JP2019200345A - Toner for developing electrical static charge image and two-component developer for developing electrical static charge image - Google Patents

Abstract

To provide a two-component developer for developing an electrical static charge image which can maintain a high image quality and can prevent attachment of recording mediums to each other even when images with a high printing rate are printed in a row.SOLUTION: The toner for developing an electrical static charge image includes toner particles including toner base particles and an external additive in the surface of the toner base particles. The toner base particles include a crystalline resin as a binder resin. The external additive includes alumina particles. The ratio of presence of the aluminum atoms in the surface of the toner particles is in the range of 0.8 atom% to 5.0 atom%, both inclusive.SELECTED DRAWING: None

Description

  The present invention relates to an electrostatic charge image developing toner and a two-component developer for developing an electrostatic charge image containing the electrostatic charge image developing toner.

  Toners used for printing are required to have higher performance as copiers and printers become popular. In recent years, a digital printing technique called print-on-demand (POD), which does not have a plate making process and performs direct printing, has attracted attention. POD is superior to conventional offset printing because it can handle both small lot printing and variable printing in which the printing contents are changed for each sheet.

  When applying a conventional electrophotographic image forming method to POD, in addition to increasing printing speed and reducing running cost, it can output at various printing rates, and stable and high-definition images can be obtained even in various environments. It is important to be able to output. In particular, in the field of graphic art with a high printing rate, when images with a high printing rate are output continuously, the external additive tends to transfer from the toner to the carrier, and the charging ability of the carrier is reduced. Cause a decrease in the amount of charge. As a result, when an electrophotographic image forming method is applied to POD, fogging on the background and toner dust at the time of transfer occur, and it is assumed that stable and high-definition image output is difficult. The

  In order to solve this problem, by using multiple types of external additives with particle size difference, shape difference and work function difference, the liberation of external additives from the toner base particles is prevented and the chargeability is stabilized. The technique to make is disclosed (for example, refer patent document 1). Patent Document 1 describes a toner including toner particles having toner base particles and an external additive. The external additive includes hydrophobic negatively chargeable silica having different average primary particle sizes and hydrophobic rutile-anatase type titanium oxide (titania particles).

  In the toner described in Patent Document 1, release of titania particles is suppressed by negatively-charged silica having a large particle diameter. However, since titania particles have low resistance, carrier particles are transferred when a small amount of charge is transferred to carrier particles. The charge transfer to the toner is promoted and the charge amount of the toner decreases. It is also conceivable that the titania particles are surface-modified with a large amount of a surface modifier in order to have the same resistance as the carrier particles.

  Further, from the viewpoint of energy saving, studies have been made on low-temperature fixing that lowers the melting temperature and melt viscosity of the binder resin contained in the toner particles to reduce the energy required for fixing the toner image onto the paper. As the temperature of the binder resin in general toner particles increases, the electrical resistance decreases and the stored charge is easily released. However, the image fixed on the paper at a low temperature does not easily reduce the electric resistance of the binder resin in the toner particles, so that the electric charge is not sufficiently discharged, and the image fixed on the paper is charged, so that the sheets are stuck together. It may be attached. Adhesion between sheets is remarkable in a printed matter with a high printing rate.

  In order to solve this problem, a technique is known that discharges a charged electric charge on an image fixed on a sheet (see, for example, Patent Document 2). Patent Document 2 describes an image forming apparatus having a humidifying device. In the technique described in Patent Document 2, a charge is applied to an image by applying a humidifying liquid to an image fixed on a sheet by a humidifier.

  In addition, a technique has been proposed in which, by applying a voltage having a polarity opposite to the surface potential of the paper according to the toner image printing rate, the surface potential of the paper after fixing is canceled and the sticking between the papers is improved. (For example, refer to Patent Document 3).

JP 2006-039023 A JP 2007-286151 A JP, 2006-122156, A

  In the technique described in Patent Document 1, titania particles are aggregated and easily separated from toner base particles, and the surface of carrier particles may be contaminated. When the surface of the carrier particles is contaminated by the external additive, the toner flow characteristics become unstable, which affects the toner transport characteristics and causes image quality fluctuations. In the technique described in Patent Document 2, the charge charged in the image cannot be sufficiently removed. Further, with the technique described in Patent Document 3, it is difficult to obtain a stable charge removal effect when image patterns having different printing rates coexist on the same surface. As described above, there is room for study for achieving both high image quality of formed images and suppression of sticking between sheets (recording media).

  An object of the present invention is to provide an electrostatic charge developing toner capable of maintaining high image quality and suppressing sticking between recording media even when images having a high printing rate are continuously printed, and the electrostatic charge development It is an object to provide a two-component developer for developing an electrostatic charge image containing a toner for use.

  The present invention provides, as one means for solving the above-described problems, an electrostatic charge image developing toner having toner particles including toner base particles and an external additive disposed on the surface of the toner base particles. The toner base particles include a crystalline resin as a binder resin, the external additive includes alumina particles, and the abundance ratio of aluminum atoms on the surface of the toner particles is 0.8 atom% or more and 5.0 atom%. An electrostatic charge image developing toner is provided as follows.

  The present invention includes, as one means for solving the above-described problems, an electrostatic charge image developing toner and carrier particles, and the carrier particles are disposed on the surface of the core material particles and the core material particles. The exposed area ratio of the core particles is 4.0% or more and 15.0% or less, and the electrostatic image developing toner is the above-described electrostatic image developing toner. A two-component developer for developing an electrostatic image is provided.

  According to the present invention, even when an image with a high printing rate is continuously printed, the electrostatic charge developing toner capable of maintaining high image quality and suppressing sticking between recording media, and the electrostatic charge developing A two-component developer for developing an electrostatic image containing the toner for use can be provided.

[Configuration of toner for developing electrostatic image]
An electrostatic charge image developing toner (hereinafter also simply referred to as “toner”) has toner base particles and toner particles including an external additive.

  The toner base particles include a crystalline resin as a binder resin.

(Crystalline resin)
The crystalline resin is a resin having crystallinity. “Crystallinity” means having a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). The “clear endothermic peak” specifically means a peak whose half-value width of the endothermic peak is within 15 ° C. when measured at a heating rate of 10 ° C./min in DSC.

  A crystalline resin will not be specifically limited if it has the said characteristic. As the crystalline resin, a known crystalline resin in this technical field can be used. Examples of the crystalline resin include a crystalline polyester resin, a crystalline polyurethane resin, a crystalline polyurea resin, a crystalline polyamide resin, and a crystalline polyether resin. A crystalline resin may be used individually by 1 type, and may use 2 or more types together.

  The crystalline resin is preferably a crystalline polyester resin from the viewpoint of improving the low-temperature fixability of the toner image on the recording medium. “Crystalline polyester resin” means a known polyester obtained by a polycondensation reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid) and its derivative with a divalent or higher alcohol (polyhydric alcohol) and its derivative. Among the resins, it means a resin having the above endothermic characteristics. The melting point of the crystalline polyester resin is not particularly limited. The melting point of the crystalline polyester resin is preferably 55 to 90 ° C, more preferably 60 to 85 ° C. When the melting point of the crystalline polyester resin is in the above range, a sufficient amount of electric charge is released in the process of melting the toner during fixing on the recording medium. The melting point of the crystalline polyester resin can be controlled by the resin composition.

  The melting point of the crystalline resin can be measured, for example, by the following method. The melting point of the crystalline resin was determined by using a differential scanning calorimeter (Diamond DSC; manufactured by Perkin Elmer), enclosing 3.0 mg of sample in an aluminum pan and setting it in a holder, and using an empty aluminum pan as a reference. A first temperature raising process in which the temperature is raised from 0 ° C. to 200 ° C. at a raising / lowering speed of 10 ° C./min, a cooling process for cooling from 200 ° C. to 0 ° C. at a cooling speed of 10 ° C./min, and a raising / lowering speed of 10 ° C./min. A DSC curve is obtained according to measurement conditions (temperature increase / cooling conditions) in which the second temperature increase process of increasing the temperature from 0 ° C. to 200 ° C. in this order is performed in this order. And based on this DSC curve, let the maximum temperature of the endothermic peak derived from the crystalline resin in a 1st temperature rising process be melting | fusing point.

  The valences of the polyvalent carboxylic acid and polyhydric alcohol constituting the crystalline polyester resin are each preferably 2 or 3, and more preferably 2 respectively. Here, a dicarboxylic acid component having a valence of 2 and a diol component having a valence of 2 will be described.

  The dicarboxylic acid component having a valence of 2 is preferably an aliphatic dicarboxylic acid, and an aromatic dicarboxylic acid may be used in combination as necessary. The aliphatic dicarboxylic acid is preferably a straight-chain type from the viewpoint of improving crystallinity. A dicarboxylic acid component may be used individually by 1 type, and may use 2 or more types together.

  Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid Acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecane Dicarboxylic acid, 1,18-octadecanedicarboxylic acid is included.

  The dicarboxylic acid component is preferably an aliphatic dicarboxylic acid having 6 to 14 carbon atoms, and more preferably an aliphatic dicarboxylic acid having 8 to 14 carbon atoms.

  Examples of aromatic dicarboxylic acids that can be used in combination with aliphatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid Is included. Aromatic dicarboxylic acids that can be used in combination with aliphatic dicarboxylic acids are preferably terephthalic acid, isophthalic acid, and t-butylisophthalic acid from the viewpoint of easy availability and easy emulsification.

  In addition, as the polyvalent carboxylic acid, a polyvalent carboxylic acid having a valence of 3 or more, such as trimellitic acid or pyromellitic acid, and an anhydride of the carboxylic acid compound or an alkyl ester having 1 to 3 carbon atoms are used. Also good.

  When the dicarboxylic acid component for forming the crystalline polyester resin is 100 mol%, the content of the aliphatic dicarboxylic acid is preferably 50 mol% or more, more preferably 70 mol% or more, and more preferably 80 mol% or more. More preferably, 100 mol% is particularly preferable. When the content is 50 mol% or more, the crystallinity of the crystalline polyester resin can be sufficiently secured.

  The diol component having a valence of 2 is preferably an aliphatic diol, and if necessary, a diol other than the aliphatic diol may be used in combination. The aliphatic diol is preferably a straight chain type from the viewpoint of improving crystallinity. A diol component may be used individually by 1 type and may use 2 or more types together.

  Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14- Tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol neopentyl glycol are included.

  The diol component is preferably an aliphatic diol having 2 to 12 carbon atoms, and more preferably an aliphatic diol having 3 to 10 carbon atoms.

  The diol that can be used in combination with the aliphatic diol includes a diol having a double bond. Examples of the diol having a double bond include 1,4-butenediol, 2-butene-1,4-diol, 3-butene-1,6-diol, and 4-butene-1,8-diol. .

  When the diol component for forming the crystalline polyester resin is 100 mol%, the aliphatic diol content is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more. Further, 100 mol% is particularly preferable. When the content of the aliphatic diol in the diol component is 50 mol% or more, the crystallinity of the crystalline polyester resin can be ensured.

  Examples of the polyhydric alcohol include glycerin having a valence of 3 or more, pentaerythritol, trimethylolpropane, and sorbitol.

  The weight average molecular weight (Mw) of the crystalline polyester resin is preferably from 3,000 to 100,000, and preferably from 4,000 to 50,000, from the viewpoint of ensuring both sufficient low-temperature fixability and long-term heat-resistant storage stability. Is more preferable, and 5,000 to 20,000 is particularly preferable. The ratio of the diol component to the dicarboxylic acid component is such that the ratio [OH] / [COOH] of the hydroxyl group equivalent [OH] of the diol component to the carboxyl group equivalent [COOH] of the dicarboxylic acid component is 1. 5/1 to 1 / 1.5 is preferable, and 1.2 / 1 to 1 / 1.2 is more preferable.

  The method for synthesizing the crystalline polyester resin is not particularly limited, and can be synthesized by polycondensation (esterification) of a polyvalent carboxylic acid and a polyhydric alcohol using a known esterification catalyst.

  Examples of catalysts that can be used in the synthesis of the crystalline polyester resin include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin , Zirconium, germanium and other metal compounds; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Examples of the tin compound include dibutyltin oxide, tin octylate, tin dioctylate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetranormal butyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrastearyl titanate; titanium acylates such as polyhydroxy titanium stearate; titanium tetraacetylacetonate, titanium lactate, titanium tritate. Titanium chelates such as ethanolamate are included. Examples of germanium compounds include germanium dioxide. Examples of the aluminum compound include oxides such as polyaluminum hydroxide, aluminum alkoxide, and tributylaluminate. These compounds may be used alone or in combination of two or more.

  The content of the crystalline resin is preferably 5.0% by mass or more and 15.0% by mass or less with respect to the total amount of the binder resin contained in the toner base particles. When the content of the crystalline resin is within the above range, the discharge effect is excellent, and the crystalline resin is not exposed on the surface of the toner base particles, and the charge amount is excellent.

  The binder resin may include an amorphous resin in addition to the crystalline resin.

(Amorphous resin)
An amorphous resin has substantially no crystallinity, and includes, for example, an amorphous part in the resin. Examples of the amorphous resin include vinyl resins, urethane resins, urea resins, amorphous polyester resins, and partially modified polyester resins. The amorphous resin preferably contains a vinyl resin. The amorphous resin can be synthesized, for example, by a known method. One type of amorphous resin may be used alone, or two or more types may be used in combination.

  The vinyl resin is a resin synthesized by polymerization of a monomer containing a compound having a vinyl group or a derivative thereof. One type of vinyl resin may be used alone, or two or more types may be used in combination.

  Examples of vinyl resins include styrene- (meth) acrylic resins. The styrene- (meth) acrylic resin has a molecular structure of a radical polymer of a compound having a radical polymerizable unsaturated bond. The styrene- (meth) acrylic resin can be synthesized, for example, by radical polymerization of a compound having a radical polymerizable unsaturated bond. As the compound having a radical polymerizable unsaturated bond, one kind may be used alone, or two or more kinds may be used in combination. Examples of the compound having a radical polymerizable unsaturated bond include styrene and derivatives thereof, and (meth) acrylic acid and derivatives thereof.

  Examples of styrene and its derivatives include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn- Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl Styrene and 3,4-dichlorostyrene are included.

  Examples of (meth) acrylic acid and its derivatives include methyl acrylate, ethyl acrylate, butyl acrylate, acrylate-2-ethylhexyl, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

  The content of the vinyl resin in the amorphous resin is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more.

  The content of the amorphous resin is preferably 50% by mass or more and 80% by mass or less with respect to the total amount of the binder resin contained in the toner base particles. If the content of the amorphous resin is within the above range, the binder resin has a high hardness, so that the resistance to crushing by mixing with carrier particles is improved.

  The crystalline resin may be a hybrid crystalline polyester resin. The hybrid crystalline polyester resin has a structure in which a crystalline polyester resin unit and an amorphous resin unit are chemically bonded.

  The “crystalline polyester resin unit” refers to a portion derived from the crystalline polyester resin in the hybrid crystalline polyester resin. “Amorphous resin unit” refers to a portion derived from a resin (amorphous resin) having no crystallinity in the hybrid crystalline polyester resin.

  As the crystalline polyester resin, the above-described crystalline polyester resin can be used. As the amorphous resin, the above-mentioned amorphous resin can be used.

  In the hybrid crystalline polyester resin, the crystalline polyester resin unit and the amorphous resin unit are crystalline polyester resin units, amorphous resin units, or a range in which these resins are chemically bonded. Any of them may be continuous or randomly arranged. Moreover, both units may be connected in a chain form, or the other may be grafted to one chain.

  The chemical bond is, for example, an ester bond or a covalent bond by an addition reaction of an unsaturated group. The hybrid crystalline polyester resin can be obtained by a known method in which a crystalline polyester resin unit and an amorphous resin unit are bonded by chemical bonding. For example, the hybrid crystalline polyester resin is obtained by polymerizing the monomer for constituting the resin unit in the main chain and the both reactive monomers and the presence of the obtained main chain precursor, so that the resin unit in the side chain And a step of polymerizing or reacting one or both of the monomer and the crystal nucleating agent for constituting the compound.

  Furthermore, substituents such as sulfonic acid groups, carboxyl groups, and urethane groups can be further introduced into the hybrid crystalline polyester resin. The introduction site of the substituent may be a crystalline polyester resin unit or an amorphous resin unit.

  The structure and amount of the main chain and side chain in the obtained resin are, for example, known instrumental analysis such as nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) of the binder resin or its hydrolyzate. Can be confirmed or estimated using the law.

  In the synthesis of the resin unit described above, a chain transfer agent for adjusting the molecular weight of the obtained resin may be further included in a raw material such as a monomer of the resin unit. A chain transfer agent may be used individually by 1 type, and may use 2 or more types together. Examples of the chain transfer agent include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, and styrene dimer.

  Here, the “graft bond” means a chemical bond between a polymer as a main chain and a different kind of polymer (or monomer) as a side chain. The hybrid crystalline polyester resin may have a structure in which a crystalline polyester resin unit is graft-bonded to an amorphous resin unit from the viewpoint of comprehensively improving desired properties of the toner.

