JP6068312B2 - Toner production method - Google Patents

Description

The present invention relates to a method of manufacturing a toner over, more particularly to a method of manufacturing a capsule toner over.

  Patent Document 1 discloses a capsule toner and a manufacturing method thereof. The capsule toner includes a core and a shell layer (capsule layer) formed on the surface of the core.

JP 2009-216914 A

  However, in the capsule toner manufacturing method described in Patent Document 1, it is difficult to control the characteristics of the shell layer. If the characteristics of the shell layer cannot be controlled, it is difficult to obtain a toner having the desired performance. For this reason, it is difficult to obtain a toner that is excellent in both fixability and heat-resistant storage stability only by the technique disclosed in Patent Document 1.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner excellent in both fixability and heat-resistant storage stability and a method for producing the same.

  The toner according to the present invention includes a plurality of toner particles. Each of the plurality of toner particles has a core and a shell layer formed on the surface of the core. The shell layer contains bubbles.

  The method for producing a toner according to the present invention includes a step of forming a core, a step of putting the material of the core and the shell layer into the liquid, a step of stirring and defoaming the liquid, and the defoamed liquid And forming the shell layer on the surface of the core.

  According to the present invention, it is possible to provide a toner excellent in both fixability and heat-resistant storage stability and a method for producing the same.

FIG. 3 is a diagram illustrating toner particles constituting the toner according to the exemplary embodiment of the present invention. 3 is a TEM photograph showing a cross section of toner particles constituting a toner according to an exemplary embodiment of the present invention. It is a figure for demonstrating the method of reading a glass transition point from an endothermic curve. It is a figure for demonstrating the method of reading a softening point from a S-shaped curve. 6 is a graph showing the relationship between the stirring speed (dispersing blade rotation speed) and the ratio of bubble diameters in the toner preparation method according to the example of the present invention. 6 is a graph showing the relationship between the defoaming time (stirring time) and the ratio of the bubble area in the toner preparation method according to an example of the present invention.

  Hereinafter, embodiments of the present invention will be described.

  The toner according to this embodiment is a capsule toner for developing an electrostatic image. The toner of this embodiment is a powder composed of a large number of particles (hereinafter referred to as toner particles). The toner according to the exemplary embodiment can be used in, for example, an electrophotographic apparatus.

  In an electrophotographic apparatus, an electrostatic image is developed using a developer containing toner. As a result, charged toner adheres to the electrostatic latent image formed on the photoreceptor. After the adhered toner is transferred to the transfer belt, the toner image on the transfer belt is further transferred to a recording medium (for example, paper). Thereafter, the toner is heated and fixed on the recording medium. As a result, an image is formed on the recording medium. For example, a full color image can be obtained by superimposing toner images of four colors of black, yellow, magenta and cyan.

  Hereinafter, the configuration of the toner (particularly toner particles) according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a view showing toner particles 10 constituting the toner according to the present embodiment. FIG. 2 is a TEM photograph showing a cross section of the toner particle 10.

  As shown in FIG. 1, the toner particle 10 includes a core 11, a shell layer 12 (capsule layer) formed on the surface of the core 11, and an external additive 13.

  The core 11 includes a binder resin 11a and an internal additive 11b (for example, a colorant, a release agent, a charge control agent, and magnetic powder). The core 11 is covered with a shell layer 12. An external additive 13 is attached to the surface of the shell layer 12.

  As shown in FIG. 2, the shell layer 12 contains bubbles 12a. By containing an appropriate amount of bubbles 12 a in the shell layer 12, it is possible to adjust the strength (or fragility) of the shell layer 12 and provide a toner excellent in both storability and fixability.

  In the toner according to the exemplary embodiment, in the cross section of the shell layer 12, the ratio of the average diameter of the bubbles 12a to the average thickness of the shell layer 12 is 0.3 or more and 0.5 or less. In the toner having such a configuration, the uniformity of the shell layer 12 is improved. For this reason, the toner according to the exemplary embodiment has excellent heat resistant storage stability.

  In the toner according to this embodiment, in the cross section of the shell layer 12, the ratio of the occupied area of the bubbles 12a to the area of the shell layer 12 is 0.1 or more and 0.3 or less. In the toner having such a configuration, the shell layer 12 has sufficient strength and moderate breakage. For this reason, the toner according to the exemplary embodiment has excellent fixability in a wide temperature range.

  The configuration of the toner particles is not limited to the above. For example, if not necessary, the internal additive 11b or the external additive 13 may be omitted. The toner particles may have a plurality of shell layers 12 on the surface of the core 11. When the toner particles have a plurality of shell layers 12 stacked, it is preferable that the outermost shell layer 12 among the plurality of shell layers 12 has a cationic property.

  It is preferable that the core 11 has an anionic property and the shell layer 12 has a cationic property. When the core 11 is anionic, the material of the cationic shell layer 12 can be attracted to the surface of the core 11 when the shell layer 12 is formed. Specifically, for example, the core 11 that is negatively charged in the aqueous medium and the material of the shell layer 12 that is positively charged in the aqueous medium are electrically attracted to each other, and the shell is formed on the surface of the core 11 by, for example, in-situ polymerization. Layer 12 is formed. This makes it easier to form a uniform shell layer 12 on the surface of the core 11 without highly dispersing the core 11 in the aqueous medium using a dispersant.

  In the core 11, the binder resin 11a occupies most of the core component (for example, 85% by mass or more). For this reason, the polarity of the binder resin 11a greatly affects the polarity of the entire core 11. For example, when the binder resin 11a has an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group, the core 11 has a strong tendency to become anionic. For example, the binder resin 11a has an amino group, When it has an amine or amide group, the core 11 has a strong tendency to become cationic.

  In the present embodiment, an indicator that the core 11 is anionic is that the zeta potential of the core 11 measured in an aqueous medium whose pH is adjusted to 4 indicates negative polarity. In order to strengthen the bond between the core 11 and the shell layer 12, it is preferable that the zeta potential of the core 11 at pH 4 is smaller than 0V and the zeta potential of the toner particles 10 at pH 4 is larger than 0V. In the present embodiment, pH 4 corresponds to the pH when the shell layer 12 is formed.

  Examples of the zeta potential measurement method include an electrophoresis method, an ultrasonic method, and an ESA (electroacoustic) method.

