAsorp、日本シイベルヘグナー社製)を用いて、サンプルを乾燥窒素気流下に1時間放置し、その後、32℃、湿度80%の空気中で1時間水分を吸着させて、水分を吸着した試料の質量を測定した。測定結果から、(増加した質量/サンプル質量)×100を吸着水分量(質量%)とした。
コアシェル型複合微粒子のブローオフ帯電量の値は、+1000~+4000μC/gであることが好ましい。当該値が+1000μC/g未満である場合には、トナーの帯電量が低下し、かつカブリが発生しやすくなるおそれがある。一方、当該値が+4000μC/gを超える値である場合には、コアシェル型複合微粒子の調製が困難である。
コアシェル型複合微粒子のブローオフ帯電量の値は、+1500~+3000μC/gであることがより好ましく、+1700~+2500μC/gであることが更に好ましい。
コアシェル型複合微粒子の個数平均粒径は、40~250nmであることがより好ましく、50~200nmであることがさらに好ましい。
本発明のトナーは、上記着色樹脂粒子を、上記コアシェル型複合微粒子と共に混合攪拌し、当該コアシェル型複合微粒子を着色樹脂粒子の表面に好適に付着添加(外添)させることにより得られる。
コアシェル型複合微粒子の添加量は、着色樹脂粒子100質量部に対して0.15~1.0質量部が好ましく、0.2~0.8質量部がより好ましい。
当該他の外添剤としては、シリカ、酸化チタン、酸化アルミニウム、酸化亜鉛、酸化錫、炭酸カルシウム、燐酸カルシウム、及び/又は酸化セリウム等からなる無機微粒子;ポリメタクリル酸メチル樹脂、シリコーン樹脂、及び/又はメラミン樹脂等からなる有機微粒子;等が挙げられる。これらの中でも、無機微粒子が好ましく、無機微粒子の中でも、シリカ、及び/又は酸化チタンが好ましく、特にシリカからなる微粒子が好適である。
なお、コアシェル型複合微粒子と併用する当該他の外添剤は、1種類のみでもよいし、2種類以上でもよい。
他の外添剤の添加量は、0.1~6質量部が好ましく、0.3~5重量部がより好ましく、0.5~4重量部が更に好ましい。
なお、当該他の外添剤の個数平均粒径は、15~80nmであるのがより好ましい。
上記工程を経て得られる本発明の第1のトナーは、外添剤として樹脂微粒子の表面がシリカで被覆されているコアシェル型複合微粒子を使用することにより、経時的に安定した帯電性をトナー粒子に付与し、多枚数の連続印刷を行っても、カブリ等による画質の劣化が起こり難く、さらに優れた流動性を有する静電荷像現像用トナーである。
また、上記工程を経て得られる本発明の第2のトナーは、外添剤として樹脂微粒子の表面が、アルミナ、チタニア及び/又はジルコニアで被覆されているコアシェル型複合微粒子を使用することにより、低温低湿環境下におけるトナー帯電量の上昇が抑制され、同環境下においても細線再現性が損なわれることなく安定した印字が行え、且つ、帯電量の上昇により発生する印字不具合などがなく、良好な画質が得られる静電荷像現像用トナーである。
本発明のトナーは、流動性の値が82~100であることがより好ましく、85~100であることが更に好ましい。
次に、篩の上に測定するトナー試料を所定量載せる。2種類以上の篩を使用する場合には、一番上に重ねた篩、すなわち、目開きの最も大きい篩の上にトナー試料を載せる。
続いて、粉体測定機を用いて、篩を一定の振動条件下において一定時間振動させた後、篩上に残ったトナーの質量を測定する。2種類以上の篩を使用する場合には、篩ごとに残ったトナーの質量を測定する。
最後に、トナーの全質量に対する、篩上に残ったトナーの質量の割合を算出する。当該割合を基に算出した、トナーの全質量に対する篩を通ったトナーの割合を百分率で表した値を流動性の値とする。2種類以上の篩を使用する場合には、全ての篩について篩上に残ったトナーの質量の割合を算出した後、当該割合を合算し、流動性の値を算出する。この場合、篩ごとに1以下の係数を割り当てて、篩上に残ったトナーの質量の割合と当該係数との積を合算してもよい。例えば、2種類の篩を使用する場合に、目開きの最も大きい篩Aに係数1を割り当て、目開きの最も小さい篩Bに係数0.6を割り当てると仮定する。この場合、篩Aの上に残ったトナーの質量の割合αと係数1との積、及び、篩Bの上に残ったトナーの質量の割合βと係数0.6との積を合算した値である(α+0.6β)を基に、流動性を算出する。このように、適宜係数を割り当てることにより、より精確にトナーの流動性を評価することができる。
本実施例及び比較例において行った試験方法は以下のとおりである。
I-1.コアシェル型複合微粒子の製造
[製造例I-1]