  The contents of the crystalline polyester resin unit and the amorphous resin unit in the hybrid crystalline polyester resin can be appropriately determined within a range where the effects of the present embodiment can be obtained. For example, if the content of the amorphous resin unit in the hybrid crystalline polyester resin is too low, the dispersibility of the hybrid crystalline polyester resin in the toner base particles may be insufficient. May be insufficient. From such a viewpoint, the content is preferably 5 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint of improving high-temperature storage stability and charging uniformity.

  From the same viewpoint, the content of the crystalline polyester resin unit in the hybrid crystalline polyester resin is preferably 65 to 95% by mass, and more preferably 70 to 90% by mass. Moreover, the hybrid crystalline polyester resin may further contain components other than both units as long as the effects of the present embodiment can be obtained. Examples of other components include various additives to be added to other resin units and toner base particles.

  The toner base particles may contain other components such as a colorant, a release agent (wax), and a charge control agent.

(Coloring agent)
Examples of the colorant include carbon black, a magnetic material, a dye, and a pigment. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of the magnetic material include ferromagnetic metals such as iron, nickel, or cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite or magnetite. Examples of dyes include C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95, and mixtures thereof are included. Examples of pigments include C.I. I. Pigment Red 5, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, or a mixture thereof.

(Release agent)
As the release agent, various known waxes can be used. Examples of waxes include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, and dialkyls such as distearyl ketone. Ketone wax, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanedioldi Ester waxes such as stearate, trimellitic trimellitic acid, distearyl maleate, ethylenediamine behenylamide, trimellitic acid tristearylamide Include amide-based wax. 0.1-30 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of a mold release agent, 1-10 mass parts is more preferable. A mold release agent may be used individually by 1 type, and may use 2 or more types together. The melting point of the release agent is preferably from 50 to 95 ° C. from the viewpoint of low-temperature fixability and releasability of the toner.

(Charge control agent)
As the charge control agent, a known substance dispersed in an aqueous medium can be used. Examples of the charge control agent include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts, or metal complexes thereof.

(External additive)
The external additive includes alumina particles. Alumina is aluminum oxide represented by Al ₂ O ₃ . Alumina has forms such as α-type, γ-type, σ-type, and mixtures thereof. The shape of alumina can be selected by controlling the crystal system, and includes a cubic shape and a spherical shape. Alumina can be produced by a known method. As an example of alumina production method, buyer method is usually applied, but hydrolysis method, gas phase synthesis method, flame hydrolysis method, underwater spark discharge method are also applied to obtain high purity and nano-sized alumina. Can be done.

  The abundance of aluminum atoms on the surface of the toner particles is 0.80 atom% or more and 5.00 atom% or less, and preferably 1.50 atom% or more and 4.0 atom% or less. When the aluminum atom abundance ratio is within this range, the charge amount of the electrostatic image developing toner can be kept constant, and charges can be released during fixing. When the aluminum atom abundance ratio is less than 0.80 atom%, the charge is not sufficiently released when the electrostatic image developing toner is fixed. On the other hand, when the aluminum atom abundance ratio is more than 5.0 atom%, the charge holding ability of the electrostatic image developing toner is lowered.

  Here, “aluminum atom abundance ratio” means the abundance ratio of aluminum atoms on the toner particle surface. The aluminum atom abundance ratio was obtained by quantitatively analyzing all elements on the surface of the toner particles using an X-ray photoelectron spectrometer and calculating the concentration of each atom on the surface of the toner particles using a relative sensitivity factor from each atomic peak area. Value. Here, the “surface of the toner particle” means the outermost surface of the toner particle when measured using an X-ray photoelectron spectrometer under the conditions described later, and a range within 3 nm from the outermost surface.

  The number average primary particle diameter of the alumina particles is preferably 10 nm or more and 40 nm or less, and more preferably 15 nm or more and 30 nm or less. When the number average primary particle diameter of the alumina particles is less than 10 nm, the toner particles are easily embedded in the surface of the toner base particles due to collision with the carrier particles, and the charge amount is not stabilized or the charge is not stably discharged during fixing. Sometimes. On the other hand, when the number average primary particle diameter of the alumina particles is more than 40 nm, it is difficult to immobilize the toner particles on the surface of the toner base particles, which may cause the surface of the carrier particles to be contaminated and thereby deteriorate the image quality.

  The number average primary particle diameter of the alumina particles is obtained by taking a photographic image taken with a scanning electron microscope (SEM) (JSM-7401F; manufactured by JEOL Ltd.) with a scanner, and image processing analyzer (LUZEX AP; manufactured by Nireco). ) To binarize the alumina particles of the photographic image. Then, the horizontal ferret diameter is calculated for 100 alumina particles, and the average value is taken as the number average primary particle diameter.

  The surface of the alumina particles may be modified with a surface modifier. The surface-modified alumina particles have alumina particles and a surface modifier residue disposed on the surface of the alumina particles. The surface modifier includes a reaction part that reacts with the hydroxyl groups on the surface of the alumina particles and a non-reacting part that does not react with the hydroxyl groups on the surface of the alumina particles. By surface-modifying the alumina particles with a surface modifier, a surface modifier residue is arranged on the surface of the alumina particles. The surface modifier residue is generally an organic group. The structure of the surface modifier residue can be selected depending on the surface modifier selected. Examples of the surface modifier residue include an alkyl group, an aryl group, and an alkoxy group.

Examples of the surface modifier include silazane represented by the following formula (A) and a silane coupling agent represented by the following formula (B).
(R ₁ , R ₂ , R ₃ ) —Si—NH—Si— (R ₁ , R ₂ , R ₃ ) Formula (A)
_{(R 4) 4-n -Si-} (OR 5) n Formula (B)
R ₁ to R ₅ are each independently hydrogen, an alkyl group, an aryl group, or an alkoxy group, and may have a substituent, and R ₁ to R ₅ may be the same or different from each other. Good.

As the silazane, a known silazane can be used as long as the effect of the present embodiment is not impaired. Silazane is hexamethyldisilazane (in the above formula (A), R ₁ , R _2, and R ₃ are represented from the viewpoint of suppressing aggregation of the external additive particles and the reactivity with the surface of the external additive particles. Each is a methyl group) or hexaethyldisilazane (in the above formula (A), R ₁ , R ₂ and R ₃ are each an ethyl group), and hexamethyldisilazane is particularly preferred.

As the silane coupling agent, a known silane coupling agent can be used as long as the effect of the present embodiment is not impaired. The silane coupling agent preferably contains a linear alkyl group having 1 to 12 carbon atoms. The straight chain alkyl group may have a substituent. In the above formula (B), when R ₄ is an alkyl group having 1 to 12 carbon atoms, the external additive particles have an appropriate intermolecular force due to the interaction between the alkyl groups, and aggregation can be suppressed. . The number of carbon atoms of R ₄ is 4-8 is more preferable. When the number of carbon atoms in R ₄ exceeds 12, the cohesiveness increases and a sufficient effect is not exhibited. R ₅ in the above formula (B) is not particularly limited as long as the effect of the present embodiment can be obtained. Examples of R ₅ include a methyl group or an ethyl group. R ₅ is more preferably a methyl group from the viewpoint of reactivity, because the surface modification of the alumina particles becomes difficult when the functional group becomes three-dimensionally larger. In addition, when R ₅ is a hydrogen atom, the above formula (B) becomes a compound having a hydroxy group, so that the chemical affinity with water is increased. As a result, the charge amount in a high-temperature and high-humidity environment is increased. Since it becomes a leak point, it is not preferable.

When silazane is used as a surface modifier, the following structure can be generated through a deamination reaction with a hydroxyl group on the surface of alumina particles.
_{(Al * -O) 1 -Si (} -R 1, R 2, R 3)
[Al _* : Atoms on alumina surface]
When alkoxysilane (silane coupling agent) is used as the surface modifier, the following structure can be generated through hydrolysis and dehydration reaction.
_{(Al * -O) n -Si (} R 1) (OR 2) 3-n

  As a method for modifying the surface of the alumina particles, a known method can be adopted. Examples of the surface modification method include a dry method and a wet method.

  In the dry method, the alumina particles and the surface modifier are stirred or mixed in a fluidized bed reactor. In the wet method, first, alumina particles are dispersed in a solvent to form a slurry of alumina particles. Next, a surface modifier is added to the slurry to modify (hydrophobize) the surface of the alumina particles.

  At this time, the alumina particles and the surface modifier are preferably heated at 100 to 200 ° C. for 0.5 to 5 hours. By such heat treatment, the hydroxyl group on the alumina surface can be effectively modified. The amount of the surface modifier is not particularly limited, but is preferably 5 to 30 parts by mass and more preferably 8 to 20 parts by mass with respect to 100 parts by mass of the alumina particles.