  In the electrophoresis method, an electric field is applied to the particle dispersion to cause electrophoresis of charged particles in the dispersion, and the zeta potential is calculated based on the electrophoresis speed. Examples of the electrophoresis method include a laser Doppler method (a method in which an electrophoresis speed is obtained from the amount of Doppler shift of the obtained scattered light by irradiating the electrophoretic particles with laser light). The laser Doppler method has the advantage that the particle concentration in the dispersion does not need to be high, the number of parameters necessary for calculating the zeta potential is small, and the electrophoresis speed can be detected with high sensitivity.

  The ultrasonic method is a method of irradiating a particle dispersion with ultrasonic waves to vibrate charged particles in the dispersion and calculating a zeta potential based on a potential difference caused by the vibration.

  In the ESA method, a high frequency voltage is applied to the particle dispersion to vibrate charged particles in the dispersion to generate ultrasonic waves. Then, the zeta potential is calculated from the magnitude (intensity) of the ultrasonic waves.

  The ultrasonic method and the ESA method have an advantage that the zeta potential can be measured with high sensitivity even in a particle dispersion having a high particle concentration (for example, exceeding 20% by mass).

  In this embodiment, neither the core 11 nor the shell layer 12 has a dispersant (surfactant). Generally, a dispersant has a high drainage load. If no dispersant is used, the amount of water used in the cleaning process can be reduced. In addition, if no dispersant is used, the total organic carbon (TOC) concentration in the wastewater can be reduced to a low level of 15 mg / L or less without diluting the wastewater discharged when the toner particles 10 are produced. Become.

  It should be noted that by measuring the biochemical oxygen demand (BOD), chemical oxygen demand (COD), or total organic carbon (TOC) concentration, organic components (for example, unreacted monomers, prepolymers) in wastewater , Or dispersant). Above all, based on the TOC concentration, it is possible to stably measure all organic substances. Moreover, the quantity of the organic component which did not contribute to the encapsulation in waste water (The whole filtrate and washing | cleaning liquid after reaction) can be specified by measuring a TOC density | concentration.

  Hereinafter, the core 11 (binder resin 11a and internal additive 11b), shell layer 12, and external additive 13 will be described in order.

[core]
The core 11 includes a binder resin 11a and an internal additive 11b (coloring agent, release agent, charge control agent, and magnetic powder). However, unnecessary components (for example, a colorant, a release agent, a charge control agent, or magnetic powder) may be omitted depending on the use of the toner.

[Binder resin (core)]
Hereinafter, the binder resin 11a will be described.

  In order to obtain a strong anionic property of the binder resin 11a, the hydroxyl value (OHV value) and the acid value (AV value) of the binder resin 11a are each preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more. It is more preferable.

  The glass transition point (Tg) of the binder resin 11a is preferably equal to or lower than the curing start temperature of the thermosetting resin included in the shell layer 12. If such a binder resin 11a is used, sufficient fixability can be easily obtained even during high-speed fixing. Further, the curing start temperature of thermosetting resins (particularly melamine resins) is often about 55 ° C. The Tg of the binder resin 11a is preferably 20 ° C. or higher, more preferably 30 ° C. or higher and 55 ° C. or lower, and further preferably 30 ° C. or higher and 50 ° C. or lower. When the Tg of the binder resin 11a is 20 ° C. or higher, the core 11 is less likely to aggregate when the shell layer 12 is formed.

  The softening point (Tm) of the binder resin 11a is preferably 100 ° C. or less, and more preferably 95 ° C. or less. When the Tm of the binder resin 11a is 100 ° C. or lower (more preferably 95 ° C. or lower), sufficient fixability can be obtained even during high-speed fixing. Further, if the Tm of the binder resin 11a is 100 ° C. or lower (more preferably 95 ° C. or lower), the shell layer 12 is cured during the curing reaction when the shell layer 12 is formed on the surface of the core 11 in an aqueous medium. Since the core 11 is partially softened easily, the core 11 is easily rounded by surface tension. In addition, Tm of the binder resin 11a can be adjusted by combining a plurality of binder resins having different Tm.

  Hereinafter, a method of reading Tg of the binder resin 11a from the endothermic curve will be described with reference to FIG. FIG. 3 is a graph showing an example of an endothermic curve.

  In measuring Tg, an endothermic curve is measured using a differential scanning calorimeter (for example, “DSC-6220” manufactured by Seiko Instruments Inc.). For example, an endothermic curve as shown in FIG. 3 is obtained. The Tg of the binder resin 11a can be obtained from the change point of the specific heat in the endothermic curve of the binder resin 11a.

  Next, a method for reading Tm of the binder resin 11a from the S-shaped curve will be described with reference to FIG. FIG. 4 is a graph showing an example of an S-shaped curve.

  Tm of the binder resin 11a can be measured using an elevated flow tester (for example, “CFT-500D” manufactured by Shimadzu Corporation). Specifically, the measurement sample is set on an elevated flow tester, and the sample is melted and flowed out under predetermined conditions. Thereby, an S-shaped curve (S-shaped curve related to temperature (° C.) / Stroke (mm)) is obtained. The Tm of the binder resin 11a can be read from the obtained S-shaped curve. In FIG. 4, S1 indicates the maximum stroke value, and S2 indicates the baseline stroke value on the low temperature side. The temperature at which the stroke value in the S-shaped curve is (S1 + S2) / 2 is defined as Tm of the measurement sample.

The description will be continued with reference to FIG.
The binder resin 11a is preferably composed of a resin having, for example, an ester group, a hydroxyl group, an ether group, an acid group, a methyl group, a carboxyl group, or an amino group as a functional group. The binder resin 11a is preferably a resin having a functional group such as a hydroxyl group, a carboxyl group, or an amino group in the molecule, and more preferably a resin having a hydroxyl group and / or a carboxyl group in the molecule. The core 11 (binder resin 11a) having such a functional group easily reacts with the material of the shell layer 12 (for example, methylol melamine) and is easily chemically bonded. When such a chemical bond occurs, the bond between the core 11 and the shell layer 12 becomes strong.

  As the binder resin 11a, a thermoplastic resin is preferable.

