JP2009265471A - Electrostatic charge image developing toner and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing toner which has environmentally friendly developing property and transferring property and can stably form a high-quality image over a long period. <P>SOLUTION: The electrostatic charge image developing toner, which contains toner particles comprising at least a binder resin, carboxylic acid and a colorant, and an external additive, further contains alumina particles which are treated with silicone oil and have a number average primary particle size of 10 to 30 nm, by 0.1 to 2.0 mass%. The image forming method using the electrostatic image developing toner is also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic image developing toner and an image forming method using the same.

  In the electrophotographic system, it is necessary to perform charging, exposure, development, transfer, and fixing processes, and to superimpose several types of electrostatic image developing toners (hereinafter also simply referred to as toners) having different colors on the same support. is there. The chargeability, fluidity, and fixability of each color toner are extremely important factors.

  That is, in order to maintain stable and good color reproducibility of an image, it is necessary to first transfer a predetermined amount of toner onto the transfer paper from the development process to the transfer process. The toner adhesion amount in the development and transfer processes is greatly influenced by various charging properties such as toner charge rising property, life stability and environment dependency, fluidity, and fixing property. For this reason, an external additive is added to the toner base particles containing a binder resin, a colorant and the like in order to improve and adjust the chargeability and fluidity.

  As an external additive for improving and adjusting chargeability, fluidity and the like, generally, a toner in which fine powder of inorganic oxide, in many cases silica fine particles and alumina fine particles are added to the toner base particles is obtained (for example, Patent Document 1). However, in the case of normally used silica fine particles, the effect of improving the fluidity of the toner is particularly excellent, but the negative polarity is strong and the charge amount of the negatively chargeable toner is excessively increased particularly under low temperature and low humidity.

Further, since moisture is taken in under high temperature and high humidity to reduce the charge amount, a large difference in charge amount occurs between low temperature and low humidity and high temperature and high humidity, that is, the environment dependency becomes poor. As a result, the amount of toner transported on the developer carrier and the amount of charge cannot be optimized at both high temperature and high humidity and low temperature and low humidity, resulting in poor image density reproduction, fogging, toner dropping, Furthermore, there is a problem of causing in-flight contamination.
JP 2002-296830 A

  An object of the present invention is to provide a toner for developing an electrostatic image, which has excellent developability and transferability with respect to the environment, and can stably form a high-quality image over a long period of time.

  The above object of the present invention can be achieved by the following configuration.

  1. In an electrostatic charge image developing toner containing toner particles composed of at least a binder resin, a carboxylic acid and a colorant and an external additive, alumina particles treated with silicone oil and having a number average primary particle size of 10 to 30 nm are 0.1%. A toner for developing an electrostatic image, characterized by containing -2.0% by mass.

  2. 2. The electrostatic image developing toner according to 1 above, wherein the amount of carboxylic acid contained in the electrostatic image developing toner is 0.1 to 80 mg / g per 1 g of resin.

  3. 3. An image forming method, wherein an image is formed using the electrostatic charge image developing toner according to 1 or 2 above.

  According to the present invention, it is possible to provide a toner for developing an electrostatic charge image that has excellent developability and transferability with respect to the environment and can stably form a high-quality image over a long period of time.

  The present invention will be described in more detail.

  The inventors of the present application considered controlling the charge amount and the environment dependency by externally adding alumina particles to the toner particles. Alumina particles have an effect of promoting charge transfer, which also has an effect of improving the rising property of charge and sharpening the charge amount distribution, that is, improving the environmental dependency. However, high-quality images cannot be stably formed over a long period of time simply by adding alumina particles.

  The present invention achieves the above object by containing 0.1 to 2.0 mass% of alumina particles obtained by treating silicon particles with alumina particles having a number average primary particle size of 10 to 30 nm as an external additive of toner particles. We were able to. When the number average primary particle diameter of the alumina particles is 10 to 30 nm, the object of the present invention can be achieved with little performance change against environmental fluctuation. The number average primary particle size is more preferably 15 to 25 nm.

  If the addition amount of the alumina particles is within this range, the performance change with respect to the environmental fluctuation is small and the charge amount of the toner is also large.

