JP5151717B2 - Toner for electrostatic image development - Google Patents

Description

  The present invention relates to an electrostatic image developing toner used in an electrophotographic image forming method.

  Currently, a two-component developer composed of a carrier and a toner and a one-component developer composed of a toner are widely used as a developer used in an electrophotographic image forming method. As a toner used in such a developer, a pulverized toner produced by a pulverization method has been widely used in the past because there is a demand for a small particle size in order to improve the image quality of a toner image. . However, since less energy is required to reduce the particle size of the toner compared to the pulverized toner, and there is no problem such as generation of fine powder due to pulverization, a so-called polymerized toner produced by a polymerization method is used. It is considered useful. As the polymerized toner, for example, suspension polymerized toner and associative toner are known, and the associative toner is preferable in terms of easy shape control.

  The associative toner is formed by aggregating and fusing resin particles formed from a polymerizable monomer and, if necessary, particles of a toner constituent material such as a colorant using a metal salt as an aggregating agent. It consists of the association particle | grains (colored particle | grains) obtained by this. However, since the addition amount of the flocculant required in the aggregation / fusion process is large, particularly when the resin particles are made of a polymerizable monomer containing a polar group such as a carboxyl group, The metal salt derived from the flocculant adhering to the resulting associated particles cannot be easily removed even by washing treatment. Since the metal salt derived from the coagulant used in the aggregation / fusion process has high hygroscopicity, the resulting associative toner has high hygroscopicity as a result. In the case of being performed under high temperature and high humidity conditions, the chargeability is lower than that in the case of being performed under low temperature and low humidity conditions. Therefore, in the case of using associative toner as the toner, the toner charge amount varies depending on the environmental conditions in which the image forming process is performed. For this reason, when the image forming process is performed under high temperature and high humidity conditions, or when the number of printed sheets increases, for example, fog (image smear) or the like occurs or the image density decreases, and the image is stably high. There is a problem in that an image with high image quality cannot be obtained.

Then, the technique which solves the said subject by using a polymer flocculent is reported (patent documents 1, 2). Patent Document 1 describes a toner production method in which a polymer flocculant is crushed and added. Patent Document 2 uses an organic polymer flocculant, or a polymer flocculant and an inorganic polymer. A combination with a flocculant is described. However, the present situation is that a sufficient water content reduction and toner charge amount variation for solving the above problems have not been achieved.
JP 2002-323796 A JP 2003-31068 A

  The present invention provides an electrostatic charge image developing toner that has excellent charging stability with respect to the environment, has a relatively sharp particle size distribution, and can stably obtain a high-quality image without fogging or density reduction over a long period of time. The purpose is to provide.

  The present invention relates to an electrostatic image developing toner obtained by aggregating and fusing at least resin particles in an aqueous medium in the presence of an aggregating agent, and for developing an electrostatic image using polyethyleneimine as the aggregating agent. It relates to toner.

In the present specification, “aggregation” is used in a concept that the resin particles and the colorant particles or the like are intended to simply adhere. By “aggregation”, so-called aggregated particles (groups) are formed in which the constituent particles are in contact with each other, but the bonding due to melting of the resin particles or the like is not formed.
“Fusion” is used in a concept intended to form a bond due to melting of resin particles or the like in at least a part of the interface of the individual constituent particles in the aggregated particles.

The toner for developing an electrostatic charge image according to the present invention does not contain an inorganic flocculant such as a metal salt having a relatively high hygroscopic property, and the amount of adsorbed moisture of the toner can be reduced by aggregating with a polymer flocculant. In addition, it has excellent charging stability with respect to the environment and can reduce variations in toner charge amount due to environmental conditions. As a result, fogging and image density reduction can be effectively prevented even under high-temperature and high-humidity conditions.
In addition, among the polymer flocculants, the use of polyethyleneimine in which the cationic site of the polymer flocculant that provides cohesive force is structurally uniform makes it possible to promote stable aggregation of the resin particles. It is possible to obtain associated particles having a uniform distribution. As a result, the charge amount distribution becomes uniform, and fogging and image density reduction can be more effectively prevented.

  Hereinafter, the present invention will be described in detail. The electrostatic image developing toner according to the present invention (hereinafter simply referred to as toner) is produced by a production method having a step of aggregating and fusing at least resin particles in the presence of an aggregating agent in an aqueous medium. In this case, the toner particles are composed of associative toner particles in which polyethyleneimine is used as a flocculant. If necessary, the resin particles may be aggregated and fused together with the colorant particles to constitute toner particles.

  Polyethyleneimine is a polymer compound obtained by ring-opening polymerization of ethyleneimine, which may have a branched structure or a linear structure, preferably a polyethyleneimine having a branched structure is used. To do. Since the polyethyleneimine having a branched structure has a three-dimensional structure, the cation density that becomes a cohesive force can be made extremely high, so that the addition amount can be further reduced and a three-dimensional structure is taken. This is because the cation sites become more uniform, and the particle size distribution can be made even more uniform.

  The total amine value of polyethyleneimine is usually 100 to 2000 mgKOH / g, preferably 1000 to 2000 mgKOH / g. The total amine value is the amine value for all amino groups consisting of primary, secondary and tertiary amino groups.