The volume resistivity of the surface-modified alumina particles was determined by pressure-molding the surface-modified alumina particles at a pressure of 200 kg / cm ² to form pellets having a diameter of 20 mm and a thickness of 3.0 mm at 20 ° C. and 50%. The electrical resistance was measured using a digital LCR meter (4261A; manufactured by Japan Hewlett-Packard Co., Ltd.).

The volume resistivity of the surface-modified alumina particles is preferably 1.0 × 10 ⁸ Ω · cm to 1.0 × 10 ¹³ Ω · cm, and more preferably 1.0 × 10 ⁹ Ω · cm to 1.0 × 10. ¹¹ Ω · cm or less is more preferable. When the volume resistivity is less than 1.0 × 10 ⁸ Ω · cm, charge retention is lowered and the charge amount of the toner may be reduced. On the other hand, if it exceeds 1.0 × 10 ¹³ Ω · cm, it may be difficult to release charges during fixing.

  The volume resistivity of the alumina particles is preferably higher than the dynamic resistivity of carrier particles described later. When the volume resistivity of the alumina particles is lower than the dynamic resistivity of the carrier particles described later, there is a possibility that the charge amount is lowered when the charges are transferred to the carrier particles.

  Since the number average primary particle diameter of the surface-modified alumina particles can be almost the same as the number average primary particle diameter of the alumina particles that are not surface-modified, description thereof is omitted.

  The external additive may further contain silica particles in addition to the alumina particles. The silica particles can be produced by a known method such as a sol-gel method, a gas phase method (gas combustion method), or a melting method. The method for producing the silica particles is preferably a sol-gel method from the viewpoint of controlling the shape. The method for producing silica particles by the sol-gel method is a method in which tetraalkoxysilane is reacted in the presence of an alcohol containing an alkali catalyst while supplying tetraalkoxysilane and an alkali catalyst, respectively. The gas phase method is a method of vaporizing silicon chloride and synthesizing silica fine particles by gas phase reaction in a high-temperature hydrogen flame. In addition, the melting method is a process in which a mixed raw material composed of finely pulverized silica silica, a reducing agent such as metal silicon powder and carbon powder, and water for forming a slurry is heat-treated at a high temperature in a reducing atmosphere to generate SiO. This is a method obtained by quickly cooling in an atmosphere containing oxygen after generating gas.

  The number average primary particle diameter of the silica particles is preferably 70 nm or more and 150 nm or less. When the number average primary particle diameter of the silica particles is less than 70 nm, it is necessary to increase the transfer electric field for transferring the electrostatic image developing toner to the recording medium, and the transfer electric field makes the image itself easily charged. May stick. On the other hand, when the number average primary particle diameter of the silica particles exceeds 150 nm, the amount transferred to the surface of the carrier particles increases, and the stabilization of the charge amount and the stability of the toner flow characteristics may be impaired.

  The method for producing the electrostatic image developing toner is not particularly limited. Examples of the method for producing a toner for developing an electrostatic image include a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method. The production method of the electrostatic image developing toner is preferably an emulsion aggregation method from the viewpoint of uniformity of particle diameter and controllability of shape.

  In the emulsion aggregation method, a dispersion of binder resin particles (hereinafter, also referred to as “binder resin particles”) dispersed by a surfactant or a dispersion stabilizer is used as necessary. , Also referred to as “colorant particles”), and agglomerate until the desired toner particle diameter is obtained, and further, the shape is controlled by fusing the binder resin particles to form toner particles. It is a method of manufacturing. Here, the binder resin particles may optionally contain a release agent, a charge control agent, and the like. An example of obtaining toner particles having a core-shell structure using the emulsion aggregation method is shown below.

(1) Step of preparing a colorant particle dispersion in which colorant particles are dispersed in an aqueous medium (2) Resin in which binder resin particles containing an internal additive are dispersed in an aqueous medium as necessary Step of preparing particle dispersion (core / shell resin particle dispersion) (3) A colorant particle dispersion and a core resin particle dispersion are mixed to obtain an agglomeration resin particle dispersion. A process of agglomerating and fusing the colorant particles and binder resin particles in the presence of water to form agglomerated particles as core particles (aggregation / fusion process)
(4) A shell resin particle dispersion containing a binder resin particle for the shell layer is added to the dispersion containing the core particle, and the core layer particles are aggregated and fused on the surface of the core particle. -Process for forming toner base particles having a shell structure (aggregation / fusion process)
(5) A step of filtering the toner base particles from the dispersion of the toner base particles (toner base particle dispersion) to remove the surfactant, etc. (cleaning step)
(6) Step of drying toner base particles (drying step)
(7) A step of adding an external additive to the toner base particles (external additive treatment step).

  Toner particles having a core-shell structure are prepared by first aggregating and fusing binder resin particles for core particles and colorant particles. Next, the binder resin particles for the shell layer are added to the core particle dispersion, and the shell layer binder resin particles are aggregated and fused on the core particle surface to form a shell layer that covers the core particle surface. It is manufactured by doing. However, for example, in the step (4), toner particles formed from single-layer particles can be similarly produced without adding the shell resin particle dispersion.

  A mechanical mixing apparatus can be used for the external additive treatment step described above. Examples of the mechanical mixing device include a Henschel mixer, a Nauter mixer, and a Turbuler mixer. The external additive processing step may be performed by using a mixing device that can apply shearing force to the particles to be processed, such as a Henschel mixer, and by performing a mixing process such as increasing the mixing time or increasing the rotational peripheral speed of the stirring blade. . In addition, when using multiple types of external additives, all the external additives are mixed with the toner particles at once, or divided into multiple times according to the external additive and mixed. Also good. The external additive is mixed by using the mechanical mixing device described above to control the mixing strength, that is, the peripheral speed of the stirring blade, the mixing time, the mixing temperature, etc. Can be controlled.

<Configuration of two-component developer for developing electrostatic image>
The two-component developer for developing an electrostatic charge image has the above-described toner particles and carrier particles.

  Examples of the carrier particles include magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead. Examples of carrier particles include coated carrier particles having a core material particle made of a magnetic material, a coating portion having a coating material that covers the surface of the core material particle, and a fine powder of a magnetic material dispersed in a resin. And resin-dispersed carrier particles. The carrier particles are preferably coated carrier particles from the viewpoint of suppressing the adhesion of carrier particles to the photoreceptor.

  The core particle is, for example, a magnetic material that is strongly magnetized in the direction by a magnetic field. A magnetic body may be used individually by 1 type and may use 2 or more types together. Examples of the magnetic substance include metals exhibiting ferromagnetism such as iron, nickel and cobalt, alloys or compounds containing these metals, and alloys exhibiting ferromagnetism by heat treatment.

Examples of the metal exhibiting ferromagnetism or a compound containing the same include iron, ferrite represented by the following formula (a), and magnetite represented by the following formula (b). M in the formulas (a) and (b) represents one or more monovalent or divalent metals selected from the group consisting of Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd, and Li. Represent.
MO · _Fe 2 _{O 3} formula (a)
MFe ₂ O ₄ formula (b)

  Examples of alloys exhibiting ferromagnetism include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

  The core particles are preferably various ferrites. The specific gravity of the coated carrier particles is smaller than the specific gravity of the metal constituting the core particle. Therefore, various ferrites can make the impact force of stirring in the developing device smaller.

  The covering portion is disposed on the surface of the core material particles. The covering portion has a covering material. A coating material may be used individually by 1 type, and may use 2 or more types together. As the coating material, a known resin used for coating the core material particles on the carrier particles can be used. Examples of resins used as coating materials include polyolefin resins such as polyethylene and polypropylene; polystyrene resins; (meth) acrylic resins such as polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, and polyvinyl chloride. Polyvinyl resins and polyvinylidene resins such as: vinyl chloride-vinyl acetate copolymers and styrene-acrylic acid copolymers, etc .; silicone resins composed of organosiloxane bonds or modified resins thereof; fluorine such as polyvinyl fluoride Resin; Polyamide resin; Polyester resin; Polyurethane resin; Polycarbonate resin; Amino resin such as urea-formaldehyde resin; Examples of the modified resin include modified resins such as alkyd resin, polyester resin, epoxy resin, and polyurethane.

  The resin used as the coating material is preferably a resin having a cycloalkyl group from the viewpoint of reducing the moisture adsorptivity of the carrier particles and enhancing the adhesion with the core material particles in the coating portion. Examples of the cycloalkyl group include a cyclohexyl group, a cyclopentyl group, a cyclopropyl group, a cyclobutyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. The cycloalkyl group is preferably a cyclohexyl group or a cyclopentyl group, and more preferably a cyclohexyl group from the viewpoint of adhesion between the coating portion and the core particle.

