Toner, developer, toner storage unit, process cartridge, image formation method and image formation apparatus

Abstract

To provide a toner without worsening mixability with careers even when using an external additive having a polarity opposite to that of toner base particles.SOLUTION: A toner includes toner base particles and two kinds of external additives, external additive A and external additive B. The external additive A has a polarity opposite to that of the toner base particles; external additive B has a polarity the same as that of the toner base particles; and when the charge amount of the toner is set to A, the charge amount of the toner obtained from a dispersion prepared from the toner is set to B, and the charge amount of the toner obtained by imparting ultrasonic energy to the prepared dispersion is set to C, A, B and C satisfy the following relational expression (1): B<A<C (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner, a developer, a toner storage unit, a process cartridge, an image forming method, and an image forming apparatus. [Background technology]

[0002] Generally, toner is composed of toner base particles and external additives. By using the same toner base particles and changing the formulation of external additives, it is possible to create toner that is compatible with multiple processes. To do this, it is necessary to adjust the charge, and in that case, if you are aiming for a region with a lower charge than the toner base particles, it is effective to use an external additive with an opposite polarity. Patent Document 1 discloses a technique for externally adding negatively charged silica, titanium oxide, and positively charged silica to toner base particles in this order, which reduces the amount of external additives that are removed, allowing the chargeability to be maintained for a long period of time. Summary of the Invention [Problem to be solved by the invention]

[0003] However, when an external additive having an opposite polarity is used, there is a problem that the mixing property between the carrier and the toner deteriorates. An object of the present invention is to provide a toner that does not deteriorate in mixing with a carrier even when an external additive of opposite polarity is used. [Means for solving the problem]

[0004] The above problems can be solved by the following: A toner comprising toner base particles and two types of external additives, external additive A and external additive B, the external additive A has a polarity opposite to that of the toner base particles, the external additive B has the same polarity as the toner base particles, The charge amount of the toner is A, A dispersion liquid of the toner is prepared, and the charge amount of the toner obtained from the dispersion liquid is designated as B. When the toner dispersion liquid is prepared, and ultrasonic energy is applied to the dispersion liquid to obtain a toner having a charge amount C, The toner is characterized in that A, B, and C satisfy the following relational formula (1): B <A<C ···(1) [Effects of the Invention]

[0005] The toner of the present invention does not deteriorate in mixing with the carrier even when an external additive having an opposite polarity is used. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of an image forming apparatus of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the process cartridge of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention provides a toner comprising toner base particles and two types of external additives, namely, external additive A and external additive B, the external additive A has a polarity opposite to that of the toner base particles, the external additive B has the same polarity as the toner base particles, The charge amount of the toner is A, A dispersion liquid of the toner is prepared, and the charge amount of the toner obtained from the dispersion liquid is designated as B. When the toner dispersion liquid is prepared, and ultrasonic energy is applied to the dispersion liquid to obtain a toner having a charge amount C, The toner is characterized in that A, B, and C satisfy the following relational formula (1). B <A<C ···(1)

[0008] The method for measuring the charge amounts A, B, and C will be described later. The charge amount A indicates the charge amount of the toner itself. In addition, charge amount B indicates the charge amount when external additives that are weakly attached to the toner are removed, and charge amount C indicates the charge amount when external additives that are somewhat strongly attached to the toner are also removed.

[0009] When an external additive having an opposite polarity to that of the toner base particles is used, if this external additive having an opposite polarity to that of the toner base particles is present near the outermost surface of the toner including the external additive, it will repel the carrier and deteriorate the mixing ability. Therefore, it is preferable that the external additive having an opposite polarity is strongly attached to the base particles so that it does not become detached during the process. Charge amount B is the state where weakly adhering external additives have been removed, and more strongly represents the characteristics of external additives that are strongly adhering to the toner base particles. Charge amount C is the charge amount where strongly adhering external additives have also been removed, and more strongly represents the characteristics of the toner base particles. When external additives of opposite polarity are firmly adhering, the mixing is good, but in that case the relationship between the charge amounts is B. <A<Cとなる。

[0010] The toner base particles can be produced by any known method. The present invention will be described below by taking as an example a case where a solution suspension method is used as a method for producing toner base particles.

[0011] <Toner base particles> The toner base particles contain at least a binder resin and a release agent, and preferably contain a colorant and an inorganic filler, and may contain other components as required.

[0012] (binder resin) The binder resin preferably contains a crystalline resin and an amorphous resin (hereinafter, sometimes referred to as "amorphous resin").

[0013] -Crystalline resin- The crystalline resin is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include acrylic resin, styrene-acrylic resin, polyester resin, epoxy resin, etc. Among these, polyester resin (hereinafter referred to as crystalline polyester resin) is preferred.

[0014] The crystalline polyester resin has high crystallinity and exhibits a thermal melting property in which the viscosity drops sharply near the fixing start temperature, so the crystalline polyester does not melt until just before the melting start temperature, resulting in excellent heat-resistant storage stability. At the melting start temperature, the crystalline polyester resin melts, causing a sharp drop in viscosity, which allows it to become compatible with the amorphous resin and fix, resulting in a toner with excellent heat-resistant storage stability and low-temperature fixability. Furthermore, it is possible to obtain a toner having a large difference (release width) between the minimum fixing temperature and the temperature at which high-temperature offset occurs.

[0015] The crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose. For example, a polycondensation polyester resin synthesized from a polyhydric alcohol and a polycarboxylic acid can be used.

[0016] The polyhydric alcohol is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include diols, trihydric or higher alcohols, etc. These may be used alone or in combination of two or more.

[0017] The diol is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include saturated aliphatic diols.

[0018] Examples of the saturated aliphatic diol include linear saturated aliphatic diols and branched saturated aliphatic diols. Among these, linear saturated aliphatic diols are preferred because they increase the crystallinity of the crystalline polyester. Furthermore, linear saturated aliphatic diols having 2 to 12 carbon atoms are preferred because they are easily available.

