Electrostatic charge image developing toner, method for producing electrostatic charge image developing toner, image forming method, and image-formed product

Abstract

To provide an electrostatic charge image developing toner or the like in which the blocking phenomenon is reduced.SOLUTION: Provided is an electrostatic charge image developing toner including toner base particles containing a binder resin. The binder resin contains a styrene-(meth)acrylic resin and a polyester. A mass ratio of the styrene-(meth)acrylic resin to the polyester is in a range of 80:20 to 1:99. The electrostatic charge image developing toner is used for forming an image on a recording medium that is long and has an air permeance of 20,000 sec or more at a temperature of 25°C. and a pressure of 49.03 hPa.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a toner for developing electrostatic images, a method for producing a toner for developing electrostatic images, an image forming method, and an image formed product. [Background technology]

[0002] In recent years, the field of electrophotography has seen an increasing diversification of recording media, particularly in label printing and packaging printing using resin films as recording media (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-203964 [Patent Document 2] Japanese Patent Publication No. 2022-054448 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, when the recording medium is long, the recording medium after image formation, i.e., the image-formed product, is wound into a roll for storage and is pulled out when used, and it has been found that a blocking phenomenon, in which toner peels off, is likely to occur when the image-formed product is pulled out from the roll.

[0005] The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide a toner for developing electrostatic images in which the blocking phenomenon is reduced. [Means for solving the problem]

[0006] The present inventors have investigated the causes of the above problems in order to solve the above problems. In a toner for developing electrostatic images, which includes toner base particles containing a binder resin, the binder resin contains a styrene-(meth)acrylic resin and a polyester in a specific mass ratio range. Furthermore, the toner for developing electrostatic images is used to form images on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25°C and a pressure of 49.03 hPa. It has been found that the toner for developing electrostatic images can reduce the blocking phenomenon, leading to the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0007] 1. A toner for developing electrostatic images, comprising toner base particles containing a binder resin, the binder resin contains a styrene-(meth)acrylic resin and a polyester, the mass ratio of the styrene-(meth)acrylic resin to the polyester is within a range of 80:20 to 1:99; Used for forming images on long recording media with an air permeability of 20,000 sec or more at a temperature of 25°C and a pressure of 49.03 hPa. 1. A toner for developing electrostatic images, comprising:

[0008] 2. The styrene-(meth)acrylic resin is located inside the toner base particles, and the polyester is located outside. 2. The toner for developing electrostatic images according to claim 1,

[0009] 3. The polyester is not modified with any compound other than the monomer that forms the repeating unit. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0010] 4. The polyester is not modified with the styrene-(meth)acrylic resin. 4. The toner for developing electrostatic images according to claim 3.

[0011] 5. The styrene-(meth)acrylic resin has a structure derived from methyl methacrylate. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0012] 6. The mass ratio of the styrene-(meth)acrylic resin to the polyester is within the range of 60:40 to 5:95. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0013] 7. The content of the release agent is 7% by mass or less based on the total mass of the toner base particles. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0014] 8. The toner base particles are emulsion aggregates 3. The toner for developing electrostatic images according to claim 1 or 2.

[0015] 9. The loss tangent T(70) at 70°C determined by dynamic viscoelasticity measurement is within the range of 0.2 to 1.2. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0016] 10. The air permeability of the recording medium at a temperature of 25°C and a pressure of 49.03 hPa is 25,000 sec or more. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0017] 11. The recording medium contains at least one of polyethylene, polypropylene, and polyethylene terephthalate. 3. The toner for developing electrostatic images according to claim 1 or 2.

[0018] 12. A method for producing the toner for developing electrostatic images according to item 1 or 2, comprising the steps of: a step of heating a dispersion of styrene-(meth)acrylic resin particles to a temperature T [°C] to grow the particle size; a step of mixing the dispersion of styrene-(meth)acrylic resin particles and the dispersion of polyester particles at a temperature T [°C] while stirring; and maintaining the mixture at a temperature T [°C] for a certain period of time while stirring. The temperature T [°C] is higher than the glass transition temperature of the styrene-(meth)acrylic resin by 30 to 40°C. 1. A method for producing a toner for developing electrostatic images, comprising:

[0019] 13. Using the toner for developing electrostatic images described in item 1 or 2, An image is formed on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25°C and a pressure of 49.03 hPa. An image forming method comprising:

[0020] 14. The image layer on the recording medium contains the toner for developing electrostatic images according to item 1 or 2. An image-formed product characterized by the above-mentioned.

[0021] 15. In a cross section in the thickness direction, the image layer has at least one void in a region having a width of 200 μm. 15. The image-formed product according to item 14, [Effects of the Invention]

[0022] By the above means of the present invention, it is possible to provide a toner for developing electrostatic images in which the blocking phenomenon is reduced.

[0023] Although the mechanism by which the effects of the present invention are manifested or the mechanism of action are not clearly understood, it is speculated as follows: In the following, the "toner for developing electrostatic images" will also be simply referred to as "toner."

[0024] In the case of a long recording medium, the recording medium after image formation, i.e., the image-formed product, is wound up in a roll and stored, and then when the image-formed product is to be used, the image-formed product is pulled out from the roll.

[0025] Fig. 1 is an explanatory diagram of the blocking phenomenon that occurs when an image-formed product is pulled out from a roll 300. Fig. 2 is a cross-sectional view of the image-formed product when the blocking phenomenon occurs. As shown in Figs. 1 and 2, when the image-formed product is pulled out from the roll 300, set-off toner 302 adheres to the surface (back surface) of the recording medium 303 opposite to the surface (front surface) on which the image layer 301 is formed, causing the blocking phenomenon.

[0026] Fig. 3 is a view of an image-formed material wound into a roll, viewed from the center of the roll. When an image-formed material is wound into a roll and stored, an internal force of the roll is applied to the image layer 301, as shown in Fig. 3. This is thought to increase the adhesive force between the recording medium and the image layer 301, making the blocking phenomenon more likely to occur.

[0027] FIG. 4 is an enlarged view of an image-formed material wound into a roll, viewed from the center of the roll. The recording medium 303 wound into a roll is electrostatically charged and positively (+). On the other hand, the image layer 301 tends to be negatively (-) charged. As a result, an electrostatic attraction occurs between the recording medium 303 and the image layer 301, making the blocking phenomenon more likely to occur. Therefore, it is thought that the blocking phenomenon can be reduced by dissipating the negative charge in the image layer to the outside of the image layer and reducing the amount of residual charge.

[0028] In recording media with a relatively low air permeability, i.e., a recording medium with high air permeability, air is less likely to remain between the image layer and the recording medium during image formation, and gaps are less likely to form between the image layer and the recording medium. This makes it difficult for negative charges generated in the image layer to escape to the outside of the image layer, and the amount of residual charge tends to be relatively large. On the other hand, in recording media with a relatively high air permeability, i.e., a recording medium with low air permeability, air is more likely to remain between the image layer and the recording medium during image formation, and gaps are more likely to form between the image layer and the recording medium. This makes it easier for negative charges generated in the image layer to escape through the formed gaps, which is thought to enable the amount of residual charge to be relatively small.

[0029] In the image forming method of this embodiment, a toner containing a specific mass ratio of styrene-(meth)acrylic resin and polyester as binder resins is used. Because polyester has many polar groups, it is easy for the accumulated charge to escape outside the toner, i.e., the charge is easily decayed. However, polyester is inherently prone to negative (-) contact charging with recording media such as resin films. If the contact charge amount is large, even if the charge decays somewhat, the residual charge amount remains large, and the electrostatic attraction between the recording media and the image layer is relatively strong. Therefore, a styrene-(meth)acrylic resin, which is easily positively (+) charged with respect to recording media such as resin films, is used in combination. This reduces the maximum contact charge amount of the toner and makes the residual charge amount relatively small, which is thought to reduce the blocking phenomenon. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is an explanatory diagram of a blocking phenomenon that occurs when an image-formed material is pulled out from a roll. [Figure 2] FIG. 1 is a cross-sectional view of an image-formed product when a blocking phenomenon occurs. [Figure 3] FIG. 2 is a view of an image-formed material wound into a roll as viewed from the center of the roll. [Figure 4] FIG. 2 is an enlarged view of an image-formed material wound into a roll as viewed from the center of the roll. [Figure 5] FIG. 2 is a cross-sectional view of the film label after image formation. [Figure 6] FIG. 2 is a flow diagram of steps (f1) to (f3) in the toner production method. [Figure 7] FIG. 1 is a cross-sectional view of an electrophotographic image forming apparatus. [Figure 8] FIG. 2 is a cross-sectional view of an image-formed product in a thickness direction. DETAILED DESCRIPTION OF THE INVENTION

[0031] The electrostatic image developing toner of the present invention is a toner for developing electrostatic images comprising toner base particles containing a binder resin, wherein the binder resin contains a styrene-(meth)acrylic resin and a polyester, the mass ratio of the styrene-(meth)acrylic resin to the polyester being within a range of 80:20 to 1:99, and the toner is used for forming an image on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25°C and a pressure of 49.03 hPa. This feature is a technical feature common to or corresponding to the following embodiments.

[0032] In an embodiment of the present invention, from the viewpoint of reducing blocking, it is preferable that the styrene-(meth)acrylic resin is located on the inside of the toner base particle and the polyester is located on the outside.

[0033] In an embodiment of the present invention, from the viewpoint of reducing blocking, the polyester is preferably not modified with a compound other than the monomer that forms the repeating unit, and more preferably not modified with a styrene-(meth)acrylic resin.

[0034] In an embodiment of the present invention, from the viewpoint of reducing blocking and improving abrasion resistance, the styrene-(meth)acrylic resin preferably has a structure derived from methyl methacrylate.

[0035] In an embodiment of the present invention, from the viewpoint of reducing blocking, the mass ratio of the styrene-(meth)acrylic resin to the polyester is preferably within the range of 60:40 to 5:95.

[0036] In an embodiment of the present invention, from the viewpoint of reducing blocking, the content of the release agent is preferably 7% by mass or less with respect to the total mass of the toner base particles.

[0037] In an embodiment of the present invention, the toner base particles are preferably emulsion aggregates, from the viewpoint of being able to control the structure and shape of the toner base particles.

[0038] In an embodiment of the present invention, from the viewpoint of reducing blocking and improving low-temperature fixability and abrasion resistance, the loss tangent T(70) at 70° C. determined by dynamic viscoelasticity measurement is preferably within the range of 0.2 to 1.2.

[0039] In an embodiment of the present invention, from the viewpoint of achieving a greater effect in reducing blocking, it is preferable that the air permeability of the recording medium at a temperature of 25° C. and a pressure of 49.03 hPa is 25,000 sec or more.

[0040] In an embodiment of the present invention, from the viewpoint of achieving a greater effect in reducing blocking, it is preferable that the recording medium contains at least one of polyethylene, polypropylene, and polyethylene terephthalate.

[0041] The method for producing a toner for developing electrostatic images of the present invention is a method for producing the above-mentioned toner for developing electrostatic images, and comprises the steps of heating a dispersion of styrene-(meth)acrylic resin particles to a temperature T [°C] to grow particle size, mixing the dispersion of styrene-(meth)acrylic resin particles at temperature T [°C] with a dispersion of polyester particles while stirring, and maintaining the mixture at temperature T [°C] for a certain period of time while stirring, wherein the temperature T [°C] is higher than the glass transition temperature of the styrene-(meth)acrylic resin by a range of 30 to 40°C.

[0042] The image forming method of the present invention is characterized by using the above-mentioned toner for developing electrostatic images.

[0043] The image-formed product of the present invention is characterized in that the image layer on the recording medium contains the above-mentioned toner for developing electrostatic images.

[0044] In an embodiment of the present invention, from the viewpoint of reducing blocking, it is preferable that the image layer has at least one void in a region of width 200 μm in a cross section in the thickness direction.

[0045] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0046] 1. Composition of electrostatic image developing toner The toner for developing electrostatic images of this embodiment has a binder resin containing a styrene-(meth)acrylic resin and a polyester. The mass ratio of the styrene-(meth)acrylic resin to the polyester is within a range of 80:20 to 1:99. The toner for developing electrostatic images of this embodiment is used for forming images on a long recording medium having an air permeability of 20,000 sec or more at 25°C.

[0047] In this specification, toner for developing electrostatic images is also simply referred to as "toner." The toner includes toner base particles. It is preferable that external additives are attached to the surfaces of the toner base particles. Furthermore, "toner base particles" refers to the substance that constitutes the base of "toner particles." "Toner base particles" become "toner particles" when external additives are added. Furthermore, "toner" refers to an aggregate of toner particles.

[0048] (1) Toner base particles The "toner base particles" according to this embodiment preferably contain, in addition to a binder resin, a colorant, a release agent, a charge control agent, and the like, as necessary. The binder resin, the release agent, the colorant, and the charge control agent, which are the components of the toner base particles, will be described below.

[0049] (1.1) Binder resin The toner base particles contain a binder resin, which allows the toner to be fixed onto the recording medium. In this embodiment, the binder resin contains a styrene-(meth)acrylic resin and a polyester resin. The mass ratio of the styrene-(meth)acrylic resin to the polyester resin is within a range of 80:20 to 1:99. The binder resin may contain other resins to the extent that the effects of the present invention are not impaired. The polyester may be a crystalline resin or an amorphous resin.

[0050] Polyester has many polar groups and easily releases the charge in the toner to the outside of the toner. Therefore, it is preferable that the polyester is located on the outside of the toner base particle and the styrene-(meth)acrylic resin is located on the inside. The location of the resin contained in the toner base particle can be confirmed, for example, by observing the cross section of the toner base particle.

[0051] (Method for analyzing resin composition) The composition of each resin contained in the toner base particles can be analyzed by, for example, pyrolysis gas chromatography mass spectrometry (GC / MS). Specifically, the amount can be determined by the standard addition method using a column and a detector that have been confirmed to be capable of detecting a monomer having a specific structure.