  The toner particles of the present invention are characterized by comprising at least a binder resin, a carboxylic acid, and a colorant. The carboxylic acid content is preferably 0.1 to 80 mg / g per gram of toner particles. More preferably, it is 10-60 mg / g, Most preferably, it is 30-50 mg / g. When the content of carboxylic acid is within the range of the present invention, there is no decrease in the amount of electricity, the fixing temperature does not change, and no offset occurs.

  It is presumed that treating the alumina particles with silicone oil is a treatment for changing the alumina particles from hydrophilic to hydrophobic, and performing an ability-reducing treatment for reducing environmental differences.

[Silicone oil treated alumina particles]
The alumina particles according to the present invention refer to aluminum oxide represented by Al ₂ O ₃ , and α-type alumina particles and γ-type alumina particles exist, but either one may be used. The shape of the alumina particles is preferably a spherical shape that has a high fluidity-imparting effect on the toner particles.

  The number average primary particle diameter of the alumina particles is specifically measured by the following method. A 30,000 times photograph of the toner particles is taken with a scanning electron microscope, and the photograph image is captured by a scanner. The external additive present on the toner particle surface of the photographic image is binarized by an image processing analyzer LUZEX AP (manufactured by Nireco), and the horizontal ferret diameter is calculated for 100 external additives. The average value is taken as the number average primary particle size. Moreover, it was judged by visually observing the scanning electron micrograph that the shape was spherical.

  When the number average primary particle size of the external additive is small and exists as an aggregate on the toner particle surface, the particle size of the primary particles forming the aggregate is measured.

  Silicone oil-treated alumina particles according to the present invention are those obtained by treating the above-mentioned alumina particles with silicone oil.

  Examples of the silicone oil include those represented by the following formula.

  Examples include dimethylpolysiloxane and polydimethylsiloxanediol represented by the following general formula (1).

(In the formula, R ₁ and R ₂ represent CH ₃ or OH, n represents the number of repeating units, and represents an integer of 1 or more.)
Moreover, the methyl hydrogen polysiloxane etc. which are represented by following General formula (2) are mentioned.

(In the formula, n is the number of repeating units and represents an integer of 1 or more.)
Further, methylphenyl polysiloxane represented by the following general formula (3) is also included.

(In the formula, x and y are the number of repeating units and represent an integer of 1 or more.)
Examples thereof include silicone oils represented by the following general formulas (4) and (5) having an organo group having at least one nitrogen atom in the side chain.

(Wherein R ₁₁ represents hydrogen, an alkyl group, an aryl group or an alkoxy group, R ₁₂ represents an alkylene group or a phenylene group, R ₁₃ and R ₁₄ represent hydrogen, an alkyl group or an aryl group, and R ₁₅ represents Represents a nitrogen-containing heterocyclic group, wherein the alkyl group, aryl group, alkylene group, and phenylene group may have an organo group having a nitrogen atom, or a substituent such as halogen as long as the chargeability is not impaired. May be included.)
Furthermore, these silicone oils may be subjected to alkyl modification, amino modification, epoxy modification, epoxy / polyether modification, carboxyl modification, mercapto modification, alcohol modification, fluorine modification, and the like as required.

  As a silicone oil treatment method of alumina particles using these silicone oils, it is possible to treat alumina particles by adding them when they are dispersed in a wet or dry manner so as to have a primary particle size mechanically. .

  Specific examples of the dry method include a technique of adding silicone oil together with alumina particles to a mixer such as a Henschel mixer and mixing and stirring, and a technique of spraying silicone oil on alumina particles.

  Examples of the wet method include a method in which a silicone oil is dissolved or dispersed in a solvent such as hexane, mixed with alumina particles, and then removed to remove the solvent.

  The addition amount at this time is preferably 1 to 30% by mass, more preferably 5 to 20% by mass with respect to the alumina particles. This is because by setting the content to 1 to 30% by mass, the effects of imparting fluidity to the toner and stabilizing the charge amount can be enhanced.

  Next, materials constituting the toner particles will be described.

(Binder resin)
As the polymerizable monomer constituting the binder resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichloro are used. Styrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn -Styrene or styrene derivatives such as decylstyrene, pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-methacrylate Octyl, 2-ethylhexyl methacrylate, stearyl methacrylate Methacrylic acid ester derivatives such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride and vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. There are acrylic acid or methacrylic acid derivatives such as vinyl compounds, acrylonitrile, methacrylonitrile, acrylamide and the like. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the binder resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, a phosphoric acid group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumar Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxy And propyl methacrylate.