[0019] Examples of the saturated aliphatic diol include ethylene glycol, 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, etc. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred because they increase the crystallinity of the crystalline polyester and provide excellent sharp melt properties.

[0020] Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0021] The polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include dicarboxylic acids and tricarboxylic or higher carboxylic acids.

[0022] The polycarboxylic acid may include a dicarboxylic acid having a sulfonic acid group, a dicarboxylic acid having a carbon-carbon double bond, and the like.

[0023] Examples of the dicarboxylic acid include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; and aromatic dicarboxylic acids such as dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid.

[0024] Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, and 1,2,4-naphthalenetricarboxylic acid.

[0025] The crystalline polyester resin preferably has a structural unit derived from a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a structural unit derived from a linear saturated aliphatic diol having 2 to 12 carbon atoms, which increases the crystallinity of the crystalline polyester, leading to excellent sharp melting properties and improved low-temperature fixability of the toner.

[0026] The melting point of the crystalline polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60° C. or higher and 90° C. or lower, and more preferably 60° C. or higher and 80° C. or lower. When the melting point is 60° C. or higher, the heat-resistant storage stability of the toner can be improved. When the melting point is 90° C. or lower, the low-temperature fixability of the toner can be improved.

[0027] The weight average molecular weight of the crystalline polyester resin is preferably 3,000 to 30,000, and more preferably 5,000 to 15,000. When the weight average molecular weight is 3,000 or more, the heat-resistant storage stability of the toner can be improved. When the weight average molecular weight is 30,000 or less, the low-temperature fixability of the toner can be improved.

[0028] The acid value of the crystalline polyester resin is preferably 5 mgKOH / g or more and 45 mgKOH / g or less, and more preferably 10 mgKOH / g or more and 45 mgKOH / g or less. When the acid value is 5 mgKOH / g or more, the low-temperature fixability of the toner can be improved. When the acid value is 45 mgKOH / g or less, the high-temperature offset resistance of the toner can be improved.

[0029] The hydroxyl value of the crystalline polyester is preferably 50 mgKOH / g or less, more preferably 5 mgKOH / g or more and 50 mgKOH / g or less. When the hydroxyl value is 50 mgKOH / g or less, the low-temperature fixability and charging characteristics of the toner can be improved.

[0030] The molecular structure of the crystalline polyester resin can be confirmed by NMR measurement using a solution or a solid, as well as by X-ray diffraction, GC / MS, LC / MS, IR measurement, and the like. Conveniently, in the infrared absorption spectrum, 965±10 cm -1 or 990±10cm -1 Crystalline polyesters can be detected as those that have absorption due to the δCH (out-of-plane bending vibration) of olefins.

[0031] -Amorphous resin- The amorphous resin is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include acrylic resin, styrene-acrylic resin, polyester resin, and epoxy resin. These may be used alone or in combination of two or more. Among these, polyester resins (hereinafter sometimes referred to as "amorphous polyester resins" or "amorphous polyesters") are preferred.

[0032] The amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose. For example, a polycondensation polyester resin synthesized from a polyhydric alcohol and a polycarboxylic acid can be used.

[0033] Examples of the polyhydric alcohol include dihydric diols and trihydric to octahydric or higher polyols.

[0034] The dihydric diol is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include aliphatic alcohols (dihydric aliphatic alcohols) such as linear aliphatic alcohols and branched aliphatic alcohols. These may be used alone or in combination of two or more. Among these, aliphatic alcohols having a carbon chain number of 2 to 36 are preferred, and linear aliphatic alcohols having a carbon chain number of 2 to 36 are more preferred.

[0035] The linear aliphatic alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ethylene glycol, 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, and 1,20-eicosanediol. Of these, ethylene glycol, 1,3-propanediol (propylene glycol), 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol are preferred in terms of availability. Among these, linear aliphatic alcohols having a carbon number of 2 to 36 are preferred.

[0036] The polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include dicarboxylic acids and tri- to hexa- or higher-valent polycarboxylic acids. Among these, polyvalent aromatic carboxylic acids are preferred.

[0037] The dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include aliphatic dicarboxylic acids and aromatic dicarboxylic acids.

[0038] Examples of the aliphatic dicarboxylic acid include linear aliphatic dicarboxylic acids, branched aliphatic dicarboxylic acids, etc. Among these, linear aliphatic dicarboxylic acids are preferred.

[0039] The aliphatic dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include alkanedicarboxylic acids, alkenylsuccinic acids, alkenedicarboxylic acids, and alicyclic dicarboxylic acids.

[0040] Examples of the alkanedicarboxylic acid include alkanedicarboxylic acids having 4 to 36 carbon atoms.

[0041] Examples of the alkanedicarboxylic acid having 4 to 36 carbon atoms include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, and decylsuccinic acid.

[0042] Examples of the alkenyl succinic acid include dodecenyl succinic acid, pentadecenyl succinic acid, and octadecenyl succinic acid. Examples of the alkene dicarboxylic acid include alkene dicarboxylic acids having 4 to 36 carbon atoms.

[0043] Examples of the alkene dicarboxylic acid having 4 to 36 carbon atoms include maleic acid, fumaric acid, and citraconic acid.

[0044] Examples of the alicyclic dicarboxylic acid include alicyclic dicarboxylic acids having 6 to 40 carbon atoms.

[0045] Examples of the alicyclic dicarboxylic acid having 6 to 40 carbon atoms include dimer acid (dimerized linoleic acid).

[0046] The aromatic dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include aromatic dicarboxylic acids having 8 to 36 carbon atoms.

[0047] Examples of the aromatic dicarboxylic acid having 8 to 36 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid.

[0048] Examples of the trivalent to hexavalent or higher polycarboxylic acids include aromatic polycarboxylic acids having 9 to 20 carbon atoms.

[0049] Examples of the aromatic polycarboxylic acid having 9 to 20 carbon atoms include trimellitic acid and pyromellitic acid.

[0050] As the dicarboxylic acid or the trivalent to hexavalent or higher polycarboxylic acid, an acid anhydride or an alkyl ester having 1 to 4 carbon atoms of the above-mentioned compounds may be used.