[0052] An example of detailed pyrolysis conditions and GC / MS measurement conditions is shown below. (Pyrolysis conditions) Measurement device: PY-2020iD (Frontier Labs, Inc.) Measurement mass: 0.1 mg Heating temperature: 550℃ Heating time: 0.5 minutes

[0053] (GC / MS measurement conditions) Measuring device: QP2010 (Shimadzu Corporation) Column: UltraALLOY-5 (inner diameter: 0.25 mm, length: 30 m, thickness: 0.25 μm, manufactured by Frontier Labs) Temperature range: 40℃ to 320℃ (maintain at 320℃) Heating rate: 20°C / min

[0054] (1.1.1) Amorphous resin In the present invention, "exhibiting amorphousness" means that the material has a glass transition temperature (Tg) but no melting point in an endothermic curve obtained by differential scanning calorimetry (DSC). In other words, it means that there is no clear endothermic peak when the temperature is increased. A clear endothermic peak refers to an endothermic peak with a half-width of 15°C or less in an endothermic curve when the temperature is increased at a rate of 10°C / min.

[0055] In this embodiment, a styrene-(meth)acrylic resin is used as the amorphous resin. The polyester may be amorphous. In addition, known amorphous resins such as vinyl resins other than styrene-(meth)acrylic resins, polybutylene succinate, urethane resins, and urea resins may also be used.

[0056] (1.1.1.1) Styrene-(meth)acrylic resin The styrene-(meth)acrylic resin can be synthesized by addition polymerization of at least (a) a styrene-based monomer and (b) a (meth)acrylic acid ester-based monomer. Examples of the monomer include the following. If necessary, (c) other monomers may also be used.

[0057] (a) Styrene-based monomers In this embodiment, the term "styrene-based monomer" includes not only styrene represented by the structural formula CH2=CH-C6H5, but also monomers having a structure in which a known side chain or functional group is present in the styrene structure. Examples of styrene-based monomers include monomers having a styrene structure, such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and derivatives thereof. These may be contained alone or in combination of two or more.

[0058] (b) (Meth)acrylic acid ester monomer In this embodiment, the term "(meth)acrylic acid ester" refers to at least one of an acrylic acid ester and a methacrylic acid ester. The term "(meth)acrylic acid ester monomer" refers to an acrylic acid ester compound and a methacrylic acid ester compound represented by CH=CHCOOR (R is an alkyl group), as well as an ester compound having a known side chain or functional group in the structure of an acrylic acid ester derivative or a methacrylic acid ester derivative.

[0059] Examples of (meth)acrylic acid ester monomers include monomers having a (meth)acrylic group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and derivatives thereof. These may be contained alone or in combination of two or more.

[0060] Among these, it is preferable to use methyl methacrylate. Methyl methacrylate has a relatively short ester group terminal among (meth)acrylic acid ester monomers, and therefore can reduce the capture of negative charges by the styrene-(meth)acrylic resin. In other words, the amount of residual charge in the toner can be reduced. Furthermore, methyl methacrylate is more resistant to physical impacts than other (meth)acrylic acid ester monomers with relatively short ester group terminals, and therefore the abrasion resistance of the image-formed product is excellent.

[0061] The content of structural units derived from styrene-based monomers in the styrene-(meth)acrylic resin is preferably within a range of 40 to 90% by mass relative to the total mass of the resin, and the content of structural units derived from (meth)acrylic acid ester-based monomers in the resin is preferably within a range of 10 to 60% by mass relative to the total mass of the resin.

[0062] (c) Other Monomers Among the other monomers, examples of monomers having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, etc. Among the other monomers, examples of monomers having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.

[0063] The content of structural units derived from other monomers in the styrene-(meth)acrylic resin is preferably within a range of 0.5 to 20% by mass relative to the total mass of the resin.

[0064] The weight average molecular weight (Mw) of the styrene-(meth)acrylic resin is preferably 10,000 to 100,000.

[0065] The synthesis method of the styrene-(meth)acrylic resin is not particularly limited. Examples of polymerization initiators include peroxides, persulfides, persulfates, azo compounds, etc. Examples of polymerization methods include bulk polymerization, solution polymerization, emulsion polymerization, miniemulsion polymerization, dispersion polymerization, etc. Furthermore, a general chain transfer agent can be used for the purpose of adjusting the molecular weight. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans (e.g., n-octyl mercaptan), mercapto fatty acid esters, etc.

[0066] The glass transition temperature (Tg) of the styrene-(meth)acrylic resin is not particularly limited, but is preferably within the range of 25 to 60°C from the viewpoint of obtaining fixability (low-temperature fixability, etc.) and heat resistance (heat-resistant storage stability, blocking resistance, etc.).

[0067] (1.1.1.2) Amorphous polyester The term "amorphous polyester" refers to a condensation polymer of a polycarboxylic acid (a divalent or higher carboxylic acid) and a polyhydric alcohol (a divalent or higher alcohol), which exhibits amorphous properties. Amorphous polyester can be synthesized by polycondensing (esterifying) the polycarboxylic acid monomer and the polyhydric alcohol monomer using a known esterification catalyst.

[0068] A polycarboxylic acid is a compound containing two or more carboxy groups in one molecule. Examples of polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid, dimethyl isophthalate, fumaric acid, dodecenylsuccinic acid, 1,10-dodecanedicarboxylic acid, etc. Among these, dimethyl isophthalate, terephthalic acid, dodecenylsuccinic acid, and trimellitic acid are preferred. Among these, one kind may be contained alone, or two or more kinds may be contained in combination.

[0069] A polyhydric alcohol is a compound that contains two or more hydroxy groups in one molecule. Examples of polyhydric alcohols include dihydric and trihydric alcohols, such as ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, ethylene oxide adduct of bisphenol A (BPA-EO), propylene oxide adduct of bisphenol A (BPA-PO), glycerin, sorbitol, 1,4-sorbitan, trimethylolpropane, etc. Examples of polyhydric alcohols include ester compounds of these alcohols and hydroxycarboxylic acid derivatives thereof. Among these, one kind may be contained alone, or two or more kinds may be contained in combination.

[0070] In addition, in this embodiment, the "polyhydric alcohol" includes bisphenols because bisphenols can be esterified in the same manner as alcohols.

[0071] Among these, the polyhydric alcohol is preferably an aliphatic polyhydric alcohol. The aliphatic polyhydric alcohol is preferably an aliphatic polyhydric alcohol having 5 or more carbon atoms. By having 5 or more carbon atoms, the number of electrons that can be accepted by the amorphous polyester increases, and it is thought that electrostatic attraction can be suppressed by transferring the generated charges.

[0072] The amorphous polyester is preferably not modified with a compound other than the monomers that form the repeating unit. In other words, it is preferably not modified with a component other than the polycarboxylic acid and polyhydric alcohol that constitute the amorphous polyester. In particular, it is preferably not modified with a styrene-(meth)acrylic resin. This makes it easier for the styrene-(meth)acrylic resins and the polyesters to aggregate together when forming toner base particles, allowing the styrene-(meth)acrylic resin to be located inside the toner base particles and the polyester to be located outside.

[0073] Examples of esterification catalysts for amorphous polyesters include alkali metal compounds (sodium, lithium, etc.), alkaline earth metal compounds (magnesium, calcium, etc.), metal compounds (aluminum, zinc, manganese, antimony, titanium, tin, zirconium, germanium, etc.), phosphorous compounds, phosphoric acid compounds, and amine compounds.

[0074] The polymerization temperature for the amorphous polyester is not particularly limited, but is preferably within a range of, for example, 150 to 250° C. The polymerization time is also not particularly limited, but is preferably within a range of, for example, 0.5 to 10 hours. During the polymerization, the reaction system may be decompressed as necessary.

[0075] The content of the amorphous polyester is preferably within a range of 5 to 50 parts by mass relative to 100 parts by mass of the binder resin, and is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, relative to 100 parts by mass of the toner base particles.

[0076] (1.1.1.3) Glass transition temperature From the viewpoint of achieving both sufficient low-temperature fixability and heat-resistant storage stability, the glass transition temperature (Tg) of the amorphous resin is preferably within a range of 30 to 70°C, and more preferably within a range of 40 to 65°C.

[0077] For example, differential scanning calorimetry (DSC) was performed using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi) and a thermal analyzer controller (AS3 / DX, manufactured by Hitachi). Specifically, 5 mg of sample was placed in a sample container for the AL autosampler (φ6.8 mm, H2.5 mm, manufactured by Hitachi) and a cover for the AL autosampler (manufactured by Hitachi). This was then placed in the sample holder of the AS3 / DX, and the temperature was cycled in the following order: heating, cooling, and heating again. During the first and second heating cycles, the temperature was increased from 0°C to 150°C at a rate of 10°C / min and held at 150°C for 1 minute. During cooling, the temperature was decreased from 150°C to 0°C at a rate of 10°C / min and held at 0°C for 1 minute. A baseline shift was observed in the measurement curve obtained during the second heating cycle. The intersection of the extension of the baseline before the shift and the tangent line showing the maximum slope of the shifted portion of the baseline is taken as the glass transition temperature (Tg). An empty aluminum pan is used as a reference.

[0078] (1.1.1.4) Weight average molecular weight The weight average molecular weight (Mw) of the amorphous resin is not particularly limited, and is preferably within the range of 10,000 to 100,000, for example. The weight average molecular weight of the amorphous resin can be measured in the same manner as the weight average molecular weight of the crystalline resin described below.

[0079] (1.1.2) Crystalline resin By including a crystalline resin, the crystalline portion melts when the temperature exceeds the melting point of the crystalline resin, and the crystalline resin and the amorphous resin become compatible with each other, thereby improving low-temperature fixability.

[0080] In the present invention, "exhibiting crystallinity" means that an endothermic curve obtained by DSC (differential scanning calorimetry) has a clear endothermic peak rather than a stepwise endothermic change at the melting point, i.e., during heating. A clear endothermic peak is a peak with a half-width of 15°C or less in an endothermic curve when heated at a heating rate of 10°C / min.

[0081] As the crystalline resin, it is preferable to use a known crystalline resin, such as a crystalline polyester or a crystalline polyurethane resin. In particular, from the viewpoint of sharp melting during melting and compatibility with the binder resin, a crystalline polyester is preferable.

[0082] (1.1.2.1) Crystalline polyester The term "crystalline polyester" refers to a condensation polymer of a polycarboxylic acid (a divalent or higher carboxylic acid) and a polyhydric alcohol (a divalent or higher alcohol) that exhibits crystallinity.

[0083] Examples of polycarboxylic acids include dicarboxylic acids, such as aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Among them, the polycarboxylic acid is preferably an aliphatic dicarboxylic acid. From the viewpoint of improving crystallinity, the aliphatic dicarboxylic acid is preferably a linear type.

[0084] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, lower alkyl esters thereof, and acid anhydrides thereof. Among these, from the viewpoint of achieving both low-temperature fixability and transferability, aliphatic dicarboxylic acids having 6 to 16 carbon atoms are preferred, and aliphatic dicarboxylic acids having 10 to 14 carbon atoms are more preferred.

[0085] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. Among these, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferred from the viewpoints of availability and ease of emulsification. These may be contained alone or in combination of two or more.

[0086] From the viewpoint of crystallinity, the content of the structural units derived from aliphatic dicarboxylic acids relative to the structural units derived from dicarboxylic acids is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

[0087] The polyhydric alcohol includes a diol, for example, an aliphatic diol, etc. From the viewpoint of enhancing crystallinity, the aliphatic diol is preferably a linear type.

[0088] Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol. Among these, from the viewpoint of achieving both low-temperature fixability and transferability, aliphatic diols having 2 to 12 carbon atoms are preferred, and aliphatic diols having 4 to 6 carbon atoms are more preferred.

[0089] The polyhydric alcohol may contain a diol other than an aliphatic diol. Examples of the other diols include a diol having a double bond and a diol having a sulfonic acid group. Specific examples of the diol having a double bond include 2-butene-1,4-diol, 3-butene-1,6-diol, and 4-butene-1,8-diol.

[0090] The method for synthesizing the crystalline polyester is not particularly limited, and it can be synthesized by polycondensing (esterifying) the polyhydric alcohol component and the polycarboxylic acid component using a known esterification catalyst.

[0091] The ratio of the polyhydric alcohol component to the polycarboxylic acid component is not particularly limited. For example, the equivalent ratio of the hydroxyl groups of the polyhydric alcohol component to the carboxyl groups of the polycarboxylic acid component is preferably within a range of 1.5 / 1 to 1 / 1.5, and more preferably within a range of 1.2 / 1 to 1 / 1.2.

[0092] Catalysts that can be used in the synthesis of crystalline polyesters include alkali metal compounds (sodium, lithium, etc.), alkaline earth metal compounds (magnesium, calcium, etc.), metal compounds (aluminum, zinc, manganese, antimony, titanium, tin, zirconium, germanium, etc.), phosphorous compounds, phosphoric acid compounds, and amine compounds.

[0093] Specific examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof. Examples of titanium compounds include titanium alkoxides (tetra-normal-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, tetrastearyl titanate, etc.), titanium acylates (polyhydroxytitanium stearate, etc.), and titanium chelates (titanium tetraacetylacetonate, titanium lactate, titanium triethanolaminate, etc.).

[0094] Germanium compounds include germanium dioxide. Examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate. These may be used alone or in combination of two or more. The polymerization temperature and polymerization time are not particularly limited, and the pressure in the reaction system may be reduced during the polymerization, if necessary.

[0095] It is preferable that the crystalline polyester is not modified with a compound other than the monomers that form the repeating unit. In other words, it is preferable that the crystalline polyester is not modified with a component other than the polycarboxylic acid and polyhydric alcohol that constitute the crystalline polyester. In particular, it is preferable that the crystalline polyester is not modified with a styrene-(meth)acrylic resin. This makes it easier for the styrene-(meth)acrylic resins and the polyesters to aggregate together when forming toner base particles, and allows the styrene-(meth)acrylic resin to be located inside the toner base particles and the polyester to be located outside.

[0096] (1.1.2.2) Melting Point From the viewpoint of low-temperature fixability and hot offset resistance, the melting point (Tm) of the crystalline resin is preferably within a range of 55 to 90° C., and more preferably within a range of 60 to 85° C. The melting point of the crystalline resin can be controlled by the resin composition. When the crystalline resin is a crystalline polyester, the melting point of the crystalline polyester is preferably 75° C. or lower.