  Preferred examples of the thermoplastic resin include styrene resin, acrylic resin, styrene acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, and polyvinyl alcohol. Examples thereof include a resin, a vinyl ether resin, an N-vinyl resin, and a styrene-butadiene resin. Among them, the styrene acrylic resin and the polyester resin are excellent in the dispersibility of the colorant in the toner, the charging property of the toner, and the fixing property to the recording medium, respectively.

(Styrene acrylic resin)
Hereinafter, the styrene acrylic resin as the binder resin 11a will be described.

  The styrene acrylic resin is, for example, a copolymer of a styrene monomer and an acrylic monomer.

  Preferable examples of the styrenic monomer include styrene, α-methylstyrene, p-hydroxystyrene, m-hydroxystyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chloro. Styrene or p-ethylstyrene is mentioned.

  Preferable examples of the acrylic monomer include (meth) acrylic acid, particularly (meth) acrylic acid alkyl ester or (meth) acrylic acid hydroxyalkyl ester. Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, iso-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, methyl (meth) methacrylate, ethyl (meth) methacrylate, n-butyl (meth) methacrylate, or (meth) Iso-butyl methacrylate is preferred. Examples of (meth) acrylic acid hydroxyalkyl esters include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, or 4- (meth) acrylic acid 4- Hydroxypropyl is preferred.

  When preparing a styrene acrylic resin, a monomer having a hydroxyl group (for example, p-hydroxystyrene, m-hydroxystyrene, or hydroxyalkyl (meth) acrylate) is used to add a hydroxyl group to the styrene acrylic resin. Can be introduced. For example, the hydroxyl value of the obtained styrene acrylic resin can be adjusted by appropriately adjusting the amount of the monomer having a hydroxyl group.

  When preparing the styrene acrylic resin, a carboxyl group can be introduced into the styrene acrylic resin by using (meth) acrylic acid as a monomer. For example, the acid value of the resulting styrene acrylic resin can be adjusted by appropriately adjusting the amount of (meth) acrylic acid used.

  In order to improve the strength or fixability of the core 11, the number average molecular weight (Mn) of the styrene acrylic resin as the binder resin 11 a is preferably 2000 or more and 3000 or less. The molecular weight distribution of the styrene acrylic resin (ratio Mw / Mn of the mass average molecular weight (Mw) to the number average molecular weight (Mn)) is preferably 10 or more and 20 or less. Gel permeation chromatography can be used for the measurement of Mn and Mw of the binder resin 11a.

(Polyester resin)
Hereinafter, the polyester resin as the binder resin 11a will be described.

  The polyester resin can be obtained, for example, by polycondensation or copolycondensation of a divalent or trivalent or higher alcohol component and a divalent or trivalent or higher carboxylic acid component.

  Preferable examples of the divalent or trivalent or higher alcohol component of the polyester resin include diols, bisphenols, and trivalent or higher alcohols.

  Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5 -Pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol or polytetramethylene glycol are preferred.

  As the bisphenols, for example, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, or polyoxypropylenated bisphenol A is preferable.

  Examples of the trivalent or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, or 1,3,5-trihydroxy Methylbenzene is preferred.

  As the divalent or trivalent or higher carboxylic acid component of the polyester resin, for example, an ester-forming derivative (eg, acid halide, acid anhydride, or lower alkyl ester) may be used. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  Examples of the divalent carboxylic acid include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid. Or alkyl or alkenyl succinic acid. Furthermore, examples of the alkenyl succinic acid include n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, and n-dodecenyl succinic acid. , Isododecyl succinic acid, or isododecenyl succinic acid.

  Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4. -Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid Acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid are preferred.

  When the polyester resin is produced, the acid value and hydroxyl group of the polyester resin are appropriately changed by appropriately changing the amount of the divalent or trivalent or higher alcohol component and the amount of the divalent or trivalent or higher carboxylic acid component. The price can be adjusted. Moreover, when the molecular weight of the polyester resin is increased, the acid value and hydroxyl value of the polyester resin tend to decrease.

  In order to improve the strength or fixability of the core 11, the number average molecular weight (Mn) of the polyester resin as the binder resin 11a is preferably 1200 or more and 2000 or less. The molecular weight distribution (the ratio Mw / Mn of the mass average molecular weight (Mw) to the number average molecular weight (Mn)) of the polyester resin is preferably 9 or more and 20 or less. Gel permeation chromatography can be used for the measurement of Mn and Mw of the binder resin 11a.

[Colorant (core)]
Hereinafter, the colorant contained in the core 11 (internal additive 11b) will be described.

  As the colorant, for example, a known pigment or dye can be used according to the color of the toner particles 10. The amount of the colorant to be used is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin 11a.

(Black colorant)
The core 11 of the toner particles 10 according to the present embodiment may contain a black colorant. The black colorant is composed of, for example, carbon black. In addition, a colorant that is toned to black using a colorant such as a yellow colorant, a magenta colorant, and a cyan colorant can also be used.

(Coloring agent)
The core 11 of the toner particle 10 according to the present embodiment may contain a color colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.

  The yellow colorant is preferably composed of, for example, a condensed azo compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex, a methine compound, or an allylamide compound. Examples of yellow colorants include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155 168, 174, 175, 176, 180, 181, 191 or 194), Neftol Yellow S, Hansa Yellow G, or C.I. I. Butt yellow is preferred.

  The magenta colorant is preferably composed of, for example, a condensed azo compound, diketopyrrolopyrrole compound, anthraquinone compound, quinacridone compound, basic dye lake compound, naphthol compound, benzimidazolone compound, thioindigo compound, or perylene compound. Examples of magenta colorants include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177 184, 185, 202, 206, 220, 221 or 254).

  The cyan colorant is preferably composed of, for example, a copper phthalocyanine compound, a copper phthalocyanine derivative, an anthraquinone compound, or a basic dye lake compound. Examples of cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66), phthalocyanine blue, C.I. I. Bat Blue, or C.I. I. Acid blue is preferred.

[Release agent (core)]
Hereinafter, the mold release agent contained in the core 11 (internal additive 11b) will be described.

  The release agent is used for the purpose of improving the fixing property or offset resistance of the toner. In order to improve the fixing property or the offset resistance, the amount of the release agent used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin 11a. It is more preferable that the amount is not more than part by mass.