  Furthermore, multifunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris- Peroxide polymerization initiator or a peroxide such as t- butylperoxy) triazine and the like polymeric initiator having a side chain.

  Moreover, when using an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

(Chain transfer agent)
In order to adjust the molecular weight of the binder resin, a generally used chain transfer agent can be used. The chain transfer agent used is not particularly limited. For example, mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, and mercaptopropionate esters such as n-octyl-3-mercaptopropionate. , Terpinolene, carbon tetrabromide and α-methylstyrene dimer are used.

(Coloring agent)
Examples of the colorant include inorganic pigments, organic pigments, and dyes.

  A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, and the like.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As the dye, C.I. I. Solvent Red 1, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Solvent Red 58, C.I. I. Solvent Red 63, C.I. I. Solvent Red 111, C.I. I. Solvent Red 122, C.I. I. Solvent Yellow 19, C.I. I. Solvent Yellow 44, C.I. I. Solvent Yellow 77, C.I. I. Solvent Yellow 79, C.I. I. Solvent Yellow 81, C.I. I. Solvent Yellow 82, C.I. I. Solvent Yellow 93, C.I. I. Solvent Yellow 98, C.I. I. Solvent Yellow 103, C.I. I. Solvent Yellow 104, C.I. I. Solvent Yellow 112, C.I. I. Solvent Yellow 162, C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 60, C.I. I. Solvent Blue 70, C.I. I. Solvent Blue 93, C.I. I. Solvent blue 95 etc. can be used and these mixtures can also be used.

  These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

(Release agent)
A known compound can be used as the release agent used in the present invention.

  As such, for example, polyolefin wax such as polyethylene wax and polypropylene wax, long chain hydrocarbon wax such as paraffin wax and sazol wax, dialkyl ketone wax such as distearyl ketone, carnauba wax, montan wax, Trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitic acid, distearyl maleate, etc. And amide waxes such as ethylenediamine behenyl amide and trimellitic acid tristearyl amide.

  The amount of the release agent contained in the toner is preferably 1 to 20% by mass and more preferably 3 to 15% by mass with respect to the whole toner.

(Charge control agent)
A charge control agent can be added to the toner according to the present invention as necessary. A known compound can be used as the charge control agent.

(External additive)
The external additive added in addition to the alumina particles described above will be described.

  As the inorganic fine particles, various inorganic oxides, nitrides, borides and the like are preferably used. For example, silica, zirconia, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, cerium oxide, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide, oxide Examples thereof include boron, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride. Further, the inorganic fine particles may be subjected to a hydrophobic treatment.

  As the organic fine particles, spherical organic fine particles having a number average primary particle size of about 10 to 2000 nm can be used. Specifically, styrene resin fine particles, styrene acrylic resin fine particles, polyester resin fine particles, urethane resin fine particles and the like are preferably used.

[Toner Preparation Method]
Next, a toner manufacturing method will be described.

  The method for producing the toner is not particularly limited, but a method using an emulsion association method is preferably used. Particularly preferred is a production method in which resin particles having a multi-stage polymerization structure formed by emulsion polymerization of miniemulsion polymerized particles are associated (aggregated / fused).

Hereinafter, an example of a method for producing a toner by the miniemulsion polymerization association method will be described in detail. In this toner manufacturing method, the toner is manufactured through the following steps.
(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer (2) The polymerizable monomer solution in which the release agent is dissolved / dispersed is formed into droplets in a solution medium, and the mini Polymerization step for preparing a dispersion of resin particles by emulsion polymerization (3) Colorant dispersion step for dispersing a colorant in the contained solution medium (4) Associating the resin particles with the colorant particles in the solution medium Aggregation / fusion step for obtaining particles (5) Aging step for adjusting the shape by aging the associated particles with heat energy to form toner particles (6) Cooling step for cooling the dispersion of toner particles (7) Cooling The toner particles are solid-liquid separated from the toner particle dispersion, and the surfactant is removed from the toner base. (8) The washed toner particles are dried. (9) The toner particles are dried. Add external additives to toner particles That process steps will be described below.