[0097] The melting point (Tm) is the temperature at the top of the endothermic peak, and can be measured by DSC (differential scanning calorimetry). For example, differential scanning calorimetry (DSC) was performed using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi) and a thermal analyzer controller (AS3 / DX, manufactured by Hitachi). Specifically, 5 mg of sample was placed in a sample container for the AL autosampler (φ6.8 mm, H2.5 mm, manufactured by Hitachi) and a cover for the AL autosampler (manufactured by Hitachi). This was then placed in the sample holder of the AS3 / DX, and the temperature was cycled in the following order: heating, cooling, and heating again. During the first and second heating cycles, the temperature was increased from 0°C to 150°C at a rate of 10°C / min and held at 150°C for 1 minute. During cooling, the temperature was decreased from 150°C to 0°C at a rate of 10°C / min and held at 0°C for 1 minute. The melting point was determined as the temperature at the top of the endothermic peak in the endothermic curve obtained during the second heating cycle.

[0098] (1.1.2.3) Weight average molecular weight The weight-average molecular weight of the crystalline resin is not particularly limited, but from the viewpoints of suppressing tacking and low-temperature fixability, it is preferably within a range of 1,000 to 29,000, more preferably within a range of 1,000 to 20,000, and even more preferably within a range of 1,000 to 15,000.

[0099] The weight average molecular weight of the crystalline resin can be measured by the following method. For example, a gel permeation chromatography system "HLC-8320GPC" (manufactured by Tosoh Corporation) is used, which is connected to one column "TSKgel guard column SuperHZ-L" and three columns "TSKgel SuperHZM-M" (all manufactured by Tosoh Corporation).

[0100] The column (TSK-) was stabilized at 40°C, and tetrahydrofuran (THF) was applied as a carrier solvent at a flow rate of 0.35 mL / min. A THF sample solution containing the resin sample, adjusted to a sample concentration of 1 mg / mL, was processed for 10 minutes at room temperature using a roll mill. The solution was filtered through a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μL of this sample solution was injected into the instrument along with the carrier solvent and detected using a refractive index detector (RI detector).

[0101] A calibration curve is created using a polystyrene standard sample with a monodisperse molecular weight distribution. The molecular weight distribution of the measurement sample is calculated based on this calibration curve. The calibration curve is created using "polystylene standard sample TSK standard" manufactured by Tosoh Corporation: "A-500" and "F-1 The data are collected at 300 ms intervals during sample analysis.

[0102] Alternatively, as described below, the crystalline resin and the release agent in the toner may be separated, and then the weight average molecular weight of the crystalline resin may be calculated by the above-mentioned measurement method.

[0103] (Separation of crystalline resin) An example in which the crystalline resin is a crystalline polyester will be described. First, the toner is dispersed in ethanol, which is a poor solvent for the toner, and the resulting dispersion is heated to a temperature exceeding the melting points of the crystalline polyester and the release agent. Pressure may be applied if necessary. At this point, the crystalline polyester and the release agent, which have exceeded their melting points, are melted in the ethanol. Then, a mixture of the crystalline polyester and the release agent can be extracted from the toner by solid-liquid separation. The mixture can be separated by molecular weight to separate the crystalline polyester and the release agent from the toner.

[0104] (Acid value of crystalline resin) From the viewpoint of low temperature fixability and fold fixability, the acid value of the crystalline resin is preferably within a range of 9 to 30 mgKOH / g, and more preferably within a range of 15 to 23 mgKOH / g.

[0105] The acid value of a crystalline polyester is expressed as the number of milligrams of potassium hydroxide required to neutralize the carboxyl groups present in 1 g of the resin (mgKOH / g). Specifically, it is determined by the following method in accordance with JIS K0070-1992.

[0106] (1) Preparation of reagents (a) Phenolphthalein solution 1.0 g of phenolphthalein is dissolved in 90 mL of ethyl alcohol (95% by volume), and ion-exchanged water is added to make the total volume 100 mL to obtain a phenolphthalein solution.

[0107] (b) Potassium hydroxide solution Dissolve 7 g of special-grade potassium hydroxide in 5 mL of ion-exchanged water and add ethyl alcohol (95% by volume) to make 1 L. Place this solution in an alkali-resistant container to avoid contact with carbon dioxide, etc., and leave it for 3 days. Then filter to obtain potassium hydroxide solution. Store the resulting potassium hydroxide solution in an alkali-resistant container.

[0108] (c) Factor of potassium hydroxide solution Place 25 mL of 0.1 mol / L hydrochloric acid in an Erlenmeyer flask and add a few drops of the phenolphthalein solution. Then, titrate this with potassium hydroxide solution. Calculate the potassium hydroxide factor from the amount of potassium hydroxide solution required for neutralization.

[0109] (d) Hydrochloric acid solution 0.1 mol / L hydrochloric acid prepared in accordance with JIS K8001-1998 is used.

[0110] (2) Operation (a) Main test Accurately weigh 2.0 g of toner into a 200 mL Erlenmeyer flask, add 100 mL of a toluene:ethanol (2:1) mixed solution to the Erlenmeyer flask, and dissolve for 5 hours. Next, add a few drops of phenolphthalein solution to the Erlenmeyer flask as an indicator, and titrate with potassium hydroxide solution. The titration endpoint is when the indicator's light red color lasts for approximately 30 seconds.

[0111] (b) Blank test The titration is carried out in the same manner as in the main test above, except that no sample is used, i.e., only a mixture of toluene:ethanol (2:1) is used.

[0112] (3) Substitute the obtained results into the following formula to calculate the acid value. A=[(CD)×f×5.611] / S Here, the symbols and numbers are as follows: A: Acid value (mgKOH / g) C: Amount of potassium hydroxide solution added in this test (mL) D: Amount of potassium hydroxide solution added for blank test (mL) f: Factor of 0.1 mol / L potassium hydroxide ethanol solution 5.611: Molar mass of potassium hydroxide 56.11 (g / mol) × (1 / 10) S: mass of sample (g)

[0113] (1.1.3) Ratio of styrene-(meth)acrylic resin to polyester In the binder resin, the mass ratio of the styrene-(meth)acrylic resin to the polyester is preferably within a range of 80:20 to 1:99, and more preferably within a range of 60:40 to 5:95. A relatively high ratio of polyester makes it easier for electric charges to escape outside the toner, and makes it easier to reduce the blocking phenomenon.

[0114] (1.2) Release agent The release agent is not particularly limited, and various known release agents can be used. For example, polyolefin wax (polyethylene wax, polypropylene wax, etc.), branched chain hydrocarbon wax (microcrystalline wax, etc.), long chain hydrocarbon wax (paraffin wax, Sasol wax, etc.), synthetic wax (Fischer-Tropsch wax, etc.), dialkyl ketone wax (distearyl ketone, etc.), ester wax (carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, distearyl maleate, etc.), amide wax (ethylenediamine behenylamide, tristearyl trimellitate amide, etc.), etc. can be used. These may be contained alone or in combination of two or more.

[0115] Among these, the release agent is preferably a wax with high polarity, that is, an ester wax or an amide wax, since wax with high polarity is easily dispersed in a styrene-(meth)acrylic resin or a polyester.

[0116] The melting point of the release agent is preferably within the range of 60 to 80° C. A melting point of 60° C. or higher can prevent the release agent from volatilizing and breaking down into fine particles during toner fixing, thereby reducing the environmental impact. Furthermore, a melting point of 80° C. or lower allows the release agent to melt during toner fixing, resulting in good separation performance from the fixing member.

[0117] The content of the release agent is preferably 7% by mass or less, more preferably in the range of 3 to 7% by mass, based on the total mass of the toner base particles. By having the content of the release agent within the above range, sufficient fixing and separating properties can be obtained.

[0118] (1.3) Colorants The colorant is not particularly limited, and various known dyes and pigments can be used.

[0119] Examples of colorants contained in the yellow toner include CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162. Examples of colorants include CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, and 185. These may be contained alone or in combination of two or more.

[0120] Examples of colorants contained in the magenta toner include CI Solvent Red 1, 49, 52, 58, 63, 111, and 122. Examples of colorants include CI Pigment Red 5, 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, and 222. These may be contained alone or in combination of two or more.

[0121] An example of a colorant contained in a cyan toner is CI Pigment Blue 15:3.

[0122] Examples of colorants contained in black toner include carbon black, magnetic materials, and titanium black. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of magnetic materials include ferromagnetic metals (iron, nickel, cobalt, etc.), alloys containing ferromagnetic metals, ferromagnetic metal compounds (ferrite, magnetite, etc.), and alloys that do not contain ferromagnetic metals but exhibit ferromagnetism upon heat treatment. Examples of alloys that exhibit ferromagnetism upon heat treatment include Heusler alloys (manganese-copper-aluminum, manganese-copper-tin, etc.) and chromium dioxide.

[0123] The content of the colorant is preferably 1 to 10% by mass, more preferably 4 to 9% by mass, based on the total mass of the toner base particles.

[0124] (1.4) Charge control agent The charge control agent may be any of various known compounds. The content of the charge control agent is preferably within a range of 0.1 to 5.0 parts by mass relative to the total mass of the toner base particles.

[0125] (2) External additives The toner of this exemplary embodiment may further contain an external additive added to the toner base particles, which can further improve the fluidity, chargeability, cleaning properties, and the like of the toner.

[0126] From the viewpoint of controlling fluidity and chargeability, metal oxide particles can be used as an external additive, such as silica particles, titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles. These may be used alone or in combination of two or more.

[0127] As the external additive, organic particles can be used, such as homopolymers of styrene, methyl methacrylate, etc., or copolymers thereof.

[0128] From the viewpoint of improving cleaning properties and transfer properties, lubricants can be used as external additives. Examples of lubricants include metal salts of higher fatty acids such as stearates (zinc, aluminum, copper, magnesium, calcium, etc.), oleates (zinc, manganese, iron, copper, magnesium, etc.), palmitates (zinc, copper, magnesium, calcium, etc.), linoleates (zinc, calcium, etc.), and ricinoleates (zinc, calcium, etc.).

[0129] From the viewpoint of heat-resistant storage property and environmental stability, the film may be subjected to a hydrophobic treatment using a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like.

[0130] The shape of the external additive is not limited, and examples of the shape of the external additive include spherical, flat, plate-like, and needle-like shapes.

[0131] The total amount of external additives added is preferably within a range of 2 to 10 parts by mass, and more preferably within a range of 4 to 7 parts by mass, relative to 100 parts by mass of toner.

[0132] 2. Structure of toner for developing electrostatic images (core-shell structure) The toner base particles may have a multi-layer structure, such as a core-shell structure comprising a core particle and a shell layer covering the surface of the core particle.

[0133] The shell layer does not need to cover the entire surface of the core particle, and the core particle may be partially exposed. The cross section of the core-shell structure can be confirmed by known observation means, for example, a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0134] When the toner base particles have a core-shell structure, the core particles and the shell layer can be differentiated in properties such as glass transition temperature, melting point, and hardness depending on the purpose. For example, core particles containing a binder resin, a colorant, a release agent, etc. and having a relatively low glass transition temperature (Tg) are prepared. Then, a resin with a relatively high glass transition temperature (Tg) is aggregated and fused to the core particles to form a shell layer. The shell layer preferably contains an amorphous resin. This configuration allows for both low-temperature fixability and heat-resistant storage stability. Furthermore, good charge retention performance is obtained.

[0135] In this embodiment, it is preferable that the shell layer contains an amorphous polyester, since it is preferable that the polyester is located on the outer side of the toner base particle.

[0136] 3. Physical properties and shape of toner for developing electrostatic images (1) Toner loss tangent (tanδ) The loss tangent (tan δ) T(70) of the toner at 70° C. in viscoelasticity measurement is preferably within the range of 0.2 to 1.2.

[0137] A loss tangent T(70) of 0.2 or more provides excellent toner fixability. A loss tangent T(70) of 1.2 or less prevents the image layer from adhering to the back surface of the recording medium, even if the image-formed product is wound up and stored before the temperature has completely dropped after fixing, resulting in reduced blocking and excellent abrasion resistance.

[0138] The loss tangent T(70) of the toner can be measured, for example, using a rheometer "ARES G2" (manufactured by TA Instrument Co., Ltd.).

[0139] Specifically, 0.2 g of toner is weighed as a measurement sample, and the weighed toner is pressurized and molded in a compression molding machine at a pressure of 25 MPa to produce cylindrical pellets of each toner with a diameter of 10 mm.

[0140] The temperature of a toner sample is raised from 30°C to 150°C at a rate of 3°C / min, and the storage modulus (G') and loss modulus (G") are measured with increasing temperature. The loss tangent (tanδ) value can be calculated from the relationship (loss modulus / storage modulus) at 70°C.

[0141] The loss tangent T(70) of the toner can be adjusted by the type and content of the components constituting the toner base particles. In particular, it can be adjusted by the structure of the monomers constituting the styrene-(meth)acrylic resin and polyester. It can also be adjusted by the mass ratio of the styrene-(meth)acrylic resin to the polyester. It can also be adjusted by the type of release agent, the dispersibility of the release agent in the toner base particles, etc.

[0142] (2) Glass transition temperature of toner From the viewpoint of achieving both sufficient low-temperature fixability and heat-resistant storage stability, the glass transition temperature (Tg) of the toner is preferably within a range of 15 to 40° C., and more preferably within a range of 20 to 35° C. The glass transition temperature can be measured by the method described above.

[0143] (3) Volume average particle size of toner base particles The volume-average particle size of the toner base particles is, for example, preferably in the range of 3 to 10 μm, more preferably in the range of 4 to 8 μm, in terms of the volume-based median diameter (d50). The volume-average particle size of the toner base particles can be controlled by the concentration of the aggregating agent used in the production of the toner base particles, the amount of organic solvent added, the fusion time, the composition of the binder resin, etc. By having the volume-based median diameter (d50) within the above range, it is possible to faithfully reproduce extremely fine dot images at the 1200 dpi level.

[0144] The volume-based median diameter (d50) of the toner base particles can be measured and calculated using, for example, a measuring device such as a "Multisizer 3" (manufactured by Beckman Coulter) connected to a computer system equipped with data processing software "Software V3.51."

