JP5729038B2 - Manufacturing method of core-shell type toner - Google Patents

Description

The present invention relates to a core-shell type toner manufacturing how.

  Various methods are currently known as electrophotographic image forming methods, all of which include a step (exposure step) of forming an electrical latent image on a photoconductor using a photoconductive substance, and the latent image. A developing step of developing the toner with toner. Thereafter, generally, a transfer process for transferring a toner image onto a transfer material (recording medium) such as paper and a fixing process for fixing the toner image by heat using a fixing rotor or the like are provided.

  The toner used in the electrophotographic method as described above is usually composed of toner particles containing a resin component and a colorant as main components.

  Furthermore, today, toner particles are added to the particle surface with fine particles such as silica, alumina, and titania as external additives with almost no exception. The external additives impart fluidity to the toner and control the chargeability of the toner. In addition, it has been added in the final step of toner production (for example, Patent Document 1).

  Such an external additive is generally externally added by mixing with toner particles using a Henschel mixer used as a powder mixer or a hybridizer used as a surface modifier. However, the toner to which the external additive is applied by such a method cannot fully exhibit the function of the external additive.

  That is, even when the toner particles and the external additive are mixed using the above-described mixer, the amount of the external additive attached to the toner particles is insufficient, or the external particles once attached to the toner particles The additive is also easily detached from the toner particles and is difficult to remain on the surface of the toner particles.

  As described above, the external additive not attached to the toner particles and the external additive detached from the toner particles are present as free external additives in the toner. Free external additives tend to form aggregates. Such agglomerates cause problems such as contamination of the inside of the developing apparatus and scratching of the surface of the member in contact with the toner, resulting in deterioration of the image quality of the formed toner image. Also, in order to make the adhesion amount of the external additive to the toner particles sufficient, if the mixing time is extended or a greater shear force is applied, the toner particles are deformed, broken, etc. There was a problem that problems such as easy aggregation occurred.

  Further, in the mixing method as described above, the external additive is segregated in a part near the surface of the toner particles, and it is difficult to uniformly attach the external additive to the surface of the toner particles.

  In order to solve such problems, a method of adding silica at the time of toner production aggregation is known (see Patent Document 2). However, this method causes agglomeration of silica particles, which causes a problem in image quality. .

JP 2000-137348 A JP 2008-89919 A

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

That is, the object of the present invention is that the inorganic fine particles are uniformly present on the surface of the toner particles, the detachment of the external additive can be suppressed, the contamination of the carrier can be prevented, and there is no variation in the charge amount. it is to provide a core-shell type toner manufacturing how that can be prevented.

  As a result of intensive studies by the inventor of the present invention, it has been found that the object of the present invention can be achieved by adopting the following invention configuration.

(1)
A method for producing a core-shell type toner, which is produced through at least the following steps 1 to 4.

1: Step of producing core particles of core-shell toner 2: Step of dispersing inorganic fine particles in a monomer and dispersing this in an aqueous surfactant solution 3: Step of polymerizing the monomer to produce resin particles for a shell layer 4: A step of coating the surface of the core particles with resin particles for a shell layer to form a shell layer (2)
The method for producing a core-shell toner according to (1), wherein the inorganic fine particles are silica particles having a number average particle diameter of 5 nm to 200 nm.

(3)
The method for producing a core-shell toner according to (1) or (2), wherein the inorganic fine particles are fumed silica that is not subjected to a hydrophobic treatment .

(4)
The weight average molecular weight (Mw) of the binder resin contained in the resin particles for the shell layer is 10,000 or more and 100,000 or less, any one of (1) to (3), Of manufacturing a core-shell toner.

According to the present invention, inorganic fine particles are uniformly present on the surface of the toner particles, the detachment of the external additive is suppressed, carrier contamination can be prevented, and there is no variation in the charge amount, thereby preventing toner scattering. it is possible to provide a core-shell type toner manufacturing how that can.

FIG. 3 is a schematic cross-sectional view of the core-shell type toner of the present invention. 1 is a schematic cross-sectional view of an example image forming apparatus according to the present invention.

  The present invention will be described in more detail.

  In the present invention, the inorganic fine particles are dispersed in the monomer before the polymerization of the binder resin for the shell layer of the core-shell type toner. Therefore, the inorganic fine particles are held in the binder resin in a uniformly dispersed state without aggregation. The FIG. 1 is a cross-sectional view schematically showing a core-shell type toner of the present invention. Inorganic fine particles 3 are evenly dispersed in the shell layer 2 covering the surface of the core particles 4 of the core-shell toner 1.

  By coating the core particle surface with the binder resin for the shell layer in this way, the inorganic fine particles can be uniformly dispersed in the shell layer. Since these inorganic fine particles function in the same manner as the external additive, it is considered that the charge amount distribution during toner charging becomes sharp and scattering during image formation is suppressed to improve image quality. In addition, since the inorganic fine particles are firmly held in the resin, it is unlikely to be detached from the toner surface, so that carrier contamination is unlikely to occur. As a result, the durability of the developer is improved. In particular, it is possible to produce a highly dispersed resin by polymerizing while dropping droplets in which inorganic fine particles are dispersed in a monomer by a disperser.

  It is not known that a remarkable effect can be obtained when inorganic fine particles are contained in the shell layer by such a method. For example, even if forcibly dispersing with a disperser or the like at the time of addition, for example, polymerization is performed. There was a concern that the inorganic fine particles may be combined by separating the resin particles for the shell in the process or the process of coating the core resin particles on the core particles. However, in practice, it has been found that a uniform dispersion state is maintained until the toner shell layer is produced.

  As will be described later, hydrophilizing the surface of the inorganic fine particles is an effective means for stably producing the core-shell toner of the present invention.

[Inorganic fine particles]
The inorganic fine particles in the present invention are those used as normal external additives. Preferably, silica, titania, and alumina are used, and since the surface layer of the toner needs to function as an external additive, the primary average particle diameter is preferably 5 nm or more and 100 nm or less.

  Specifically, as silica fine particles, for example, 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, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.

  Examples of the titanium fine particles include commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercial products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and 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.

  The addition ratio of the inorganic fine particles to the shell resin is often in the range of 0.5 to 50 parts of the inorganic fine particles per 100 parts of the resin mass for the shell, and the amount ratio at which the effect as an external additive of the inorganic fine particles can be emitted. If it is.

  The inorganic fine particle disperser needs to have a shearing force of a certain level or more. If the inorganic fine particles are not stably dispersed, the inorganic fine particles may settle after polymerization, and the effect of the present invention can be reduced. There is sex. Specific examples include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and Manton gorin.