(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to a solution medium containing a surfactant, and mechanical energy is increased. In addition, droplets are formed, and then the polymerization reaction proceeds in the droplets by radicals from the water-soluble radical polymerization initiator. Note that resin particles may be added as core particles to the solution medium.

  By this polymerization step, resin particles containing a release agent and a binder resin are obtained. The resin particles to be applied may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using uncolored resin particles, in the aggregation step described later, the dispersion of the colorant particles is added to the dispersion of the resin particles to aggregate the resin particles and the colorant particles. It can be a particle.

(3) Dispersing Step of Colorant Particles This step is a step of adding colorant particles to a solution medium containing a surfactant and dispersing the colorant particles in the solution medium using a dispersing device.

  The dispersing device used in the step of dispersing the colorant particles is not particularly limited, and a known device can be used. Preferred dispersing devices include pressure dispersers such as an ultrasonic disperser, a mechanical homogenizer, a manton gourin, and a pressure homogenizer, and medium dispersers such as a sand grinder, a Getzman mill, and a diamond fine mill.

  The colorant may be surface-modified. In the surface modification method of the colorant, the colorant particles are dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant particles are filtered off, washed and filtered with the same solvent, and then dried to obtain a colorant treated with the surface modifier.

(4) Aggregation / fusion process The aggregation process is a process of forming colored particles using the resin particles and the colorant particles obtained by the polymerization process. In the aggregation step, resin particles and colorant particles can be aggregated together with release agent particles, internal additive particles such as charge control agents, and the like.

  A preferred aggregating method is to add a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like as an aggregating agent having a critical aggregation concentration or more in water in which resin particles and colorant particles are present, In this method, the particles are aggregated by heating to a temperature not lower than the glass transition temperature of the resin particles and not lower than the melting peak temperature (° C.) of the release agent.

(5) Aging process Aging is preferably performed by thermal energy (heating).

  Specifically, the liquid containing the associated particles is heated and stirred to adjust the shape of the associated particles to the desired circularity by adjusting the heating temperature, stirring speed, and heating time to obtain toner particles. .

(6) Cooling step This step is a step of cooling (rapid cooling) the dispersion of toner particles. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(7) Washing Step In this solid-liquid separation / washing step, the solid-liquid separation process for solid-liquid separation of the toner particles from the dispersion liquid of the toner particles cooled to a predetermined temperature in the above step, and the solid-liquid separated toner A cleaning process is performed to remove deposits such as surfactants and salting-out agents and the alkali agent used in the aging step from the cake (aggregation obtained by agglomerating toner particles in a wet state).

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate reaches 10 μS / cm. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(8) Drying Step This step is a step of drying the washed toner cake to obtain dried toner particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(9) Step of Mixing External Additives with Toner Particles This step is a step of preparing an electrostatic image developing toner by mixing two or more external additives according to the present invention with toner particles. As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

  As conditions for the mixing apparatus, the peripheral speed is preferably 20 to 50 m / sec. The treatment time is preferably 3 to 40 minutes, but the treatment time is preferably set longer because the smaller the external additive, the easier it is for the external additive particles to aggregate.

[Developer / Photoreceptor]
The toner for developing an electrostatic image of the present invention can be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer, or a magnetic one-component developer containing about 0.1 μm to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle diameter of the carrier is preferably 20 to 100 μm, more preferably 20 to 70 μm in terms of mass average particle diameter.

  The particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The coating resin is not particularly limited, and for example, an olefin resin, a styrene resin, a styrene-acrylic resin, a silicone resin, an ester resin, a fluorine-containing polymer resin, or the like is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene-acrylic resin, polyester resin, fluorine resin, phenol resin, etc. are used. be able to. Among these, a coat carrier coated with a styrene-acrylic resin is more preferable because it can prevent the external additive from being detached and ensure durability.

  The photoreceptor used in the present invention is obtained by forming a coating film containing a photosensitive layer on a substrate. As these photoreceptors, those conventionally used widely can be used.

[Image Forming Method and Image Forming Apparatus Used in the Present Invention]
Next, an image forming method and an image forming apparatus for forming a toner image using the toner of the present invention will be described.

  FIG. 1 is a schematic view showing an example of an image forming apparatus in which the toner of the present invention can be used.

