JP2012128142A - Production method of toner and toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of toner, which gives a toner excellent in productivity and excellent in heat-resistant storage property, low-temperature fixability and preventing property against toner scattering.SOLUTION: The production method aims to produce a core-shell toner having a core layer containing a first resin and a colorant and a shell layer on the core layer. The production method for the toner includes: a shell-forming step of mixing a dispersion liquid containing core particles that contain the first resin and the colorant with a shell resin dispersion liquid containing particles for the shell layer that contain a second resin having vinyltriaryl imidazole group and a third polyester resin, so as to coat the core particle with the particles for the shell layer to form a shell layer (A); and a crosslinking step of treating the layer (A) with an oxidizing agent solution containing an oxidizing agent to crosslink the second resin.

Description

  The present invention relates to a method for producing toner used in an image forming method using an electrophotographic image forming apparatus.

  In recent years, from the viewpoint of global warming prevention, energy saving has been studied in various fields, and efforts have been made to use low energy, such as power saving during standby, in information devices such as image forming apparatuses. On the other hand, studies have been made to lower the fixing temperature in the fixing process that consumes the most energy.

  In order to realize such a decrease in the fixing temperature, for example, Patent Document 1 discloses that a polymer containing a carboxylic acid component and a polyvalent metal compound are combined as toner used in an electrophotographic image forming apparatus. Toners containing crosslinked resins are disclosed.

  According to such a toner, since the melt viscosity of the resin is lowered by cleaving the bond related to the crosslinking by heat at the time of heat fixing, low temperature fixability can be obtained while heat resistant storage stability at the time of storage can be obtained.

  In general, a toner having a basic structure is originally formed of a resin having a high glass transition point in order to obtain heat-resistant storage property, but there is a problem that the fixing temperature must be high. That is, it is difficult to satisfy both the heat-resistant storage property and the low-temperature fixability because they are in a trade-off relationship.

  Even using such a resin as described above, the fixing temperature is required to be at least about 150 ° C., and there is a problem that sufficient low-temperature fixing property may not be obtained.

Japanese Patent Publication No. 8-3665

  An object of the present invention is to provide a toner production method that gives a toner that is excellent in productivity, excellent in heat-resistant storage and low-temperature fixability, and excellent in toner scattering prevention.

  The above-described problems of the present invention are solved by the following means.

  1. A toner production method for producing a core-shell type toner having a core layer containing a first resin and a colorant and having a shell layer on the core layer, the method comprising the first resin and the colorant A core resin dispersion containing core particles, a shell resin dispersion containing particles for a shell layer containing a second resin having a triarylimidazole group represented by the following general formula (1) and a third resin A shelling step of mixing the solution with the solution to form the shell layer A by covering the core particles with the particles for the shell layer, and treating the shell layer A with an oxidizing agent solution containing an oxidizing agent. A toner production method comprising a crosslinking step of crosslinking two resins.

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. ]
2. 2. The method for producing a toner according to 1 above, wherein the third resin is a polyester resin.

  3. The shell layer particles include a dissolution step of preparing the shell first resin solution by dissolving the third resin in an organic solvent, and a shell second resin containing the shell first resin solution and the second resin. A mixing step of preparing a solution, wherein the shell second resin solution is dispersed in an aqueous medium to prepare a shell second resin solution dispersion in which droplets of the shell second resin solution are dispersed in the aqueous medium. 3. The toner according to 2, wherein the toner is produced by a production method having a dispersion step and a solvent removal step of removing the organic solvent from the shell second resin solution dispersion to form resin particles. Production method.

  4). 4. The method for producing a toner according to 3 above, wherein the second resin contained in the shell second resin solution is a resin polymerized and synthesized in the shell first resin solution.

  5). 5. The method according to any one of 1 to 4, wherein the second resin is a resin obtained by polymerization using a polymerizable monomer represented by the following general formula (2). Toner manufacturing method.

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. R ⁴ represents a hydrogen atom or a methyl group. L represents a single bond or a divalent linking group. ]
6). 6. A toner produced by the method for producing a toner according to any one of 1 to 5, wherein the toner comprises a core layer containing the first resin and the colorant, and the general layer is formed on the core layer. A shell layer containing a polyester resin and a second resin having a triarylimidazole group represented by the formula (1) has a cross-linked structure represented by the following general formula (3). A toner comprising:

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. R ⁴ represents a hydrogen atom or a methyl group. L represents a single bond or a divalent linking group. ]

  By the above means of the present invention, there is provided a toner production method that provides a toner having excellent productivity, heat-resistant storage stability, at the same time, sufficient low-temperature fixability, high particle strength, and excellent toner scattering prevention properties. it can.

  The present invention relates to a toner production method for producing a core-shell type toner having a core layer containing a first resin and a colorant and having a shell layer on the core layer, the method comprising: A core resin dispersion containing core particles containing a colorant, a second resin having a triarylimidazole group represented by the following general formula (1), and a shell layer particle containing a third resin The shell resin dispersion is mixed to form a shell layer A by covering the core particles with the shell layer particles, and the shell layer A is treated with an oxidizing agent solution containing an oxidizing agent. And a cross-linking step of cross-linking the second resin.

  In the present invention, in particular, the second resin and the third resin having the triarylimidazole group are used for the shell layer, and after the shell layer is provided on the core layer, the second resin of the shell layer is oxidized. A toner manufacturing method that provides a toner having excellent productivity, heat-resistant storage stability, sufficient low-temperature fixability, high particle strength, and excellent toner scattering prevention property by crosslinking with an agent. Can be provided.

  The production method of the present invention includes a core resin dispersion containing core particles containing a first resin and the colorant, a second resin having a triarylimidazole group represented by the general formula (1), and A shell forming step of mixing a shell resin dispersion containing a shell resin particle containing a third resin and covering the core particles with a shell layer A containing the second resin and the third resin; The layer A is treated with an oxidant solution containing an oxidant and has a crosslinking step for crosslinking the second resin.

(Shelling process)
In the shelling step, the core resin dispersion containing the first resin and the core particles containing the colorant, the second resin having the triarylimidazole group represented by the general formula (1), and the third resin And a shell resin dispersion containing shell layer particles containing the above resin and covering the core layer with the shell layer A containing the second resin and the third resin.

  The core layer is composed of core particles containing a first resin and a colorant.

  The method for producing the core resin dispersion containing the core particles is not limited, but the first resin dispersion containing the first resin particles is produced and the colorant dispersion containing the colorant particles dispersedly. It is preferable from the viewpoint of productivity to prepare the core resin dispersion containing the core particles by mixing the dispersions and aggregating the first resin particles and the colorant particles.

  Other methods for producing a core resin dispersion containing core particles include, for example, suspension polymerization in which monomer droplets containing a colorant are polymerized to form a core particle dispersion, and a resin and a colorant in a solvent. Examples include a solvent desolubilization method in which dissolved or dispersed oil droplets are dispersed in water, and then the solvent in the oil droplets is removed to obtain a core particle dispersion.

  The shell layer A is formed by mixing a core resin dispersion containing core particles and a shell resin dispersion containing shell layer particles containing a second resin and a third resin.

  Hereinafter, the production of the first resin dispersion, the colorant dispersion, the shell resin dispersion, and the formation method of the shell layer A will be described.

(Preparation of first resin dispersion)
For example, if the first resin uses a radical polymerizable monomer such as styrene acryl, the step of preparing the first resin dispersion is radical initiation on the polymerizable monomer that should form the thermoplastic resin. Dissolve or disperse the agent and chain transfer agent, and if necessary, dissolve or disperse the toner particle constituent materials such as the release agent and charge control agent to prepare a polymerizable monomer solution, which is used as a surface active agent. A step of obtaining the first resin dispersion liquid by adding it into an aqueous medium using an agent, etc., and performing a polymerization reaction while mixing and stirring can be mentioned.

  Further, if the first resin is a resin such as polyester, the polyester resin is dissolved in a solvent such as ethyl acetate, and emulsified and dispersed in an aqueous medium using a surfactant. There is a step of performing a solvent removal treatment to obtain a first resin dispersion.

  However, it is not restricted to these methods.

  The first resin particles in the dispersion prepared in these steps preferably have a volume-based median diameter in the range of 50 to 500 nm. More preferably, it is 80-300 nm.

  Here, the “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent.

  Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and alcohol-based organic solvents that do not dissolve the resulting resin are preferable.

  Examples of the first resin include thermoplastic resins such as polyester resins, styrene resins, (meth) acrylic resins, vinyl polymers such as styrene acrylic resins, olefin resins, polyamide resins, polycarbonate resins, and polyresins. Examples include ether resins, polyvinyl acetate resins, polysulfone resins, polyurethane resins, and the like. Preference is given to polyester resins and styrene acrylic resins.

  The polyester resin can be synthesized by polycondensation of a polyhydric alcohol and a polyvalent carboxylic acid.

  As the polyhydric alcohol, if it is non-radically polymerizable, for example, 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-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1, Aliphatic diols such as 14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol; bisphenols such as bisphenol A and bisphenol F; and bisphenols such as these ethylene oxide adducts and propylene oxide adducts Of alkylene oxide adducts It can be mentioned, and as the trivalent or higher-valent alcohols include glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like.

  Further, those having radical polymerizability include, for example, 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol, 9-octadecene-7,12. -Those having a radically polymerizable unsaturated double bond such as diol; those having a radically polymerizable unsaturated triple bond such as 2-butyne-1,4-diol, 3-butyne-1,4-diol, etc. be able to. These can be used individually by 1 type or in combination of 2 or more types.

  Examples of the polyvalent carboxylic acid include non-radical polymerizable ones such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonane. Dicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid Acids, aliphatic dicarboxylic acids such as 1,18-octadecanedicarboxylic acid; lower alkyl esters and acid anhydrides thereof; phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid Acids, aromatic dicarboxylic acids such as 4,4'-biphenyldicarboxylic acid; Lit acids, such as trihydric or higher polycarboxylic acids such as pyromellitic acid.

  In addition, unsaturated fatty acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenyl succinic acid, n-dodecenyl succinic acid, n-octenyl succinic acid, etc., as long as they have radical polymerizability Dicarboxylic acids; and acid anhydrides or acid chlorides thereof; maleic acid, fumaric acid and itaconic acid are preferably used because they exhibit particularly excellent radical polymerizability. These can be used individually by 1 type or in combination of 2 or more types.