(Measurement of particle size of inorganic fine particles)
The number average primary particle diameter of the inorganic fine particles is specifically measured by the following method.

  A 30,000 times photograph of the toner is taken with a scanning electron microscope, and the photograph image is captured by a scanner. The image processing analyzer LUZEX AP (manufactured by Nireco) binarizes the external additive present on the toner surface of the photographic image, and calculates the horizontal ferret diameter for 100 external additives. The average value is the number average primary particle size.

  In addition, when the inorganic fine particles are obtained as a simple substance, the measurement may be performed with Microtrac UPA150 (Nikkiso Co., Ltd.).

  The measurement method is as follows: 0.5 g of inorganic fine particles are placed in a beaker having a capacity of 100 ml, a few drops of a surfactant are added dropwise, 50 ml of ion exchange water is added, and dispersed for 5 minutes using an ultrasonic homogenizer US-150T. The number average diameter calculated using the apparatus is the number average primary particle diameter of the inorganic fine particles.

  Examples of the inorganic fine particles include silica, titania, zirconia, and alumina whose surface has been subjected to a hydrophilic treatment, and silica is preferred among them. Further, the silica is preferably produced by a wet method. The wet method is not particularly limited, and examples thereof include a precipitation method and a sol-gel method. Silica produced by a wet method has a narrow particle size distribution and a spherical shape close to a true sphere. Further, as a feature of the wet method, since the specific surface area is larger than that obtained by the conventional dry method, the effect of improving the adhesion with the binder resin can be obtained. Further, as a surface treatment method of the inorganic fine particles, fumed silica that is not subjected to a hydrophobizing treatment is preferable.

[Method for producing core-shell toner]
Next, a method for producing a core-shell type toner for electrophotography according to the present invention will be described.

  In the present invention, the weight average particle diameter (dispersed particle diameter) of the resin particles for the shell layer is preferably in the range of 10 to 1000 nm, more preferably in the range of 30 to 300 nm.

  This weight average particle diameter is a value measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  When the toner according to the present invention is manufactured, first, resin particles and colorant particles are associated and fused to produce core particles (hereinafter referred to as core particles). Next, resin particles are added to the core particle dispersion, and the resin particles are aggregated and fused on the surface of the core particles to coat the surface of the core particles to produce colored particles having a core-shell structure. As described above, the toner according to the present invention is prepared by adding resin particles to a core particle dispersion prepared by various manufacturing methods and fusing the resin particles to the core particles.

  In addition, when the shell is formed, the shape of the toner is finally controlled to give an appropriate shape. For that purpose, it is most important to prepare core particles having a uniform shape with uniform particle sizes. is there. With such core particles, resin fine particles forming a shell uniformly adhere to the surface thereof, and as a result, toner particles having a very uniform film thickness can be produced.

  The core particles constituting the toner according to the present invention are produced by a production method in which resin particles and colorant particles are aggregated and fused. The shape of the core particles is controlled, for example, by controlling the heating temperature in the aggregation / fusion process and the heating temperature and time in the first aging process.

  Of these, the time control in the first aging step is the most effective. Since the ripening step is intended to adjust the circularity of the associated particles, the target circularity is reached by controlling this time.

  The core-shell type toner of the present invention is produced through the following steps.

[Process for producing core particles]
(1) Making a solution / dispersion in which a radical polymerizable monomer is dissolved or dispersed (2) Polymerizing the monomer to prepare a dispersion of resin particles (3) Coloring with resin particles in an aqueous medium Aggregation and fusion for agglomerating and fusing agent particles to obtain core particles (association particles) (4) First aging for aging associated particles by heat energy to adjust the shape [disperse inorganic fine particles in monomer, Step of dispersing this in an aqueous surfactant solution]
(5) Disperse inorganic fine particles in a monomer and disperse this in a core particle dispersion that is an aqueous surfactant solution [Step of polymerizing monomer to produce resin particles for shell layer]
(6) Producing the resin particles for the shell layer produced by polymerizing the monomer particles [Process for forming the shell layer by covering the surface of the core particles with the resin particles for the shell layer]
(7) Shelling step for agglomerating and fusing the resin particles for the shell layer on the surface of the core particles to form core-shell structured colored particles (8) Coloring the core-shell structure by aging the core-shell structured colored particles with thermal energy Second ripening step for adjusting the shape of the particles (9) A washing step for solid-liquid separation of the colored particles from the cooled colored particle dispersion and removing the surfactant from the colored particles to obtain toner particles (note that The aggregate of toner particles is called toner)
[Subsequent steps]
(10) Drying step of drying the washed toner particles If necessary, a step of adding an external additive to the dried toner particles may be added after the drying step)
Next, the above steps will be described in detail with respect to typical examples.

[Process for producing core particles]
(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution by dissolving a release agent compound or the like in a radical polymerizable monomer (monomer) as required.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which a wax is dissolved or dispersed in an aqueous medium containing a surfactant having a critical micelle concentration (CMC) or less is added. Then, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to advance the polymerization reaction in the droplets. An oil-soluble polymerization initiator may be contained in the droplet. In such a polymerization process, mechanical energy is imparted and forcedly emulsified (formation of droplets) is essential. Examples of the mechanical energy applying means include strong stirring such as homomixer, ultrasonic wave, and manton gorin or ultrasonic vibration energy applying means.

  By this polymerization step, resin fine particles containing a wax or the like and a binder resin are obtained. Such resin particles may be colored fine particles or fine particles that are not colored (this case has been described in the above description of the process). The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using uncolored resin particles, the dispersion of the colorant particles is added to the dispersion of the resin particles in the aggregation / fusion process described later to melt the resin particles and the colorant particles. Color particles can be obtained by attaching.

(3) Aggregation / fusion process As a method of aggregation and fusion in the fusion process, salting out using resin particles obtained in the polymerization process (adding colorant particles if not colored resin particles) A fusion method is preferred. In the aggregation / fusion process, additive particles such as release agent particles and charge control agents can be aggregated and fused together with resin particles and colorant particles.

  In this case, “salting out / fusion” means that aggregation and fusion are performed in parallel, and when the particles have grown to a desired particle size, an aggregation terminator is added to stop the particle growth. The heating for controlling the particle shape according to the above is performed continuously.

  The “aqueous medium” in the agglomeration / fusion step is one in which the main component (50% by mass or more) is made of water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran.

  The colorant 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. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. Examples thereof include a medium type disperser. In addition, examples of the surfactant used include the same surfactants as described below. The colorant particles may be surface modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  The salting out / fusing method, which is a preferred agglomeration and fusing method, is a salting out method comprising an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like in water in which resin fine particles and colorant fine particles are present. An agent is added as a coagulant having a critical coagulation concentration or higher, and then salting out is advanced by heating to a temperature above the glass transition point of the resin particles and above the melting peak temperature (° C.) of the mixture. At the same time, it is a process of fusing. Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used.