  In FIG. 1, 1Y, 1M, 1C and 1K are photosensitive members, 4Y, 4M, 4C and 4K are developing means, 5Y, 5M, 5C and 5K are primary transfer rolls as primary transfer means, and 5A is a secondary transfer. Secondary transfer rolls as means, 6Y, 6M, 6C and 6K are cleaning means, 7 is an intermediate transfer member unit, 24 is a heat roll type fixing device, and 70 is an intermediate transfer member.

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7 as a transfer unit, and a recording member P. An endless belt-shaped sheet feeding / conveying means 21 and a heat roll type fixing device 24 as a fixing means. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first photoconductor, and a periphery of the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roll 5Y as a primary transfer unit, and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first photoconductor, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roll 5M as a primary transfer unit, and a cleaning unit 6M. In addition, an image forming unit 10C that forms a cyan image as another different color toner image is disposed around the photoconductor 1C as a drum-type photoconductor 1C as a first photoconductor. The charging unit 2C, the exposure unit 3C, the developing unit 4C, the primary transfer roll 5C as the primary transfer unit, and the cleaning unit 6C are provided. Further, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photosensitive member 1K as a first photosensitive member, and the photosensitive member 1K. It has a charging means 2K, an exposure means 3K, a developing means 4K, a primary transfer roll 5K as a primary transfer means, and a cleaning means 6K.

  The endless belt-like intermediate transfer body unit 7 has an endless belt-like intermediate transfer body 70 as an intermediate transfer endless belt-like second image carrier that is wound around a plurality of rolls and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rolls 5Y, 5M, 5C, and 5K, and is combined. A colored image is formed. A recording member P such as a sheet as a transfer material accommodated in the sheet feeding cassette 20 is fed by the sheet feeding / conveying means 21, passes through a plurality of intermediate rolls 22 A, 22 B, 22 C, 22 D, and a registration roll 23, and is secondary A color image is transferred onto the recording member P at a time by being conveyed to a secondary transfer roll 5A as a transfer means. The recording member P to which the color image has been transferred is fixed by the heat roll type fixing device 24, is sandwiched by the paper discharge roll 25, and is placed on the paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording member P by the secondary transfer roll 5A, the residual toner is removed from the endless belt-shaped intermediate transfer body 70 from which the recording member P is separated by the curvature by the cleaning means 6A.

  During the image forming process, the primary transfer roll 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rolls 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roll 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the recording member P passes through the secondary transfer roll 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10K, and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rolls 71, 72, 73, 74, and 76, primary transfer rolls 5Y, 5M, 5C, and 5K, and a cleaning unit. 6A.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this way, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and are collectively applied to the recording member P. The image is transferred, and fixed by pressing and heating with a heat roll type fixing device 24 and fixed. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P are cleaned with the cleaning device 6A to remove the toner remaining on the photoreceptor, and then the above-described charging, exposure, and development cycle. The next image formation is performed.

[Transfer material]
The transfer material used in the present invention is a support for holding a toner image, and is usually called an image support, a recording material, or transfer paper. Specifically, various transfer materials such as plain paper and fine paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, cloth, etc. However, it is not limited to these.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

Example 1
(Production of silicone oil-treated alumina particles A)
As a silicone oil, 10 parts by mass of dimethylpolysiloxane represented by the general formula (1) is charged into a Henschel mixer for 100 parts by mass of alumina particles having a primary particle diameter of 20 nm, and the peripheral speed of the stirring blade is 20 m / s for 10 minutes. Treatment was performed to obtain silicon oil-treated alumina particles A.

(Production of silicone oil-treated alumina particles B)
In the same manner as that for the silicone oil-treated alumina particles A, the silicone oil-treated alumina particles B were obtained by changing the silicone oil to methylhydropolysiloxane represented by the general formula (2).

(Manufacture of silicone oil-treated alumina particles C to F)
In the same manner as the silicone oil-treated alumina particles A, the silicone oil and alumina particles C to F were obtained by changing the particle sizes of the silicone oil and alumina particles as shown in Table 1.

(Manufacture of silicone oil-treated silica particles)
In the same manner as for the silicone oil-treated alumina particles A, silica particles having a particle diameter of 20 nm were used instead of the alumina particles to obtain silicone oil-treated silica particles.

