JP2008046464A - Toner for electrostatic latent image development, and method for manufacturing the same, and image forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner which, even at a high-speed printing, satisfies low-temperature fixability without image stains, ensures releasability without adhesion to a fixing roller, and solves the problem of the black spots and white streaks, and to provide a method for manufacturing the same and an image forming method that uses the same. <P>SOLUTION: The toner for electrostatic latent image development contains at least a binder resin and a release agent, wherein the dispersion diameter Ws (nm) of the release agent existing within 0.5 μm from the toner surface and a dispersion diameter Wc (nm) of the release agent existing outside this range have relation Wc>Ws, where Ws is ≥50 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic latent image developing toner, a manufacturing method thereof, and an image forming method using the same.

  In recent years, in electrophotographic multifunction peripherals and printers, there has been a demand for an oilless fixing device that eliminates the need for a silicon oil tank or a coating device in the fixing device because of the simplicity of the device and ease of maintenance. Development of a release agent-containing toner is in progress. In order to improve the releasability from, for example, paper, which becomes an image support at the time of fixing by using a release agent-containing toner, adjustment of the dispersion diameter (domain diameter) of the release agent in the toner, Studies such as the presence of a mold have been made (see, for example, Patent Documents 1 and 2).

On the other hand, energy saving is sought, and the fixing device with the largest energy consumption is focused on the electrophotographic apparatus, and the fixing at a low temperature is being promoted rapidly. In addition, the demand for print-on-demand is increasing, and the printing speed has been increased. When the above-mentioned toner is applied to an image forming apparatus in which the printing speed is increased by a fixing device of a low-temperature fixing design, image contamination due to fixing offset / fixing rate, black spots due to toner particle aggregates, mold release There is a problem that white streaks are generated due to filming of the agent on the photosensitive member and the intermediate transfer belt.
JP-A-7-31470 JP 2001-235895 A

  The present invention has been made to solve the above problems.

  That is, the present invention is a toner that satisfies the low-temperature fixability that does not cause image smearing even during high-speed printing, ensures releasability without winding around the fixing roller, and solves the problems of black spots and white streaks. It is an object to provide a manufacturing method and an image forming method using the same.

  The object of the present invention is achieved by adopting the following configuration.

(1)
In an electrostatic latent image developing toner containing at least a binder resin and a release agent, a release agent dispersion diameter Ws (nm) existing within 0.5 μm from the toner surface, and a release agent existing outside the above range The relationship with the dispersion diameter Wc (nm) is Wc> Ws
However, the toner for developing an electrostatic latent image, wherein Ws ≧ 50 nm.

(2)
The electrostatic latent image developing toner according to (1), wherein 1.5 ≦ Wc / Ws ≦ 5.

(3)
The toner for developing an electrostatic latent image according to (1) or (2), wherein the release agent forming Ws contains a polar release agent as a main component.

(4)
Standard deviation of the dispersion diameter of the release agent forming Ws D. (Ws) is 15 or more and less than 150, and the standard deviation S.D. of the dispersion diameter of the release agent that forms Wc. D. The electrostatic latent image developing toner according to any one of (1) to (3), wherein (Wc) is 20 or more and less than 250.

(5)
In the method for producing a toner for developing an electrostatic latent image according to any one of (1) to (4), a core toner surface containing a resin fine particle containing a release agent and a pigment produced by a miniemulsion polymerization method is provided. A method for producing a toner for developing an electrostatic latent image, wherein polymer particles obtained by adding a polymerizable monomer in the presence of release agent particles and polymerizing are adhered and fused.

(6)
An image forming method using the toner according to any one of (1) to (5), wherein a printing speed is 300 mm / sec or more.

  According to the present invention, a toner and a manufacturing method that satisfy low-temperature fixability that does not cause image smearing even during high-speed printing, ensure releasability without winding around the fixing roller, and solve the problems of black spots and white streaks And an image forming method using the same.

  The effects of the present invention, the compounds used and the production methods thereof will be further described.

  The reason why the effects of the present invention can be obtained by the configuration of the present invention is considered as follows.

  In order to improve releasability against low-temperature fixing, it is necessary for the release agent to exist as a domain having a certain size in the toner.

  However, when a release agent having a large domain diameter is present on the toner surface, the release agents adhere to each other due to external pressure or heating during toner storage. If this happens, the toner particles will stick together and the heat-resistant storage stability of the toner will be reduced, resulting in blocking, or part of the release agent near the toner surface will adhere to the photoconductor and intermediate transfer body, causing black spots. There has been a problem of occurrence and so-called filming phenomenon.

  Therefore, in the present invention, the dispersion diameter of the release agent is increased outside the vicinity of the toner surface to improve the releasability at low temperature fixing, and the dispersion diameter of the release agent is decreased near the toner surface. This ensures releasability as well as adhesion to paper during low-temperature fixing, and at the same time, there are image defects such as black spots caused by reduced heat-resistant storage of toner and white streaks caused by filming. It was possible to obtain a toner that solved the problem that occurred.

[Means for setting Wc> Ws]
In order to solve the problems of the present invention, the relationship between the release agent dispersion diameter Ws (nm) existing within 0.5 μm from the toner surface and the release agent dispersion diameter Wc (nm) existing outside the above range is described. , Wc> Ws. For this purpose, a so-called core-shell type toner having a core-shell structure is preferable.