[0051] Examples of the alkyl ester having 1 to 4 carbon atoms include methyl ester, ethyl ester, and isopropyl ester.

[0052] (mold release agent) The release agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the release agent include vegetable waxes (e.g., carnauba wax, cotton wax, Japan wax, rice wax), animal waxes (e.g., beeswax, lanolin), mineral waxes (e.g., ozokerite, cerusine), petroleum waxes (e.g., paraffin, microcrystalline, petrolatum), hydrocarbon waxes (e.g., Fischer-Tropsch wax, polyethylene wax, polypropylene wax), synthetic waxes (e.g., esters, ketones, ethers), and fatty acid amide compounds (e.g., 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride, etc.). Among these, hydrocarbon waxes such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, and polypropylene wax are preferred.

[0053] The melting point of the release agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60° C. or higher and 80° C. or lower. When the melting point is 60° C. or higher, the heat-resistant storage stability of the toner can be improved. When the melting point is 80° C. or lower, the high-temperature offset resistance of the toner can be improved.

[0054] The content of the release agent is not particularly limited and can be appropriately selected depending on the purpose, and is, for example, preferably 2% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 8% by mass or less. When the content of the release agent in the toner is 2% by mass or more, the high-temperature offset resistance and low-temperature fixability of the toner can be improved, and when it is 10% by mass or less, the heat-resistant storage stability of the toner can be improved and the occurrence of image fogging can be suppressed.

[0055] (external additives) The toner of the present invention contains at least two types of external additives, external additive A and external additive B. Examples of external additives include oxide particles such as silica particles, titania particles, alumina particles, titanium oxide particles, tin oxide particles, and antimony oxide particles, fatty acid metal salts such as zinc stearate and aluminum stearate, and fluoropolymer particles. Among these, silica particles, titania particles, titanium oxide particles, and alumina particles are preferred. In addition to external additive A and external additive B, multiple types of external additives can be used. It is preferable to subject these external additives to a surface treatment to adjust the chargeability.

[0056] The external additive A has an opposite polarity to the toner base particles, and the external additive B has the same polarity as the toner base particles. The polarity of the external additive can be adjusted by known surface treatment. In the examples described below, negatively charged toner base particles are used, but the present invention can also be applied to positively charged toner base particles.

[0057] A large specific surface area of the external additive means a small particle size. When the particle size of the external additive is small, the external additive can be attached to the toner mother particles so that it slightly sinks into them, and even when ultrasonic energy is applied, the external additive is less likely to separate from the toner matrix particles. Conversely, those with a large particle size (roughly 100 nm or more) are less likely to sink into the toner matrix particles, so they are easily detached even when the mixing intensity is increased. From the above, in order to satisfy the relationship of A < B, the BET specific surface area of the external additive A is preferably 90 m 2 / g or more, and more preferably 130 m 2 / g or more. Also, the BET specific surface area of the external additive A is preferably 200 m 2 / g or less. On the other hand, the BET specific surface area of the external additive B is preferably 45 m 2 / g or more and 130 m 2 / g or less.

[0058] For example, to make it negatively charged, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, trifluoropropyltrimethoxysilane, and dimethylpolysiloxane can be used. To achieve a positive charge, a surface treatment with an amino group is preferred, and among these, a silane coupling agent containing an aluminum group is preferred. Examples include N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0059] (Other ingredients) The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include colorants, charge control agents, cleaning improvers, and magnetic materials.

[0060] The colorant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the colorant include carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, and anthrazan yellow BG. L, Isoindolinone Yellow, Bengala, Red Lead, Cinnabar, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Faise Red, Parachloroorthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine, Prussian Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake,Examples of the pigments include malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, and lithopone. These pigments may be used alone or in combination of two or more.

[0061] The content of the colorant is not particularly limited and can be appropriately selected depending on the purpose, but is preferably from 1% by mass to 15% by mass, and more preferably from 3% by mass to 10% by mass.

[0062] The pigment may be used as a masterbatch by compounding with a resin. The resin is not particularly limited and can be appropriately selected depending on the purpose. Examples of the resin include polymers of styrene or its substitution products such as amorphous polyester, polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-α-chloromethacrylate copolymer. Examples of suitable styrene copolymers include styrene-based copolymers such as methyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, and aromatic petroleum resin. These may be used alone or in combination of two or more.

[0063] The masterbatch can be produced by mixing and kneading the resin and the pigment. At this time, an organic solvent can be used to enhance the interaction between the pigment and the resin. The masterbatch can also be produced by, for example, a flushing method. The flushing method involves mixing and kneading an aqueous pigment paste, a resin, and an organic solvent together to transfer the pigment to the resin, and then removing the water and organic solvent. In this case, the pigment wet cake can be used as is, so there is no need to dry the pigment.

[0064] The mixing and kneading device is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include high-shear dispersing devices such as a three-roll mill.

[0065] The cleaning property improver is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include fatty acid metal salts such as zinc stearate and calcium stearate, and polymer particles produced by soap-free emulsion polymerization such as polymethyl methacrylate particles and polystyrene particles. The volume average particle size of the polymer particles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.01 μm or more and 1 μm or less.

[0066] The magnetic material is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include iron, magnetite, and ferrite. From the viewpoint of color tone, the magnetic material is preferably a white material.

[0067] <Toner manufacturing method> The method for producing a toner includes a step of dissolving or dispersing a binder resin in an organic solvent to prepare an oil phase, and a step of dispersing the oil phase in an aqueous phase and granulating the oil phase, and preferably also includes an emulsification / desolvation step, a washing step, a surface treatment step, a drying step, etc.

[0068] The toner is preferably produced by emulsifying or dispersing an oil phase containing amorphous polyester A, and optionally crystalline polyester C, a release agent, a colorant, etc., in an aqueous medium.

[0069] The aqueous medium preferably contains dispersed resin particles. The aqueous medium is not particularly limited as long as it is a solvent miscible with water and can be appropriately selected depending on the purpose, and examples thereof include organic solvents, water, etc. These may be used alone or in combination of two or more. Among these, water is preferred.