で表されるものであり、少なくとも第３級アミノ基を有するために３次元構造を有するものである。構造式（１）において、第３級アミノ基はＡで表され、Ｂは第２級アミノ基、Ｃは第１級アミノ基である。 The polyethyleneimine having a branched structure is, for example, structural formula (1);

It has a three-dimensional structure because it has at least a tertiary amino group. In Structural Formula (1), the tertiary amino group is represented by A, B is a secondary amino group, and C is a primary amino group.

  The branched structure type polyethyleneimine preferably has a tertiary amino group content of 15 to 45%, particularly preferably 15 to 35%, from the viewpoint of increasing the cation density that is a cohesive force.

  The content ratio of the primary amino group in the branched structure type polyethyleneimine is usually 20 to 50%, preferably 30 to 40%, and the content ratio of the secondary amino group is usually 25 to 55%, preferably 35. ~ 45%. The total of the primary amino group, secondary amino group, and tertiary amino group is 100%.

The total amine value, the content of primary, secondary and tertiary amino groups can be measured by the following method.
(Measurement of total amine value)
This indicates the total amount of primary, secondary and tertiary amino groups, and is expressed in mg of potassium hydroxide equivalent to hydrochloric acid required to neutralize 1 g of the sample. The method for measuring the total amine value is as follows. About 1 g of a sample is precisely weighed (sample amount: Sg), 20 ml of toluene is added to dissolve it, 20 ml of isopropyl alcohol and a few drops of bromophenol blue solution are added, and a 1/10 N isopropyl alcohol solution (titer: f) is added. Titration and read titration to end point. (Titration: Aml) From this titration, the amine value is calculated by the following formula.
Total amine value (mgKOH / g) = (A × f × 0.1 × 56.108) / S

(Measurement of content of primary, secondary and tertiary amino groups)
The content ratio of primary, secondary and tertiary amino groups can be calculated by 13C-NMR measurement of polyethyleneimine. The 13C-NMR measurement can be performed using an FT NMR apparatus Lambda400 (manufactured by JEOL Ltd.). The ratio of the peak areas of the primary, secondary, and tertiary amino groups in the measured spectrum is defined as the ratio of each amino group.

The molecular weights of the branched structure type and the linear structure type polyethyleneimine are not particularly limited as long as the object of the present invention is achieved, and usually the number average molecular weight is preferably 300 to 70000, more preferably 500 to 5000.
In this specification, the number average molecular weight is a value measured by HLC-8220 GPC (manufactured by TOSOH).

The branched structure type polyethyleneimine is available as commercially available Epomin (registered trademark) SP-003, SP-006, SP-012, SP-018, SP-200, SP-1000 (manufactured by Nippon Shokubai Co., Ltd.).
The linear structure type polyethyleneimine is available as a commercially available polyethyleneimine (manufactured by Kanto Chemical Co., Inc.).

  The amount of polyethyleneimine added may be not less than the critical aggregation concentration, preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration. The amount of such polyethyleneimine added is usually 2 to 10% by weight, preferably 4 to 8% by weight, based on the total weight of the resin particles. As the polyethyleneimine, two or more types of polyethyleneimines having different molecular weights or viscosities may be used in combination, and in this case, the total amount thereof may be within the above range. In the present invention, an inorganic flocculant such as a metal salt is not required.

  The critical flocculation concentration is an index relating to the stability of the aqueous dispersion, and indicates a concentration at which flocculation occurs when a flocculant is added. This critical aggregation concentration varies greatly depending on the emulsified components and the dispersant itself. For example, a detailed critical aggregation concentration can be obtained by the method described in Seizo Okamura et al., “Polymer Chemistry 17,601 (1960) edited by Japan Society of Polymer Science”. Another method is to add the desired polyethylenimine concentration to the desired particle dispersion, measure the zeta potential of the dispersion, and critically aggregate the polyethylenimine concentration at which this value changes. It can also be determined as a concentration.

  The aqueous medium for aggregating and fusing the resin particles and, if necessary, the colorant particles refers to a material whose main component (50% by weight or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

  The resin particles can be prepared by polymerizing a polymerizable monomer in an aqueous medium by a granulation polymerization method such as an emulsion polymerization method. As the aqueous medium used for the preparation of the resin particles, the same aqueous medium used for agglomeration / fusion of the resin particles and the colorant particles used as necessary can be used.

  As a polymerizable monomer used for obtaining resin particles, a radical polymerizable monomer is an essential constituent component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.

  (1) Radical polymerizable monomer: The radical polymerizable monomer is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled. Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

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

Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.
Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.
Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.
Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.
Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.

  (2) Cross-linking agent: As the cross-linking agent, a radical polymerizable cross-linking agent may be added in order to improve the properties of the toner. Examples of the radical polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

  (3) Radical polymerizable monomer having acidic group or basic group: As the radical polymerizable monomer having acidic group or radical polymerizable monomer having basic group, for example, a carboxyl group-containing monomer And amine compounds such as sulfonic acid group-containing monomers, primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. As carboxyl group-containing monomers that are radical polymerizable monomers having acidic groups, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, maleic acid monooctyl ester Etc. Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like. These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.

  Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, N-diary Ammonium chloride, N, N-diallyl-ethyl ammonium chloride, and the like.

