Toner and image forming method

Abstract

A toner is provided that includes a graft polymer resin including a polyolefin resin and a styrene-based resin, a polyester resin, and a release agent. The toner satisfies the following Expressions (1) and (2): (Wk-70 / RK-70) / (Wk-50 / RK-50) ≤ 1.1... (1) 1.5 ≤ (Wk-90 / RK-90) / (Wk-50 / RK-50)... (2) where Wk-50 and RK-50 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 50°C, Wk-70 and RK-70 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 70°C, and Wk-90 and RK-90 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 90°C.

Description

FN202501093[DESCRIPTION][Title of Invention]TONER AND IMAGE FORMING METHOD[Technical Field]

[0001] The present disclosure relates to a toner and an image forming method. [Background Art]

[0002] In an electrophotographic apparatus, an electrostatic recording apparatus, or the like, an electrostatic latent image or a magnetic latent image is visualized with a toner for developing electrostatic latent images (also referred to as a "toner" in the present disclosure). For example, in the electrophotographic method, an electrostatic latent image is formed on an electrostatic latent image bearer, and then the electrostatic latent image is developed with a toner to form a toner image. When a toner image is transferred onto a recording medium such as a sheet of paper and fixed by any method such as heating, melt toner may adhere to a heating roll, fixing belt, or the like and this phenomenon is called offset. Marine transportation is one of main means for delivering toner to users, but due to the recent rise in global warming, temperatures during marine transportation are rising year by year. Thus, if the toner is in a high-temperature environment during transportation, the wax in the toner may exude to the toner surface, causing aggregation or solidification of the toner.For example, PTL 1 discloses a pulverized toner including a polyester resin and a styrene resin that is highly heat-resistant and has excellent pulverization properties, with the aim of providing a pulverized toner that can achieve both low-temperature fixability and heat- resistant storage stability.[Citation List][Patent Literature]

[0003] [PTL 1]Japanese Unexamined Patent Application Publication No. 2021-144186 [Summary of Invention] [Technical Problem]

[0004] An object of the present disclosure is to provide a toner that has both low-temperature fixability and storage stability in a high-temperature environment.[Solution to Problem]

[0005] To solve the above-described problems, an embodiment of the present disclosure provides a toner including a graft polymer resin including a polyolefin resin and a styrene -based resin, a polyester resin, and a release agent. The toner satisfies the following Expressions (1) and (2): (Wk-70 / RK-70) / (Wk-50 / RK-50) < 1.1 ... (1)FN2025010931.5 < (Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2) where Wk-50 and RK-50 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from Fourier-transform infrared spectroscopy-Attenuated total reflection (“FTIR-ATR”) measurement on the toner heated to 50°C, Wk-70 and RK-70 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 70°C, and Wk-90 and RK-90 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 90°C.[Advantageous Effects of Invention]

[0006] According to the present disclosure, a toner that has both low-temperature fixability and storage stability in a high-temperature environment is provided.[Description of Embodiments]

[0007] In describing embodiments, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.Embodiments of the present disclosure will be described in detail below. The embodiments are not limited by the following description and can be appropriately modified without departing from the scope of the present disclosure.In addition, in this specification, unless otherwise noted, "to" used for expressing a range of values means that the range includes values before and after "to" as the lower limit and the upper limit.

[0008] (Toner)The toner of the present disclosure is a toner including a graft polymer resin including a polyolefin resin and a styrene-based resin, a polyester resin, and a release agent, and the toner satisfies the following Expressions (1) and (2): (Wk-70 / RK-70) / (Wk-50 / RK-50) < 1.1 ... (1) 1.5 < (Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2) where Wk-50 and RK-50 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 50°C, Wk-70 and RK-70 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 70°C, and Wk-90 and RK-90 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 90°C.FN202501093

[0009] In the toner of the present disclosure when at a temperature of 70°C or less, most of the release agent is anchored to the graft polymer resin including the polyolefin resin and the styrene-based resin. Thus, even when the toner of the present disclosure is stored at a high temperature, exudation of the release agent to the surfaces of toner particles can be prevented, and aggregation or solidification of the toner due to high-temperature storage can be prevented. On the other hand, in the fixing temperature range for fixing the toner image on the transfer medium, the exudation effect due to the decrease in viscosity of the release agent surpasses the anchoring effect of the graft polymer resin including the polyolefin resin and styrene-based resin, on the release agent, and thus the low-temperature fixability of the toner can be ensured. In this manner, the graft polymer resin including the polyolefin resin and the styrene-based resin contributes to achieving both low-temperature fixability and storage stability in a high-temperature environment in the toner of the present disclosure.

[0010] The peak intensity derived from the release agent and the peak intensity derived from the polyester resin, which are obtained from Fourier-transform infrared spectroscopy-Attenuated total reflection (FTIR-ATR) measurement on the toner, can be measured by an appropriately selected method. For example, a method for measuring the peak intensity derived from a release agent and the peak intensity derived from a polyester resin, of a toner heated to 50°C, is as follows. For example, first, a sample is prepared by heating a toner containing a graft polymer resin including a polyolefin resin and a styrene -based resin, a polyester resin, and a release agent, to 50°C. 3 g of the toner heated to 50°C is pressed for 1 minute by applying a load of 6 t in an automatic pellet forming machine (Type M No. 50 BRP-E; manufactured by MAEKAWA TESTING MACHINE CO.) to produce a 40 mm diameter (approximately 2 mm thick) pellet. The toner pellet is subjected to attenuated total reflection (ATR) measurement by using a Fourier-transform infrared spectrometer (for example, AVATAR 370 manufactured by THERMO ELECTRON CORPORATION). This operation is repeated four times at different measurement locations on the toner pellet. The average value of the peak intensities at 2850 cm-1(a baseline of height: from 2830 cm-1to 2870 cm-1) obtained from the four operations is usable as the peak intensity Wk-50 derived from the release agent, and the average value of the peak intensities at 828 cm-1(a baseline of height: from 743 cm-1to 890 cm-1) obtained from the four operations is usable as the peak intensity RK-50 derived from the polyester resin. Here, the peak intensity at 2850 cm-1when the baseline of height is from 2830 to 2870 cm-1means that a peak in the range from 2830 cm-1to 2870 cm-1is considered as the peak intensity at 2850 cm-1. Furthermore, the peak intensity at 828 cm-1when the baseline of height is from 743 cm-1to 890 cm-1means that a peak in the range from 743 cm-1to 890 cm-1is considered as the peak intensity at 828 cm-1.

