JP4277626B2 - Toner for electrophotography and image forming apparatus using the toner - Google Patents

Description

  The present invention relates to a toner used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, etc., and forming an image by thermal fixing, a method for producing the toner, and image formation using the toner Relates to the device.

  Generally, toner for electrostatic image formation uses toner fine particles made of a binder resin containing a coloring component such as a pigment or dye and, if necessary, a charge control agent, as a toner mother particle, and the outside (surface) of the toner mother particle. In addition, for the purpose of imparting fluidity or controlling chargeability, it is manufactured by a method of adding an external additive. As the external additive, positively charged silica fine particles, negatively chargeable silica fine particles, inorganic fine particles other than silica (such as titanium oxide), metal soap (fatty acid metal salt) and the like are used.

  Among these, metal soaps are attracting attention for their binding properties, and are often used as external additives in toners as disclosed in, for example, Patent Documents 1 to 7. Patent Document 1 discloses a hydrophobic silica fine particle or hydrophobic titania as a first component, a hydrophobic silica fine particle or hydrophobic titania having a particle size larger than the first component as a second component, an inorganic fine particle as a third component, and a fatty acid metal. A method is disclosed in which salt is used as the fourth component, and these first to fourth components are externally added to the toner base particles at the same time, or the first component is finally added externally. In Patent Document 1, a fatty acid metal salt is added from the viewpoint of preventing sticking of the surface of the photoreceptor and prevention of black spot generation, and thereafter, hydrophobic silica or hydrophobic titania is added. However, hydrophobic silica or hydrophobic titania, which is an external additive, is easily released from the toner surface, and the charging stability over a long period of time cannot be maintained and the fluidity of the toner is reduced. There is a problem that a decrease, a decrease in image density, and the like occur.

  In Patent Document 2, silica having an amino group on the surface and a fatty acid metal salt are simultaneously added to obtain a toner by one external addition treatment. In the toner obtained by this method, the liberation rate of hydrophobic silica is slightly improved, but there remains a problem that the charge amount of the toner cannot be stably maintained. Patent Documents 3 to 7 also describe that a fatty acid metal salt is externally added when preparing a toner. In these Patent Documents 3 to 7, as in Patent Document 2, the fatty acid metal salt is added simultaneously with other external additives, and the toner is obtained by one external addition process. The toners described in Patent Documents 3 to 7 still have a problem that the charge amount of the toner cannot be stably maintained.

JP 2001-100452 A Japanese Patent No. 2502353 Japanese Patent Publication No. 8-33681 Japanese Patent No. 2759510 Japanese Patent Laid-Open No. 9-114129 JP-A-11-323396 JP 2001-296688 A JP 2002-202622 A

  An object of the present invention is to provide a toner that is excellent in charge uniformity, maintains charge stability for a long period of time even in repeated use, has high fluidity and transfer efficiency, and does not decrease image density.

  The present invention includes a step of adding titanium oxide fine particles to toner base particles containing a binder resin and a colorant; then, particles having a long chain fatty acid or a salt thereof have a higher share than the share at the time of adding the titanium oxide fine particles. A toner obtained by performing the steps of adding in this order is provided.

  The present invention also includes a step of adding titanium oxide fine particles and negatively-charged silica fine particles as external additives to toner base particles containing a binder resin and a colorant; A toner obtained by performing in this order the steps of adding at a share higher than the share at the time of external additive addition.

  In a preferred embodiment, the negatively chargeable silica fine particles and the titanium oxide fine particles are simultaneously added to the toner base particles.

  In another preferred embodiment, the step of adding the titanium oxide fine particles and the negatively chargeable silica fine particles as external additives comprises first adding the negatively chargeable silica fine particles to the toner base particles, and then the titanium oxide fine particles. Consisting of adding.

  In a preferred embodiment, the addition of the titanium oxide fine particles, the negatively chargeable silica fine particles, and the long chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and the rotational speed of the rotor blade is controlled. By this, the share at the time of addition of the particle | grains which consist of a long chain fatty acid or its salt is raised.

  In another preferred embodiment, the addition of the titanium oxide fine particles, the negatively-charged silica fine particles and the particles composed of long-chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and the rotor blade and the mixer By controlling the distance from the wall, the share at the time of adding particles comprising a long-chain fatty acid or a salt thereof can be increased.

  The present invention also includes a step of adding titanium oxide fine particles to toner base particles containing a binder resin and a colorant; then, the particles made of long-chain fatty acids or salts thereof are higher in share than when the titanium oxide fine particles are added. A method for producing a toner comprising the steps of adding in a share;

  Another aspect of the present invention is a step of adding titanium oxide fine particles and negatively chargeable silica fine particles as external additives to toner base particles containing a binder resin and a colorant; A method for producing a toner is provided, which includes a step of adding in a share higher than the share at the time of adding an external additive.

  In a preferred embodiment, the negatively chargeable silica fine particles and the titanium oxide fine particles are simultaneously added to the toner base particles.

  In another preferred embodiment, the step of adding the titanium oxide fine particles and the negatively chargeable silica fine particles as external additives includes first adding the negatively chargeable silica fine particles to the toner base particles, and then adding the titanium oxide fine particles. Consists of.

  In a preferred embodiment, the addition of the titanium oxide fine particles, the negatively chargeable silica fine particles and the long chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and the rotational speed of the rotor blade is adjusted. By controlling, the share at the time of the addition of particles comprising a long chain fatty acid or a salt thereof is increased.

  In another preferred embodiment, the addition of the titanium oxide fine particles, the negatively-charged silica fine particles and the particles composed of long-chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and the rotor blade and the mixer By controlling the distance from the wall, the share at the time of adding particles comprising a long-chain fatty acid or a salt thereof can be increased.

  The present invention also provides an image forming apparatus comprising any one of the above toners.

  In a preferred embodiment, the image forming apparatus includes a latent image carrier on which an electrostatic latent image is formed; and transports toner to the latent image carrier to develop the electrostatic latent image on the latent image carrier. And a developer having a toner regulating member that regulates the amount of toner conveyed from the toner carrier to the latent image carrier.

  The toner of the present invention is obtained by first adding titanium oxide fine particles to toner base particles, and finally adding particles consisting of long-chain fatty acid or a salt thereof with a share higher than the share at the time of adding the titanium oxide fine particles. Toner. Further, in the toner of the present invention, titanium oxide fine particles and negatively chargeable silica fine particles are added to the toner base particles, and then the particles composed of long chain fatty acids or salts thereof are more than the share at the time when these external additives are added. It is obtained by adding with a high share. Finally, the long chain fatty acid or a salt thereof acts as a binder for the titanium oxide fine particles and the negatively charged silica fine particles by adding particles of the long chain fatty acid or a salt thereof with a high share. Therefore, it is considered that these external additive fine particles are prevented from being detached from the toner surface. Further, by adding fine particles comprising a long-chain fatty acid or a salt thereof at the end, the effect as a toner lubricant is further exerted, preventing the toner from agglomerating, and external particles such as titanium oxide fine particles by friction between the toners. It is considered that the additive is prevented from being embedded in the toner base particles, and the charging uniformity is maintained. Furthermore, charging stability is maintained even when the toner is used repeatedly. Also, in the developing unit, contact between the toner and the photoreceptor causes the long-chain fatty acid or a salt thereof to migrate to the photoreceptor surface, lubricate the photoreceptor surface, and the photoreceptor is polished by an external additive on the toner surface. Can be prevented.