  As a method for producing the toner, a polymerization / aggregation type toner production method in which resin particles having a different design from the resin particles for the core (core toner) and the resin particles for the shell can be adopted is preferable. A preferred method for producing the core resin particles is a mini-emulsion polymerization method, and a preferred method for producing the shell resin particles is a wax seed polymerization method.

  Specifically, a toner production method using miniemulsion polymer particles as core resin particles and wax seed polymer particles as shell resin particles will be described below.

  The mini-emulsion polymerization method involves adding a radically polymerizable monomer solution in which a release agent (wax) is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less. It refers to a method in which the formation of oil droplets by imparting dynamic energy and then the polymerization proceeds by radicals from a water-soluble radical polymerization initiator.

  In the wax seed polymerization method, a release agent is added to an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less, and the release agent is dispersed by adding mechanical energy. It refers to a method in which polymerization is advanced by adding a polymerizable monomer after adding an initiator and using a release agent as a seed.

  Further, in the present invention, a multistage polymerization method may be used as a method for producing resin fine particles, and the case where the miniemulsion polymerization method is used as part of the multistage polymerization is also included in the miniemulsion polymerization method. Similarly, the case where the wax seed polymerization method is used as part of the multi-stage polymerization is also included in the wax seed polymerization method.

  First, a method for adjusting Wc will be described.

  When the core particles are prepared by miniemulsion polymerization, the dispersion diameter and particle size distribution of the release agent in the resin fine particles can be controlled by the amount of surfactant at the time of dispersion in miniemulsion polymerization, the energy to be applied, and the dispersion time. it can.

  Also in the ripening process at the time of association, the fluidization of the resin occurs inside the toner particles, and the release agents come into contact with each other to easily form a domain, thereby changing the release agent dispersion diameter and the particle size distribution in the toner particles. be able to. Factors that control the domain formation of the release agent accompanying the fluidization of the resin in the aging process include the melting point of the release agent and the thermal energy applied during aging. For example, when the thermal energy applied at the time of aging is increased, the domain formation of the release agent is progressed by increasing the domain size of the release agent, and at the same time, the uniformity of the particle size distribution can be improved.

  That is, the dispersion diameter and the particle size distribution of the release agent in the core toner can be controlled by the dispersion diameter and the particle size distribution of the release agent in the resin fine particles and the domain formation in the aging process at the time of association.

  Next, a method for adjusting Ws will be described.

  The number average particle size of the release agent-dispersed particles contained in the shell may be 50 nm or more, preferably 100 to 500 nm, more preferably 150 to 300 nm. If it is less than 50 nm, the function as a mold release agent cannot be exhibited, which is not preferable.

  The release agent contained in the shell is disposed near the toner surface. When the release agent dispersion diameter is large, toner aggregation and filming occur due to exposure of the release agent, which is not preferable. The reason why the release agent dispersion diameter is preferably 100 to 500 nm and more preferably 150 to 300 nm is that the effect as a release agent can be sufficiently exhibited and the exposure of the release agent can be prevented.

  In addition, when particles having a large dispersion diameter or small particles are present and the uniformity of the release agent dispersion diameter is low, toner aggregation or filming due to exposure of the release agent may occur, It is not preferable because the effect is small, and it is preferable that the uniformity of the release agent dispersion diameter is high. Also, if the particle size distribution of the release agent dispersion diameter is high in uniformity, the cohesive force of the shell fine particles on the core toner is aligned in the shelling step, so that a uniform shell layer can be formed.

  In order to prevent an increase in the dispersion diameter of the release agent, it is necessary to incorporate the release agent into the resin and prevent the release agent from being exposed. For this purpose, as described above, a seed polymerization method using a release agent as seed particles is preferable.

  In the seed polymerization method, the dispersion diameter and particle size distribution of the release agent can be controlled by the dispersing device, the amount of the surfactant, the applied dispersion energy and time. For example, when a homomixer is used, the dispersion diameter of the release agent emulsion can be easily controlled by adjusting the number of rotations. In addition, if the stirring time is too short, the size of each emulsion varies and a uniform particle size distribution cannot be obtained. Therefore, it is preferable to take a long stirring time.

  The apparatus for forming the release agent emulsion is not particularly limited, but it is preferable to use an ultrasonic disperser, a mechanical homogenizer, a manton gourin or a pressure type homogenizer that can apply a high-speed shear force under pressure. Use of a pressure disperser is preferable because the uniformity of the particle size distribution is increased.

(Release agent dispersion diameter)
As a measuring method, a TEM photograph and a Luzex analysis method are used.

  The dispersion diameter of the release agent in the toner particles is calculated as the number average value of the horizontal ferret diameters of the release agent dispersion particles in the toner cross section.

  In addition, the ferret horizontal diameter of the particle | grains used by this invention represents the maximum length in arbitrary one directions of each particle | grain in the some particle | grains image | photographed with the said electron microscope. The maximum length means a distance between parallel lines in the case where two parallel lines that are perpendicular to the one arbitrary direction and are in contact with the outer diameter of the particle are drawn.

  A method for preparing a toner cross-section sample is a method in which a toner is sufficiently dispersed in a room temperature curable acrylic resin, embedded and cured, and then a flaky sample is cut out using a microtome having diamond teeth. The toner cross section was photographed with a transmission electron microscope JEM-2000FX (manufactured by JEOL Ltd.) at an acceleration voltage of 80 kV at a magnification of 30000 times, and a photographic image was captured by a scanner. Release agent in which the horizontal ferret diameter of the release agent dispersed in the toner binder resin is within 0.5 μm from the toner particle surface, and the release agent is outside the above range. Each was measured.