  As a vinyl polymer such as styrene acrylic resin, radically polymerizable monomers for obtaining this are styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn -Styrene or styrene derivatives such as dodecyl styrene; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Stearyl methacrylate, Methacrylic acid ester derivatives such as lauryl tacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylic acid ester derivatives such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; olefins such as ethylene, propylene, and isobutylene; vinyl fluoride, vinylidene fluoride Vinyl fluorides such as vinyl propionate, vinyl acetate, vinyl benzoate, and other vinyl esters; vinyl methyl ether, vinyl ethyl ether, and other vinyl ethers; Vinyl ketones such as til ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; Vinyl compounds such as vinyl naphthalene and vinyl pyridine; acrylonitrile, methacrylate Examples thereof include vinyl monomers such as acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide. These vinyl monomers can be used alone or in combination of two or more.

  Moreover, it is preferable to use what has an ionic dissociation group as a radically polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate Etc.

  In order to stably disperse the particles in the aqueous medium, a surfactant may be added to the aqueous medium. Examples of such a surfactant include various conventionally known anionic surfactants and cationic systems. Surfactants, nonionic surfactants, and the like can be used. This also applies to the subsequent preparation of the dispersion.

  Examples of the anionic surfactant include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate salts such as sodium lauryl sulfate; polyethoxyethylene lauryl ether sodium sulfate Polyoxyethylene alkyl ether sulfate salts of polyoxyethylene alkylaryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate, etc. Examples thereof include alkyl sulfosuccinic acid ester salts and derivatives thereof.

  Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.

  Furthermore, examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether, and sorbitan mono Sorbitan higher fatty acid esters such as laurate, sorbitan monostearate, sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaurate, polyoxyethylene monostearate Polyoxyethylene higher fatty acid esters such as glycerin higher fatty acid esters such as oleic acid monoglyceride and stearic acid monoglyceride Ethers; polyoxyethylene - polyoxypropylene - and the like block copolymer.

  The polymerization initiator is a water-soluble polymerization initiator having a 10-hour half-life temperature of less than 10-hour half-life temperature (A), preferably less than (A-10 ° C.) according to the radical generator used. As long as there is something, an appropriate thing can be used.

  Specific examples of the polymerization initiator include persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2- Amidinopropane) salts), organic peroxides and the like.

  Generally used chain transfer agents can be used for the purpose of adjusting the molecular weight of the thermoplastic resin.

  The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan, and styrene dimers.

  After mixing the first resin dispersion obtained as described above and the colorant dispersion described below, the pH of the mixture can be adjusted and aggregated to form core particles. At this time, it is effective to use a flocculant.

  As the flocculant to be used, a surfactant having a reverse polarity to the surfactant used for the dispersant, an inorganic metal salt, and a metal complex having a valence of 2 or more can be preferably used. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

  Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers.

(Preparation of colorant dispersion)
As a process for preparing a colorant dispersion, a colorant particle dispersion is prepared by adding a colorant to an aqueous medium and applying mechanical energy thereto to disperse the colorant particles in the aqueous medium. Is done.

  The disperser for dispersing oil droplets by mechanical energy is not particularly limited, and a stirring device “CLEAMIX” (manufactured by M Technique Co., Ltd.) equipped with a rotor that rotates at high speed, an ultrasonic disperser, Examples thereof include a mechanical homogenizer, a manton gourin, and a pressure homogenizer.

  The colorant particles in the dispersion prepared in the colorant dispersion preparation step preferably have a volume-based median diameter in the range of 20 to 1,000 nm, more preferably 20 to 140 nm, and particularly preferably 30. ~ 100 nm.

  The method for controlling the volume-based median diameter of the colorant particles to 20 to 1,000 nm can be controlled, for example, by adjusting the magnitude of the mechanical energy described above.

  As the colorant, various organic or inorganic pigments as exemplified below can be used.

  That is, as the colorant for black toner, carbon black, magnetic material, iron / titanium composite oxide black and the like can be used, and as carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, etc. Can be used. Moreover, ferrite, magnetite, etc. can be used as the magnetic material.

  Examples of yellow colorants for yellow toner include C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, etc., and C.I. I. Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, etc. can be used, and mixtures thereof can also be used.

  As a magenta colorant for magenta toner, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, etc. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, etc. can be used. Mixtures can also be used.

  As a cyan colorant for cyan toner, C.I. I. Solvent Blue 25, C.I. I. Solvent Blue 36, C.I. I. Solvent Blue 60, C.I. I. Solvent Blue 70, C.I. I. Solvent Blue 93, C.I. I. Solvent Blue 95 and the like, C.I. I. Pigment Blue 1, 7, 15, 60, 62, 66, 76, etc. can be used.

  These pigments can be used alone or in combination of two or more.

  The content ratio of the colorant is preferably 0.5 to 20% by mass in the toner particles, and more preferably 2 to 10% by mass.

(Preparation of shell resin dispersion)
The shell resin dispersion is a dispersion containing dispersed particles for a shell layer containing a second resin having a triarylimidazole group represented by the following general formula (1) and a third resin. .

(Second resin having a triarylimidazole group represented by the general formula (1))
In general formula (1), R ¹ is a hydrogen atom or a chlorine atom, preferably a hydrogen atom.

In the general formula (1), when R ¹ is a chlorine atom, the group R ¹ is preferably bonded to the para position with respect to the imidazole ring.

When the group R ¹ consisting of a chlorine atom is bonded to the para position with respect to the imidazole ring, it is easy to form a cross-linking bond between the imidazole rings described later.

In the general formula (1), R ² and R ³ are a hydrogen atom, a chlorine atom or a methoxy group, preferably a hydrogen atom.

When R ² and R ³ in the triarylimidazole group represented by the general formula (1) are chlorine atoms, R ² and R ³ are in any of the ortho, meta, and para positions with respect to the imidazole ring. It may be combined.

When R ² and R ³ are methoxy groups, it is preferable that R ² and R ³ are bonded to the ortho position with respect to the imidazole ring.

R ² and R ³ are preferably the same from the viewpoint of productivity.

  The second resin having a triarylimidazole group represented by the general formula (1) can be obtained by a polymerization reaction using a polymerizable monomer having a triarylimidazole group represented by the general formula (1). it can.

  The polymerization reaction may be performed using only the monomer, or may be performed together with other comonomer.

  The polymerizable monomer can be used without particular limitation as long as it is a monomer used for radical polymerization, condensation polymerization, and the like, but the polymerizable monomer represented by the general formula (2) is used. It is preferable.

In General formula (2), L represents a single bond or a bivalent coupling group. R ^{1 to R 3,} from the ^{R 1} and ^{R 3} in the general formula (1) are each synonymous. That is, one of the groups bonded to L in the general formula (2) is a group represented by the general formula (1).

R ⁴ represents a hydrogen atom or a methyl group.

  In the general formula (2), the imidazole ring in the triarylimidazole group is bonded to the meta position with respect to the group L with respect to the benzene ring to be bonded continuously to the group L in the triarylimidazole group. Is preferred.

  The polymerizable triarylimidazole compound in which the imidazole ring is bonded to the meta position relative to the group L with respect to the benzene ring to be bonded continuously to the group L in the triarylimidazole group has a crosslinking bond between the imidazole rings. Easy to form.

  Examples of the divalent linking group represented by L include —C (═O) —NH—, —C (═O) O—, —NH (C═O) NH— and —NH—C (═O ) O- and the like.

  As a polymerizable monomer represented by General formula (2), the compound represented by the following exemplary compounds 1-8 can be illustrated, for example.

  The second resin according to the present invention can be obtained by a polymerization reaction using the polymerizable monomer as described above, and is a copolymerizable monomer copolymerizable with the polymerizable monomer. Those copolymerized are preferably used.

  Examples of the monomer for copolymerization include the aforementioned (meth) acrylic acid, (meth) acrylic acid ester, and styrene.

  The copolymerization ratio of the polymerizable monomer (polymerizable triarylimidazole compound) and the monomer for copolymerization is 1:99 to 30: in a molar ratio of polymerizable triarylimidazole compound: monomer for copolymerization. 70 is preferable.

  In the present invention, the second resin and the third resin are used for forming the shell layer. In order to form the shell layer, the shell layer containing the second resin and the third resin as will be described later. A shell resin dispersion containing dispersed particles is used.

(Third resin)
The third resin according to the present invention is not particularly limited as long as it is a resin other than the second resin, but the third resin includes a polyester resin, a styrene resin, a (meth) acrylic resin, and a styrene acrylic resin. And vinyl polymers such as olefin resins, polyamide resins, polycarbonate resins, polyether resins, polyvinyl acetate resins, polysulfone resins, polyurethane resins and the like. Of these, a polyester resin is particularly preferably used as the third resin.

(Polyester resin)
The polyester resin used in the present invention can be produced by a polycondensation reaction using a polyester-forming composition comprising a polyhydric alcohol (derivative) and a polyvalent carboxylic acid (derivative) as raw materials.

  Examples of polyhydric alcohol derivatives include polyhydric alcohol ester compounds and hydroxycarboxylic acids, and examples of polyhydric carboxylic acid derivatives include alkyl esters, acid anhydrides, and acid chlorides of polyhydric carboxylic acids.

  A polyhydric alcohol is a compound containing two or more hydroxyl groups in one molecule. Among these, a divalent polyol (diol) is a compound containing two hydroxyl groups in one molecule. For example, ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, Examples include dodecanediol, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct. Examples of polyols other than divalent polyols include glycerin, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine, and tetraethylol benzoguanamine.

  The polyvalent carboxylic acid is a compound containing two or more carboxyl groups in one molecule. Among these, divalent carboxylic acid is a compound containing two carboxyl groups in one molecule. For example, oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, Nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephrine Tar acid, malonic acid, pimelic acid, tartaric acid, mucoic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenedi Glycolic acid, p-phenylene diglycolic acid, o-phenylene di Recolic acid, diphenylacetic acid, diphenyl-p, p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, dodecenyl succinic acid, etc. Can be mentioned.

  Examples of the polyvalent carboxylic acid other than the divalent carboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

  The polyester structure can be arbitrarily controlled by a combination of these polycondensable monomers, such as an amorphous resin structure, a crystalline resin structure, or a mixed structure thereof. In the present invention, one or two polyester resins can be used. More than one kind of polyester can be used, and a combination of polyester structures such as non-crystalline and crystalline can be arbitrarily selected.