  In the present specification, external additives or external additives are added to toner base particles such as titanium oxide fine particles, negatively charged silica fine particles, long chain fatty acid or a salt thereof, and positively charged silica fine particles. Addition of these external additives (external additives) to the outside (surface) of the toner base particles is called external addition.

  First, (i) toner base particles and materials constituting the toner base particles (binder resin and colorant, release agent, dispersant, charge control agent, magnetic agent, etc.), which are materials used in the present invention. Internal additives), (ii) titanium oxide fine particles, (iii) negatively chargeable silica fine particles, and (iv) long-chain fatty acids or salts thereof, and other necessary additions (v) positively chargeable silica fine particles, (Vi) The inorganic fine particles will be described, and then the toner of the present invention will be described.

(I) Materials used in the present invention (i) Toner base particles The toner base particles include a binder resin and a colorant, and include a release agent, a dispersant, a charge control agent, a magnetic agent, etc. as necessary. Contains additives. The toner base particles are positively or negatively charged, and preferably negatively charged. There are several methods for charging the toner base particles so as to have a negative charge amount in an appropriate range. For example, a negative charge control agent is blended with a positively chargeable binder resin, and if the chargeability of the negatively chargeable resin is insufficient, a negative charge control agent is further blended, or the binder resin itself is negatively charged. For example, there is a method of making a functional resin. Hereinafter, the material constituting the toner base particles and the method for producing the toner base particles will be sequentially described.

(i-1) Material composing toner mother particles (binder resin)
As the binder resin, a resin generally used as a toner is used. Examples of such binder resins include polystyrene resins, acrylate resins or methacrylate resins (hereinafter referred to as (meth) acrylate resins), styrene-acrylic resins, polyester resins, polyethylene resins, epoxy resins, Silicone resin, polypropylene resin, fluororesin, polyamide resin, polyvinyl alcohol resin, polyurethane resin, polyvinyl butyral resin, and a copolymer containing components of these resins are used.

  Of these, polystyrene resins and styrene- (meth) acrylate resin copolymers are preferably used.

  Examples of polystyrene resins include hydrogenated styrene resins, styrene-isobutylene copolymers, acrylonitrile-butadiene-styrene copolymers (ABS resins), acrylonitrile-styrene copolymers (AS resins), acrylonitrile-polyethylene chloride-styrene. Copolymer (ACS resin), styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene crosslinked polymer, styrene-butadiene-chlorinated paraffin copolymer, styrene-allyl alcohol copolymer, Examples thereof include styrene-butadiene rubber, styrene-maleic ester copolymer, styrene-isobutylene copolymer, and styrene-maleic anhydride copolymer.

  Examples of the styrene- (meth) acrylate resin copolymer include acrylate-styrene-acrylonitrile copolymer (ASA resin), styrene-diethylamino-ethyl methacrylate copolymer, styrene-methyl methacrylate copolymer, styrene. -N-butyl methacrylate copolymer, styrene-methyl methacrylate-n-butyl acrylate copolymer, styrene-methyl methacrylate-butyl allylate-N- (ethoxymethyl) acrylamide copolymer, styrene-glycidyl methacrylate copolymer Polymer, styrene-butadiene-dimethylaminoethyl methacrylate copolymer, styrene-acrylic acid ester-maleic acid ester copolymer, styrene-methyl methacrylate-acrylic acid 2-ethylhexyl Copolymer, styrene-n-butylarylate-ethyl glycol methacrylate copolymer, styrene-n-butyl methacrylate-acrylic acid copolymer, styrene-n-butyl methacrylate-maleic anhydride copolymer, styrene- Examples thereof include butyl acrylate-isobutyl maleic acid half ester-divinylbenzene copolymer, styrene-butadiene-acrylate copolymer, and styrene-acrylate copolymer.

  The mass average molecular weight of the binder resin used in the present invention is not particularly limited, but is usually preferably 2,000 to 30,000, more preferably 4,000 to 25,000, and 6,000 to 20,000. More preferably, it is 000. When the molecular weight is less than 2,000, the viscosity at the time of kneading is lowered, and there is a possibility that the colorant cannot be sufficiently dispersed. Therefore, the saturation or transparency of the obtained toner may be reduced. When the molecular weight is larger than 30,000, the viscosity becomes too high, and the colorant cannot be sufficiently dispersed, and the saturation or transparency of the toner may be lowered. The binder resin may be a mixture of a plurality of resins having a molecular weight within the above range.

  The molecular weight of the binder resin is measured by gel permeation chromatography (GPC).

  When fixing the toner in image formation by the thermal fixing method, the flow softening point (Tm) of the binder resin is preferably low. For example, Tm is preferably 85 to 140 ° C, more preferably 90 to 120 ° C, and further preferably 100 to 110 ° C. The glass transition temperature (Tg) of the binder resin is preferably 40 to 90 ° C, more preferably 50 to 80 ° C. In addition, the flow softening point (Tm) was measured under the following conditions using “Flow Tester CFT-500D” manufactured by Shimadzu Corporation as a sample by pressure-molding 1.0 g of a binder resin into a pellet. To do. Temperature rising rate 5 ° C./min; cylinder pressure 2.0 MPa; die hole diameter 1.0 mm; die hole length 1.0 mm; Tm calculation method 1/2 method. Further, the glass transition temperature (Tg) of the binder resin is measured under the following conditions using 10 mg of the binder resin packed in an aluminum cell and using “DSC120” manufactured by Seiko Instruments Inc. Measurement temperature 0 to 200 ° C .; temperature increase rate 10 ° C./min: Read from DSC curve at the second temperature increase.

  When the toner is fixed by the pressure fixing method, a wax-like resin is preferably used as the binder resin. Examples of the wax-like resin include polyethylene resins, polyethylene-vinyl acetate copolymers, and natural waxes among the above binder resins.

  The binder resin is produced by a polymerization method such as emulsion polymerization, dispersion polymerization, suspension polymerization, or a pulverization method including kneading, pulverization, and classification steps. Considering the uniformity or fluidity of the finally obtained toner particles, the binder resin is preferably a resin obtained by a polymerization method.

  Moreover, the said binder resin may be used independently and may blend and use 2 or more types. Needless to say, the binder resin is an example, and is not limited thereto.

(Coloring agent)
As the colorant, organic pigments, inorganic pigments, and dyes as shown below can be used. Among organic and inorganic pigments, carbon black, copper oxide, iron tetroxide, manganese dioxide, aniline black, activated carbon, etc. are used as the black pigment.

  Yellow pigments include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, hansa yellow, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow. NCG, tartrazine lake, etc. are used.

  As the orange pigment, red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GKM and the like are used.

  Red pigments include Bengala, Cadmium Red, Red Plum, Mercury Sulfide, Cadmium, Permanent Red 4R, Risor Red, Pyrozolone Red, Watching Red, Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B Alizarin lake, Brilliant Carmine 3B, etc. are used.

  As the purple pigment, manganese purple, fast violet B, methyl violet lake and the like are used. As the blue pigment, bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indanthrene blue BC, and the like are used.

  As the green pigment, chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green G, or the like is used.

  As the white pigment, zinc white, titanium oxide, antimony white, zinc sulfide and the like are used.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white.

  As the dye, basic dyes, acid dyes, disperse dyes, direct dyes, and the like are used. Examples of such dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

  When the present invention is a translucent color toner, the following various pigments and dyes are used as the colorant.