  In the present invention, as the radical polymerizable monomer, the radical polymerizable monomer having an acidic group or the radical polymerizable monomer having a basic group is 0.1 to 15% by weight of the whole monomer. The radical polymerizable crosslinking agent is preferably used in a proportion of 0.1 to 10% by weight based on the total radical polymerizable monomer, although it depends on the characteristics.

  For the purpose of adjusting the molecular weight of the resin particles, it is possible to use a commonly used chain transfer agent. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionate, terpinolene, carbon tetrabromide and α-methyl. Styrene dimer or the like is used.

  In the present invention, any radical polymerization initiator may be used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), A peroxide compound etc. are mentioned. Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, so that the polymerization temperature can be lowered and the polymerization time can be further shortened. As the polymerization temperature, any temperature may be selected as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator. For example, a range of 50 ° C. to 90 ° C. is used. However, in the case of using a polymerization initiator that starts at room temperature, for example, a hydrogen peroxide-reducing agent (ascorbic acid or the like) combination, it is possible to polymerize at room temperature or higher.

  In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used here, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.

  The binder resin comprising a polymer obtained by polymerizing the polymerizable monomer as described above preferably has a weight average molecular weight Mw of 1 to 150,000, as measured by GPC (gel permeation method), and has a molecular weight distribution. Mw / Mn is preferably 1.5 to 5.

  As a method for measuring the molecular weight of a resin by GPC, 1 cc of tetrahydrofuran (THF) is added to 0.5 to 5.0 mg (specifically 1 mg) of a measurement sample, and stirring is performed at room temperature using a magnetic stirrer or the like. Go and dissolve well. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. As GPC measurement conditions, the column is stabilized at 40 ° C., THF is allowed to flow at a flow rate of 1 cc per minute, and about 100 μl of a sample having a concentration of 1 mg / cc is injected for measurement. The column is preferably used in combination with a commercially available polystyrene gel column. For example, a combination of Shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK and TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.

  The resin particles may contain a crystalline substance having a releasing property which is a fixing property improving agent (hereinafter, also simply referred to as “release agent”) and / or a coloring agent (dye or pigment) as necessary. Good.

Examples of the release agent include polyolefin waxes such as polyethylene wax and polypropylene wax, branched chain hydrocarbon waxes such as microcrystalline wax, long chain hydrocarbon waxes such as paraffin wax and sazol wax, and distearyl ketone. Dialkyl ketone wax, carnauba wax, montan wax, behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerol tribehenate, 1,18-octadecane Ester wax such as diol distearate, tristearyl trimellitic acid, distearyl maleate, ethylenediamine behenylamide, tristearyl trimellitic acid Such as amide-based waxes such as de the like.

  The content of the release agent is usually 1 to 30% by weight, preferably 2 to 20% by weight, and more preferably 3 to 15% by weight in the whole toner.

  As the dye, 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, etc. can be used, and mixtures thereof can also be used.

  In the present invention, “resin particles containing a release agent and / or a colorant” are obtained by dissolving a release agent and / or a colorant in a polymerizable monomer and placing the resulting monomer solution in an aqueous medium. It can be obtained by dispersing and polymerizing this system.

  As a preferable polymerization method for obtaining resin particles containing a release agent and / or a colorant, a release agent and / or a coloration is carried out in an aqueous medium in which a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. A monomer solution obtained by dissolving an agent in a polymerizable monomer is formed into oil droplets (10 to 1000 nm) using mechanical energy to prepare a dispersion, and the resulting dispersion is dissolved in water. And a method of radical polymerization by adding a polymerizable polymerization initiator (hereinafter referred to as “mini-emulsion method” in this specification). Instead of adding a water-soluble polymerization initiator, or while adding the water-soluble polymerization initiator, an oil-soluble polymerization initiator may be added to the monomer solution.

  The dispersing machine for dispersing oil droplets by mechanical energy is not particularly limited, and a stirring device “CLEARMIX” (manufactured by M Technique Co., Ltd.) equipped with a rotor that rotates at high speed. Examples thereof include an ultrasonic disperser, a mechanical homogenizer, a manton gourin, and a pressure homogenizer. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

  The colorant particles that are agglomerated and fused together with the resin particles as needed can be used in a form in which the colorant is dispersed in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably, “CLEAMIX”, ultrasonic disperser, mechanical homogenizer, pressure disperser such as Manton Gorin and pressure homogenizer, sand grinder, Getzmann mill And medium type dispersers such as diamond fine mill. Moreover, as a surfactant used, the same thing as the above-mentioned surfactant can be mentioned.

  As the colorant, carbon black, a magnetic material, a dye, a pigment, and the like can be arbitrarily used. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, and the like are used. Magnetic materials include ferromagnetic metals such as iron, nickel and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism by heat treatment, For example, a kind of alloy called Heusler alloy such as manganese-copper-aluminum, manganese-copper-tin, chromium dioxide, or the like can be used.

  Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 93, 94, 138, 155, 156, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. The number average primary particle diameter varies depending on the type, but is preferably about 10 to 200 nm.

  A colorant whose surface is modified can also be used. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used. In addition, as a surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the reaction is performed by raising the temperature of the system. It is possible to use a technique in which the colorant is separated by filtration, washed and filtered repeatedly with the same solvent, and then dried.