[0011] In the same manner as for the toner heated to 50°C, the peak intensities derived from the release agent and the peak intensities derived from the polyester resin of the toner heated toFN20250109370°C and the toner heated to 90°C can be measured using Fourier-transform infrared spectroscopy-Attenuated total reflection (FTIR-ATR). The "toner heated to 70°C" used in this measurement is the toner containing the graft polymer resin including the polyolefin resin and the styrene -based resin, the polyester resin, and the release agent, when heated to 70°C. The peak intensity derived from the release agent and the peak intensity derived from the polyester resin, which can be obtained from measurement on the toner heated to 70°C by using the above method or the like, are usable as Wk-70 and RK-70, respectively. Further, the "toner heated to 90°C" used in this measurement is the toner containing the graft polymer resin including the polyolefin resin and the styrene-based resin, the polyester resin, and the release agent, when heated to 90°C. The peak intensity derived from the release agent and the peak intensity derived from the polyester resin, which can be obtained from measurement on the toner heated to 90°C by using the above method or the like, are usable as Wk-90 and RK- 90, respectively.

[0012] Note that the peak intensity derived from the release agent can be set by extracting a characteristic peak from a full spectrum diagram obtained from FTIR-ATR measurement on the release agent alone. The peak intensity derived from the polyester resin can be set by extracting a characteristic peak from a full spectrum diagram obtained from FTIR-ATR measurement on the polyester resin alone.

[0013] In the toner of the present disclosure, Wk-50, Wk-70, Wk-90, RK-50, RK-70, and RK-90 satisfy the following Expressions (1) and (2).(Wk-70 / RK-70) / (Wk-50 / RK-50) < 1.1 ... (1) 1.5 < (Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2) Here, the ratio of the peak intensity derived from the release agent to the peak intensity derived from the polyester resin in the toner at a certain temperature represents the amount of the release agent on the toner surface at that temperature. Thus, (Wk-50 / RK-50) represents the amount of release agent on the toner surface at 50°C, (Wk-70 / RK-70) represents the amount of release agent on the toner surface at 70°C, and (Wk-90 / RK-90) represents the amount of release agent on the toner surface at 90°C.

[0014] In contrast to Expression (1), if (Wk-70 / RK-70) / (Wk-50 / RK-50) > 1.1 is satisfied, the amount of release agent on the toner surface at 70°C is larger than the amount of release agent on the toner surface at 50°C by more than a certain amount. This increases the exudation amount of the release agent during storage in a high-temperature environment, which may lead to aggregation or solidification of the toner. On the other hand, in contrast to Expression (2), if 1.5 > (Wk-90 / RK-90) / (Wk-50 / RK-50) is satisfied, the amount of release agent on the toner surface at 90°C is larger than the amount of release agent on the toner surface at 50°C by less than a certain amount. This decreases the exudation amount of the release agent when the toner image is fixed, which may result in poor low-temperature fixability.FN202501093

[0015] <Graft Polymer Resin Including Polyolefin Resin And Styrene-Based Resin>The toner of the present disclosure contains the graft polymer resin including the polyolefin resin and the styrene-based resin. In the toner of the present disclosure, the graft polymer resin including the polyolefin resin and the styrene-based resin acts as a dispersant for the release agent, and at 70°C or less, most of the release agent remains anchored to the graft polymer resin including the polyolefin resin and the styrene-based resin.

[0016] The content of the graft polymer including the polyolefin resin and the styrene-based resin is not particularly limited and can be appropriately selected according to a purpose, but the content of the graft polymer in the toner is preferably 0.5 mass% or more and 25 mass% or less, more preferably 1 mass% or more and 10 mass% or less, and more preferably 2 mass% or more and 5 mass% or less. When the content of the graft polymer including the polyolefin resin and the styrene-based resin in the toner is 0.5 mass% or more, sufficient anchoring effect on the release agent for preventing exudation of the release agent during storage at a high- temperature can be achieved, and the content equal to or less than 25 mass% ensures sufficient exudation of the release agent during fixing.

[0017] The polyolefin resin and styrene -based resin are not particularly limited as long as the resins can form a graft polymer, and can be appropriately selected according to a purpose.

[0018] - Polyolefin Resin -The polyolefin resin is a resin composed only of carbon and hydrogen. Example compositions of the polyolefin resin that can be used in the toner of the present disclosure preferably includes, but are not limited to, polyethylene and polypropylene.

[0019] - Styrene-based Resin -The styrene -based resin is a resin having a styrene backbone, and is a homopolymer or copolymer containing styrene or a substituted products of styrene.The styrene -based resin is not particularly limited and can be appropriately selected according to a purpose. Preferable example compositions of the styrene-based resin include, but are not limited to, polymers of styrene and substituted products of styrene such as polystyrene, poly- p-styrene, and polyvinyltoluene, styrene-a methylstyrene copolymer, styrene -p-chlorostyrene copolymer, styrene- vinyltoluene copolymer, styrene-a-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene- vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid ester copolymer, chloropolystyrene, poly a-methylstyrene, styrene / chlorostyrene copolymer, styrene / vinyl chloride copolymer, styrene / vinyl acetate copolymer, styrene / maleic acid copolymer, styrene / acrylic acid ester copolymer (e.g., styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octylFN202501093 acrylate copolymer, and styrene / phenyl acrylate copolymer), styrene / methacrylic acid ester copolymer (e.g., styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, and styrene / phenyl methacrylate copolymer), styrene / a-methyl chloroacrylate copolymer, styrene / acrylonitrile / acrylic acid ester copolymer, and styrene-a methylstyrene copolymer. One of the styrene-based resins can be used alone or two or more of the styrene-based resins can be used in combination.

[0020] < Polyester Resin>The toner of the present disclosure contains a polyester resin. As the polyester resin, polyester resins obtained by a polycondensation reaction between a generally known alcohol and a generally known carboxylic acid can be used.

[0021] Examples of the alcohol include, but are not limited to, diols, etherified bisphenols, dihydric alcohol monomers obtained by substituting these alcohols with a saturated or unsaturated hydrocarbon group having from 3 to 22 carbon atoms, and polyhydric alcohol monomers containing three or more hydroxyl groups.