  Examples of yellow pigments include CI10316 (Naphthol Yellow S), CI11710 (Hansa Yellow 10G), CI11660 (Hansa Yellow 5G), CI11670 (Hansa Yellow 3G), CI11680 (Hansa Yellow G), CI11730 (Hansa Yellow GR), CI11735 (Hansa Yellow A), CI11740 (Hansa Yellow NR), CI12710 (Hansa Yellow R), CI12720 (Pigment Yellow L), CI21090 (Benzidine Yellow), CI21095 (Benzidine Yellow G), CI21100 (Benzidine Yellow GR), CI20040 (Permanent Yellow NCG), CI21220 (Vulcan Fast Yellow 5), CI21135 (Vulcan Fast Yellow R), etc. are used.

  Red pigments include CI12055 (Starlin I), CI12075 (Permanent Orange), CI12175 (Risor Fast Orange 3GL), CI12305 (Permanent Orange GTR), CI11725 (Hansaero 3R), CI21165 (Vulcan Fast Orange GG) ), CI21110 (Benzidine Orange G), CI12120 (Permanent Red 4R), CI1270 (Paral Red), CI12085 (Fire Red), CI12315 (Brilliant Fast Scarlet), CI12310 (Permanent Red F2R), CI12335 ( Permanent Red F4R), CI12440 (Permanent Red FRL), CI12460 (Permanent Red FRLL), CI12420 (Permanent Red F4RH), CI12450 (Light Fast Red Toner B), CI12490 (Permanent Carmine FB), CI15850 ( Brilliantka Min 6B) and the like can be used.

  As the blue pigment, C.I.74100 (metal-free phthalocyanine blue), C.I.74160 (phthalocyanine blue), C.I.74180 (first sky blue), or the like is used.

  These colorants can be used alone or in combination of two or more, but it is desirable to use 1 to 20 parts by mass, preferably 2 to 10 parts by mass with respect to 100 parts by mass of the binder resin. When the amount is more than 20 parts by mass, the toner fixing property and transparency are deteriorated. On the other hand, when the amount is less than 1 part by mass, a desired image density may not be obtained.

(Release agent)
Release agents include paraffin wax, polyolefin wax, modified wax having aromatic group, hydrocarbon compound having alicyclic group, natural wax, long chain fatty acid having 12 or more carbon atoms or ester thereof, long chain fatty acid metal Salts (metal soaps), fatty acid amides, fatty acid bisamides and the like are used. Of the release agents, paraffin wax, polyolefin wax and metal soap are preferably used.

  Examples of the paraffin wax include paraffin wax (manufactured by Nippon Oil Co., Ltd. or Nippon Seiwa Co., Ltd.), micro wax (manufactured by Nippon Oil Co., Ltd.), and microcrystalline wax (manufactured by Nippon Seiwa Co., Ltd.). , Hard paraffin wax (manufactured by Nippon Seiwa Co., Ltd.), PE-130 (manufactured by Hoechst), Mitsui High Wax 110P (manufactured by Mitsui Petrochemical Co., Ltd.), Mitsui High Wax 220P (manufactured by Mitsui Petrochemical Co., Ltd.), Mitsui High Wax 660P (Mitsui Petrochemical Co., Ltd.), Mitsui High Wax 210P (Mitsui Petrochemical Co., Ltd.), Mitsui High Wax 320P (Mitsui Petrochemical Co., Ltd.), Mitsui High Wax 410P (Mitsui Petrochemical) ), Mitsui High Wax 420P (Mitsui Petrochemical Co., Ltd.), modified wax JC-1141 (Mitsui Petrochemical Co., Ltd.), modified wax JC-2130 (Mitsui Petrochemical Co., Ltd.), Modified wack JC-4020 (Mitsui Petrochemical Co., Ltd.), modified wax JC-1142 (Mitsui Petrochemical Co., Ltd.), modified wax JC-5020 (Mitsui Petrochemical Co., Ltd.), beeswax, carnauba wax, Montan A wax etc. can be mentioned.

  Examples of the polyolefin wax include low molecular weight polypropylene, low molecular weight polyethylene, oxidized polypropylene, oxidized polyethylene, and the like. Specific examples of polyolefin waxes include, for example, Hoechst Wax PE520, Hoechst Wax PE130, Hoechst Wax PE190 (manufactured by Hoechst), Mitsui High Wax 200, Mitsui High Wax 210, Mitsui High Wax 210M, Mitsui High Wax 220, Mitsui High Wax Non-oxidized polyethylene wax such as 220M (Mitsui Petrochemical Industries), Sun Wax 131-P, Sun Wax 151-P, Sun Wax 161-P (Sanyo Chemical Industries), Hoechst Wax PED121, Hoechst Wax PED153, Hoechst Wax PED521, Hoechst Wax PED522, Ceridust 3620, Ceridust VP130, Ceridust VP5905, Ceridust VP9615A, Ceridust TM9610F, Ceridust 3715 (manufactured by Hoechst), Mitsui High Wax 420M Koe Industries Co., Ltd.), Sun Wax E-300, Sun Wax E-250P (Sanyo Kasei Kogyo Co., Ltd.) and other oxidized polyethylene waxes, Hoechi Non-oxidized polypropylene wax such as st Wachs PP230 (Hoechst), Viscol 330-P, Biscol 550-P, Biscol 660P (Sanyo Chemical Industries), and Biscol TS-200 (Sanyo Chemical Industries, Ltd.) Oxidized polypropylene wax, such as

  As the long chain fatty acid metal salt (metal soap), zinc stearate, calcium stearate, magnesium stearate, zinc oleate, zinc palmitate, magnesium palmitate and the like are preferably used.

  These release agents can be used alone or in combination. As the release agent, a compound having a low softening point (melting point) is preferable, and those having a softening point of 40 to 130 ° C, preferably 50 to 120 ° C are preferably used. The softening point is represented by an endothermic main peak value in a DSC endothermic curve measured by “DSC120” manufactured by Seiko Instruments Inc.

(Dispersant)
As the dispersant, metal soap, polyethylene glycol, or the like is used.

(Charge control agent)
The charge control agent is used as necessary to control the chargeability of the toner base particles. When the negative chargeability of the binder resin itself is low, or when the binder resin itself is positively charged, a negative charge control agent is used to make the entire toner base particles have a desired level of negative chargeability. To have.

  Examples of the negative charge control agent include metal salts or metal complexes of salicylic acid derivatives, metal salts of benzylic acid derivatives, and phenylborate quaternary ammonium salts. As the metal salts of salicylic acid derivatives or benzylic acid derivatives, these zinc salts, nickel salts, copper salts, chromium salts and the like are preferably used.

  Examples of commercially available negative charge control agents include oil black (Color Index 26150), oil black BY (manufactured by Orient Chemical Co., Ltd.), Bontron S-22 (manufactured by Orient Chemical Co., Ltd.), and salicylic acid metal complex E. -81 (produced by Orient Chemical Co., Ltd.), thioindigo pigment, sulfonylamine derivative of copper phthalocyanine, Spiron Black TRH (produced by Hodogaya Chemical Co., Ltd.), Bontron S-34 (produced by Orient Chemical Co., Ltd.) ), Nigrosine SO (manufactured by Orient Chemical Industry Co., Ltd.), Ceres Schwartz (R) G (manufactured by Farben Fabricen Bayer), Chromogen Schwarz ETOO (CINO.14645), Azo Oil Black (R) (National Aniline). Among these, salicylic acid metal complex E-81 is preferably used. These negative charge control agents can be used alone or in combination.