  For example, in order to obtain a crystalline polyester structure, the polyhydric alcohol component used is ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butane. Diol, 1,4, butenediol, neopentyl glycol, 1,5-pentane glycol, 1,6-hexane glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene A glycol etc. can be mentioned. Examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutamic acid, Examples thereof include n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, acid anhydrides or acid chlorides thereof.

  As the polyol used for obtaining the non-crystalline polyester, among the above polyols, in particular, polytetramethylene glycol, bisphenol A, bisphenol Z, hydrogenated bisphenol A, cyclohexanedimethanol, alkylene oxide adducts thereof, etc. Is preferably used. Examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the polyvalent carboxylic acid used to obtain the non-crystalline polyester, among the above polyvalent carboxylic acids, dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid. Acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p, p'-dicarboxylic acid, naphthalene- Examples include 1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, and cyclohexanedicarboxylic acid. Examples of the polyvalent carboxylic acid other than dicarboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid. Moreover, you may use what derived the carboxyl group of these carboxylic acid into the acid anhydride, the acid chloride, or ester. Among these, it is preferable to use terephthalic acid or its lower ester, diphenylacetic acid, cyclohexanedicarboxylic acid, or the like. The lower ester refers to an ester of an aliphatic alcohol having 1 to 8 carbon atoms.

  As the polyvalent carboxylic acid capable of introducing an ethylenically unsaturated bond, maleic acid, fumaric acid and itaconic acid can be preferably used.

  As the polyester resin, the crystalline melting point Tm in the case of crystallinity is preferably 50 ° C. or higher and 120 ° C. or lower, more preferably 55 ° C. or higher and 90 ° C. or lower.

  A Tm of 50 ° C. or higher is preferable because the cohesive strength of the crystalline resin in the high temperature range is in an appropriate range, and good releasability can be obtained during fixing, and no offset is generated. . Further, it is preferable that Tm is 120 ° C. or lower because sufficient melting can be obtained and a suitable minimum fixing temperature can be obtained.

  On the other hand, when the polyester resin particles are amorphous, the glass transition point Tg is preferably 30 ° C. or higher and 80 ° C. or lower, more preferably 50 ° C. or higher and 65 ° C. or lower. A Tg of 30 ° C. or higher is preferred because the cohesive strength of the resin itself in the high temperature region is appropriate and hot offset does not occur during fixing. Moreover, it is preferable that Tg is 80 ° C. or lower because sufficient melting can be obtained and a suitable minimum fixing temperature can be obtained.

  Here, for the measurement of the melting point of the crystalline resin and the glass transition point of the amorphous resin, a differential scanning calorimeter “DSC-7” (manufactured by PerkinElmer) and a thermal analyzer controller “TAC7 / DX” (PerkinElmer) ). Specifically, 4.50 mg of resin is sealed in an aluminum pan “KITNO.0219-0041”, which is set in a sample holder of “DSC-7”, and an empty aluminum pan is used for reference measurement. Heat-cool-Heat temperature control was performed at a measurement temperature of 0 to 200 ° C. under measurement conditions of a temperature increase rate of 10 ° C./min and a temperature decrease rate of 10 ° C./min. Data on heat is acquired, and the crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point. For non-crystalline resins, the 2nd. Data on Heat is acquired, and the glass transition point is the intersection of the baseline extension before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rise of the first endothermic peak and the peak apex. As shown. 1st. The heat was raised at 200 ° C. for 5 minutes.

  The “crystallinity” as shown in the above “crystalline polyester resin” means that, in differential scanning calorimetry (DSC), it has a clear endothermic peak rather than a stepwise endothermic change. Means that the half-value width of the endothermic peak when measured at a heating rate of 10 ° C./min is less than 10 ° C.

  On the other hand, a resin having a half-value width of an endothermic peak of 10 ° C. or more, or a resin in which no clear endothermic peak is observed means non-crystalline (amorphous).

  Moreover, it is preferable that the average molecular weight of the polyester resin to be used is 1,500 or more and 60,000 or less, More preferably, it is the range of 3,000 or more and 40,000 or less.

  When the average molecular weight is 1,500 or more, a cohesive force suitable as a binder resin is obtained, and the hot offset property is favorable, which is preferable. Further, it is preferable that the average molecular weight is 60,000 or less because good hot offset property and a suitable minimum fixing temperature can be obtained.

  The average molecular weight of the polyester resin used here is a peak molecular weight measured by gel permeation chromatography (GPC), and is measured by the following method. The peak molecular weight is a molecular weight corresponding to the elution time of the peak top in the molecular weight distribution, and when there are a plurality of molecular weight peaks, the molecular weight corresponds to the elution time of the peak top having the largest peak area ratio. Specifically, the molecular weight was measured using an apparatus “HLC-8220” (manufactured by Tosoh Corp.) and a column “TSKguardcolumn + TSKgelSuperHZM-M3” (manufactured by Tosoh Corp.), while maintaining the column temperature at 40 ° C. and tetrahydrofuran (THF) as a carrier solvent. Is flowed at a flow rate of 0.2 ml / min, and the measurement sample is dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which treatment is performed for 5 minutes using an ultrasonic disperser at room temperature. A sample solution is obtained by processing with a membrane filter, 10 μl of this sample solution is injected into the apparatus together with the carrier solvent, detected using a refractive index detector (RI detector), and from the molecular weight distribution of the measurement sample, It is to be measured.

  In addition, the polycondensable monomer may have partial branching or crosslinking depending on selection of the carboxylic acid valence and alcohol valence.

  Moreover, the polyester resin which added the acrylic resin by graft polymerization can also be used.

(Preparation of shell layer particles (preparation of shell resin dispersion))
A dispersion containing dispersed particles for the shell layer containing the second resin having the triarylimidazole group represented by the general formula (1) and the third resin is the second resin and the third resin. It is obtained by removing the solvent from the solution containing the solvent.

  The following methods are preferably used as a method for forming the shell layer particles by forming the shell layer particles.

  That is, a dissolving step of preparing a shell first resin solution by dissolving a third resin in an organic solvent, a mixing step of preparing a shell second resin solution containing the shell first resin solution and the second resin, Dispersing the shell second resin solution in an aqueous medium to prepare a shell second resin solution dispersion in which droplets of the shell second resin solution are dispersed in the aqueous medium, and the shell second resin solution dispersion A production method having a solvent removal step of removing the organic solvent from the liquid to form resin particles for the shell layer is preferably used.

(Dissolution process)
As an organic solvent used in the dissolution step, although it depends on the type of the third resin, it is necessary that the third resin and the second resin described later be dissolved, and further in the aqueous medium as described later. It must be incompatible with water so as to be dispersed to form oil droplets. Examples include aliphatic hydrocarbons such as hexane and peptane, aromatic hydrocarbons such as benzene, toluene, and xylene, and ester solvents such as methyl formate, ethyl formate, methyl acetate, ethyl acetate, and butyl acetate. It is done.

  Among these, for example, when the third resin is polyester, ethyl acetate or the like is preferably used.

  The range of the concentration of the shell first resin solution in the dissolving step is not limited as long as the shell second resin solution described later does not exhibit extremely high viscosity, but it is generally preferably 5% by mass to 30% by mass.

(Mixing process)
In the mixing step, a shell second resin solution containing a third resin-containing shell first resin solution and a second resin is prepared. The following two methods are used to prepare the shell second resin solution. There is a way.

  There are a method of synthesizing the second resin in the shell first resin solution and a method of synthesizing the second resin in advance and mixing it with the shell first resin solution.

  In the present invention, the former method, that is, the production method in which the second resin contained in the shell second resin solution is a resin synthesized by polymerization in the shell first resin solution is preferably applicable.

  As a method for synthesizing (polymerizing) the second resin in the shell first resin solution, a polymerizable monomer for forming the second resin in the shell first resin solution, a polymerization initiator, and, if necessary, the above-mentioned A method of adding a monomer for copolymerization and heating is preferably applied.

  Further, the second resin and the third resin may be in the form of a graft copolymer or a block copolymer by chemical bonding with each other, or may be in an independent form without chemical bonding with each other.

  A method of making a graft copolymer or a block copolymer into a form of a graft copolymer or a block copolymer by chemically bonding a styrene acrylic resin containing a triarylimidazole group as a second resin and a polyester resin as a third resin is a polymerizable triarylimidazole in the presence of a polyester resin. It is preferable to obtain a polymer by copolymerizing with a copolymerizable monomer that is copolymerizable with the compound.

  Specifically, the radically polymerizable 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1, polyhydric alcohol and polyvalent carboxylic acid used as raw materials for the polyester resin Polyhydric alcohols such as 8-diol, 9-octadecene-7,12-diol and radical polymerizable maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenyl succinic acid, n-dodecenyl succinic acid, By using unsaturated aliphatic dicarboxylic acids such as n-octenyl succinic acid; and anhydrides or acid chlorides thereof; unsaturated aromatic polyvalent carboxylic acids such as caffeic acid; Double bonds can be introduced. Thereafter, a chemical bond can be formed between the two resins by copolymerization with a copolymerizable monomer copolymerizable with the polymerizable triarylimidazole compound.

  Further, after adding a polymerizable monomer such as a vinyl compound having a functional group capable of reacting with a hydroxyl group derived from a polyhydric alcohol having a polyester terminal and a carboxylic acid derived from a polyvalent carboxylic acid, A chemical bond can be formed between both resins by copolymerizing with a copolymerizable monomer that can be copolymerized with the polymerizable triarylimidazole compound.

  Specifically, radical polymerization represented by acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, etc., for the hydroxyl group at the end of the polyester resin An isocyanate group-containing vinyl group compound represented by a reactive carboxylic acid, 2-isocyanatoethyl methacrylate, dimethylmeta-isopropenylbenzyl isocyanate, methacryloyl isocyanate, 2-isocyanatoethyl acrylate, etc. For 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 1-hydro Hydroxy group-containing vinyl compounds typified by sibutyl acrylate, 4-hydroxybutyl acrylate, glycidyl acrylate, glycidyl methacrylate, glycidyl α-ethyl acrylate, glycidyl α-n-propyl acrylate, glycidyl α-n-butyl acrylate , Acrylic acid-β-methylglycidyl, methacrylic acid-β-methylglycidyl, acrylic acid-β-ethylglycidyl, methacrylic acid-β-ethylglycidyl, acrylic acid-3,4-epoxybutyl, methacrylic acid-3,4- Epoxybutyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl, α-ethylacrylic acid-6,7-epoxyheptyl, o-vinylbenzylglycidyl ether, and m-vinylbenzylglycidylether And p-bi Adding a glycidyl group-containing vinyl compounds typified Le benzyl glycidyl ether, it is possible to introduce a double bond of the radical polymerizable at the end of the polyester resin.