窒素置換した攪拌機付きの容器に、ソフト型ドデシルベンゼンスルホン酸3部をイオン交換水150部に溶解させ、次いでスチレン95部を乳化させて重合性単量体エマルションを作製した。エマルションの温度を80℃に昇温した後、10部のイオン交換水に溶解した過硫酸カリウム0.6部を加え2時間重合させた。続いて反応機の温度を40℃まで低下させたのちジビニルベンゼンを5部加えて2時間攪拌を行った後、温度を85℃に昇温して水2部に溶解した過硫酸カリウム0.1部を加えて4時間重合反応を実施し、反応停止剤としてハイドロキノン水溶液を添加して重合を終了した。この時の重合転化率は99%であった。限外ろ過によって水溶性物質を除去した。エマルションのpH及び濃度を調整して、固形分濃度が50%、pHが8.5の樹脂微粒子エマルションを得た。このエマルションの一部を乾燥させて、後述する樹脂微粒子の個数平均粒径の測定に供した。
上記製造例I-1において、ソフト型ドデシルベンゼンスルホン酸の添加量を3部から8部に変更して重合した結果、個数平均粒径が50nmの樹脂微粒子エマルションを得たこと、及びコアシェル型複合微粒子を製造するときに、テトラエトキシシランの添加量を600部から700部に変更し、かつ1-メチルトリエトキシシランの添加量を150部から200部に変更したこと以外は、上記製造例I-1と同様にしてコアシェル型複合微粒子I-Bを製造した。
上記製造例I-1において、ゾルゲル反応の時間を48時間から72時間に変更した以外は、上記製造例I-1と同様にしてコアシェル型複合微粒子I-Cを製造した。
上記製造例I-1において、ソフト型ドデシルベンゼンスルホン酸の添加量を3部から0.8部に変更して重合した結果、個数平均粒径が150nmの樹脂微粒子エマルションを得たこと、及びコアシェル型複合微粒子を製造するときに、テトラエトキシシランの添加量を600部から500部に変更し、1-メチルトリエトキシシランの添加量を150部から120部に変更したこと以外は、上記製造例I-1と同様にしてコアシェル型複合微粒子I-Dを製造した。
上記製造例I-1において、最初の重合で用いる重合性単量体を、スチレン95部及びジビニルベンゼン5部から、スチレン100部に変更し、後に添加するジビニルベンゼン5部を用いなかったこと以外は、上記製造例I-1と同様にしてコアシェル型複合微粒子I-Eを製造した。
アクリル/スチレン系樹脂微粒子(綜研化学(株)製、商品名:MP-5500、個数平均粒径400nm)1.0質量部をメタノール100質量部に分散させた後、ケイ素化合物として、20質量部のテトラエトキシシラン、5.0質量部のメチルトリエトキシシランを溶解した。この状態で50℃に加熱し、1時間攪拌させ樹脂微粒子をシランアルコキサイドが溶解している媒体中に分散させた。次いで、この溶液に、28質量%のNH4OH水溶液20質量部を滴下しながら加え、室温にて48時間攪拌することによって、ゾルゲル反応を行って、樹脂微粒子の表面にシリカの被覆を行った。
反応終了後に、得られた粒子を精製水で洗浄し、次いでメタノールで洗浄した後、粒子を濾別、乾燥することにより、樹脂微粒子をシリカコートしたコアシェル型複合微粒子I-Fを製造した。
製造例I-6のアクリル/スチレン系樹脂微粒子(綜研化学(株)製、商品名:MP-5500、個数平均粒径400nm)1.0質量部を、アクリル/スチレン系樹脂微粒子(綜研化学(株)製、商品名:MP-1450、個数平均粒径250nm)1.0質量部に変えたこと以外は、上記製造例I-6と同様にして、コアシェル型複合微粒子I-Gを製造した。
上記製造例I-1~I-7から得られたコアシェル型複合微粒子I-A~I-G、疎水化処理されたシリカ微粒子(クラリアント社製、商品名:H05TA。以下、シリカ微粒子I-Aと称する場合がある。)、及び、疎水化処理されたシリカ微粒子(キャボット社製、商品名:TG-C321。以下、シリカ微粒子I-Bと称する場合がある。)について、個数平均粒径、吸着水分量及び帯電量の測定を行った。なお、コアシェル型複合微粒子I-A~I-Gについては、これらの複合微粒子の原料である樹脂微粒子の個数平均粒径も測定し、コアシェル型複合微粒子のシリカ成分の比率を算出した。
コアシェル型複合微粒子等、及び原料である樹脂微粒子の個数平均粒径は、以下のような方法で測定した。すなわち、これらの各微粒子について、電界放出型走査電子顕微鏡(日立製作所社製、製品名:S-4700)を用いて、10,000倍の倍率で写真を撮影し、その写真を画像処理解析装置(ニレコ製、商品名:ルーゼックスIID)により、フレーム面積に対する粒子の面積率:最大2%、トータル処理粒子数:100個の条件で微粒子の投影面積に対応する円相当径を粒子毎に算出し、その平均値を求めた。
コアシェル型複合微粒子I-A~I-Gについて、被覆されたシリカの体積がコアシェル型複合微粒子全体の体積に占める割合を、下記式に基づき算出した。