  The negative charge control agent is preferably blended in the binder resin so that the charge amount of the toner base particles is −5 to −60 μC / g. Therefore, although the addition amount with respect to binder resin is determined by the binder resin to be used, generally it mix | blends in 0.1-5 mass parts with respect to 100 mass parts of binder resin.

  The positive charge control agent is internally added to the negative charge resin as necessary to adjust the negative charge amount of the toner base particles. A commercially available positive charge control agent is used as the positive charge control agent. For example, Nigrosine Base EX (manufactured by Orient Chemical Industries, Ltd.), quaternary ammonium salt P-51 (manufactured by Orient Chemical Industries, Ltd.), Nigrosine Bontron N-01 (manufactured by Orient Chemical Industries, Ltd.), Sudan Chief Examples include Schwartz BB (Solvent Black 3: Color Index 26150), Fett Schwartz HBN (CI NO. 26150), Brilliant Spirits Schwarz TN (manufactured by Farben Fabricken Bayer), and Zabon Schwartz X (manufactured by Farberge Hoechst). Of these, the quaternary ammonium salt P-51 is preferably used. In addition to the above, alkoxylated amines, alkylamides, molybdate chelate pigments and the like are also used as positive charge control agents. These positive charge control agents can be used alone or in combination.

(Magnetic agent)
Examples of the magnetic agent include metal powders such as Fe, Co, Ni, Cr, Mn, and Zn, metal oxides such as Fe ₃ O ₄ , Fe ₂ O ₃ , Cr ₂ O ₃ , and ferrite, and manganese and acid. Examples include alloys that exhibit ferromagnetism by heat treatment of the alloys. These may be pretreated with a coupling agent or the like.

(i-2) Manufacture of toner base particles Toner base particles are added to the binder resin with the colorant and, if necessary, internal additives such as a release agent, a dispersant, a charge control agent, and a magnetic agent. And manufactured. For example, a method for producing toner base particles by a pulverization method including a kneading, pulverization, and classification process will be described. First, a predetermined amount of additives such as a binder resin, a colorant, and a release agent are charged into a mixer such as a Henschel mixer 20B (Mitsui Mining Co., Ltd.) and mixed uniformly. The mixing ratio of additives such as a binder resin, a colorant, a charge control agent, and a release agent is appropriately determined in consideration of the color of the toner, chargeability, and the like.

  Next, the above mixture is put into a twin-screw kneading extruder (PCM-30 manufactured by Ikekai Kasei Co., Ltd.) and uniformly melt-kneaded. Other melt kneading means include batch-types such as continuous kneaders such as “TEM-37” (Toshiba Machine Co., Ltd.), “KRC Kneader” (Kurimoto Iron Works Co., Ltd.), and heating / pressure kneaders. Examples thereof include a kneader. The obtained melt-kneaded product is finely pulverized using a pulverizing means to obtain toner mother particles having a desired average particle size. The pulverization may be performed by, for example, a mechanical pulverizer turbo mill (Kawasaki Heavy Industries, Ltd.) in addition to collision pulverization using jet air using a jet pulverizer 200AFG (Hosokawa Micron Corporation) or IDS-2 (Nippon Pneumatic Industrial Co., Ltd.). )), Super Rotor (Nisshin Engineering Co., Ltd.), etc.

  Next, the particle size of the obtained toner base particles is adjusted using, for example, wind power or rotor rotation. For example, when the air classifier 100ATP (Hosokawa Micron Co., Ltd.), DSX-2 (Nippon Pneumatic Industrial Co., Ltd.), Elbow Jet (Nittetsu Mining Co., Ltd.) or the like is used, a sharp particle size distribution is obtained.

  The toner base particles are also a method in which an internal additive such as a resin and a colorant constituting the toner base particles is dissolved in an organic solvent, dispersed and granulated with a classifier and an emulsifier in an aqueous solvent, and separated and dried. You may produce by.

  The charge amount of the toner base particles is preferably −5 to −60 μC / g. When the charge amount is smaller than this range, toner leakage from the developing device becomes severe, and when it is larger than −60 μC / g, it is necessary to apply an excessive development bias in order to obtain a sufficient image density. Problem arises.

The charge amount of the toner base particles is measured as follows, for example. In an environment of 25 ° C. and 45% RH, 0.03 g of toner base particles and 0.97 g of ferrite carrier are mixed in a 20 ml polyethylene container and stirred at 100 rpm for 15 minutes to charge the toner base particles. Thereafter, 0.3 g of this mixture is sampled, and nitrogen gas having a pressure of 0.3 kg / cm ² is blown onto the mixture of the toner base particles and the carrier to separate the toner base particles and the ferrite carrier. Next, the charge amount (Q / m) for each toner is measured to measure the charge amount of the toner base particles. For the measurement of the charge amount, for example, an E-SPART analyzer manufactured by Hosokawa Micron Corporation is used.

(Ii) Titanium oxide (titania) fine particles In the present invention, the titanium oxide fine particles are used as necessary for adjusting the charge of the toner. There is no restriction | limiting in particular in the titanium oxide fine particle used by this invention. Fine particles of titanium oxide having a relatively low electrical resistivity are preferably used. Titanium oxide can take crystal forms such as rutile, anatase, and rutile-anatase. Any crystalline titanium oxide may be used, but the rutile-anatase type titanium oxide is easy to adjust the charge, and even if the number of printed sheets increases, the titanium oxide particles are not easily embedded in the toner base particles. It is preferably used in terms of

  Although there is no restriction | limiting in particular in the magnitude | size of a titanium oxide microparticle, It is preferable that a particle size or the magnitude | size of a major axis is a magnitude | size of 10-30 nm. In the case of rutile-anatase type titanium oxide, titanium oxide fine particles having a major axis of about 10 to 30 nm are preferable.

  The titanium oxide fine particles are added in an amount of 0.2 to 2.0 parts by weight, preferably 0.3 to 1.5 parts by weight, based on 100 parts by weight of the toner base particles.

  The surface of the fine particles of titanium oxide is hydrophobic in order to reduce the change in chargeability with respect to changes in the external environment of the toner (that is, maintain stable chargeability) and improve the fluidity of the toner. It is preferable. Hydrophobization of the titanium oxide fine particles is carried out by the same method as that of the negatively chargeable silica fine particles.

  As the hydrophobic titanium oxide fine particles, STT-30S manufactured by Titanium Industry Co., Ltd. is used.

(Iii) Negatively chargeable silica fine particles The negatively chargeable silica fine particles used in the present invention are not particularly limited. As the negatively chargeable silica fine particles, generally, negatively chargeable silica fine particles having an average particle diameter of 4 to 120 nm, preferably 5 to 50 nm, and more preferably 6 to 40 nm are used. The smaller the average particle size of the negatively chargeable silica fine particles, the higher the fluidity of the obtained toner. If it is smaller than 4 nm, the toner may be buried in the toner base particles. If it exceeds 120 nm, the fluidity may be extremely deteriorated. In this specification, the average particle diameter of fine particles such as negatively chargeable silica, toner base particles, and toner particles means a volume average particle diameter unless otherwise specified.