  In one example, the release agent may be composed of an aliphatic hydrocarbon wax such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or Fischer-Tropsch wax. preferable. In another example, the release agent is preferably composed of an oxide of an aliphatic hydrocarbon wax such as an oxidized polyethylene wax or a block copolymer of oxidized polyethylene wax. In another example, it is preferred that the release agent is composed of a vegetable wax such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax. In another example, the release agent is preferably composed of animal wax such as beeswax, lanolin, or spermaceti. In another example, the release agent is preferably composed of a mineral wax such as ozokerite, ceresin, or vetrolactam. In another example, it is preferable that the mold release agent is composed of waxes based on fatty acid esters such as montanic acid ester wax or caster wax. In another example, it is preferable that the release agent is composed of a wax obtained by deoxidizing a part or all of a fatty acid ester such as deoxidized carnauba wax.

[Charge control agent (core)]
Hereinafter, the charge control agent contained in the core 11 (internal additive 11b) will be described.

  In the present embodiment, since the core 11 has an anionic property (negative chargeability), a negatively chargeable charge control agent is used in the core 11. The charge control agent is used for the purpose of improving the charge stability or charge rising property and obtaining a toner having excellent durability or stability. The charge rising characteristic is an index as to whether or not the toner can be charged to a predetermined charge level in a short time.

[Magnetic powder (core)]
Hereinafter, the magnetic powder contained in the core 11 (internal additive 11b) will be described.

  When toner is used as a one-component developer, the amount of magnetic powder used is preferably 35 parts by weight or more and 60 parts by weight or less, and 40 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the total amount of toner. It is more preferable.

  Magnetic powder is made ferromagnetized, for example, iron (ferrite or magnetite), ferromagnetic metal (cobalt or nickel), alloy containing iron and / or ferromagnetic metal, compound containing iron and / or ferromagnetic metal, heat treatment It is preferably composed of a processed ferromagnetic alloy or chromium dioxide.

  The particle size of the magnetic powder is preferably 0.1 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When the particle diameter of the magnetic powder is in such a range, the magnetic powder can be easily dispersed uniformly in the binder resin 11a.

[Shell layer]
As a material of the shell layer 12, a material that is dispersed in water is preferable.

  The shell layer 12 is preferably composed of a thermosetting resin, and more preferably composed of a resin containing a nitrogen atom or a derivative thereof in order to improve strength, hardness, or cationicity. When the shell layer 12 contains nitrogen atoms, the shell layer 12 is easily positively charged. In order to increase the cationic property, the content of nitrogen atoms in the shell layer 12 is preferably 10% by mass or more.

  As the thermosetting resin constituting the shell layer 12, for example, melamine resin, urea (urea) resin, sulfoamide resin, glyoxal resin, guanamine resin, aniline resin, or derivatives of these resins are preferable. As the melamine resin derivative, for example, methylol melamine is preferable. As the guanamine resin derivative, for example, benzoguanamine, acetoguanamine, or spiroguanamine is preferable.

  As the thermosetting resin constituting the shell layer 12, for example, a polyimide resin having a nitrogen element in the molecular skeleton, a maleide polymer, bismuthimide, aminobismuthimide, or bismuthimidetriazine is preferable.

  Examples of the thermosetting resin constituting the shell layer 12 include a resin (hereinafter referred to as an aminoaldehyde resin) produced by polycondensation of a compound containing an amino group and an aldehyde (for example, formaldehyde), or a derivative of an aminoaldehyde resin. Particularly preferred. The melamine resin is, for example, a polycondensate of melamine and formaldehyde. The urea resin is a polycondensate of urea and formaldehyde, for example. Glyoxal resin is, for example, a polycondensate of a reaction product of glyoxal and urea with formaldehyde.

  Of the resins contained in the shell layer 12, 80% by mass or more of the resin is preferably a thermosetting resin, 90% by mass or more of the resin is more preferably a thermosetting resin, and 100% by mass of the resin is hot. More preferably, it is a cured resin.

  The thickness of the shell layer 12 is preferably 1 nm or more and 20 nm or less, and more preferably 1 nm or more and 10 nm or less.

  When the thickness of the shell layer 12 is 20 nm or less, the shell layer 12 is easily broken by heat and pressure when fixing the toner to the recording medium. As a result, the binder resin 11a and the release agent contained in the core 11 are rapidly softened or melted, and the toner can be fixed on the recording medium in a low temperature range. Furthermore, when the thickness of the shell layer 12 is 20 nm or less, the chargeability of the shell layer 12 does not become too strong, so that an image is properly formed.

  On the other hand, when the thickness of the shell layer 12 is 1 nm or more, the shell layer 12 has sufficient strength, and the destruction of the shell layer 12 due to impact during transportation can be suppressed.

  The thickness of the shell layer 12 can be measured by analyzing a cross-sectional TEM image of the toner particles 10 using commercially available image analysis software (for example, “WinROOF” manufactured by Mitani Corporation).

  In the present embodiment, the shell layer 12 has a cationic property (positive charging property). For this reason, the shell layer 12 may contain a positively chargeable charge control agent.

[External additive]
Hereinafter, the external additive 13 will be described. Hereinafter, the particles before being treated with the external additive 13 are referred to as “toner mother particles”.

  The external additive 13 is used to improve the fluidity or handleability of the toner particles 10 and adheres to the surface of the shell layer 12. In order to improve fluidity or handleability, the amount of the external additive 13 used is preferably 0.5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the toner base particles. More preferably, it is 5 parts by mass or less.

  The external additive 13 is preferably composed of, for example, silica or a metal oxide (for example, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, or barium titanate).

  In order to improve fluidity or handleability, the particle diameter of the external additive 13 is preferably 0.01 μm or more and 1.0 μm or less.

Next, a toner manufacturing method according to this embodiment will be described.
In the toner manufacturing method according to the present embodiment, the core 11 is formed. Subsequently, the material of the core 11 and the shell layer 12 is put into the liquid. Subsequently, the liquid is stirred and degassed. Subsequently, the defoamed liquid is heated to form a shell layer 12 on the surface of the core 11. According to such a method, the shell layer 12 containing the bubbles 12a can be easily and appropriately formed on the surface of the core 11.