The weight average molecular weight (Mw) of the resin having a cycloalkyl group is preferably 10,000 to 800,000, more preferably 100,000 to 750,000. Content of the structural unit containing the cycloalkyl group in the said resin is 10-90 mass%, for example. The content of the cycloalkyl group in the resin can be determined by a known instrumental analysis method such as P-GC / MS or ¹ H-NMR.

  The exposed area ratio of the core particles on the surface of the initial carrier particles is preferably 4.0% or more and 15.0% or less. Here, “initial” means a stage in which toner particles and carrier particles are mixed to produce a two-component developer for developing an electrostatic image. When the exposed area ratio is less than 4.0%, the resistance value of the carrier particles becomes too high, the electrostatic adhesion force between the carrier particles and the toner particles is increased, the toner particles are not easily replaced, and the fog and the image quality are deteriorated. May cause. On the other hand, when the exposed area ratio is more than 15.0%, the resistance value of the carrier particles themselves is lowered, so that the charge amount of the toner particles is lowered and image quality may be deteriorated.

  The exposed area ratio of the core particle on the surface of the carrier particle can be measured, for example, by the following method. An XPS measurement apparatus (K-Alpha; manufactured by Thermo Fisher Scientific) is used, an Al monochromatic X-ray is used as an X-ray source, an acceleration voltage is set to 7 kV, and an emission current is set to 6 mV. Next, carbon is measured as the main element constituting the coating layer, and iron is measured as the main element constituting the core particle. And the measurement result of carbon with respect to the measurement result of carbon and the measurement result of iron is taken as the exposed area ratio.

  The average particle diameter of the carrier particles is preferably 20 to 100 μm, more preferably 25 to 80 μm in terms of volume-based median diameter. The volume-based median diameter of the carrier particles can be measured by, for example, a laser diffraction particle size distribution measuring apparatus (HELOS; SYMPATEC) equipped with a wet disperser.

  The shape factor (SF-1) of the core particles is preferably 115 or more and 150 or less. When the shape factor is less than 115, the measured particle shape is close to a true sphere, so that the bulk density (g / cc) of the carrier is increased and the two-component developer for developing an electrostatic charge image is excessive in the development nip. It is easy for fogging and toner scattering to occur. On the other hand, when the shape factor is more than 150, the unevenness of the surface of the core material particles becomes severe, and voids are generated inside the core material particles. Therefore, the magnetization per core material particle is lowered, and the carrier particles themselves are developed on the photoconductor in the development nip portion, which may cause defects such as scratches on the surface of the photoconductor. A method for producing core material particles having a shape factor of about 115 to 150 can be obtained by setting the firing temperature to 1300 to 1500 ° C. higher than in the past in the firing step.

The shape factor is measured by using a scanning electron microscope, taking a photograph of 100 or more particles randomly at 150 times, and using the image processing analyzer LUZEX AP (Nireco Co., Ltd.). did. The shape factor (SF-1) of the core particle is obtained by the following formula (1).
SF-1 = (maximum length of particle) ² / (projected area of particle) × (π / 4) × 100 Formula (1)
The shape factor indicates the degree of unevenness of the core particle to be measured, and the value increases when the unevenness of the surface unevenness becomes severe.

The dynamic resistivity of the carrier particles is preferably 1.0 × 10 ⁸ Ω · cm or more and 1.0 × 10 ¹¹ Ω · cm or less. When the dynamic resistivity of the carrier particles is less than 1.0 × 10 ⁸ Ω · cm, the charge retention ability of the carrier particles themselves is lowered, and it may be difficult to maintain the charge amount of the toner particles. . On the other hand, when the dynamic resistivity of the carrier particles exceeds 1.0 × 10 ¹¹ Ω · cm, charges opposite to the toner particles on the carrier particles are accumulated, and the electrostatic adhesion between the toner particles and the carrier particles is caused. The adhesion is increased, and the toner particles are not easily replaced. As a result, fog and image quality degradation may occur.

The dynamic resistivity of the carrier particles is determined by replacing an aluminum electrode drum having the same dimensions as the photoconductor drum with a photoconductor drum, supplying carrier particles on the developing sleeve to form a magnetic brush, and using the magnetic brush as an electrode drum. By rubbing and applying a voltage (500 V) between the sleeve and the photosensitive drum and measuring the current flowing between them, the dynamic resistivity of the carrier particles was determined by the following equation (2).
DVR (Ω · cm) = (V / I) × (N × L / Dsd) Equation (2)
DVR: Carrier resistance (Ω · cm)
V: Voltage between developing sleeve and drum (V)
I: Measurement current value (A)
N: Development nip width (cm)
L: Development sleeve length (cm)
Dsd: Distance between the developing sleeve and the photosensitive drum (cm)
In Examples described later, measurement was performed with V = 500 V, N = 1 cm, L = 6 cm, and Dsd = 0.6 mm.

  Examples of the method for producing coated carrier particles having core material particles and a coating part include a wet coating method and a dry coating method. Examples of the wet coating include a fluidized bed spray coating method, a dip coating method, and a polymerization method.

  “Fluidized bed spray coating” is a method of spraying a coating solution in which a resin used as a coating material is dissolved in a solvent onto the surface of magnetic particles using a fluidized bed, and then drying to produce a coated part. It is a method to do. The “immersion-type coating method” is a method in which a magnetic particle is immersed in a coating solution in which a resin used as a coating material is dissolved in a solvent, applied, and dried to produce a coated portion. “Polymerization method” is a method in which a coating is prepared by immersing magnetic particles in a coating solution in which a reactive compound is dissolved in a solvent, followed by a polymerization reaction by applying heat or the like. .

  The “dry coating method” is a method in which a resin used as a coating material is attached to the surface of core particles, and then a mechanical impact force is applied to melt or soften the resin attached to the surface of core particles. And a covering part is produced. Specifically, the core material particles, the resin used as the coating material, and the low-resistance fine particles are stirred at a high speed using a high-speed stirring mixer that can impart mechanical impact force without heating or under heating. An impact force is repeatedly applied to the mixture, and a carrier fixed by dissolving or softening on the surface of the magnetic particles is produced. As a coating condition, in the case of heating, 80 to 130 ° C. is preferable, and the wind speed causing an impact force is preferably 10 m / s or more during heating, and 5 m / s from the viewpoint of suppressing aggregation of carrier particles during cooling. S or less is preferable. The time for applying the impact force is preferably 20 to 60 minutes.

  A two-component developer can be obtained by mixing the toner for developing an electrostatic image according to the present invention and carrier particles. It does not specifically limit as a mixing apparatus used in the case of mixing. Examples of the mixing device include a Nauter mixer, a W cone, and a V-type mixer. The toner particle content (toner concentration) in the two-component developer for developing an electrostatic image is not particularly limited, but is preferably 4.0 to 8.0% by mass.

  In the present embodiment, since the abundance ratio of aluminum atoms on the surface of the toner particles is 0.8 atom% or more and 5.0 atom% or less, the image quality can be maintained high even during continuous printing at a high printing rate. Sticking can be suppressed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

<Preparation of Black Colorant Fine Particle Dispersion BK>
90 parts by mass of sodium n-dodecyl sulfate was dissolved in 1600 parts by mass of ion-exchanged water with stirring. Next, 420 parts by mass of carbon black (Mogal L, pH 2 (room temperature 25 ° C.); manufactured by Cabot Corp.) was gradually added while stirring the solution. Next, a dispersion BK of fine black colorant particles in which carbon black particles were dispersed was prepared by performing a dispersion treatment using a stirrer (CLEAMIX; manufactured by M Technique Co., Ltd.). The particle diameter of the black colorant fine particles in this dispersion was measured using a Microtrac particle size distribution analyzer (UPA-150; Nikkiso Co., Ltd.), and the volume-based median diameter was 77 nm.

<Synthesis of crystalline polyester resin c1>
200 parts by mass of dodecanedioic acid and 102 parts by mass of 1,6-hexanediol are charged into a reaction vessel equipped with a stirrer, a nitrogen gas introduction tube, a temperature sensor, and a rectifying tower, and the temperature of the reaction system is increased to 190 over 1 hour. The temperature was raised to ° C. and it was confirmed that the reaction system was uniformly stirred. Next, 0.3 part by mass of titanium tetrabutoxide was added as a catalyst. Furthermore, the temperature of the reaction system was raised from 190 ° C. to 240 ° C. over 6 hours while distilling off the generated water. Further, the polymerization reaction was carried out by continuing the dehydration condensation reaction for 6 hours while maintaining the temperature at 240 ° C., to obtain a crystalline polyester resin c1. The obtained crystalline polyester resin c1 had a weight average molecular weight of 14,500 and a melting point of 70 ° C.