  As the negatively chargeable silica fine particles, negatively chargeable silica fine particles having a uniform particle diameter may be used alone, but it is preferable to use two or more negatively chargeable silica fine particles having different average particle diameters in combination. Generally, negatively-charged silica fine particles (small particle size silica) having a small average particle size are used, and this is used in combination with negatively-charged silica fine particles (large particle size silica) having a large average particle size. As a result, the absolute value of the charge amount can be increased as compared with the case where only small particle size silica is used, and the large particle size silica becomes resistance, and the small particle size silica is embedded in the toner base particles. Therefore, the long-term charging stability is improved. Furthermore, it is possible to improve the fluidity of the toner, exhibit a blocking effect against heat, and improve the storage stability of the toner. Preferably, the negatively-charged silica fine particles having an average particle size of 5 to 20 nm, preferably 6 to 15 nm as a small particle size silica, and a negative particle having an average particle size of 20 to 50 nm, preferably 20 to 40 nm, as a large particle size silica. It is preferable to use chargeable silica fine particles. The difference in average particle size between the large particle size silica and the small particle size silica is preferably 10 nm or more, and more preferably 20 nm or more.

  The addition ratio of large particle size silica to small particle size silica is 1: 3 to 3: 1, preferably 1: 2 to 2: 1, more preferably 1: 1.5 to 1.5: by weight. A value of 1 is preferable for imparting fluidity to the toner and obtaining long-term charging stability.

  In the case of using large particle size silica and small particle size silica, these may be mixed and added at the same time during the production described below, either one may be added first, and then the other may be added. .

  The addition amount of the negatively chargeable silica fine particles can vary depending on the particle size distribution or fluidity of the toner base particles, or the particle size distribution of the external additive, the desired charge amount, and the like. For example, in the case of silica having the small particle diameter, 0.5 to 2.0 parts by mass, preferably 0.7 to 1.5 parts by mass are added to 100 parts by mass of the toner base particles. In the case of a large particle size silica, 0.2 to 2.0 parts by mass, preferably 0.3 to 1.5 parts by mass is added. When the large particle size silica and the small particle size silica are used in combination, the total amount is 0.5 to 3.0 parts by mass, preferably 0.7 with respect to 100 parts by mass of the toner base particles, taking the above mixing ratio into consideration. Add ~ 2.5 parts by weight.

  The negatively chargeable silica fine particles are preferably hydrophobized. By making the surface of the negatively chargeable silica fine particles hydrophobic, the fluidity and chargeability of the toner are further improved. Hydrophobization of silica fine particles can be achieved by using silane compounds such as aminosilane, hexamethyldisilazane and dimethyldichlorosilane; or dimethylsilicone, methylphenylsilicone, fluorine-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, etc. This silicone oil is used, for example, by a method commonly used by those skilled in the art, such as a wet method or a dry method.

  As the hydrophobic negatively chargeable silica fine particles, commercially available RX200 and RX50 manufactured by Nippon Aerosil Co., Ltd., TG811F, TG810G and TG308F manufactured by Cabot Corp. are used.

(Iv) Long chain fatty acid or salt thereof The long chain fatty acid or salt thereof used in the present invention is not particularly limited. As the long chain fatty acid, a long chain fatty acid having preferably 10 to 30 carbon atoms, more preferably 12 to 28 carbon atoms, and still more preferably 12 to 18 carbon atoms is used. Examples of long chain fatty acids include long chain saturated fatty acids and long chain unsaturated fatty acids. Long chain saturated fatty acids are preferably used. The long-chain fatty acid may have a branch, but a linear saturated fatty acid such as stearic acid is preferably used.

  The long chain fatty acid is preferably used in the form of a salt, and more preferably in the form of a metal salt (so-called metal soap). Although there is no restriction | limiting in particular as a metal salt of a long chain fatty acid, For example, calcium salt, zinc salt, magnesium salt, aluminum salt, lithium salt etc. are mentioned. Examples of the metal soap include magnesium stearate, calcium stearate, zinc stearate and the like, and these particles are preferably used. The particles comprising a long-chain saturated fatty acid or a salt thereof may be used alone or in combination of two or more.

  The long-chain fatty acid or a salt thereof, particularly a long-chain fatty acid metal salt (metal soap), preferably has a volume average particle diameter or major axis diameter of 0.5 to 10 μm, and more preferably 1 to 5 μm. If the average particle diameter or the major axis diameter is out of this range, the effect as a binder, lubricant, flow aid, or toner aggregation preventing effect tends to be insufficient.

  The long-chain fatty acid or salt thereof, particularly metal soap, preferably has a melting point of about 100 to 150 ° C. from the viewpoint of heat resistance and lubricity. When the melting point is lower than 100 ° C., the heat resistance of the toner is lowered, and the toner may aggregate when stored in a high temperature environment. If it is higher than 150 ° C, the lubricating action may be reduced.

  As metal soaps, metal soaps manufactured by the direct method and metal soaps manufactured by the double decomposition method are known. It is preferable to adjust the particle size so that

  The particles comprising a long-chain saturated fatty acid or a salt thereof are added in an amount of 0.1 to 1.0 parts by weight, preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of toner base particles. When the addition amount is less than 0.1% by mass, the effects as the binder, the aggregation preventing effect, the flow aid, the lubricant and the like may not be sufficiently exhibited. On the other hand, when the addition amount is more than 1.0% by mass, the fluidity is inferior, the charge rising property is remarkably deteriorated, and noise such as fog may be generated.

(V) Positively Charged Silica Fine Particles In the present invention, the positively chargeable silica fine particles are used as necessary for adjusting the charge of the toner. The positively chargeable silica fine particles may be added after the addition of titanium oxide and negatively chargeable silica fine particles, before the addition of particles composed of long chain fatty acids or salts thereof, or simultaneously with the particles composed of long chain fatty acids or salts thereof. The negatively chargeable silica particles are preferably bonded to the toner base particles, and the effect of the long-chain fatty acid or a salt thereof as a binder and the effect as a lubricant are preferable.

  There are no particular limitations on the positively chargeable silica fine particles used as necessary in the present invention. The volume average particle diameter of the positively chargeable silica fine particles is preferably 10 to 50 nm, more preferably 15 to 40 nm in consideration of fluidity and the like.

  The positively charged silica fine particles are preferably subjected to a hydrophobic treatment. By making the surface of the positively chargeable silica fine particles hydrophobic, the change in the chargeability with respect to the change in the external environment of the toner is reduced (that is, the stable chargeability is maintained) and the fluidity of the toner is improved. Therefore, it is preferable. The hydrophobization of the positively chargeable silica fine particles is performed by the same method as the above-described hydrophobization of the negatively chargeable silica fine particles.

  As the hydrophobic positively chargeable silica fine particles, commercially available NA50H manufactured by Nippon Aerosil Co., Ltd., TG820F manufactured by Cabot Co., Ltd., etc. are used.

  The positively chargeable silica fine particles are added in an amount of 0.1 to 1.0 parts by weight, preferably 0.2 to 0.8 parts by weight, based on 100 parts by weight of the toner base particles, if necessary.

(Vi) Inorganic fine particles Inorganic fine particles other than titanium oxide fine particles can also be externally added for the purpose of controlling the chargeability and improving the fluidity. The inorganic fine particles other than the titanium oxide fine particles can also be added after the addition of the negatively chargeable silica fine particles and before the addition of the particles of the long chain fatty acid or a salt thereof. It is preferable for binding and exhibiting the effect of a long-chain fatty acid or a salt thereof as a binder and the effect of a lubricant.

For example, as inorganic fine particles, fine particles of metal oxides such as aluminum oxide, strontium oxide, tin oxide, zirconia oxide, magnesium oxide and indium oxide; fine particles of nitride such as silicon nitride; fine particles of carbide such as silicon carbide; calcium sulfate And fine particles of metal salts such as barium sulfate and calcium carbonate; and inorganic fine particles such as a composite thereof. Metal oxide fine particles having an electrical resistivity of 10 ⁹ Ωcm or less and a relatively low electrical resistivity are preferably used.