  In the toner manufacturing method according to the present embodiment, the rotational speed of stirring in the defoaming step is controlled in the range of 1100 rpm to 1300 rpm, so that the average thickness of the shell layer 12 in the cross section of the shell layer 12 after formation is controlled. The ratio of the average diameter of the bubbles 12a in the shell layer 12 can be adjusted to 0.3 or more and 0.5 or less. According to such a method, the ratio of the bubbles 12a in the shell layer 12 (average diameter of the bubbles 12a / average thickness of the shell layer 12) is easily and appropriately adjusted to a desired range (0.3 or more and 0.5 or less). It becomes possible.

  In the toner manufacturing method according to the present embodiment, the agitation time in the defoaming step is controlled in the range of 30 minutes to 100 minutes, whereby the shell layer relative to the area of the shell layer 12 in the cross section of the shell layer 12 after formation is controlled. The ratio of the occupied area of the bubbles 12a in 12 can be adjusted to 0.1 or more and 0.3 or less. According to such a method, the ratio of the bubbles 12a (occupied area of the bubbles 12a / the area of the shell layer 12) in the shell layer 12 can be easily and appropriately adjusted to a desired range (0.1 or more and 0.3 or less). It becomes possible.

  In the toner manufacturing method according to the exemplary embodiment, the stirring is performed in an environment where the gauge pressure is −0.100 MPa or more and −0.085 MPa or less. Defoaming can be promoted by performing defoaming in a reduced pressure environment close to vacuum.

  Examples of the present invention will be described. In this example, toners A to Q (see Table 1 described later) were evaluated. Hereinafter, a preparation method, an evaluation method, and an evaluation result of toners A to Q will be described in order.

[Method for Preparing Toner A]
A method for preparing toner A will be described.

(Production of core)
Hereinafter, a procedure for producing the core 11 in the method for preparing the toner A will be described.

  In the preparation method of the toner A, a low viscosity polyester resin 750 g, a medium viscosity polyester resin 100 g, a high viscosity polyester resin 150 g, and a release agent 55 g using a mixer (“Henschel mixer” manufactured by Nippon Coke Industries, Ltd.). And 40 g of the colorant were mixed at a rotational speed of 2400 rpm. By increasing the ratio of the low-viscosity polyester resin in the binder resin 11a (polyester resin), the melt viscosity of the binder resin 11a can be lowered. In the preparation method of the toner A, the melt viscosity of the binder resin 11a at 93 ° C. was adjusted to 8000 Pa · s. A flow tester (“CFT-500D” manufactured by Shimadzu Corporation) was used to measure the viscosity.

  In the low viscosity polyester resin, Tg is 38 ° C. and Tm is 65 ° C. In the medium viscosity polyester resin, Tg is 53 ° C. and Tm is 84 ° C. In the high viscosity polyester resin, Tg is 71 ° C. and Tm is 120 ° C.

  As a colorant, “KET Blue 111” (phthalocyanine blue) manufactured by DIC Corporation was used. As the release agent, “Carnauba Wax No. 1” manufactured by Hiroyuki Kato Co., Ltd. was used.

  Subsequently, the obtained mixture was mixed using a biaxial extruder (“PCM-30” manufactured by Ikegai Co., Ltd.) with a material input amount of 5 kg / hour, a shaft rotation speed of 160 rpm, and a set temperature range of 100 ° C. to 130 ° C. It was melt-kneaded under conditions. Thereafter, the obtained melt-kneaded product was cooled.

  Subsequently, the melt-kneaded material was roughly pulverized using a mechanical pulverizer (“Rotoplex 16/8 type” manufactured by Toa Machinery Co., Ltd.). Further, the coarsely pulverized product was finely pulverized using a jet mill (“Ultrasonic Jet Mill I Type” manufactured by Nippon Pneumatic Industry Co., Ltd.). Subsequently, the finely pulverized product was classified using a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.). As a result, a core 11 having a median diameter (volume distribution standard) of 6.0 μm was obtained. The core 11 was anionic.

(Formation of shell layer)
Hereinafter, a procedure for forming the shell layer 12 in the method for preparing the toner A will be described.

  A 1 L three-necked flask equipped with a thermometer and a stirring blade was prepared, and 500 mL of ion-exchanged water and sodium polyacrylate (“Jurimer (registered trademark) AC-103” manufactured by Toagosei Co., Ltd.) were prepared in the flask. 50 g was added. Thereby, the sodium polyacrylate aqueous solution was obtained in the flask.

  Subsequently, 100 g of the core 11 produced by the above-described procedure was added to the sodium polyacrylate aqueous solution. Thereafter, the contents of the flask were sufficiently stirred at room temperature. Thereby, the dispersion liquid of the core 11 was obtained in the flask.

  Subsequently, the dispersion liquid of the core 11 was filtered using a filter paper having an opening of 3 μm. Thereby, the core 11 was separated by filtration. Subsequently, the core 11 was redispersed in ion exchange water. Thereafter, the core 11 was washed by repeating filtration and redispersion five times. Subsequently, a suspension in which 100 g of the core 11 was dispersed in 500 mL of ion exchange water was prepared in the flask.

  Subsequently, 1 g of methylolated urea (“Milben Resin SU-100” manufactured by Showa Denko KK) was added to the flask, and the contents of the flask were stirred to dissolve the methylolated urea in the suspension. Subsequently, dilute hydrochloric acid was added to the flask to adjust the pH of the suspension in the flask to 4. Subsequently, in an environment reduced to a gauge pressure of -0.096 MPa, using a stirring deaerator ("SNW-VS" manufactured by Sampratec Co., Ltd.) equipped with a Despa type dispersion blade having a diameter of 50 mm, the dispersion blade rotation speed is 1200 rpm. The suspension was stirred for 45 minutes. Thereby, the suspension was degassed. In addition, it is thought that the air bubbles which mainly entered during the kneading remained in the suspension before defoaming.

  Subsequently, the suspension was transferred to a 1 L separable flask. Subsequently, the contents of the flask were heated with stirring (the temperature in the flask was raised to 70 ° C.), and the state at 70 ° C. was maintained for 2 hours. Thereby, the core 11 and the material of the shell layer 12 polymerized in the flask, and the cationic shell layer 12 composed of a thermosetting resin (urea resin) was formed on the surface of the core 11. As a result, a dispersion containing toner mother particles was obtained. Thereafter, sodium hydroxide was added to adjust (neutralize) the pH of the dispersion to 7. The dispersion was cooled to room temperature (25 ° C.).