  When agglomeration and fusion are performed by salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible. The reason for this is not clear, but there are problems that the aggregation state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. Occur. The temperature for adding the salting-out agent needs to be at least the glass transition temperature of the resin particles. The reason for this is that if the temperature at which the salting-out agent is added is equal to or higher than the glass transition temperature of the resin particles, the salting-out / fusion of the resin particles proceeds rapidly, but the particle size cannot be controlled. There arises a problem that particles having a particle size are generated. Although the range of this addition temperature should just be below the glass transition temperature of resin, generally it is 5-55 degreeC, Preferably it is 10-45 degreeC.

  Further, the salting-out agent is added at a temperature not higher than the glass transition temperature of the resin fine particles, and then the temperature is raised as quickly as possible to a temperature not lower than the glass transition temperature of the resin fine particles and not lower than the melting peak temperature (° C.) of the mixture. Heat to. The time until this temperature rise is preferably less than 1 hour. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 0.25 ° C./min or more. The upper limit is not particularly clear, but if the temperature is increased instantaneously, salting out proceeds rapidly, so there is a problem that particle size control is difficult, and 5 ° C./min or less is preferable. By this fusing step, a dispersion of associated particles (core particles) formed by salting out / fusing resin fine particles and arbitrary fine particles is obtained.

(4) First aging step In the present invention, by controlling the heating temperature in the aggregation / fusion step, particularly the heating temperature and time in the first aging step, the particle size is constant and the distribution is narrow. The surface of the core particle is controlled so as to have a smooth but uniform shape. Specifically, the heating temperature is lowered in the aggregation / fusion process to suppress the progress of fusion between the resin particles to promote homogenization, the heating temperature is lowered in the first aging process, and the time The surface of the core particles is controlled to have a uniform shape by increasing the length.

[Step of dispersing inorganic fine particles in monomer and dispersing this in aqueous surfactant solution]
(5) Step of dispersing inorganic fine particles in a monomer and dispersing this in a core particle dispersion that is an aqueous surfactant solution The inorganic fine particle disperser must have a shearing force of a certain level, If the inorganic fine particles are not stably dispersed, the inorganic fine particles may be precipitated after polymerization, which may reduce the effect of the present invention. Specific examples include means for applying strong stirring or ultrasonic vibration energy such as homomixer, ultrasonic wave, and Manton gorin.

[Process of coating the surface of the core particles with the resin particles for the shell layer to form the shell layer]
(6) Shelling step In the shelling step, the resin particle dispersion for the shell layer is added to the core particle dispersion to agglomerate and fuse the resin particles for the shell layer to the core particle surface. The resin particles for the shell layer are coated to form colored particles.

  Specifically, the core particle dispersion is added with a dispersion of resin particles for shells while maintaining the temperature in the above-described aggregation / fusion process and the first aging process, and it takes several hours while continuing heating and stirring. Then, the resin particles for shell are slowly coated on the surface of the core particles to form colored particles. The heating and stirring time is preferably 1 hour to 7 hours, particularly preferably 3 hours to 5 hours.

[Process of adjusting final shape of toner]
Second aging step of (7) Shell resin in which a growth agent is stopped by adding a terminator such as sodium chloride at the stage when colored particles have reached a predetermined particle size by shelling, and then adhered to the core particles Heating and stirring are continued for several hours in order to fuse the particles. In the shelling step, a shell having a thickness of 100 to 300 nm is formed on the surface of the core particle. In this way, resin particles are fixed to the surface of the core particles to form a shell, and rounded and colored particles having a uniform shape are formed.

  In the present invention, it is possible to control the shape of the colored particles in the true sphere direction by setting the time of the second aging step longer or by setting the aging temperature higher.

(8) and (9) Cooling Step / Solid-Liquid Separation / Washing Step This step is a step of cooling (rapid cooling) the dispersion of the colored particles. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

  In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the colored particles from the dispersion of colored particles cooled to a predetermined temperature in the above-described step, and a solid-liquid separated toner cake (in a wet state) A cleaning treatment for removing deposits such as a surfactant and a salting-out agent from an aggregate obtained by agglomerating certain colored particles into a cake is performed. Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

[Subsequent steps]
(10) Drying step This step is a step of drying the washed cake to obtain dried colored particles. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less. In addition, when the dried colored particles are aggregated by weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used. The particles thus produced are toner particles.

  The external addition treatment step is a step of mixing an external additive with the dried toner particles as necessary.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

〔toner〕
The toner of the present invention is a core-shell type toner, and it is desirable that the toner has a mass average particle size of 3.0 to 8.0 [mu] m and a uniform particle size distribution. Specifically, the circularity measured by a usual method is 0.940 to 0.98, preferably 0.95 to 0.97. The reason is that it is the same as that of a normal toner, and it is likely that voids are likely to occur at low circularity, and cleaning failure may occur at excessively high circularity.

  The toner shell ratio (shell resin mass / total toner resin mass × 100) is preferably 3 to 20%. This is because if this ratio is too high, the shell resin generally has a high glass transition point (Tg) and a high softening point, which may cause a fixing failure.

  As will be described later, the toner of the present invention can contain a release agent, a charge control agent, and the like that are contained in a normal toner, if necessary.

  The volume-based median diameter of the toner particles is measured using a measuring device in which a computer system equipped with data processing software “Software V3.51” is connected to “Coulter Multisizer 3” (manufactured by Beckman Coulter). Can be calculated.

  The toner particles constituting the toner of the present invention preferably have an average circularity of 0.930 to 1.000, more preferably 0.950 to 0.995, from the viewpoint of improving transfer efficiency.

  The average circularity of the toner particles can be measured using “FPIA-2100” (manufactured by Sysmex). Specifically, the toner (toner particles) is blended with an aqueous solution containing a surfactant, subjected to ultrasonic dispersion treatment for 1 minute to disperse, and then subjected to measurement conditions HPF by “FPIA-2100” (manufactured by Sysmex). In the (high-magnification imaging) mode, photographing is performed at an appropriate density of 3,000 to 10,000 HPF detections, and the circularity of each toner particle is calculated according to the following formula (T). Calculated by adding the degree and dividing by the total number of toner particles.