  Thereafter, a chemical bond can be formed between the two resins by copolymerization with a copolymerizable monomer copolymerizable with the polymerizable triarylimidazole compound. The addition of the polymerizable monomer having a functional group capable of reacting with the polyester resin end group may be performed simultaneously with the polycondensation reaction of the polyester resin, or may be any addition reaction by addition after completion of the polycondensation reaction. May be.

  Furthermore, as a raw material for the polyester resin, a trihydric or higher polyhydric alcohol such as glycerin, trimethylolpropane, pentaerythritol, sorbitol or a trihydric or higher polyvalent carboxylic acid such as trimellitic acid or pyromellitic acid may be used in combination. After the addition of a polymerizable monomer such as a vinyl compound having a functional group capable of reacting with the hydroxyl group or carboxylic acid as described above, a polyester resin containing a hydroxyl group or carboxylic acid in the molecule can be obtained. A chemical bond can be formed between both resins by copolymerizing with a copolymerizable monomer copolymerizable with the polymerizable triarylimidazole compound.

  Thereafter, a chemical bond can be formed between the two resins by copolymerization with a copolymerizable monomer copolymerizable with the polymerizable triarylimidazole compound. The addition of the polymerizable monomer having a functional group capable of reacting with the polyester resin end group may be performed simultaneously with the polycondensation reaction of the polyester resin, or may be any addition reaction by addition after completion of the polycondensation reaction. May be.

  If a radically polymerizable monomer such as styrene / acrylic compound containing a triarylimidazole compound is used, a polymerization initiator or a chain transfer agent is dissolved or dispersed in the polymerizable monomer, and polymerization is performed as necessary. A polymerizable monomer solution is prepared by dissolving or dispersing a resin particle constituent material such as a resin other than the polymer obtained by copolymerization with a copolymerizable monomer copolymerizable with the polymerizable triarylimidazole compound.

  The copolymerization ratio between the polymerizable triarylimidazole compound and the monomer for copolymerization is preferably 1% to 50% in terms of the molar fraction of the polymerizable triarylimidazole compound.

  Any polymerization initiator can be used as long as its 10-hour half-life temperature is less than 10-hour half-life temperature (t), preferably less than (t-10 ° C.), according to the radical generator used. Can be used. Specific examples of the water-soluble polymerization initiator include persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis). (2-amidinopropane) salts), organic peroxides and the like. Specific examples of the oil-soluble polymerization initiator include azo compounds (azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethyl). Valeronitrile)), and organic peroxides. Preferably, among these, for example, when ethyl acetate or the like is used as a solvent, an azo compound (azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2, 2'-azobis (2,4-dimethylvaleronitrile).

  As the chain transfer agent, a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight. The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as 2-chloroethanol, octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan, and styrene dimers.

(Dispersion process)
In the dispersion step, a shell second resin solution dispersion in which droplets of the shell second resin solution are dispersed in an aqueous medium is prepared.

  The shell second resin solution dispersion is obtained by adding the shell second resin solution to an aqueous medium and subjecting it to a dispersion treatment.

  As used herein, “aqueous medium” refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran, and an alcohol-based organic solvent that does not dissolve the obtained shell second resin is preferable.

  The aqueous medium preferably contains a surfactant in advance for the subsequent steps. Examples of the surfactant that can be used include various conventionally known anionic surfactants, cationic surfactants, nonionic surfactants, and the like, and the same applies to the preparation of the subsequent dispersions. . In particular, as an anionic surfactant, for example, higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate salts such as sodium lauryl sulfate; polyethoxyethylene lauryl ether sodium sulfate Polyoxyethylene alkyl ether sulfate salts of polyoxyethylene alkylaryl ether sulfate salts such as sodium polyoxyethylene nonylphenyl ether sulfate; sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium polyoxyethylene lauryl sulfosuccinate, etc. Alkylsulfosuccinic acid ester salts and derivatives thereof are preferably used.

  After the shell second resin solution dispersion is added to the aqueous medium, mechanical stirring energy is applied using a disperser to form oil droplets. However, it is not limited to these methods.

(Desolvation process)
The solvent removal step is a step of removing the solvent dissolving the shell second resin from the shell second resin solution dispersion in which the droplets of the shell second resin solution are dispersed in the aqueous medium.

  A resin particle dispersion containing a triarylimidazole compound can be obtained by removing the solvent by a method such as decompression or heating.

  The resin fine particles in the dispersion prepared in these steps preferably have a volume-based median diameter in the range of 20 to 300 nm.

  As the resin particle dispersion containing a triarylimidazole compound, a resin portion composed of a polymerizable triarylimidazole compound and a monomer for copolymerization and other resin portions such as polyester are outer layers in the resin particle dispersion particles. / It is preferable to exhibit an inner layer portion and phase separation, and it is preferable that a resin having a triarylimidazole compound disposed in the outer layer portion is present.

(Method for forming shell layer A)
The shell layer A is obtained by mixing the core resin dispersion and the shell resin dispersion, and a core-shell type toner can be prepared. After mixing, the flocculant is added and the pH is adjusted. The shell layer particles containing the second resin are preferably attached so as to cover the surface of the core particles.

  For example, a flocculant is added to the core resin dispersion of the core particles, a shell resin dispersion containing the second resin is added, pH adjustment and temperature adjustment are performed, and the second resin is contained on the surface of the core particles. The particles to be agglomerated and fused together, and the surface of the core particles can be covered with the particles for the shell layer containing the second resin and the third resin.

  The volume-based median diameter of the shell layer particles is preferably 20 nm or more and 300 nm or less, and more preferably 30 nm or more and 250 nm or less.

  By setting the volume-based median diameter within the above range, the shell layer can be formed uniformly, which is preferable.

  As the flocculant to be used, a divalent or higher valent metal complex can be suitably used in addition to a surfactant and an inorganic metal salt. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

  The shell layer A according to the present invention may contain a charge control agent, and the charge control agent may be a substance that can give positive or negative charge by triboelectric charging and is colorless. There are no particular limitations, and various known positively chargeable charge control agents and negatively chargeable charge control agents can be used.

  The content ratio of the charge control agent in the toner is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  Examples of the positive charge control agent as the charge control agent include nigrosine dyes such as “Nigrosine Base EX” (manufactured by Orient Chemical Industries), “quaternary ammonium salt P-51” (manufactured by Orient Chemical Industries), “copy”. Quaternary ammonium salts such as “Charge PX VP435” (manufactured by Hoechst Japan), alkoxylated amines, alkylamides, molybdate chelate pigments, and imidazole compounds such as “PLZ1001” (manufactured by Shikoku Kasei Kogyo Co., Ltd.) Examples of the negative charge control agent include “Bontron S-22” (manufactured by Orient Chemical Industries), “Bontron S-34” (manufactured by Orient Chemical Industries), and “Bontron E-81” (Orient Chemical Industries, Ltd.). Manufactured by), "Bontron E-84" (manufactured by Orient Chemical Co., Ltd.), "Spiron Black T Metal complexes such as “H” (made by Hodogaya Chemical Co., Ltd.), thioindigo pigments, quaternary ammonium salts such as “Copy Charge NX VP434” (made by Hoechst Japan), “Bontron E-89” (Orient Chemical Industries) Calixarene compounds such as “LR147” (manufactured by Nippon Carlit Co., Ltd.), fluorine compounds such as magnesium fluoride and carbon fluoride, and the like. In addition to the metal complexes used as negative charge control agents, oxycarboxylic acid metal complexes, dicarboxylic acid metal complexes, amino acid metal complexes, diketone metal complexes, diamine metal complexes, azo group-containing benzene-benzene derivatives Those having various structures such as a skeletal metal body and an azo group-containing benzene-naphthalene derivative skeleton metal complex can be used.

  As described above, when the toner is configured to contain the charge control agent, the chargeability of the toner is improved.

  Further, a magnetic powder may be contained. As the magnetic powder, for example, magnetite, γ-hematite, various ferrites, or the like can be used.

  The content ratio of the magnetic powder is preferably 10 to 500% by mass in the toner particles, and more preferably 20 to 200% by mass.

  When a charge control agent and / or magnetic powder is contained, these are preferably contained in the shell layer A.

(Crosslinking process)
In the cross-linking step, the shell layer A obtained as described above is treated with an oxidizing agent solution containing an oxidizing agent to cross-link the second resin.

(Oxidant solution)
Examples of the oxidizing agent used in the oxidizing agent solution include ferricyanide salts such as potassium ferricyanide and sodium ferricyanide, hypochlorites such as sodium hypochlorite and potassium hypochlorite, potassium chlorite, Chlorates such as sodium chlorate, chlorates such as potassium chlorate, barium chlorate, calcium chlorate, sodium chlorate, ammonium chlorate, potassium perchlorate, sodium perchlorate, ammonium perchlorate, etc. Perchlorates, permanganates such as potassium permanganate, ammonium permanganate, sodium permanganate, bromates such as potassium bromate, sodium bromate, magnesium bromate, potassium dichromate, heavy Dichromates such as ammonium chromate, iodates, periodate Peroxides such as salts, boronates, perborates, percarbonates, peracetates, hydrogen peroxide, organic peroxides, nitrates such as nitrites, potassium nitrate, sodium nitrate, barium nitrate, ammonium nitrate And so on. Of these, sodium hypochlorite and potassium ferricyanide are particularly preferably used.

  The solvent for the oxidant solution is preferably water, but may contain an organic solvent such as water-soluble alcohols.

  The treatment of the shell layer A with an oxidant solution refers to a treatment in which the oxidant solution is brought into contact with the surface of the particles having the shell layer A obtained as described above.

  As a method of contacting, for example, a method of adding an oxidizing agent solution to a liquid containing core-shell type particles dispersed as described above, a dipping method of directly contacting the extracted particles, or the like can be applied.

  In the method of adding to the liquid, the treatment with the oxidant solution is performed by cooling the liquid containing the core-shell type particles having the layer A in a dispersed manner as described above, for example, at a cooling rate of −5 ° C./min. After that, it is preferable to carry out.