(Manufacture of colorant fine particles)
Anionic surfactant 59.0 g was dissolved in 1600 ml of ion-exchanged water with stirring. While stirring this solution, C.I. I. 200 g of CI Pigment Blue 15: 3 was added, and then a dispersion liquid of colorant fine particles was prepared by performing a dispersion treatment using a dispersion apparatus “SC Mill” (manufactured by Mitsui Mining Co., Ltd.). The volume average particle diameter of the colorant fine particles in this colorant dispersion was measured using a dynamic light scattering particle size analyzer “Microtrack UPA150” (manufactured by Nikkiso Co., Ltd.), and found to be 150 nm.

(Manufacture of multistage resin particles)
<First stage polymerization>
Into a 5 liter reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, 8 g of sodium dodecyl sulfate was charged with 3 liters of ion-exchanged water, and the internal temperature was 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to. After raising the temperature, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the solution temperature was again 80 ° C., and after dropwise addition over the following monomer mixture over 1 hour, the mixture was heated at 80 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin particles. This is referred to as “resin particles (1H)”.
Styrene 480g
n-Butyl acrylate 250g
Methacrylic acid 68.0g
n-octyl mercaptan 16.0 g
<Second stage polymerization>
A 5 liter reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution prepared by dissolving 7 g of polyoxyethylene (2) sodium dodecyl ether sulfate in 800 ml of ion-exchanged water and heated to 98 ° C. Then, 260 g of the resin particles (1H) and a solution obtained by dissolving the following monomer solution at 90 ° C. were added, and a mechanical disperser CLEARMIX (manufactured by M Technique Co., Ltd.) having a circulation path was used. Mixing and dispersing for a time, a dispersion containing emulsified particles (oil droplets) was prepared.
Styrene 245g
120g of n-butyl acrylate
n-Octyl mercaptan 1.5g
190 g of ester wax (melting point 70 ° C.)
Next, an initiator solution in which 6 g of potassium persulfate is dissolved in 200 ml of ion exchange water is added to this dispersion, and the system is heated and stirred at 82 ° C. for 1 hour to obtain resin particles. It was. This is referred to as “resin particles (1HM)”.

<Third stage polymerization>
Furthermore, a solution in which 11 g of potassium persulfate was dissolved in 400 ml of ion-exchanged water was added, and under a temperature condition of 82 ° C.,
Styrene 435g
n-Butyl acrylate 130g
Methacrylic acid 33g
n-Octyl mercaptan 8g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin particles. This is designated as “resin A- (1)”.

(Manufacture of single layer resin B)
Into a 5 liter reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, 2.3 g of sodium dodecyl sulfate and 3 liters of ion-exchanged water were added, and the internal temperature was maintained while stirring at a stirring speed of 230 rpm in a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, the liquid temperature was again 80 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 80 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin particles. This is designated as “resin B- (1)”.
Styrene 520g
210g of n-butyl acrylate
Methacrylic acid 68.0g
n-octyl mercaptan 4.0 g
(Aggregation / fusion process)
In a 5-liter reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 300 g of resin A- (1) in terms of solid content, 1400 g of ion-exchanged water, and 120 g of “colorant dispersion 1” A solution prepared by dissolving 3 g of sodium polyoxyethylene (2) sodium dodecyl ether sulfate in 120 ml of ion-exchanged water was prepared, the temperature of the solution was adjusted to 30 ° C., and a 5 mol / l sodium hydroxide aqueous solution was added to adjust the pH to 10 Adjusted. Next, an aqueous solution in which 35 g of magnesium chloride was dissolved in 35 ml of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised and the system was heated to 90 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 90 ° C. In this state, the particle size of the associated particles was measured with “Coulter Multisizer III”, and when the volume-based median diameter reached 3.1 μm, 45 g of resin B- (1) was added in terms of solid content. Further, the particle growth reaction was continued. When the desired particle size is reached, an aqueous solution in which 150 g of sodium chloride is dissolved in 600 ml of ion-exchanged water is added to stop particle growth, and further, by heating and stirring at a liquid temperature of 90 ° C. as a fusing step, Fusion between the particles was allowed to proceed until the circularity was 0.965 as measured by FPIA-2100. Thereafter, the solution was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.0, and stirring was stopped.

(Washing / drying process)
Solid-liquid separation was performed with a particle separator “MARK III Model No. 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) produced in the aggregation / fusion process to form a wet cake of toner base particles. The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles were prepared by drying until the amount became 0.5% by mass.

