WO2016121438A1 - 静電潜像現像用トナー及びその製造方法 - Google Patents
静電潜像現像用トナー及びその製造方法 Download PDFInfo
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- WO2016121438A1 WO2016121438A1 PCT/JP2016/050351 JP2016050351W WO2016121438A1 WO 2016121438 A1 WO2016121438 A1 WO 2016121438A1 JP 2016050351 W JP2016050351 W JP 2016050351W WO 2016121438 A1 WO2016121438 A1 WO 2016121438A1
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09307—Encapsulated toner particles specified by the shell material
- G03G9/09314—Macromolecular compounds
- G03G9/09328—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/0825—Developers with toner particles characterised by their structure; characterised by non-homogenuous distribution of components
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/087—Binders for toner particles
- G03G9/08742—Binders for toner particles comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/08755—Polyesters
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09307—Encapsulated toner particles specified by the shell material
- G03G9/09314—Macromolecular compounds
- G03G9/09321—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/0935—Encapsulated toner particles specified by the core material
- G03G9/09357—Macromolecular compounds
- G03G9/09371—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/093—Encapsulated toner particles
- G03G9/09392—Preparation thereof
Definitions
- the present invention relates to an electrostatic latent image developing toner and a method for producing the same.
- a toner that can be satisfactorily fixed without heating the fixing roller as much as possible is desired.
- a binder resin having a low melting point or glass transition point or a release agent having a low melting point is often used for preparing a toner having excellent low-temperature fixability.
- toner particles contained in the toner tend to aggregate.
- the charge amount of the aggregated toner particles tends to be lower than that of other non-aggregated toner particles.
- a toner containing toner particles having a core-shell structure may be used for the purpose of improving the low-temperature fixability, high-temperature stability, and blocking resistance of the toner.
- Patent Document 1 describes a toner containing toner particles in which the surface of a toner core is coated with a thin film containing a thermosetting component, and the softening temperature of the toner core is 40 ° C. or higher and 150 ° C. or lower.
- the toner described in Patent Document 1 uses a hydrophilic thermosetting resin such as melamine.
- the hydrophilic thermosetting resin easily absorbs water molecules under high temperature and high humidity. Furthermore, if melamine or the like is used as a thermosetting resin, free formaldehyde is likely to be generated.
- the present invention has been made in view of the above-described problems, and provides an electrostatic latent image developing toner that is excellent in heat-resistant storage, low-temperature fixability, and charge retention, and that hardly generates free formaldehyde. Objective.
- the electrostatic latent image developing toner of the present invention contains toner particles including a toner core and a shell layer covering the surface of the toner core.
- the shell layer includes a hydrophilic thermosetting resin and a hydrophobic thermoplastic resin.
- the hydrophilic thermosetting resin is a resin containing one or more functional groups selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group.
- the hydrophobic thermoplastic resin is exposed on the surface of the toner particles.
- the method for producing a toner for developing an electrostatic latent image of the present invention includes a toner core production process, a first shell layer forming process, and a second shell layer forming process.
- a toner core is manufactured.
- a hydrophilic thermosetting resin or a precursor thereof, and a hydrophobic thermoplastic resin or a precursor thereof are added to an aqueous medium. Then, the hydrophobic thermoplastic resin or its precursor is adhered to the surface of the toner core in the aqueous medium.
- the aqueous medium is heated to form a shell layer containing the hydrophilic thermosetting resin and the hydrophobic thermoplastic resin on the surface of the toner core.
- the hydrophilic thermosetting resin added in the first shell layer forming step or a precursor thereof is formed from an oxazoline group, a carbodiimide group, and an isocyanate group in the aqueous medium. It becomes the said hydrophilic thermosetting resin containing 1 or more types of functional groups selected from the group which consists of.
- toner for developing an electrostatic latent image that is excellent in heat-resistant storage stability, low-temperature fixability, and charge retention, and further free from formaldehyde.
- FIG. 3 is a diagram illustrating toner particles contained in a toner according to an exemplary embodiment of the present invention.
- 4 is an SEM photograph showing the structure of a shell layer for a toner according to an embodiment of the present invention.
- 4 is an SPM photograph showing the structure of a shell layer for a toner according to an embodiment of the present invention.
- 5 is a TEM photograph of a cross section of a toner particle for a toner according to an exemplary embodiment of the present invention.
- FIG. 4 is an enlarged view showing a shell layer structure of a toner according to an exemplary embodiment of the present invention. It is a figure for demonstrating the shell layer formation process about the manufacturing method of the toner which concerns on embodiment of this invention.
- FIG. 1 is a diagram illustrating toner particles contained in a toner according to an exemplary embodiment of the present invention.
- FIG. 7 is an SEM photograph taken using a scanning electron microscope of the surface of a toner core to which a hydrophilic thermosetting resin precursor and a hydrophobic thermoplastic resin are attached in the process shown in FIG. 6.
- FIG. 7 is an enlarged view showing a part of the surface of a toner core to which a hydrophilic thermosetting resin precursor and a hydrophobic thermoplastic resin are attached in the step shown in FIG. 6.
- the evaluation results (values indicating the shape or physical properties) of the powder are averaged from the powder unless otherwise specified. This is the number average of the values measured for each of the average particles by selecting a significant number of such particles.
- the number average particle diameter of the powder is the number average value of the equivalent circle diameter of primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope unless otherwise specified. It is.
- a compound and its derivatives may be generically named by adding “system” after the compound name.
- the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.
- Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”.
- the toner according to this embodiment is an electrostatic latent image developing toner.
- the toner of the present embodiment is a powder composed of a large number of toner particles.
- the toner according to the exemplary embodiment can be used in, for example, an electrophotographic apparatus (image forming apparatus).
- an electrostatic latent image is formed on the photoconductor based on the image data.
- the formed electrostatic latent image is developed using a two-component developer containing a carrier and toner.
- toner charged by friction with the carrier is attached to the electrostatic latent image to form a toner image on the photoreceptor.
- the toner image on the transfer belt is further transferred to a recording medium (for example, paper). Thereafter, the toner is heated to fix the toner on the recording medium.
- a full color image can be formed by superposing four color toner images of black, yellow, magenta, and cyan.
- the toner according to this embodiment has the following configurations (1) to (3).
- the toner particles include a toner core and a shell layer that covers the surface of the toner core.
- the shell layer includes a hydrophilic thermosetting resin and a hydrophobic thermoplastic resin.
- the hydrophilic thermosetting resin is a resin containing one or more functional groups selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group.
- the hydrophobic thermoplastic resin is exposed on the surface of the toner particles.
- Configuration (1) is useful for achieving both heat-resistant storage stability and low-temperature fixability of the toner. Specifically, it is considered that the heat resistant storage stability of the toner is improved by covering the toner core with the shell layer. In addition, it is considered that the hydrophilic thermosetting resin improves the heat-resistant storage stability of the toner, and the hydrophobic thermoplastic resin improves the low-temperature fixability of the toner.
- Structure (2) is useful for suppressing the generation of free formaldehyde.
- a resin containing one or more functional groups selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group defined in the configuration (2) can be synthesized without using formaldehyde as a raw material. Therefore, it is considered that the resin specified in the configuration (2) can suppress the generation of free formaldehyde more than the amino resin (more specifically, melamine resin or the like).
- the amount of free formaldehyde can be measured, for example, according to JIS standards (JIS K5601-4-1 (2012)).
- the amount of free formaldehyde measured according to the JIS standard (JIS K5601-4-1 (2012)) is preferably 5 ppm or less, more preferably 1 ppm or less, and 0 ppm (or cannot be detected). Is most preferred.
- Structure (3) is useful for suppressing charge attenuation of the toner. Specifically, the exposure of the hydrophobic thermoplastic resin on the surface of the toner particles makes it difficult for moisture to be adsorbed on the surface of the toner particles even under high temperature and high humidity. For this reason, the charge retention of the toner is improved and the charge attenuation of the toner is suppressed.
- the toner according to the present embodiment includes toner particles having all the configurations (1) to (3) (hereinafter referred to as toner particles according to the present embodiment).
- the toner containing the toner particles of the present embodiment is excellent in heat-resistant storage stability, low-temperature fixability, and charge retention, and hardly generates free formaldehyde (see Table 1 described later).
- the toner preferably contains the toner particles of this embodiment in a proportion of 80% by number or more, more preferably contains the toner particles of this embodiment in a proportion of 90% by number or more, and a proportion of 100% by number. More preferably, the toner particles of the present embodiment are included.
- the electrostatic latent image developing toner may have the following configuration (4) in addition to the configurations (1) to (3). preferable.
- a plurality of blocks substantially composed of a hydrophobic thermoplastic resin are connected to each other via a joint portion substantially composed of a hydrophilic thermosetting resin.
- Additives may be dispersed in the hydrophobic thermoplastic resin constituting the block.
- the additive may be disperse
- the quantity of the hydrophobic thermoplastic resin contained in a block is 80 mass% or more with respect to the mass of the whole block, It is more preferable that it is 90 mass%, It is 100 mass%.