  As an example of the method for producing the toner of the present invention, (1) a dissolution step of preparing a monomer solution by dissolving a release agent and / or a colorant in a polymerizable monomer, (2) obtained. A dispersion step of dispersing the monomer solution in an aqueous medium; (3) a dispersion of resin particles containing a release agent and / or a colorant by polymerizing the aqueous dispersion of the resulting monomer solution; (4) Polymerization step for preparing (latex), (4) The obtained resin particles are agglomerated and fused in the presence of the polyethyleneimine in an aqueous medium together with colorant particles as necessary to form associated particles (toner particles). (5) Fusing step to obtain (5), (5) Filtration / washing step of separating the resulting associated particles from the aqueous medium and washing away the surfactant from the associated particles, (6) (7) Drying process The external additive may include external additive adding step of adding to the associated particles.

  (1) Dissolution step: The method for dissolving the release agent and / or the colorant in the polymerizable monomer is not particularly limited. An oil-soluble polymerization initiator and other oil-soluble components can also be added to the monomer solution.

  (2) Dispersing step: The method of dispersing the monomer solution in the aqueous medium is not particularly limited, but a method of dispersing by mechanical energy is preferable, and particularly an interface having a concentration equal to or lower than the critical micelle concentration. It is preferable to disperse oil droplets of the monomer solution in an aqueous medium in which the activator is dissolved by utilizing mechanical energy, which is an essential aspect in the mini-emulsion method. Here, the disperser for dispersing oil droplets by mechanical energy is not particularly limited. For example, “CLEARMIX”, ultrasonic disperser, mechanical homogenizer, Manton Gorin, pressure homogenizer, etc. Can be mentioned. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

  (3) Polymerization step; In the polymerization step, a granulation polymerization method such as an emulsion polymerization method, a suspension polymerization method, or a seed polymerization method can be basically employed. An example of a preferred polymerization method is a mini-emulsion method, that is, a monomer solution is dispersed in oil droplets using mechanical energy in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved. Examples of the method include radical polymerization by adding a water-soluble polymerization initiator to the resulting dispersion.

  In the polymerization step, the polymerization reaction is performed in multiple stages to form composite resin particles that are formed of resins having different molecular weight distributions and have a molecular weight gradient formed toward the surface layer of the particles. A polymerization method can be used.

  “Composite resin particle” means that one or more coating layers made of a resin having a different molecular weight and / or composition from the resin forming the core particle are formed so as to cover the surface of the core particle made of resin. It is a resin particle having a multilayer structure. “Multi-stage polymerization method” means that a monomer (n + 1) is polymerized (n + 1 stage) in the presence of resin particles (n) obtained by polymerizing monomer (n) (n stage). And a coating layer (n + 1) comprising a polymer of the monomer (n + 1) (a resin having a different dispersion and / or composition from the constituent resin of the resin particle (n)) on the surface of the resin particle (n). For example, when the resin particle (n) is a core particle (n = 1), the “two-stage polymerization method” is used, and when the resin particle (n) is a composite resin particle (n ≧ 2) is a multi-stage polymerization method of three or more stages.

  As a preferred embodiment of the multistage polymerization method, a central part (core) formed from a high molecular weight resin, an intermediate layer formed from an intermediate molecular weight resin containing a release agent, and an outer layer (shell) formed from a low molecular weight resin And so-called three-stage polymerization method.

  In a toner composed of toner particles obtained by such a three-stage polymerization method, a release agent is contained only in an intermediate layer made of an intermediate molecular weight resin, so that excellent offset resistance / fixing by the intermediate molecular weight resin is achieved. In addition, the anti-offset property and anti-winding property imparted by the high molecular weight resin constituting the central portion and the suitable fixing property imparted by the low molecular weight resin constituting the outer layer are not impaired. Moreover, high crushing strength can be obtained by decreasing the molecular weight of the resin constituting each layer from the center to the outer layer.

  The three-stage polymerization method will be specifically described. First, a dispersion of resin particles (H) obtained by a polymerization process (first stage polymerization) according to a conventional method is used as an aqueous medium (an aqueous solution of a surfactant). Along with the addition, a monomer solution obtained by dissolving a release agent in the polymerizable monomer (M) is dispersed in oil in the aqueous medium, and then this system is polymerized (second stage polymerization). By doing so, a coating layer (M) (intermediate layer) made of a resin (polymer of the polymerizable monomer (M)) containing a release agent is formed on the surface of the resin particles (H) (core particles). A dispersion of formed composite resin particles [high molecular weight resin (H) -intermediate molecular weight resin (M)] is prepared. Next, a polymerization initiator and a polymerizable monomer (L) for obtaining a low molecular weight resin are added to the resulting dispersion of composite resin particles, and a polymerizable monomer in the presence of the composite resin particles. By subjecting the body (L) to a polymerization treatment (third stage polymerization), a coating layer (L) made of a low molecular weight resin (polymer of the polymerizable monomer (L)) is formed on the surface of the composite resin particles. Form. In this way, composite resin particles composed of a central portion (core) formed from a high molecular weight resin, an intermediate layer containing a release agent, and an outer layer (shell) formed from a low molecular weight resin are produced. Is done.