(Measurement of weight average molecular weight)
Using a GPC apparatus (HLC-8220; manufactured by Tosoh Corporation) and a column (TSKguardcolumn + TSKgelSuperHZM-M3; manufactured by Tosoh Corporation), tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0.2 mL / min while maintaining the column temperature at 40 ° C. Washed away. The weight average molecular weight was detected by injecting 10 μL of the sample solution into the apparatus and using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample was measured using monodisperse polystyrene standard particles. It calculated | required by calculating using a calibration curve.

(Measurement of melting point of crystalline polyester resin)
The melting point of the crystalline polyester resin was measured using a differential scanning calorimeter (Diamond DSC; manufactured by Perkin Elmer). First, 3.0 mg of crystalline polyester resin was sealed in an aluminum pan and set in a holder, and an empty aluminum pan was set as a reference. Next, a first temperature raising process for raising the temperature from 0 ° C. to 200 ° C. at a raising / lowering speed of 10 ° C./min, a cooling process for cooling from 200 ° C. to 0 ° C. at a cooling speed of 10 ° C./min, and a raising / lowering speed of 10 ° C./min The DSC curve was obtained by performing the second temperature raising process in which the temperature was raised from 0 ° C to 200 ° C. Next, based on this DSC curve, the maximum temperature of the endothermic peak derived from the crystalline polyester resin in the first temperature raising process was taken as the melting point.

<Production of crystalline polyester resin particle dispersion C1>
The obtained crystalline polyester resin c1 was dissolved in 100 parts by mass and 400 parts by mass of ethyl acetate. The solution was mixed with 638 parts by mass of an aqueous sodium dodecyl sulfate solution having a concentration of 0.26% by mass prepared in advance. While stirring the obtained mixture, ultrasonic dispersion treatment was performed for 30 minutes at 300 μA V-LEVEL using an ultrasonic homogenizer (US-150T; manufactured by Nippon Seiki Seisakusho Co., Ltd.). Next, using a diaphragm vacuum pump (V-700; manufactured by BUCHI) in a state heated to 50 ° C., ethyl acetate was completely removed while stirring for 3 hours under reduced pressure, to obtain a crystalline polyester resin particle dispersion. C1 was prepared. The crystalline polyester resin particles in the dispersion had a volume-based median diameter of 148 nm.

<Manufacture of styrene acrylic resin particle dispersion SP1 for core>
(First stage polymerization)
A reaction vessel equipped with a stirrer, temperature sensor, cooling pipe and nitrogen gas introduction device was charged with 4 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of ion-exchanged water. The temperature was raised to 80 ° C. Next, a solution in which 10 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added, the liquid temperature was again adjusted to 80 ° C., and a mixture of the following monomers was added dropwise over 2 hours.
Styrene 570.0 parts by mass n-butyl acrylate 165.0 parts by mass Methacrylic acid 68.0 parts by mass After the dropwise addition of the above mixture, polymerization is carried out by heating and stirring at 80 ° C. for 2 hours. A particle dispersion 1-a was prepared.

(Second stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing device was charged with a solution prepared by dissolving 3 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 1210 parts by mass of ion-exchanged water and heated to 80 ° C. did. After heating, 60 parts by mass of the styrene acrylic resin particle dispersion 1-a for core prepared in the first stage polymerization in terms of solid content and the following monomers, chain transfer agent and release agent are dissolved at 80 ° C. Was added.
Styrene (St) 245.0 parts by mass 2-ethylhexyl acrylate (2EHA) 97.0 parts by mass Methacrylic acid (MAA) 30.0 parts by mass n-octyl-3-mercaptopropionate 4.0 parts by mass Microcrystalline wax “ HNP-0190 "(manufactured by Nippon Seiwa Co., Ltd.)
170.0 parts by mass A mechanical dispersion machine having a circulation path (CLEARMIX; manufactured by M Technique Co., Ltd., “CLEARMIX” is a registered trademark of the company) is used for 1 hour of mixing and dispersing treatment to produce emulsified particles (oil droplets). A dispersion containing was prepared. A solution of a polymerization initiator obtained by dissolving 5.2 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water and 1000 parts by mass of ion-exchanged water were added to this dispersion, and the system was added at 84 ° C. for 1 hour. Polymerization was carried out by heating and stirring over time to prepare a styrene acrylic resin particle dispersion 1-b for core.

(3rd stage polymerization)
A solution prepared by dissolving 7 parts by mass of potassium persulfate in 130 parts by mass of ion-exchanged water was added to the styrene-acrylic resin particle dispersion 1-b for the core obtained by the second stage polymerization. Furthermore, the liquid mixture of the following monomer and chain transfer agent was dripped over 1 hour on 82 degreeC temperature conditions.
Styrene (St) 350 parts by weight Methyl methacrylate (MMA) 50 parts by weight N-butyl acrylate (BA) 170 parts by weight Methacrylic acid (MAA) 35 parts by weight n-octyl-3-mercaptopropionate 8.0 parts by weight After completion of the dropwise addition, polymerization was performed by heating and stirring for 2 hours, and then cooling to 28 ° C. to prepare a styrene acrylic resin particle dispersion SP1 for core. The styrene acrylic resin particles in the dispersion had a volume-based median diameter of 145 nm. Moreover, the weight average molecular weight of the obtained styrene acrylic resin was 35000, and the glass transition temperature (Tg) was 37 degreeC.

(Measurement of glass transition temperature)
The glass transition point is a value measured by a method (DSC method) defined in ASTM (American Society for Testing and Materials) D3418-82. Specifically, 4.5 mg of the sample was precisely weighed to two digits after the decimal point, sealed in an aluminum pan, and set in a sample holder of a differential scanning calorimeter (DSC8500; manufactured by Perkin Elmer). The reference uses an empty aluminum pan, and heat-cool-heat temperature control is performed at a measurement temperature of −0 to 120 ° C., a heating rate of 10 ° C./min, and a cooling rate of 10 ° C./min. . Analysis was performed based on the data in Heat. The glass transition temperature was defined as the value of the intersection of the base line extension before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rise portion of the first endothermic peak and the peak apex.

<Synthesis of Amorphous Polyester Resin d1>
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 360 parts by mass of bisphenol A propylene oxide 2-mol adduct, 80 parts by mass of terephthalic acid, 55 parts by mass of fumaric acid, and titanium tetraisopropoxy as a polycondensation catalyst. 2 parts by mass of the dough was divided into 10 portions and reacted at 200 ° C. for 10 hours while distilling off the water generated under a nitrogen stream. Subsequently, it was made to react under reduced pressure of 13.3 kPa (100 mmHg), and it took out when the softening point became 100 degreeC, and synthesize | combined amorphous polyester resin d1.

<Preparation of polyester resin particle dispersion D1>
100 parts by mass of the amorphous polyester resin obtained above was dissolved in 400 parts by mass of ethyl acetate. The solution was mixed with 638 parts by mass of an aqueous sodium dodecyl sulfate solution having a concentration of 0.26% by mass prepared in advance. While stirring the obtained mixed solution, ultrasonic dispersion treatment was performed for 30 minutes with 300 μA of V-LEVEL using an ultrasonic homogenizer.
Thereafter, in a state heated to 50 ° C., a diaphragm vacuum pump was used, and ethyl acetate was completely removed while stirring under reduced pressure for 3 hours to prepare an amorphous polyester resin particle dispersion D1. The volume-based median diameter of the amorphous polyester resin particles in the dispersion was 180 nm.

<Preparation of toner base particles 1 (aggregation / fusion process)>
In a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 435 g of the core resin fine particle SP1 dispersion (solid content conversion) and 15 g of the crystalline polyester resin particle dispersion C1 (solid content conversion) ), 1100 g of ion-exchanged water, and 50 g of a dispersion liquid of colorant fine particles BK, and the temperature of the obtained dispersion liquid was adjusted to 30 ° C. Next, 5N aqueous sodium hydroxide solution was added to the dispersion to adjust the pH of the dispersion to 10. Next, an aqueous solution in which 60 g of magnesium chloride was dissolved in 60 g of ion-exchanged water was added to the dispersion at 30 ° C. over 10 minutes with stirring. After the addition, the dispersion is kept at 30 ° C. for 3 minutes and then the temperature rise is started. The dispersion is heated to 85 ° C. over 60 minutes, and the particle growth reaction is carried out while keeping the temperature of the dispersion at 85 ° C. Then, a dispersion of pre-core particles 1 was prepared. 50 g of the resin fine particles D1 for shells (in terms of solid content) was added thereto, and stirring was continued for 1 hour at 80 ° C., and the shell resin fine particles D1 were fused to the surface of the core particles 1 to form a shell layer. To obtain resin particles 1. Here, an aqueous solution in which 150 g of sodium chloride is dissolved in 600 g of ion-exchanged water is added to the obtained dispersion, and aging treatment is performed at a liquid temperature of 80 ° C., and the average circularity of the resin particles 1 becomes 0.970. At that time, it was cooled to 30 ° C. The number-based median diameter of the toner base particles 1 after cooling was 5.5 μm.