- the amount of the hydrophilic thermosetting resin contained in the joint is preferably 80% by mass or more, more preferably 90% by mass, and 100% by mass with respect to the mass of the entire joint. Most preferably it is.
- FIG. 1 shows toner particles contained in the toner according to the present embodiment.
- the toner particles include a toner core 10 and a shell layer 20 that covers the toner core 10.
- the shell layer 20 includes a joint portion 21 and a plurality of blocks 22.
- the joining portion 21 is substantially composed of a hydrophilic thermosetting resin.
- Each of the blocks 22 is substantially composed of a hydrophobic thermoplastic resin.
- a minute block 22 is formed in each region partitioned by the joint portion 21. For example, all the blocks 22 are exposed on the surface of the toner particles.
- the present invention is not limited to this, and some of the blocks 22 may not be exposed on the surface of the toner particles.
- FIG. 2 is an SEM photograph showing the structure of the shell layer defined by the configuration (4).
- FIG. 3 is an SPM photograph showing the structure of the shell layer defined by the configuration (4).
- the surface of the toner particles (shell layer 20) has a sea-island structure.
- a sea island structure as shown in FIGS. 2 and 3 is formed by the block 22 and the joint portion 21.
- FIG. 4 is a TEM photograph showing a cross section of toner particles. Specifically, it is a TEM photograph obtained by photographing a cross section of toner particles having configurations (1) to (4) by electron energy loss spectroscopy (EELS) using a transmission electron microscope (TEM). As shown in FIG. 4, the surface of the toner particles has protrusions of hydrophilic thermosetting resin containing a lot of nitrogen atoms in some places. The hydrophobic thermoplastic resin is distributed so as to fill in between the protrusions. As described above, in the example shown in FIG. 4, the hydrophobic thermoplastic resin is exposed on the surface of the toner particles.
- EELS electron energy loss spectroscopy
- FIG. 5 is an enlarged view of the shell layer 20 shown in FIG.
- the structure of the shell layer 20 will be further described mainly with reference to FIGS. 1 and 5.
- the joint 21 is formed between the block 22 and another block 22.
- Each of the blocks 22 is partitioned by a joint portion 21 (a wall of the joint portion 21) located between the block 22 and the other block 22.
- the joining portion 21 is also formed in the gap between the block 22 and the toner core 10.
- a joint portion 21 (a film of the joint portion 21) located in the gap between the block 22 and the toner core 10 is connected to each of the walls of the joint portion 21 so that the whole joint portion 21 is integrated.
- the junction part 21 may be isolate
- Hydrophobic thermoplastic resins soften when heated above the glass transition point (Tg).
- Tg glass transition point
- the hydrophobic thermoplastic resin (block 22) is partitioned by the hydrophilic thermosetting resin (joining portion 21).
- the toner particles are hardly deformed.
- deformation of the toner particles can be started only when heat and pressure are simultaneously applied to the toner particles.
- aggregation of toner particles is suppressed in a state where no force is applied to the toner. Therefore, the toner having the constitutions (1) to (4) is excellent in both heat storage stability and low-temperature fixability.
- the toner particles include a toner core and a shell layer that covers the surface of the toner core.
- the toner core includes a binder resin.
- the toner particles may contain an optional component (for example, at least one of a colorant, a release agent, a charge control agent, and a magnetic powder) in the binder resin as necessary.
- External toner may be added to the surface of the toner base particles as necessary.
- the toner particles before being treated with the external additive may be referred to as toner mother particles.
- a plurality of shell layers may be laminated on the surface of the toner core.
- the toner may be used as a one-component developer. Further, a two-component developer may be prepared by mixing toner with a desired carrier.
- Toner core (Binder resin)
- the binder resin In the toner core, the binder resin often occupies most of the components (for example, 85% by mass or more). For this reason, it is considered that the properties of the binder resin greatly affect the properties of the entire toner core. For example, when the binder resin has an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group, the toner core tends to become anionic, and the binder resin has an amino group or an amide group. The toner core tends to become cationic.
- the hydroxyl value of the binder resin (measurement method: JIS (Japanese Industrial Standard) K0070-1992) and acid value (measurement method: JIS (Japanese Industrial Standard) K0070-1992)) are each preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more.
- the binder resin is preferably a resin having one or more functional groups selected from the group consisting of an ester group, a hydroxyl group, an ether group, an acid group, and a methyl group, and more preferably a resin having a hydroxyl group and / or a carboxyl group.
- a binder resin having such a functional group easily reacts with a shell material (for example, carbodiimide) to be chemically bonded. When such a chemical bond occurs, the bond between the toner core and the shell layer becomes strong.
- a resin having a functional group containing active hydrogen in the molecule is also preferable.
- the glass transition point (Tg) of the binder resin is preferably not higher than the curing start temperature of the shell material.
- Tg glass transition point
- the Tg of the binder resin can be measured using, for example, a differential scanning calorimeter. More specifically, by measuring the endothermic curve of the sample (binder resin) using a differential scanning calorimeter, the Tg of the binder resin can be obtained from the change point of specific heat in the obtained endothermic curve.
- the softening point (Tm) of the binder resin is preferably 100 ° C. or lower, and more preferably 95 ° C. or lower.
- Tm of the binder resin is 100 ° C. or less, the toner fixability is hardly insufficient even at high-speed fixing.
- the Tm of the binder resin is 100 ° C. or lower, when the shell layer is formed on the surface of the toner core in the aqueous medium, the toner core is likely to be partially softened during the curing reaction of the shell layer. For this reason, the toner core is easily rounded by the surface tension.
- Tm of binder resin can be adjusted by combining multiple types of resin which has different Tm.
- the Tm of the binder resin can be measured using, for example, a Koka type flow tester. More specifically, a sample (binder resin) is set in the Koka flow tester, and the binder resin is melted and discharged under predetermined conditions. Then, the S-curve of the binder resin is measured. The Tm of the binder resin can be read from the obtained S-shaped curve. In the obtained S-curve, if the maximum stroke value is S 1 and the low-temperature baseline stroke value is S 2 , the stroke value in the S-curve is “(S 1 + S 2 ) / 2”. The temperature (° C.) at which corresponds to the Tm of the measurement sample (binder resin).
- thermoplastic resin a thermoplastic resin
- styrene-acrylic acid resins and polyester resins are preferable for improving the dispersibility of the colorant in the toner core, the charging property of the toner, and the fixing property of the toner to the recording medium, respectively.
- the styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers.
- styrenic monomer examples include styrene, ⁇ -methylstyrene, p-hydroxystyrene, m-hydroxystyrene, vinyl toluene, ⁇ -chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, Or p-ethylstyrene is mentioned.
- acrylic acid monomer examples include (meth) acrylic acid, (meth) acrylic acid alkyl ester, and (meth) acrylic acid hydroxyalkyl ester.
- (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic acid n.
- hydroxyalkyl esters of (meth) acrylic acid examples include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, or (meth) acrylic acid 4 -Hydroxybutyl.
- the styrene-acrylic acid resin Hydroxyl groups can be introduced into the.
- the hydroxyl value of the resulting styrene-acrylic acid resin can be adjusted by adjusting the amount of the monomer having a hydroxyl group.
- a carboxyl group can be introduced into the styrene-acrylic acid resin by using an acrylic acid monomer having a carboxyl group.
- the acid value of the resulting styrene-acrylic acid resin can be adjusted by adjusting the amount of (meth) acrylic acid used.
- the number average molecular weight (Mn) of the styrene-acrylic acid resin is 2000 or more and 3000 or less in order to achieve both the strength of the toner core and the fixing property of the toner. Is preferred.
- the molecular weight distribution (the ratio Mw / Mn of the mass average molecular weight (Mw) to the number average molecular weight (Mn)) of the styrene-acrylic acid resin is preferably 10 or more and 20 or less. Gel permeation chromatography can be used to measure Mn and Mw of the styrene-acrylic acid resin.
- the polyester resin can be obtained by polycondensing a divalent or trivalent or higher alcohol and a divalent or trivalent or higher carboxylic acid.
- diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, Examples include 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol.
- suitable bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, or bisphenol A propylene oxide adduct.
- Suitable examples of trihydric or higher alcohols that can be used to prepare the polyester resin 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, Examples include trimethylolpropane or 1,3,5-trihydroxymethylbenzene.
- divalent carboxylic acids that can be used to prepare the polyester resin include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, Adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid Etc.), or alkenyl succinic acid (specifically, n-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid, isododecenyl succinic acid, is
- Preferred examples of the trivalent or higher carboxylic acid that can be used to prepare the polyester resin include 1,2,4-benzenetricarboxylic acid (trimellitic 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, Examples include 4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid.
- trimellitic acid trimellitic acid
- 2,5,7-naphthalenetricarboxylic acid 1
- 2,4-naphthalenetricarboxylic acid 1,2,4-butanetricarboxylic acid
- the above-mentioned alcohol and carboxylic acid may be used singly or in combination of two or more. Furthermore, the above divalent or trivalent or higher carboxylic acid may be derivatized to an ester-forming derivative such as an acid halide, an acid anhydride, or a lower alkyl ester.
- ester-forming derivative such as an acid halide, an acid anhydride, or a lower alkyl ester.