  (4) Aggregation / fusion process: In the aggregation / fusion process, if necessary, a dispersion of colorant particles is added to the dispersion of resin particles obtained by the polymerization process, and the resin particles are dispersed in an aqueous medium. In the middle, it is agglomerated and fused in the presence of the polyethyleneimine flocculant. The content of the resin particles in the aqueous medium at the time of aggregation / fusion is not particularly limited, and is usually 5 to 20% by weight, particularly 10 to 15% by weight based on the total amount of all components contained in the aqueous medium. % Is preferred.

  Usually, as a fusing method, in the aqueous medium in which the resin particles and the colorant particles are present, the polyethyleneimine is added as an aggregating agent, and then heated to a temperature higher than the glass transition point of the resin particles. A technique is used in which the particles are agglomerated and fused at the same time. In such a fusion method, an organic solvent that is infinitely soluble in water may be added, and an agglomeration aid composed of, for example, slaked lime, soda ash, bentonite, fly ash, kaolin and the like can be used.

  Examples of the organic solvent that is infinitely soluble in water include methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, glycerin, acetone, and the like, but methanol, ethanol, 1-propanol, 2-carbon having 3 or less carbon atoms. Alcohol of propanol is preferable, and 2-propanol is particularly preferable.

  In the fusing step, it is preferable to make the time allowed to stand after adding the flocculant (time until heating is started) as short as possible. That is, after adding the flocculant, it is preferable to start heating the dispersion of the resin particles and the colorant particles as quickly as possible so that the temperature is equal to or higher than the glass transition temperature of the resin particles. The reason for this is not clear, but the aggregation state of the particles fluctuates with the elapse of the standing time after agglomeration, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. This is because. The time (starting time) until the heating is started is usually within 30 minutes, preferably within 10 minutes. The temperature at which the flocculant is added is not particularly limited, but is preferably not higher than the glass transition temperature of the resin particles.

  Moreover, in the fusion | melting process, it is necessary to heat up rapidly by heating, and it is preferable that a temperature increase rate shall be 1 degree-C / min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of fusion. Furthermore, after the dispersion of the resin particles and the colorant particles reaches a temperature equal to or higher than the glass transition temperature, it is important to continue the fusion by maintaining the temperature of the dispersion for a certain time. As a result, toner particle growth (aggregation of resin particles and colorant particles) and fusion (disappearance of the interface between the particles) can be effectively advanced, and the durability of the finally obtained toner can be improved. Can be improved. Moreover, after stopping the growth of the associated particles, an aging treatment may be performed in which fusion by heating and stirring is continued in a temperature range of the melting point of the release agent ± 20 ° C.

  In the fusing step, internal additive particles such as a charge control agent can be fused together with the resin particles and the colorant particles. Furthermore, the resin particles not containing these can be fused together with the resin particles containing the release agent.

  In the fusing step, after forming fused particles by agglomeration and fusing, new resin particles may be added to form a shell layer made of the resin particles on the surface of the fused particles.

  (5) Filtration / washing step: In this filtration / washing step, a filtration treatment for separating the toner particles from the dispersion of toner particles obtained in the above-mentioned step, and a filtered toner particle (cake-like aggregate) And a cleaning process for removing deposits such as surfactants from the product. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(6) Drying step; This step is a step of drying the washed toner particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. Water content W _H of dried toner particles is preferably 1.0 wt% or less, still more preferably 0.5 wt% or less.

The water content of the toner particles can be measured by the Karl Fischer method.
Specifically, automatic thermal vaporization moisture measurement system AQS-724 (Hiranuma Sangyo) consisting of moisture meter (AQUACOUNTER) AQ-6, AQI-601 (interface for AQ-6), heating vaporizer (AUTOMATED SOLID EVAPOATOR) LE-24S (HIRANUMA SANGYO Co., Ltd.) is used. After 0.5 g of the sample to be measured is allowed to stand for 24 hours under an environmental condition in which the temperature and humidity are adjusted, it is precisely weighed into a 20 ml glass sample tube and then sealed with a Teflon-coated silicone rubber packing. In order to correct the moisture present in the sealed environment, two empty samples are measured simultaneously. Measurement conditions and reagents are as follows.
Sample heating temperature: 110 ° C
Sample heating time: 1 minute Nitrogen gas flow rate: 150 ml / min Reagent: HYDRANAL®-Culomat CG-K and HYDRANAL®-Culomat AK
Counter electrode liquid (catholyte): Hydranal Coulomat CG-K (HYDRANAL (registered trademark)-Coulomat CG-K)
Generation liquid (anolyte): Hydranal Coulomat AK (HYDRANAL (registered trademark)-Coulomat AK)
The temperature 30 ° C., the amount of water is measured in 24-hour standing toner particles in an environment of high temperature and high humidity RH 85% humidity and the water content W _H of the toner particles, the temperature 10 ° C., the sample tone RH humidity 30% the amount of water measured in 24-hour standing toner particles in low-temperature and low-humidity environment of humidity conditions was water amount W _L of the toner particles.