<Preparation of toner base particles 2>
The toner base particles 2 are produced in the same manner as the toner base particles 1 except that the content of the dispersion of the core resin particles SP1 is 85% by mass and the content of the crystalline polyester resin is 5% by mass. did.

<Preparation of toner base particles 3>
Toner base particles 3 were prepared in the same manner as toner base particles 1 except that the content of the dispersion of core resin particles SP1 was changed to 80% by mass and the content of the crystalline polyester resin was changed to 10%. .

<Preparation of toner base particles 4>
Toner base particles 4 are produced in the same manner as toner base particles 1 except that the content of the dispersion of the core resin particles SP1 is 75% by mass and the content of the crystalline polyester resin is 15% by mass. did.

<Preparation of toner base particles 5>
Toner base particles 5 are produced in the same manner as toner base particles 1 except that the content of the dispersion of core resin particles SP1 is changed to 72% by mass and the content of the crystalline polyester resin is changed to 18% by mass. did.

<Preparation of toner base particles 6>
Toner base particles 6 were prepared in the same manner as toner base particles 1 except that the content of the dispersion of core resin particles SP1 was 90% by mass and no crystalline polyester resin was contained.

  Table 1 shows the amounts of the resins constituting the toner base particles 1 to 6.

<Preparation of external additive 1>
Aluminum trichloride (AlCl ₃ ) 320 kg / h was evaporated in an evaporator at about 200 ° C. and chloride vapor was passed through the burner mixing chamber with nitrogen. Here, the gas stream was mixed with hydrogen 100 Nm ³ / h and air 450 Nm ³ / h and fed to the flame via a central tube (diameter 7 mm). As a result, the burner temperature was 230 ° C., and the discharge speed of the tube was about 35.8 m / s. Hydrogen 0.05 Nm ³ / h was supplied as a jacket type gas via the outer tube. The gas combusted in the reaction chamber and was cooled to about 110 ° C. in the downstream agglomeration zone. There, agglomeration of primary particles of alumina was performed. The resulting aluminum oxide particles were separated from the hydrochloric acid-containing gas produced in a filter or cyclone, and the adhesive chloride was removed by treating the powder with wet air at about 500 to 700 ° C. Thus, alumina particles 1a were obtained.
The particle size of alumina can be adjusted by reaction conditions (for example, flame temperature, hydrogen or oxygen content), aluminum trichloride quality, residence time in the flame, or length of the agglomeration zone.
The obtained alumina particles 1a were put in a reaction vessel, and the surface modifier isobutyltrimethoxysilane 18g was diluted with 60g of hexane with respect to 100g of alumina powder while stirring the powder with a rotating blade in a nitrogen atmosphere. After heating and stirring at 200 ° C. for 120 minutes, the mixture was cooled with cooling water and dried under reduced pressure to obtain external additive 1 of alumina particles.

<Preparation of external additives 2 to 10>
The reaction conditions (flame temperature, hydrogen or oxygen content), aluminum trichloride quality, residence time in the flame or length of the agglomeration zone are appropriately changed, and the amount of surface modifier added is shown in Table 2. The external additives 2 to 10 were obtained in the same manner as the external additive 1 except that the amount was changed.

<Preparation of external additive 11>
347.4 g of pure water was weighed into an Erlenmeyer flask, 20 g of tetramethoxysilane (TMOS) was added with stirring, and the mixture was stirred as it was for 1 hour to prepare 364.4 g of a TMOS hydrolyzed solution. Next, 2250 g of pure water and 112 g of ethylenediamine were mixed in a 3 L reactor equipped with a stirrer, a dropping funnel, and a thermometer. This solution was adjusted to 35 ° C., and while stirring, half of the total amount of TMOS hydrolyzed liquid (182.2 g) was added at 2.5 mL / min. Subsequently, after maintaining in that state for 30 minutes, 4.5 g of a 1 mmol / g ethylenediamine aqueous solution was added to adjust the pH to 8 (35 ° C.). Thereafter, while appropriately adding an alkali catalyst (1 mmol / g ethylenediamine aqueous solution) so as to maintain pH 8 (35 ° C.), the remaining TMOS hydrolyzate was added at 2.5 mL / min every 3 hours, and this was continued. A total of 364.4 g was added. Even after the dropping of the TMOS hydrolyzed liquid was completed, the mixture was further stirred for 0.5 hours to perform hydrolysis and condensation, thereby obtaining a mixed medium dispersion of hydrophilic spherical silica particles. The obtained silica particles had a particle size (number average primary particle size) of 20 μm. Next, a solution in which 14.8 parts by mass of hexamethyldisilazane is mixed with 50 parts by mass of ethanol is prepared and sprayed onto 100 g of silica particles having a number average primary particle diameter of 20 nm obtained above by spray drying. The particles were surface modified. Next, the silica particles were heated to 80 ° C. to dry and remove ethanol, and then the silica particles were further subjected to surface modification while stirring at 250 ° C. for 2 hours to obtain an external additive 11.

<Preparation of external additives 12-17>
External additives 12 to 17 were added in the same manner as external additive 11 except that the amount of tetramethoxysilane (TMOS) added was 57 g, 68 g, 72 g, 79 g, 88 g, and 96 g, respectively. 12-17 were obtained.

<Preparation of external additive 18>
500 parts by mass of methanol was stirred in a 1 L reactor equipped with a stirrer, a dropping funnel, and a thermometer, 10 parts by mass of titanium isopropoxide was added dropwise, and stirring was continued for 15 minutes. Thereafter, the resulting titanium oxide fine particles were separated and collected by a centrifugal separator, and then dried under reduced pressure to obtain amorphous titanium oxide. The obtained amorphous titanium oxide was heated in the atmosphere at 800 ° C. for 5 hours in a high-temperature electric furnace to obtain rutile type titanium oxide fine particles. 100 parts by mass of the obtained rutile-type titanium oxide fine particles and 14.3 parts by mass of isobutyltrimethoxysilane are added to a 3 L reactor equipped with the above-described stirrer, dropping funnel, and thermometer, and stirred in toluene for 10 hours. The surface modification was performed on the surface of the rutile type titanium oxide fine particles. Thereafter, the reaction product was centrifuged to wash the reaction solvent, and then centrifuged again and collected, and dried under reduced pressure to obtain an external additive 18.

<Preparation of external additive 19>
An external additive 19 was obtained in the same manner as the external additive 18 except that the stirring time was 100 minutes.

  Table 2 shows the core material used, the number average primary particle diameter of the obtained external additive, the amount of the surface modifier used, and the volume resistance value of the obtained external additive.

<Production of Toner 1 (External Additive Treatment Process)>
The following external additives are added to the toner base particle 1 and added to a Henschel mixer (FM20C / I; manufactured by Nihon Coke Kogyo Co., Ltd.) so that the peripheral speed of the blade tip is 40 m / s and the rotation speed of the stirring blade And stirring for 15 minutes to prepare toner particles 1.
External additive 3 0.5 parts by mass External additive 14 2.4 parts by mass The temperature at which the external additive was mixed with the toner particles 1 was set to 40 ° C. ± 1 ° C. When the temperature reaches 41 ° C., the cooling water is supplied to the outer bath of the Henschel mixer at a flow rate of 5 L / min. When the temperature reaches 39 ° C., the flow rate of the cooling water is 1 L / min. In this way, the temperature inside the Henschel mixer was controlled by flowing cooling water.

<Preparation of Toners 2 to 6>
Toners 2 to 6 were obtained in the same manner as toner 1 except that the toner base particles were changed to toner base particles 2 to 6, respectively.

<Preparation of Toners 7 to 10>
The toner base particles were changed to toner base particles 3 and additive A was changed to No. Changed to 3. Also, toners 7 to 10 were obtained in the same manner as toner 1 except that the content of additive A was changed to 0.15, 0.20, 0.80, and 1.20 parts by mass, respectively.

<Preparation of Toners 11 and 12>
Toners 11 and 12 were obtained in the same manner as toner 1 except that external additive A was changed to external additives 11 and 18, respectively.

<Preparation of Toners 13 to 21>
Toners 13 to 21 were obtained in the same manner as Toner 1 except that external additive A was changed to external additives 1, 2, 4 to 10, respectively.

<Preparation of Toners 22 to 27>
External additive A was No. The external additive B was changed to No. 3. Toners 22 to 27 were obtained in the same manner as Toner 1 except that they were changed to 12, 13, 15 to 17, and 19, respectively.

  The abundance ratio of the aluminum ancestor on each toner particle surface was measured by the method described above.