  The term “present within 0.5 μm from the toner particle surface” refers to a state in which 50% or more of the release agent dispersed particles are present within 0.5 μm from the toner particle surface on the basis of the cross-sectional area in the toner cross-sectional photograph.

  The dispersion diameter of the release agent existing within 0.5 μm from the toner surface in one toner particle is measured at 80% or more of the release agent dispersion particles observed on the cross section of the toner, and the number average value is calculated. Further, the average value of 100 toners of the number average value was taken as Ws.

  Similarly, for the dispersion diameter of the release agent existing outside the above range, the number average value of 80% or more of the release agent dispersed particles observed in the cross section of one toner particle is calculated, and further the average value of 100 toners Wc was taken as Wc.

The standard deviation was calculated using the following formula.
Standard deviation (SD) = √ ((measured value−number average value) ² sum / number of data)
That is, the standard deviation S.I. D. (Ws) was calculated by substituting the value of Ws into the above equation. Here, the number average value is the value of Ws, and the number of data is the total number of data used to determine Ws.

  In a similar manner, the standard deviation S.I. D. (Wc) was calculated. The number average value is the value of Wc, and the number of data is the total number of data used to determine Wc.

  In addition, the preferable range of Ws is 100-500 nm, More preferably, it is 150-300 nm. Moreover, the preferable range of Wc is 300 nm-2 micrometers, More preferably, it is 450 nm-1.5 micrometers.

  Furthermore, the range of Wc / Ws is preferably 1.5 to 5, and more preferably 2 to 4. The reason for this is that it is possible to sufficiently exhibit the releasability even during low-temperature fixing and to prevent the release agent from being exposed.

〔Release agent〕
Next, the release agent (hereinafter referred to as wax) according to the present invention will be described.

  First, polar wax is a phenyl group, naphthyl group, heterocyclic group, carboxyl group, ester group, ether group, hydroxyl group, amide group, imide group, nitro group, amino group, ammonium group, sulfonyl group, thiol group as polar groups. , Having a structure having at least one selected from sulfide groups.

  Specific examples of the polar wax according to the present invention include wax oxide obtained by air oxidation of petroleum wax or Fischer Tropsch wax, petroleum wax, α-olefin wax having a double bond at the terminal, Fischer Tropsch An alcohol type wax obtained by air oxidation of any of the waxes in the presence of boric acid, a urethane wax obtained by reacting the alcohol type wax with tolylene diisocyanate, stearic acid or an acid component of behenic acid and stearyl alcohol, behenyl alcohol, It is obtained by removing the low melting point components of ester wax, rice bran wax or carnauba wax obtained by reacting with any alcohol component of 1,4-butanediol with a solvent treatment or a flow-down or centrifugal thin-film distillation apparatus. Ester wax Examples include ketone wax obtained by decarboxylating stearic acid at high temperature under a metal oxide catalyst, and 3-pentadecylphenoxyacetic acid obtained by reacting chloroacetic acid with 3-pentadecylphenol, which is a hydrogenated product of cashew nut oil. . Other examples include fatty acid waxes having 12 to 24 carbon atoms and ester compounds thereof, higher alcohol waxes, lanolin synthetic waxes, carnauba wax, rice wax, beeswax, scale insect wax, and montan wax.

  Specific examples of the nonpolar wax according to the present invention include petroleum wax, low molecular weight polyethylene wax, and low molecular weight polypropylene wax. Furthermore, the compound whose mixing composition ratio of polar wax and nonpolar wax is 0 to 1/20. The nonpolar wax is preferably an alkene or alkane which may have a substituent, and the acid value of the wax is 0 to 0.1 mgKOH / g.

  The endothermic peak (melting point) in DSC is preferably 60 to 110 ° C. for both polar and nonpolar waxes. A wax having a melting point of less than 60 ° C. is liable to cause thermal aggregation when blended with a toner and has a problem in storage stability. On the other hand, a wax such as polypropylene or polyethylene having a melting point exceeding 110 ° C. is not preferable because it requires a large amount of energy for melting the toner at the time of fixing and goes against energy saving.

  As a specific measuring apparatus for DSC, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer) and a TAC7 / DX thermal analyzer controller (manufactured by PerkinElmer) can be used.

  As a measurement procedure, toner 4.5 mg to 5.0 mg is precisely weighed to two decimal places, sealed in an aluminum pan (KITNO.0219-0041), and set in a DSC-7 sample holder. The reference used an empty aluminum pan. The measurement conditions were a measurement temperature of 0 ° C. to 200 ° C., a temperature increase rate of 10 ° C./min, a temperature decrease rate of 10 ° C./min, and heat-cool-heat temperature control. Analysis was performed based on the data in Heat.

  The release agent melting point indicates the peak top temperature of the release agent endothermic peak as the release agent melting point.

  The phrase “having a polar release agent as a main component” means that the ratio of the polar release agent is 80% by mass or more among all the release agents.

  The wax in the core toner may be polar or nonpolar, and the addition amount is 1 to 40% by mass, preferably 5 to 25% by mass.