[0145] The measurement procedure involves soaking 0.02 g of a toner sample in 20 mL of surfactant solution, followed by ultrasonic dispersion for 1 minute to prepare a toner base particle dispersion. The surfactant solution can be obtained, for example, by diluting a neutral detergent containing surfactant components 10 times with pure water in order to disperse the toner base particles.

[0146] This toner base particle dispersion is pipetted into a beaker containing "ISOTON II" (manufactured by Beckman Coulter) in the sample stand until the measurement concentration reaches 5-10%. By setting the concentration at this level, highly reproducible measurement values ​​can be obtained.

[0147] The measurement device is set to a particle count of 25,000 and an aperture diameter of 100 μm. The measurement range of toner base particle diameters, 1 to 30 μm, is divided into 256 parts, and the frequency value of the toner base particle diameters is calculated. The particle diameter of the largest 50% of the volume cumulative fraction is taken as the volume-based median diameter (d50).

[0148] (4) Average circularity of toner base particles From the viewpoint of the stability of charging characteristics, fluidity and low-temperature fixability, the average circularity of the toner base particles is preferably 0.945 or more.

[0149] The average circularity of the toner base particles can be measured using, for example, a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation).

[0150] Specifically, the toner sample to be measured is added to a surfactant solution, allowed to settle, diluted with pure water, and then ultrasonically dispersed to prepare a toner base particle dispersion. For the surfactant solution, an anionic surfactant such as sodium polyoxyethylene lauryl ether sulfate is preferably used to disperse the toner base particles. Then, using a flow particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation), for example, images are taken at an appropriate concentration with a HPF (high magnification imaging) mode and an HPF detection count of 3,000 to 10,000 particles.

[0151] The circularity of each toner base particle is calculated according to the following formula: The average circularity is determined by adding up the circularity of each toner base particle and dividing by the total number of toner base particles. If the HPF detection number is within the above range, high reproducibility can be achieved. Formula: Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle's projected image)

[0152] 4. Manufacturing method of toner for developing electrostatic images The method for producing the toner base particles is not particularly limited. Examples of the production method include a kneading and pulverization method, a suspension polymerization method, an emulsion aggregation method, a solution suspension method, a polyester elongation method, a dispersion polymerization method, and other known methods. Among these, the emulsion aggregation method is preferred from the viewpoint of being able to control the internal structure and shape of the particles. That is, the toner base particles according to this embodiment are preferably emulsion aggregates.

[0153] In the emulsion aggregation method, first, an aqueous dispersion of amorphous polyester fine particles is mixed with, as needed, an aqueous dispersion of fine particles of a release agent, a colorant, an amorphous resin other than amorphous polyester, a crystalline resin, etc. Then, these fine particles are aggregated to form wet toner base particles.

[0154] Here, "aqueous dispersion" refers to a dispersion (particles) dispersed in an aqueous medium. In an aqueous medium, the main component, i.e., the component that accounts for 50% by mass or more, is water.

[0155] Components other than water contained in the aqueous medium include water-soluble organic solvents. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol are preferred from the viewpoint of not dissolving the resin.

[0156] An example of a toner manufacturing method is shown below, but is not limited to this. Regarding steps (b) and (c), it is not necessary to perform both steps, and only one of them may be performed. Furthermore, when a resin other than the binder resin is used, a step of preparing a resin particle dispersion may be added.

[0157] (a) A step of synthesizing a styrene-(meth)acrylic resin and preparing a styrene-(meth)acrylic resin particle dispersion liquid (b) A step of synthesizing a crystalline polyester and preparing a crystalline polyester particle dispersion (c) A step of synthesizing an amorphous polyester and preparing an amorphous polyester particle dispersion (d) Step of preparing a release agent particle dispersion (e) Step of preparing a colorant particle dispersion (f) A step of aggregating styrene-(meth)acrylic resin particles, crystalline polyester particles, amorphous polyester particles, release agent particles, and colorant particles to form core particles of toner base particles. (g) A process of aggregating amorphous polyester particles onto the surface of the core particles of the toner base particles to form a shell layer of the toner base particles. (h) A process of fusing and maturing the toner base particles with thermal energy to control the shape. (i) Step of cooling the dispersion of toner base particles (j) A process of filtering the toner base particles from the aqueous medium, washing the toner base particles to remove surfactants, etc., and obtaining wet toner base particles. (k) Step of drying the wet toner base particles (l) A step of adding external additives to the dried toner base particles

[0158] (a) A step of synthesizing a styrene-(meth)acrylic resin and preparing a styrene-(meth)acrylic resin particle dispersion liquid In this step, a styrene-(meth)acrylic resin particle dispersion is prepared by synthesizing a styrene-(meth)acrylic resin and dispersing it in the form of particles in an aqueous medium.

[0159] The synthesized styrene-(meth)acrylic resin is dissolved or dispersed in an organic solvent to prepare an oil phase liquid. The oil phase liquid is then dispersed in an aqueous medium by phase inversion emulsification or the like to form oil droplets with a desired particle size. The organic solvent is then removed to prepare an aqueous dispersion of styrene-(meth)acrylic resin particles.

[0160] The styrene-(meth)acrylic resin particles may have a multilayer structure of two or more layers with different compositions. In this case, a polymerization initiator and a monomer are added to a dispersion liquid prepared by emulsion polymerization (first-stage polymerization), and the system is further polymerized (second-stage polymerization and third-stage polymerization).

[0161] The amount of the aqueous medium used is preferably within a range of 50 to 2,000 parts by mass, and more preferably within a range of 100 to 1,000 parts by mass, per 100 parts by mass of the oil phase liquid. From the viewpoint of dispersion stability of the oil droplets, a surfactant or the like may be added to the aqueous medium. Examples of the surfactant include various conventionally known anionic surfactants, cationic surfactants, nonionic surfactants, etc.

[0162] From the viewpoint of removal treatment after the formation of oil droplets, the organic solvent used for preparing the oil phase liquid is preferably one having a low boiling point and low solubility in water, such as methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene. These may be used alone or in combination of two or more.

[0163] The amount of the organic solvent used is preferably within the range of 1 to 300 parts by mass relative to 100 parts by mass of the styrene-(meth)acrylic resin. The emulsion dispersion of the oil phase liquid can be carried out using mechanical energy.

[0164] If necessary, internal additives such as a release agent and a charge control agent may be dissolved or dispersed in advance in, for example, the monomer solution, thereby allowing the internal additives to be incorporated into the resin particles and ultimately into the toner base particles.

[0165] Specifically, in the synthesis of the styrene-(meth)acrylic resin, it is preferable to add a portion of the release agent to the monomer solution during the second-stage polymerization. In the toner base particles according to this embodiment, the styrene-(meth)acrylic resin is located inside, but by incorporating the release agent into the styrene-(meth)acrylic resin particles, the release agent can be dispersed to some extent inside the toner base particles as well. Furthermore, by adding the release agent during the second-stage polymerization, the release agent can be confined inside the styrene-(meth)acrylic resin particles more easily than when it is added during the third-stage polymerization. By adding the release agent during the second-stage polymerization, the release agent is more likely to seep out of the styrene-(meth)acrylic resin particles when the particles constituting the toner base particles are fused and aged, compared to when it is added during the first-stage polymerization.

[0166] The average particle size of the styrene-(meth)acrylic resin particles is preferably in the range of 100 to 400 nm in terms of volume-based median diameter (d50). The volume-based median diameter (d50) can be measured using, for example, a "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

[0167] (b) A step of synthesizing a crystalline polyester and preparing a crystalline polyester particle dispersion In this step, a crystalline polyester particle dispersion is prepared by synthesizing a crystalline polyester and dispersing it in a particulate form in an aqueous medium. The crystalline polyester particle dispersion can be prepared by the same procedure as for the (a) styrene-(meth)acrylic resin particle dispersion. It is preferable to adjust the temperature during dispersion as necessary.

[0168] (c) A step of synthesizing an amorphous polyester and preparing an amorphous polyester particle dispersion In this step, an amorphous polyester particle dispersion is prepared by synthesizing an amorphous polyester and dispersing it in a particulate form in an aqueous medium. The amorphous polyester particle dispersion can be prepared using the same procedure as for the (a) styrene-(meth)acrylic resin particle dispersion. It is preferable to adjust the temperature during dispersion as necessary.

[0169] (d) Step of preparing a release agent particle dispersion This step is carried out as necessary when a release agent is contained in the toner base particles. The dispersion of release agent particles can be prepared by dispersing the release agent in an aqueous medium to which a surfactant has been added at a critical micelle concentration (CMC) or higher.

[0170] The release agent particle dispersion may contain resin particles from the viewpoint of improving the dispersibility of the release agent particles. The resin particles are not particularly limited, but are preferably particles of a resin used in a binder resin.

[0171] The release agent can be dispersed by utilizing mechanical energy. The dispersing machine is not particularly limited, and examples thereof include an ultrasonic dispersing machine, a mechanical homogenizer, a pressure dispersing machine (such as a Manton-Gaulin or pressure homogenizer), and a medium-type dispersing machine (such as a sand grinder or a diamond fine mill).

[0172] The release agent particles preferably have a volume-based median diameter (d50) in the dispersed state of 10 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm. The volume-based median diameter (d50) of the release agent particles can be measured, for example, using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

[0173] (e) A step of preparing a dispersion of colorant particles The dispersion of colorant particles can be prepared by the same procedure as the dispersion of release agent particles. It is preferable to heat the release agent particles to a temperature equal to or higher than their melting point when dispersing them, but it is not necessary to heat the colorant particles.

[0174] (f) A step of aggregating styrene-(meth)acrylic resin particles, crystalline polyester particles, amorphous polyester particles, release agent particles, and colorant particles to form core particles of toner base particles. In this step, a coagulant at a concentration equal to or greater than the critical coagulation concentration is added to the dispersion liquid in which the above-mentioned particles are dispersed. The temperature of the reaction liquid is adjusted to cause the fine particles to coagulate, forming toner base particles. This step further includes the following steps (f1) to (f3). Figure 6 is a flow diagram of steps (f1) to (f3) in the toner manufacturing method.

[0175] (f1) A step of heating the dispersion of styrene-(meth)acrylic resin particles to a temperature T [°C] to grow the particle size. (f2) A step of mixing the dispersion of styrene-(meth)acrylic resin particles and the dispersion of polyester particles at a temperature T [°C] while stirring. (f3) A process of stirring the mixture and maintaining it at a temperature T [°C] for a certain period of time.

[0176] The temperature T [°C] in steps (f1) to (f3) is higher than the glass transition temperature (Tg) of the styrene-(meth)acrylic resin by 30 to 40°C. By performing steps (f1) to (f3) under the temperature T [°C] condition, the particle size of the styrene-(meth)acrylic resin can be easily grown. Furthermore, the styrene-(meth)acrylic resin can be positioned on the inside and the polyester on the outside of the toner base particles formed.

[0177] The release agent particles and colorant particles are added to the dispersion of styrene-(meth)acrylic resin particles, for example, between the steps (f1) and (f2).

[0178] The polyester in step (f2) may be a crystalline polyester, an amorphous polyester, or both.

[0179] In steps (f1) to (f3), the rotation speed during stirring is not particularly limited, but is preferably within the range of 80 to 330 rpm, which allows the styrene-(meth)acrylic resin to be positioned on the inside and the polyester to be positioned on the outside of the formed toner base particles.

[0180] In the step (f3), the holding time is not particularly limited, but is preferably within a range of 20 to 120 minutes, which allows the styrene-(meth)acrylic resin to be positioned on the inside and the polyester to be positioned on the outside of the formed toner base particles.

[0181] The flocculant is not particularly limited, and is preferably, for example, a metal salt such as an alkali metal salt, an alkaline earth metal salt, etc. Examples of the metal salt include monovalent metal salts (sodium, potassium, lithium, etc.), divalent metal salts (calcium, magnesium, manganese, copper, etc.), and trivalent metal salts (iron, aluminum, etc.).

[0182] Specific examples of metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, etc. Among these, trivalent metal salts are preferred from the viewpoint of promoting aggregation with smaller amounts. These may be used alone or in combination of two or more.

[0183] In the toner base particles according to this embodiment, the polyester is located on the outside, and the release agent particles prepared in the above step (d) are inserted between the crystalline polyester and the amorphous polyester. Therefore, the release agent can be dispersed to some extent on the outside of the toner base particles. In other words, by introducing the release agent into the styrene-(meth)acrylic resin particles and aggregating the release agent particles with each other to form the toner base particles, the release agent can be dispersed uniformly within the toner base particles.

[0184] (g) A process of aggregating amorphous polyester particles onto the surface of the core particles of the toner base particles to form a shell layer of the toner base particles. In this process, a dispersion of amorphous polyester particles is added to a dispersion of core particles of toner base particles. By adjusting the pH, temperature, etc. of the reaction solution, the amorphous polyester particles are aggregated on the surface of the core particles, forming a shell layer of the toner base particles.

[0185] (h) A process of fusing and maturing the toner base particles with thermal energy to control the shape. This step is carried out as necessary when the aggregated particles in the toner base particles are fused and aged by thermal energy to control the shape of the toner base particles. Specifically, in the aging treatment, the dispersion of the toner base particles is heated and stirred by adjusting the heating temperature, stirring speed, heating time, etc. so that the circularity of the toner base particles reaches a desired value.

[0186] (i) Step of cooling the dispersion of toner base particles In this step, the dispersion of toner base particles is cooled. The cooling rate is preferably within the range of 1 to 20°C / min. The specific cooling method is not particularly limited. For example, cooling may be performed by introducing a refrigerant from outside the reaction vessel, by directly adding cold water to the reaction system, or by using a heat exchanger.

[0187] (j) A process of filtering the toner base particles from the aqueous medium, washing the toner base particles to remove surfactants, etc., and obtaining wet toner base particles. In this process, the toner base particles are separated from the cooled dispersion liquid of the toner base particles by solid-liquid separation. The resulting toner cake is then washed to remove any adhering substances such as surfactants and aggregating agents, thereby obtaining wet toner base particles. Note that the term "toner cake" used here refers to a cake-like aggregate of toner base particles in a wet state.