(Washing and drying)
After the toner base particles (core 11 and shell layer 12) were formed, the dispersion was filtered (solid-liquid separation) to obtain toner base particles. Thereafter, the toner base particles were redispersed in ion exchange water. Further, the toner base particles were washed by repeating dispersion and filtration. Thereafter, the toner base particles were dried. Since washing (dispersion and filtration) was repeated, almost no dispersant (sodium polyacrylate) remained inside and on the surface of the toner base particles.

(External)
Dry silica fine particles (“REA90” manufactured by Nippon Aerosil Co., Ltd.) as an external additive 13 were mixed at a ratio of 1.5 mass% with respect to the toner base particles obtained by the drying step. As a result, a toner A having a large number of toner particles 10 was obtained.

[Method for Preparing Toner B]
The preparation method of the toner B is substantially the same as the preparation method of the toner A except that the stirring speed (dispersion blade rotation speed) is changed from 1200 rpm to 1300 rpm regarding the defoaming conditions of the liquid containing the material of the shell layer 12.

[Method for Preparing Toner C]
The preparation method of the toner C is substantially the same as the preparation method of the toner A except that the stirring speed (dispersion blade rotation speed) is changed from 1200 rpm to 1100 rpm regarding the defoaming conditions of the liquid containing the material of the shell layer 12. FIG. 2 is a TEM photograph showing a cross section of the toner particles 10 contained in the toner C.

[Method for Preparing Toner D]
The preparation method of the toner D relates to the defoaming conditions of the liquid containing the material of the shell layer 12, the stirring speed (dispersion blade rotation speed) is changed from 1200 rpm to 1250 rpm, and the defoaming time (stirring time) is 45 minutes to 30 minutes. The method is almost the same as the preparation method of the toner A except that

[Method for Preparing Toner E]
The toner E is prepared by changing the defoaming environment from gauge pressure -0.096 MPa to gauge pressure -0.098 MPa with respect to the defoaming conditions of the liquid containing the material of the shell layer 12, and stirring speed (dispersion blade rotation speed). Is substantially the same as the preparation method of the toner A except that the defoaming time (stirring time) is changed from 45 minutes to 60 minutes.

[Method for Preparing Toner F]
The toner F is prepared by changing the defoaming environment from a gauge pressure of -0.096 MPa to a gauge pressure of -0.089 MPa and defoaming time (stirring time) with respect to the defoaming conditions of the liquid containing the material of the shell layer 12. Except for changing from 45 minutes to 100 minutes, it is almost the same as the preparation method of toner A.

[Method for Preparing Toner G]
Toner G was prepared by using toner A except that methylol melamine (“Nikaresin S-176” manufactured by Nippon Carbide Industries, Ltd.) was used instead of methylolated urea (“Milben Resin SU-100” manufactured by Showa Denko KK). This is almost the same as the preparation method. The addition amount of methylol melamine (“Nika Resin S-176” manufactured by Nippon Carbide Industries Co., Ltd.) was 1 g.

[Method for Preparing Toner H]
Toner H was prepared by using toner A except that methylol melamine (“Nikaresin S-260” manufactured by Nippon Carbide Industries, Ltd.) was used instead of methylolated urea (“Milben Resin SU-100” manufactured by Showa Denko KK). This is almost the same as the preparation method. The addition amount of methylol melamine (“Nika Resin S-260” manufactured by Nippon Carbide Industries Co., Ltd.) was 1 g.

[Method for Preparing Toner I]
The preparation method of the toner I is substantially the same as the preparation method of the toner A except that the defoaming time (stirring time) is changed from 45 minutes to 15 minutes with respect to the defoaming conditions of the liquid containing the material of the shell layer 12. .

[Method for Preparing Toner J]
The preparation method of the toner J is generally the same as the preparation method of the toner A except that the defoaming time (stirring time) is changed from 45 minutes to 120 minutes with respect to the defoaming conditions of the liquid containing the material of the shell layer 12. .

[Method for Preparing Toner K]
The preparation method of the toner K is substantially the same as the preparation method of the toner A, except that the stirring speed (dispersion blade rotation speed) is changed from 1200 rpm to 1000 rpm regarding the defoaming conditions of the liquid containing the material of the shell layer 12.

[Method for Preparing Toner L]
The preparation method of the toner L is substantially the same as the preparation method of the toner A except that the stirring speed (dispersion blade rotation speed) is changed from 1200 rpm to 1500 rpm regarding the defoaming conditions of the liquid containing the material of the shell layer 12.

[Method for Preparing Toner M]
The toner M is prepared by changing the defoaming environment from a gauge pressure of -0.096 MPa to a gauge pressure of -0.099 MPa and defoaming time (stirring time) with respect to the defoaming conditions of the liquid containing the material of the shell layer 12. Except for changing from 45 minutes to 60 minutes, it is almost the same as the preparation method of toner A.

[Method for Preparing Toner N]
The toner N is prepared by changing the defoaming environment from a gauge pressure of -0.096 MPa to a gauge pressure of -0.087 MPa and defoaming time (stirring time) with respect to the defoaming conditions of the liquid containing the material of the shell layer 12. Except for changing from 45 minutes to 30 minutes, it is almost the same as the preparation method of toner A.

[Method for Preparing Toner O]
Toner O was prepared by using toner I except that methylol melamine (“Nikaresin S-176” manufactured by Nippon Carbide Industries, Ltd.) was used instead of methylolated urea (“Milben Resin SU-100” manufactured by Showa Denko KK). This is almost the same as the preparation method. The addition amount of methylol melamine (“Nika Resin S-176” manufactured by Nippon Carbide Industries Co., Ltd.) was 1 g.

[Method for Preparing Toner P]
The toner P was prepared by using toner I except that methylol melamine (“Nikaresin S-260” manufactured by Nippon Carbide Industries, Ltd.) was used instead of methylolated urea (“Milben Resin SU-100” manufactured by Showa Denko KK). This is almost the same as the preparation method. The addition amount of methylol melamine (“Nika Resin S-260” manufactured by Nippon Carbide Industries Co., Ltd.) was 1 g.