[シリカ成分の比率]=[{(4/3)π(r2/2)3-(4/3)π(r1/2)3}/{(4/3)π(r2/2)3}]×100={(r2 3-r1 3)/(r2 3)}×100
(上記式中、r1はコアとなる樹脂微粒子の個数平均粒径、r2はコアシェル型複合微粒子の個数平均粒径である。)
吸着水分量の測定には、水分吸脱着測定装置(ハイデン社製、商品名:IGAsorp)を用いた。当該装置内に、試料であるコアシェル型複合微粒子等を、乾燥窒素気流下に1時間放置した後、試料の乾燥質量を測定し、その後、32℃、湿度80%の空気中で1時間水分を吸着させて、水分を吸着した試料の質量を測定した。
吸着水分量(質量%)は、{(水分を吸着した試料の質量-乾燥した試料の質量)/乾燥した試料の質量)}×100から算出した。
キャリア(パウダーテック社製、商品名「F96-80」) 9.95gと、試料0.05gを秤量し、容積100ccのガラス瓶に入れ、30分間、150回転/分の回転数で回転させた後、ブローオフメーター(東芝ケミカル社製、商品名「TB-203」)を用い、窒素ガス4.5kPaの圧力でブロー、9.5kPaの圧力で吸引して、ブローオフ帯電量を測定した。
測定は、温度23℃、相対湿度50%の環境下で行った。このブローオフ帯電量の測定により、外添剤の帯電極性が分かる。
摩擦帯電量(μC/g)=測定試料混合物の帯電量(μC)/(測定試料化合物の質量(g)×測定試料の濃度(質量%))
I-3-1.コア用重合性単量体組成物の調製
モノビニル単量体としてスチレン83部及びn-ブチルアクリレート17部、ブラック着色剤としてカーボンブラック(三菱化学社製、商品名:#25B)7部、帯電制御剤として正帯電性の帯電制御樹脂(藤倉化成社製、商品名:FCA-207P、4級アンモニウム塩基含有スチレン/アクリル樹脂)1部、架橋性の重合性単量体としてジビニルベンゼン0.6部、分子量調整剤としてt-ドデシルメルカプタン1.9部、及びマクロモノマーとしてポリメタクリル酸エステルマクロモノマー(東亜合成社製、商品名:AA6、得られる重合体のTg=94℃)0.25部を、攪拌装置で攪拌、混合した後、さらにメディア式分散機を用いて均一に分散させた。ここに、離型剤としてジペンタエリスリトールヘキサミリステート5部を添加、混合、溶解して、重合性単量体組成物を得た。
他方、室温下で、イオン交換水250部に塩化マグネシウム(水溶性多価金属塩)10.2部を溶解した水溶液に、イオン交換水50部に水酸化ナトリウム(水酸化アルカリ金属)6.2部を溶解した水溶液を、攪拌下で徐々に添加して、水酸化マグネシウムコロイド(難水溶性の金属水酸化物コロイド)分散液を調製した。
上記水酸化マグネシウムコロイド分散液に、室温下で、上記重合性単量体組成物を投入し、攪拌した。そこへ重合開始剤としてt-ブチルパーオキシ-2-エチルヘキサノエート(日本油脂社製、商品名:パーブチルO)6部を添加した後、インライン型乳化分散機(荏原製作所社製、商品名:エバラマイルダー)を用いて、15,000rpmの回転数で10分間高速剪断攪拌して分散を行い、重合性単量体組成物の液滴形成を行った。
上記重合性単量体組成物の液滴が分散した懸濁液(重合性単量体組成物分散液)を、攪拌翼を装着した反応器内に投入し、90℃に昇温し、重合反応を開始させた。重合転化率が、ほぼ100%に達したときに、シェル用重合性単量体としてメチルメタクリレート1部、及びイオン交換水10部に溶解したシェル用重合開始剤である2,2’-アゾビス(2-メチル-N-(2-ヒドロキシエチル)-プロピオンアミド)(和光純薬社製、商品名:VA-086、水溶性)0.3部を添加し、90℃で4時間反応を継続した後、水冷して反応を停止し、コアシェル型構造を有する着色樹脂粒子の水分散液を得た。
上記着色樹脂粒子の水分散液を、室温下で、硫酸を攪拌しながら滴下し、pHが6.5以下となるまで酸洗浄を行った。次いで、濾過分離を行い、得られた固形分にイオン交換水500部を加えて再スラリー化させて、水洗浄処理(洗浄・濾過・脱水)を数回繰り返し行った。次いで、濾過分離を行い、得られた固形分を乾燥機の容器内に入れ、45℃で48時間乾燥を行い、乾燥した着色樹脂粒子を得た。
測定試料(着色樹脂粒子)を約0.1g秤量し、ビーカーに取り、分散剤としてアルキルベンゼンスルホン酸水溶液(富士フイルム社製、商品名:ドライウエル)0.1mLを加えた。そのビーカーへ、更にアイソトンIIを10~30mL加え、20Wの超音波分散機で3分間分散させた後、粒径測定機(ベックマン・コールター社製、商品名:マルチサイザー)を用いて、アパーチャー径;100μm、測定粒子個数;100,000個の条件下で、着色樹脂粒子の体積平均粒径(Dv)、及び個数平均粒径(Dn)を測定し、粒径分布(Dv/Dn)を算出した。その結果、得られた着色樹脂粒子の体積平均粒径(Dv)は9.7μm、粒径分布(Dv/Dn)は1.14であった。