  On the other hand, the wax in the shell is preferably a polar wax in order to improve the adhesion to paper, and the addition amount is 1 to 50% by mass, preferably 5 to 40% by mass.

[Configuration of toner]
Next, compounds (binder resin, colorant, charge control agent, external additive, lubricant) other than the release agent constituting the toner particles according to the present invention will be described.

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

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

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

  Furthermore, in order to adjust the molecular weight of the resin, a generally used chain transfer agent can be used. The chain transfer agent to be used is not particularly limited. For example, mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, and styrene dimer are used.

  The polymerizable monomer can be polymerized using a radical polymerization initiator. Examples of the radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, 4,4′-azobis-4-cyanovaleric acid and salts thereof, 2,2′-azobis (2-amidinopropane) salt, and the like. And azo compounds and peroxide compounds. Furthermore, you may use the said radical polymerization initiator as a redox-type initiator combined with the reducing agent as needed.

(Coloring agent)
As the colorant used in the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

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

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

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the colorant for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  These colorants may be used alone or in combination of two or more as required. The addition amount of the colorant is set in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner particles.

(Charge control agent)
A charge control agent can be added to the toner particles according to the present invention as necessary. As the charge control agent, known compounds can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid Examples thereof include a metal salt or a metal complex thereof. Examples of the metal contained include Al, B, Ti, Fe, Co, and Ni. Particularly preferred as the charge control agent is a metal complex compound of a benzylic acid derivative. In addition, when the charge control agent has a content of preferably 0.1 to 20.0% by mass with respect to the whole toner particles, good results can be obtained.

(External additive)
The toner particles according to the present invention are preferably prepared by adding an external additive.

  Known external fine particles, organic fine particles, and lubricants can be used as the external additive.

  A conventionally well-known thing can be used as an inorganic fine particle. Specifically, inorganic oxides such as silica, titania and alumina, and doped materials such as titanium-doped silica can be preferably used. These inorganic fine particles may be hydrophobized if necessary.

  Specific examples of the silica fine particles include commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H- manufactured by Hoechst. 200, commercial products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.

  As titania fine particles, for example, commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

As the organic fine particles, specifically, homopolymers such as styrene and methyl methacrylate and copolymers thereof can be used.
Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The addition amount of these external additives is preferably 0.1 to 10.0% by mass with respect to the whole toner particles.

[Toner Production Method]
The toner manufacturing method of the present invention is not particularly limited as long as the relationship of the release agent dispersion diameter is Wc> Ws, but the design is different from the resin particles for the core (core toner) and the resin particles for the shell. A method of producing a polymerization / aggregation type toner that can employ the above resin particles is preferable. As described above, the preferred method for producing the core resin particles is the mini-emulsion polymerization method, and the preferred method for producing the shell resin particles is the wax seed polymerization method.
Specifically, a toner production method using miniemulsion polymer particles as core resin particles and wax seed polymer particles as shell resin particles will be described below.

(Core resin particles)
In miniemulsion polymerization, which is a preferred example of the polymerization step for preparing the core resin particles containing a release agent, the release agent is contained in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less. Add a radically polymerizable monomer solution that is dissolved or dispersed, add mechanical energy to form droplets, and then advance the polymerization reaction in the droplets by radicals from a water-soluble radical polymerization initiator. . As the surfactant to be added to the aqueous medium, an anionic surfactant or a nonionic surfactant can be used, and these may be added singly or in an appropriate composition. In such a polymerization process, forcible emulsification (formation of droplets) by applying mechanical energy is essential. Examples of the means for applying mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and manton gorin. The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, and for example, a range of 50 ° C. to 90 ° C. is used. By this polymerization step, core resin particles containing a release agent are obtained. The dispersion diameter and particle size distribution of the release agent in the core resin particles can be controlled by the amount of surfactant, energy to be applied, and dispersion time.

  Further, following the above-described miniemulsion polymerization step, composite resin particles by multi-stage polymerization in which a polymerization initiator and a polymerizable monomer are newly added to advance the polymerization reaction can also be used.

(Resin particles for shell)
In a preferred seed polymerization method for preparing shell resin particles containing a release agent, a release agent is added to an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less, and mechanical energy is added. Thus, after the release agent is dispersed, and then the radical polymerization initiator is added, the polymerization can be allowed to proceed using the release agent as a seed by adding a polymerizable monomer. As the mold release agent, it is preferable to use a polar mold release agent in order to improve the adhesion to paper.

  In the seed polymerization method, the dispersion diameter and particle size distribution of the release agent can be controlled by the dispersing device, the type and amount of the surfactant, and the dispersion energy and time to be applied. For example, when a homomixer is used, the dispersion diameter of the release agent emulsion can be easily controlled by adjusting the number of rotations. In addition, if the stirring time is too short, the size of each emulsion varies and a uniform particle size distribution cannot be obtained. Therefore, it is preferable to take a long stirring time.

(Coloring agent)
The colorant fine particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. As the surfactant to be used, anionic surfactants and nonionic surfactants can be used, and these may be used alone or mixed in an appropriate composition. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a pressure disperser such as a mechanical homogenizer or a pressure homogenizer, a medium disperser such as a sand grinder or a diamond fine mill. Can be mentioned.