[Method for Preparing Toner Q]
The toner Q is prepared by changing the defoaming environment from a gauge pressure of -0.096 MPa to a gauge pressure of -0.099 MPa with respect to the defoaming conditions of the liquid containing the material of the shell layer 12, and stirring speed (dispersion blade rotation speed). Is substantially the same as the preparation method of the toner A except that the defoaming time (stirring time) is changed from 45 minutes to 240 minutes.

[Evaluation method]
The evaluation method of each sample (toners A to Q) is as follows.

(Bubble ratio in shell layer)
The toner base particles of each sample (toners A to Q) were extracted before external addition, and the extracted toner base particles were dispersed in a photocurable resin. Thereafter, the photocurable resin was irradiated with ultraviolet rays to cure the resin. Subsequently, the cured product was cut and the cut surface of the cured product was polished. The polished cross section was photographed using a field emission transmission electron microscope (TEM) (“JEM-2100F” manufactured by JEOL Ltd.) (for example, see FIG. 2). 100 toner mother particles were randomly selected from the TEM photograph thus taken, and the TEM photograph was analyzed using image analysis software ("WinROOF" and other image analysis software manufactured by Mitani Corporation). By this image analysis, the ratio of the bubble diameter represented by the following formula (ratio of the average diameter of the bubbles 12a to the average thickness of the shell layer 12) and the ratio of the bubble area (the occupied area of the bubbles 12a to the area of the shell layer 12) Ratio).

Ratio of bubble diameter = average diameter of bubbles 12a / average thickness of shell layer 12 Ratio of bubble area = occupied area of bubbles 12a / area of shell layer 12

  For each of the 100 toner base particles, the bubble diameter ratio and the bubble area ratio were calculated. And the average of the calculated 100 values was used as the evaluation value.

  The average thickness of the shell layer 12 was measured by analyzing the TEM image using image analysis software (“WinROOF” manufactured by Mitani Corporation). Specifically, two straight lines orthogonal to each other at the approximate center of the cross section of the toner base particles were drawn, and the lengths of four locations on the two straight lines intersecting the shell layer 12 were measured. Then, the average value of the four measured lengths was defined as the average thickness of the shell layer 12 of one toner base particle as a measurement target.

  In addition, when the thickness of the shell layer 12 is small, the boundary between the core 11 and the shell layer 12 on the TEM image becomes unclear, and thus the thickness of the shell layer 12 may be difficult to measure. . In such a case, the thickness of the shell layer 12 was measured by combining TEM imaging and electron energy loss spectroscopy (EELS) to clarify the boundary between the core 11 and the shell layer 12. Specifically, in the TEM image, mapping of an element (for example, nitrogen element) contained in the shell layer 12 was performed using EELS.

(Offset evaluation)
A color printer (“FS-C5300DN” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. A developer carrier (FS-C5300DN carrier) and a sample (toner) of 10% by mass with respect to the mass of the carrier were mixed for 30 minutes using a ball mill to prepare a two-component developer. The prepared developer was put into a cyan developing device of an evaluation machine, and a sample (toner) was put into a cyan toner container of the evaluation machine.

Using an evaluation machine, a solid image having a printing rate of 100% was formed on a recording medium. The amount of applied toner was adjusted between 1.4 mg / cm ^{2 and} 1.5 mg / cm ² . Then, the fixing temperature of the evaluation machine was changed from 120 ° C. to 180 ° C. to evaluate the offset resistance. The presence or absence of occurrence of offset was confirmed visually.

  If no offset was generated, it was evaluated as ◯ (good). If the offset was small, it was evaluated as Δ (somewhat inferior). If the offset was large, it was evaluated as x (not good).

(Heat resistant storage stability)
5 g of a sample (toner) was put in a glass sample bottle, and the sample bottle was allowed to stand for 24 hours in a constant temperature bath (“DKN302” manufactured by Yamato Scientific Co., Ltd.) set at a temperature of 55 ° C. Then, the sample bottle was taken out from the thermostat and cooled to room temperature. Subsequently, the toner was sieved using a powder tester manufactured by Hosokawa Micron Co., Ltd. under the condition of the vibration scale 5. A 400 mesh sieve was used for sieving. The toner passing rate was calculated based on the following formula.
Toner passing rate (mass%) = 100 × mass of toner passing through sieve (g) / 5

  When the toner passing rate is 80% by mass or more, it is evaluated as ◯ (good), and when the toner passing rate is 70% by mass or more and less than 80% by mass, it is evaluated as Δ (somewhat inferior), and the toner passing rate is 70% by mass. If it was less than, it was evaluated as x (not good).

[Evaluation results]
Table 1 summarizes the results of evaluating the ratio of the bubbles 12a in the shell layer 12 for the toners A to Q.

  In each of toners A to H, the bubble diameter ratio was 0.3 or more and 0.5 or less, and the bubble area ratio was 0.1 or more and 0.3 or less.

  In Toner I, the ratio of the bubble diameter was 0.3 or more and 0.5 or less, and the ratio of the bubble area was larger than 0.3.

  In Toner J, the bubble diameter ratio was 0.3 or more and 0.5 or less, and the bubble area ratio was less than 0.1.

  In Toner K, the bubble diameter ratio was larger than 0.5, and the bubble area ratio was 0.1 or more and 0.3 or less.

  In the toner L, the bubble diameter ratio was smaller than 0.3 and the bubble area ratio was 0.1 or more and 0.3 or less.

  In the toner M, the ratio of the bubble diameter was smaller than 0.3 and the ratio of the bubble area was less than 0.1.

  In the toner N, the bubble diameter ratio was smaller than 0.3 and the bubble area ratio was larger than 0.3.

  In each of toners O and P, the ratio of the bubble diameter was 0.3 or more and 0.5 or less, and the ratio of the bubble area was larger than 0.3.

  In the toner Q, the presence of bubbles 12a in the shell layer 12 could not be confirmed.

  Hereinafter, the evaluation results shown in Table 1 will be considered with reference to FIGS. 5 and 6. FIG. 5 is a graph showing the relationship between the stirring speed (dispersion blade rotation speed) and the ratio of the bubble diameter in the toner A to Q preparation method. FIG. 6 is a graph showing the relationship between the defoaming time (stirring time) and the ratio of the bubble area in the method for preparing toners A to Q.