  The temperature of the oxidant solution is preferably 5 to 15 ° C., and the treatment time of the treatment with the oxidant solution is preferably 2 to 8 hours.

  In the cross-linking step, the second resin is cross-linked by the oxidizing agent to have the above cross-linked structure.

  Therefore, the surface of the shell layer containing the second resin of the toner produced by the production method of the present invention has the above-mentioned crosslinked structure, that is, only the surface of the shell layer has the above-mentioned crosslinked structure.

  From the above, it can be inferred that the reason why the toner produced by the production method of the present invention exhibits the effects of the present invention is as follows.

  That is, the toner produced by the production method of the present invention contains a specific cross-linked polymer, and the specific cross-linked polymer has a characteristic that a bond between imidazole rings is cleaved by application of pressure. It is. When this cleavage occurs, the molecular weight of the specific crosslinked polymer inevitably decreases.

  This molecular weight reduction due to cleavage also occurs due to the pressure applied by the fixing device, and the glass transition point and the melting characteristic curve of the toner shift to the low temperature side. Accordingly, the melting of the toner is accelerated even at a low heating temperature, and as a result, sufficient low-temperature fixability can be obtained.

  On the other hand, in the state before the pressure is applied, the specific cross-linked polymer has improved heat-resistant storage property because the micro Brownian motion due to heat is suppressed.

  Further, since the toner particles are reinforced by the crosslinking points, even if the fixing temperature is low, a large particle strength that is resistant to stress due to stirring or the like can be obtained.

  In particular, among these toners, the core-shell type is obtained by forming a dense shell and then cross-linking to obtain a specific cross-linked polymer. By containing the resin, the performance at the time of fixing is improved.

  As a result, the toner can be fixed at a low temperature while maintaining heat resistance as compared with a toner that is shelled with crosslinked particles, and the strength of the particles is further improved.

  The particle diameter of the particles that are the core-shell type toner after the crosslinking step is preferably 4 to 10 μm, and more preferably 6 to 9 μm, for example, on a volume basis median diameter.

  When the volume-based median diameter is in the above range, the transfer efficiency is increased, the image quality of halftone is improved, and the image quality of fine lines and dots is improved.

  The volume-based median diameter of particles is measured and calculated using a measuring device in which a data processing computer system (Beckman Coulter) is connected to "Coulter Multisizer TA-III" (Beckman Coulter). It is. Specifically, 0.02 g of toner is added to 20 ml of a surfactant solution (for example, a surfactant solution in which a neutral detergent containing a surfactant component is diluted 10-fold with pure water for the purpose of dispersing the toner). After mixing, ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion, and this toner dispersion is displayed on the beaker containing “ISOTONII” (manufactured by Beckman Coulter) in the sample stand. Pipette until the concentration is 5-10%. Here, a reproducible measurement value can be obtained by setting the concentration range. In the measurement apparatus, the measurement particle count is 25000, the aperture diameter is 50 μm, the frequency value is calculated by dividing the measurement range of 1 to 30 μm into 256, and the volume integrated fraction is 50 % Particle diameter was defined as the volume-based median diameter.

  In addition, with respect to the individual toner particles constituting the toner, the average circularity represented by the following formula (T) is preferably 0.930 to 1.000, more preferably 0, from the viewpoint of improving transfer efficiency. .950 to 0.995.

Formula (T): Average circularity = peripheral length of circle determined from equivalent circle diameter / perimeter length of projected particle image The toner according to the present invention may contain a release agent.

  The release agent used when the release agent is contained in the toner of the present invention is not particularly limited, and examples thereof include polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, carnauba. There may be mentioned wax, sazol wax, rice wax, candelilla wax, jojoba oil wax, beeswax wax and the like.

  As a method for incorporating a release agent in the toner, as described above, a method in which the particles of the first resin are configured to contain a release agent, for example, salting out, agglomeration, and melting to form toner particles. In the attaching step, a method of adding a dispersion liquid in which release agent particles are dispersed in an aqueous medium can be mentioned, and these methods may be combined.

  The content ratio of the release agent in the toner particles is usually 0.5 to 5 parts by mass with respect to 100 parts by mass of the binder resin from the viewpoint of offset prevention effect, translucency and color reproducibility, and preferably Is 1 to 3 parts by mass.

  The particles that have undergone the crosslinking step can be used as toners as they are, but preferably undergo the following washing / drying step and post-treatment step.

(Washing / drying process)
In this step, the toner particles are filtered off from the aqueous medium, unnecessary substances such as surfactants are removed from the toner particles by a cleaning process, and the cleaned toner particles are dried.

(Post-processing process)
In order to improve fluidity, chargeability, cleaning properties, and the like, external additives such as a fluidizing agent and a cleaning aid may be added to the toner particles.

  As the post-treatment agent, for example, inorganic oxide fine particles composed of silica fine particles, alumina fine particles, titanium oxide fine particles, etc., inorganic stearate compound fine particles such as aluminum stearate fine particles, zinc stearate fine particles, or strontium titanate, titanium Inorganic titanic acid compound fine particles such as zinc acid are listed. These can be used individually by 1 type or in combination of 2 or more types.

  These inorganic fine particles are preferably subjected to surface treatment with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like in order to improve heat-resistant storage stability and environmental stability.

  The total amount of these various external additives added is 0.05 to 5 parts by mass, preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the toner. In addition, various external additives may be used in combination.

(Developer)
The toner produced by the production method of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer.

  In the case where the toner produced by the production method of the present invention is used as a two-component developer, the carrier is conventionally a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. From the above, magnetic particles made of a known material can be used, and ferrite particles are particularly preferable. Further, as the carrier, a coat carrier in which the surface of the magnetic particles is coated with a coating agent such as a resin, a binder type carrier in which a magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine resins. Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 20 to 60 μm. The volume-based median 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.

(Image forming method)
The toner produced by the production method of the present invention can be suitably used in an image forming method including a fixing step by a heat and pressure fixing method in which pressure can be applied and heated.

  In this image forming method, specifically, the toner as described above is used, for example, an electrostatic latent image formed on a photoreceptor is developed to obtain a toner image, and this toner image is used as an image support. Then, the toner image transferred onto the image support is fixed on the image support by a fixing process using a thermal pressure fixing method, whereby a printed matter on which a visible image is formed is obtained.

  The application of pressure and heating in the fixing step are preferably simultaneous, and the pressure may be applied first and then heated.

The pressure to be applied to the toner particles constituting the toner image transferred onto the image support is, for example, (i) a contact load between the heating roller and the pressure roller in a heat roller type fixing device described later. May be a pressure at which is 40 to 350N. Further, for example, in the (ii) film heating type fixing device to be described later, it is sufficient that the surface pressure of the fixing belt with respect to the image support is 9 × 10 ^{3 to} 5 × 10 ⁵ N / m ² .

  As the fixing device of the thermal pressure fixing method in the image forming method using the toner according to the present invention, various known devices can be employed. Hereinafter, a heat roller type fixing device and a film heating type fixing device will be described as the thermal pressure fixing device.

(I) Heat roller type fixing device Generally, a heat roller type fixing device is provided with a roller pair of a heating roller and a pressure roller in contact with the heating roller, and the pressure applied between the heating roller and the pressure roller. When the pressure roller is deformed, a so-called fixing nip portion is formed in the deformed portion.

  In general, the heating roller includes a metal core made of a hollow metal roller made of aluminum or the like and a heat source made of a halogen lamp or the like disposed therein, the metal core is heated by the heat source, and the outer peripheral surface of the heating roller is The temperature is adjusted by controlling energization to the heat source so as to be maintained at a predetermined fixing temperature.

  In particular, when used as a fixing device of an image forming apparatus that forms a full-color image that requires a capability of sufficiently melting and mixing a toner image composed of a maximum of four toner layers, a core metal is used as a heating roller. It is preferable to use a material having a high heat capacity and a rubber elastic layer for uniformly melting the toner image on the outer peripheral surface of the metal core.

  The pressure roller has an elastic layer made of a soft rubber such as urethane rubber or silicon rubber.

  As the pressure roller, for example, a metal core made of a hollow metal roller made of aluminum or the like and having an elastic layer formed on the outer peripheral surface of the metal core may be used.

  Furthermore, when the pressure roller is configured to have a metal core, a heat source such as a halogen lamp is disposed inside the pressure roller, and the metal core is heated by the heat source. Alternatively, the temperature may be adjusted by controlling the power supply to the heat source so that the outer peripheral surface of the heat source is maintained at a predetermined fixing temperature.

  As these heating rollers and / or pressure rollers, as the outermost layer, a mold release made of a fluororesin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or the like is used. It is preferable to use a layer formed. The thickness of the release layer can be approximately 10 to 30 μm.

  In such a heat roller type fixing device, the roller pair is rotated and the image support to form a visible image is sandwiched and conveyed in the fixing nip portion, whereby the heating by the heating roller and the pressure in the fixing nip portion are reduced. Thus, an unfixed toner image is fixed on the image support.

(Ii) Film heating type fixing device Generally, a film heating type fixing device is made of, for example, a heating body made of a ceramic heater, a pressure roller, and a heat resistant film between the heating body and the pressure roller. The fixing film is sandwiched, and the pressure roller is deformed by the pressure applied between the heating body and the pressure roller, so that a so-called fixing nip portion is formed in the deformed portion. .

  As the fixing film, a heat-resistant film made of polyimide or the like, a sheet or a belt is used, and the heat-resistant film, sheet or belt made of polyimide or the like is used as a film substrate, and tetrafluoro is formed on the film substrate. A release layer made of a fluororesin such as ethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl ether copolymer (PFA) may be formed, and further, a film substrate and a release layer Between the two, an elastic layer made of rubber or the like may be provided.

  In such a film heating type fixing device, an image support carrying an unfixed toner image is nipped and conveyed together with the fixing film between a fixing film forming a fixing nip portion and a pressure roller. Thus, heating by the heating body through the fixing film and application of pressure at the fixing nip portion are performed, whereby an unfixed toner image is fixed on the image support.

  According to such a film heating type fixing device, the heating body only needs to be energized to generate heat at a predetermined fixing temperature only during image formation. Quick start performance with a short waiting time until image formation can be performed is obtained, power consumption during standby of the image forming apparatus is extremely small, and power saving can be achieved.