[0188] The method of solid-liquid separation is not particularly limited, and examples thereof include centrifugation, vacuum filtration using a Nutsche filter or the like, and filtration using a filter press or the like. In addition, in washing, it is preferable to wash with water until the electrical conductivity of the filtrate becomes 10 μS / cm or less.

[0189] (k) Step of drying the wet toner base particles In this step, the wet toner base particles that have been washed and, in some cases, further treated to remove the solvent are dried.

[0190] (l) A step of adding external additives to the dried toner base particles This step is carried out as necessary when an external additive is added to the toner base particles. The toner base particles can be used as they are as toner. Furthermore, from the viewpoints of fluidity, chargeability, cleaning properties, etc., external additives such as so-called fluidizing agents and cleaning aids may be added to the toner base particles. Examples of devices for mixing external additives include mechanical mixers such as a Henschel mixer and a coffee mill.

[0191] 5. Developer The toner can be used as a magnetic or non-magnetic one-component developer, or may be mixed with a carrier to form a two-component developer.

[0192] When the toner is used as a two-component developer, the carrier can be magnetic particles made of a conventionally known material. Examples of materials for the magnetic particles include metals (iron, ferrite, magnetite, etc.), alloys of metals with aluminum, and alloys of other metals (lead, etc.). Among these, ferrite particles are preferred.

[0193] The carrier may be a coated carrier in which the surfaces of magnetic particles are coated with a coating agent such as resin, or a dispersion type carrier in which magnetic powder is dispersed in a binder resin.

[0194] The volume-based median diameter (d50) of the carrier is preferably within a range of 20 to 100 μm, and more preferably within a range of 25 to 80 μm. The volume-based median diameter (d50) of the carrier can be measured, for example, using a laser diffraction particle size distribution analyzer "HELOS" (manufactured by SYMPATEC) equipped with a wet disperser.

[0195] The mixing device used to mix the toner and carrier is not particularly limited, and examples thereof include a Nauta mixer, a W-cone mixer, and a V-type mixer.

[0196] The toner content in the developer is preferably within a range of 4.0 to 8.0 parts by mass with respect to 100 parts by mass of the developer.

[0197] 6. Recording Media The recording medium according to this embodiment is long and has an air permeability of 20,000 sec or more at 25°C. The toner according to this embodiment is used to form an image on the recording medium. Note that "long" here specifically means 2 m or more.

[0198] The material of the recording medium is not particularly limited. Examples of the recording medium include resin film, metal film, and resin-coated paper. The resin film may be in the form of a film label having an adhesive or the like. FIG. 5 is a cross-sectional view of a film label 307 after image formation. The film label 307 has an adhesive 305 on the surface of the resin film 304 opposite to the surface having the image layer 301. The film label 307 has a release substrate 306 on the surface of the adhesive 305 opposite to the surface that contacts the resin film 304. Examples of the release substrate include release paper and release film.

[0199] In this embodiment, the term "resin film" refers to a film containing resin as a main component, specifically a film containing 60% by mass or more of resin.

[0200] Examples of the resin for the resin film include polypropylene, polyethylene, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyester, and polylactic acid. These may be contained alone or in combination of two or more. Among these, from the viewpoint of versatility, the resin is preferably polyethylene, polypropylene, or polyethylene terephthalate.

[0201] The resin film can be used for various labels, packages, etc. The resin film may be subjected to a surface treatment as appropriate for the purpose of improving printability. Examples of the surface treatment method include corona treatment and plasma treatment. The resin film may be a transparent film. The resin film may contain a pigment or the like and have any color, such as white. The resin film may have a toner-receiving layer formed on the surface.

[0202] The air permeability of a recording medium at 25°C can be measured in accordance with JIS P8117:2009 using, for example, an Oken-type air permeability tester (manufactured by Kumagaya Riki Kogyo Co., Ltd.) according to the following procedure: Start the tester and adjust the measurement reference air pressure to 49.03 hPa (500 mmH2O). Cut each of the recording media to A4 size to create three samples, and place one of these samples in the measuring section of the tester. The sample should be placed with the image-forming surface (front surface) facing upward. Then, flip the tester switch to the start position to begin measurement, and record the number of seconds measured by the tester. Measure each of the three samples, and the arithmetic average value is taken as the air permeability [sec].

[0203] The air permeability at a temperature of 25°C and a pressure of 49.03 hPa (500 mmH2O) is preferably 25,000 sec or more, which can further reduce the blocking phenomenon.

[0204] In this embodiment, the air permeability of the recording medium is measured in the state during image formation. For example, the film label 307 shown in Figure 5 has the release substrate 306 attached during image formation, and therefore the release substrate 306 is also attached when measuring the air permeability. In other words, the air permeability of the entire film label 307, including the resin film 304, adhesive 305, and release substrate 306, is 20,000 sec or more at 25°C.

[0205] The thickness of the recording medium is preferably in the range of 20 to 1000 μm, more preferably in the range of 40 to 500 μm. When the recording medium includes a release substrate, it is preferable that the thickness of the release substrate also falls within the above range.

[0206] 7.Image forming method In the image forming method of this embodiment, the toner is used in the form of the developer to form an image on the recording medium.

[0207] The image forming method of the present embodiment is an image forming method for forming an image on a recording medium using a toner for developing an electrostatic image, the toner including toner base particles containing a binder resin, The binder resin contains a styrene-(meth)acrylic resin and a polyester, the mass ratio of the styrene-(meth)acrylic resin to the polyester is within the range of 80:20 to 1:99; The recording medium is long, The air permeability of the recording medium is 20,000 sec or more.

[0208] An example of an image forming method using a two-component developer will be described below, but the image forming method of this embodiment is not limited to this as long as the above-described developer and recording medium are used.

[0209] The image forming method of this embodiment can be carried out using an electrophotographic image forming apparatus. Figure 7 is a cross-sectional schematic diagram of an electrophotographic image forming apparatus.

[0210] The electrophotographic image forming method preferably includes the following steps. 1) Charging process to charge the surface of the image carrier (photoconductor) 2) An electrostatic image forming process in which an electrostatic image is formed on the surface of a charged image carrier. 3) A developing step in which the electrostatic image formed on the surface of the image carrier is developed into a toner image using a developer. 4) A transfer step in which the toner image formed on the surface of the image carrier is transferred to the surface of a recording medium. 5) A fixing process in which the toner image transferred onto the surface of the recording medium is fixed. 6) A cleaning step for cleaning the surface of the image carrier

[0211] The configuration of the image forming apparatus will be described. The image forming apparatus 100 is a so-called tandem color image forming apparatus, and includes an original image reading device SC, four image forming units, a transfer device, a conveying device, and a fixing device 50.

[0212] The four image forming units are devices for forming images of four colors: yellow (Y), magenta (M), cyan (C), and black (K). For example, the four image forming units are arranged in the order of YMCK from top to bottom in FIG. 7. Each image forming unit has a photoreceptor 1, a charging device 2, an exposure device 3, a developing device 4, a primary transfer roller 5, and a cleaning device 6.

[0213] The photoreceptor 1 is, for example, a drum-shaped organic photoreceptor, and the charging device 2 is, for example, a non-contact charging device that uses corona discharge. The exposure device 3 is, for example, a laser oscillation device, and the developing device 4 is a developing device for a two-component developer that contains a two-component developer of one of the colors YMCK. The primary transfer roller 5 is, for example, a charging roller that is freely urged toward the photoreceptor 1 via an intermediate transfer belt 7. The cleaning device 6 is, for example, a blade cleaning device that has an elastic blade made of rubber that contacts the surface of the photoreceptor 1.

[0214] The transfer device has an endless intermediate transfer belt 7, multiple rollers 8 that tension the intermediate transfer belt 7, a secondary transfer roller 9, and a cleaning device 10. The rollers 8 include one or more drive rollers and may further include a driven roller other than the drive roller. The secondary transfer roller 9 is, for example, a charging roller that forms a nip between the intermediate transfer belt 7 and the recording medium RM being conveyed therethrough. The cleaning device 10 is, for example, a blade cleaning device that has an elastic blade that contacts the surface of the intermediate transfer belt 7.

[0215] The transport device includes a drawer 61 , transport rollers 13 and 15 , a resist roller 14 , and a winding unit 65 .

[0216] The drawer 61 has a storage section 62 that stores a roll of recording medium RM, and a transport unit 63 for transporting successive sheets of the recording medium RM to the upstream portion of the transport device. The storage section 62 has a transport roller 64 for transporting the drawn-out recording medium RM. The winder 65 has a transport unit 66 that feeds back the recording medium RM on which a toner image has been formed, and a storage section 67 for storing the recording medium RM transported from the transport unit 66 in roll form.

[0217] The procedure for forming an image will be described. The document image reading device SC reads the image information of the document, converts it into image data for each color of YMCK, and sends the image data for the corresponding color to the exposure device 3, which will be described later. In the image forming section, the surface of the rotationally driven photoconductor 1 is charged by the application of a voltage from the charging device 2. The exposure device 3 irradiates the charged surface of the photoconductor 1 with laser light corresponding to the image data for the corresponding color of YMCK, forming an electrostatic image. Toner is supplied from the developing device 4 to the surface of the photoconductor 1 on which the electrostatic image has been formed, and the toner adheres to the electrostatic image, developing the electrostatic image.

[0218] The toner images of each color of YMCK carried on the surface of the photoreceptor 1 formed in the image forming unit are transferred onto the rotating intermediate transfer belt 7 so as to be successively superimposed upon each other by application of voltage from the primary transfer roller 5. In this way, a composite color toner image is formed on the intermediate transfer belt 7. The primary transfer roller 5 may be in contact with the photoreceptor 1 only during the primary transfer. For example, the primary transfer roller 5 in the image forming unit for black images is in constant contact with the photoreceptor 1, and the primary transfer rollers 5 for the other colors are in contact with the photoreceptor 1 only during the primary transfer.

[0219] After the primary transfer, the cleaning device 6 removes any adhering matter such as transfer residual toner from the surface of the photoreceptor 1 .

[0220] The recording medium RM stored in the storage section 62 is drawn out by a transport roller 64 and transported to a transport unit 63. The recording medium RM is then transported to a secondary transfer roller 9 via a transport roller 13 and a registration roller 14. The transport roller 13 transports the recording medium RM to the nip portion of the secondary transfer roller 9, and the registration roller 14 controls the position of the transported recording medium RM. The color toner image on the intermediate transfer belt 7 is transferred onto the recording medium RM by application of a voltage from the secondary transfer roller 9. The secondary transfer roller 9 is, for example, biased toward the intermediate transfer belt 7 only during secondary transfer.

[0221] After the secondary transfer, the cleaning device 10 removes any adhering matter such as transfer residual toner from the surface of the intermediate transfer belt 7 .

[0222] The color toner image on the recording medium RM is fixed to the surface of the recording medium RM by the application of heat and pressure by the fixing device 50, and a color toner image is formed on the recording medium RM. The recording medium RM on which the color toner image has been formed is transported to the winding section 65 via the transport roller 15. By repeating the above process, toner images are formed one after another on the recording medium RM.

[0223] 8. Image formation The image-formed product of the present embodiment has an image layer on the recording medium, and the image layer contains the toner. The recording medium and the toner are as described above.

[0224] In the image-formed product of this embodiment, the image layer has at least one void in a region of 200 μm width in the cross section in the thickness direction.

[0225] 8 is a schematic cross-sectional view in the thickness direction of the image-formed product 308. In this embodiment, the term "void" refers to a space where no toner is present in the image layer 301 on the recording medium 303. For example, when the cross section of the image-formed product 308 is observed with a scanning electron microscope (SEM), the void 309 appears darker than the surrounding areas where toner is present.

[0226] In this embodiment, the image layer has at least one void within a width of 200 μm. That is, the distance between multiple voids in the image layer is less than 200 μm. This allows the image layer to have an appropriate number of voids, allowing charges to escape through the voids. The voids preferably face the surface of the image layer or the interface between the image layer and the recording medium. Having the voids facing the surface of the image layer increases the surface area of ​​the image layer, making it easier for charges in the image layer to escape outside the image-formed product. Furthermore, having the voids facing the interface between the image layer and the recording medium makes it easier for charges in the image layer to escape outside the image-formed product via the recording medium. [Example]

[0227] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass." In the following examples, unless otherwise specified, the experiments were carried out at room temperature (25°C).

[0228] 1. Toner production (1) Preparation of styrene-(meth)acrylic resin particle dispersion (1.1) Preparation of styrene-(meth)acrylic resin particle dispersion (S1) (First stage polymerization) The following components were placed in a 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet. The internal temperature of the reaction vessel was raised to 81°C while stirring the contents in the reaction vessel at a stirring speed of 230 rpm under a nitrogen stream. Sodium dodecyl sulfate 8.0 parts by mass Ion-exchanged water 3000.0 parts by mass

[0229] After the temperature was raised, a solution obtained by dissolving the following components in the reaction vessel was added. Potassium persulfate 10.0 parts by mass Ion-exchanged water 200.0 parts by mass

[0230] The liquid temperature in the reaction vessel was again raised to 81°C, and the following mixed liquid of monomers was added dropwise over 1 hour. After the dropwise addition, the mixture was maintained at the same temperature for 2 hours to prepare a styrene-(meth)acrylic resin particle dispersion (S1-a). Styrene 470.0 parts by mass n-Butyl acrylate (n-butyl acrylate) 250.0 parts by mass Methacrylic acid 78.0 parts by mass

[0231] (Second stage polymerization) The following components were placed in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen inlet, and heated to 87°C. Ion-exchanged water 970.0 parts by mass Styrene-(meth)acrylic resin particle dispersion (S1-a) prepared by the first-stage polymerization (solid content equivalent) 34.0 parts by mass

[0232] Next, separately from the mixture in the reaction vessel, the following monomers, chain transfer agent and release agent were dissolved at 80° C. to obtain a mixed liquid. Styrene 200.0 parts by mass 2-Ethylhexyl acrylate 108.0 parts by mass Methacrylic acid 75.0 parts by mass n-Octyl-3-mercaptopropionate (chain transfer agent) 3.0 parts by mass Behenyl behenate (mold release agent, melting point 73°C) 181.8 parts by mass

[0233] The resulting mixture was mixed and dispersed for 15 minutes using a mechanical disperser with a circulation path, "Clearmix" (manufactured by M Technique Co., Ltd.), to prepare a dispersion containing emulsified particles (oil droplets). The resulting dispersion was added to the 5 L reaction vessel.