  As shown in Table 1 and FIG. 5, the bubble diameter ratio decreased as the stirring speed (dispersion blade rotation speed) increased. The correlation coefficient was 0.702.

  As shown in Table 1 and FIG. 6, the ratio of the bubble area decreased as the defoaming time (stirring time) increased. The correlation coefficient was 0.748.

  Table 2 summarizes the results of evaluating the fixability and heat-resistant storage stability of the toners A to Q.

  In each of toners A to H and K, no offset occurred at a fixing temperature of 120 ° C. or higher and 180 ° C. or lower.

  For toners I, N, O, and P, offset occurred at a fixing temperature of 170 ° C. or higher.

  For toners J, L, and M, offset occurred at a fixing temperature of 130 ° C. or less.

  In toner Q, offset occurred at a fixing temperature of 150 ° C. or lower.

  If the ratio of the bubble area is too large or too small, it is considered that the maximum fixable temperature decreases or the minimum fixable temperature increases (fixability decreases).

  In each of toners A to J, L, M, and O to Q, the toner passing rate was 80% by mass or more.

  With toner K, the toner passing rate was less than 70% by mass.

  With toner N, the toner passing rate was 70% by mass or more and less than 80% by mass.

  When the evaluation results shown in Table 2 are examined, it is considered that the heat resistant storage stability is lowered when the ratio of the bubble diameter is too large or too small. The reason is considered to be that the uniformity of the shell layer 12 is lowered.

  As described above, in each of the toners A to H, the shell layer 12 contained the bubbles 12a. In each of the toners A to H, in the cross section of the shell layer 12, the ratio of the average diameter of the bubbles 12a to the average thickness of the shell layer 12 (the ratio of the bubble diameter) was 0.3 or more and 0.5 or less. In each of the toners A to H, in the cross section of the shell layer 12, the ratio of the area occupied by the bubbles 12a to the area of the shell layer 12 (the ratio of the bubble area) was 0.1 or more and 0.3 or less.

  In each of toners A to H, no offset occurred at a fixing temperature of 120 ° C. or higher and 180 ° C. or lower. In each of the toners A to H, the toner passing rate was 80% by mass or more. Each of the toners A to H was excellent in both fixability and heat resistant storage stability.

  The preparation methods of the toners A to H are respectively the step of forming the core 11, the step of putting the material of the core 11 and the shell layer 12 in the liquid, the step of defoaming by stirring the liquid, and the defoamed liquid To form a shell layer 12 on the surface of the core 11. According to such a method, it is considered that the shell layer 12 containing the bubbles 12a can be easily and appropriately formed on the surface of the core 11.

  In each of the methods for preparing the toners A to H, by controlling the rotation speed of the stirring in the defoaming step in the range of 1100 rpm to 1300 rpm, the ratio of the bubble diameter in the cross section of the shell layer 12 after formation is 0.3 or more. Adjusted to 0.5 or less. According to such a method, the ratio of the bubble diameter (the average diameter of the bubbles 12a / the average thickness of the shell layer 12) can be easily and appropriately adjusted to a desired range (0.3 or more and 0.5 or less). It is considered to be.

  In each of the preparation methods of the toners A to H, by controlling the stirring time in the defoaming step in a range of 30 minutes to 100 minutes, the ratio of the bubble area in the cross section of the shell layer 12 after the formation is 0.1 or more. Adjusted to 0.3 or less. According to such a method, it is considered that the ratio of the bubble area (occupied area of the bubbles 12a / area of the shell layer 12) can be easily and appropriately adjusted to a desired range (0.1 or more and 0.3 or less). It is done.

  In each of the preparation methods of the toners A to H, stirring was performed in an environment having a gauge pressure of −0.100 MPa to −0.085 MPa. It is considered that defoaming can be promoted by performing defoaming in a reduced pressure environment close to vacuum.

The present invention is not limited to the above embodiments.
When the shell layer contains bubbles in the toner, the strength (or fragility) of the shell layer can be easily adjusted. As a result, it is possible to provide a toner excellent in both storability and fixability.

  The toner manufacturing method includes a step of forming a core, a step of putting the core and shell layer materials into the liquid, a step of stirring and defoaming the liquid, and heating the defoamed liquid to The step of forming a shell layer on the surface of the core layer 12 makes it possible to easily and appropriately form the shell layer 12 containing the bubbles 12a on the surface of the core.

  The toner according to the present invention can be used for forming an image in, for example, a copying machine or a printer.

DESCRIPTION OF SYMBOLS 10 Toner particle 11 Core 11a Binder resin 11b Internal additive 12 Shell layer 12a Air bubble 13 External additive

Claims (5)

Forming a core;
Placing the core and shell layer material in a liquid;
Stirring and degassing the liquid;
Heating the defoamed liquid to form the shell layer on the surface of the core;
Only including,
By controlling the rotational speed of stirring in the defoaming step in a range of 1100 rpm to 1300 rpm, the average diameter of the bubbles in the shell layer with respect to the average thickness of the shell layer in the cross section of the shell layer after the formation A method for producing toner, wherein the ratio is adjusted to 0.3 or more and 0.5 or less . By controlling the stirring time in the defoaming step in the range of 30 minutes to 100 minutes, the ratio of the occupied area of bubbles in the shell layer to the area of the shell layer in the cross section of the shell layer after the formation is The toner production method according to claim 1 , wherein the toner is adjusted to 0.1 or more and 0.3 or less. Forming a core;
Placing the core and shell layer material in a liquid;
Stirring and degassing the liquid;
Heating the defoamed liquid to form the shell layer on the surface of the core;
Only including,
By controlling the stirring time in the defoaming step in the range of 30 minutes to 100 minutes, the ratio of the occupied area of bubbles in the shell layer to the area of the shell layer in the cross section of the shell layer after the formation is A method for producing a toner, which is adjusted to 0.1 or more and 0.3 or less . The stirring is gauge pressure is carried out at ambient or less -0.085MPa least -0.100MPa, method for producing a toner according to any one of claims 1-3. Wherein the shell layer comprises a thermosetting resin, method for producing a toner according to any one of claims 1-4.