(Image support)
The image support used in the image forming method using the toner produced by the production method of the present invention is a coated printing paper such as plain paper, fine paper, art paper or coated paper from thin paper to thick paper. Various types of paper such as commercially available Japanese paper and postcard paper, plastic films for OHP, and cloth can be used, but the invention is not limited to these.

  According to the toner as described above, a crosslinked polymer is contained, and the crosslinked polymer has a characteristic that the bond between the imidazole rings of the triarylimidazole group is cleaved by application of pressure. By applying pressure, the glass transition point is changed to a lowered one, and by applying pressure and heating, a sufficiently low state of elastic modulus can be obtained early on the toner even at a low heating temperature, As a result, sufficient low-temperature fixability can be obtained. On the other hand, in the state before the pressure is applied, the specific crosslinked polymer has heat-resistant storage stability because the micro Brownian motion due to heat is suppressed. Therefore, according to such a toner, sufficient low-temperature fixability can be obtained while heat-resistant storage stability is obtained.

  In addition, according to such a toner, a sufficiently reduced state of the elastic modulus of the crosslinked polymer due to the application of pressure can be obtained at an early stage, so that sufficient high-speed fixability can also be obtained.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. In the following, the volume-based median diameter, peak molecular weight, and glass transition point of the toner were measured by the same method as described above. The peak molecular weight and glass transition point measured using the toner as a measurement sample were used as the peak molecular weight and glass transition point of the crosslinked polymer.

<Preparation of particle dispersion of core resin (first resin) 1 (styrene acrylic resin)>
Reaction liquid <Styrene acrylic resin dispersion>
Styrene 240 parts by weight Butyl acrylate 130 parts by weight Acrylic acid 6 parts by weight Terrestrial decyl mercaptan 24 parts by weight was dissolved in a polyoxyethylene lauryl ether “E-700” (manufactured by Nippon Emulsion) 6 parts by weight. And 10 parts by weight of sodium n-dodecylbenzenesulfonate dissolved in 1550 parts by weight of ion-exchanged water, added in a flask, dispersed and emulsified, and mixed slowly for 10 minutes. Nitrogen substitution was performed by adding 50 parts by mass of ion-exchanged water in which part by mass was dissolved.

  Next, while stirring the inside of the flask with an oil bath until the content reaches 70 ° C. and continuing the emulsion polymerization for 5 hours, the solid content of the core resin (first resin) particles is 20 parts by mass. As a result, a particle dispersion of the core resin (first resin) 1 (styrene acrylic resin) was obtained. The volume-based median diameter of the particles was 152 nm.

  Moreover, the glass transition point of the obtained core resin (first resin) 1 was 21 ° C., and the peak molecular weight determined by GPC measurement was 19,200.

<Preparation of particle dispersion of core resin (first resin) 2 (polyester resin)>
A flask equipped with a stirrer, a nitrogen inlet tube, a temperature controller, and a rectifying column was charged with the following polycarboxylic acid monomer and polyhydric alcohol monomer, and this reaction solution was heated to 190 ° C. over 1 hour, and the reaction system After confirming that the inside was uniformly stirred, catalyst Ti (OBu) ₄ (0.003 mass% with respect to the total amount of the carboxylic acid component of the polyester resin) was added.

Reaction solution (polycarboxylic acid monomer)
Terephthalic acid 30 parts by weight Isophthalic acid 3 parts by weight Adipic acid 3 parts by weight (polyhydric alcohol monomer)
2,2-bis (4-hydroxyphenyl) propane propylene oxide 2-mole adduct
75 parts by mass 2,2-bis (4-hydroxyphenyl) propaneethylene oxide 2 mol adduct
25 parts by mass Further, while distilling off the generated water, the temperature was increased to 240 ° C. over 6 hours from the same temperature, and the dehydration-condensation reaction was continued at 240 ° C. for another 6 hours to carry out polymerization. 1st resin) was obtained.

  The obtained core resin 2 (first resin) had a glass transition point of 40 ° C. and a peak molecular weight of 18,000 as measured by GPC.

  400 parts by mass of “core resin 2 (first resin)” was added to 1700 parts by mass of ethyl acetate, and the mixture was heated to 70 ° C. and dissolved and mixed to obtain a “core resin solution”. Separately, 2000 parts by weight of ion-exchanged water and 4.8 parts by weight of sodium dodecyl sulfate were stirred and dispersed to prepare “Aqueous Phase (1)” which becomes a continuous phase. In this “water phase (1)”, “resin solution for core” is added while stirring with “TK homomixer Mark II2.5 type” (manufactured by Primics Co., Ltd.), and “oil droplets” are adjusted by adjusting the rotation speed of stirring. (1) "was prepared. Then, it distilled under reduced pressure at 50 degreeC and removed ethyl acetate, and obtained the core particle dispersion liquid 2 (solid content is 20 parts by mass) of the core resin (first resin) 2 (polyester resin). The volume-based median diameter was 180 nm.

(Preparation of colorant particle dispersion)
6 parts by mass of a nonionic surfactant “E-700” (Japan Emulsion Co., Ltd.) is stirred and dissolved in 200 parts by mass of ion-exchanged water, and a cyan pigment (CI Pigment Blue) is used as a colorant while continuing stirring. 15.3) 50 parts by mass were gradually added, and then dispersed for 10 minutes with a homogenizer “Ultra Turrax” (manufactured by IKA) to prepare a colorant particle dispersion in which colorant particles were dispersed. . When the particle diameter of the colorant particles in this colorant particle dispersion was measured using “MICROTRAC UPA 150” (manufactured by Nikkiso Co., Ltd.), the volume-based median diameter was 180 nm.

(Preparation of release agent particle dispersion)
6 parts by mass of a nonionic surfactant “E-700” (Japan Emulsion Co., Ltd.) is stirred and dissolved in 200 parts by mass of ion-exchanged water, and paraffin wax “HNP-0190” ( (Nippon Seiki Co., Ltd.) 50 parts by mass was added, heated to 95 ° C., and then subjected to a dispersion treatment for 10 minutes with a homogenizer “Ultra Turrax T50” (manufactured by IKA) to disperse the release agent particles. A release agent particle dispersion was prepared. When the particle diameter of the release agent particles in this release agent particle dispersion was measured using “MICROTRAC UPA 150” (manufactured by Nikkiso Co., Ltd.), the volume-based median diameter was 250 nm.

<Synthesis of vinyl-triphenylimidazole compound>
[Synthesis Example of Vinyl-Triphenylimidazole Compound (1)]
In the reaction vessel,
Benzoin (2-hydroxy-1,2-diphenylethanone) 1609 parts by weight 3-vinylbenzaldehyde 1002 parts by weight Ammonium acetate 5838 parts by weight Boron tetrafluoride 1603 parts by weight, and heated to 100 ° C., Stirring was continued for 1.5 hours. After completion of the reaction, the reaction mixture was diluted with water, and the resulting solid was filtered, washed repeatedly with water, dried, and then subjected to silica gel column chromatography with a mixed solvent of hexane / ethyl acetate (mass ratio 9: 1). After purification by using, it was recrystallized with a mixed solvent of methanol / dichloroethane (mass ratio 9: 1) to obtain a vinyl-triphenylimidazole compound (1).

[Synthesis Example of Vinyl-Triphenylimidazole Compound (2)]
In the reaction vessel,
A mixed solution consisting of 3090 parts by mass of 2- (p-aminophenyl) 4,5-diphenylimidazole and 925 parts by mass of methacrylic acid chloride was added, and stirring was continued at 10 ° C. for 1.5 hours. After completion of the reaction, it is diluted with 0.1N aqueous sodium hydroxide solution, and the resulting solid is filtered, washed repeatedly with water, dried, and then mixed with a mixed solvent of hexane / ethyl acetate (mass ratio 9: 1). After purification using silica gel column chromatography, recrystallization with a mixed solvent of methanol / dichloroethane (mass ratio 9: 1) gave a vinyl-triphenylimidazole compound (2).

[Synthesis Example of Vinyl-Triphenylimidazole Compound (3)]
In Synthesis Example (2) of the vinyl-triphenylimidazole compound, 3100 mass of 2- (p-hydroxyphenyl) 4,5-diphenylimidazole instead of 3090 mass parts of 2- (p-aminophenyl) 4,5-diphenylimidazole A vinyl-triphenylimidazole compound (3) was obtained in the same manner except that the part was used.

[Synthesis Example of Vinyl-Triphenylimidazole Compound (4)]
In the synthesis example (2) of the vinyl-triphenylimidazole compound, the vinyl-triphenylimidazole compound (4) was obtained in the same manner except that 710 parts by weight of vinyl isocyanate was used instead of 925 parts by weight of methacrylic acid chloride. It was.

[Synthesis Example of Vinyl-Triphenylimidazole Compound (5)]
In Synthesis Example (2) of the vinyl-triphenylimidazole compound, instead of 3090 parts by mass of 2- (p-aminophenyl) 4,5-diphenylimidazole and 925 parts by mass of methacrylic acid chloride, 2- (p-hydroxyphenyl) 4 , 5-diphenylimidazole A vinyl-triphenylimidazole compound (5) was obtained in the same manner except that 3100 parts by mass and vinyl isocyanate 710 parts by mass were used.

<Preparation of dispersion of shell layer particles>
[Preparation of Shell Layer Particle Dispersion a (Preparation of Shell Resin Dispersion According to the Present Invention)]
A flask equipped with a stirrer, a nitrogen inlet tube, a temperature controller, and a rectifying column was charged with the following polycarboxylic acid monomer and polyhydric alcohol monomer, and this reaction solution was heated to 190 ° C. over 1 hour, and the reaction system After confirming that the inside was uniformly stirred, catalyst Ti (OBu) ₄ (0.003 mass% with respect to the total amount of the carboxylic acid component of the polyester resin) was added.

(Polyvalent carboxylic acid monomer)
Terephthalic acid 30 parts by weight Fumaric acid 1 part by weight Adipic acid 5 parts by weight (polyhydric alcohol monomer)
2,2-bis (4-hydroxyphenyl) propane propylene oxide 2-mole adduct
75 parts by mass 2,2-bis (4-hydroxyphenyl) propaneethylene oxide 2 mol adduct
25 parts by mass Further, while distilling off the generated water, the temperature was increased from the same temperature to 6 hours, and the temperature was increased to 240 ° C. The dehydration condensation reaction was continued at 240 ° C for another 6 hours to conduct polymerization. Resin b was obtained.

  The obtained amorphous polyester resin b had a glass transition point of 40 ° C. and a peak molecular weight of 8,000 as measured by GPC.