Formula (T): Average circularity = (peripheral length of a circle having the same projected area as a particle image) / (peripheral length of a particle role image)
[Toner material used in the present invention]
(1) Binder Resin The resin A forming the core particles and the resin B forming the shell layer are preferably styrene-acrylic copolymer resins. Moreover, the monomer which produces resin which forms a core part includes a polymerizable monomer that lowers the glass transition temperature (Tg) of a copolymer such as propyl acrylate, propyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate. Copolymerization is preferred. Moreover, the monomer for producing the resin forming the shell layer is copolymerized with a polymerizable monomer that raises the glass transition temperature (Tg) of a copolymer such as styrene, methyl methacrylate, and methacrylic acid. Is preferred.

  The resin constituting the toner according to the present invention will be described in more detail.

  As the resin used for each of the core and shell structures of the toner according to the present invention, a polymer obtained by polymerizing a polymerizable monomer as described below can be used.

  The resin according to the present invention contains a polymer obtained by polymerizing at least one polymerizable monomer as a constituent component. Examples of the polymerizable monomer 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, p Styrene or styrene derivatives such as -n-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, methacryl N-butyl acid, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, Methacrylate derivatives such as n-octyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, acrylic Acrylate derivatives such as isopropyl acid, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, Olefins such as ethylene, propylene, isobutylene, halogenated vinyls such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl propionate, vinyl acetate , Vinyl esters such as vinyl benzoate, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone, N-vinyl carbazole, N-vinyl indole, N There are N-vinyl compounds such as vinylpyrrolidone, vinyl compounds such as vinylnaphthalene and vinylpyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide. These vinyl monomers can be used alone or in combination.

  Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, and 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.

  Furthermore, multifunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.

  The mass average molecular weight (Mw) of the shell resin of the present invention is suitably 10,000 to 100,000.

  In measuring the molecular weight of the resin, the mass average molecular weight (Mw) in terms of standard polystyrene can be measured by gel permeation chromatography (GPC). Specifically, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent. Flow at a flow rate of 0.2 ml / min. Dissolve the domain resin (resin particles from the domain resin) as a measurement sample in tetrahydrofuran to a concentration of 1 mg / ml under dissolution conditions in which treatment is performed for 5 minutes using an ultrasonic disperser at room temperature. Then, a sample solution is obtained by processing with a membrane filter having a pore size of 0.2 μm, and 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent and detected using a refractive index detector (RI detector). The molecular weight distribution of the sample to be measured is a monodisperse polystyrene standard. Calculated using a calibration curve measured using quasi-particles. Ten polystyrenes are used for calibration curve measurement.

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

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 14, 17, 93, 94, 138, 156, 158, 180, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 60, etc. can be used, and a mixture thereof can also be used. The number average primary particle diameter varies depending on the type, but is preferably about 10 to 200 nm.

  As a method for adding the colorant, the resin fine particles are added at the stage of agglomeration by the addition of the flocculant to color the polymer. The colorant can be used by treating the surface with a coupling agent or the like.

(3) Wax (release agent)
Examples of the wax that can be used in the toner according to the present invention include conventionally known waxes. Specific examples include polyolefin waxes such as polyethylene wax and polypropylene wax, long-chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, and trimethylolpropane. Tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellit Ester waxes such as acid tristearyl and distearyl maleate, ethylenediamine dibehenyl amide, trimellitic acid tristearyl amide, etc. Such as amide waxes.

  The melting point of the wax is usually 40 to 160 ° C, preferably 50 to 120 ° C, more preferably 60 to 90 ° C. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the wax content in the toner is preferably 1% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

  The polymerization initiator, chain transfer agent, and surfactant that can be used in the toner production method will be described.

(4) Radical polymerization initiator usable in the present invention The resin constituting the core and shell constituting the toner according to the present invention is produced by polymerizing the aforementioned polymerizable monomer, but is used in the present invention. Possible radical polymerization initiators include the following. Specifically, as the oil-soluble polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane) -1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and other azo or diazo polymerization initiators, benzoyl peroxide, methyl ethyl ketone peroxide , Diisopropyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- ( 4,4-t-butylperoxycyclohexyl) propane Tris - like the like (t-butylperoxy) polymeric initiator having a side chain a peroxide-based polymerization initiator or a peroxide, such as triazines.

  Moreover, when forming resin particles by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.

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

  The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionate, terpinolene, carbon tetrabromide and α-methyl. Styrene dimer or the like is used.

(5) Dispersion stabilizer It is also possible to use a dispersion stabilizer in order to appropriately disperse the polymerizable monomer and the like in the reaction system. Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Furthermore, those generally used as surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

  The surfactant used in the present invention will be described.

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

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

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

[Image Forming Method, Image Forming Apparatus]
The toner of the present invention is suitably used in image forming methods and image forming apparatuses such as electrophotographic copying machines, printers and facsimiles.

  FIG. 1 is a cross-sectional configuration diagram illustrating an example of a color image forming apparatus.

  The color image forming apparatus 10 is called a tandem type full-color copying machine, and includes an automatic document feeder 13, a document image reading device 14, a plurality of exposure means 13Y, 13M, 13C, and 13K, and a plurality of sets of images. The forming units 10 </ b> Y, 10 </ b> M, 10 </ b> C, 10 </ b> K, the intermediate transfer body unit 17, the paper feeding unit 15, and the fixing unit 124 are included.

  An automatic document feeder 13 and a document image reading device 14 are arranged on the upper part of the main body 12 of the image forming apparatus, and an image of the document d conveyed by the automatic document feeder 13 is an optical system of the document image reading device 14. The image is reflected and imaged by the line image sensor CCD.

  The analog signal obtained by photoelectrically converting the original image read by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit (not shown), and then exposure means 13Y, 13M, 13C, and 13K are sent as digital image data for each color, and the exposure means 13Y, 13M, 13C, and 13K correspond to the corresponding drum-shaped photoconductors 11Y, 11M, 11C, and 11K as the corresponding first image carriers. A latent image of the image data is formed.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction, and can be rotated by winding rollers 171, 172, 173, and 174 around the left side of the photoreceptors 11Y, 11M, 11C, and 11K in the drawing. An intermediate transfer member (hereinafter, also referred to as an intermediate transfer belt) 170 of the present invention, which is a semiconductive and seamless belt-like second image carrier stretched on the belt, is disposed.

  The intermediate transfer belt 170 of the present invention is driven in the direction of the arrow through a roller 171 that is rotationally driven by a driving device (not shown).

  The image forming unit 10Y that forms a yellow image includes a charging unit 12Y, an exposure unit 13Y, a developing unit 14Y, a primary transfer roller 15Y as a primary transfer unit, and a cleaning unit 16Y disposed around the photoreceptor 11Y. Have.

  The image forming unit 10M that forms a magenta image includes a photoreceptor 11M, a charging unit 12M, an exposure unit 13M, a developing unit 14M, a primary transfer roller 15M as a primary transfer unit, and a cleaning unit 16M.