[0070] The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include alcohol, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones. These may be used alone or in combination of two or more. Among these, ethyl acetate, toluene, xylene, benzene, methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferred, with ethyl acetate being more preferred.

[0071] The resin constituting the resin particles is not particularly limited as long as it can be dispersed in an aqueous medium, and can be appropriately selected depending on the purpose. Examples include vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. These may be used alone or in combination of two or more. Among these, vinyl resins, polyurethane resins, epoxy resins, and polyester resins are preferred because they are easy to obtain fine spherical resin particles.

[0072] As a method for emulsifying or dispersing an oil phase in the aqueous medium, there is no particular limitation, and it can be appropriately selected according to the purpose. For example, a method of adding an oil phase to an aqueous medium and dispersing it by a shearing force can be mentioned.

[0073] There is no particular limitation on the disperser used when emulsifying or dispersing the oil phase in the aqueous medium, and it can be appropriately selected according to the purpose. For example, a low-speed shearing type disperser, a high-speed shearing type disperser, a friction type disperser, a high-pressure jet type disperser, an ultrasonic disperser, etc. can be mentioned. Among these, since the particle size of the dispersion (oil droplets) can be controlled to 2 μm to 20 μm, a high-speed shearing type disperser is preferable.

[0074] In the method for producing the toner, after dispersing the oil phase in the aqueous phase, an organic solvent is removed to form toner mother particles. After forming the toner mother particles, an external additive and, if necessary, a charge control agent are added to the toner mother particles and mixed with a mixing mixer or the like to produce a toner. There is no particular limitation on the mixing mixer, and it can be appropriately selected according to the purpose. For example, commercially available devices such as an Ong mill (manufactured by Hosokawa Micron Corporation) and a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) can be mentioned.

[0075] As a method for making the relationship between the charge amounts A, B, and C be B < A < C, a method of performing external addition mixing in multiple steps, adding external additive A in the first step, and mixing external additive B and other external additives after the second step can be mentioned. At that time, it is preferable to increase the mixing intensity by, for example, increasing the mixing time or raising the mixing temperature in the first step. This is because by strongly mixing external additive A first, external additive B adheres firmly to the toner mother particles and does not come off under light stress. In this state, relatively more external additive A remains in terms of the charge amounts A and B, and the charge becomes lower than C. Also, since more of external additive B is removed in terms of the charge amount B than the charge amount A, the charge amount B becomes lower than A. In this state, external additive A does not exist on the outermost surface of the toner, and a toner that can suppress charging and has good miscibility with a carrier can be provided.

[0076] (developer) The developer in the present invention comprises at least the toner of the present invention and a carrier.

[0077] <Career> The carrier is not particularly limited and can be appropriately selected depending on the purpose, but is preferably one having a core material and a resin layer covering the core material.

[0078] -Core material- The material for the core material is not particularly limited and can be appropriately selected depending on the purpose. Examples include manganese-strontium-based materials with a magnetic field of 50 emu / g to 90 emu / g, manganese-magnesium-based materials with a magnetic field of 50 emu / g to 90 emu / g, high-magnetization materials such as iron powder with a magnetic field of 100 emu / g or more, and magnetite with a magnetic field of 75 emu / g to 120 emu / g or less, and copper-zinc-based low-magnetization materials with a magnetic field of 30 emu / g to 80 emu / g or less. Among these, high-magnetization materials such as iron powder with a magnetic field of 100 emu / g or more and magnetite with a magnetic field of 75 emu / g to 120 emu / g or less are preferred in terms of ensuring image density. Furthermore, copper-zinc-based low-magnetization materials with a magnetic field of 30 emu / g to 80 emu / g or less are preferred in terms of reducing the impact of the developer in a standing state on the photoreceptor and thus improving image quality. These materials may be used alone or in combination of two or more.

[0079] The volume average particle size of the core material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm or more and 150 μm or less, and more preferably 40 μm or more and 100 μm or less. When the volume average particle diameter is 10 μm or more, the amount of fine powder in the carrier is reduced, the magnetization per particle is improved, and carrier scattering can be suppressed.When the volume average particle diameter is 150 μm or less, the specific surface area is increased, toner scattering is suppressed, and reproducibility of solid areas in full color toners with many solid areas is excellent.

[0080] The content of the carrier in the developer is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 90 parts by mass or more and 98 parts by mass or less, and more preferably 93 parts by mass or more and 97 parts by mass or less, relative to 100 parts by mass of the two-component developer.

[0081] (Process cartridge) The process cartridge is a device that integrates at least an image carrier and a developing means, contains toner, and is detachably mountable to an image forming apparatus. The process cartridge may further include at least one selected from a charging means, an exposure means, and a cleaning means. By mounting the toner storage unit of the present invention in an image forming apparatus and forming an image using the toner of the present invention, it is possible to provide a toner having excellent strength and low-temperature fixability.

[0082] (Image forming device) Next, one embodiment of a method for forming an image using the image forming apparatus of the present invention will be described with reference to Fig. 1. Although a printer is shown as an example of the image forming apparatus of this embodiment, the image forming apparatus is not particularly limited as long as it is capable of forming an image using toner in a copier, facsimile, multifunction machine, or the like. The image forming apparatus includes a paper feed unit 210, a conveying unit 220, an image forming unit 230, a transfer unit 240, and a fixing unit 250. The paper feed section 210 includes a paper feed cassette 211 in which the paper P to be fed is stacked, and a paper feed roller 212 that feeds the paper P stacked in the paper feed cassette 211 one sheet at a time.

[0083] The conveying section 220 includes a roller 221 that conveys the paper P fed by the paper feed roller 212 toward the transfer section 240, a pair of timing rollers 222 that hold the leading end of the paper P conveyed by the roller 221 and wait, sending the paper to the transfer section 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P with the fixed color toner image onto a paper discharge tray 224.