  200 parts by mass of “amorphous polyester resin b” is added to 750 parts by mass of ethyl acetate, heated to 70 ° C., dissolved, mixed, and “polyester shell first resin solution (shell first resin solution according to the present invention”). Got.

  Further, the following vinyl compound solution containing a vinyl-triphenylimidazole compound was added to and dissolved in the polyester shell first resin solution, and further 50 parts by mass of ethyl acetate in which 4 parts by mass of azobisisobutyronitrile was dissolved. I put it in.

Vinyl compound solution Vinyl-triphenylimidazole compound (1) 42 parts by mass Styrene 100 parts by mass Butyl acrylate 40 parts by mass Acrylic acid 3 parts by mass Tertiary decyl mercaptan 12 parts by mass The solution is heated until it is heated, and solution polymerization is continued for 5 hours to obtain a “polyester resin (third resin) -styrene acrylic resin (second resin) mixed solution (shell second resin solution according to the present invention)”. It was.

  Separately, 2000 parts by weight of ion-exchanged water and 4.8 parts by weight of sodium dodecyl sulfate were stirred and dispersed to prepare “Surfactant aqueous solution (1)” that becomes a continuous phase. In this “surfactant aqueous solution (1)”, while stirring with “TK homomixer Mark II2.5 type” (manufactured by Primics Co., Ltd.), “polyester resin (third resin) -styrene acrylic resin (second resin)” The mixed solution (shell second resin solution according to the present invention) "was charged, and oil droplets were prepared by adjusting the stirring rotation speed. Thereafter, the mixture was distilled off under reduced pressure at 50 ° C. to remove ethyl acetate to obtain a dispersion a (shell resin dispersion according to the present invention) of resin particles for shell layers. The volume-based median diameter was 150 nm.

[Dispersion B of Resin Particles for Shell Layer (Preparation of Shell Resin Dispersion According to the Present Invention)]
Preparation of dispersion a of resin particles for shell layer, except that vinyl-triphenylimidazole compound (1) prepared in resin particle core resin dispersion a for shell is changed to vinyl-triphenylimidazole compound (2) Similarly, a dispersion b of resin particles for shell layer was prepared.

[Dispersion c of Shell Particle Resin Particles (Preparation of Shell Resin Dispersion According to the Present Invention)]
Preparation of dispersion a of resin particles for shell layer, except that vinyl-triphenylimidazole compound (1) prepared in resin particle core resin dispersion a for shell is changed to vinyl-triphenylimidazole compound (3) Similarly, a dispersion c of resin particles for shell layer was prepared.

[Dispersion d of resin particles for shell layer (production of shell resin dispersion according to the present invention)]
A flask equipped with a stirrer, a nitrogen inlet tube, a temperature controller, and a rectifying column was charged with the following polycarboxylic acid monomer and polyhydric alcohol monomer, and this reaction solution was heated to 190 ° C. over 1 hour, and the reaction system After confirming that the inside was uniformly stirred, catalyst Ti (OBu) ₄ (0.003 mass% with respect to the total amount of the carboxylic acid component of the polyester resin) was added.

(Polyvalent carboxylic acid monomer)
Terephthalic acid 30 parts by weight Adipic acid 6 parts by weight (polyhydric alcohol monomer)
2,2-bis (4-hydroxyphenyl) propane propylene oxide 2-mole adduct
75 parts by mass 2,2-bis (4-hydroxyphenyl) propaneethylene oxide 2 mol adduct
25 parts by mass Further, while distilling off the generated water, the temperature was increased from the same temperature to 6 hours, and the temperature was increased to 240 ° C. The dehydration condensation reaction was continued at 240 ° C for another 6 hours to conduct polymerization. Resin c was obtained.

  200 parts by mass of “amorphous polyester resin c” is added to 750 parts by mass of ethyl acetate, heated to 70 ° C., dissolved and mixed, and “polyester shell second resin solution (shell first resin solution according to the present invention)” After 1 part of 2-isocyanatoethyl methacrylate was added and 1 hour had passed, a vinyl compound solution in which the following vinyl-triphenylimidazole compound and vinyl compound solution were mixed and dissolved was added dropwise. Furthermore, 50 parts by mass of ethyl acetate in which 4 parts by mass of azobisisobutyronitrile was dissolved was added.

Vinyl compound solution Vinyl-triphenylimidazole compound (3) 42 parts by mass Styrene 100 parts by mass Butyl acrylate 40 parts by mass Acrylic acid 3 parts by mass Tertiary decyl mercaptan 12 parts by mass By heating until the solution is continued and solution polymerization is continued for 5 hours, a “polyester resin (third resin) -styrene acrylic resin (second resin) mixed solution (4) (shell second resin solution according to the present invention)” is obtained. "

  Separately, 2000 parts by mass of ion-exchanged water and 4.8 parts by mass of sodium dodecyl sulfate were stirred and dispersed to prepare a “surfactant aqueous solution (4)” that becomes a continuous phase. In this “surfactant aqueous solution (4)”, while stirring with “TK homomixer Mark II2.5 type” (manufactured by Primics Co., Ltd.), “polyester resin (third resin) -styrene acrylic resin (second resin)” The mixed solution (4) (shell second resin solution according to the present invention) "was added, and oil droplets were prepared by adjusting the stirring rotation speed. Thereafter, this was distilled off under reduced pressure at 50 ° C. to remove ethyl acetate, and a particle dispersion d of resin for shell layer was obtained.

[Preparation of dispersion e of resin particles for shell layer]
Dispersion liquid of shell layer resin particles as in preparation of dispersion liquid d of shell layer resin particles, except that the polyhydric alcohol monomer prepared in dispersion liquid d of shell layer resin particles was changed as follows. e was produced.

(Polyhydric alcohol monomer)
2,2-bis (4-hydroxyphenyl) propane propylene oxide 2-mole adduct
75 parts by mass 2,2-bis (4-hydroxyphenyl) propaneethylene oxide 2 mol adduct
20 parts by mass Glycerin 1 part by mass [Preparation of dispersion f of resin particles for shell layer]
Preparation of dispersion a of shell layer resin particles a, except that vinyl-triphenylimidazole compound (1) prepared in dispersion a of resin particles for shell layer was changed to vinyl-triphenylimidazole compound (4) Similarly, a dispersion f of resin particles for shell layer was prepared.

[Preparation of dispersion g of resin particles for shell]
The shell is the same as the preparation of the shell resin particle dispersion a except that the vinyl triphenylimidazole compound (1) prepared in the shell resin particle dispersion a is changed to the vinyl triphenylimidazole compound (5). A resin particle dispersion g was prepared.

[Preparation of dispersion h of resin particles for shell layer]
After producing the resin particle core resin dispersion c for shells, the dispersion is cooled to 10 ° C. at a cooling rate of −5 ° C./min, 10 parts by mass of 1% aqueous sodium hypochlorite solution is added, and the temperature is 10 ° C. Reaction was performed for 6 hours to obtain a dispersion h of resin particles for the shell layer. Further, the dispersion h of the resin particles for the shell layer formed a crosslinked structure, and thus was substantially insoluble in tetrahydrofuran.

<Preparation of toner particles>
[Production of Toner Particles (1)]
272 parts by mass (in terms of solid content) of the core resin 1 particles, 2200 parts by mass of ion-exchanged water, 98 parts by mass of the colorant particle dispersion, and 243 parts by mass of the release agent fine particle dispersion were added to a thermometer, a cooling tube, nitrogen It put into a separable flask provided with an introducing device and a stirring device. Furthermore, the pH in which the aqueous sodium hydroxide solution (25% by mass) was added was adjusted to 10 while maintaining the temperature in the system at 30 ° C.

  Next, an aqueous solution in which 54.3 parts by mass of magnesium chloride hexahydrate is dissolved in 54.3 parts by mass of ion-exchanged water is added, and then the temperature in the system is raised to 60 ° C. to obtain resin particles. And the aggregation reaction of the colorant particles was started.

After the start of the agglutination reaction, sampling is periodically performed, and the particle size distribution measuring device “Coulter Multisizer 3” (manufactured by Beckman Coulter) is used, and the median diameter (D ₅₀ ) on the volume basis of the particles is 6.0 μm Then, 857 parts by mass of a dispersion a of resin particles for a shell layer forming a shell layer of the toner was added. When the shell layer was formed on the toner surface, 20.1 parts by mass of ethylenediaminetetraacetic acid was added. The circularity of the toner particles at this time was 0.92.

  The temperature was raised, and when the circularity of the toner particles reached 0.96, the suspension was cooled to 10 ° C. under the condition of 6 ° C./min, 10 parts by mass of 1% sodium hypochlorite aqueous solution was added, The reaction was carried out at a temperature of 10 ° C. for 6 hours. The product in the dispersion was filtered, washed thoroughly with ion exchange water, and then dried to obtain particles crosslinked with a second resin to be dried.

  Next, the produced toner particle dispersion was subjected to solid-liquid separation with a basket-type centrifuge “MARK III type” (model number 60 × 40) (manufactured by Matsumoto Kikai Kogyo Co., Ltd.) to form a toner wet cake. Thereafter, the toner washing and solid-liquid separation were repeated until the electric conductivity of the filtrate reached 15 μS / cm or less.

  Subsequently, the wet cake was transferred to an airflow dryer “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content reached 0.5% by mass. The drying process was performed by blowing an air current of 40 ° C. and 20% RH. The dried toner was allowed to cool to 24 ° C., and 1.0 part by mass of hydrophobic silica was mixed with 100 parts by mass of the toner using a Henschel mixer. The peripheral speed of the rotary blade was 24 m / s, and the mixture was mixed for 20 minutes, and then passed through a 400 MESH sieve. The obtained toner is defined as toner particles (1).

[Production of Toner Particles (2)]
The toner particles (2) are prepared in the same manner as the toner particles (1) except that the dispersion a of the shell layer resin particles prepared with the toner particles (1) is changed to the resin particle dispersion b of the shell layer. did.

[Production of Toner Particles (3)]
The toner particles (3) were prepared in the same manner as the toner particles (1) except that the shell layer resin particle dispersion a prepared with the toner particles (1) was changed to the shell layer resin particle dispersion c. .

[Production of Toner Particles (4)]
Toner particles (4) were prepared in the same manner as toner particles (1) except that the resin particle dispersion a for shell layer prepared in toner particles (1) was changed to resin particle dispersion d for shell layer. .