まず、容器中に、予めイオン交換水10mLを入れ、その中に分散剤としてアルキルベンゼンスルホン酸水溶液(富士フイルム社製、商品名:ドライウエル)0.2mLを加え、更に着色樹脂粒子0.2gを加え、超音波分散機で60W(Watt)、3分間分散処理を行った。測定時の着色樹脂粒子濃度が3,000~10,000個/μLとなるように調整し、0.4μm以上の円相当径の着色樹脂粒子1,000~10,000個についてフロー式粒子像分析装置(シメックス社製、商品名:FPIA-2100)を用いて測定した。測定値から平均円形度を求めたところ、得られた着色樹脂粒子の平均円形度は0.987であった。
上記「I-1.コアシェル型複合微粒子の製造」の項で説明したコアシェル型複合微粒子等、及び、上記「I-3.着色樹脂粒子の製造及び物性評価」の項で説明した着色樹脂粒子を使用して、静電荷像現像用トナーを製造した。
上記着色樹脂粒子100部に、上記製造例I-1で製造したコアシェル型複合微粒子I-Aを1.2部、疎水化処理された個数平均一次粒径が22nmのシリカ微粒子(キャボットコーポレーション社製、商品名:TG-7120)を0.8部添加し、FMミキサー(日本コークス株式会社製 商品名:FM-10)を用いて、周速40m/sで5分間混合攪拌して、外添処理を行い、実施例I-1の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-2で製造したコアシェル型複合微粒子I-Bに変更したこと以外は、実施例I-1と同様にして実施例I-2の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-3で製造したコアシェル型複合微粒子I-Cに変更したこと以外は、実施例I-1と同様にして実施例I-3の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-4で製造したコアシェル型複合微粒子I-Dに変更したこと以外は、実施例I-1と同様にして実施例I-4の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-5で製造したコアシェル型複合微粒子I-Eに変更したこと以外は、実施例I-1と同様にして実施例I-5の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、シリカ微粒子I-Aに変更したこと以外は、実施例I-1と同様にして比較例I-1の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、シリカ微粒子I-Bに変更したこと以外は、実施例I-1と同様にして比較例I-2の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-6で製造したコアシェル型複合微粒子I-Fに変更したこと以外は、実施例I-1と同様にして比較例I-3の静電荷像現像用トナーを得た。
上記製造例I-1で製造したコアシェル型複合微粒子I-Aを、上記製造例I-7で製造したコアシェル型複合微粒子I-Gに変更したこと以外は、実施例I-1と同様にして比較例I-4の静電荷像現像用トナーを得た。
実施例I-1~I-5、及び比較例I-1~I-4の静電荷像現像用トナーについて、流動性評価、常温常湿(N/N)環境下又は高温高湿(H/H)環境下におけるトナー帯電量の測定、常温常湿(N/N)環境下又は高温高湿(H/H)環境下におけるカブリ評価、及び印字耐久性試験を行った。
目開きが各々150μm、75μm、及び45μmの3種の篩をこの順に上から重ねて、一番上の目開き150μmの篩の上に、測定する静電荷像現像用トナー4gを精秤して載せた。次いで、この重ねた3種の篩を、粉体測定機(細川ミクロン社製、商品名:パウダーテスター)を用いて、振動強度目盛り4の条件で15秒間振動した後、各篩上に残った静電荷像現像用トナーの質量を測定した。各測定値を以下の式(I-1)~(I-3)に代入して、a、b、及びcの値を求めた。これらa、b、及びcの値を式(I-4)に代入して、流動性の値を算出した。1サンプルにつき3回測定し、その平均値を求めた。
a=〔(150μm篩に残った重合体質量(g))/4g〕×100 式(I-1)
b=〔(75μm篩に残った重合体質量(g))/4g〕×100×0.6 式(I-2)
c=〔(45μm篩に残った重合体質量(g))/4g〕×100×0.2 式(I-3)
流動性=100-(a+b+c) 式(I-4)