[0022] Examples of the diols include, but are not limited to, ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4- propylene glycol, neopentyl glycol, and 1,4-butenediol.

[0023] Examples of etherified bisphenols include, but are not limited to, 1,4- bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, bisphenol A propylene oxide, and bisphenol A ethylene oxide.

[0024] Examples of the polyhydric alcohol monomers containing three or more hydroxyl groups include, but are not limited to, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2- methylpropanetriol, 2-methyl- 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1 ,3 ,5-trihydroxymethylbenzene.

[0025] One of the alcohols can be used alone or two or more of the alcohols can be used in combination.

[0026] Examples of the carboxylic acid include, but are not limited to, monocarboxylic acids, organic acid monomers containing two carboxylic acid groups, anhydrides of these acids, dimers of lower alkyl esters with linolenic acid, and polycarboxylic acid monomers containing three or more carboxylic acid groups.

[0027] FN202501093Examples of the monocarboxylic acids include, but are not limited to, palmitic acid, stearic acid, and oleic acid.

[0028] Examples of the organic acid monomers containing two carboxylic acid groups include, but are not limited to, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, and these acids substituted with a saturated or unsaturated hydrocarbon group having from 3 to 22 carbon atoms.

[0029] Examples of the polycarboxylic acid monomers containing three or more carboxylic acid groups include, but are not limited to, 1,2,4-benzenetricarboxylic acid, 1,2,5- benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, l,3-dicarboxyl-2-methyl- 2-methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1 ,2,7,8-octanetetracarboxylic acid ENPOL trimmer acid, and anhydrides of these acids.

[0030] One of the carboxylic acids can be used alone or two or more of the carboxylic acids can be used in combination.

[0031] The molecular weight of the polyester resin is preferably 3,500 or more and 5,500 or less, and more preferably 4,000 or more and 4,500 or less.

[0032] The molecular weight of the polyester resin can be determined from the molecular weight distribution for a THF-soluble fraction obtained by using gel permeation chromatography (GPC). A calibration curve can be created using a standard polystyrene sample.

[0033] The content of the polyester resin is not particularly limited and may be appropriately selected according to a purpose, but the content of the polyester resin in a toner base particle is preferably 70 mass% or more and 90 mass% or less, and more preferably 75 mass% or more and 85 mass% or less.

[0034] <Release Agent>The release agent contained in the toner of the present disclosure is not particularly limited and can be appropriately selected according to a purpose from release agents usable for ordinary toners, but preferably has a melting point of 70°C or more and 100°C or less. The melting point of the release agent of 70°C or more is suitable for improving storage stability in a high-temperature environment, and the melting point of 100°C or less facilitates ensuring low-temperature fixability.

[0035] FN202501093Examples of methods for measuring the melting point of the release agent in the toner include, but are not limited to, differential scanning calorimetry (DSC). For example, the melting point can be measured using the following method using a DSC system (differential scanning calorimeter) (DSC-60, manufactured by SHIMADZU CORPORATION).

[0036] About 5.0 mg of a toner as a sample is placed in an aluminum sample container. The sample container is mounted on a holder unit and set in an electric furnace. Next, the sample is heated from 20°C to 150°C at a heating rate of 10°C / min in a nitrogen atmosphere, and a DSC curve is determined using the differential scanning calorimeter (DSC-60, manufactured by SHIMADZU CORPORATION). From the obtained DSC curve, by using the analysis program in the DSC-60 system, the bottom value of a melting peak derived from the release agent can be read. Since the release agent is generally a crystalline component, the first run and second run of heating give almost the same DSC profile. Thus, the melting point of the release agent may be determined from the melting peak of the release agent obtained in the first run of heating or from the melting peak of the release agent obtained in the second run of heating. However, from the viewpoint of simplicity, it is preferable to determine the melting point from the melting peak of the release agent obtained in the first run of heating.

[0037] In the toner of the present disclosure, the endothermic peak derived from the release agent preferably has an endothermic amount of 2.0 mJ / mg or more and 3.5 mJ / mg or less, as measured in differential scanning calorimetry (DSC). When the endothermic amount of the endothermic peak derived from the release agent is 2.0 mJ / mg or more, it is suitable for improving the low-temperature fixability of the toner, and when being 3.5 mJ / mg or less, it is suitable for improving the storage stability in a high-temperature environment. The endothermic amount of the endothermic peak derived from the release agent can be determined from the DSC curve obtained by measurement using, for example, the differential scanning calorimeter (DSC-60, manufactured by SHIMADZU CORPORATION), and can be determined by calculating the peak area of the measured endothermic peak using an analysis program in the DSC-60 system or the like. The endothermic amount may be calibrated by measuring a standard sample of indium, for example. In the present disclosure, the endothermic amount of the endothermic peak derived from the release agent is represented by AH (mJ / mg).

[0038] The release agent contained in the toner of the present disclosure is not particularly limited and can be appropriately selected according to a purpose. Examples of the release agent include, but are not limited to, synthetic waxes including synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene, and polypropylene; esters, ketones, and ethers. In addition, examples of natural waxes include, but are not limited to: plant waxes such as carnauba wax, cotton wax, Japan wax, and rice wax; animal-based waxes such as beeswax and lanolin; mineral-based waxes such as ozokerite and ceresin; and petroleum waxes such asFN202501093 paraffin, microcrystalline wax, and petrolatum. Examples of the release agent further include, but are not limited to, fatty acid amide compounds such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, and chlorinated hydrocarbon; homopolymers and copolymers of polyacrylates (e.g., poly-n-stearyl methacrylate, poly-n-lauryl methacrylate), which are low-molecular-weight crystalline polymers, such as copolymer of n- stearyl acrylate and ethyl methacrylate; and crystalline polymers having a long alkyl side chain. One of the release agents can be used alone or two or more of the release agents can be used in combination.

[0039] Among these, hydrocarbon waxes such as paraffin wax, microcrystalline wax, Fischer- Tropsch wax, polyethylene wax, and polypropylene wax are preferable, and Fischer-Tropsch wax is more preferable.