  Although there is no restriction | limiting in particular in the magnitude | size of the inorganic fine particle to add, It is preferable that a particle size is a magnitude | size of 10-30 nm. These inorganic fine particles are preferably subjected to a hydrophobic treatment on the surface for the purpose of stabilizing charging characteristics. For the hydrophobization treatment, the same method as any of the above-described hydrophobic methods for the negatively chargeable silica fine particles and the positively chargeable silica fine particles is employed.

(II) Toner of the Present Invention and Method for Producing the Same The toner of the present invention comprises toner base particles containing a binder resin and a colorant and titanium oxide fine particles alone or a combination of titanium oxide fine particles and negatively chargeable silica fine particles. And then adding particles comprising a long-chain fatty acid or a salt thereof with a higher share than that when the external additive is added.

(When adding titanium oxide fine particles alone)
The titanium oxide fine particles are externally added for the purpose of controlling chargeability and improving fluidity. First, by adding the titanium oxide fine particles, and then adding particles made of a long chain fatty acid or a salt thereof with a higher share than the titanium oxide fine particles, the titanium oxide fine particles can uniformly adhere to the toner particles. . When externally adding titanium oxide fine particles, if the toner base particles and negatively chargeable silica fine particles are mixed with a high share from the beginning, the titanium oxide fine particles are embedded in the toner base particles and the charging uniformity of the resulting toner is impaired. . On the other hand, it is considered that particles composed of a long chain fatty acid typified by metal soap or a salt thereof have a property of not easily adhering to toner base particles or toner base particles to which titanium oxide fine particles are added. Therefore, when externally adding fine particles comprising a long-chain fatty acid or a salt thereof, by increasing the mixing share, the long-chain fatty acid or a salt thereof is attached to the surface of the toner base particles by physical force. Alternatively, particles comprising a long chain fatty acid or a salt thereof can be melted, dissolved or softened by frictional heat, and can be efficiently and uniformly attached to the surface of the toner base particles. Due to the effect of the long chain fatty acid or its salt as a binder, the titanium oxide fine particles are uniformly deposited on the toner surface without being embedded in the toner base particles, and the separation of the titanium oxide fine particles from the toner surface is suppressed. Is done. Furthermore, the effect of the long-chain fatty acid or salt thereof as a toner lubricant is further exhibited, and the uniformity of charging is maintained. In addition, charging stability is maintained even when the toner is used repeatedly. Also, in the developing unit, contact between the toner and the photoreceptor causes the long-chain fatty acid or a salt thereof to migrate to the photoreceptor surface, lubricate the photoreceptor surface, and the photoreceptor is polished by an external additive on the toner surface. Can be prevented.

(When adding titanium oxide fine particles and negatively chargeable silica fine particles in combination)
When titanium oxide fine particles and negatively chargeable silica fine particles are used as external additives, both control the chargeability of the toner and improve the fluidity. The order of adding these two external additives is not particularly limited. That is, after adding titanium oxide fine particles first, negatively chargeable silica fine particles are added; simultaneously added; negatively chargeable silica fine particles are added first, and then titanium oxide fine particles are added. Further, since the large particle size silica and the small particle size silica are used as the negatively chargeable silica fine particles, when the negatively chargeable silica fine particles are used, the following external additives are used in the toner production method of the present invention. (I) Titanium oxide fine particles-negatively charged silica fine particles-particles made of long chain fatty acids or salts thereof; (ii) Negatively charged silica fine particles-titanium oxide fine particles-long chain fatty acids or salts thereof. (Iii) (negatively charged silica fine particles + titanium oxide fine particles) -particles consisting of long chain fatty acids or salts thereof; (iv) (large particle diameter silica + small particle diameter silica) -titanium oxide fine particles-long chain Particles made of fatty acid or salt thereof; (v) Small particle size silica— (large particle size silica + titanium oxide fine particles) —particle made of long chain fatty acid or salt thereof;

  Among these, from the viewpoint of charging stability, it is preferable to first add negatively chargeable silica fine particles. When the negatively chargeable silica fine particles are added alone, the electrostatic attractive force between the toner base particles and the negatively chargeable silica fine particles is not disturbed by other external additives. Furthermore, since the difference between the work function of the negatively chargeable silica fine particles and the work function of the toner base particles is large, the negatively chargeable silica fine particles can be strongly adhered to the toner base particles. As a result, the desorption of the negatively chargeable silica fine particles is prevented, the change in chargeability is reduced, and the effect that the chargeability is stabilized in the long term is obtained. Also, as the negatively chargeable silica fine particles, the combination of small particle size silica and large particle size silica can increase the absolute value of the charge amount, provide long-term charge stability, and toner fluidity. This is preferable from the standpoint of improving toner and exhibiting a heat blocking effect to improve the storage stability of the toner.

  It is preferable that the share at the time of adding the titanium oxide fine particles and the negatively chargeable silica fine particles be the same share in order to prevent the embedding of these fine particles and to ensure fluidity.

  Next, particles comprising a long chain fatty acid or a salt thereof are externally added. The external addition is performed with a higher share than the share (shearing force) when externally adding the titanium oxide fine particles and the negatively chargeable silica fine particles. When externally adding titanium oxide and negatively chargeable silica fine particles, mixing the toner base particles and negatively chargeable silica fine particles with a high share from the beginning, the negatively chargeable silica fine particles are embedded in the toner base particles, and the resulting toner There is a risk that the charging uniformity and fluidity of the resin may be impaired. Therefore, when externally adding particles comprising a long-chain fatty acid represented by metal soap or a salt thereof, by increasing the mixing share, the long-chain fatty acid or salt thereof adheres uniformly to the toner surface, as described above. It is possible to exert effects such as prevention of detachment of the external additive from the toner surface, effect as a lubricant, and imparting lubricity to the surface of the photoreceptor.

  When externally adding fine particles of titanium oxide fine particles, negatively chargeable silica fine particles and long chain fatty acids or salts thereof, the method of increasing the mixing share depends on the device for externally adding external additives to the toner base particles. Just decide. In general, a machine or an apparatus that is usually used by those skilled in the art, such as a high-speed fluid mixer such as a Henschel mixer or a Perpenmeier, or a mixer using a mechanochemical method, is used as an apparatus used for toner production. When using a high-speed fluid mixer such as a Henschel mixer or Perpenmeier with rotor blades, increase the rotational speed of the rotor blade or reduce the gap (gap) between the rotor blade and the mixer wall. By this, it is possible to increase the share at the time of mixing particles composed of long chain fatty acids or salts thereof. When externally adding particles comprising a long-chain fatty acid or a salt thereof, 1.02 times or more, preferably 1.2 times or more, more preferably 1.5 times that of other fine particle external additives. It is preferable to apply the above high share. If a too high share is applied, other fine particles will be affected, so 3 times or less is preferable.

  As described above, in the toner of the present invention, titanium oxide fine particles, or titanium oxide fine particles and negatively-charged silica fine particles are externally added to the toner base particles, and at the final stage, particles made of long-chain fatty acids or salts thereof It is obtained by adding with a high share. For this reason, the long chain fatty acid or salt thereof is uniformly attached by physical force, or the particles of the long chain fatty acid or salt thereof are melted, dissolved or softened by frictional heat, and are efficiently applied to the surface of the toner base particles. , Can adhere uniformly. The titanium oxide fine particles and the negatively chargeable silica fine particles are not embedded in the toner base particles due to the effect of the long chain fatty acid or salt thereof as a binder. Furthermore, the release of these external additives from the toner surface is suppressed, and the effect of the long-chain fatty acid or a salt thereof as a toner lubricant is further exhibited, such as charging uniformity and long-term charging stability. The effect of is maintained. In addition, charging stability is maintained even when the toner is used repeatedly. Further, in the developing unit, contact between the toner and the photoreceptor causes the long-chain fatty acid or a salt thereof to migrate to the photoreceptor surface, lubricate the photoreceptor surface, and the photoreceptor is polished by an external additive on the toner surface. Can be prevented.