市販の非磁性一成分現像方式のプリンター(HL-3040CN)を用いた。現像装置のトナーカートリッジに、トナーを充填した後、白べた印字を1枚行い、エレクトロメーター(アドバンテスト製、商品名:TR8652)にて常温常湿(N/N)環境下(温度:23℃、湿度:50%)で現像ロール上のトナーを採取し、帯電量を測定した。測定された帯電量値を採取したトナーの重量で割ることでトナー帯電量を算出した。
(測定された帯電量(μC)/採取したトナー重量(g))=トナー帯電量(μC/g)
現像装置のトナーカートリッジに、トナーを充填した後、高温高湿(H/H)環境下(温度:35℃、湿度:80%)に24時間放置した後、その環境下で帯電量を測定した以外は、常温常湿帯電量と同様にしてトナー帯電量を算出した。
市販の非磁性一成分現像方式のプリンター(HL-3040CN)を用いた。現像装置のトナーカートリッジに、トナーを充填した後、常温常湿(N/N)環境下(温度:23℃、湿度:50%)に24時間放置した。放置後、白べた印字を一枚行い、カブリがないかを目視で確認した。その後、白色度計(日本電色社製)を用いて白べた印字物の紙面上の白色度を測定した。
{(印字前の白度)-(白べた印字物の白度)}=カブリ濃度
とし、カブリ濃度を算出した。
現像装置のトナーカートリッジに、トナーを充填した後、高温高湿(H/H)環境下(温度:35℃、湿度:80%)に24時間放置した後、その環境下でカブリを測定した以外は常温常湿カブリ評価と同様にしてカブリ濃度を算出した。
印字耐久性試験には、市販の非磁性一成分現像方式のプリンター(HL-3040CN)を用い、現像装置のトナーカートリッジに、トナーを充填した後、印字用紙をセットした。常温常湿(N/N)環境下(温度:23℃、湿度:50%)で、24時間放置した後、同環境下にて、5%印字濃度で10,000枚まで連続印刷を行った。
500枚毎に、黒ベタ印字(印字濃度100%)を行い、反射式画像濃度計(マクベス社製、商品名:RD918)を用いて黒ベタ画像の印字濃度を測定した。さらに、その後、白ベタ印字(印字濃度0%)を行い、白ベタ印字の途中でプリンターを停止させ、現像後の感光体上における非画像部のトナーを、粘着テープ(住友スリーエム社製、商品名:スコッチメンディングテープ810-3-18)に付着させた後、剥ぎ取り、それを印字用紙に貼り付けた。次に、その粘着テープを貼り付けた印字用紙の白色度(B)を、白色度計(日本電色社製、商品名:ND-1)で測定し、同様にして、未使用の粘着テープだけを印字用紙に貼り付け、その白色度(A)を測定し、この白色度の差(B-A)をカブリ値(%)とした。この値が小さいほど、カブリが少なく良好であることを示す。
印字濃度が1.30以上で、且つカブリ値が3%以下の画質を維持できる連続印刷枚数を調べた。
なお、表I-2中、「10000<」とあるのは、10,000枚の時点においても、印字濃度が1.30以上で、且つカブリ値が3%以下の画質を維持できたことを示す。
まず、比較例I-1のトナーについて検討する。比較例I-1のトナーは、常温常湿(N/N)環境下におけるトナー帯電量が37μC/g、高温高湿(H/H)環境下におけるトナー帯電量が25μC/gであり、いずれも中程度の帯電量を示した。また、比較例I-1のトナーは、常温常湿(N/N)環境下におけるカブリ濃度が0.2、常温常湿(N/N)環境下におけるカブリ発生枚数が10,000枚を超える結果となり、少なくとも常温常湿(N/N)環境下における印字耐久性に問題は見られなかった。
しかし、比較例I-1のトナーの流動性の値は80であり、流動性にやや劣る結果を示した。また、比較例I-1のトナーの高温高湿(H/H)環境下におけるカブリ濃度は8であり、後述する実施例I-1~I-5の結果と比較して、3倍以上のカブリが発生することが分かる。
これらの結果から、従来のシリカ微粒子であるシリカ微粒子I-Aを使用した比較例I-1のトナーは、流動性及び高温高湿(H/H)環境下における印字耐久性に劣ることが分かる。
しかし、比較例I-2のトナーは、常温常湿(N/N)環境下におけるトナー帯電量が18μC/g、高温高湿(H/H)環境下におけるトナー帯電量が14μC/gであり、実施例I-1~I-5及び比較例I-1~I-4のトナー中、最も低い帯電量を示した。また、比較例I-2のトナーの高温高湿(H/H)環境下におけるカブリ濃度は12であり、後述する実施例I-1~I-5の結果と比較して、5倍以上のカブリが発生することが分かる。
これらの結果から、従来のシリカ微粒子であるシリカ微粒子I-Bを使用した比較例I-2のトナーは、常温常湿(N/N)環境下及び高温高湿(H/H)環境下における帯電量が低く、かつ高温高湿(H/H)環境下における印字耐久性に劣ることが分かる。