[0084] The image forming section 230 includes, at a predetermined interval from left to right in the drawing, an image forming unit 180Y that forms an image using a developer containing yellow toner, an image forming unit 180C that uses a developer containing cyan toner, an image forming unit 180M that uses a developer containing magenta toner, an image forming unit 180K that uses a developer containing black toner, a charger 232, and an exposure unit 233. The exposure unit 233 has a light source 233a and a polygon mirror 233b. It should be noted that when referring to any one of the image forming units (180Y, 180C, 180M, 180K), it is referred to as the image forming unit.

[0085] The developer contains toner and carrier. The four image forming units (180Y, 180C, 180M, 180K) have substantially the same mechanical configuration, except for the developer used in each unit.

[0086] Here, a premix development method may be adopted as the development method, in which a premix developer in which toner and carrier are mixed in advance is replenished. In the premix development method, the excess carrier in the developing device is discharged as excess developer. This gradually refreshes the developer in the developing device. This can extend the replacement cycle associated with developer deterioration and eliminate the effort required for developer replacement.

[0087] Transfer unit 240 includes a drive roller 241, a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in the drawing as the drive roller 241 is driven, primary transfer rollers (244Y, 244C, 244M, 244K) that are provided opposite photoconductor 231 with intermediate transfer belt 243 in between, and secondary opposing roller 245 and secondary transfer roller 246 that are provided opposite with intermediate transfer belt 243 in between at the position where the toner image is transferred to paper. Also includes cleaning device 236 that removes residual toner remaining on the surface of photoconductor 231. Here, the photoconductor 231 is not particularly limited in structure, size, etc., and can be appropriately selected from known ones. The shape of the image carrier is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a drum shape and a belt shape. The material of the photoconductor is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors (OPC) such as polysilane and phthalopolymethine.

[0088] Examples of organic photoreceptors include laminated photoreceptors having a laminated structure in which a layer (charge generation layer) in which a charge generation material such as metal-free phthalocyanine, titanyl phthalocyanine, or gallium phthalocyanine is dispersed in a binder resin and a layer (charge transport layer) in which a charge transport material is dispersed in a binder resin are stacked on a support such as an aluminum drum, and single-layer photoreceptors having a single-layer photosensitive layer on a support in which both a charge generation material and a charge transport material are dispersed in a binder resin. In the single-layer type photoreceptor, a hole transport material and an electron transport material can be added to the photosensitive layer as charge transport materials. An undercoat layer may be provided between the support and the multilayer charge generating layer or the single-layer photosensitive layer.

[0089] In this embodiment, an elastic intermediate transfer belt can also be used as the intermediate transfer belt 243. As the elastic intermediate transfer belt, for example, one in which a flexible elastic layer is laminated on a rigid base layer that can provide relatively flexibility can be used. In order to prevent the intermediate transfer belt 243 from meandering, a guide member for preventing the intermediate transfer belt 243 from shifting may be provided on the inner peripheral surface of the intermediate transfer belt 243 .

[0090] The fixing unit 250 has a heater installed inside and is equipped with a fixing belt 251 that heats the paper P, and a pressure roller 252 that forms a nip by rotatably applying pressure to the fixing belt 251. This applies heat and pressure to the color toner image on the paper P, fixing the color toner image. The paper P with the fixed color toner image is discharged to a paper discharge tray 224 by a paper discharge roller 223, completing the series of image formation processes.

[0091] (Process cartridge) The process cartridge according to the present invention is molded to be detachably mountable to various image forming apparatuses, and includes at least an electrostatic latent image carrier that carries an electrostatic latent image, and developing means that develops the electrostatic latent image carried on the electrostatic latent image carrier with the developer of the present invention to form a toner image. The process cartridge may further include other means, if necessary.

[0092] The developing means includes at least a developer container that contains the developer of the present invention and a developer carrier that carries and transports the developer contained in the developer container. The developing means may further include a regulating member or the like for regulating the thickness of the developer carried.

[0093] 2 shows an example of a process cartridge according to the present invention. The process cartridge 110 has a photosensitive drum 10, a corona charger 58, a developing device 40, a transfer roller 80, and a cleaning device 90. Also, 95 denotes paper.

[0094] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" means parts by mass and "%" means % by mass.

[0095] (Synthesis of amorphous polyester A) A reaction vessel equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was charged with an ethylene oxide 2-mol adduct of bisphenol A (referred to as BisA-EO), a propylene oxide 3-mol adduct of bisphenol A (referred to as BisA-PO), terephthalic acid, and adipic acid. At this time, the molar ratio of BisA-PO to BisA-EO was 40 / 60, the molar ratio of adipic acid to terephthalic acid was 93 / 7, the molar ratio of hydroxyl groups to carboxyl groups was 1.2, and 500 ppm of titanium tetraisopropoxide was added relative to the total monomers. Next, the mixture was reacted at 230° C. for 8 hours, and then reacted under reduced pressure of 10 to 15 mmHg for 4 hours. Furthermore, 1 mol % of trimellitic anhydride was added to the total monomers, and the mixture was reacted at 180° C. for 3 hours to obtain [amorphous polyester A]. The [Amorphous Polyester A] had a glass transition temperature of 67° C. and a weight average molecular weight of 10,000.

[0096] (Synthesis of crystalline polyester C) Sebacic acid and 1,6-hexanediol were charged into a reaction vessel equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple. The molar ratio of hydroxyl groups to carboxyl groups was set to 0.9, and 500 ppm of titanium tetraisopropoxide was added to the total monomers. Next, the mixture was reacted at 180°C for 10 hours, and then heated to 200°C and reacted for 3 hours. Further, the reaction was carried out under a reduced pressure of 8.3 kPa for 2 hours to obtain [Crystalline Polyester C]. The [Crystalline Polyester C] had a melting point of 67° C. and a weight average molecular weight of 25,000.

[0097] <Masterbatch production> Using a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), 1,200 parts of water, 500 parts of carbon black Printex 35 (manufactured by Dexa), a colorant with a DBP oil absorption of 42 mL / 100 mg and a pH of 9.5, and 500 parts of [amorphous polyester A] were mixed, and then the mixture was kneaded using a two-roll mill at 150°C for 30 minutes. Next, after rolling and cooling, the mixture was pulverized using a pulverizer to obtain a master batch.