(Preparation of Toner 1)
To the toner base particles obtained above, 1.2% by mass of hydrophobic silica (number average primary particle size = 12 nm) and 1.0 part by mass of silicone oil-treated alumina particles A are added and mixed with a Henschel mixer. A toner 1 of the present invention was produced.

(Production of toners 2 to 14)
In the production of the toner base particles obtained above, the amount of carboxylic acid and the silicone oil-treated alumina particles were added in the amount shown in Table 1 and mixed by a Henschel mixer to prepare toners 2 to 14 of the present invention. .

  The amount of carboxylic acid in the toner was adjusted by the amount of methacrylic acid (MMA) in Resin A and Resin B in the production of multistage resin fine particles.

(Development of developer)
Each of the above toners was mixed with a silicon carrier-coated ferrite carrier having a volume average particle diameter of 60 μm to prepare “Developers 1 to 14” having a toner concentration of 6%.

[Performance evaluation]
As an image evaluation apparatus, a digital color multifunction peripheral “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies) was used.

  For printing, each toner and each developer prepared above are loaded in order, 150,000 sheets at 20 ° C./50% RH, and 50,000 sheets at 30 ° C./85% RH, a total of 200,000 prints. In the initial state, after printing 150,000 sheets and 200,000 sheets, the following evaluation was performed.

(Charge amount)
The charge amount was measured using a blow-off charge amount measuring device “TB-200” (manufactured by Toshiba Chemical Corporation).

  The two-component developer to be measured was set in the charge amount measuring device equipped with a 400 mesh stainless steel screen, and blown with nitrogen gas for 10 seconds under the condition of a blow pressure of 50 kPa, and the charge was measured. The charge amount (−μC / g) was calculated by dividing the measured charge by the flying toner mass.

(Fixability evaluation)
In the initial state, the fixability is determined by changing the surface temperature of the heating roller of the image evaluation apparatus (measured at the center of the roller) in the range of 110 to 150 ° C. in increments of 5 ° C. at the start of printing. In addition, an A4 image having a solid black belt-like image having a width of 5 mm and a halftone image having a width of 20 mm in the vertical direction with respect to the conveyance direction is conveyed by lateral feeding, and a temperature region in which image contamination due to a fixing offset does not occur (non-offset). Region).

Evaluation criteria A: The lower limit temperature of the non-offset region is less than 130 ° C., and the temperature region is 20 ° C. or more. ○: The lower limit temperature of the non-offset region is less than 150 ° C., and the temperature region is less than 20 ° C. x: Non-offset The lower limit temperature of the region is 150 ° C. or higher.

  From Table 1, by treating silicon with silicon oil, the alumina changed from hydrophilic to hydrophobic, and environmental differences could be reduced.

  When the amount of carboxylic acid in the toner particles is 0.1 mg / g or less, the toner charge amount decreases. It can be seen that if it is 80 mg / g or more, the fixing temperature rises and offset occurs.

  On the other hand, if the amount of alumina particles added is less than 0.3% by mass, the environmental fluctuation is large and the effect is not exhibited. It can be seen that when the amount is 2% by mass or more, the charge amount of the toner decreases.

  Only the silica particles have a high resistance value, so that the chargeability due to the environment increases.

FIG. 3 is a schematic diagram illustrating an example of an image forming apparatus in which the toner of the present invention can be used.

Explanation of symbols

1Y, 1M, 1C, 1K Photoconductors 4Y, 4M, 4C, 4K Developing means 5Y, 5M, 5C, 5K Primary transfer roller as primary transfer means 5A Secondary transfer roller as secondary transfer means 6Y, 6M, 6C, 6K Cleaning means 7 Endless belt-shaped intermediate transfer body unit

Claims (3)

In an electrostatic charge image developing toner containing toner particles composed of at least a binder resin, a carboxylic acid and a colorant and an external additive, alumina particles treated with silicone oil and having a number average primary particle size of 10 to 30 nm are 0.1%. A toner for developing an electrostatic image, characterized by containing -2.0% by mass. 2. The electrostatic image developing toner according to claim 1, wherein the amount of carboxylic acid contained in the electrostatic image developing toner is 0.1 to 80 mg / g per 1 g of resin. An image forming method comprising forming an image using the electrostatic image developing toner according to claim 1.

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