- lower alkyl means an alkyl group having 1 to 6 carbon atoms.
- the acid value and hydroxyl value of the polyester resin can be adjusted by changing the amount of alcohol used and the amount of carboxylic acid used.
- the acid value and hydroxyl value of the polyester resin tend to decrease.
- the number average molecular weight (Mn) of the polyester resin is preferably 1000 or more and 2000 or less in order to achieve both the strength of the toner core and the fixing property of the toner.
- the molecular weight distribution of the polyester resin is preferably 9 or more and 21 or less.
- Gel permeation chromatography can be used for the measurement of Mn and Mw of the polyester resin.
- the toner core may contain a colorant.
- a colorant a known pigment or dye can be used according to the color of the toner.
- the amount of the colorant 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.
- the toner core may contain a black colorant.
- a black colorant is carbon black.
- the black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.
- the toner core may contain a color colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.
- yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, or arylamide compounds.
- Suitable 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), naphthol yellow S, Hansa yellow G, or C.I. I. Bat yellow is mentioned.
- magenta colorants examples include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, or perylene compounds.
- Suitable 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).
- cyan colorants include copper phthalocyanine compounds, anthraquinone compounds, or basic dye lake compounds. Suitable 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.
- the toner core may contain a release agent.
- the release agent is used, for example, for the purpose of improving the fixing property or offset resistance of the toner.
- the amount of the release agent 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. More preferably, it is 20 parts by mass or less.
- Suitable examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidized polyethylene wax or Oxides of aliphatic hydrocarbon waxes such as block copolymers; vegetable waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; such as beeswax, lanolin, or whale wax Animal waxes; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanic ester waxes or castor waxes; deacidified carnauba waxes Part or all of fatty acid esters are de-oxidized waxes.
- fatty acid esters such as montanic ester waxes or castor waxes
- a compatibilizing agent may be added to the toner core.
- the toner core may contain a charge control agent.
- the charge control agent is used, for example, for the purpose of improving the charging stability or charging rising property of the toner. Further, the anionic property of the toner core can be enhanced by including a negatively chargeable charge control agent in the toner core.
- the charge rising characteristic of the toner is an index as to whether or not the toner can be charged to a predetermined charge level in a short time.
- the toner core may contain magnetic powder.
- magnetic powder materials include ferromagnetic metals (more specifically, iron, cobalt, nickel, etc.) or alloys thereof, ferromagnetic metal oxides (more specifically, ferrite, magnetite, or chromium dioxide). Etc.) or a material subjected to a ferromagnetization treatment (more specifically, a heat treatment etc.) can be suitably used.
- One type of magnetic powder may be used alone, or a plurality of types of magnetic powder may be used in combination.
- metal ions for example, iron ions
- a shell layer is formed on the surface of the toner core under acidic conditions, if the metal ions are eluted on the surface of the toner core, the toner cores are easily fixed to each other. By suppressing the elution of metal ions from the magnetic powder, sticking between the toner cores can be suppressed.
- the shell layer includes a hydrophilic thermosetting resin and a hydrophobic thermoplastic resin. For this reason, a shell layer having a uniform thickness is easily formed on the surface of the toner core. Further, by adding a hydrophobic thermoplastic resin to the shell layer in addition to the hydrophilic thermosetting resin, the charge amount of the toner can be easily adjusted to a desired range.
- the amount of the hydrophilic thermosetting resin is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner core.
- the amount of the hydrophobic thermoplastic resin is preferably 30 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the toner core.
- the shell layer may contain a charge control agent (for example, a positively chargeable charge control agent).
- the hydrophobic thermoplastic resin is a functional group (for example, a hydroxyl group, a carboxyl group, an amino group, or the like) that easily reacts with a functional group of a hydrophilic thermosetting resin (specifically, an oxazoline group, a carbodiimide group, or an isocyanate group). It preferably has a carbodiimide group, an oxazoline group, or a glycidyl group.
- the amino group may be contained in the hydrophobic thermoplastic resin as a carbamoyl group (—CONH 2 ).
- the hydrophobic thermoplastic resin preferably contains a repeating unit derived from an acrylic acid monomer.
- the hydrophobic thermoplastic resin preferably contains a repeating unit having an alcoholic hydroxyl group, and the repeating unit derived from 2-HEMA (2-hydroxyethyl methacrylate) is preferably used. It is particularly preferable to include it.
- the ratio of the repeating units having a hydrophilic functional group out of all the repeating units contained in the resin constituting the shell layer is It is preferable that it is 10 mass% or less.
- the hydrophilic functional group is an acid group (more specifically, a carboxyl group or a sulfo group), a hydroxyl group, or a salt thereof (more specifically, —COONa, —SO 3 Na, or —ONa).
- monomers used for including a repeating unit having an alcoholic hydroxyl group in the shell layer include (meth) acrylic acid 2-hydroxyalkyl ester (particularly preferably, 2-hydroxyethyl acrylate (BHEA), acrylic acid 2 -Hydroxypropyl (HPA), 2-hydroxyethyl methacrylate (HEMA), or 2-hydroxypropyl methacrylate).
- the hydrophobic thermoplastic resin examples include acrylic acid resin, styrene-acrylic acid copolymer, silicone-acrylic acid graft copolymer, urethane resin, polyester resin, or ethylene-vinyl alcohol copolymer. Can be mentioned.
- acrylic resin, styrene-acrylic acid copolymer, or silicone-acrylic acid graft copolymer is preferable, and acrylic resin is more preferable.
- the hydrophilic thermosetting resin is a resin containing one or more functional groups selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group (hereinafter referred to as a specific functional group-containing resin).
- the specific functional group-containing resin is preferably at least one resin selected from the group consisting of a polyoxazoline resin, a polycarbodiimide resin, a polyisocyanate resin, and derivatives of these resins, such as 2-isopropenyl-2-oxazoline, One or more selected from the group consisting of 2- (pent-4-ynyl) -2-oxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 1-allyl urea, and derivatives of these monomers A monomer polymer containing the compound is more preferable.
- Each of the oxazoline group, the carbodiimide group, and the isocyanate group easily forms a crosslinked structure (and thus a three-dimensional network structure) in the resin.
- an oxazoline group easily reacts with a carboxyl group to form an amide ester bond.
- a carbodiimide group easily reacts with a carboxyl group to form an N-acyl urea bond.
- an isocyanate group tends to react with a hydroxyl group to form a urethane bond.
- crosslinking hardening function of hydrophilic thermosetting resin can be improved by including nitrogen element in hydrophilic thermosetting resin.
- the shell layer may have a fractured part (a part with weak mechanical strength).
- the broken portion can be formed by causing a defect or the like locally in the shell layer.
- the shell layer can be easily broken. As a result, the toner can be fixed on the recording medium at a low temperature.
- the number of destruction points is arbitrary.
- An external additive may be attached to the surface of the toner particles as necessary.
- the external additive include fine particles of metal oxide (more specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, etc.) or fine particles of silica.
- the particle diameter of the external additive is preferably 0.01 ⁇ m or more and 1.0 ⁇ m or less.
- the amount of the external additive is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner base particles.
- a two-component developer can be prepared by mixing the toner of this embodiment with a carrier.
- a carrier When preparing a two-component developer, it is preferable to use a magnetic carrier.
- carrier particle powder in which a carrier core is coated with a resin.
- carrier cores include iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, or cobalt particles; alloys of these materials with metals such as manganese, zinc, or aluminum Particles of iron-nickel alloy or iron-cobalt alloy; ceramics (more specifically, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, titanium Particles of barium oxide, lithium titanate, lead titanate, lead zirconate, lithium niobate, etc .; high dielectric constant materials (more specifically, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or Rochelle salt) Etc.).
- the carrier core is made of a resin, the particles (for example, ferrite particles) may be dispersed in the resin constituting the carrier core.
- the resin covering the carrier core examples include acrylic acid polymers, styrene polymers, styrene-acrylic acid copolymers, olefin polymers (more specifically, polyethylene, chlorinated polyethylene, or polypropylene). Etc.), polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, urethane resin, epoxy resin, silicone resin, fluorine resin (more specifically, polytetrafluoroethylene, Polychlorotrifluoroethylene or polyvinylidene fluoride), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, or amino resin. Two or more of these resins may be combined.
- the particle diameter of the carrier measured with an electron microscope is preferably 20 ⁇ m or more and 120 ⁇ m or less, and more preferably 25 ⁇ m or more and 80 ⁇ m or less.
- the toner content is preferably 3% by mass or more and 20% by mass or less with respect to the mass of the two-component developer. It is preferable that it is 15 mass% or less.
- the method for producing a toner for developing an electrostatic latent image according to the present embodiment includes a toner core production step, a first shell layer forming step, and a second shell layer forming step.
- a toner core is manufactured.
- a toner core obtained in the toner core manufacturing step, a hydrophilic thermosetting resin or a precursor thereof, and a hydrophobic thermoplastic resin or a precursor thereof are added to an aqueous medium, and an aqueous medium is added.
- a hydrophobic thermoplastic resin or a precursor thereof is attached to the surface of the toner core.