[0098] <Synthesis of wax dispersant> An autoclave reaction vessel equipped with a thermometer and a stirrer was charged with 480 parts of xylene and 100 parts of Sanwax 151P (manufactured by Sanyo Chemical Industries, Ltd.), a polyethylene having a melting point of 108°C and a weight-average molecular weight of 1,000, and the polyethylene was dissolved therein, followed by nitrogen substitution. Next, a mixture of 805 parts of styrene, 50 parts of acrylonitrile, 45 parts of butyl acrylate, 36 parts of di-t-butyl peroxide, and 100 parts of xylene was added dropwise over 3 hours while polymerization was carried out at 170°C and maintained for 30 minutes. The solvent was then removed to obtain a wax dispersant. The wax dispersant had a glass transition temperature of 65° C. and a weight average molecular weight of 18,000.

[0099] <Preparation of wax dispersion> A vessel equipped with a stirring rod and a thermometer was charged with 300 parts of paraffin wax HNP-9 (manufactured by Nippon Seiro Co., Ltd.) having a melting point of 75°C as a release agent, 150 parts of the wax dispersant, and 1,800 parts of ethyl acetate. Next, the temperature was raised to 80°C while stirring, and after maintaining the temperature for 5 hours, it was cooled to 30°C over 1 hour. Furthermore, using a bead mill, Ultraviscomill (manufactured by Imex Co., Ltd.), zirconia beads with a diameter of 0.5 mm were filled to 80% by volume, and dispersed under three-pass conditions to obtain a wax dispersion. At this time, the liquid feeding rate was set to 1 kg / h, and the peripheral speed of the disk was set to 6 m / s.

[0100] <Preparation of Crystalline Polyester Dispersion> A vessel equipped with a stirring rod and a thermometer was charged with 308 parts of the [Crystalline Polyester C] and 1900 parts of ethyl acetate. Next, the temperature was raised to 80°C while stirring, and after maintaining the temperature for 5 hours, it was cooled to 30°C over 1 hour. Furthermore, a bead mill, Ultraviscomill (manufactured by Imex Co., Ltd.), was used to fill zirconia beads with a diameter of 0.5 mm to 80% by volume, and dispersion was carried out under three passes to obtain a [crystalline polyester dispersion]. At this time, the liquid feeding rate was set to 1 kg / h, and the peripheral speed of the disk was set to 6 m / s.

[0101] <Preparation of external additive 1> BET specific surface area is approximately 90m 2 10 g of silica (Nippon Aerosil Co., Ltd. #90) was dispersed in 60 g of toluene, and 10% of 3-aminopropyltriethoxysilane was added to the silica, followed by dispersion and mixing for 15 minutes to bring the silica into contact with the silica. 10% of trifluoropropyltrimethoxysilane was then added to the silica, followed by dispersion and mixing to bring the silica into contact with the silica. The dispersion was distilled under reduced pressure, dried, and crushed to obtain [External Additive 1].

[0102] <Preparation of external additive 2> In the preparation of [External Additive 1], silica with a BET specific surface area of ​​approximately 130 m 2 [External additive 2] was obtained in the same manner as in the preparation of [External additive 1], except that the silica (#130 manufactured by Nippon Aerosil Co., Ltd.) was used instead.

[0103] <Preparation of external additive 3> In the preparation of [External Additive 1], silica with a BET specific surface area of ​​approximately 200 m 2 [External Additive 3] was obtained in the same manner as in the preparation of [External Additive 1], except that the silica was changed to silica (#200 manufactured by Nippon Aerosil Co., Ltd.) with a 1 / g content of silica.

[0104] <Preparation of external additive 4> BET specific surface area is approximately 130m 210 g of silica (Nippon Aerosil #130) was dispersed in 60 g of toluene, and 10% trifluoropropyltrimethoxysilane was added to the silica, followed by dispersion and mixing to bring the mixture into contact with the silica. The dispersion was distilled under reduced pressure, dried, and crushed to obtain [External Additive 4].

[0105] <Preparation of External Additive 5> In the preparation of [External Additive 4], silica with a BET specific surface area of ​​approximately 45 m 2 [External Additive 5] was obtained in the same manner as in the preparation of [External Additive 4], except that the silica (#45 manufactured by Nippon Aerosil Co., Ltd.) was used. Table 1 shows the polarity and BET specific surface area of ​​the external additives 1 to 5 obtained above.

[0106] [Table 1]

[0107] Example 1 <Preparation of oil phase> 500 parts of the wax dispersion, 705 parts of the crystalline polyester dispersion, 836 parts of the amorphous polyester A, and 100 parts of the masterbatch were placed in a container and mixed at 5,000 rpm for 60 minutes using a TK homomixer (manufactured by Tokushu Kika Co., Ltd.) to obtain an oil phase.

[0108] <Synthesis of vinyl resin dispersion> A reaction vessel equipped with a stirring rod and a thermometer was charged with 683 parts of water, 11 parts of Eleminol RS-30 (manufactured by Sanyo Chemical Industries, Ltd.), a sodium salt of the sulfate ester of an ethylene oxide adduct of methacrylic acid, 138 parts of styrene, 138 parts of methacrylic acid, and 1 part of ammonium persulfate, and the mixture was stirred at 400 rpm for 15 minutes to obtain a white emulsion. Next, the temperature in the system was raised to 75°C and the reaction was carried out for 5 hours, after which 30 parts of a 1% aqueous ammonium persulfate solution was added and the mixture was aged at 75°C for 5 hours to obtain a vinyl resin dispersion. The vinyl resin dispersion had a volume average particle size of 0.14 μm, which was measured using a laser diffraction / scattering particle size distribution measuring device LA-920 (manufactured by HORIBA Corporation).

[0109] <Preparation of aqueous phase> 810 parts of pure water, 83 parts of the vinyl resin dispersion, dodecyl diphenyl ether 37 parts of a 48.5% aqueous solution of sodium disulfonate, Eleminol MON-7 (manufactured by Sanyo Chemical Industries, Ltd.), 180 parts of sodium sulfate, and 90 parts of ethyl acetate were mixed and stirred to obtain a milky white aqueous phase.