  The image forming unit 10C that forms a cyan image includes a photoreceptor 11C, a charging unit 12C, an exposure unit 13C, a developing unit 14C, a primary transfer roller 15C as a primary transfer unit, and a cleaning unit 16C.

  The image forming unit 10K that forms a black image includes a photoreceptor 11K, a charging unit 12K, an exposure unit 13K, a developing unit 14K, a primary transfer roller 15K as a primary transfer unit, and a cleaning unit 16K.

  The toner replenishing means 141Y, 141M, 141C, and 141K replenish new toner to the developing devices 14Y, 14M, 14C, and 14K, respectively.

  Here, the primary transfer rollers 15Y, 15M, 15C, and 15K are selectively operated according to the type of image by a control unit (not shown), and the intermediate transfer belt 170 is respectively applied to the corresponding photoreceptors 11Y, 11M, 11C, and 11K. To transfer the image on the photoreceptor.

  In this way, the images of the respective colors formed on the photoreceptors 11Y, 11M, 11C, and 11K by the image forming units 10Y, 10M, 10C, and 10K are rotated by the primary transfer rollers 15Y, 15M, 15C, and 15K. The image is sequentially transferred onto the intermediate transfer belt 170, and a combined color image is formed.

  That is, the intermediate transfer belt primarily transfers the toner image carried on the surface of the photosensitive member to the surface, and holds the transferred toner image.

  Further, the transfer material P as a recording medium accommodated in the paper feeding cassette 151 is fed by the paper feeding means 15 and then passed through a plurality of intermediate rollers 122A, 122B, 122C, 122D, and a registration roller 123, and the secondary material P. The toner image is conveyed to a secondary transfer roller 117 serving as a transfer unit, and the combined toner image on the intermediate transfer member is collectively transferred onto the transfer material P by the secondary transfer roller 117.

  That is, the toner image held on the intermediate transfer member is secondarily transferred to the surface of the transfer object.

  Here, the secondary transfer unit 6 presses the transfer material P against the intermediate transfer belt 170 only when the transfer material P passes through the secondary transfer unit 6 and performs the secondary transfer.

  The transfer material P onto which the color image has been transferred is fixed by the fixing device 124, sandwiched by the paper discharge roller 125, and placed on the paper discharge tray 126 outside the apparatus.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 117, the residual toner is removed by the cleaning unit 8 from the intermediate transfer belt 170 from which the transfer material P is separated by curvature.

  Here, the intermediate transfer member may be replaced with a rotating drum-like member as described above.

  Next, the configuration of the primary transfer rollers 15Y, 15M, 15C, and 15K as the primary transfer means in contact with the intermediate transfer belt 170 and the secondary transfer roller 117 will be described.

The primary transfer rollers 15Y, 15M, 15C, and 15K disperse a conductive material such as carbon in a rubber material such as polyurethane, EPDM, or silicone on a peripheral surface of a conductive core metal such as stainless steel having an outer diameter of 8 mm. Or containing an ionic conductive material, in a solid state or foamed sponge state with a volume resistance of about 1 × 10 ⁵ to 1 × 10 ⁹ Ω · cm, a thickness of 5 mm, and a rubber elastic modulus of 20 to It is formed by covering a semiconductive elastic rubber of about 70 ° (Asker elastic modulus C).

For example, the secondary transfer roller 117 disperses a conductive material such as carbon in a rubber material such as polyurethane, EPDM, or silicone on a peripheral surface of a conductive metal core such as stainless steel having an outer diameter of 8 mm, or an ionic conductive material. In a solid state or foamed sponge state with a volume resistance of about 1 × 10 ⁵ to 1 × 10 ⁹ Ω · cm by including a material, the thickness is 5 mm, and the rubber elastic modulus is about 20 to 70 ° (Asker elasticity It is formed by coating a semiconductive elastic rubber with a rate C).

[Transfer material]
The transfer material used in the present invention is a support for holding a toner image, and is usually called an image support, a transfer material, or transfer paper. Preferred examples include various kinds of transfer materials such as plain paper from thin paper to thick paper, coated printing paper such as art paper and coated paper, commercially available Japanese paper and postcard paper, plastic film for OHP, and cloth. However, it is not limited to these.

  Hereinafter, representative embodiments of the present invention will be shown to further explain the present invention. However, of course, the embodiment of the present invention is not limited to this. In the text, “part” means “part by mass”.

[Production of core particles]
(Preparation of core particle 1)
As described below, first-stage polymerization, second-stage polymerization, and then third-stage polymerization were performed to prepare “core particle 1” having a multilayer structure.

(1) First-stage polymerization In a 5 L (liter) reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, 4 parts of sodium polyoxyethylene-2-dodecyl ether sulfate is added to 3040 parts of ion-exchanged water. The dissolved surfactant solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant solution, an initiator solution in which 10 parts of a polymerization initiator (potassium persulfate: KPS) was dissolved in 400 parts of ion-exchanged water was added, the temperature was adjusted to 75 ° C., 532 parts of styrene, n- A monomer mixture composed of 200 parts of butyl acrylate, 68 parts of methacrylic acid and 16.4 parts of n-octyl mercaptan was added dropwise over 1 hour, and the system was polymerized by heating and stirring at 75 ° C. for 2 hours. (First stage polymerization) was performed to prepare resin particles. This is designated as “resin particle A1”.

  The “resin particle A1” prepared by the first stage polymerization had a mass average molecular weight (Mw) of 16,500.

(2) Second stage polymerization (formation of intermediate layer)
In a flask equipped with a stirrer, a monomer mixture consisting of 101.1 parts of styrene, 62.2 parts of n-butyl acrylate, 12.3 parts of methacrylic acid and 1.75 parts of n-octyl mercaptan was used as a release agent. Then, 93.8 parts of paraffin wax “HNP-57” (manufactured by Nippon Seiki Co., Ltd.) was added, and the mixture was heated to 90 ° C. and dissolved to prepare a monomer solution.

  On the other hand, a surfactant solution in which 3 parts of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 1560 parts of ion-exchanged water was heated to 98 ° C., and this surfactant solution was a dispersion of resin particles A1. After adding 32.8 parts of “resin particles A1” in terms of solid content, the wax monomer solution was mixed and dispersed for 8 hours by a mechanical disperser “CLEAMIX” (manufactured by M Technique Co., Ltd.) having a circulation path. A dispersion containing emulsified particles having a dispersed particle diameter of 340 nm was prepared.

  Next, an initiator solution prepared by dissolving 6 parts of potassium persulfate in 200 parts of ion-exchanged water was added to this dispersion, and this system was heated and stirred at 98 ° C. for 12 hours for polymerization (second stage polymerization). ) To obtain resin particles. This resin particle is referred to as “resin particle A2”. Mw of “resin particle A2” prepared by the second stage polymerization was 23,000.