  The toner of the present invention can be used in any type of image forming apparatus. An image forming apparatus using a one-component toner or an image forming apparatus using a two-component toner may be used. Further, it may be a contact developing type image forming apparatus or a non-contact type image forming apparatus. A one-component contact-type image forming apparatus that can use the toner of the present invention is described in detail in, for example, Patent Document 8. The image forming apparatus of the present invention includes a latent image carrier on which an electrostatic latent image typified by a photoreceptor is formed; toner is applied to the latent image carrier to develop the electrostatic latent image on the latent image carrier. A toner carrying member represented by a developing roll; and a developing unit having a toner regulating member for regulating the amount of toner carried from the toner carrying member to the latent image carrying member. The toner of the present invention is accommodated in a toner accommodating portion, conveyed from the toner accommodating portion to a developing roll (toner carrier), and supplied to the photosensitive member (latent image carrier) via the developing roll (toner carrier). And transferred to form an image. The toner regulating member adjusts the toner supply amount so that excessive supply from the developing roll (toner carrier) to the photosensitive member (latent image carrier) is not performed.

  Hereinafter, the present invention will be described based on examples.

(Preparation of toner base particles)
100 parts by mass of styrene-acrylic binder resin, 3.5 parts by mass of red pigment CI12055, and 1.0 part by mass of chromium salicylate complex were respectively added to Henschel mixer 20B (Mitsui Mine Co., Ltd.), and uniform. Mixed. This mixture was melt-kneaded using a twin-screw kneading extruder (PCM-30 manufactured by Ikekai Kasei Co., Ltd.), cooled, and then pulverized by jet air using a jet pulverizer 200AFG (Hosokawa Micron Corporation). Next, toner base particles having a volume average particle diameter of 8.5 μm were prepared using an air classifier 100ATP (Hosokawa Micron Corporation).

(External additive)
Table 1 shows external additives that are externally added to the toner base particles in this example.

(External processing)
In the embodiment of the present invention, in the external addition process, a predetermined amount of an external additive is added to 100 parts by mass of the toner base particles, and the Z0S0 type is added using a Henschel mixer FM20B (Mitsui Mining Co., Ltd.). Using a stirring blade, stirring and mixing were performed.

(Example 1)
100 parts by mass of the toner base particles prepared above were put into a Henschel mixer FM20B, and 1.0 part by mass of hydrophobic titanium oxide STT30S (manufactured by Titanium Industry) was added thereto, followed by treatment at 3000 rpm for 2 minutes. Next, 0.2 parts by mass of magnesium stearate was added to this processed product, and the process was performed at 4000 rpm for 2 minutes to obtain toner A. In addition, the space | interval (henceforth a gap) of the rotating blade of a mixer and a mixer wall at this time was 5 mm in either process. The production conditions for Toner A are shown in Table 2.

(Example 2)
Magnesium stearate treatment was performed at 3000 rpm for 2 minutes, which was the same as the external addition treatment of titanium oxide fine particles, and the gap was reduced from 5 mm to 2 mm during the external addition treatment of titanium oxide fine particles, in the same manner as in Example 1, Toner B was obtained by externally adding magnesium stearate. The production conditions of Toner B are shown in Table 2.

(Example 3)
100 parts by mass of toner base particles were put into a Henschel mixer FM20B, and 1 part by mass of hydrophobic negatively-charged silica RX200 (manufactured by Nippon Aerosil) and 1 part by mass of hydrophobic titanium oxide STT30S (manufactured by Titanium Industry) were simultaneously added thereto. A toner C was obtained in the same manner as in Example 1 except that. The production conditions of Toner C are shown in Table 2.

(Example 4)
100 parts by mass of toner base particles were put into a Henschel mixer FM20B, and 1 part by mass of hydrophobic negatively chargeable silica RX200 was added thereto, followed by treatment at 3000 rpm for 2 minutes. Next, 1 part by mass of hydrophobic negatively-charged silica RX50 (manufactured by Nippon Aerosil Co., Ltd.) and 1.0 part by mass of hydrophobic titanium oxide STT30S (manufactured by Titanium Industry) were added simultaneously to this treated product, and the treatment was performed at 3000 rpm for 2 minutes. Went. Finally, 0.2 part by mass of magnesium stearate was added, and processing at 4000 rpm for 2 minutes was performed to obtain toner D.

(Example 5)
100 parts by weight of toner base particles are put into a Henschel mixer FM20B, and 1 part by weight of hydrophobic negatively charged silica RX200 (manufactured by Nippon Aerosil), 1 part by weight of hydrophobic negatively charged silica RX50, and hydrophobic titanium oxide 1 part by mass of STT30S (manufactured by Titanium Industry) was added at the same time, and the treatment was performed at 3000 rpm for 2 minutes. To this treated product, 0.2 part by mass of magnesium stearate was charged, and a treatment at 4000 rpm for 2 minutes was performed to obtain Toner E. The production conditions of Toner E are shown in Table 2.

(Comparative Example 1)
100 parts by mass of toner base particles were put into a Henschel mixer FM20B, 1.0 part by mass of hydrophobic titanium oxide STT30S was added, and a treatment at 3000 rpm for 2 minutes was performed. To this processed product, toner F was obtained by further processing at 4000 rpm for 2 minutes without adding anything. The production conditions of Toner F are shown in Table 2.

(Comparative Example 2)
Toner G was obtained in the same manner as in Example 1 except that the processing conditions of the Henschel mixer when adding magnesium stearate were the same as the processing conditions of titanium oxide. Table 2 shows the production conditions of the toner G.

(Comparative Example 3)
To 100 parts by mass of toner base particles, 1 part by mass of hydrophobic titanium oxide STT30S and 0.2 part by mass of magnesium stearate are simultaneously added, the gap is set to 2 mm, and the process is performed at 3000 rpm for 2 minutes to obtain toner H. Obtained. The production conditions of Toner H are shown in Table 2.

(Comparative Example 4)
1 part by mass of hydrophobic titanium oxide STT30S is added to 100 parts by mass of toner base particles, and a treatment is performed at 4000 rpm for 2 minutes. 0.2 parts by mass of magnesium stearate is added to this treated product, and 3000 rpm for 2 minutes. A toner I was obtained in the same manner as in Example 1 except that the above process was performed. The production conditions of Toner I are shown in Table 2.

(Evaluation of the obtained toner)
The obtained toner was evaluated for charge amount and charge uniformity, and the generation rate of irregular toner was determined.

  The charge amount of the toner was measured as follows using an E-SPART analyzer manufactured by Hosokawa Micron Corporation. The toner prepared in Examples and Comparative Examples and a carrier (KBN100 ferrite carrier manufactured by Hitachi Metals, Ltd.) were mixed so as to have a toner concentration of 0.1% by mass, and stirred at 100 rpm for 15 minutes to charge the toner. . Thereafter, the toner and the carrier were separated by blowing nitrogen gas onto the mixture of the toner and the carrier. Next, the charge amount (Q / m) for each toner is measured, and the measured toner is measured for at least 100 toner particles having an average particle diameter of ± 0.1 μm obtained by a Coulter counter. Is plotted on the X axis, and the total charge amount represented by the following equation is plotted on the Y axis as the total charge amount.