  Table 3 shows the types of toner base particles, the types and contents of external additives, and the abundance ratio of aluminum atoms on the toner particle surfaces.

(Preparation of carrier particle 1)
Mn—Mg ferrite particles having a volume average diameter of 32 μm and a shape factor SF-1 of 145 were prepared as core material particles. 100 mass parts of the ferrite particles and 3.2 mass parts of the coating material are charged into a high-speed agitating mixer with a horizontal agitating blade, and the peripheral speed of the horizontal rotary blade is 8 m / sec. Mix and stir for 15 minutes. Then, it mixed at 120 degreeC for 50 minute (s), the coating material was coat | covered on the surface of the said core material particle | grain by the effect | action of a mechanical impact force (mechanochemical method), and the carrier particle 1 was produced. The median diameter based on volume distribution of the carrier particles 1 was 33 μm.

(Preparation of coating material 1)
In a 0.3% by weight aqueous solution of sodium benzenesulfonate, cyclohexyl methacrylate and methyl methacrylate are added at a molar ratio of 1: 1, and an amount of persulfuric acid corresponding to 0.5% by weight of the total amount of monomers is added. Emulsion polymerization was performed by adding potassium. The resin particles in the obtained dispersion liquid were dried by spray drying of the dispersion liquid, so that a covering material 1 as a core material coating resin was produced. The obtained coating material 1 had a weight average molecular weight (Mw) of 500,000. The weight average molecular weight (Mw) of the covering material 1 was determined by gel permeation chromatography (GPC).

(Preparation of carrier particles 2 to 6)
Carrier particles 2 to 6 are obtained in the same manner as the carrier particle 1 except that the content of the covering material 1 is changed to 4.2, 3.9, 2.9, 2.0, and 1.8 parts by mass, respectively. It was.

(Measurement of volume-based median diameter of carrier particles)
The volume-based median diameter of the magnetic particles was measured by a wet method using a laser diffraction particle size distribution analyzer (HELOS KA; manufactured by Nippon Laser Co., Ltd.). Specifically, first, an optical system with a focal position of 200 mm was selected, and the measurement time was set to 5 seconds. Then, the magnetic particles for measurement are added to a 0.2% sodium dodecyl sulfate aqueous solution and dispersed for 3 minutes using an ultrasonic cleaner (US-1; manufactured by AS ONE Co., Ltd.) to prepare a sample dispersion for measurement. Then, a few drops of this were supplied to the laser diffraction particle size distribution measuring device, and the measurement was started when the sample concentration gauge reached the measurable region. With respect to the obtained particle size distribution, a cumulative distribution was created from the smaller diameter side with respect to the particle size range (channel), and the particle size at which 50% of the accumulation was achieved was defined as the volume-based median diameter.

<Manufacture of two-component developer 1>
The toner 1 and the carrier particles 1 were mixed for 30 minutes with a V-type mixer so that the toner content (toner concentration) in the two-component developer was 6% by mass to obtain a two-component developer 1. .

<Production of two-component developer 2 to 27>
Two-component developers 2 to 27 were obtained in the same manner as the two-component developer 1 except that the toner was changed to toners 2 to 27, respectively.

<Manufacture of two-component developers 28 to 32>
Two-component developers 28 to 32 were obtained in the same manner as the two-component developer 1 except that the carrier particles were changed to carrier particles 2 to 6, respectively.

<Evaluation method>
As an evaluation apparatus, a commercially available digital full-color multifunction peripheral “bizhub PRESS 1070” (manufactured by Konica Minolta, “bizhub” is a registered trademark of the company) was used. Each of the produced two-component developers was loaded, and the following evaluation was performed. In this evaluation apparatus, printing was performed by an electrophotographic image forming method having a charging step, an exposure step, a development step, and a transfer step.

(Evaluation of image quality)
After printing 100,000 sheets of a solid band chart with a printing rate of 40% in an environment of 20 ° C. and 50% RH, an image of a gradation pattern with a gradation rate of 32 steps was output. Graininess in this image is evaluated by reading a gradation pattern with a CCD and subjecting the obtained read value to a Fourier transform process that takes Modulation Transfer Function (MTF) correction into consideration, and then applying a graininess that matches the human's relative visibility. Index (GI value) was measured to determine the maximum GI value. The smaller the GI value, the better, and the smaller the GI value, the smaller the granularity of the image. In addition, this GI value is a value published in Journal of the Imaging Society of Japan 39 (2), 84/93 (2000). And according to the following evaluation criteria, the granularity of the gradation pattern in the said image was evaluated about each of the evaluation apparatus after 100,000 durable printing. In the following criteria, “◎” or “◯” was determined to be acceptable.
◎: GI is less than 0.24 ○: GI is 0.24 or more and less than 0.26 ×: GI is 0.26 or more

(Evaluation of sticking force)
Twenty back solid images with an adhesion amount of 4.0 g / m ² are output (A3, OK top coat paper (manufactured by Oji Paper Co., Ltd.)), and 500 sheets of A3 J paper are printed on the output paper bundle. Placed for 2 hours. Placed on a flat table, tape was applied to the top of the top sheet and slowly slid horizontally. At this time, the sheet lower than the second sheet from the top is fixed to the table so as not to move. The force required to slide the paper was measured with a spring alone. This measurement was repeated in order from the top, and the average value of the force indicated only by the spring was defined as the sticking force. In the following criteria, “◎” or “◯” was determined to be acceptable.
A: Adhesion force is less than 1.2N. O: Adhesion force is 1.2N or more and less than 1.8N. X: Adhesion force is 1.8N or more.

  Table 5 shows the components of each two-component developer and the evaluation results of the obtained two-component developer.

  As shown in Table 5, toners 1 to 5 having toner base particles 1 to 5 containing a crystalline resin as a binder resin and 0.8 atom% ≦ aluminum atom existing ratio ≦ 5.0 atom%, In the two-component developers 1 to 5, 8, 9, and 13 to 32 having 8, 9, and 13 to 27, the image quality and the sticking force were sufficient.

  On the other hand, the two-component developer 6 that does not contain a crystalline resin as a binder resin does not have a sufficient sticking force. This is probably because the electrical resistance inside the image could not be lowered because it did not contain a crystalline resin.

  Further, the two-component developers 7 and 11 including the toners 7 and 11 in which the abundance ratio of aluminum atoms on the surface of the toner particles is less than 0.8 atom% did not have sufficient adhesion force. This is presumably because the charge could not be sufficiently discharged during toner fixing.

  Further, the image quality of the two-component developer 10 including the toner 10 in which the abundance ratio of aluminum atoms on the surface of the toner particles is more than 5.0 atom% is not sufficient. This is presumably because the charge could not be sufficiently discharged during toner fixing.

  In addition, the two-component developer 12 including the toner 12 using titania particles without using alumina particles as an external additive did not have sufficient adhesion force. It is considered that the titania particles are unevenly distributed in the toner image because the resistance value of the titania particles is lower than that of the alumina particles, and the charge cannot be discharged sufficiently.

  The image formed by the electrostatic charge image developing toner according to the present invention and the two-component developer for developing an electrostatic charge image containing the electrostatic charge image developing toner is high quality and has little sticking between recording media. . Therefore, according to the present invention, further popularization in an electrophotographic image forming method is expected.

Claims (6)

An electrostatic charge image developing toner having toner particles including toner base particles and an external additive disposed on the surface of the toner base particles,
The toner base particles include a crystalline resin as a binder resin,
The external additive includes alumina particles,
The abundance ratio of aluminum atoms on the surface of the toner particles is 0.8 atom% or more and 5.0 atom% or less.
Toner for developing electrostatic images.   2. The electrostatic image development according to claim 1, wherein the content of the crystalline resin is 5.0% by mass or more and 15.0% by mass or less based on the total amount of the binder resin contained in the toner base particles. toner.   The electrostatic charge image developing toner according to claim 1, wherein the number average primary particle diameter of the alumina particles is 10 nm or more and 40 nm or less. The alumina particles are surface modified with a surface modifier,
The volume resistivity of the surface-modified alumina particles is 1.0 × 10 ⁸ Ω · cm or more and 1.0 × 10 ¹³ Ω · cm or less.
The toner for developing an electrostatic charge image according to any one of claims 1 to 3. The external additive further includes silica particles,
The number average primary particle diameter of the silica particles is 70 nm or more and 150 nm or less.
The electrostatic image developing toner according to claim 1. An electrostatic image developing toner and carrier particles;
The carrier particles include core material particles and a covering portion disposed on the surface of the core material particles,
The exposed area ratio of the core particles is 4.0% to 15.0%,
The electrostatic charge image developing toner is the electrostatic charge image developing toner according to any one of claims 1 to 5.
Two-component developer for developing electrostatic images.