(3) Third stage polymerization (formation of outer layer)
An initiator solution in which 5.45 parts of potassium persulfate is dissolved in 220 parts of ion-exchanged water is added to the “resin particles A2” obtained as described above, and styrene 293. A monomer mixed solution consisting of 8 parts, 154.1 parts of n-butyl acrylate, and 7.08 parts of n-octyl mercaptan was added dropwise over 1 hour. After completion of dropping, the mixture was heated and stirred for 2 hours to perform polymerization (third stage polymerization), and then cooled to 28 ° C. to obtain “resin particle 1 for core part”. Mw of “resin particle A3” prepared by the third stage polymerization was 26,800.

  The volume average particle diameter of the composite resin particles (resin particles) constituting the “core part resin particles 1” was 125 nm. The glass transition temperature (Tg) of the resin particles was 28.1 ° C.

  The glass transition temperature was taken as data in 2nd Heat using a DSC-7 differential scanning calorimeter (Perkin Elmer) and a TAC7 / DX thermal analyzer controller (Perkin Elmer).

[Production of shell particles]
(Preparation of resin particle 1 for shell layer)
In a flask equipped with a stirrer, AEROSIL 150 (as inorganic fine particles) was added to a monomer mixture consisting of 548 parts of styrene, 156 parts of 2-ethylhexyl acrylate, 96 parts of methacrylic acid, and 16.5 parts of n-octyl mercaptan. 80 parts) (manufactured by Nippon Aerosil Co., Ltd.) was added and heated to 60 ° C. to prepare a monomer mixed solution of inorganic fine particles.

  On the other hand, a surfactant solution in which 4 parts of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 3040 parts of ion-exchanged water was heated to 98 ° C., and a mechanical disperser having a circulation path was added to this surfactant solution. By “Cleamix” (manufactured by M Technique Co., Ltd.), the monomer mixed solution of the inorganic fine particles was mixed and dispersed for 8 hours to prepare a dispersion containing emulsified particles having a dispersed particle diameter of 410 nm.

  Next, an initiator solution in which 10 parts of potassium persulfate is dissolved in 400 parts of ion-exchanged water is added to this dispersion, and the temperature is adjusted to 75 ° C., and then the system is heated and stirred at 75 ° C. for 5 hours. Thus, polymerization was performed to prepare “resin particle 1 for shell layer”. The glass transition point (Tg) of the resin particles for shell layer was 54.0 ° C.

(Preparation of resin particle 2 for shell layer)
A surfactant solution in which 8 g of sodium dodecyl sulfate was dissolved in 3 L of ion-exchanged water was charged into a 5 L stainless steel kettle (SUS kettle) equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. The liquid temperature was raised to 80 ° C. while stirring at a speed.

  To this surfactant solution, an initiator solution in which 10 g of potassium persulfate was dissolved in 200 g of ion-exchanged water was added, the temperature was adjusted to 80 ° C., and the following monomer mixture was added dropwise over 100 minutes. Polymerization was carried out by heating and stirring the system at 80 ° C. for 2 hours to prepare resin particles 2 for shell layer.

Styrene 570 parts n-Butyl acrylate 165 parts Methacrylic acid 70 parts n-Octyl-3-mercaptopropionate 5.5 parts [Preparation of toner base particles]
(Preparation of dispersion 1 of colorant particles)
90 parts of sodium dodecyl sulfate was dissolved in 1600 parts of ion-exchanged water with stirring. While stirring this solution, 400 parts of carbon black “Regal 330” (Cabot Corporation) is gradually added, and then dispersed using a stirring device “Claremix” (Mtechnics Corporation). Agent particle dispersion 1 "was prepared.

  The particle diameter of the colorant particles in this “colorant particle dispersion liquid 1” was 110 nm as measured using an electrophoretic light scatterometer (ELS-800: manufactured by Otsuka Electronics Co., Ltd.).

(Preparation of toner base particles 1)
Salting out / fusion (association / fusion) process (core formation)
420 parts (converted to solid content) of “core part resin particles 1”, 900 parts of ion-exchanged water, and 200 parts of “colorant particle dispersion 1” were added to a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device. Was stirred in a reaction vessel equipped with. After adjusting the temperature in the container to 30 ° C., 5 mol / liter sodium hydroxide aqueous solution was added to this solution to adjust the pH to 9.0 ± 0.2.

Next, an aqueous solution in which 2 parts of magnesium chloride hexahydrate was dissolved in 1000 parts of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was raised and the system was heated to 65 ° C. over 60 minutes. In this state, the particle size of the associated particles was measured with “Coulter Multisizer 3” (manufactured by Coulter), and when the median diameter (D ₅₀ ) on the volume basis of the particles became 6.3 μm, sodium chloride 40. An aqueous solution in which 2 parts are dissolved in 1000 parts of ion-exchanged water is added to stop the growth of particle size, and further, the fusion is continued by heating and stirring at a liquid temperature of 70 ° C. for 1 hour as an aging treatment. Part 1 "was formed.

  The circularity of the “core part 1” was measured by “FPIA2100” (manufactured by Systex) and found to be 0.920.

(Formation of shell layer (shelling operation))
Next, at 65 ° C., 51.5 parts (converted to solid content) of “shell layer resin particles 1” was added, and an aqueous solution obtained by dissolving 2 parts of magnesium chloride hexahydrate in 1000 parts of ion-exchanged water was added for 10 minutes. After the addition, the temperature was raised to 70 ° C. (shelling temperature), and stirring was continued for 1 hour to fuse the particles of “resin particle 1 for shell layer” to the surface of “core part 1”. Thereafter, an aging treatment was performed at 75 ° C. to a predetermined circularity to form a shell layer. Thereafter, 40.2 parts of sodium chloride was added, the mixture was cooled to 30 ° C. under the condition of 8 ° C./min, and stirring was stopped.

(Washing / drying process)
The fused particles produced in the above process 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 exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner base particles 1 were prepared by drying until the amount reached 0.5% by mass.

(Preparation of toner base particles 2)
The toner base particles 2 were prepared in the same manner as the toner base particles 1 except that AEROXIDE TiO ₂ P25 was used instead of AEROSIL 150 in the preparation of the shell layer resin particles 1.

(Preparation of toner base particles 3)
The toner base particles 3 were prepared in the same manner as the toner base particles 1 except that AEROSIL 130 was used instead of AEROSIL 150 in the preparation of the resin particles 1 for the shell layer.