[0234] A solution obtained by dissolving the following components was added to a reaction vessel, and then the system was heated and stirred at 87°C for 1 hour to carry out polymerization, thereby preparing a styrene-(meth)acrylic resin particle dispersion (S1-b). Potassium persulfate 4.5 parts by mass Ion-exchanged water 90.0 parts by mass

[0235] (Third stage polymerization) A solution obtained by dissolving the following components was added to the styrene-(meth)acrylic resin particle dispersion (S1-b) obtained by the second-stage polymerization. Potassium persulfate 6.0 parts by mass Ion-exchanged water 115.0 parts by mass

[0236] A mixed solution of the following monomers and chain transfer agent was added dropwise to the reaction vessel over 80 minutes at a temperature of 84°C. Styrene 280.0 parts by mass n-Butyl acrylate (n-butyl acrylate) 150.0 parts by mass Methacrylic acid (MAA) 66.0 parts by mass Methyl methacrylate (MMA) 86.0 parts by mass n-Octyl-3-mercaptopropionate 7.0 parts by mass

[0237] After the dropwise addition was completed, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to prepare a styrene-(meth)acrylic resin particle dispersion (S1) with a solids content of 25% by mass. The median diameter of the vinyl resin particles was 120 nm, and the weight-average molecular weight Mw was 31,000. In the following, to distinguish between the dispersions obtained in the first, second, and third polymerization stages, the dispersion obtained in the third polymerization stage will also be referred to as a styrene-(meth)acrylic resin particle dispersion (S1-c).

[0238] (1.2) Preparation of styrene-(meth)acrylic resin particle dispersions (S2) to (S7) and (S10) to (S12) Dispersions (S2) to (S7) and (S10) to (S12) were prepared in the same manner as in the preparation of dispersion (S1), except that in the second-stage polymerization for preparing dispersion (S1-b), the amount of release agent added was changed to the amount shown in Table I.

[0239] (1.3) Preparation of styrene-(meth)acrylic resin particle dispersions (S8) and (S9) Dispersions (S8) and (S9) were prepared in the same manner as in the preparation of Dispersion (S1), except that in the second-stage polymerization to prepare Dispersion (S1-b) and the third-stage polymerization to prepare Dispersion (S1-c), the amounts of release agent added, the amounts of monomer added, and the types of monomers were changed to the amounts shown in Tables I and II. In Dispersion (S9), stearyl methacrylate was used instead of methyl methacrylate (MMA) as the monomer in the third-stage polymerization.

[0240] Tables I and II show the monomer compositions of the resins contained in the styrene-(meth)acrylic resin particle dispersions (S1) to (S12). The "mold release agent" in Table I is specifically behenyl behenate.

[0241] [Table 1]

[0242] [Table 2]

[0243] (2) Preparation of crystalline polyester particle dispersion (2.1) Preparation of crystalline polyester particle dispersion (PC1) (2.1.1) Synthesis of crystalline polyester (pC1) The following monomers were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 190° C. to dissolve them. Carboxylic Acid Tetradecanedioic acid 450.0 parts by mass ·alcohol 1,6-Hexanediol 266.0 parts by mass

[0244] Next, the following components were added as an esterification catalyst to the four-neck flask, and the temperature was raised to 240° C. Thereafter, the reaction was carried out under normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour. Tetra-normal-butyl titanate (tetrabutyl orthotitanate; Ti(On-Bu)4) 0.8 parts by mass

[0245] The contents of the four-neck flask were then cooled to 200°C, and the mixture was reacted under reduced pressure (20 kPa) for 1 hour to obtain a crystalline polyester (pC1). The resulting crystalline polyester (pC1) had a weight average molecular weight (Mw) of 20,700 and a melting point (mp) of 74°C.

[0246] (2.1.2) Preparation of crystalline polyester particle dispersion (PC1) The following ingredients were dissolved: 100.0 parts by mass of the crystalline polyester (pC1) obtained above Ethyl acetate (Kanto Chemical Co., Ltd.) 400.0 parts by mass

[0247] The resulting solution was mixed with the following solution that had been prepared in advance. 638.0 parts by mass of 0.26% by mass sodium lauryl sulfate solution

[0248] The resulting mixture was subjected to ultrasonic dispersion treatment at V-LEVEL 300 μA for 30 minutes using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while stirring.

[0249] The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump "V-700" (manufactured by BUCHI Corporation) to completely remove the ethyl acetate, thereby preparing a crystalline polyester particle dispersion (CP1). The crystalline polyester particles in the dispersion had a volume-based median diameter of 150 nm.

[0250] (2.2) Preparation of crystalline polyester particle dispersion (PC2) In the synthesis of crystalline polyester (pC2), the carboxylic acid and alcohol were changed to the following components. Other than this, the crystalline polyester particle dispersion (PC1) was prepared in the same manner. Carboxylic Acid Tetradecanedioic acid 250.0 parts by mass Stearic acid 200.0 parts by mass ·alcohol 1,6-Hexanediol 266.0 parts by mass

[0251] (2.3) Preparation of crystalline polyester particle dispersion (PC3) In the synthesis of crystalline polyester (pC3), the carboxylic acid and alcohol were changed to the following components. Other than this, the same procedure as for the crystalline polyester particle dispersion (PC1) was used to prepare the crystalline polyester (pC3). Carboxylic Acid Tetradecanedioic acid 442.0 parts by mass ·alcohol 1,4-butanediol 287.0 parts by mass

[0252] (2.4) Preparation of crystalline polyester particle dispersion (PC4) (2.4.1) Synthesis of crystalline polyester (pC4-a) The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and the following components were added to the flask. The hydrocarbon wax functioned as a dispersant. Bisphenol A propylene oxide 2.2 mole adduct 3253.0 parts by mass Terephthalic acid 1003.0 parts by mass Tin(II) di(2-ethylhexanoate) 25.0 parts by mass 3,4,5-trihydroxybenzoic acid 2.5 parts by mass Hydrocarbon wax "Paracol 6490" (manufactured by Nippon Seiro Co., Ltd., acid value 18 mg KOH / g, hydroxyl value 97 mg KOH / g) 394.0 parts by mass

[0253] Under a nitrogen atmosphere, the mixture was heated to 235°C while stirring and maintained at 235°C for 8 hours, after which the pressure inside the flask was reduced and maintained at 8 kPa for 1 hour. Thereafter, the flask was cooled to 160°C and returned to atmospheric pressure. With the temperature maintained at 160°C, a mixture of the following components was added dropwise over 3 hours.

[0254] Styrene 2139.0 parts by mass Stearyl methacrylate 535.0 parts by mass Acrylic acid 107.0 parts by mass Dibutyl peroxide 321.0 parts by mass

[0255] The temperature inside the flask was then maintained at 160°C for 30 minutes, then increased to 200°C, and the pressure inside the flask was further reduced and maintained at 8 kPa for 1 hour.The pressure inside the flask was then returned to atmospheric pressure, and the temperature inside the flask was cooled to 190°C, and the following components were added. Fumaric acid 129.0 parts by mass Sebacic acid 94.0 parts by mass Trimellitic anhydride 214.0 parts by mass 4-tert-butylcatechol 2.5 parts by mass

[0256] The temperature inside the flask was raised to 210°C at a rate of 10°C / hr, and then the reaction was carried out at 4 kPa until the desired softening point was reached, thereby obtaining a crystalline polyester (pC4-a).

[0257] (2.4.2) Synthesis of crystalline polyester (pC4-b) The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and the following components were added. 1,10-Decanediol 3416.0 parts by mass Sebacic acid 4084.0 parts by mass

[0258] While stirring the mixture, the temperature inside the flask was raised to 135°C and maintained at 135°C for 3 hours, and then the temperature was raised from 135°C to 200°C over 10 hours. After that, the following components were added, and the mixture was maintained at 200°C for another hour, after which the pressure inside the flask was reduced and the mixture was maintained under a reduced pressure of 8.3 kPa for 1 hour to obtain a crystalline polyester (pC4-b). Tin(II) di(2-ethylhexanoate) 23.0 parts by mass

[0259] (2.4.3) Preparation of crystalline polyester particle dispersion (PC4) The following components were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen inlet tube, and the resin was dissolved at 73° C. for 2 hours. Crystalline polyester (pC4-a) 210.0 parts by mass Crystalline polyester (pC4-b) 90.0 parts by mass Methyl ethyl ketone 300.0 parts by mass Deionized water 49.0 parts by mass

[0260] To the resulting solution, a 5% by mass aqueous solution of sodium hydroxide was added so as to achieve a degree of neutralization of 50 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes.

[0261] Next, while maintaining the temperature inside the vessel at 73°C, 600 g of deionized water was added over 60 minutes while stirring at 280 r / min (circumferential speed 88 m / min) to cause phase inversion emulsification. While continuing to maintain the temperature inside the vessel at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, the aqueous dispersion was cooled to 30°C while stirring at 280 r / min (circumferential speed 63 m / min), and deionized water was added to obtain a solids concentration of 20% by mass, thereby obtaining a crystalline polyester particle dispersion (PC4).

[0262] Table III shows the compositions of crystalline polyester particle dispersions (PC1) to (PC4). As shown in Table III, dispersions (PC1) to (PC3) each contain one type of unmodified polyester. Dispersion (PC4) contains two types of resins: a polyester modified with a styrene-(meth)acrylic resin and an unmodified polyester. Here, "unmodified" means that the crystalline polyester has not been modified with any compound other than the monomer that forms the repeating unit.

[0263] [Table 3]

[0264] (3) Preparation of amorphous polyester particle dispersion (3.1) Preparation of amorphous polyester particle dispersion (P1) (3.1.1) Synthesis of amorphous polyester (p1) The following monomers for the amorphous polyester resin were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them. Bisphenol A ethylene oxide 2 mole adduct 50.2 parts by mass Bisphenol A propylene oxide 2 mole adduct 249.8 parts by mass Terephthalic acid 120.1 parts by mass Dodecenyl succinic acid 46.0 parts by mass

[0265] With stirring, the mixed liquid placed in the dropping funnel was added dropwise to the four-necked flask over 90 minutes, and after aging for 60 minutes, the unreacted monomer was removed under reduced pressure (8 kPa).

[0266] Thereafter, the following components were added to the flask as an esterification catalyst, and the temperature was raised to 235°C, and the reaction was carried out under normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour. Tetra-normal-butyl titanate (tetrabutyl orthotitanate; Ti(On-Bu)4) 0.4 parts by mass

[0267] The flask was then cooled to 200°C, and the reaction was carried out under reduced pressure (20 kPa), after which the solvent was removed to obtain amorphous polyester (p1). The obtained amorphous polyester (p1) had a weight average molecular weight (Mw) of 22,000.

[0268] (3.1.2) Preparation of amorphous polyester particle dispersion (P1) The following ingredients were dissolved: 100.0 parts by mass of the amorphous polyester (p1) obtained above Ethyl acetate (Kanto Chemical Co., Ltd.) 400.0 parts by mass

[0269] The resulting solution was mixed with the following solution that had been prepared in advance. 638.0 parts by mass of 0.26% by mass sodium lauryl sulfate solution

[0270] The resulting mixture was subjected to ultrasonic dispersion treatment at V-LEVEL 300 μA for 30 minutes using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while stirring.

[0271] The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump "V-700" (manufactured by BUCHI Corporation) to completely remove the ethyl acetate, thereby preparing an amorphous polyester particle dispersion (P1) with a solids concentration of 13.5% by mass. The crystalline polyester particles in the dispersion had a volume-based median diameter of 120 nm.

[0272] (3.2) Preparation of amorphous polyester particle dispersion (P2) (3.2.1) Synthesis of amorphous polyester (p2) The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and the following components were placed in the four-neck flask. Bisphenol A propylene oxide 2.2 mole adduct 5001.0 parts by mass Terephthalic acid 1788.0 parts by mass Tin(II) di(2-ethylhexanoate) 30.0 parts by mass 3,4,5-trihydroxybenzoic acid 3.0 parts by mass

[0273] Under a nitrogen atmosphere, the mixture was heated to 235°C while stirring and maintained at 235°C for 8 hours, after which the pressure inside the flask was reduced and maintained at -8 kPa(G) for 1 hour. After that, the pressure inside the flask was returned to atmospheric pressure, the temperature inside the flask was cooled to 180°C, and the following components were added. Fumaric acid 179.0 parts by mass Dodecenyl succinic anhydride 206.0 parts by mass Trimellitic anhydride 325.0 parts by mass 4-tert-butylcatechol 3.8 parts by mass

[0274] The temperature inside the flask was raised to 220° C. at a rate of 10° C. / hr, and then the pressure inside the flask was reduced and the reaction was carried out at −10 kPa (G) until the desired softening point was reached, thereby obtaining amorphous polyester (p2).

[0275] (3.2.2) Preparation of amorphous polyester particle dispersion (P2) The following components were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen inlet tube, and the resin was dissolved at 73° C. for 2 hours. 300.0 parts by mass of the amorphous polyester (p2) obtained above Methyl ethyl ketone 300.0 parts by mass Deionized water 41.0 parts by mass

[0276] To the resulting solution, a 5% by mass aqueous solution of sodium hydroxide was added so as to achieve a degree of neutralization of 60 mol% relative to the acid value of the amorphous polyester (p2), and the mixture was stirred for 30 minutes.

[0277] Next, while maintaining the temperature inside the vessel at 73°C, 600 g of deionized water was added over 60 minutes while stirring at 200 r / min (circumferential speed 63 m / min) to cause phase inversion emulsification. While continuing to maintain the temperature inside the vessel at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, the aqueous dispersion was cooled to 30°C while stirring at 280 r / min (circumferential speed 88 m / min), and deionized water was added to obtain a solids concentration of 20% by mass, thereby obtaining amorphous polyester particle dispersion (P2).