しかし、比較例I-3のトナーの流動性の値は69であり、実施例I-1~I-5及び比較例I-1~I-4のトナー中、最も劣った流動性を示した。また、比較例I-3のトナーの常温常湿(N/N)環境下におけるカブリ濃度は2.8であり、後述する実施例I-1~I-5の結果と比較して、常温常湿(N/N)環境下においては4倍以上のカブリが発生することが分かる。さらに、比較例I-3のトナーの高温高湿(H/H)環境下におけるカブリ濃度は25であり、後述する実施例I-1~I-5の結果と比較して、高温高湿(H/H)環境下においては10倍以上のカブリが発生することが分かる。
これらの結果から、シリカ成分の体積比率が、本発明に使用される複合微粒子よりも低いコアシェル型複合微粒子を使用した比較例I-3のトナーは、流動性、並びに常温常湿(N/N)環境下及び高温高湿(H/H)環境下における印字耐久性に劣ることが分かる。
これらの結果から、シリカ成分の体積比率が、本発明に使用される複合微粒子よりも極めて低いコアシェル型複合微粒子を使用した比較例I-4のトナーは、常温常湿(N/N)環境下及び高温高湿(H/H)環境下における帯電量が低く、流動性、並びに常温常湿(N/N)環境下及び高温高湿(H/H)環境下における印字耐久性に劣ることが分かる。
II-1.コアシェル型複合微粒子の製造
[製造例II-1]
窒素置換した攪拌機付きの容器に、ソフト型ドデシルベンゼンスルホン酸3部をイオン交換水150部に溶解させ、次いでスチレン95部を乳化させて重合性単量体エマルションを作製した。エマルションの温度を80℃に昇温した後、10部のイオン交換水に溶解した過硫酸カリウム0.6部を加え2時間重合させた。続いて反応機の温度を40℃まで低下させたのちジビニルベンゼンを5部加えて2時間攪拌を行った後、温度を85℃に昇温して水2部に溶解した過硫酸カリウム0.1部を加えて4時間重合反応を実施し、反応停止剤としてハイドロキノン水溶液を添加して重合を終了した。この時の重合転化率は99%であった。限外ろ過によって水溶性物質を除去した。エマルションのpH及び濃度を調整して、固形分濃度が50%、pHが8.5の樹脂微粒子エマルションを得た。このエマルションの一部を乾燥させて、後述する樹脂微粒子の個数平均粒径の測定に供した。樹脂微粒子の個数平均粒径は80nmであった。
上記製造例II-1において、ソフト型ドデシルベンゼンスルホン酸の添加量を3部から8部に変更して重合した結果、個数平均粒径が50nmの樹脂微粒子エマルションを得たこと、及びコアシェル型複合微粒子を製造するときに、テトラエトシキチタンの添加量を750部から900部に変更したこと以外は、上記製造例II-1と同様にしてコアシェル型複合微粒子II-Bを製造した。
上記製造例II-1において、ゾルゲル反応の時間を48時間から72時間に変更した以外は上記製造例II-1と同様にしてコアシェル型複合微粒子II-Cを製造した。
上記製造例II-1において、最初の重合で用いる重合性単量体を、スチレン95部及びジビニルベンゼン5部から、スチレン100部に変更し、後に添加するジビニルベンゼン5部を用いなかったこと以外は、上記製造例II-1と同様にしてコアシェル型複合微粒子II-Dを製造した。
上記製造例II-1において、コアシェル型複合微粒子を製造するときに、テトラエトキシチタン750部をトリエトキシアルミニウム750部に変更した以外は、上記製造例II-1と同様にしてコアシェル型複合微粒子II-Eを製造した。
上記製造例II-1において、ソフト型ドデシルベンゼンスルホン酸の添加量を3部から0.8部に変更して重合した結果、個数平均粒径が150nmの樹脂微粒子エマルションを得たこと、及びコアシェル型複合微粒子を製造するときに、テトラエトキシチタン750部をトリエトキシアルミニウム620部に変更したこと以外は、上記製造例II-1と同様にしてコアシェル型複合微粒子II-Fを製造した。
上記製造例II-1~II-6から得られたコアシェル型複合微粒子II-A~II-Fについて、個数平均粒径及び吸着水分量の測定を行った。なお、当該コアシェル型複合微粒子II-A~II-Fの原料である樹脂微粒子の個数平均粒径も測定し、コアシェル型複合微粒子の無機成分の比率を算出した。
コアシェル型複合微粒子、及び原料である樹脂微粒子の個数平均粒径は、以下のような方法で測定した。すなわち、これらの各微粒子について、電界放出形走査型電子顕微鏡(日立製作所製、S-4500形)を用いて観察を行った。累積300個以上になるように粒子径を測定し、個数平均粒径を算出した。
コアシェル型複合微粒子II-A~II-Fについて、被覆された無機成分の体積がコアシェル型複合微粒子全体の体積に占める割合を、下記式に基づき算出した。
[無機成分の比率]=[{(4/3)π(r2/2)3-(4/3)π(r1/2)3}/{(4/3)π(r2/2)3}]×100={(r2 3-r1 3)/(r2 3)}×100
(上記式中、r1はコアとなる樹脂微粒子の個数平均粒径、r2はコアシェル型複合微粒子の個数平均粒径である。)