- an aqueous medium containing a shell material a hydrophilic thermosetting resin or a precursor thereof, and a hydrophobic thermoplastic resin or a precursor thereof
- a shell material a hydrophilic thermosetting resin or a precursor thereof, and a hydrophobic thermoplastic resin or a precursor thereof
- a shell layer including a curable resin and a hydrophobic thermoplastic resin is formed.
- the hydrophilic thermosetting resin added in the first shell layer forming step or its precursor is selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group in an aqueous medium. It becomes a hydrophilic thermosetting resin containing one or more selected functional groups.
- Toner core manufacturing process As the toner core manufacturing process, for example, a pulverization method or an aggregation method is preferable.
- a binder resin and an internal additive for example, a colorant, a release agent, a charge control agent, and magnetic powder
- an internal additive for example, a colorant, a release agent, a charge control agent, and magnetic powder
- the obtained mixture is melted and kneaded.
- the obtained kneaded material is pulverized.
- the obtained pulverized product is classified.
- a toner core having a desired particle size can be obtained.
- the toner core can be prepared relatively easily.
- the aggregation method includes, for example, an aggregation process and a coalescence process.
- a plurality of types of fine particles for example, binder resin fine particles, colorant fine particles, and release agent fine particles
- the components contained in the aggregated particles are coalesced in an aqueous medium to form a toner core. According to the aggregation method, it is easy to obtain a toner core having a uniform shape and a uniform particle diameter.
- a shell layer is formed on the surface of the toner core.
- the shell layer is formed using, for example, a hydrophilic thermosetting resin precursor (for example, a monomer or prepolymer of a hydrophilic thermosetting resin) and a hydrophobic thermoplastic resin.
- a hydrophilic thermosetting resin precursor for example, a monomer or prepolymer of a hydrophilic thermosetting resin
- a hydrophobic thermoplastic resin Specifically, the toner core obtained in the toner core manufacturing process, the hydrophilic thermosetting resin precursor, and the hydrophobic thermoplastic resin are added to the aqueous medium.
- the hydrophilic thermosetting resin precursor a compound containing at least one functional group selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group is preferable.
- a hydrophobic thermoplastic resin precursor for example, a prepolymer of a hydrophobic thermoplastic resin
- a hydrophilic thermosetting resin may be added to the aqueous medium instead of the hydrophobic thermoplastic resin.
- the hydrophobic thermoplastic resin does not dissolve in the aqueous medium, but the hydrophilic thermosetting resin dissolves in the aqueous medium.
- the shell layer is preferably formed in an aqueous medium.
- the aqueous medium is a medium containing water as a main component (more specifically, pure water or a mixed liquid of water and a polar medium).
- the aqueous medium may function as a solvent.
- a solute may be dissolved in the aqueous medium.
- the aqueous medium may function as a dispersion medium.
- the dispersoid may be dispersed in the aqueous medium.
- a polar medium in the aqueous medium for example, alcohol (more specifically, methanol or ethanol) can be used.
- the boiling point of the aqueous medium is about 100 ° C.
- FIGS. 6 to 8 each show a state in which a hydrophobic thermoplastic resin is adhered to the surface of the toner core in the toner manufacturing method according to the present embodiment.
- FIG. 7 is an SEM photograph.
- FIG. 8 is a partially enlarged view of FIG.
- the toner core and the shell material hydrophilic thermosetting resin precursor and hydrophobic thermoplastic resin
- the particulate hydrophobic thermoplastic resin is adsorbed on the surface of the toner core in the aqueous medium.
- a hydrophilic thermosetting resin precursor is formed so as to cover the surface of the toner core to which the particulate hydrophobic thermoplastic resin is adhered. More specifically, as shown in FIG. 6, a hydrophilic thermosetting resin precursor film 21a and hydrophobic thermoplastic resin particles 22a are formed on the surface of the toner core. Each of the film 21a and the particles 22a is attached to the surface of the toner core.
- the hydrophobic thermoplastic resin Since the hydrophobic thermoplastic resin has hydrophobicity, it is considered that the hydrophobic thermoplastic resin does not spread in the aqueous medium and aggregates to form the particles 22a.
- a plurality of particles 22a can be confirmed on the surface of the toner core covered with the film 21a. As shown in FIG. 8, it is considered that each of the particles 22a is surrounded by the toner core 10 and the film 21a and is not exposed to the aqueous medium (is hardly in contact with the aqueous medium).
- the temperature of the aqueous medium is raised to a predetermined temperature and maintained at that temperature for a predetermined time.
- the shell material hydrophilic thermosetting resin precursor and hydrophobic thermoplastic resin
- the shell material attached to the surface of the toner core reacts and cures.
- a shell layer is formed on the surface of the toner core, and a dispersion of toner mother particles is obtained.
- the shell material (hydrophobic thermoplastic resin and hydrophilic thermosetting resin precursor) is attached to the toner core. Therefore, even if the shell layer is heated and cured, It is considered that the particles of the hydrophobic thermoplastic resin do not fuse on the surface. Further, since the hydrophilic thermosetting resin precursor before heating has strong hydrophilicity, it is considered to exist at the interface between the aqueous medium and the particles of the hydrophobic thermoplastic resin. However, as the curing reaction of the shell layer proceeds, the hydrophilicity of the hydrophilic thermosetting resin precursor tends to weaken. For this reason, during the curing reaction of the shell layer, the hydrophilic thermosetting resin precursor is caused by the capillary effect between the hydrophobic thermoplastic resin blocks and between the hydrophobic thermoplastic resin block and the toner core. It is thought to move.
- Examples of a method for satisfactorily dispersing the toner core in the aqueous medium include a method in which the toner core is mechanically dispersed in the aqueous medium using an apparatus capable of strongly stirring the dispersion.
- the pH of the aqueous medium is preferably adjusted to about 4 using an acidic substance before adding the material for forming the shell layer.
- the reaction for forming the shell layer is promoted by adjusting the pH of the aqueous medium to the acidic side.
- the temperature at which the shell layer is formed on the surface of the toner core is preferably 40 ° C. or more and 95 ° C. or less, more preferably 50 ° C. or more and 80 ° C. or less. preferable.
- the dispersion containing the toner base particles is cooled to room temperature. Thereafter, if necessary, a step of cleaning the toner base particles (cleaning step), a step of drying the toner base particles (drying step), and a step of attaching an external additive to the surface of the toner base particles (external addition step) Through this process, a toner is obtained.
- the toner base particles are washed with water.
- a cleaning method a method of recovering wet cake-like toner mother particles from a dispersion containing toner mother particles by solid-liquid separation, and washing the obtained wet cake-like toner mother particles with water. And a method in which the toner base particles in the dispersion liquid are settled, the supernatant liquid is replaced with water, and the toner base particles are re-dispersed in water after the replacement.
- the toner base particles are dried.
- suitable methods for drying the toner base particles include a method using a dryer (more specifically, a spray dryer, a fluidized bed dryer, a vacuum freeze dryer, a vacuum dryer, or the like).
- a method using a spray dryer is preferable.
- the external additive can be adhered to the surface of the toner base particles by spraying a dispersion of the external additive such as silica onto the toner base particles.
- an external additive is attached to the surface of the toner base particles.
- a mixer more specifically, an FM mixer or a Nauter mixer (registered trademark) is used under such a condition that the external additive is not buried in the surface of the toner base particles.
- Etc. a method of mixing the toner base particles and the external additive.
- the toner manufacturing method can be arbitrarily changed according to the required configuration or characteristics of the toner.
- the toner core may be added to the solvent.
- the material of the shell layer may be dissolved in the solvent.
- the method for forming the shell layer is arbitrary.
- the shell layer may be formed by using any of an in-situ polymerization method, a submerged cured coating method, and a coacervation method. Further, unnecessary steps may be omitted.
- the external additive is not attached to the surface of the toner base particles (the step of external addition is omitted), the toner base particles correspond to the toner particles. In order to produce the toner efficiently, it is preferable to form a large number of toner particles simultaneously.
- Table 1 shows toners of Examples 1 to 9 and Comparative Examples 1 to 4 (each toner for developing an electrostatic latent image).
- thermoplastic resin fine particles I Preparation of thermoplastic resin fine particles I
- ion-exchanged water 875 mL of ion-exchanged water and 75 mL of an anionic surfactant (“Latemul WX” manufactured by Kao Corporation, polyoxyethylene alkyl ether sulfate sodium salt) were placed. Thereafter, the temperature inside the flask was raised to 80 ° C. using a water bath.
- anionic surfactant (“Latemul WX” manufactured by Kao Corporation, polyoxyethylene alkyl ether sulfate sodium salt
- thermoplastic resin fine particles I having hydrophobicity (solid content concentration 2 mass%) was obtained.
- the obtained thermoplastic resin fine particles I were observed with a transmission electron microscope, and it was confirmed that the number average particle diameter was 32 nm.
- the Tg of the thermoplastic resin fine particles I was 71 ° C. as measured by a differential scanning calorimeter.
- thermoplastic resin fine particles II A suspension of the thermoplastic resin fine particles II having hydrophobicity (solid content concentration 2% by mass) was prepared in the same manner as the thermoplastic resin fine particles I except that the addition amount of the anionic surfactant was changed from 75 mL to 25 mL. .