[0278] (4) Preparation of release agent particle dispersion (4.1) Preparation of release agent particle dispersion (W1) (4.1.1) Synthesis of resin (y1) The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and the following components were added. Bisphenol A propylene oxide 2.2 mole adduct 4313.0 parts by mass Terephthalic acid 818.0 parts by mass Succinic acid 727.0 parts by mass Tin(II) di(2-ethylhexanoate) 30.0 parts by mass 3,4,5-trihydroxybenzoic acid 3.0 parts by mass

[0279] Under a nitrogen atmosphere, the temperature inside the flask was raised to 235°C while stirring the mixture, and after maintaining this temperature for 5 hours, the pressure inside the flask was reduced and maintained at 8 kPa for 1 hour. After that, the pressure inside the flask was returned to atmospheric pressure, and the temperature inside the flask was cooled to 160°C. While maintaining this temperature at 160°C, a mixture of the following components was added dropwise over 1 hour. Styrene 2756.0 parts by mass Stearyl methacrylate 689.0 parts by mass Acrylic acid 142.0 parts by mass Dibutyl peroxide 413.0 parts by mass

[0280] Thereafter, the temperature inside the flask was maintained at 160° C. for 30 minutes, and then the temperature was increased to 200° C. Next, the pressure inside the flask was further reduced, and the reaction was carried out at 8 kPa until the desired softening point was reached, thereby obtaining resin (y1), which was an amorphous polyester.

[0281] (4.1.2) Preparation of resin particle dispersion (Y1) The following components were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen inlet tube, and the resin was dissolved at 73° C. for 2 hours. Resin (y1) 200.0 parts by mass Methyl ethyl ketone 200.0 parts by mass

[0282] To the resulting solution, a 5% by mass aqueous solution of sodium hydroxide was added so as to achieve a degree of neutralization of 60 mol% relative to the acid value of the resin (y1), and the mixture was stirred for 30 minutes.

[0283] Next, while maintaining the temperature inside the vessel at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 280 r / min (circumferential speed 88 m / min) to cause phase inversion emulsification. While continuing to maintain the temperature inside the vessel at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, while continuing to stir at 280 r / min (circumferential speed 88 m / min), the aqueous dispersion was cooled to 30°C, and deionized water was added to obtain a solids concentration of 20% by mass, thereby obtaining resin particle dispersion (Y1).

[0284] (4.1.3) Preparation of release agent particle dispersion (W1) The following components were added to a 1 L beaker. The temperature inside the beaker was maintained at a range of 90 to 95°C to melt the following components and stir to obtain a molten mixture. Deionized water 545.4 parts by mass Resin particle dispersion (Y1) 390.9 parts by mass Paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C) 181.8 parts by mass

[0285] The obtained molten mixture was further dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while being maintained at a temperature within the range of 90 to 95°C. The molten mixture was then cooled to room temperature (25°C). Deionized water was added to adjust the solid content to 20% by mass, thereby obtaining a release agent particle dispersion (W1). The volume median particle diameter D50 of the release agent particles in the dispersion was 0.47 μm, and the CV value was 27%.

[0286] (4.2) Preparation of release agent particle dispersion (W2) The following components were added to a 1 L beaker. The temperature inside the beaker was maintained at a range of 90 to 95°C to melt the following components and stir to obtain a molten mixture. Deionized water 545.4 parts by mass Resin particle dispersion (Y1) 390.9 parts by mass Behenyl behenate 181.8 parts by mass

[0287] The obtained molten mixture was further dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while being maintained at a temperature within the range of 90 to 95°C. The molten mixture was then cooled to room temperature (25°C). Deionized water was added to adjust the solid content to 20% by mass, thereby obtaining a release agent particle dispersion (W2). The volume median particle diameter D50 of the release agent particles in the dispersion was 0.43 μm, and the CV value was 25%.

[0288] (5) Preparation of colorant particle dispersion (Cy1) The following components were mixed and dispersed using a high-pressure impact disperser Ultimizer HJP30006 (manufactured by Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion (Cy1). The median particle diameter of the obtained colorant was 150 nm. Cyan pigment (Dainichiseika Color & Chemicals Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine) 420.0 parts by mass Anionic surfactant "Neogen (registered trademark) R" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 80.0 parts by mass Ion-exchanged water 1600.0 parts by mass

[0289] (6) Preparation of toner base particles (6.1) Preparation of toner base particles (1) The following components were placed in a reaction vessel equipped with a stirrer, a temperature sensor, and a condenser. Styrene-(meth)acrylic resin particle dispersion (S1) (Solid content equivalent: resin) 1763.0 parts by mass (Solid content equivalent: release agent) 181.8 parts by mass Ion-exchanged water 2000.0 parts by mass

[0290] At room temperature (25°C), a 5 mol / L aqueous solution of sodium hydroxide was added to the container to adjust the pH inside the container to 10. Next, the following components were placed in the container. Colorant particle dispersion (Cy1) (solid content equivalent) 210.0 parts by mass

[0291] Next, the temperature inside the vessel was raised to 30°C, and a solution obtained by dissolving the following components was added over 10 minutes while stirring inside the vessel. Magnesium chloride 60.0 parts by mass Ion-exchanged water 60.0 parts by mass

[0292] The reaction mixture in the vessel was left for 3 minutes and then heated to 80°C over 60 minutes. The agitator was then set to 300 rpm and stirred for 30 minutes. The agitation speed was then adjusted to a particle size growth rate of 0.01 μm / min, and particles were grown until the volumetric median diameter measured using a Coulter Multisizer 4e (Beckman Coulter, Inc.) reached the target particle size of 6.0 μm. While particle size growth was performed at 80°C, it was confirmed that particle size growth could be achieved at temperatures other than 80°C, as long as the temperature was 30–40°C higher than the designed glass transition temperature (Tg) of the styrene-(meth)acrylic resin.

[0293] The following ingredients were then added to the container over a 30 minute period: Amorphous polyester particle dispersion (P1) (solid content equivalent) 440.8 parts by mass

[0294] When the supernatant of the reaction solution became transparent, a solution obtained by dissolving the following components was added to stop the growth of particle size. Sodium chloride 250.0 parts by mass Ion-exchanged water 860.0 parts by mass

[0295] Next, the reaction liquid was stirred at 80°C with the stirrer set at 300 rpm, and the fusion of the particles was allowed to proceed until the average circularity of the toner base particles reached 0.970. Thereafter, the reaction liquid was cooled to a temperature of 30°C or below.

[0296] Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and washed by repeating the solid-liquid separation process three times. After washing, the toner base particles (1) were obtained by drying at 40°C for 24 hours.

[0297] (6.2) Preparation of toner base particles (2) The following components were placed in a reaction vessel equipped with a stirrer, a temperature sensor, and a condenser. Styrene-(meth)acrylic resin particle dispersion (S1) (Solid content equivalent: resin) 1322.4 parts by mass (Solid content equivalent: release agent) 181.8 parts by mass Ion-exchanged water 2000.0 parts by mass

[0298] At room temperature (25°C), a 5 mol / L aqueous solution of sodium hydroxide was added to the container to adjust the pH to 10. Next, the following components were placed in the container. Colorant particle dispersion (Cy1) (solid content equivalent) 210.0 parts by mass

[0299] Next, the temperature inside the vessel was raised to 30°C, and a solution obtained by dissolving the following components was added over 10 minutes while stirring inside the vessel. Magnesium chloride 60.0 parts by mass Ion-exchanged water 60.0 parts by mass

[0300] The reaction solution in the vessel was left for 3 minutes, and then heated to 80°C over 60 minutes. After the temperature reached 80°C, the following components were added to the vessel over 20 minutes. During addition, the stirrer was set to 300 rpm. Crystalline polyester particle dispersion (PC1) (solid content equivalent) 440.8 parts by mass

[0301] The stirring speed was then adjusted so that the particle size growth rate was 0.01 μm / min, and the particles were allowed to grow until the volume-based median diameter measured using a Coulter Multisizer 4e (manufactured by Beckman Coulter, Inc.) reached the target particle size of 6.0 μm.

[0302] The following ingredients were then added to the container over a 30 minute period: Amorphous polyester particle dispersion (P1) (solid content equivalent) 440.8 parts by mass

[0303] When the supernatant of the reaction solution became transparent, a solution obtained by dissolving the following components was added to stop the growth of particle size. Sodium chloride 250.0 parts by mass Ion-exchanged water 860.0 parts by mass

[0304] Next, the reaction liquid was stirred at 80°C with the stirrer set at 300 rpm, and the fusion of the particles was allowed to proceed until the average circularity of the toner base particles reached 0.970. Thereafter, the reaction liquid was cooled to a temperature of 30°C or below.

[0305] Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and washed by repeating the solid-liquid separation operation three times. After washing, the toner base particles (2) were obtained by drying at 40°C for 24 hours.

[0306] (6.3) Preparation of toner base particles (3), (4), (6) to (9), (11), (12) and (15) The types and contents of the various resin particle dispersions were changed as shown in Table 4. Other than this, each toner base particle was produced using the same procedure as in the production of toner base particles (2).

[0307] (6.4) Preparation of toner base particles (5) The following components were placed in a reaction vessel equipped with a stirrer, a temperature sensor, and a condenser. Styrene-(meth)acrylic resin particle dispersion (S5) (Solid content equivalent: resin) 110.2 parts by mass Ion-exchanged water 2000.0 parts by mass

[0308] At room temperature (25°C), a 5 mol / L aqueous solution of sodium hydroxide was added to the container to adjust the pH to 10. Next, the following components were placed in the container. Colorant particle dispersion (Cy1) (solid content equivalent) 210.0 parts by mass Release agent particle dispersion (W2) (solid content equivalent) 181.8 parts by mass The mass of the release agent particle dispersion (W2) calculated as solid content includes only the mass of the release agent and does not include the mass of the resin (y1).

[0309] Next, the temperature inside the vessel was raised to 30°C, and a solution obtained by dissolving the following components was added over 10 minutes while stirring inside the vessel. Magnesium chloride 60.0 parts by mass Ion-exchanged water 60.0 parts by mass

[0310] The reaction solution in the container was left to stand for 5 minutes, and then the following components were added to the container over a period of 50 minutes. Crystalline polyester particle dispersion (PC1) (solid content equivalent) 1653.0 parts by mass

[0311] After the addition was complete, the reaction solution in the vessel was heated to 80°C over 60 minutes. After reaching 80°C, the agitator was set to 300 rpm and the mixture was stirred for 30 minutes. The agitation speed was then adjusted to a particle size growth rate of 0.01 μm / min, and the particles were allowed to grow until the volume-based median diameter, measured using a Coulter Multisizer 4e (Beckman Coulter, Inc.), reached the target particle size of 6.0 μm.

[0312] The following ingredients were then added to the container over a 30 minute period: Amorphous polyester particle dispersion (P1) (solid content equivalent) 440.8 parts by mass

[0313] When the supernatant of the reaction solution became transparent, a solution obtained by dissolving the following components was added to stop the growth of particle size. Sodium chloride 250.0 parts by mass Ion-exchanged water 860.0 parts by mass

[0314] Next, the reaction liquid was heated to 80°C and stirred to allow the particles to fuse together until the average circularity of the toner base particles reached 0.970, after which the reaction liquid was cooled to a temperature of 30°C or lower.

[0315] Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and washed by repeating the solid-liquid separation process three times. After washing, the toner base particles (5) were obtained by drying at 40°C for 24 hours.

[0316] (6.5) Preparation of toner base particles (10) and (14) The types and contents of the various resin particle dispersions were changed as shown in Table 4. Other than this, toner base particles (10) and (14) were prepared using the same procedure as for preparing toner base particles (1).

[0317] (6.6) Preparation of toner base particles (13) The following components were placed in a reaction vessel equipped with a stirrer, a temperature sensor, and a condenser, and mixed at room temperature (25°C). Crystalline polyester particle dispersion (PC4) (solid content equivalent) 1961.4 parts by mass Release agent particle dispersion (W1) (solid content equivalent) 181.8 parts by mass Colorant particle dispersion (Cy1) (solid content equivalent) 210.0 parts by mass 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neopelex G-15" (Kao Corporation, anionic surfactant) 20.0 parts by mass The mass of the release agent particle dispersion (W1) calculated as solid content includes only the mass of the release agent, and does not include the mass of the resin (y1).

[0318] A 4.8% by mass aqueous solution of potassium hydroxide was added to an aqueous solution prepared by dissolving 80 parts by mass of ammonium sulfate in 1,236 parts by mass of deionized water to prepare a solution with a pH of 8.6. While stirring the mixture in the reaction vessel, this solution was added dropwise over 10 minutes at 25°C. The reaction vessel was then heated to 59°C over 2 hours and maintained at 59°C until the volume median particle diameter D50 of the aggregated particles reached 5.5 μm, yielding a dispersion of aggregated particles (1).

[0319] While the temperature of the dispersion of aggregated particles (1) was maintained at 59° C., the following components were added dropwise at a rate of 0.7 mL / min to obtain a dispersion of aggregated particles (2). Amorphous polyester particle dispersion (P2) (solid content equivalent) 242.4 parts by mass

[0320] To the resulting dispersion of aggregated particles (2), a solution obtained by mixing the following components was added. Sodium polyoxyethylene lauryl ether sulfate "EMAL E-27C" (Kao Corporation, anionic surfactant, effective concentration 27% by mass) 36.0 parts by mass Deionized water 313.0 parts by mass 0.1 mol / L sulfuric acid aqueous solution 40.0 parts by mass

[0321] The dispersion of aggregated particles (2) was heated to 80°C over 1 hour and held at 80°C for 30 minutes, after which the following components were added and the mixture was further held at 80°C for 15 minutes. 20.0 parts by mass of 0.1 mol / L sulfuric acid aqueous solution Thereafter, the following components were added to the dispersion of aggregated particles (2), and the mixture was kept at 80° C. until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which the aggregated particles were fused together. 20.0 parts by mass of 0.1 mol / L sulfuric acid aqueous solution

[0322] Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and washed by repeating the solid-liquid separation process three times. After washing, the toner was dried at 40°C for 24 hours to obtain toner base particles (13).