吸着水分量の測定には、水分吸・脱着測定装置(IGAsorp、日本シイベルヘグナー社製)を用いた。装置内にサンプルを乾燥窒素気流化に1時間放置し、その後、32℃、湿度80%の空気中で1時間水分を吸着させて、水分を吸着した試料の質量を測定した。測定結果から、(増加した質量/サンプル質量)×100を吸着水分量(質量%)とした。
実施例シリーズIのI-3に記載した方法と同様の方法により、着色樹脂粒子の製造を行った。
得られた着色樹脂粒子について、実施例シリーズIのI-3に記載した方法と同様の方法により、体積平均粒径(Dv)の測定、粒径分布(Dv/Dn)の算出、及び平均円形度の算出を行った。その結果、得られた着色樹脂粒子の体積平均粒径(Dv)は9.7μm、粒径分布(Dv/Dn)は1.14、平均円形度は0.987であった。
上記「II-1.コアシェル型複合微粒子の製造」の項で説明したコアシェル型複合微粒子、及び、上記「II-3.着色樹脂粒子の製造及び物性評価」の項で説明した着色樹脂粒子を使用して、静電荷像現像用トナーを製造した。
上記着色樹脂粒子100部に、上記製造例II-1で製造したコアシェル型複合微粒子II-Aを0.5部、TG-7120(キャボットコーポレーション社製)を0.8部、NA50Y(日本アエロジル製)を1.0部添加し、FMミキサー(日本コークス株式会社製 商品名:FM-10)を用いて混合攪拌を行い、外添処理を行い、実施例II-1の静電荷像現像用トナーを得た。このときの攪拌羽根の周速は40m/sであり、攪拌時間は5分間とした。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを、上記製造例II-2で製造したコアシェル型複合微粒子II-Bに変更したこと以外は、実施例II-1と同様にして実施例II-2の静電荷像現像用トナーを得た。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを、上記製造例II-3で製造したコアシェル型複合微粒子II-Cに変更したこと以外は、実施例II-1と同様にして実施例II-3の静電荷像現像用トナーを得た。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを、上記製造例II-4で製造したコアシェル型複合微粒子II-Dに変更したこと以外は、実施例II-1と同様にして実施例II-4の静電荷像現像用トナーを得た。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを、上記製造例II-5で製造したコアシェル型複合微粒子II-Eに変更したこと以外は、実施例II-1と同様にして実施例II-5の静電荷像現像用トナーを得た。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを、上記製造例II-6で製造したコアシェル型複合微粒子II-Fに変更したこと以外は、実施例II-1と同様にして実施例II-6の静電荷像現像用トナーを得た。
上記製造例II-1で製造したコアシェル型複合微粒子II-Aを使用しなかったこと以外は、実施例II-1と同様にして比較例II-1の静電荷像現像用トナーを得た。
実施例II-1~II-6、及び比較例II-1の静電荷像現像用トナーについて、常温常湿(N/N)環境下又は高温高湿(H/H)環境下におけるカブリ試験、低温低湿(L/L)環境下における細線再現性の評価、及び常温常湿(N/N)環境下における印字耐久性試験を行った。
試験には、市販の非磁性一成分現像方式のプリンター(HL-3040CN)を用いた。現像装置のトナーカートリッジに、トナーを充填した後、常湿常湿(N/N)環境下(温度:23℃、湿度:50%)に24時間放置した。放置後、同環境において、白べた印字を1枚行い、白度計(日本電色社製)を用いて白べた印字物の紙面上の白度を測定し、下記式により、カブリ濃度を算出した。
(印字前の白度)-(白べた印字物の白度)=(カブリ濃度)
現像装置のトナーカートリッジに、トナーを充填した後、高温高湿(H/H)環境下(温度:35℃、湿度:80%)に24時間放置した後、その環境下でカブリを測定した以外は、常温常湿(N/N)環境下におけるカブリ試験と同様にしてカブリ濃度を算出した。
トナーを低温低湿(L/L)環境下(温度10℃、湿度20%RH)に1日放置した後、上記カブリ試験で使用したプリンター(HL-3040CN)を用いて、2×2ドットライン(幅約85μm)で連続して線画像を形成し、10,000枚まで印字を行った。
印字500枚毎に、印字評価システム(YA-MA社製、商品名「RT2000」)によって測定し、線画像の濃度分布データを採取した。