(Aggregation / fusion process)
As a preferred method of aggregating and fusing the core resin particles, colorant fine particles and the like containing a release agent to form the core toner particles, an aqueous medium in which the core resin particles and the colorant fine particles are present is used. In addition, a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like is added as a flocculant having a critical aggregation concentration or higher, and then aggregated by heating and stirring at a temperature higher than the glass transition point Tg of the core resin particles. The particle size growth reaction is performed, and when the predetermined particle size is reached, the particle size growth reaction is stopped, and further, as the aging process, heating and stirring are continued at a temperature higher than the glass transition point Tg of the core resin particles, Examples thereof include a method in which fusion between particles proceeds. By this step, core toner particles containing a core resin, a release agent, and a colorant can be obtained.

  Examples of the salting-out agent used here include alkali metal salts and alkaline earth metal salts. Examples of the alkali metal include monovalent metals such as lithium, potassium and sodium, and examples of the alkaline earth metal include magnesium, calcium, A divalent metal such as strontium or barium can be used, and a divalent or higher salt such as aluminum can also be used. Preferably, potassium, sodium, magnesium, calcium, barium and the like can be mentioned. Examples of constituents of the salt include chlorine salts, bromine salts, iodine salts, carbonates and sulfates.

  Further, in the ripening process, fluidization of the resin occurs in the toner particles, the release agents come into contact with each other to easily form a domain, and the release agent dispersion diameter and the particle size distribution in the toner particles can be changed. Factors that control the domain formation of the release agent accompanying the fluidization of the resin in the aging process include the melting point of the release agent and the thermal energy applied during aging. For example, when the thermal energy applied at the time of aging is increased, the domain formation of the release agent is progressed by increasing the domain size of the release agent, and at the same time, the uniformity of the particle size distribution can be improved.

(Shelling process)
Next, by adding shell resin particles containing a release agent to the dispersion liquid of the core toner particles obtained in the above-described aggregation / fusion process, the shell resin particles are adhered and fused to the core toner particles. Done. In addition, when the added resin particles are adhered to the surface of the core toner particles, a coagulant having the same or larger valence (strong cohesive force) as the coagulant used when forming the core toner particles is further added. Thus, it is possible to improve the adhesion rate. Examples of the flocculant having a large valence include trivalent aluminum salts and tetravalent polyaluminum chloride.

(Filtering and washing process)
The filtration / washing step removes the surfactant and salting-out agent coexisting from the filtered toner particles filtered from the toner particle dispersion obtained in the above step and the filtered toner particles. The cleaning process is performed. Examples of the filtration method include, but are not limited to, a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like.

(Drying process)
The drying step is a step of drying the toner particles that have been washed. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers A stirring dryer or the like is preferably used. The water content of the dried toner particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment are aggregated with a weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill or a Henschel mixer can be used.

[External addition process]
In this process, an external additive is mixed with the dried toner particles as necessary to produce a toner. As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

(Developer)
The toner according to the present invention can be used as a one-component developer or a two-component developer.

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

  Further, it can be mixed with a carrier and used as a two-component developer. As the carrier, conventionally known magnetic particles such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The particle diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm.

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

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

(Image forming device)
As the image forming apparatus, an image forming apparatus having a low-temperature fixing design as a fixing device and having a high printing speed is preferably used. A fixing device with a low temperature fixing design preferably has a fixing temperature of less than 160 ° C. The printing speed is preferably 300 mm / sec or more. This is because the effect of the toner of the present invention is remarkably effective as compared with the conventional product at the fixing device temperature and the printing speed.

  Next, embodiments of the present invention and characteristics thereof will be described to explain the present invention. However, of course, the embodiments of the present invention are not limited to these.

[Toner preparation]
(Example 1)
(Manufacture of resin fine particle 1 for core)
A reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introduction device was charged with 4 g of sodium polyoxyethylene (2) dodecyl ether sulfate and 3000 g of ion-exchanged water, and the internal temperature was kept at 80 ° C. while stirring under a nitrogen stream. The temperature was raised to. After heating, 10 g of potassium persulfate dissolved in 400 g of ion-exchanged water was added to obtain a liquid temperature of 75 ° C., the following monomer mixture was added dropwise over 1 hour, and then heated at 75 ° C. for 2 hours. Polymerization was performed by stirring to prepare resin fine particles. This is referred to as “resin fine particles (A)”.

Styrene 532g
200g of n-butyl acrylate
Methacrylic acid 68g
n-Octyl mercaptan 16g
Second stage polymerization (mini emulsion polymerization)
A reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device was charged with a solution of 3.0 g of polyoxyethylene (2) sodium dodecyl ether sulfate dissolved in 3060 g of ion-exchanged water and heated to 80 ° C. , 35 g of the above-mentioned “resin fine particles (A)”, a solution in which a wax as a release agent and the following monomer solution are dissolved at 80 ° C. are added, and a mechanical disperser having a circulation path “ “Clea mix” (manufactured by M Technique) was mixed and dispersed for 30 minutes to prepare a dispersion containing emulsified particles (oil droplets).

100g of styrene
62 g of n-butyl acrylate
Methacrylic acid 12g
n-octyl mercaptan 1.75 g
96 g of paraffin wax “HNP-57” (manufactured by Nippon Seiki)
Next, an initiator solution in which 5 g of potassium persulfate is dissolved in 100 g of ion-exchanged water is added to this dispersion, and this system is heated and stirred at 80 ° C. for 1 hour to carry out miniemulsion polymerization. Obtained.