[0323] (mass ratio of styrene-(meth)acrylic resin to polyester) The crystalline polyester (pC4) was composed of crystalline polyesters (pC4-a) and (pC4-b). The crystalline polyester (pC4-a) was a crystalline polyester modified with styrene-(meth)acrylic resin, and was composed of a styrene-(meth)acrylic resin component and a polyester component. In the crystalline polyester (pC4-a), the mass ratio of the styrene-(meth)acrylic resin to the polyester was 35:65.

[0324] In the crystalline polyester (pC4), the mass ratio of the crystalline polyesters (pC4-a) and (pC4-b) was 210:90. Therefore, in the crystalline polyester (pC4), the mass ratio of the styrene-(meth)acrylic resin to the polyester was 210×0.35:210×0.65+90=24.5:75.5.

[0325] In the toner base particles (13), the mass ratio of the crystalline polyester (pC4) to the amorphous polyester (p2) is 89: 11. Therefore, the mass ratio of the styrene-(meth)acrylic resin to the polyester is 89 x 0.245: 89 x 0.755 + 11 = 21.8: 78.2.

[0326] Tables IV and V show the compositions of toner base particles (1) to (14). Table IV shows the content of each constituent material (solid content equivalent) in parts by mass, and Table V shows the content of each constituent component in % by mass.

[0327] [Table 4]

[0328] [Table 5]

[0329] (7) Toner production The following external additives were added to the obtained toner base particles (1) to (15). These mixtures were mixed in a Henschel mixer (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm / sec and 32°C for 20 minutes. After mixing, coarse particles were removed using a sieve with 45 μm openings, and toners (1) to (15) were obtained. The volume-based median diameter of the toner was 6.1 μm. Toner base particles 100.0 parts by mass Hydrophobic silica particles (number average primary particle size: 12 nm, hydrophobicity: 68) 0.6 parts by mass Hydrophobic titanium oxide particles (number average primary particle size: 20 nm, hydrophobicity: 63) 1.0 parts by mass Sol-gel silica (number average primary particle size = 110 nm) 1.0 parts by mass

[0330] (8) Preparation of developer The resulting toners (1) to (15) were mixed with carrier particles to obtain two-component developers (1) to (15) with a toner particle concentration of 8% by mass. The carrier was ferrite particles coated with acrylic resin and had an average particle size of 3.5 μm.

[0331] 2. Measurement of toner loss tangent (tanδ) T(70) As a measurement sample, 0.2 g of each of toners (1) to (15) was weighed out. Each weighed toner was press-molded in a compression molding machine at a pressure of 25 MPa to produce cylindrical pellets of each toner with a diameter of 10 mm.

[0332] The measurement device used was the ARES G2 rheometer (manufactured by TA Instruments). Disposable plates were used, with an 8 mm diameter parallel plate on top and a 20 mm diameter parallel plate on the bottom. Temperature-reducing measurements were performed at a frequency of 1 Hz. The sample was set at 100°C, and the gap was first set to 1.4 mm. Any sample protruding from the gap was then scraped off. The gap was then set to 1.1 mm, and the sample was cooled to 30°C at 10°C / min while applying axial force and held at 30°C for 30 minutes. After that, the sample was heated from 30°C to 150°C at 3°C / min, and the storage modulus (G') and loss modulus (G") were measured. The tan δ value was calculated from the relationship (loss modulus / storage modulus) at 70°C. Detailed measurement conditions are shown below.

[0333] Frequency: 1Hz Ramp rate: 3℃ / min ·Axicial force: 0g, sensitivity: 10g ·Initial strain:3.0%, Strain adjust:30.0%, Minimum strain:0.01%, Maximum strain:10.0% ·Minimum torque:1g·cm、Maximum torque:80g·cm Sampling interval: 1.0℃ / pt

[0334] 3. Image Formation The recording media used were all long media. The long media were stored in a rolled state and were pulled out from the roll when a toner image was formed. After the toner image was formed, the media was again wound into a roll and stored.

[0335] (RM1) "Pylen (registered trademark) Film P2161" (manufactured by Toyobo Co., Ltd., thickness: 50 μm, air permeability: 25,000 sec) (RM2) "Toyobo Ester (registered trademark) Film E5100" (manufactured by Toyobo Co., Ltd., thickness: 75 μm, air permeability: 23,000 sec) (RM3) "Pylen (registered trademark) Film P2161" (manufactured by Toyobo Co., Ltd., thickness: 60 μm, air permeability: 26,000 sec) (RM4) "Toyobo Ester (registered trademark) Film E5100" (manufactured by Toyobo Co., Ltd., thickness: 50 μm, air permeability: 20,000 sec) (RM5) "S9010N / 46#LF" (Avery Dennison, thickness: 190μm, air permeability 13000sec) (RM6) "NPi Foam 45" (manufactured by Nippon Paper Industries Co., Ltd., thickness: 80 μm, air permeability: 10 sec)

[0336] The image forming apparatus used was a color label machine "Accurio Label 230" (manufactured by Konica Minolta, Inc.). The color label machine was modified so that the surface temperatures of the upper fixing belt and lower fixing roller, as well as the amount of toner adhesion, could be changed. In this image forming apparatus, the recording medium was transported through the image forming apparatus in a rolled state, and after the toner image was formed, it was rewound into a roll.

[0337] A 10 cm solid image was printed on a recording medium using the same procedure as in the blocking evaluation described below. The resulting image-formed product was not rolled up, but instead cut into individual sheets. 1 cm square samples were further cut from the cut image-formed product and embedded in a photocurable resin. The embedded samples were cut in the thickness direction using a microtome with a glass knife and a diamond knife to obtain a cross-section of the image-formed product. The cross-section samples were attached vertically to the specimen stage of a scanning electron microscope (SEM) and observed at a magnification of 500x and an accelerating voltage of 0.6 kV. Three 200 μm-wide areas were randomly selected on the cross-section and examined for the presence of voids within the area. The voids were displayed in black compared to the toner-containing areas in the image layer. If voids were observed in all three areas, the result was considered "voids present." Otherwise, if no voids were observed in any of the three areas, the result was considered "voids absent."

[0338] 4. Evaluation (1) Blocking The above developers (1) to (15) were loaded in order into an image forming apparatus. The combinations of developers and recording media shown in Table VI were used, and the toner adhesion amount on the recording media was 8.0 g / m. 2 A solid image was output. The temperature of the upper fixing belt was set at a temperature (UO avoidance temperature + 25°C) 25°C higher than the temperature at which under-offset does not occur (UO avoidance temperature), and the temperature of the lower fixing roller was set at 90°C. The fixing speed was set at 230 mm / sec. A total of 1000 m of image was output onto the recording medium, and the resulting image-formed product was wound into a roll. This roll of image-formed product was removed from the winder and allowed to stand in an upright position for one day. The next day, 10 m of the image-formed product was peeled off from the roll and pulled out, and it was determined whether peeling had occurred within the image. The peeling speed was 10 cm / sec. Evaluation was based on the following criteria. A grade of C or higher (A to C) was considered acceptable.

[0339] (Evaluation criteria) A: Toner peeling was observed in 0 places, and toner blocking properties were extremely good. B: Toner peeling was observed in one location, and toner blocking properties were good. C: Toner peeling occurred in two places, and toner blocking properties were fairly good. D: Toner peeling occurs in three or more places, toner blocking occurs, and image defects occur.

[0340] (2) Fixability The above developers (1) to (15) were loaded in order into an image forming apparatus. The combinations of developers and recording media shown in Table VI were used, and the toner adhesion amount on the recording media was 8.0 g / m. 2 A solid image of 10 ...

[0341] (Evaluation criteria) A: The minimum fixing temperature is less than 130° C., and the low-temperature fixing property of the toner is extremely good. B: The minimum fixing temperature is 130° C. or higher and lower than 150° C., and the toner has good low-temperature fixing properties. C: The minimum fixing temperature is 150° C. or higher and lower than 170° C., and the low-temperature fixing property of the toner is fairly good. D: The minimum fixing temperature is 170° C. or higher, and the low-temperature fixing property of the toner is poor, making it unusable.

[0342] (3) Scratch resistance The above developers (1) to (15) were loaded in order into an image forming apparatus. The combinations of developers and recording media shown in Table VI were used, and the toner adhesion amount on the recording media was 8.0 g / m. 2A solid image of 1000 x 1000 mm was output. The temperature of the upper fixing belt was set at a temperature (UO avoidance temperature) 25°C higher than the temperature at which under-offset does not occur (UO avoidance temperature) (UO avoidance temperature + 25°C), and the temperature of the lower fixing roller was set at 90°C. The fixing speed was set at 230 mm / sec. A pencil hardness test was conducted on the output image in accordance with JIS-K5600 with a load of 750 g, and the abrasion resistance of the toner image against scratching force was evaluated according to the following evaluation criteria. A grade of C or higher (A to C) was considered acceptable.

[0343] (Evaluation criteria) A: The pencil hardness is 2H or more, and the scratch resistance of the toner image is extremely good. B: The pencil hardness is H or more and less than 2H, and the toner has good abrasion resistance. C: The pencil hardness is HB or more and less than H, and the toner has good abrasion resistance. D: The pencil hardness is less than HB, the abrasion resistance of the toner is poor, and it is unusable.

[0344] Table VI shows the evaluation and measurement results.

[0345] [Table 6]

[0346] From the examples and comparative examples, it can be seen that the toner of the present embodiment can reduce blocking when used to form images on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25° C. and a pressure of 49.03 hPa. Furthermore, from Examples 3, 12, and 14, it can be seen that blocking can be further reduced when used to form images on a recording medium having an air permeability of 25,000 sec or more.

[0347] From Examples 4 and 16, it can be seen that the toner of this embodiment has improved blocking, low-temperature fixability, and abrasion resistance because the polyester is not modified with any compound other than the monomer that forms the repeating structure.

[0348] From Examples 2 and 11, it can be seen that the toner of the present embodiment has a structure derived from methyl methacrylate, thereby reducing blocking and improving abrasion resistance.

[0349] From Examples 1 to 5, it can be seen that the toner of the present embodiment reduces blocking when the mass ratio of the styrene-(meth)acrylic resin to the polyester is within the range of 60:40 to 5:95.

[0350] From Examples 2, 6, 9 and 13, it can be seen that the toner of this embodiment reduces blocking by having the content of the release agent be 7% by mass or less with respect to the total mass of the toner base particles.

[0351] From Examples 5, 7, 8 and 10, it can be seen that the toner of the present embodiment has improved abrasion resistance when the loss tangent at 70° C. is in the range of 0.2 to 1.2. [Explanation of symbols]

[0352] 1 photoreceptor 2. Charging device 3 Exposure equipment 4. Developing device 5 Primary transfer roller 6 Cleaning Device 7 Intermediate transfer belt 8 Roller 9 Secondary transfer roller 10 Cleaning device 13 Transport roller 14 Resist Roller 15 Transport roller 50 Fixing device 61 Drawer section 62 Storage unit 63 Transport unit 64 Transport roller 65 Winding section 66 Transport Unit 67 Storage area 100 Image forming device SC Document Image Reader

Claims

1. A toner for developing electrostatic images, comprising toner base particles containing a binder resin, the binder resin contains a styrene-(meth)acrylic resin and a polyester, the mass ratio of the styrene-(meth)acrylic resin to the polyester is within a range of 80:20 to 1:99; Used for forming images on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25°C and a pressure of 49.03 hPa.

1. A toner for developing electrostatic images, comprising:

2. The styrene-(meth)acrylic resin is located inside the toner base particle, and the polyester is located outside the toner base particle.

2. The toner for developing electrostatic images according to claim 1.

3. The polyester is not modified with any compound other than the monomer that forms the repeating unit.

3. The toner for developing electrostatic images according to claim 1 or 2.

4. The polyester is not modified with the styrene-(meth)acrylic resin.

4. The toner for developing electrostatic images according to claim 3.

5. The styrene-(meth)acrylic resin has a structure derived from methyl methacrylate.

3. The toner for developing electrostatic images according to claim 1 or 2.

6. The mass ratio of the styrene-(meth)acrylic resin to the polyester is within a range of 60:40 to 5:

95.

3. The toner for developing electrostatic images according to claim 1 or 2.

7. The content of the release agent is 7% by mass or less with respect to the total mass of the toner base particles.

3. The toner for developing electrostatic images according to claim 1 or 2.

8. The toner base particles are emulsion aggregates.

3. The toner for developing electrostatic images according to claim 1 or 2.

9. The loss tangent T(70) at 70°C determined by dynamic viscoelasticity measurement is in the range of 0.2 to 1.

2.

3. The toner for developing electrostatic images according to claim 1 or 2.

10. The recording medium has an air permeability of 25,000 sec or more at a temperature of 25° C. and a pressure of 49.03 hPa.

3. The toner for developing electrostatic images according to claim 1 or 2.

11. The recording medium contains at least one of polyethylene, polypropylene, and polyethylene terephthalate.

3. The toner for developing electrostatic images according to claim 1 or 2.

12. A method for producing the toner for developing electrostatic images according to claim 1 or 2, comprising the steps of: a step of heating a dispersion of styrene-(meth)acrylic resin particles to a temperature T [°C] to grow the particle size; a step of mixing the dispersion of styrene-(meth)acrylic resin particles and the dispersion of polyester particles at a temperature T [°C] while stirring; and maintaining the mixture at a temperature T [°C] for a certain period of time while stirring the mixture. The temperature T [°C] is higher than the glass transition temperature of the styrene-(meth)acrylic resin by 30 to 40°C.

1. A method for producing a toner for developing electrostatic images, comprising:

13. 3. The toner for developing electrostatic images according to claim 1 or 2 is used to An image is formed on a long recording medium having an air permeability of 20,000 sec or more at a temperature of 25° C. and a pressure of 49.03 hPa. An image forming method comprising:

14. The image layer on the recording medium contains the toner for developing electrostatic images according to claim 1 or 2. An image-formed product characterized by the above-mentioned.

15. In a cross section in the thickness direction, the image layer has at least one void in a region having a width of 200 μm.

15. The image-formed product according to claim 14.

Images