[0040] The content of the release agent is not particularly limited and may be appropriately selected according to a purpose, but the content of the release agent in the toner base particle is preferably 0.5 mass% or more and 10 mass% or less, more preferably 1 mass% or more and 7 mass% or less, and more preferably 2 mass% or more and 4 mass% or less. The content of the release agent in the toner base particles of 0.5 mass% or more can ensure exhibition of the release effect during fixing, and the content of the release agent of 10 mass% or less can prevent exudation of the release agent during storage.

[0041] < Other Components >The toner of the present disclosure may contain other components in addition to the components described above. Examples of the other components include, but are not limited to, a colorant, an external additive, a charge control agent, a fluidity improver, a cleanability improver, and a magnetic material.

[0042] - Colorant -The colorant is not particularly limited and can be appropriately selected according to a purpose. Examples of the colorant include, but are not limited to, carbon black, Nigrosine dyes, black iron oxide, NAPHTHOL YELLOW S, HANSA YELLOW (10G, 5G and G), Cadmium Yellow, yellow iron oxide, loess, chrome yellow, Titan Yellow, polyazo yellow, Oil Yellow, HANSA YELLOW (GR, A, RN and R), Pigment Yellow L, BENZIDINE YELLOW (G and GR), PERMANENT YELLOW (NCG), VULCAN FAST YELLOW (5G and R), Tartrazine Lake, Quinoline Yellow Lake, ANTHRAZANE YELLOW BGL, isoindolinone yellow, red iron oxide, red lead, orange lead, cadmium red, cadmium mercury red, antimony orange, Permanent Red 4R, Para Red, Fire Red, p-chloro-o-nitroaniline red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, PERMANENT RED (F2R, F4R, FRL, FRLL and F4RH), Fast Scarlet VD, VULCAN FAST RUBINE B, Brilliant Scarlet G, LITHOL RUBINE GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B,FN202501093Bordeaux 5B, Toluidine Maroon, PERMANENT BORDEAUX F2K, HELIO BORDEAUX BL, Bordeaux 10B, BON MAROON LIGHT, BON MAROON MEDIUM, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, poly azo red, Chrome Vermilion, Benzidine Orange, perynone orange, Oil Orange, cobalt blue, cerulean blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, INDANTHRENE BLUE (RS and BC), Indigo, ultramarine, Prussian blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, cobalt violet, manganese violet, dioxane violet, Anthraquinone Violet, Chrome Green, zinc green, chromium oxide, viridian, emerald green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalocyanine Green, Anthraquinone Green, titanium oxide, zinc oxide, and lithopone. One of the colorants can be used alone or two or more of the colorants can be used in combination.

[0043] The content of the colorant is not particularly limited and can be appropriately selected according to a purpose, but the content of the colorant in the toner base particle is preferably 1 mass% or more and 15 mass% or less, and more preferably 3 mass% or more and 12 mass% or less.

[0044] - External Additive -Examples of external additives include, but are not limited to, metal oxides, silicon compounds, and other fine particles.

[0045] Examples of the metal oxide include, but are not limited to, aluminum oxide, zinc oxide, cerium oxide, and zirconium oxide. One of the metal oxides can be used alone or two or more of the metal oxides can be used in combination.

[0046] Examples of the silicon compound include, but are not limited to, silicon oxide (silica), silicon carbide, silicon nitride, and silicon tetrachloride. One of the silicon compounds can be used alone or two or more of the silicon compounds can be used in combination. Among these silicon oxides, silicon oxide (silica) is preferred.

[0047] Other examples of fine particles include, but are not limited to, fatty acid metal salts (e.g., zinc stearate, aluminum stearate, etc.), and fluoropolymers.

[0048] - Charge Control Agent -The charge control agent is not particularly limited and can be appropriately selected according to a purpose. Examples of the charge control agent include, but are not limited to, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, chelate pigments of molybdic acid, Rhodamine dyes, alkoxyamines, quaternary ammonium saltsFN202501093(including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus and phosphorus -containing compounds, tungsten and tungsten-containing compounds, fluorine activators, metal salts of salicylic acid, and metal salts of salicylic acid derivatives. Specific examples thereof include, but are not limited to: BONTRON 03 (nigrosine dye), BONTRON P-51 (quaternary ammonium salt), BONTRON S-34 (metal-containing azo dye), E-82 (metal complex of oxynaphthoic acid), E-84 (metal complex of salicylic acid), and E-89 (phenolic condensation product), which are available from ORIENT CHEMICAL INDUSTRIES CO., LTD.; TP-302 and TP-415 (molybdenum complexes of quaternary ammonium salts), which are available from HODOGAYA CHEMICAL CO., LTD.; LRA-901, and LR-147 (boron complex), which are available from JAPAN CARLIT CO., LTD.; and cooper phthalocyanine, perylene, quinacridone, azo pigments, and polymeric compounds having a functional group such as a sulfo group, a carboxyl group, and a quaternary ammonium group.

[0049] The content of the charge control agent is not particularly limited and may be appropriately selected according to a purpose, but the content of the charge control agent in the toner base particle is preferably 0.1 mass% or more and 10 mass% or less, and more preferably 0.2 mass% or more and 5 mass% or less.

[0050] - Fluidity Improver -The fluidity improver is not particularly limited and can be appropriately selected according to a purpose, as long as the fluidity improver can be used in a surface treatment to increase the hydrophobicity and prevent the deterioration of fluidity and chargeability even under high humidity. Examples of the fluidity improver include, but are not limited to, silane coupling agents, silylating agents, silane coupling agents having a fluorinated alkyl group, organic titanate coupling agents, aluminum-based coupling agents, silicone oil, and modified silicone oil. It is particularly preferable to surface-treat silica and titanium oxide with such a fluidity improver, and use the resulting hydrophobic silica and hydrophobic titanium oxide.

[0051] - Cleanability Improver -The cleanability improver is not particularly limited and can be suitably selected according to a purpose, from additives that can be added to toner to remove the developer remaining on the electrostatic latent image bearer, a primary transfer medium or the like after image transfer. Examples of the cleanability improver include, but are not limited to, metal salts of fatty acids (e.g., zinc stearate, calcium stearate, and stearic acid) and fine particles of polymers prepared by soap-free emulsion polymerization (e.g., fine particles of polymethyl methacrylate and polystyrene). The polymer fine particles preferably have a relatively narrow particle size distribution, and preferably have the volume average particle diameter of from 0.01 pm to 1 pm.