Third stage polymerization Further, a solution prepared by dissolving 5.45 g of potassium persulfate in 220 g of ion-exchanged water was added, and 294 g of styrene under a temperature condition of 80 ° C
155 g of n-butyl acrylate
n-octyl mercaptan 7.08 g
A monomer mixture consisting of was added dropwise over 1 hour. After completion of the dropping, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain resin fine particles. The obtained resin fine particle dispersion is referred to as “core resin fine particle 1”.

(Manufacture of resin fine particles 1 for shell) (Wax seed polymerization)
A round stainless steel reactor was charged with 4.0 g of sodium polyoxyethylene (2) dodecyl ether sulfate, 450 g of ion-exchanged water, and 25 g of wax behenate behylate as a release agent, and an ultrasonic homogenizer US-150T (Nippon Seiki) For 5 hours to obtain “Wax Dispersion 1”.

  Next, 350 g of ion-exchanged water and 450 g of “Wax Dispersion 1” were added to a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction device, and the internal temperature was raised to 80 ° C. while stirring under a nitrogen stream. I let you. Subsequently, after adding 1.30 g of potassium persulfate dissolved in 65 g of ion-exchanged water, the following monomer mixture was added dropwise over 2 hours, followed by heating and stirring at 80 ° C. for 2 hours. Wax seed polymerization was performed to prepare resin fine particles.

Styrene 71.4g
2-Ethylhexyl acrylate 20.3g
Methacrylic acid 12.5g
n-Octylmercaptan 1.37g
This is designated as “shell fine resin particle 1”.

(Preparation of colorant dispersion)
90 g of sodium dodecyl sulfate was dissolved in 1600 g of ion-exchanged water with stirring. While stirring this solution, 420 g of carbon black “Regal 330R” (manufactured by Cabot Corp.) is gradually added, and then dispersed by using a stirrer “Claremix” (manufactured by M Technique Co., Ltd.). A dispersion of agent particles was prepared. This is designated as “colorant dispersion 1”.

  The particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.) and found to be 110 nm.

(Aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 392 g of “core resin fine particles 1” in terms of solid content, 1100 g of ion-exchanged water, and 200 g of “colorant dispersion 1” were charged. After adjusting the liquid temperature to 30 ° C., the pH was adjusted to 10 by adding a 5 mol / liter sodium hydroxide aqueous solution.

  Next, an aqueous solution in which 60 g of magnesium chloride was dissolved in 60 g of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After holding for 3 minutes, the temperature was raised, and the system was heated to 80 ° C. over 60 minutes, and the particle growth reaction was continued while maintaining 80 ° C. In this state, the particle size of the associated particles was measured with “Coulter Multisizer III”, and when the median diameter on the volume basis reached 6 μm, an aqueous solution in which 40 g of sodium chloride was dissolved in 160 g of ion-exchanged water was added. Particle growth was stopped, and further, as a ripening process, fusion between the particles was advanced by heating and stirring at a liquid temperature of 80 ° C. for 1 hour to form “core part 1”.

(Shelling process)
Next, 44 g of “shell layer resin fine particles 1” is added in terms of solid content, and stirring is continued at 80 ° C. for 1 hour. The particles of “shell layer resin fine particles 1” are placed on the surface of “core part 1”. A shell layer was formed by fusing. Here, an aqueous solution dissolved in 150 g of sodium chloride and 600 g of ion-exchanged water was added to perform an aging treatment, and when the desired circularity was reached, the solution was cooled to 30 ° C.

(Solid-liquid separation and washing process)
The produced particles were subjected to solid-liquid separation with a basket-type centrifuge “MARK III model number 60 × 40” (manufactured by Matsumoto Kikai Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with ion-exchanged water at 40 ° C. until the electric conductivity of the filtrate reached 5 μS / cm using the basket type centrifuge.

(Drying process)
Thereafter, it was transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content became 0.5 mass% to prepare “Toner Bk Particles 1”.

(External additive addition process)
1% by mass of hydrophobic silica (number average primary particle size = 12 nm) was added to the “toner Bk particles 1” obtained above and mixed with a Henschel mixer to prepare “toner Bk1”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk1”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Example 2)
(Manufacture of resin fine particles 2 for core)
In the example of “core resin fine particles 1”, the mixing and dispersing time by a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path for the second stage polymerization was changed from 30 minutes to 45 minutes. In the same manner, “core resin fine particles 2” were obtained.

(Manufacture of resin fine particles 2 for shell)
In the example of “resin fine particles for shell 1”, the “wax dispersion 2” is the same as that in the example except that the dispersion time in the ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho) is changed from 5 hours to 4 hours. Got. Next, polymerization was carried out in the same manner to prepare resin fine particles. This is designated as “resin fine particles 2 for shell”.

(Toner preparation)
In Example 1 (aggregation / fusion process), “core resin fine particle 1” is changed to “core resin fine particle 2”, and “shell resin fine particle 1” in (shelling process) is changed to “shell resin fine particle 1”. The “Toner Bk2” was produced in the same manner as in “2” except that the process was performed up to (addition step of external additive).

(Partition agent dispersion diameter)
For the obtained “Toner Bk2”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Example 3)
(Manufacture of resin fine particles 3 for shell)
In the example of “resin fine particles for shell 1”, the same procedure was followed except that the dispersion time in the ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho) was changed from 5 hours to 2.5 hours. 3 "was obtained. Next, polymerization was carried out in the same manner to prepare resin fine particles. This is designated as “resin fine particles 3 for shell”.