  When the dried toner particles are aggregated with a weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

  (7) External additive addition step; This step is a step of adding an external additive to the dried toner particles. Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

  The toner can be used with so-called external additives added for the purpose of improving fluidity and chargeability and improving cleaning properties. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used. As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania and alumina, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. . The degree of the hydrophobization treatment is not particularly limited, but those having methanol wettability of 40 to 95 are preferable. Here, methanol wettability is an evaluation of wettability to methanol. In this method, 0.2 g of inorganic fine particles to be measured are weighed and added to 50 ml of distilled water placed in a beaker having an internal volume of 250 ml. Methanol is slowly dropped from a burette whose tip is immersed in a liquid, with slow stirring until the entire inorganic fine particles are wet. When the amount of methanol necessary to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following formula.

    Hydrophobicity = [a / (a + 50)] × 100

As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As the organic fine particles, homopolymers such as styrene and methyl methacrylate and copolymers thereof can be used.
Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The addition ratio of the external additive is 0.1 to 5.0% by weight, preferably 0.5 to 4.0% by weight with respect to the toner particles. In addition, various external additives may be used in combination.

  The toner used in the present invention may be added with materials capable of imparting various functions as toner materials in addition to the colorant and the release agent. Specific examples include charge control agents. These components can be added at the same time as the resin particles and the colorant particles in the above-described fusing step, and can be added by various methods such as a method of inclusion in the toner and a method of adding to the resin particles themselves. Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples 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.

  The toner as described above is an association type toner obtained by aggregating and fusing resin particles and, if necessary, colorant particles in an aqueous medium, and is obtained by using a polyethyleneimine flocculant. Therefore, the hygroscopicity is reduced, and as a result, the charge amount when the image forming process is performed under a high temperature and high humidity condition may be smaller than the charge amount when the image forming process is performed under a low temperature and low humidity condition. It is suppressed. Accordingly, it is possible to stably form a high quality image. Further, according to the toner production method using the polyethyleneimine flocculant, the particle size distribution becomes relatively sharp, so that selective development is suppressed, and fogging and image density reduction can be prevented even during long-term use. .

  The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, or can be mixed with a carrier and used as a two-component developer. When this toner is used as a non-magnetic one-component toner, a developer having a configuration in which a developer layer regulating member for forming a thin layer is suppressed by a developer layer carrier is used. Development is performed with the developer layer on the body in contact or non-contact with the electrostatic charge image carrier. A preferred method is contact development.

  When used as a two-component developer, as a carrier constituting the two-component developer, conventionally known metals such as iron, ferrite, magnetite, and alloys of these metals with metals such as aluminum and lead Materials can be used. Ferrite particles are particularly preferable. The volume average particle diameter of the carrier is preferably 15 to 100 μm, more preferably 25 to 60 μm. The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  Preferred carriers include a resin-coated carrier in which the surface of magnetic particles is coated with a resin, and a so-called resin-dispersed carrier in which magnetic particles are dispersed in a resin. The resin constituting the resin-coated carrier is not particularly limited, and for example, olefin resin, styrene resin, styrene / acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. The resin for constituting the resin-dispersed carrier is not particularly limited, and known resins can be used. For example, styrene acrylic resin, polyester resin, fluorine resin, phenol resin, etc. can be used. it can.

  The development method applied in such a two-component developer is not particularly limited, and can be suitably used for both the contact development method and the non-contact development method.

  The developer develops the latent image formed on the electrostatic latent image bearing member with the developer, visualizes it, transfers the toner to the transfer material, and transfers the transfer material on which the toner image is formed to the fixing device. It is suitably used in an image forming method including a step of fixing by passing between a heating roller and a pressure roller.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, “parts” means “parts by weight”.

<Example 1>
[Preparation Example 1 of Resin Particles]
(1) Formation of core particles (first stage polymerization): In a 5000 ml separable flask equipped with a stirrer, a temperature sensor, a condenser tube, and a nitrogen introducing device, the following formula (a);
_{C 10 H 21 (OCH 2 CH} 2) 2 OSO 3 Na (a)
A surfactant solution (aqueous medium) in which 7.08 g of an anionic surfactant represented by the following formula (hereinafter also referred to as “anionic surfactant (1)”) is dissolved in 3010 g of ion-exchanged water is charged, and nitrogen is added. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under an air stream. To this surfactant solution, an initiator solution prepared by dissolving 9.2 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water was added, the temperature was adjusted to 75 ° C., and then 70.1 g of styrene, n -A monomer mixture composed of 19.9 g of butyl acrylate and 10.9 g of methacrylic acid was added dropwise over 1 hour, and this system was heated and stirred at 75 ° C for 2 hours, thereby causing a polymerization reaction (first-stage polymerization). Reaction), a dispersion of resin particles made of a high molecular weight resin (hereinafter also referred to as “latex (1H)”) was prepared.

  (2) Formation of intermediate layer (second stage polymerization): 98.0 g of tetraerythritol tetrabehenate (hereinafter referred to as “release agent (1)”) was added to styrene 105 in a flask equipped with a stirrer. .6 g, n-butyl acrylate 30.0 g, methacrylic acid 6.2 g and n-octyl-3-mercaptopropionic acid ester 5.6 g added to a monomer mixture, heated to 90 ° C. and dissolved. A monomer solution was prepared. On the other hand, a surfactant solution (aqueous medium) in which 1.6 g of anionic surfactant (1) was dissolved in 2700 ml of ion-exchanged water was charged into a flask equipped with a stirrer, and the internal temperature was raised to 98 ° C. The latex (1H) obtained by the first stage polymerization was added in an amount of 28 g in terms of solid content.