[0052] - Magnetic Material -FN202501093The magnetic material is not particularly limited and can be appropriately selected according to a purpose. Examples of the magnetic material include, but are not limited to, iron powder, magnetite, and ferrite. Among these magnetic materials, a white magnetic material is preferred in terms of color tone.

[0053] <Method for Producing Toner>The toner of the present disclosure may be produced by mixing the above-mentioned components, and performing kneading, pulverization and classification to obtain toner particles having desired particle diameters. The toner of the present disclosure may also be produced by using the toner particles as toner base particles, and in such a case, the toner base particles may be mixed with an external additive such as inorganic fine particles.

[0054] Specifically, for example, the above-described components are premixed in a mixer such as a Henschel mixer, and then the materials are thoroughly kneaded using a twin-screw extruder such as a KTK-type twin-screw extruder manufactured by KOBE STEEL, LTD., a TEM-type twin-screw extruder manufactured by TOSHIBA MACHINE CO., LTD., a PCM-type twin- screw extruder manufactured by IKEGAI CO., LTD., and a KEX-type twin-screw extruder manufactured by KURIMOTO LTD., or a continuous-type single-screw kneader such as a cokneader manufactured by BUSS AG and a thermal kneader such as kneaders manufactured by KCK Company. In the kneading, to increase the specific energy, a method in which kneading processing amount is reduced, or a method in which the materials are kneaded in a high viscosity state by using a low set temperature of the kneader.

[0055] Next, the kneaded material is cooled, pulverized into coarse particles using a hammer mill or the like, and then pulverized into fine particles on a fine pulverizer using a jet stream or a mechanical fine pulverizer. The finely pulverized material is subsequently classified to the predetermined particle size using a classifier that utilizes swirling airflow or a classifier that utilizes the Coanda effect.

[0056] In the classification, a fine particle portion may be separated by using a cyclone, a decanter, or centrifugal separation, for example.

[0057] After the pulverization and classification, the pulverized product may be classified in an airflow by a centrifugal force, thus preparing toner particles having predetermined particle diameters.

[0058] The weight average particle diameter of the resulting toner particles is preferably from 4 pm to 10 pm, and more preferably from 5 pm to 8 pm. The weight average particle diameter can be measured, for example, using a measuring device for measuring the particle size distribution of toner particles by using the Coulter counter method. Examples of theFN202501093 measuring device include, but are not limited to, COULTER MULTISIZER 4e (manufactured by BECKMAN COULTER, INC.).

[0059] (Developer)The developer using the toner of the present disclosure may be a one-component developer or a two-component developer. For example, a two-component developer includes the toner of the present disclosure and a carrier.The carrier is not particularly limited and can be appropriately selected according to a purpose. Preferably, the carrier includes a core material and a resin layer coating the core material.

[0060] The material of the core material is not particularly limited and can be appropriately selected according to a purpose. Preferred examples thereof include, but are not limited to, manganese- strontium (Mn-Sr) materials and manganese-magnesium (Mn-Mg) materials of 50 emu / g or more and 90 emu / g or less. For securing image density, high magnetization materials such as iron powders (100 emu / g or more) and magnetites (75 emu / g or more and 120 emu / g or less) are preferred. Additionally, low magnetization materials such as copperzinc (Cu-Zn) materials (30 emu / g or more and 80 emu / g or less) are preferred for improving image quality, because such materials can weaken the contact between the toner and an electrostatic latent image bearer when the toner is in a standing state. One of the materials can be used alone or two or more of the materials can be used in combination.

[0061] The volume average particle diameter of the core material is preferably 25 pm or more and 200 pm or less.

[0062] The material of the resin layer is not particularly limited and can be appropriately selected according to a purpose. Examples of the material of the resin layer include, but are not limited to, amino resins, polyvinyl resin, polystyrene resin, halogenated olefin resins, polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymers of vinylidene fluoride and an acrylic monomer, copolymers of vinylidene fluoride and vinyl fluoride, fluoro terpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride, and a non-fluorinated monomer, and silicone resins. One of the materials can be used alone or two or more of the materials can be used in combination.

[0063] The mixing ratio of the toner to the carrier in a two-component developer is preferably 2.0 mass% or more and 12.0 mass% or less, and more preferably 2.5 mass% or more and 10.0 mass% or less.

[0064] (Toner Storage Unit)FN202501093In the present disclosure, a toner storage unit includes a unit having a function of storing toner and the toner of the present disclosure stored in the unit. Example forms of the toner storage unit include, but are not limited to, a toner storage container, a developing unit, and a process cartridge.The toner storage container refers to a container storing the toner.The developing unit refers to a unit including a means for storing and developing the toner. The process cartridge refers to a combined unit of an image bearer and a developing means that stores the toner and is detachably mountable on an image forming apparatus. The process cartridge may further include at least one selected from a charging means, an irradiation means, and a cleaning means.The toner storage unit of the present disclosure stores the toner of the present disclosure, and the toner can be easily supplied from the toner storage unit to the image forming apparatus, because aggregation or solidification of the toner is suppressed.

[0065] < Process Cartridge>The process cartridge according to an embodiment of the present disclosure includes an electrostatic latent image bearer that bears an electrostatic latent image and a developing means that develops, with toner, the electrostatic latent image on the electrostatic latent image bearer to form a visible image. The process cartridge may further include optional other means, such as a charging means, an irradiation means, a developing means, a transfer means, a cleaning means, and a static elimination means.The developing means includes a developer storing container storing the toner or developer according to an embodiment of the present disclosure, and a developer bearer that bears and conveys the toner or developer stored in the developer storing container. The developing means may further include a layer thickness regulator that regulates the layer thickness of the toner borne, for example.The process cartridge of the present disclosure is detachably mountable on various electrophotographic apparatuses, facsimile machines, and printers. Preferably, the process cartridge is detachably mounted on an image forming apparatus of the present disclosure described later.

[0066] (Image Forming Apparatus)The image forming apparatus according to the present disclosure includes an electrostatic latent image bearer, an electrostatic latent image forming means that forms an electrostatic latent image on the electrostatic latent image bearer, a developing means that develops the electrostatic latent image formed on the electrostatic latent image bearer with the toner of the present disclosure to form a toner image, a transfer means that transfers the toner image onto a transfer medium and a fixing means that fixes the transferred image transferred on a surface of the transfer medium, and may further include other components as necessary.