(Toner preparation)
In Example 1 (aggregation / fusion process), “core resin fine particle 1” is changed to “core resin fine particle 2”, and “shell resin fine particle 1” in (shelling process) is changed to “shell resin fine particle 1”. Except for the change to “3”, the same procedure was followed until (External additive addition step) to produce “Toner Bk3”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk3”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

Example 4
(Manufacture of resin fine particles 3 for core)
In the example of “core resin fine particles 1”, the mixing and dispersing time by a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path of the second stage polymerization was changed from 30 minutes to 15 minutes. In the same manner, “core resin fine particles 3” were obtained.

(Manufacture of resin fine particles 4 for shell)
In the example of “resin fine particles for shell 1”, the amount of sodium polyoxyethylene (2) dodecyl ether sulfate was changed from 4.0 g to 5.0 g, and an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho) was used. A “wax dispersion 4” was obtained in the same manner except that the dispersion time was changed from 5 hours to 6 hours. Next, polymerization was carried out in the same manner to prepare resin fine particles. This is designated as “shell resin fine particles 4”.

(Toner preparation)
In Example 1 (aggregation / fusion process), “core resin fine particle 1” is changed to “core resin fine particle 3”, and “shell resin fine particle 1” in (shelling process) is changed to “resin fine particle for shell”. A “toner Bk4” was produced in the same manner as described above except that the process was changed to “4”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk4”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Example 5)
(Manufacture of resin fine particles 4 for core)
In the example of “core resin fine particles 1”, the mixing and dispersing time by a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path for the second stage polymerization was changed from 30 minutes to 90 minutes. In the same manner, “core resin fine particles 4” were obtained.

(Manufacture of resin fine particles 5 for shell)
In the example of “resin fine particles for shell 1”, the amount of sodium polyoxyethylene (2) dodecyl ether sulfate was changed from 4.0 g to 5.0 g, and an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho) was used. A “wax dispersion 5” was obtained in the same manner except that the dispersion time was changed from 5 hours to 8 hours. Next, polymerization was carried out in the same manner to prepare resin fine particles. This is designated as “shell fine resin particle 5”.

(Toner preparation)
In the (aggregation / fusion process) of Example 1, “core resin fine particle 1” is changed to “core resin fine particle 4”, and “shell resin fine particle 1” in (shelling process) is changed to “shell resin fine particle”. Except for the change to “5”, the same procedure was followed until (External additive addition step) to produce “Toner Bk5”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk5”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Example 6)
(Manufacture of resin fine particles 5 for core)
In the example of “core resin fine particle 1”, the amount of sodium polyoxyethylene (2) dodecyl ether sulfate in the second stage polymerization was changed from 3.0 g to 1.5 g, and a mechanical disperser having a circulation path “ “Core resin fine particles 5” were obtained in the same manner except that the mixing and dispersing time by “CLEAMIX” (manufactured by M Technique Co., Ltd.) was changed from 30 minutes to 10 minutes.

(Manufacture of resin fine particles 6 for shell)
In the example of “resin fine particles for shell 1”, the same procedure was followed except that the dispersion time in the ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho) was changed from 5 hours to 4.5 hours. 6 ”was obtained. Next, polymerization was carried out in the same manner to prepare resin fine particles. This is designated as “shell resin fine particles 6”.

(Toner preparation)
In the (aggregation / fusion process) of Example 1, “core resin fine particle 1” is changed to “core resin fine particle 5”, and “shell resin fine particle 1” in (shelling process) is changed to “resin fine particle for shell”. Except for the change to “6”, the same procedure was followed until (External additive addition step) to produce “Toner Bk6”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk6”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Comparative Example 1)
(Manufacture of resin fine particles 6 for core)
In a round stainless steel reactor, 8.0 g of sodium polyoxyethylene (2) dodecyl ether sulfate, 450 g of ion-exchanged water, and 50 g of wax behenate, which is a mold release agent, were charged, and an ultrasonic homogenizer US-150T (Nippon Seiki) For 5 hours to obtain “Wax Dispersion 7”.
Next, 1280 g of ion-exchanged water and 450 g of “Wax Dispersion 7” were added to a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction device, and the internal temperature was raised to 80 ° C. while stirring under a nitrogen stream. I let you. Subsequently, after adding 1.30 g of potassium persulfate dissolved in 65 g of ion-exchanged water, the following monomer mixture was added dropwise over 2 hours, followed by heating and stirring at 80 ° C. for 2 hours. Wax seed polymerization was performed to prepare resin fine particles.

Styrene 231.5g
n-Butyl acrylate 127.4g
Methacrylic acid 7.0g
n-octyl mercaptan 5.31 g
This is designated as “core resin fine particle 6”.

(Toner preparation)
In the (aggregation / fusion process) of Example 1, “core resin fine particle 1” is changed to “core resin fine particle 6”, and “shell resin fine particle 1” in (shelling process) is changed to “shell resin fine particle”. Except for the change to “6”, the same procedure was followed until (External additive addition step) to produce “Toner Bk7”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk7”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Comparative Example 2)
(Manufacture of resin fine particles 7 for shell)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introducing device, 4.0 g of sodium polyoxyethylene (2) dodecyl ether sulfate and 3000 g of ion-exchanged water were charged, and the internal temperature was increased while stirring under a nitrogen stream. The temperature was raised to 80 ° C. After heating, 10 g of potassium persulfate dissolved in 400 g of ion-exchanged water was added, and the following monomer mixture was added dropwise over 2 hours, followed by heating and stirring at 80 ° C. for 2 hours for emulsion polymerization. The resin fine particles were prepared.