[0110] <Emulsification / solvent removal> 1200 parts of the aqueous phase was added to the vessel containing the oil phase, and then mixed for 20 minutes at 13000 rpm using a TK homomixer to obtain an emulsified slurry. Next, the emulsified slurry was placed in a container equipped with a stirrer and a thermometer and heated at 30°C for 8 hours. After removing the solvent for 4 hours, the mixture was aged at 45°C to obtain a dispersed slurry.

[0111] <Cleaning> 100 parts of the above [dispersed slurry] was filtered under reduced pressure. Next, 100 parts of ion-exchanged water was added to the filter cake, and the mixture was mixed using a TK homomixer at 12,000 rpm for 10 minutes, followed by filtration (hereinafter referred to as washing step (1)). Furthermore, 100 parts of a 10% aqueous sodium hydroxide solution was added to the filter cake, and the mixture was mixed using a TK homomixer at 12,000 rpm for 30 minutes, followed by filtration under reduced pressure (hereinafter referred to as washing step (2)). Next, 100 parts of 10% hydrochloric acid was added to the filter cake, and the mixture was mixed at 12,000 rpm for 10 minutes using a TK homomixer, followed by filtration (hereinafter referred to as washing step (3)). Furthermore, 300 parts of ion-exchanged water was added to the filter cake, and the mixture was mixed at 12,000 rpm for 10 minutes using a TK homomixer, followed by filtration (hereinafter referred to as washing step (4)). At this time, the washing steps (1) to (4) were repeated three times, followed by filtration.

[0112] <Drying> After the surface treatment, the filter cake was dried at 45° C. for 48 hours using a circulating air dryer, and then sieved through a mesh with 75 μm openings to obtain toner base particles.

[0113] <Addition of external additives> Using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), the toner base particles were subjected to external addition treatment in two stages as follows. First stage of external addition mixing: 100 parts of the base particles and 0.2 parts of [external additive 1] were mixed at a peripheral speed of 40 m / s for 15 minutes. Second stage of external addition mixing: 1.5 parts of [External Additive 4] and 2.0 parts of [External Additive 5] were added and mixed at a peripheral speed of 40 m / s for 15 minutes.

[0114] (Evaluation method) <Toner pretreatment for measuring charge amounts B and C> Charge amount B: 60 mL of 0.5% sodium dodecyl sulfate aqueous solution was placed in a 100 mL screw bottle, and 3 g of toner was added thereto. The toner was then dispersed for 30 to 90 minutes until it was fully incorporated into the dispersion. The resulting slurry was centrifuged at 2000 rpm for 2 minutes, and the supernatant was removed. This was reslurried with 60 mL of pure water, washed, and filtered in the same manner as in the previous washing step to obtain the toner.

[0115] Charge amount C: 60 mL of 0.5% sodium dodecyl sulfate aqueous solution was placed in a 100 mL screw bottle, and 3 g of toner was added. The toner was then dispersed for 30 to 90 minutes until it was fully incorporated into the dispersion. The resulting slurry was subjected to 2 minutes of 80 W energy using an ultrasonic homogenizer, and then centrifuged at 2000 rpm for 2 minutes to remove the supernatant. This was reslurried in 60 mL of pure water, washed, and filtered in the same manner as in the previous washing step to obtain the toner.

[0116] <Measuring method for charge amounts A, B, and C> After conditioning the standard carrier N-01 of the Japan Society for Imaging Science and Technology at 23°C and 50% relative humidity for 24 hours or more, 0.7 g of toner and 10 g of carrier were placed in a 50 mL PE container and mixed for 1 minute at 280 rpm using a roll mill to prepare a developer. 0.3 g of this developer was measured by the blow-off method. The toner itself was used for measuring the charge amount A, and the toner subjected to the pretreatment was used for measuring the charge amounts B and C. The absolute values of the respective obtained values are defined as the charge amount A, the charge amount B, and the charge amount C. The charge amount of the toner itself was -33 (μC / g), the charge amount of the toner subjected to the pretreatment for the charge amount B was -28 (μC / g), the charge amount of the toner subjected to the pretreatment for the charge amount C was -38 (μC / g), the charge amount A was 33 (μC / g), the charge amount B was 28 (μC / g), and the charge amount C was 38 (μC / g).

[0117] <Method for Measuring BET Specific Surface Area> The BET specific surface area was measured using an automatic specific surface area / pore size distribution measuring device (TriStar 3000: manufactured by Shimadzu Corporation). Approximately 0.5 g of the sample was weighed and vacuum dried for 24 hours using a pretreatment smart prep (manufactured by Shimadzu Corporation) to remove impurities and moisture on the sample surface. The pretreated sample was set in TriStar 3000, and the relationship between the nitrogen gas adsorption amount and the relative pressure was determined. From this relationship, the BET specific surface area of the sample can be determined by the BET multipoint method.

[0118] <Method for Evaluating Mixability with Carrier> After conditioning the standard carrier N-01 of the Japan Society for Imaging Science and Technology at 23°C and 50% relative humidity for 24 hours or more, 0.7 g of toner and 10 g of carrier were placed in a 50 mL PE container and mixed for 10 seconds at 280 rpm using a roll mill to prepare a developer. 0.3 g of this developer was measured 5 times by the blow-off method, and the variation in toner concentration (wt%) was calculated and judged. 〔Evaluation Criteria〕 ○: The difference between the minimum and maximum values of the toner concentration is less than 0.05%. △: The difference between the minimum and maximum values of the toner concentration is 0.05% or more and less than 0.1%. ×: The difference between the minimum and maximum toner density is 0.1% or more

[0119] <Evaluation method for background stains> Using a RICOH IM C4500 manufactured by Ricoh Co., Ltd., 200,000 sheets of a chart with an image area ratio of 5% were continuously output, and the degree of background scumming in the image background was visually evaluated according to the following criteria. The results are shown in Table 2. [Evaluation criteria] ○: Background smearing occurs in the background of the image during image output, but this does not cause any problems in actual use. △: Background smearing occurs in the background of the image during image output, which is problematic for practical use. ×: Background smearing occurs in the background of the image from the beginning of image output, and there is a problem in practical use.