[0067] FN202501093In addition to the electrostatic latent image bearer, the electrostatic latent image forming means, the developing means, the transfer means, and the fixing means described above, the image forming apparatus according to the present disclosure can include other means such as a static elimination means, a cleaning means, a recycling means, and a control means.

[0068] The developing means may form a toner image by using a developer containing the toner of the present disclosure and optionally further containing other components.

[0069] <Electrostatic Latent Image Bearer>The material, shape, structure, size, and the like of the electrostatic latent image bearer are not particularly limited and can be appropriately selected from known materials, shapes, structures, sizes, and the like. Examples of the material of the electrostatic latent image bearer include, but are not limited to, inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors (OPCs) such as polysilane and phthalopolymethine.

[0070] The shape of the electrostatic latent image bearer is not particularly limited and can be appropriately selected according to a purpose, but a cylindrical shape is preferred. The outer diameter of the cylindrical electrostatic latent image bearer is not particularly limited and can be appropriately selected according to a purpose, but is preferably from 3 mm to 100 mm, more preferably from 5 mm to 50 mm, and most preferably from 10 mm to 30 mm.

[0071] <Electrostatic Latent Image Forming Means >An electrostatic latent image forming means is not particularly limited as long as the electrostatic latent image forming unit is a means for forming an electrostatic latent image on an electrostatic latent image bearer, and can be appropriately selected according to a purpose. For example, the electrostatic latent image forming means can include a charger that is a charging member that uniformly charges the surface of the electrostatic latent image bearer, and an irradiator that is an irradiation means that irradiates the surface of the electrostatic latent image bearer with light to form an image.

[0072] The charger is not particularly limited and can be appropriately selected according to a purpose. Examples of the charger include, but are not limited to, contact chargers equipped with a conductive or semiconductive roller, brush, film, or rubber blade and non-contact chargers employing corona discharge such as corotron and scorotron.

[0073] The charger may be in any form selected from a roller, a magnetic brush, a fur brush, and the like, and can be selected according to the specifications and configurations of the image forming apparatus.

[0074] FN202501093The charger is preferably a charger that is arranged in contact with or not in contact with the electrostatic latent image bearer and charges the surface of the electrostatic latent image bearer by applying DC and AC voltages in a superimposed manner. Further, it is preferable that the charger is a charging roller arranged in a non-contact manner close to the electrostatic latent image bearer by using a gap tape, and charging of the surface of the electrostatic latent image bearer is performed by applying DC and AC voltages in a superimposed manner to the charging roller.

[0075] The charger is not limited to the contact-type charger, but it is preferable to use a contact-type charging member, because it is possible to obtain an image forming apparatus in which the amount of ozone generated from the charger is reduced.

[0076] The irradiator is not particularly limited and can be appropriately selected according to a purpose, as long as the irradiator can irradiate, with light, the surface of the electrostatic latent image bearer charged by the charger to form an image to be formed. Examples of the irradiator include, but are not limited to, copying optical systems, rod lens array systems, laser optical systems, and liquid crystal shutter optical systems.

[0077] The light source used for the irradiator is not particularly limited and can be appropriately selected according to a purpose. Examples of the light source include, but are not limited to, general light-emitting devices such as fluorescent lights, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light-emitting diodes (LEDs), semiconductor lasers (LDs), and electroluminescence (EL) sources.

[0078] To emit light in a desired wavelength region only, various types of filters can be used, such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter.

[0079] The irradiator may use a back-light method in which the electrostatic latent image bearer is irradiated with light from the back side such that an image is formed.

[0080] <Developing Means>The developing means is not particularly limited as long as the developing means can develop the electrostatic latent image formed on the electrostatic latent image bearer to form a toner image, and can be appropriately selected according to a purpose. For example, a suitable developing means may include a developing unit that stores the toner and can apply the toner to the electrostatic latent image in a contact or non-contact manner, and a developing unit that includes a container containing toner is preferable.

[0081] FN202501093The developing unit may be a monochrome developing unit or a multicolor developing unit. Suitable examples of the developing unit include, but are not limited to, a developing device including a stirrer that frictionally stirs the toner to charge the toner, and a rotatable developer bearer, such as a magnet roller, including a magnetic field generating unit fixed on the inside and for carrying a developer including the toner on a surface.

[0082] <Transfer Means>Preferably, the transfer means includes a primary transfer means that transfers a toner image onto an intermediate transfer body to form a composite transfer image, and a secondary transfer means that transfers the composite transfer image onto a transfer medium. The intermediate transfer body is not particularly limited and can be appropriately selected from known transfer bodies according to a purpose. Preferred examples of the intermediate transfer body include, but are not limited to, a transfer belt.

[0083] The transfer means (the primary transfer means and the secondary transfer means) preferably includes at least a transferrer that peels and charges the toner image formed on the electrostatic latent image bearer onto the transfer medium. The number of the transfer means may be one, or two or more.

[0084] Examples of the transferrer include, but are not limited to, a corona transferrer using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transferrer.

[0085] A typical example of the transfer medium is a sheet of plain paper. However, the transfer medium is not particularly limited and can be appropriately selected from known transfer media such as recording paper according to a purpose, as long as the transfer medium can receive an unfixed image after development. For example, a PET base for overhead projectors (OHP) can also be used.

[0086] <Fixing Means >The fixing means is not particularly limited and can be appropriately selected according to a purpose. However, a known heating and pressing unit is suitable. Examples of the heating and pressing unit include, but are not limited to, a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller, and an endless belt.

[0087] The fixing means is preferably a heating and pressing unit that includes a heating element with a heat generating element, a film in contact with the heating element, and a pressing member in pressure contact with the heating element via the film, and a transfer medium on which an unfixed image is formed can be pressure-fixed by being passed between the film and the pressing member.FN202501093

[0088] Typically, the heating temperature in the heating and pressing unit is preferably from 80°C to 200°C.

[0089] The surface pressure at the heating and pressing unit is not particularly limited and can be appropriately selected according to a purpose, but is preferably from 10 N / cm2to 80 N / cm2.

[0090] Note that, in the present embodiment, according to a purpose, a known optical fixer may be used together with or instead of the fixing unit, for example.