- the obtained thermoplastic resin fine particles II were observed with a transmission electron microscope, and it was confirmed that the number average particle diameter was 107 nm.
- the Tg of the thermoplastic resin fine particles II was 68 ° C. as measured by a differential scanning calorimeter.
- thermoplastic resin fine particles III The suspension of the thermoplastic fine particle III having hydrophobicity (solid content concentration: 10 mass) is the same as the thermoplastic fine particle I except that butyl acrylate is not added and the addition amount of styrene is changed from 17 mL to 100 mL. %).
- the obtained thermoplastic resin fine particles III were observed with a transmission electron microscope, and it was confirmed that the number average particle diameter was 30 nm.
- the Tg of the thermoplastic resin fine particles III was 103 ° C. as measured by a differential scanning calorimeter.
- the obtained kneaded product was cooled and then coarsely pulverized with a pulverizer (“Rotoplex (registered trademark)” manufactured by Hosokawa Micron Corporation).
- a pulverizer (“Rotoplex (registered trademark)” manufactured by Hosokawa Micron Corporation).
- the obtained coarsely pulverized product was finely pulverized with a jet mill (“Ultrasonic Jet Mill I Type” manufactured by Nippon Pneumatic Industry Co., Ltd.).
- the obtained finely pulverized product was classified by a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.). As a result, a toner core was obtained.
- the wet cake-like toner base particles obtained in the washing step were dispersed in an aqueous ethanol solution having a concentration of 50% by mass to prepare a slurry.
- the obtained slurry was supplied to a continuous surface reforming apparatus (“Coatmizer (registered trademark)” manufactured by Freund Sangyo Co., Ltd.) to dry the toner base particles in the slurry to obtain toner base particles. Drying conditions were a hot air temperature of 45 ° C. and a blower air volume of 2 m 3 / min.
- Example 1 100 parts by mass of toner base particles obtained in the drying step and 1.0 part by mass of dry silica (“AEROSIL (registered trademark) REA90” manufactured by Nippon Aerosil Co., Ltd.) are mixed with an FM mixer (Nippon Coke Industries, Ltd.) having a capacity of 10 L. For 5 minutes to adhere the external additive to the surface of the toner base particles. Thereafter, the obtained toner was sieved with a 200 mesh (aperture 75 ⁇ m) sieve to obtain the toner of Example 1.
- AEROSIL registered trademark
- FM mixer Neippon Coke Industries, Ltd.
- Example 2 The toner of Example 2 was obtained in the same manner as the toner of Example 1, except that in the shell layer forming step, 15 mL of the suspension of thermoplastic resin particles II was added instead of 15 mL of the suspension of thermoplastic resin particles I.
- Example 3 The toner of Example 3 was obtained in the same manner as the toner of Example 1, except that in the shell layer forming step, 15 mL of the suspension of thermoplastic resin particles III was added instead of 15 mL of the suspension of thermoplastic resin particles I.
- Example 4 In the shell layer forming step, a carbodiimide group-containing polymer aqueous solution (Nisshinbo Chemical Co., Ltd., “Carbodilite (registered trademark) V-02”, solid content concentration instead of 3.15 g of the oxazoline group-containing polymer aqueous solution as a raw material for the shell layer:
- the toner of Example 4 was obtained in the same manner as the toner of Example 1, except that 2.00 g) was added.
- Example 5 In the shell layer forming step, an isocyanate group-containing polymer aqueous solution (“Elastrone (registered trademark) H-38” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. A toner of Example 5 was obtained in the same manner as the toner of Example 1, except that 4.00 g was added.
- Elastrone (registered trademark) H-38 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
- a toner of Example 5 was obtained in the same manner as the toner of Example 1, except that 4.00 g was added.
- Example 6 The toner of Example 6 was obtained in the same manner as the toner of Example 1, except that the addition amount of the aqueous oxazoline group-containing polymer solution was changed from 3.15 g to 5.00 g in the shell layer forming step.
- Example 7 The toner of Example 7 was obtained in the same manner as the toner of Example 1, except that in the shell layer forming step, the amount of the oxazoline group-containing polymer aqueous solution added was changed from 3.15 g to 2.00 g.
- Example 8 The toner of Example 8 was obtained in the same manner as the toner of Example 1, except that the addition amount of the suspension of the thermoplastic resin fine particles I was changed from 15 mL to 30 mL in the shell layer forming step.
- Example 9 The toner of Example 9 was obtained in the same manner as the toner of Example 1, except that the addition amount of the suspension of the thermoplastic resin fine particles I was changed from 15 mL to 10 mL in the shell layer forming step.
- Comparative Example 1 In the shell layer forming step, instead of 3.15 g of the oxazoline group-containing polymer aqueous solution as a raw material for the shell layer, a methylolmelamine aqueous solution (“Milben (registered trademark) Resin SM-607” manufactured by Showa Denko KK, solid content concentration: 80 mass. %) A toner of Comparative Example 1 was obtained in the same manner as the toner of Example 1 except that 0.35 g was added.
- a methylolmelamine aqueous solution (“Milben (registered trademark) Resin SM-607” manufactured by Showa Denko KK, solid content concentration: 80 mass. %)
- a toner of Comparative Example 1 was obtained in the same manner as the toner of Example 1 except that 0.35 g was added.
- Comparative Example 2 In the shell layer forming step, instead of the suspension of the thermoplastic resin fine particles I, the suspension of the hydrophilic thermoplastic resin fine particles IV (“BECKAMINE (registered trademark) A-1” manufactured by DIC Corporation, component: water-soluble polyacrylamide)
- the toner of Comparative Example 2 was obtained in the same manner as the toner of Example 1, except that 27 mL of (solid content concentration: 11% by mass) was added.
- Comparative Example 3 The toner of Comparative Example 3 was obtained in the same manner as the toner of Comparative Example 1, except that the methylolmelamine aqueous solution was not added in the shell layer forming step.
- Comparative Example 4 The toner of Comparative Example 4 was obtained in the same manner as the toner of Example 1, except that the suspension of the thermoplastic resin fine particles I was not added in the shell layer forming step.
- the heat resistant storage stability of the sample (toner) was evaluated according to the following criteria.
- the charge decay constant ⁇ (toner particle charge decay constant) of the toner in the non-added state is determined using a JIS standard (JIS C 61340-2) using an electrostatic diffusivity measuring device (“NS-D100” manufactured by Nano Seeds Co., Ltd.). It was measured by a method according to -1). The method for measuring the charge decay constant of the toner will be described in detail below.
- a sample (toner with no external addition) was put in the measurement cell.
- the measurement cell was a metal cell in which a recess having an inner diameter of 10 mm and a depth of 1 mm was formed.
- the sample was pushed in from above using a slide glass, and the concave portion of the cell was filled with the sample.
- the sample overflowed from the cell was removed by reciprocating the slide glass on the surface of the cell.
- the filling amount of the sample was 0.04 g or more and 0.06 g or less.
- the measurement cell filled with the sample was allowed to stand for 12 hours in an environment of a temperature of 32 ° C. and a humidity of 80% RH.
- the grounded measurement cell was placed in an electrostatic diffusivity measuring device, and ions were supplied to the sample by corona discharge, and the sample was charged under the condition of a charging time of 0.5 seconds.
- finish of corona discharge the surface potential of the sample was measured continuously.
- V V 0 exp ( ⁇ t)”
- the charge decay constant (charge decay rate) ⁇ was calculated.
- V represents the surface potential [V]
- V 0 represents the initial surface potential [V]
- t represents the decay time [second].
- the calculated charge decay constant ⁇ was evaluated according to the following criteria. A (very good): The charge decay constant ⁇ was less than 0.015. ⁇ (Good): The charge decay constant ⁇ was 0.015 or more and less than 0.020. X (Poor): Charge decay constant ⁇ was 0.020 or more.
- a developer carrier (a carrier for “TASKalfa 5550ci” manufactured by Kyocera Document Solutions Co., Ltd.) and a toner of 10% by mass with respect to the mass of the developer carrier are mixed for 30 minutes using a ball mill, and an evaluation developer (Two-component developer) was prepared.
- ⁇ Low temperature fixability> As an evaluation machine, a color printer having a Roller-Roller type heat and pressure type fixing device (nip width 8 mm) (an evaluation machine that can modify the fixing temperature by modifying "FS-C5250DN" manufactured by Kyocera Document Solutions Co., Ltd.) ) was used.
- the developer for evaluation two-component developer prepared as described above was charged into the developing device of the evaluation machine, and the sample (replenishment toner) was charged into the toner container of the evaluation machine.
- the above-mentioned evaluation machine When evaluating the fixability of the sample (toner), the above-mentioned evaluation machine was used, and the linear velocity was 200 mm / second (nip passage time 40 msec), and the toner applied amount was 1.0 mg / cm 2.
- a solid image having a size of 25 mm ⁇ 25 mm and a printing rate of 100% was formed on paper No. 2 (A4 size printing paper).
- the paper on which the image was formed was passed through the fixing device.