[Production of Toner Particles (5)]
The toner particles (5) were prepared in the same manner as the toner particles (1) except that the shell layer resin particle dispersion a prepared with the toner particles (1) was changed to the shell layer resin particle dispersion e. .

[Production of Toner Particles (6)]
The toner particles (6) were prepared in the same manner as the toner particles (1) except that the shell layer resin particle dispersion a prepared with the toner particles (1) was changed to the shell layer resin particle dispersion f. .

[Production of Toner Particles (7)]
The toner particles (7) were prepared in the same manner as the toner particles (1) except that the shell layer resin particle dispersion a prepared with the toner particles (1) was changed to the shell layer resin particle dispersion g. .

[Production of Toner Particles (8)]
Toner particles (8) were produced in the same manner as toner particles (1) except that the core particles 1 produced with the toner particles (1) were changed to the core particles 2.

[Production of Toner Particles (9)]
Toner particles (9) were prepared in the same manner as the toner particles (8), except that the shell layer resin particle dispersion a prepared with toner particles (8) was changed to the shell layer resin particle dispersion b. .

[Production of Toner Particles (10)]
The toner particles (10) were prepared in the same manner as the toner particles (8) except that the shell layer resin particle dispersion a prepared with the toner particles (8) was changed to the shell layer resin particle dispersion c. .

[Production of Toner Particles (11)]
Toner particles (11) were prepared in the same manner as toner particles (8), except that the shell layer resin particle dispersion a prepared with toner particles (8) was changed to shell layer resin particle dispersion d. .

[Production of Toner Particles (12)]
The toner particles (12) were prepared in the same manner as the toner particles (8) except that the shell layer resin particle dispersion a prepared with the toner particles (8) was changed to the shell layer resin particle dispersion e. .

[Production of Toner Particles (13)]
Toner particles (13) were prepared in the same manner as toner particles (8), except that the shell layer resin particle dispersion a prepared with toner particles (8) was changed to shell layer resin particle dispersion f. .

[Production of Toner Particles (14)]
Toner particles (14) were prepared in the same manner as toner particles (8), except that the shell layer resin particle dispersion a prepared with toner particles (8) was changed to shell layer resin particle dispersion g. .

[Production of Toner Particles (15)]
Toner particles (15) were prepared in the same manner as toner particles (3) except that sodium hypochlorite prepared in toner particles (3) was changed to potassium ferricyanide.

[Production of Toner Particles (16)]
Toner particles (16) were prepared in the same manner as toner particles (10) except that sodium hypochlorite prepared in toner particles (10) was changed to potassium ferricyanide.

[Production of Comparative Toner Particles (1)]
The shell layer resin particle dispersion c prepared with toner particles (3) is changed to the shell layer resin particle dispersion h, sodium hypochlorite is not added, and the shelling temperature rises to 95 ° C. I let you. Otherwise, toner particle comparison 1 was prepared in the same manner as toner particle (3).

[Production of Comparative Toner Particles (2)]
Comparative toner particles (2) were prepared in the same manner as the comparative toner particles (1) except that the core particles 1 prepared in the comparative toner particles (1) were changed to the core particles 2.

  Further, the toner used in Example 1 of Patent Document 1 was also prepared to obtain comparative toner particles (3).

(Preparation of two-component developer)
100 parts by mass of ferrite particles (volume-based median diameter: 50 μm (manufactured by Powdertech)) and 4 parts by mass of methyl methacrylate-cyclohexyl methacrylate copolymer resin (volume-based median diameter of primary particles: 85 nm) The mixture was placed in a stirring blade type high-speed stirring device and mixed for 15 minutes under the conditions of the peripheral speed of the stirring blade: 8 m / s and the temperature: 30 ° C., then the temperature was raised to 120 ° C. and stirring was continued for 4 hours. Then, it cooled and the resin-coated carrier was produced by removing the fragment of methyl methacrylate-cyclohexyl methacrylate copolymer resin using a 200 mesh sieve.

  The resin-coated carrier is mixed with each of the toner particles (1) to (16) and the comparative toner particles (1), (2), and (3) so that the toner concentration becomes 7% by mass, and developed. Agents (1) to (16) and Comparatives 1, 2, and 3 were prepared.

(Evaluation)
Evaluation items (A) to (C) below were evaluated using Developers (1) to (16) and Comparatives 1, 2, and 3. The results are shown in Table 1.

(A) Low-temperature fixability A commercially available multifunction machine “bizhub PRO C6500” (manufactured by Konica Minolta Business Technologies) is used as an image forming apparatus, and developers (1) to (16) are used as developers in this apparatus, respectively. In addition, the developer (1) and (2) for comparison are mounted, and the surface temperature of the fixing heating member in the fixing unit of the heat roll fixing method is changed in increments of 5 ° C. within the range of 80 to 150 ° C. In an environment of normal temperature and normal humidity (temperature 20 ° C., humidity 50% RH), image formation was performed using 350 g of paper as an image support, and a solid image with an image density of 0.8 was obtained as a visible image. . Thereafter, the fixing solid image is folded using a folding machine, air of 0.35 MPa is blown onto the fixing solid image, the crease state is evaluated in five stages with reference to a limit sample, and the fixing temperature of rank 3 is set as the lower limit fixing temperature. did. Rank 5: No peeling at all folds, Rank 4: Peeling according to some folds, Rank 3: Thin line peeling according to the folds, Rank 2: Thick peeling according to the folds, Rank 1: Large peeling on the image.

(B) Heat-resistant storage property Take 0.5 g of toner in a 10 ml glass bottle with an inner diameter of 21 mm, close the lid, shake it 600 times at room temperature using a tap denser “KYT-2000” (manufactured by Seishin Enterprise), and then remove the lid. It was left for 2 hours in an environment of temperature 55 ° C. and humidity 35% RH. Next, place the toner on a 48 mesh (350 μm aperture) sieve, taking care not to crush it, set it on a powder tester (manufactured by Hosokawa Micron), fix it with a press bar and knob nut, and adjust the vibration strength to 1 mm. After adjusting and applying vibration for 10 seconds, the amount of residual toner remaining on the sieve was measured, and the toner aggregation rate was calculated by the following formula (1) and evaluated.

Formula (1): toner aggregation rate (%) = {residual toner amount (g) /0.5 (g)} × 100
In addition, when the toner aggregation rate is less than 15%, it is judged that the heat resistant storage property of the toner is extremely good, and when the toner aggregation rate is 15% or more and 20% or less, the heat resistant storage property of the toner is good. If the toner aggregation rate exceeds 20%, it is determined that the toner has poor heat storage stability and cannot be practically used.

(C) Toner scattering prevention property The toner particle strength was determined as follows and used as an index of toner scattering prevention property.

  A two-component developer is set in a developing device of a commercially available digital copying machine “bizhub 920” (manufactured by Konica Minolta Business Technologies), and an electrostatic latent image is not formed on the photosensitive member, that is, under a potential condition where toner is not developed. An agitation test is performed for agitation for a period of time, and then the toner is taken out, and the particle size distribution of the toner is measured using a flow type particle image analyzer “FPIA-2100” (manufactured by Sysmec Co., Ltd.). The particle strength index represented by the following formula (2) was calculated and evaluated based on the particle strength index.

Formula (2): Particle strength index = {(number of particles of 1 μm or less) / (number of whole particles)} × 100
Prior to the stirring test, all developers had a particle strength index of less than 1. When the particle strength index after the agitation test is less than 9, the toner has sufficient particle strength, and the occurrence of carrier contamination is suppressed without generating crushed fine particles of toner particles, thereby obtaining sufficient stress resistance. As a result, it is judged that the replacement cycle of the two-component developer becomes long. On the other hand, when the particle strength index exceeds 9, the surface of the carrier particle is observed when the two-component developer is visually observed with an electron microscope. The state where the toner particles are predominantly covered is observed, and the chances of the carrier particles and the toner particles being triboelectrically charged are greatly reduced. Judged not.

  From Table 3, the toner manufactured by the manufacturing method of the present invention is a simple method in which the surface of the core-shell type toner is treated with an oxidant solution, and can be shelled more efficiently, resulting in productivity. As well as having excellent heat-resistant storage stability, it has sufficient low-temperature fixability, high particle strength, and excellent toner scattering resistance.

Claims (6)

A toner production method for producing a core-shell type toner having a core layer containing a first resin and a colorant and having a shell layer on the core layer, the method comprising the first resin and the colorant A core resin dispersion containing core particles, a shell resin dispersion containing particles for a shell layer containing a second resin having a triarylimidazole group represented by the following general formula (1) and a third resin A shelling step of mixing the solution with the solution to form the shell layer A by covering the core particles with the particles for the shell layer, and treating the shell layer A with an oxidizing agent solution containing an oxidizing agent. A toner production method comprising a crosslinking step of crosslinking two resins.

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. ]   The method for producing a toner according to claim 1, wherein the third resin is a polyester resin.   The shell layer particles include a dissolution step of preparing the shell first resin solution by dissolving the third resin in an organic solvent, and a shell second resin containing the shell first resin solution and the second resin. A mixing step of preparing a solution, wherein the shell second resin solution is dispersed in an aqueous medium to prepare a shell second resin solution dispersion in which droplets of the shell second resin solution are dispersed in the aqueous medium. 3. The method according to claim 2, wherein the organic solvent is removed from the dispersion step and the shell second resin solution dispersion to produce a resin particle. Toner manufacturing method.   4. The method for producing a toner according to claim 3, wherein the second resin contained in the shell second resin solution is a resin synthesized by polymerization in the shell first resin solution. 5. The resin according to claim 1, wherein the second resin is a resin obtained by polymerization using a polymerizable monomer represented by the following general formula (2). Toner production method.

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. R ⁴ represents a hydrogen atom or a methyl group. L represents a single bond or a divalent linking group. ] A toner produced by the toner production method according to claim 1, comprising a core layer containing the first resin and the colorant, and the core layer on the core layer. It has a shell layer containing a second resin having a triarylimidazole group represented by the general formula (1) and a polyester resin, and the surface of the shell layer is a crosslinked structure represented by the following general formula (3) A toner characterized by comprising:

[Wherein R ¹ represents a hydrogen atom or a chlorine atom. R ² and R ³ represent a hydrogen atom, a chlorine atom or a methoxy group. R ⁴ represents a hydrogen atom or a methyl group. L represents a single bond or a divalent linking group. ]