[0091] < Other Means >The image forming apparatus of the present disclosure can include other means such as a static elimination means, a cleaning means, a recycling means, and a control means.

[0092] <Static Elimination Means>The static elimination means is not particularly limited and can be appropriately selected from known static eliminators as long as the static eliminator can apply a static elimination bias to the electrostatic latent image bearer. Preferred examples thereof include, but are not limited to, a static elimination lamp.

[0093] <<Cleaning Means>>The cleaning means can be any means that can remove the toner remaining on the electrostatic latent image bearer, and can be appropriately selected from among known cleaners. Examples of the cleaning means include, but are not limited to, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a brush cleaner, and a web cleaner.

[0094] When the image forming apparatus of the present disclosure has the cleaning means, the cleaning performance can be improved. That is, by controlling the adhesive force between toner particles, the fluidity of the toner can be controlled, and the cleaning performance can be improved. Furthermore, by controlling the properties of the deteriorated toner, it is possible to maintain excellent cleaning quality even under severe conditions such as a long life or high temperature and humidity. Furthermore, since the external additive can be sufficiently liberated from the toner on the electrostatic latent image bearer, a deposition layer (dam layer) of the external additive can be formed in the cleaning blade nip portion, which makes it possible to achieve a high cleaning performance.

[0095] <Recycling Means>The recycling means is not particularly limited, and examples thereof include, but are not limited to, known conveyance means.FN202501093

[0096] <<Control Means »The control means can control the operation of each of the above-described units. The control means is not particularly limited and can be appropriately selected according to a purpose, as long as the control means can control the operation of each of the means described above. Examples of the control means include, but are not limited to, control devices such as a sequencer and a computer.

[0097] (Image Forming Method)An image forming method according to the present disclosure includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image bearer, a developing step of developing the electrostatic latent image formed on the electrostatic latent image bearer with the toner of the present disclosure to form a toner image, a transfer step of transferring the toner image onto a transfer medium, and a fixing step of fixing the toner image transferred on the transfer medium.

[0098] The image forming method of the present disclosure can further include other optional steps such as a static elimination step, a cleaning step, a recycling step, and a control step.

[0099] <Electrostatic Latent Image Forming Step>The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image bearer, and can include a charging step of charging the surface of the electrostatic latent image bearer, and an irradiating step of irradiating, with light, the charged surface of the electrostatic latent image bearer to form an electrostatic latent image. The charging can be performed by, for example, applying a voltage to the surface of the electrostatic latent image bearer by the charger. The irradiation can be performed, for example, by using the irradiator to irradiate, with light, the surface of the electrostatic latent image bearer to form an image, and specifically, irradiating, with light, the surface of the electrostatic latent image bearer to form an image can be based on image data. The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image bearer and then irradiating, with light, the surface to form an image, and can be performed by the electrostatic latent image forming means.

[0100] < Developing Step>The developing step is a step of developing the electrostatic latent image with the toner to form a toner image. For example, formation of the toner image can be performed by using the toner of the present disclosure to develop the electrostatic latent image, and can be performed by the developing unit. Note that a plurality of toners with different colors may be used for development.

[0101] FN202501093For example, in the developing unit, the toner is stirred, and the toner is charged by friction during the stirring, and is maintained in an upright state on the surface of a rotating magnet roller, to form a magnetic brush. The magnet roller is disposed in the vicinity of the electrostatic latent image bearer. Thus, a part of the toner of the magnetic brush formed on the surface of the magnet roller moves to the surface of the electrostatic latent image bearer by electric attraction. As a result, the electrostatic latent image is developed by the toner, and a toner image is formed on the surface of the electrostatic latent image bearer.

[0102] <Transfer Step>The transfer step is a step of transferring the toner image onto a transfer medium. It is preferable that an intermediate transfer body is used in the transfer step, transfer of the toner image onto the intermediate transfer body is performed as a primary transfer, and then transfer of the toner image onto the transfer medium is performed as a secondary transfer. It is more preferable that, the transfer step includes a primary transfer step of using two or more toners having different colors, preferably full color toners, to transfer a toner image onto the intermediate transfer body, to form a composite transfer image, and a secondary transfer step of transferring the composite transfer image onto a transfer medium. The transfer can be performed by charging the toner image onto the electrostatic latent image bearer by using a transfer charger, for example. The transfer step can be preferably performed by the transfer means.

[0103] <Fixing Step>The fixing step is a step of fixing, by using a fixing device, the toner image transferred to the transfer medium, and may be performed each time transfer onto the transfer medium using a developer with a different color is performed, or may be performed simultaneously for the developers with different colors in a superimposed state.

[0104] < Other Steps>The image forming method of the present disclosure can further include other steps appropriately selected as necessary, such as a static elimination step, a cleaning step, a recycling step, and a control step.

[0105] <<Static Elimination Step>>The static elimination step is a step of applying a static elimination bias to the electrostatic latent image bearer to eliminate static electricity, and can be preferably performed by a static elimination unit.

[0106] <<Cleaning Step>>The cleaning step is a step of removing the toner remaining on the electrostatic latent image bearer, and is preferably performed by the cleaning means.FN202501093

[0107] << Recycling Step>>The recycling step is a step of recycling the toner removed in the cleaning step, for the developing means, and is preferably performed by the recycling means.

[0108] <<Control Step>>The control step is a step of controlling the operation of each of the above-described means, and can be preferably performed by the control means.[Examples]

[0109] Hereinafter, the embodiments will be described in more detail with reference to examples and comparative examples, but the embodiments of the present disclosure are not limited to these examples and comparative examples.

[0110] <Synthesis of Resin A>Into an autoclave reaction tank equipped with a stirring rod, a nitrogen inlet tube, and a thermometer, 368 parts by mass of xylene and 158 parts by mass of an ethylene -propylene copolymer (softening point 74°C) were placed, and heated to 165°C. Then, 55 parts by mass of t-butyl peroxybenzoate as a polymerization initiator was dissolved in a mixture of 846 parts by mass of styrene, 32 parts by mass of 2-ethylhexyl acrylate, and 15 parts by mass of maleic anhydride, and the mixture was added dropwise to the mixture in the autoclave reaction tank over 5 hours while stirring. The mixture was then stirred for an additional hour. Next, the solvent was removed and Resin A was obtained.