  Next, the monomer solution was added to the surfactant solution containing the latex (1H) by a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. An emulsified liquid in which emulsified particles (oil droplets) having a uniform dispersed particle size (284 nm) were dispersed was prepared by mixing and dispersing over time. Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion exchange water and 750 ml of ion exchange water are added to this dispersion (emulsion). A polymerization reaction (reaction related to the second stage polymerization) is performed by heating and stirring for 12 hours, and the surface of the resin particles made of a high molecular weight resin is coated with an intermediate molecular weight resin containing the release agent (1). A dispersion of composite resin particles having a structure (hereinafter also referred to as “latex (1HM)”) was prepared. When the obtained latex (1HM) was dried and the particles constituting the latex (1HM) were observed with a scanning electron microscope, the release agent (1) was the main component in addition to the composite resin particles. Particles (particle diameter 400 to 1000 nm) were confirmed.

  (3) Formation of outer layer (third stage polymerization): 7.4 g of polymerization initiator (KPS) was ionized in a flask equipped with a stirrer charged with the entire amount of latex (1HM) obtained by second stage polymerization. An initiator solution dissolved in 200 ml of exchange water was added and the temperature was kept at 80 ° C., and 300 g of styrene, 95 g of butyl acrylate, 15.3 g of methacrylic acid and 10.4 g of n-octyl-3-mercaptopropionic acid ester A monomer mixture consisting of the above was added dropwise over 1 hour, and this system was heated and stirred at 80 ° C. for 2 hours to carry out a polymerization reaction (reaction according to the third stage polymerization). By cooling to 0 ° C., the surface of the resin particles made of high molecular weight resin is coated with the intermediate molecular weight resin, and the intermediate layer made of the intermediate molecular weight resin is further coated. Dispersion latex of the composite resin particles having a structure surface is covered by a low molecular weight resin (hereinafter, also referred to as "Latex (1HML)".) Was prepared. The composite resin particles constituting the obtained latex (1HML) have a weight average particle diameter of 122 nm, and the binder resins constituting the composite resin particles are 138,000, 80,000 and 13, 000 and three peak molecular weights were confirmed.

[Preparation Example 1 of Shell Agent]
An initiator solution prepared by dissolving 14.8 g of a polymerization initiator (KPS) in 400 ml of ion-exchanged water was charged into a flask equipped with a stirrer, and 600 g of styrene, 190 g of butyl acrylate, methacrylic acid were maintained at a temperature of 80 ° C. A monomer mixture composed of 30.0 g of acid and 20.8 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour, and this system was heated and stirred at 80 ° C. for 2 hours for polymerization reaction. Thereafter, the system was cooled to 27 ° C. to prepare a dispersion of resin particles made of a low molecular weight resin (hereinafter also referred to as “latex (2L)”). The resin particles constituting the obtained latex (2L) have a weight average particle diameter of 128 nm, and the binder resin constituting the resin particles has a peak molecular weight of 11,000. It was.

[Preparation Example 1 of Colorant Dispersion]
59.0 g of sodium n-dodecyl sulfate was dissolved in 1600 ml of ion-exchanged water with stirring. While stirring this solution, 420.0 g of carbon black “Regal 330R” (manufactured by Cabot) was gradually added, and then dispersed using a mechanical disperser “Claremix” (manufactured by M Technique Co., Ltd.). By processing, a dispersion of colorant particles (hereinafter referred to as “colorant dispersion (1)”) was prepared. When the particle diameter of the colorant particles in the obtained colorant dispersion (1) was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the weight average particle diameter was 110 nm. there were.

[Production Example 1 of Toner Particles]
In a reaction vessel (four-necked flask) equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device, 420.7 g of latex (1HML) (solid content conversion), 900 g of ion-exchanged water, and a colorant dispersion ( 1) 200 g was charged and the internal temperature was adjusted to 25 ° C., and then 5N sodium hydroxide aqueous solution was added to the dispersion mixed solution to adjust the pH to 10. Next, an aqueous solution in which 18.9 g of polyethyleneimine (Epomin SP-006; manufactured by Nippon Shokubai Co., Ltd.) as a flocculant was dissolved in 359 g of ion-exchanged water was added at 25 ° C. over 5 minutes with stirring. After standing for 3 minutes, heating was started, and the system was heated to 80 ° C. over 60 minutes. The amount of the flocculant added was 4.4% by weight with respect to the resin particles.

  In this state, the particle size of the associated particles was measured with Coulter Multisizer 3 (manufactured by Beckman Coulter). When the median diameter D50 on the volume basis reached 6.1 μm, 40.2 g of sodium chloride was added to 1000 ml of ion-exchanged water. An aqueous solution dissolved in the solution was added to stop the particle growth, and further, the mixture was heated and stirred at a liquid temperature of 98 ° C. for 6 hours to continue the ripening treatment.