[Preparation of toner for comparison outside the present invention]
(Preparation of toner base particles 4)
<Resin H1 (Synthesis of high molecular weight resin (crosslinked polyester resin))
Raw materials such as an acid, an alcohol component, and a catalyst having the following composition were put into a 50 liter reaction kettle and reacted at 240 ° C. for 12 hours under a normal pressure nitrogen stream. Thereafter, the pressure was reduced successively, and the reaction was continued at 10 mmHg (1330 kPa). The reaction was followed by the softening point based on ASTM E28-517, and the reaction was terminated when the softening point reached 160 ° C.

Terephthalic acid: 9.06 parts by mass Isophthalic acid: 3.90 parts by mass Ethylene glycol: 2.54 parts by mass Neopentyl glycol: 4.26 parts by mass Tetrabutyl titanate: 0.1 parts by mass Epiclone 830: 0.3 parts by mass Dainippon Ink and Chemicals bisphenol F type epoxy resin epoxy equivalent 170 (g / eq)
Cardura E: 0.1 part by mass (Shell Japan alkyl glycidyl ester) epoxy equivalent 250 (g / eq)
The obtained polymer was a colorless solid, and had an acid value of 10.0 KOH mg / g, a glass transition temperature (Tg) of 64 ° C., and a softening temperature (T1 / 2) of 176 ° C. The weight average molecular weight was 210,000. However, the weight average molecular weight is a combination of TSK-GEL G5000HXL / G4000HXL / G3000HXL / G2000HXL manufactured by Tosoh as a separation column using a GPC measuring apparatus (HLC-8120GPC manufactured by Tosoh), column temperature: 40 ° C., solvent: tetrahydrofuran, solvent The molecular weight was determined by measuring at a concentration of 0.5% by mass, filter: 0.2 μm, flow rate: 1 ml / min, and conversion using standard polystyrene. The glass transition temperature (Tg) was measured using a differential scanning calorimeter (manufactured by Shimadzu Corp., DSC60-A), measuring temperature range: 20 to 150 ° C., temperature rising rate: 6 ° C./min, sample mass: 20 mg. Under the conditions described above, the curve at the time of temperature increase of the second run was obtained by analyzing by the onset method. The polymer was pulverized and sieved with a 2 mm sieve to obtain a powder.

  Silica fine particles (Aerosil 130, manufactured by Nippon Aerosil Co., Ltd.): 1200 parts by mass and hexamethyldisilazane (HMDS): 24 parts by mass are mixed and mixed in an organic solvent, the organic solvent is evaporated and sufficiently dried at 100 ° C., Hydrophobization treatment was applied to the surface of silica fine particles. The silica fine particles and resin H1 (powder): 2800 parts by mass were charged into a 20 L Henschel mixer (made by Mitsui Mining Co., Ltd.) in which ST / A0 blades were set, and the blade tip speed was stirred at 10 m / second for 2 minutes. A mixture was obtained. The mixture was melt-kneaded using an open roll continuous extrusion kneader (Mitsui Mining Co., Ltd. Needex MOS140-800) to obtain a silica-containing master chip. The mixing ratio was silica fine particles: resin H1 = 30: 70 in mass ratio.

  Next, 1050 parts by mass of methyl ethyl ketone was charged in a 3 L cylindrical container attached to a high-speed disperser (Primix Co., Ltd., TK Homodespar MARK II 2.5 blade), and the above silica-containing master chip: 700 parts by mass with stirring. Was gradually added to prepare a pre-mixed solution, and the mixed solution was mixed with an Eiger motor mill (M-1000, manufactured by Eiger Corp., USA) to refine the mixture. A silica-containing master solution was prepared by adjusting the solid content to 40%.

  Next, methyl ethyl ketone (diluted methyl ethyl ketone): 300 mass in a 2 L cylindrical vessel (desper blade diameter 40 mm) attached to a high-speed disperser (Primics Co., Ltd., TK Robotics / TK Homo Desper 2.5 type blade) Under a part charge and stirring, resin H1: 200 parts by mass was gradually added. Thereafter, dissolution and dispersion were carried out over 60 minutes under stirring conditions of a temperature of 30 to 50 ° C. and a blade tip speed of 7.5 m / sec. Thereafter, 250 parts by mass of a silica-containing master solution was added, and stirring was further continued for 30 minutes. The composition of the resin solution was silica fine particles: H1: MEK = 30: 270: 450. Thereafter, the temperature was lowered to 40 ° C. or lower and 1N ammonia water: 72 parts by mass was added, and then the stirring condition was adjusted from blade tip speed: 7.5 m / second to blade tip speed: 14.65 m / second. Under the stirring, 886 parts by mass of water was added dropwise at 20 parts by mass to obtain silica-containing resin dispersion SS-1. After emulsification, the obtained silica-containing resin dispersion SS-1 had a solid content of 17.31%, and the composition of the solid content was silica fine particles: H1 = 10: 90. The methyl ethyl ketone content was 31.95%.

<< Emulsion suspension preparation process >>
Subsequently, 1 mol / L aqueous ammonia: 50 parts by mass was added to the same container, and after stirring at a blade tip speed of 7.5 m / sec, the temperature was adjusted to 30 ° C. or lower.

  Thereafter, the blade tip speed was changed to 14.65 m / sec. In this state, 350 parts by mass of water (deionized water) was added dropwise at a rate of 20 parts by mass / min to prepare a dispersion. As deionized water was added, the viscosity of the system increased, but water was taken into the system at the same time as the addition, and stirring and mixing were uniform. A decrease in viscosity was observed when 210 parts by mass of deionized water was added (phase inversion point). Further, after a predetermined amount of the remaining deionized water was dropped (after 350 parts by mass of deionized water was dropped), 143.5 parts by mass of water was added as dilution water in a lump. The content of methyl ethyl ketone (organic solvent) in the dispersion at this stage was 29.0% by mass. In this dispersion, coarse particles having poor dispersibility were not observed.

<< Unification process >>
Next, after the dispersion was transferred to a Max Blend blade (blade diameter: 65 mm) and a 2 L cylindrical container attached to the condenser, the temperature was adjusted to 25 ° C. while maintaining the blade tip speed: 1.09 m / sec. did.

  Thereafter, the blade tip speed of the Max Blend blade was adjusted to 1.53 m / second, and 120 parts by mass of a 3.5% by mass sodium sulfate aqueous solution was added dropwise at 10 parts by mass / min. After completion of dropping, the blade tip speed was reduced from 1.53 m / second to 0.54 m / second over 15 minutes, and further stirred at 0.54 m / second for 20 minutes.