  Here, if toner particles having the same particle diameter and charge amount are plotted, when the number of toners and the total charge amount are plotted, a straight line passing through the origin with correlation coefficient = 1 should be obtained. The number of toners and the measured value of the total charge amount were plotted, and the deviation from the straight line was evaluated by the correlation coefficient.

  At the same time, the number of positively charged toners (reversely charged toners) that are irregular toners was measured to determine the rate of occurrence of irregular toners.

  The results are shown in FIG. FIG. 1 is a diagram showing the correlation for toner A. FIG. Table 3 shows the correlation coefficient (hereinafter simply referred to as correlation coefficient) between the number of toners and the total charge obtained from the plots (not shown except toner A) shown in FIG. The occurrence rate of irregular toner.

  From the results shown in Table 3, titanium oxide fine particles were externally added first, and then, the rotational speed of the stirring blade was increased to increase the share at the time of addition to obtain particles of long chain fatty acids or salts thereof. Toner obtained in Example 1 and a toner obtained by externally adding a long-chain fatty acid or a salt thereof by reducing the gap between the mixer and the rotor blade to increase the share at the time of addition (Example 2) ) Has a correlation coefficient of 0.993 or more between the number of toners and the total charge amount, and the generation rate of irregular toner is also low. That is, it can be seen that the charge amount for each toner is stable, and the charge of the entire toner is uniform.

  In addition, the order of addition of negatively-charged silica fine particles (small particle size silica and large particle size silica) and titanium oxide was changed, and finally the number of rotations of the stirring blade when adding particles consisting of long chain fatty acids or salts thereof was increased. In the toners C to E (Examples 3 to 5) obtained by increasing the share at the time of external addition of particles comprising a long-chain fatty acid or a salt thereof, the correlation between the number of toners and the total charge amount The number is 0.99 or more, and the generation rate of irregular toner is also low. That is, it can be seen that the charge amount for each toner is stable, and the charge of the entire toner is uniform.

  On the other hand, Toner F (Comparative Example 1) processed without adding magnesium stearate after addition of titanium oxide fine particles and further increasing the number of rotations had an extremely high release rate of titanium oxide. When this toner F and the toner A obtained in Example 1 are compared, by adding magnesium stearate with a high share at the last stage, the fine particles of titanium oxide are efficiently retained, and the uniformity of charging is improved. It became clear that the generation of irregular toner was suppressed as well.

  In addition, titanium oxide fine particles and long chain fatty acids or salts thereof are sequentially added in a multistage process, but when the share at the time of addition is the same (Comparative Example 2), or titanium oxide fine particles and long chain fatty acids or salts thereof are simultaneously added. When added (that is, with the same share) (Comparative Example 3), the correlation coefficient is slightly lower than that of each toner of the example, and the generation rate of irregular toner is also increased. This suggests that it is preferable to add titanium oxide fine particles and then add a long-chain fatty acid or a salt thereof with the next highest share.

  Furthermore, Toner I (Comparative Example 4) obtained by first adding titanium oxide fine particles with a high share and then adding a long-chain fatty acid or a salt thereof with a lower share than when adding titanium oxide fine particles, It was found that the correlation coefficient was as low as 0.93 and the generation rate of irregular toner was high.

  The toner of the present invention obtained by first externally adding titanium oxide fine particles, or titanium oxide fine particles and negatively chargeable silica fine particles, and then externally adding a long-chain fatty acid or a salt thereof with an increased share, is toner 1 The charge amount of each toner is stable, the charge of the whole toner is uniform, and the charge stability is maintained even after repeated use, and the generation rate of irregular toner is low, so a stable image is provided. obtain. Therefore, the toner of the present invention is widely used as an electrophotographic toner.

It is a figure which shows the relationship between the toner number when charging the toner of this invention, and total charge amount.

Claims (14)

  A step of adding titanium oxide fine particles to toner base particles containing a binder resin and a colorant; and a step of adding particles comprising a long-chain fatty acid or a salt thereof with a share higher than the share at the time of adding the titanium oxide fine particles; Toner obtained in this order.   A step of adding titanium oxide fine particles and negatively chargeable silica fine particles as external additives to toner base particles containing a binder resin and a colorant; then, particles comprising a long-chain fatty acid or a salt thereof are added at the time of addition of the external additive A toner obtained by performing the step of adding at a higher share than the share in this order.   The toner according to claim 2, wherein the negatively chargeable silica fine particles and the titanium oxide fine particles are simultaneously added to the toner base particles.   The step of adding the titanium oxide fine particles and the negatively chargeable silica fine particles as external additives comprises first adding the negatively chargeable silica fine particles to the toner base particles, and then adding the titanium oxide fine particles. The toner described.   The addition of the titanium oxide fine particles, the negatively chargeable silica fine particles and the particles of long chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and by controlling the rotational speed of the rotor blade, the long chain fatty acid or The toner according to claim 1, wherein a share at the time of addition of particles made of the salt is increased.   The addition of the titanium oxide fine particles, the negatively charged silica fine particles, and the particles composed of the long chain fatty acid or a salt thereof is performed using a mixer having a rotary blade, and the distance between the rotary blade and the mixer wall is controlled. The toner according to any one of claims 1 to 4, wherein a share at the time of adding particles composed of a long-chain fatty acid or a salt thereof is increased.   A step of adding titanium oxide fine particles to toner base particles containing a binder resin and a colorant; and a step of adding particles comprising a long-chain fatty acid or a salt thereof with a share higher than the share at the time of adding the titanium oxide fine particles; In this order.   A step of adding titanium oxide fine particles and negatively chargeable silica fine particles as external additives to toner base particles containing a binder resin and a colorant; then, particles comprising a long-chain fatty acid or a salt thereof are added at the time of addition of the external additive A method for producing a toner, comprising the steps of adding in a higher share than the share in this order.   The method for producing a toner according to claim 8, wherein the negatively chargeable silica fine particles and the titanium oxide fine particles are simultaneously added to the toner base particles.   9. The step of adding titanium oxide fine particles and negatively chargeable silica fine particles as external additives comprises first adding negatively chargeable silica fine particles to toner base particles, and then adding titanium oxide fine particles. A method for producing the toner according to the description.   The addition of the titanium oxide fine particles, the negatively chargeable silica fine particles and the particles of long chain fatty acid or a salt thereof is performed using a mixer having a rotor blade, and by controlling the rotational speed of the rotor blade, the long chain fatty acid or The method for producing a toner according to any one of claims 7 to 10, wherein a share at the time of adding particles made of the salt is increased.   The addition of the titanium oxide fine particles, the negatively charged silica fine particles, and the particles composed of the long chain fatty acid or a salt thereof is performed using a mixer having a rotary blade, and the distance between the rotary blade and the mixer wall is controlled. The method for producing a toner according to any one of claims 7 to 10, wherein a share at the time of adding particles composed of a long-chain fatty acid or a salt thereof is increased.   An image forming apparatus comprising the toner according to claim 1.   A latent image carrier on which an electrostatic latent image is formed; a toner carrier that transports toner to the latent image carrier to develop the electrostatic latent image on the latent image carrier; and from the toner carrier The image forming apparatus according to claim 13, further comprising: a developing unit having a toner regulating member that regulates an amount of toner conveyed to the latent image carrier.

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