[0120] Table 2 shows the conditions for adding external additives, mixing conditions, and evaluation results for Examples 1 to 3 and Comparative Examples 1 to 5.

[0121] [Table 2]

[0122] As shown in Table 2 above, the toners of Examples 1 to 3 of the present invention have good mixability with the carrier and can reduce the occurrence of background scumming.

[0123] The present invention includes, for example, the following aspects. (1) A toner comprising toner base particles and two types of external additives, namely, external additive A and external additive B, the external additive A has a polarity opposite to that of the toner base particles, the external additive B has the same polarity as the toner base particles, The charge amount of the toner is A, A dispersion liquid of the toner is prepared, and the charge amount of the toner obtained from the dispersion liquid is designated as B. When the toner dispersion liquid is prepared, and ultrasonic energy is applied to the dispersion liquid to obtain a toner having a charge amount C, The toner is characterized in that A, B, and C satisfy the following relational formula (1): B <A<C ···(1) (2) The BET specific surface area of ​​the external additive A is 130 m 2 / g or more. (3) A developer comprising the toner according to (1) or (2) above and a carrier. (4) A toner storage unit containing the toner described in (1) or (2) above. (5) an electrostatic latent image carrier; a developing unit that develops an electrostatic latent image formed on the electrostatic latent image carrier using the toner described in (1) or (2) above or the developer described in (3) above to form a visible image, and A process cartridge is detachably mountable to the main body of an image forming apparatus. (6) an electrostatic latent image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier; a developing unit that develops the electrostatic latent image to form a visible image using the toner described in (1) or (2) above or the developer described in (3) above; a transfer unit that transfers the visible image onto a recording medium; a fixing unit that fixes the transferred image onto the recording medium; An image forming apparatus comprising: (7) an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier; a developing step of developing the electrostatic latent image to form a visible image using the toner described in (1) or (2) above or the developer described in (3) above; a transfer step of transferring the visible image onto a recording medium; a fixing step of fixing the transferred image on the recording medium; An image forming method comprising: [Explanation of symbols]

[0124] 10 Photosensitive drum 40 Developer 58 Corona charger 80 Transfer roller 90 Cleaning Device 95 Paper 110 Process cartridge 160Y Sub Hopper (Yellow) 160C Sub Hopper (Cyan) 160M Sub Hopper (Magenta) 160K Sub Hopper (Black) 180Y Image Forming Unit (Yellow) 180C Image Forming Unit (Cyan) 180M Image Forming Unit (Magenta) 180K Image Forming Unit (Black) 200 Image forming device 210 Paper feed section 211 Paper cassette 212 Paper feed roller 220 Conveyor 221 Laura 222 Timing roller 223 Paper ejection roller 224 Paper output tray 230 Image creation section 231Y Photoconductor drum (yellow) 231C Photoconductor drum (cyan) 231M Photoconductor Drum (Magenta) 231K Photoconductor Drum (Black) 232Y Charger (Yellow) 232C Charger (cyan) 232M Charger (Magenta) 232K Charger (Black) 233 Exposure device 233a light source 233bY Polygon Mirror (Yellow) 233bC Polygon Mirror (Cyan) 233bM Polygon Mirror (Magenta) 233bK Polygon Mirror (Black) 234Y Toner Bottle (Yellow) 234C Toner Bottle (Cyan) 234M Toner Bottle (Magenta) 234K Toner Bottle (Black) 236Y Cleaning Device (Yellow) 236C Cleaner (cyan) 236M Cleaner (Magenta) 236K Cleaning Tool (Black) 240 Transcription Unit 241 Drive roller 242 driven roller 243 Intermediate transfer belt 244 Primary transfer roller 244Y Primary Transfer Roller (Yellow) 244C Primary transfer roller (cyan) 244M Primary Transfer Roller (Magenta) 244K Primary Transfer Roller (Black) 245 Secondary opposing roller 246 Secondary transfer roller 250 Fixing unit 251 Fixing belt 252 pressure roller L Laser P paper [Prior art documents] [Patent documents]

[0125] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-219935

Claims

1. A toner comprising toner base particles and two types of external additives, namely, external additive A and external additive B, the external additive A has a polarity opposite to that of the toner base particles, the external additive B has the same polarity as the toner base particles, The charge amount of the toner is A, A dispersion of the toner is prepared, and the charge amount of the toner obtained from the dispersion is defined as B. When the toner dispersion liquid is prepared, and ultrasonic energy is applied to the dispersion liquid to obtain a toner having a charge amount C, The toner is characterized in that A, B, and C satisfy the following relational expression (1). B<A<C...(1)

2. The BET specific surface area of ​​the external additive A is 130 m ２ 2. The toner according to claim 1, wherein the toner has a molecular weight of 1 / g or more.

3. A developer comprising the toner according to claim 1 and a carrier.

4. A toner storage unit containing the toner according to claim 1 or 2.

5. an electrostatic latent image carrier; a developing unit that develops an electrostatic latent image formed on the electrostatic latent image carrier using the toner according to claim 1 or 2 or the developer according to claim 3 to form a visible image, A process cartridge is detachably mountable to the main body of an image forming apparatus.

6. an electrostatic latent image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image on the electrostatic latent image carrier; a developing unit that develops the electrostatic latent image to form a visible image using the toner according to claim 1 or 2 or the developer according to claim 3; a transfer unit that transfers the visible image onto a recording medium; a fixing unit that fixes the transferred image onto the recording medium; An image forming apparatus comprising:

7. an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier; a developing step of developing the electrostatic latent image to form a visible image using the toner according to claim 1 or 2 or the developer according to claim 3; a transfer step of transferring the visible image onto a recording medium; a fixing step of fixing the transferred image on the recording medium; An image forming method comprising:

Images