  Thereafter, the blade tip speed of the Max Blend blade was adjusted to 1.53 m / sec, and 10 parts by mass of a 5.0 mass% aqueous sodium sulfate solution was added dropwise. After the completion of dropping, the blade tip speed was adjusted to 0.54 m / sec, and stirring was continued until the particle size of the dispersoid (colored resin fine particles) became 4.5 μm.

  Here, the particle size was measured with Microtrac MT3000 (manufactured by Nikkiso Co., Ltd.), and the value of 50% volume particle size Dv (50) [μm] was defined as the particle size of the dispersoid (colored resin fine particles).

  When the particle size of the dispersoid reached 4.5 μm, the blade tip speed was maintained at 0.85 m / sec for 30 minutes. Here, this dispersion was observed. As a result, it was confirmed that coalescence of dispersoids (colored resin fine particles) was progressing. Furthermore, the particle diameter of the obtained coalesced particles was measured.

  As a result, when the 50% volume particle size is Dv (50) [μm] and the 50% number particle size is Dn (50) [μm], Dv (50) is 5.02 μm, Dv (50) / Dn (50) was 1.11. The particle size, particle size distribution, and the like of the obtained coalesced particles were measured with a Coulter Counter Multisizer II (Beckman Coulter, Inc.) using a 100 μm aperture tube. The other particles described below were similarly measured for particle size and particle size distribution. The average circularity R of the coalesced particles was 0.983. The average circularity was determined by measurement using a flow particle image analyzer (FPIP-1000, manufactured by Toa Medical Electronics Co., Ltd.). Moreover, the average circularity was calculated | required similarly about the other particle | grains demonstrated below.

<Coating process>
In the 2L cylindrical container in which the above coalescence process was performed, in a state where the blade tip speed of the Max Blend blade was accelerated from 0.85 m / sec to 1.53 m / sec, the silica-containing resin dispersion SS-1: 208 parts by mass (12 mass% with respect to 100 mass parts of core particles) was dropped at a rate of 5 mass parts / minute. After completion of dropping, the blade speed of the Max Blend blade was reduced from 1.53 m / sec to 1.00 m / sec, and stirring was further performed for 10 minutes while maintaining the blade tip speed. Thereafter, the blade tip speed was adjusted to 1.53 m / sec, and 5.0 parts by mass of a sodium sulfate aqueous solution: 20 parts by mass was added dropwise at 10 parts by mass / min. Thereafter, the blade tip speed was reduced from 1.53 m / second to 0.54 m / second over 15 minutes, and stirring was performed under the same conditions until the particle size grew to 5.8 μm while maintaining the blade tip speed. Continued. Thereafter, 400 parts by mass of water was added to stop coalescence of dispersoids. Thereby, a film was formed on the surface of the coalesced particles. The thickness of the formed film was measured by observing a cross section of toner particles after a drying step described later with a transmission electron microscope (TEM). As a result, the thickness of the formed film was 0.12 μm. Moreover, the particle size was measured about the dispersoid (coalescence particle) which has a film. As a result, after that, silicone-based antifoaming agent (manufactured by Toray Dow Corning Silicone, BY22-517): 0.068 parts by mass, and by reducing the pressure until the solid content is 23% by mass or more, Methyl ethyl ketone and a part of water were distilled off to obtain a slurry (colored resin fine particle slurry).

  Subsequent washing / drying steps were carried out in the same manner as toner base particles 1 to produce toner base particles 4.

(Preparation of toner base particles 5)
The toner base particles 5 were prepared in the same manner as the toner base particles 4 except that R-805 was used instead of AEROSIL 130 in the preparation of the toner base particles 4.

(Preparation of toner base particles 6)
In the preparation of the toner base particles 4, the toner base particles 6 were prepared in the same manner as in the preparation of the toner base particles 4 except that the thickness of the coating film in the coating step was halved and the AEROSIL 130 was changed to AEROSIL 150. Produced.

(Preparation of toner base particles 7)
The toner base particles 7 were prepared in the same manner as the toner base particles 1 except that the shell layer resin particles 2 were used instead of the shell layer resin particles 1.

[Production of toner]
With respect to 100 parts by mass of the toner base particles prepared above, 2.5% by mass of hydrophobic silica fine particles (number average primary particle size = 80 nm) and 0.3% of hydrophobic titania fine particles (number average primary particle size = 10 nm) are used. % Toner was added, and “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.) was used and mixed at a peripheral speed of 35 m / sec for 25 minutes to prepare “Toners 1 to 7”. The median diameter (D ₅₀ ) of the toner based on the volume was the same as that of the toner base particles.

  Table 1 below summarizes the types of inorganic particles added to the toner shell layer produced, the particle diameter, shape, and shell ratio of the toner.

[Evaluation of properties]
(Chile of fine dots)
A 10% halftone image was formed, and dust around the dots was observed with a loupe. The paper surface of the actual photograph sample (A4) was observed and ranked according to the following criteria.
◎: Dust that can hardly be detected ○: Dust slightly, but not noticeable unless you look closely ×: Dust can be easily detected (durability)
The degree of transfer of the external additive to the carrier after 20,000 actual shots was visually observed and ranked according to the following criteria.
A: No transition observed ○: Slight transition observed, but not noticeable unless stopped ×: Transition easily detected Table 2 shows the results.

  In Examples 1 to 3 in the present invention, all the characteristics are good, but it is understood that Comparative Examples 1 to 4 outside the present invention have problems in at least any of the characteristics.

DESCRIPTION OF SYMBOLS 1 Core shell type toner 2 Shell layer 3 Inorganic fine particle 4 Core particle 10Y, 10M, 10C, 10K Image formation part 14 Original image reading apparatus 13Y, 13M, 13C, 13K Exposure means 17 Intermediate transfer body unit 170 Intermediate transfer belts 171, 172, 173, 174 Intermediate transfer belt conveying roller

Claims (4)

A method for producing a core-shell type toner, which is produced through at least the following steps 1 to 4.
1: Step of producing core particles of core-shell toner 2: Step of dispersing inorganic fine particles in a monomer and dispersing this in an aqueous surfactant solution 3: Step of polymerizing the monomer to produce resin particles for a shell layer 4: A step of coating the surface of the core particles with resin particles for a shell layer to form a shell layer   2. The method for producing a core-shell toner according to claim 1, wherein the inorganic fine particles are silica particles having a number average particle diameter of 5 nm to 200 nm.   3. The method for producing a core-shell type toner according to claim 1, wherein the inorganic fine particles are fumed silica that is not subjected to a hydrophobic treatment.   The core-shell type according to any one of claims 1 to 3, wherein the binder resin contained in the resin particles for the shell layer has a weight average molecular weight (Mw) of 10,000 or more and 100,000 or less. Toner manufacturing method.

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