常温常湿(N/N)環境下(温度:23℃、湿度:50%)の細線の線画像の線幅を評価の基準とする。評価方法としては、低温低湿(L/L)環境下における濃度の最大値の半値における全幅を線幅として、当該線幅と上記基準となる線幅との差が10μm以下のものは、1枚目の線画像を再現しているとして◎と評価する。当該線幅の差が10μm以上、20μm以下を維持できるものについては○と評価する。20μmを超えるものについては×と評価する。
印字耐久性試験には、市販の非磁性一成分現像方式のプリンター(HL-3040CN)を用い、現像装置のトナーカートリッジに、トナーを充填した後、印字用紙をセットした。
常温常湿(N/N)環境下(温度:23℃、湿度:50%)で、24時間放置した後、同環境下にて、5%印字濃度で10,000枚まで連続印刷を行った。500枚毎に、黒ベタ印字(印字濃度100%)を行い、反射式画像濃度計(マクベス社製、商品名:RD918)を用いて黒ベタ画像の印字濃度を測定した。さらに、その後、白ベタ印字(印字濃度0%)を行い、白ベタ印字の途中でプリンターを停止させ、現像後の感光体上における非画像部のトナーを、粘着テープ(住友スリーエム社製、商品名:スコッチメンディングテープ810-3-18)に付着させた後、剥ぎ取り、それを印字用紙に貼り付けた。次に、その粘着テープを貼り付けた印字用紙の白色度(B)を、白色度計(日本電色社製、商品名:ND-1)で測定し、同様にして、未使用の粘着テープだけを印字用紙に貼り付け、その白色度(A)を測定し、この白色度の差(B-A)をカブリ値(%)とした。この値が小さいほど、カブリが少なく良好であることを示す。
印字濃度が1.3%以上で、且つカブリ値が3%以下の画質を維持できる連続印刷枚数を調べた。
なお、表II-2中、「10000<」とあるのは、10,000枚の時点においても、印字濃度が1.3%以上で、且つカブリ値が3%以下の画質を維持できたことを示す。
まず、比較例II-1のトナーについて検討する。比較例II-1のトナーは、常温常湿(N/N)環境下におけるカブリ濃度が0.7、常温常湿(N/N)環境下におけるカブリ発生枚数が10,000枚を超える結果となり、少なくとも常温常湿(N/N)環境下における印字耐久性に問題は見られない。
しかし、比較例II-1のトナーの高温高湿(H/H)環境下におけるカブリ濃度は3.2であり、この結果は、実施例II-1~II-6、及び比較例II-1のトナー中、最も高いカブリ濃度である。また、低温低湿(L/L)環境下における細線再現性の評価は、比較例II-1のトナーのみが×であった。
これらの結果から、樹脂微粒子の表面が無機成分で被覆されているコアシェル型複合微粒子を外添剤として含有しない比較例II-1のトナーは、高温高湿(H/H)環境下における印字耐久性及び低温低湿(L/L)環境下における細線再現性に劣ることが分かる。
Claims (7)
- 結着樹脂及び着色剤を含有する着色樹脂粒子、並びに外添剤を含有する静電荷像現像用トナーであって、
前記外添剤が、樹脂微粒子の表面がシリカ、アルミナ、チタニア、及びジルコニアからなる群より選ばれる少なくとも1つの無機成分で被覆されているコアシェル型複合微粒子であり、且つ当該コアシェル型複合微粒子の全体積を100体積%としたときの、当該コアシェル型複合微粒子の無機成分の体積比率が45~75体積%であることを特徴とする、静電荷像現像用トナー。 - 前記コアシェル型複合微粒子の吸着水分量が0.5~2.5質量%であることを特徴とする、請求の範囲第1項に記載の静電荷像現像用トナー。
- 前記コアシェル型複合微粒子の添加量が、前記着色樹脂粒子100質量部に対して0.1~2.0質量部であることを特徴とする、請求の範囲第1項又は第2項に記載の静電荷像現像用トナー。
- 前記着色樹脂粒子の体積平均粒径が4~12μmであり、且つ平均円形度が0.96~1.00であることを特徴とする、請求の範囲第1項乃至第3項のいずれか一項に記載の静電荷像現像用トナー。
- 前記着色樹脂粒子及び前記コアシェル型複合微粒子がいずれも正帯電性を示すことを特徴とする、請求の範囲第1項乃至第4項のいずれか一項に記載の静電荷像現像用トナー。
- 前記コアシェル型複合微粒子の個数平均粒径が30~300nmであることを特徴とする、請求の範囲第1項乃至第5項のいずれか一項に記載の静電荷像現像用トナー。
- 前記コアシェル型複合微粒子の前記樹脂微粒子が架橋樹脂であることを特徴とする、請求の範囲第1項乃至第6項のいずれか一項に記載の静電荷像現像用トナー。
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US8846285B2 (en) | 2014-09-30 |
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