  To this system, 96 g of latex (2 L) (in terms of solid content) is added, and the mixture is heated and stirred at a liquid temperature of 98 ° C. for 3 hours, thereby forming latex (2 L) on the surface of the produced associated particles. After fusing the resin particles, 40.2 g of sodium chloride was added, and further cooled to 30 ° C. under conditions of 8 ° C./min, hydrochloric acid was added to adjust the pH to 2.0, and stirring was stopped. . The produced associated particles were filtered, washed repeatedly with ion exchange water at 45 ° C., and then dried with hot air at 40 ° C. to obtain toner particles (hereinafter also referred to as “toner particles (1)”). The volume average particle size of the toner particles was 6.0 μm.

[Toner Production Example 1]
To the toner particles (1), hydrophobic silica (having a number average primary particle diameter of 12 nm and a hydrophobization degree of 68) is added at a ratio of 1% by weight, and hydrophobic titanium oxide (number average primary particle diameter is 1%). Toner having a hydrophobization degree of 20 nm at a ratio of 1.2% by weight was added and mixed with a Henschel mixer to obtain toner (1). The toner is obtained by adding hydrophobic silica and hydrophobic titanium oxide to the toner particles, and the particle size thereof is the same as that of the corresponding toner particles.
[Developer Production Example 1]
The toner (1) was mixed with a ferrite carrier coated with a silicone resin and having a volume-based average particle diameter of 60 μm to prepare “Developer 1” having a toner concentration of 6% by mass.

<Examples 2-3 and Reference Examples 1-2 / Comparative Examples 1-2>
A toner and a developer were produced in the same manner as in Example 1 except that the aggregating agent shown in Table 1 was used in a prescribed amount.

<Evaluation>
As an evaluation method, the water content was measured using the obtained toner, and the charge amount of the obtained developer was measured. For the image evaluation, a commercial multifunction device “bizhub Pro C500” (manufactured by Konica Minolta Business Technologies, Inc.) adopting an electrophotographic method was used to evaluate an image with a single color of black toner.

(Particle size distribution (CV value))
The particle size distribution was measured with a Coulter Multisizer 3 (manufactured by Beckman Coulter) to obtain a CV value.

(Moisture content environment dependency)
The amount of water _WH and the amount of water _WL were measured by the method described above, and the difference between them (W _H -W _L ) was determined. The difference in water content is an acceptable level of 0.5 or less.

(Charge amount environment dependency)
The toner was left for 24 hours in a high temperature and high humidity environment at a temperature of 33 ° C. and a relative humidity of 80% RH, and the charge amount _CH was measured. On the other hand, the toner was left for 24 hours in a low-temperature and low-humidity environment at a temperature of 10 ° C. and a relative humidity of 20% RH, and the charge amount _CL was measured. Their difference a _(C L -C _H) was determined.
As the difference in charge amount, 30 μC / g or less is an acceptable level.
The charge amount was measured according to the following method. The toner is placed under the condition that the developer to be measured is slid between the parallel plate (aluminum) electrodes, the gap between the electrodes is 0.5 mm, the DC bias is 1.0 KV, the AC bias is 4.0 KV, and 2.0 KHz. Then, the charge amount and mass of the developed toner were measured, and the charge amount per unit mass Q / m (μC / g) was defined as the charge amount.

(Fog)
In an environment of a temperature of 33 ° C. and a relative humidity of 80% RH, an original image of A4 size with a pixel rate of 10% (a character image, a human face photo, a solid white image, and a solid black image with a pixel rate of 7% are each 1 / 100,000 images were formed in a single intermittent mode. For the formed first (initial) and 100,000th (printed) images, absolute images at 20 arbitrary positions on a white background where no fixed image is printed by the Macbeth reflection densitometer “RD-918” The concentration was measured and the average value was calculated. The difference between the average value and the average value obtained by measuring the absolute image density at 20 arbitrary positions on the transfer paper before being subjected to the image forming process was determined as the fog density. If the fog density is 0.006 or less, it can be said that there is no practical problem. The case where the fog density was 0.003 or less was evaluated as “◯”, the case where it exceeded 0.003 and 0.006 or less was evaluated as “Δ”, and the case where it exceeded 0.006 was evaluated as “x”.

(Image density)
In a high temperature and high humidity environment with a temperature of 33 ° C. and a relative humidity of 80% RH and under a low temperature and low humidity environment with a temperature of 10 ° C. and a relative humidity of 20% RH, 100,000 original images were formed by the same method as the fog evaluation method. . The image density of the solid black portion in the first (initial) image and the 100,000th image (printing durability) image formed in each environment was measured with a Macbeth reflection densitometer “RD-918”. A case where the difference between the measured value relating to the image obtained in the high temperature and high humidity environment and the measured value relating to the image obtained in the low temperature and low humidity environment is less than 0.05, “◯”, 0.05 or more The case of less than 0.1 was evaluated as “Δ” (no problem in practical use), and the case of 0.1 or more was evaluated as “x”.

Claims (2)

A toner for developing electrostatic images obtained by aggregating and fusing at least resin particles in the presence of an aggregating agent in an aqueous medium, and using a polyethyleneimine having a number average molecular weight of 500 to 5000 as the aggregating agent. Toner for developing electrostatic images.   The electrostatic image developing toner according to claim 1, wherein the polyethyleneimine has a branched structure.