Styrene 571.2g
2-ethylhexyl acrylate 162.4 g
Methacrylic acid 100.0 g
n-octyl mercaptan 10.96 g
This is designated as “shell fine resin particle 7”.

(Toner preparation)
In Example 1 (aggregation / fusion process), “core resin fine particle 1” is changed to “core resin fine particle 3”, and “shell resin fine particle 1” in (shelling process) is changed to “resin fine particle for shell”. A “toner Bk8” was produced in the same manner as described above except that the process was changed to “7”.

(Partition agent dispersion diameter)
For the obtained “Toner Bk8”, the dispersion diameter of the release agent was measured, and Wc, Ws, and S.P. D. (Wc), S.M. D. (Ws) was calculated. Table 1 shows.

(Development of developer)
Developer toners 1 to 8 having a toner concentration of 6% were prepared by mixing each of “Toner Bk particles 1 to 8” with a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin.

(Image evaluation)
Using the above developers 1 to 8, a commercially available digital copying machine bizhub Pro 1050 was used as an evaluation machine, and a modified fixing device was used. (Fixing temperature 140 ° C., printing speed 300 mm / sec) ◎ to Δ are acceptable levels, and x is unacceptable.

(Low temperature fixability)
The surface temperature (measured at the center of the roller) of the fixing heat roller of the evaluator is changed in increments of 5 ° C. within a range of 120 to 170 ° C., and the direction perpendicular to the conveying direction at each surface temperature. The A4 image having a solid black belt image having a width of 5 mm is conveyed and fixed by vertical feeding, and then the A4 image having a solid black belt image having a width of 5 mm and a halftone image having a width of 20 mm is laterally fed perpendicularly to the conveyance direction. The temperature when the image was smeared due to the conveyance offset was measured and judged according to the following evaluation criteria.

A: The minimum fixing temperature was less than 130 ° C. ○: The minimum fixing temperature was 130 ° C. or more and less than 145 ° C. Δ: The minimum fixing temperature was 145 ° C. or more and less than 160 ° C. ×: The minimum fixing temperature was 160 ° C. It was above (winding evaluation)
An image when the surface temperature of the fixing heat roller is fixed at 150 ° C., and an A4 image having a solid black belt-like image having a width of 5 cm in the direction perpendicular to the conveyance direction is conveyed by vertical feeding at each surface temperature. The separation property between the fixing roller on the side and the paper was determined according to the following evaluation criteria.

◎: Paper does not curl and separates from fixing roller without touching separation claw ○: Paper separates from fixing roller and separation claw, but there is no trace of separation claw on image △: Paper separates from fixing roller Separation with nail, but trace of separation nail on image is hardly noticeable ×: Paper is separated with fixing roller and separation nail, separation nail trace remains on image or wraps around fixing roller and cannot be separated from fixing roller (Evaluation of black spots and white stripes)
The toners prepared above were loaded in order and printed in an environment of 20 ° C. and 55% RH. The print is an A4 size fine paper (64 g / m ² ) of an image with a pixel rate of 10% (original image with character image 7%, human face photo, solid white image, solid black image each 1/4). ) And 10,000 images, and the determination was made based on the 10,000th image.

  Large items such as streak-like image defects (white streaks) caused by filming were visually determined. The criteria for determining black spots and streak-like image defects are as follows.

◎: 1 black spot or less and no streak defect / A4 paper / good ○: 2 to 3 black spots / A4 paper and no streak △: 2 to 3 black spots / A4 paper The extent to which the density is slightly thinned on one sheet and a solid black image x 4 or more black spots, or a clearly noticeable white streak-like image defect can be confirmed

Claims (6)

In an electrostatic latent image developing toner containing at least a binder resin and a release agent, a release agent dispersion diameter Ws (nm) existing within 0.5 μm from the toner surface, and a release agent existing outside the above range The relationship with the dispersion diameter Wc (nm) is Wc> Ws
However, the toner for developing an electrostatic latent image, wherein Ws ≧ 50 nm. The electrostatic latent image developing toner according to claim 1, wherein 1.5 ≦ Wc / Ws ≦ 5. The electrostatic latent image developing toner according to claim 1, wherein the release agent for forming Ws contains a polar release agent as a main component. Standard deviation of the dispersion diameter of the release agent forming Ws D. (Ws) is 15 or more and less than 150, and the standard deviation S.D. of the dispersion diameter of the release agent that forms Wc. D. 4. The toner for developing an electrostatic latent image according to claim 1, wherein (Wc) is 20 or more and less than 250. 5. 5. The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the surface of the core toner containing a resin fine particle containing a release agent and a pigment produced by a miniemulsion polymerization method is separated from the surface of the core toner. A method for producing a toner for developing an electrostatic latent image, comprising: adhering and fusing polymer particles obtained by adding a polymerizable monomer in the presence of mold agent particles and polymerizing them. 6. An image forming method using the toner according to claim 1, wherein a printing speed is 300 mm / sec or more.