- the setting range of the fixing temperature was 100 ° C. or higher and 200 ° C. or lower. Specifically, the fixing temperature of the fixing device was gradually increased from 100 ° C., and the lowest temperature (minimum fixing temperature) at which the toner (solid image) can be fixed on the paper was measured.
- the toner could be fixed in the measurement of the minimum fixing temperature was confirmed by a rubbing test as shown below. Specifically, the paper was folded in half so that the surface on which the image was formed was on the inside, and 10 kg of reciprocating friction was performed on the fold using a 1 kg weight covered with a fabric. Subsequently, the paper was spread and the bent portion of the paper (the portion where the solid image was formed) was observed. Then, the length (peeling length) of toner peeling at the bent portion was measured. The lowest temperature among the fixing temperatures at which the peeling length was less than 1 mm was defined as the lowest fixing temperature. From the obtained minimum fixing temperature, the low-temperature fixing property of the sample (toner) was evaluated according to the following criteria.
- Transfer efficiency 100 ⁇ (mass of consumed toner ⁇ mass of collected toner) / (mass of consumed toner)
- the consumed toner is toner discharged from the toner container among the samples (toner) set in the toner container.
- the collected toner is toner that has not been transferred to the recording medium among consumed toner.
- the transfer efficiency of the sample (toner) was evaluated according to the following criteria.
- the sample (toner) was evaluated for drum resistance.
- the dash mark is an image defect that can be caused by the toner adhering to the surface of the photosensitive drum.
- the amount of free formaldehyde was evaluated according to the following criteria. ⁇ (Good): The amount of free formaldehyde was less than 5 ppm. X (Poor): The amount of free formaldehyde was 5 ppm or more.
- Table 2 shows the evaluation results for the toners of Examples 1 to 9 and Comparative Examples 1 to 4.
- Table 2 shows heat-resistant storage stability (cohesion degree), low-temperature fixability (minimum fixing temperature), charge retention (charge decay constant), drum resistance (presence of drum adhesion), transfer efficiency, and free formaldehyde (free CH The evaluation results for each of the amounts of 2 O) are shown.
- “nd” in Table 2 indicates that free formaldehyde could not be detected (the amount of free formaldehyde was 1 ppm or less).
- the toner according to Examples 1 to 9 was an electrostatic latent image developing toner having the above-described configurations (1) to (3).
- each of the toners according to Examples 1 to 9 includes toner particles including a toner core and a shell layer that covers the surface of the toner core.
- the shell layer contained a hydrophilic thermosetting resin and a hydrophobic thermoplastic resin.
- the hydrophilic thermosetting resin was a resin containing one or more functional groups selected from the group consisting of an oxazoline group, a carbodiimide group, and an isocyanate group. Further, the hydrophobic thermoplastic resin was exposed on the surface of the toner particles (specifically, each toner had the above-described configuration (4)).
- each of the toners according to Examples 1 to 9 was excellent in low-temperature fixability, charge retention, drum adhesion resistance, and transfer efficiency. In each of the toners according to Examples 1 to 9, free formaldehyde was not detected. On the other hand, in the toner according to Comparative Example 1, since methylol melamine was used as the hydrophilic thermosetting resin precursor, free formaldehyde was generated.
- the electrostatic latent image developing toner according to the present invention can be used to form an image in, for example, a multifunction machine, a copying machine, or a printer.
Abstract
Description
(1)トナー粒子が、トナーコアと、トナーコアの表面を被覆するシェル層とを含む。シェル層が、親水性熱硬化性樹脂と疎水性熱可塑性樹脂とを含む。
(2)親水性熱硬化性樹脂が、オキサゾリン基、カルボジイミド基、及びイソシアネート基からなる群から選択される1種以上の官能基を含む樹脂である。
(3)疎水性熱可塑性樹脂がトナー粒子の表面に露出している。
(結着樹脂)
トナーコアにおいては、成分の大部分(例えば、85質量%以上)を結着樹脂が占めることが多い。このため、結着樹脂の性質がトナーコア全体の性質に大きな影響を与えると考えられる。例えば、結着樹脂がエステル基、水酸基、エーテル基、酸基、又はメチル基を有する場合には、トナーコアはアニオン性になる傾向が強くなり、結着樹脂がアミノ基又はアミド基を有する場合には、トナーコアはカチオン性になる傾向が強くなる。結着樹脂が強いアニオン性を有するためには、結着樹脂の水酸基価(測定方法:JIS(日本工業規格)K0070-1992)及び酸価(測定方法:JIS(日本工業規格)K0070-1992)がそれぞれ10mgKOH/g以上であることが好ましく、それぞれ20mgKOH/g以上であることがより好ましい。
トナーコアは、着色剤を含んでいてもよい。着色剤としては、トナーの色に合わせて公知の顔料又は染料を用いることができる。着色剤の量は、結着樹脂100質量部に対して、1質量部以上20質量部以下であることが好ましく、3質量部以上10質量部以下であることがより好ましい。
トナーコアは、離型剤を含有していてもよい。離型剤は、例えばトナーの定着性又は耐オフセット性を向上させる目的で使用される。トナーコアのアニオン性を強めるためには、アニオン性を有するワックスを用いてトナーコアを作製することが好ましい。トナーの定着性又は耐オフセット性を向上させるためには、離型剤の量は、結着樹脂100質量部に対して、1質量部以上30質量部以下であることが好ましく、5質量部以上20質量部以下であることがより好ましい。
トナーコアは、電荷制御剤を含んでいてもよい。電荷制御剤は、例えばトナーの帯電安定性又は帯電立ち上がり特性を向上させる目的で使用される。また、トナーコアに負帯電性の電荷制御剤を含ませることで、トナーコアのアニオン性を強めることができる。トナーの帯電立ち上がり特性は、短時間で所定の帯電レベルにトナーを帯電可能か否かの指標になる。
トナーコアは、磁性粉を含んでいてもよい。磁性粉の材料としては、例えば、強磁性金属(より具体的には、鉄、コバルト、又はニッケル等)もしくはその合金、強磁性金属酸化物(より具体的には、フェライト、マグネタイト、又は二酸化クロム等)、又は強磁性化処理(より具体的には、熱処理等)が施された材料を好適に使用できる。1種類の磁性粉を単独で使用してもよいし、複数種の磁性粉を併用してもよい。
シェル層は、親水性熱硬化性樹脂と疎水性熱可塑性樹脂とを含む。このため、トナーコアの表面に均一な厚さを有するシェル層が形成され易くなる。また、親水性熱硬化性樹脂に加えて疎水性熱可塑性樹脂をシェル層に含ませることで、トナーの帯電量を所望の範囲に調整し易くなる。耐熱保存性と低温定着性と電荷保持性とに優れるトナーを得るためには、親水性熱硬化性樹脂の量が、トナーコア100質量部に対して0.1質量部以上5質量部以下であり、疎水性熱可塑性樹脂の量が、トナーコア100質量部に対して30質量部以上150質量部以下であることが好ましい。なお、シェル層は、電荷制御剤(例えば、正帯電性の電荷制御剤)を含んでいてもよい。
トナー粒子の表面には、必要に応じて外添剤を付着させてもよい。外添剤としては、金属酸化物(より具体的には、アルミナ、酸化チタン、酸化マグネシウム、酸化亜鉛、チタン酸ストロンチウム、又はチタン酸バリウム等)の微粒子、又はシリカの微粒子が挙げられる。
本実施形態のトナーをキャリアと混合することで、2成分現像剤を調製できる。2成分現像剤を調製する場合、磁性キャリアを用いることが好ましい。
以下、本実施形態に係る静電潜像現像用トナーの製造方法について説明する。本実施形態に係る静電潜像現像用トナーの製造方法は、トナーコア製造工程と、第1シェル層形成工程と、第2シェル層形成工程とを含む。トナーコア製造工程では、トナーコアを製造する。第1シェル層形成工程では、水性媒体に、トナーコア製造工程で得られたトナーコアと、親水性熱硬化性樹脂又はその前駆体と、疎水性熱可塑性樹脂又はその前駆体とを添加して、水性媒体中で、トナーコアの表面に疎水性熱可塑性樹脂又はその前駆体を付着させる。第2シェル層形成工程では、シェル材料(親水性熱硬化性樹脂又はその前駆体、及び疎水性熱可塑性樹脂又はその前駆体)を含む水性媒体を加熱して、トナーコアの表面に、親水性熱硬化性樹脂と疎水性熱可塑性樹脂とを含むシェル層を形成する。また、第2シェル層形成工程では、第1シェル層形成工程で添加された親水性熱硬化性樹脂又はその前駆体が、水性媒体中において、オキサゾリン基、カルボジイミド基、及びイソシアネート基からなる群より選択される1種以上の官能基を含む親水性熱硬化性樹脂になる。
トナーコア製造工程としては、例えば、粉砕法又は凝集法が好ましい。
シェル層形成工程では、トナーコアの表面にシェル層を形成する。シェル層は、例えば、親水性熱硬化性樹脂前駆体(例えば、親水性熱硬化性樹脂のモノマー又はプレポリマー)及び疎水性熱可塑性樹脂を用いて形成される。詳しくは、水性媒体に、トナーコア製造工程で得られたトナーコアと、親水性熱硬化性樹脂前駆体と、疎水性熱可塑性樹脂とを添加する。親水性熱硬化性樹脂前駆体としては、オキサゾリン基、カルボジイミド基、及びイソシアネート基からなる群より選択される1種以上の官能基を含む化合物が好ましい。なお、疎水性熱可塑性樹脂の代わりに疎水性熱可塑性樹脂前駆体(例えば、疎水性熱可塑性樹脂のプレポリマー)を水性媒体に添加してもよい。また、親水性熱硬化性樹脂前駆体の代わりに親水性熱硬化性樹脂を水性媒体に添加してもよい。常温(約25℃)雰囲気では、疎水性熱可塑性樹脂は水性媒体に溶けないが、親水性熱硬化性樹脂は水性媒体に溶ける。
温度計及び攪拌羽根を備えた容量1Lの3つ口フラスコに、イオン交換水875mL及びアニオン界面活性剤(花王株式会社製「ラテムルWX」、ポリオキシエチレンアルキルエーテル硫酸エステルナトリウム塩)75mLを入れた後、ウォーターバスを用いてフラスコ内温を80℃に昇温した。その後、スチレン17mL及びアクリル酸ブチル3mLの混合液、それとは別に過硫酸カリウム0.5gをイオン交換水30mLに溶かした溶液を各々5時間かけてフラスコ内に滴下した。更にフラスコ内容物を80℃で2時間保持して、フラスコ内に添加した重合性モノマーを重合させた。その結果、疎水性を有する熱可塑性樹脂微粒子Iのサスペンション(固形分濃度2質量%)が得られた。得られた熱可塑性樹脂微粒子Iを透過型電子顕微鏡で観察し、数平均粒子径が32nmであることを確認した。また、熱可塑性樹脂微粒子IのTgは、示差走査型熱量計による測定で71℃であった。
アニオン界面活性剤の添加量を75mLから25mLに変更した以外は、熱可塑性樹脂微粒子Iと同様の方法で、疎水性を有する熱可塑性樹脂微粒子IIのサスペンション(固形分濃度2質量%)を作製した。得られた熱可塑性樹脂微粒子IIを透過型電子顕微鏡で観察し、数平均粒子径が107nmであることを確認した。また、熱可塑性樹脂微粒子IIのTgは、示差走査型熱量計による測定で68℃であった。
アクリル酸ブチルを添加せず、スチレンの添加量を17mLから100mLに変更した以外は、熱可塑性樹脂微粒子Iと同様の方法で、疎水性を有する熱可塑性樹脂微粒子IIIのサスペンション(固形分濃度10質量%)を作製した。得られた熱可塑性樹脂微粒子IIIを透過型電子顕微鏡で観察し、数平均粒子径が30nmであることを確認した。また、熱可塑性樹脂微粒子IIIのTgは、示差走査型熱量計による測定で103℃であった。
(トナーコアの作製)
低粘度ポリエステル樹脂(Tg=38℃、Tm=65℃、)750gと、中粘度ポリエステル樹脂(Tg=53℃、Tm=84℃)100gと、高粘度ポリエステル樹脂(Tg=71℃、Tm=120℃)150gと、離型剤(カルナバワックス:株式会社加藤洋行製「カルナウバワックス1号」)55gと、着色剤(フタロシアニンブルー:DIC株式会社製「KET BLUE 111」)40gとを、FMミキサー(日本コークス工業株式会社製)を用いて回転速度2400rpmで混合した。得られた混合物を、二軸押出機(株式会社池貝製「PCM-30」)を用いて、材料投入速度5kg/時、軸回転速度160rpm、設定温度範囲100℃以上130℃以下の条件で溶融混練した。得られた混練物を、冷却した後、粉砕機(ホソカワミクロン株式会社製「ロートプレックス(登録商標)」)で粗粉砕した。次いで、得られた粗粉砕物を、ジェットミル(日本ニューマチック工業株式会社製「超音波ジェットミルI型」)で微粉砕した。続けて、得られた微粉砕物を、分級機(日鉄鉱業株式会社製「エルボージェットEJ-LABO型」)で分級した。その結果、トナーコアが得られた。
温度計及び攪拌羽根を備えた容量1Lの3つ口フラスコに、イオン交換水300mLを入れた後、ウォーターバスを用いてフラスコ内温を30℃に保持した。次いで、フラスコ内に希塩酸を加えて、フラスコ内の水性媒体のpHを4に調整した。pH調整後、フラスコ内に、シェル層の原料として、オキサゾリン基含有高分子水溶液(株式会社日本触媒製「エポクロス(登録商標)WS-700」、固形分濃度:25質量%)3.15gと、熱可塑性樹脂微粒子Iのサスペンション15mLとを添加した。シェル層の原料(特に、オキサゾリン基含有高分子)を水性媒体に溶解させ、シェル層の原料の水溶液を得た。得られた水溶液に、300gのトナーコアを添加し、フラスコの内容物を、回転速度200rpmの速度で1時間攪拌した。次いで、フラスコ内に、イオン交換水300mLを追加した。その後、フラスコの内容物を回転速度100rpmで攪拌しながら、1℃/分の速度で、フラスコ内温を70℃まで上げた。昇温終了後、温度70℃、回転速度100rpmの条件でフラスコの内容物を2時間攪拌し続けた。その後、フラスコ内に、水酸化ナトリウムを加えて、フラスコの内容物のpHを7に調整した。次いで、フラスコの内容物を、常温(約25℃)まで冷却して、トナー母粒子を含む分散液を得た。
ブフナーロートを用いて、トナー母粒子を含む分散液から、ウェットケーキ状のトナー母粒子をろ取した。続けて、ウェットケーキ状のトナー母粒子を再度イオン交換水に分散させてトナー母粒子を洗浄した。こうしたイオン交換水によるトナー母粒子の洗浄を5回繰り返した。
洗浄工程で得られたウェットケーキ状のトナー母粒子を、濃度50質量%のエタノール水溶液に分散させてスラリーを調整した。得られたスラリーを連続式表面改質装置(フロイント産業株式会社製「コートマイザー(登録商標)」)に供給することにより、スラリー中のトナー母粒子を乾燥させてトナー母粒子を得た。乾燥条件は、熱風温度45℃、ブロアー風量2m3/分とした。
乾燥工程で得られたトナー母粒子100質量部と、乾式シリカ(日本アエロジル株式会社製「AEROSIL(登録商標)REA90」)1.0質量部とを、容量10LのFMミキサー(日本コークス工業株式会社製)を用いて5分間混合し、トナー母粒子の表面に外添剤を付着させた。その後、得られたトナーを、200メッシュ(目開き75μm)の篩により篩別して、実施例1のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンション15mLの代わりに熱可塑性樹脂微粒子IIのサスペンション15mLを添加した以外は、実施例1のトナーと同様に実施例2のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンション15mLの代わりに熱可塑性樹脂微粒子IIIのサスペンション15mLを添加した以外は、実施例1のトナーと同様に実施例3のトナーを得た。
シェル層形成工程において、シェル層の原料としてオキサゾリン基含有高分子水溶液3.15gの代わりにカルボジイミド基含有高分子水溶液(日清紡ケミカル株式会社、「カルボジライト(登録商標)V-02」、固形分濃度:40質量%)2.00gを添加した以外は、実施例1のトナーと同様に実施例4のトナーを得た。
シェル層形成工程において、シェル層の原料としてオキサゾリン基含有高分子水溶液3.15gの代わりにイソシアネート基含有高分子水溶液(第一工業製薬株式会社製「エラストロン(登録商標)H-38」、固形分濃度:20質量%)4.00gを添加した以外は、実施例1のトナーと同様に実施例5のトナーを得た。
シェル層形成工程において、オキサゾリン基含有高分子水溶液の添加量を3.15gから5.00gに変更した以外は、実施例1のトナーと同様に実施例6のトナーを得た。
シェル層形成工程において、オキサゾリン基含有高分子水溶液の添加量を3.15gから2.00gに変更した以外は、実施例1のトナーと同様に実施例7のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンションの添加量を15mLから30mLに変更した以外は、実施例1のトナーと同様に実施例8のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンションの添加量を15mLから10mLに変更した以外は、実施例1のトナーと同様に実施例9のトナーを得た。
シェル層形成工程において、シェル層の原料としてオキサゾリン基含有高分子水溶液3.15gの代わりにメチロールメラミン水溶液(昭和電工株式会社製「ミルベン(登録商標)レジンSM-607」、固形分濃度:80質量%)0.35gを添加した以外は、実施例1のトナーと同様に比較例1のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンションの代わりに、親水性を有する熱可塑性樹脂微粒子IVのサスペンション(DIC株式会社製「BECKAMINE(登録商標) A-1」、成分:水溶性ポリアクリルアミド、固形分濃度:11質量%)27mLを添加した以外は、実施例1のトナーと同様に比較例2のトナーを得た。
シェル層形成工程において、メチロールメラミン水溶液を添加しなかったこと以外は、比較例1のトナーと同様に比較例3のトナーを得た。
シェル層形成工程において、熱可塑性樹脂微粒子Iのサスペンションを添加しなかったこと以外は、実施例1のトナーと同様に比較例4のトナーを得た。
各試料(実施例1~9及び比較例1~4のトナー)の評価方法は、以下の通りである。
試料(トナー)2gを容量20mLのポリエチレン製容器に入れて、その容器を、60℃に設定された恒温器内に3時間静置した。その後、恒温器から取り出した容器を冷却することで、容器内に評価用トナーを得た。続けて、評価用トナーを、質量既知の100メッシュ(目開き150μm)の篩に載せた。そして、評価用トナーを含む篩の質量を測定し、篩別前のトナーの質量を求めた。続けて、パウダーテスター(ホソカワミクロン株式会社製)に上記篩をセットし、パウダーテスターのマニュアルに従い、レオスタッド目盛り5の条件で30秒間、篩を振動させ、評価用トナーを篩別した。篩別後、篩を通過しなかったトナー(篩上に残留したトナー)の質量を測定した。篩別前のトナーの質量と、篩別後のトナーの質量(篩を通過しなかったトナーの質量)とから、下記式に従って試料の凝集度(単位:質量%)を算出した。
凝集度(質量%)=100×篩別後のトナーの質量/篩別前のトナーの質量
◎(非常に良い):凝集度が30質量%未満であった。
○(良い):凝集度が30質量%以上50質量%以下であった。
×(良くない):凝集度が50質量%を超えた。
未外添状態でのトナーの電荷減衰定数α(トナー粒子の電荷減衰定数)は、静電気拡散率測定装置(株式会社ナノシーズ製「NS-D100」)を用いて、JIS規格(JIS C 61340-2-1)に準拠した方法で測定した。以下に、トナーの電荷減衰定数の測定方法を詳述する。
◎(非常に良い):電荷減衰定数αが0.015未満であった。
○(良い):電荷減衰定数αが0.015以上0.020未満であった。
×(悪い):電荷減衰定数αが0.020以上であった。
各試料(トナー)の低温定着性、ドラム付着性、及び転写効率を、以下の方法に従って調製した2成分現像剤を用いて評価した。
評価機としては、Roller-Roller方式の加熱加圧型の定着装置(ニップ幅8mm)を有するカラープリンター(京セラドキュメントソリューションズ株式会社製「FS-C5250DN」を改造して定着温度を変更可能にした評価機)を用いた。上記のようにして調製した評価用現像剤(2成分現像剤)を評価機の現像装置に投入し、試料(補給用トナー)を評価機のトナーコンテナに投入した。
◎(非常に良い):最低定着温度が150℃未満であった。
○(良い):最低定着温度が150℃以上160℃未満であった。
×(悪い):最低定着温度が160℃以上であった。
転写効率の評価では、評価機として、カラー複合機(京セラドキュメントソリューションズ株式会社製「TASKalfa5550ci」)を使用した。前述の手順で調製した評価用現像剤(2成分現像剤)を評価機の現像装置に投入し、試料(補給用トナー)を評価機のトナーコンテナに投入した。試料(トナー)を補給しながら、印字率5%の画像を、温度32℃、湿度80%RHの環境下で1万枚の記録媒体(A4サイズの印刷用紙)に連続印刷した。連続印刷中、定期的に目視で感光体ドラムの表面にトナーによる着色が生じたか否かを確認した。また、連続印刷後、消費トナーの質量と回収トナーの質量とを測定して、下記式から転写効率(単位:%)を算出した。
転写効率=100×(消費トナーの質量-回収トナーの質量)/(消費トナーの質量)
◎(非常に良い):転写効率が90%以上であった。
○(良い):転写効率が85%以上90%未満であった。
×(悪い):転写効率が85%未満であった。
○(良い):感光体ドラムの表面にトナーによる着色が観察されず、ソリッド画像にダッシュマークが観察されなかった。
×(悪い):感光体ドラムの表面にトナーによる着色が観察され、ソリッド画像にダッシュマークが観察された。
JIS規格(JIS K5601-4-1(2012))に従い、高速液体クロマトグラフィー(株式会社島津製作所製「LC-2010A HT」)とDNPH誘導体とを用いて、HPLC法にて、測定対象(トナー)中のホルムアルデヒドの量を検出した。測定条件に関しては、カラムのオーブン温度が40℃、測定波長が360nmであった。下記式を用いて、測定対象(トナー)の質量(単位:g)と、検出されたホルムアルデヒドの質量(単位:g)とから、遊離ホルムアルデヒドの量(単位:ppm)を算出した。
遊離ホルムアルデヒドの量=106×検出されたホルムアルデヒドの質量/トナーの質量
○(良い):遊離ホルムアルデヒドの量が5ppm未満であった。
×(悪い):遊離ホルムアルデヒドの量が5ppm以上であった。
実施例1~9及び比較例1~4のトナーの各々についての評価結果を、表2に示す。表2は、耐熱保存性(凝集度)、低温定着性(最低定着温度)、電荷保持性(電荷減衰定数)、耐ドラム付着性(ドラム付着の有無)、転写効率、及び遊離ホルムアルデヒド(遊離CH2O)の量の各々の評価結果を示している。遊離ホルムアルデヒド(遊離CH2O)の量に関しては、表2中の「n.d.」は、遊離ホルムアルデヒドを検出できなかった(遊離ホルムアルデヒドの量が1ppm以下であった)ことを示す。
Claims (7)
- トナーコアと、前記トナーコアの表面を被覆するシェル層とを含むトナー粒子を含有する静電潜像現像用トナーであって、
前記シェル層が、親水性熱硬化性樹脂と疎水性熱可塑性樹脂とを含み、
前記親水性熱硬化性樹脂が、オキサゾリン基、カルボジイミド基、及びイソシアネート基からなる群から選択される1種以上の官能基を含む樹脂であり、
前記疎水性熱可塑性樹脂が前記トナー粒子の表面に露出している、静電潜像現像用トナー。 - 前記シェル層では、実質的に前記疎水性熱可塑性樹脂から構成される複数のブロックが、実質的に前記親水性熱硬化性樹脂から構成される接合部を介して相互に接続されている、請求項1に記載の静電潜像現像用トナー。
- 前記親水性熱硬化性樹脂は、ポリオキサゾリン樹脂、ポリカルボジイミド樹脂、ポリイソシアネート樹脂、及びこれら各樹脂の誘導体からなる群より選択される1種以上の樹脂である、請求項1に記載の静電潜像現像用トナー。
- 前記親水性熱硬化性樹脂は、2-イソプロペニル-2-オキサゾリン、2-(ペンタ-4-イニル)-2-オキサゾリン、アクリル酸2-イソシアナトエチル、メタクリル酸2-イソシアナトエチル、1-アリルウレア、及びこれら各モノマーの誘導体からなる群より選択される1種以上の化合物を含む単量体の重合体である、請求項1に記載の静電潜像現像用トナー。
- 前記親水性熱硬化性樹脂の量は、前記トナーコア100質量部に対して0.1質量部以上5質量部以下であり、
前記疎水性熱可塑性樹脂の量は、前記トナーコア100質量部に対して30質量部以上150質量部以下である、請求項1に記載の静電潜像現像用トナー。 - 前記トナーコアは、ポリエステル樹脂を含む、請求項1に記載の静電潜像現像用トナー。
- トナーコアを製造するトナーコア製造工程と、
前記トナーコア製造工程で得られた前記トナーコアと、親水性熱硬化性樹脂又はその前駆体と、疎水性熱可塑性樹脂又はその前駆体とを水性媒体に添加して、前記水性媒体中で、前記トナーコアの表面に前記疎水性熱可塑性樹脂又はその前駆体を付着させる第1シェル層形成工程と、
前記水性媒体を加熱して、前記トナーコアの表面に、前記親水性熱硬化性樹脂と前記疎水性熱可塑性樹脂とを含むシェル層を形成する第2シェル層形成工程と、
を含み、
前記第2シェル層形成工程では、前記第1シェル層形成工程で添加された親水性熱硬化性樹脂又はその前駆体が、前記水性媒体中において、オキサゾリン基、カルボジイミド基、及びイソシアネート基からなる群から選択される1種以上の官能基を含む前記親水性熱硬化性樹脂になる、静電潜像現像用トナーの製造方法。
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JP2018120055A (ja) * | 2017-01-24 | 2018-08-02 | 京セラドキュメントソリューションズ株式会社 | 静電潜像現像用トナー |
JP2018120118A (ja) * | 2017-01-26 | 2018-08-02 | 京セラドキュメントソリューションズ株式会社 | 静電潜像現像用トナー及びその製造方法 |
JP2018185466A (ja) * | 2017-04-27 | 2018-11-22 | 京セラドキュメントソリューションズ株式会社 | 静電潜像現像用トナー |
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JP2019035909A (ja) * | 2017-08-21 | 2019-03-07 | 京セラドキュメントソリューションズ株式会社 | トナー |
CN109696807A (zh) * | 2017-10-20 | 2019-04-30 | 京瓷办公信息系统株式会社 | 带正电性调色剂及其制造方法 |
JP2019215481A (ja) * | 2018-06-14 | 2019-12-19 | 京セラドキュメントソリューションズ株式会社 | トナー |
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