[0111] <Synthesis of Resin B>A monomer mixture containing 45 mol% of polyoxypropylene (2.2)-2,2-bis(4- hydroxyphenyl)propane (hereinafter abbreviated as "BPA-PO") and 30 mol% of sebacic acid, which is a raw material monomers for a polyester resin, was placed in a 5 -liter autoclave reaction tank equipped with a distillation column so that the total amount was 4000 g, and 5 g of dibutyltin oxide was added as an esterification catalyst. Polycondensation reaction of the mixture was carried out at 230°C for 6 hours in a nitrogen atmosphere, and then the reaction mixture was cooled to 160°C. Then, a mixture containing 15 mol% of styrene and 10 mol% of acrylic acid, as raw material monomers for an addition polymerization resin, and 25 g of di-tert-butyl peroxide as a polymerization initiator, was added dropwise to the reaction mixture in the autoclave reaction tank over 1 hour while stirring at 160°C. Then, addition polymerization reaction of the mixture was carried out at 160°C for another hour. Then, condensation polymerization reaction of the mixture was carried out by heating the mixture to 200°C. As a result, Resin B was obtained.

[0112] <Synthesis of Polyester Resin C>FN202501093A reaction tank was equipped with a cooling tube, a stirrer, and a nitrogen inlet tube. The monomer species presented in Table 1 below and tetrabutoxy titanate as a condensation catalyst were placed in the reaction tank and the mixture was allowed to react at 230°C for 6 hours, while removing the generated water by distillation under a nitrogen stream. Next, the mixture was allowed to react for 1 hour under a reduced pressure of 5 mmHg to 20 mmHg. As a result, a polyester resin C was obtained. In Table 1, "25 mol%" indicated for bisphenol A (2,2) propylene oxide (25 mol%) and bisphenol A (2,2) ethylene oxide (25 mol%) expresses the proportion in the alcohol component when the acid component is 50 mol% and the alcohol component is 50 mol%.

[0113] [Table 1]

[0114] (Example 1)- Preparation of Toner Base Particles -Polyester resin C: 84 parts by massFischer-Tropsch wax (release agent) (FNP-0090, NIPPON SEIRO CO., LTD.): 2.0 parts by massResin A (dispersant for release agent): 2.0 parts by massCarbon black (colorant) (#44, manufactured by MITSUBISHI CHEMICAE CORP.): 11 parts by massAzo-iron compound (charge control agent) (T-77, manufactured by HODOGAYA CHEMICAL CO., LTD.): 1 part by mass

[0115] The raw materials of the toner base particles were premixed by using a Henschel mixer (FM20B, manufactured by MITSUI MIIKE KAKOKI CO., LTD.), and then melted and kneaded at a temperature of 120°C by using a twin-screw kneader (PCM-30, manufactured by IKEGAI CO., LTD.). The obtained kneaded product was rolled by a roller to have a thickness of 2.7 mm, and the resulting roll was cooled to room temperature by a belt cooler and pulverized into coarse particles having a diameter of from 200 to 300 pm by a hammer mill.

[0116] The pulverized coarse particles of the kneaded product were further pulverized into fine particles by a supersonic jet mill LABO JET (manufactured by NIPPON PNEUMATIC MFG.FN202501093CO., LTD.). The fine particles were classified by size using an air classifier (MDS-I manufactured by NIPPON PNEUMATIC MFG. CO., LTD.) while appropriately adjusting the opening of the louver to achieve the weight average particle diameter of 5.8 ± 0.2 pm. Thus, toner base particles were prepared.

[0117] - Preparation of Toner -To 100 parts by mass of the obtained toner base particles, 1.0 part by mass of silica (HDK- 2000, manufactured by CLARIANT AG) and 1.0 part by mass of silica (H05TD, manufactured by CLARIANT AG) were added as external additives, and the mixture was stirred and mixed in a Henschel mixer to prepare a toner.

[0118] The toners of Examples 2 to 10 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that the types and amounts of the release agent and dispersant were changed to those presented in Table 2. In Examples 1 to 10 and Comparative Examples 1 to 3, one of Fischer-Tropsch waxes (FNP-0090, NIPPON SEIRO CO., LTD., FT-115H, NIPPON SEIRO CO., LTD., SX-105, NIPPON SEIRO CO., LTD., or FT-165, NIPPON SEIRO CO., LTD.), a paraffin wax (HNP-9, NIPPON SEIRO CO., LTD.), and a carnauba wax was used as the release agent.

[0119] [Table 2]FN202501093

[0120] <Measurement of Melting Point of Release Agent And Endothermic Amount of Endothermic Peak Derived from Release Agent>The melting point of the release agent used in the toner of Example 1 was measured according to the following method by using a DSC system (differential scanning calorimeter) (DSC-60, manufactured by SHIMADZU CORPORATION).

[0121] About 5.0 mg of the toner of Example 1 was placed in an aluminum sample container. The sample container was mounted on a holder unit and set in an electric furnace. Next, the toner was heated from 20°C to 150°C at a heating rate of 10°C / min in a nitrogen atmosphere, and a DSC curve was determined using the differential scanning calorimeter (DSC-60, manufactured by SHIMADZU CORPORATION). From the obtained DSC curve, by using the analysis program in the DSC-60 system, the bottom value of a melting peak derived from the release agent was read using the analysis program in the DSC-60 system to determine the melting point of the release agent. The endothermic amount AH (mJ / mg) of the endothermic peak derived from the release agent was determined by calculating, with an analysis program in the DSC-60 system and the like, the peak area of the endothermic peak derived from the release agent in the DSC curve obtained by differential scanning calorimetry (DSC).

[0122] In the same manner as in Example 1, the melting points of the release agents used in the toners of Examples 2 to 10 and Comparative Examples 1 to 3 and the endothermic amounts of the endothermic peaks derived from the release agents from differential scanning calorimetry (DSC) measurement were measured. The endothermic amount of the endothermic peak derived from the release agent was determined from the DSC curve obtained by measurement using, for example, the differential scanning calorimeter (DSC-60, manufactured by SHIMADZU CORPORATION), and was determined by calculating the peak area of the measured endothermic peak using an analysis program in the DSC-60 system or the like. The endothermic amount was calibrated based on measurement of a standard sample of indium. The endothermic amount of the endothermic peak derived from the release agent was denoted as AH (mJ / mg). The results are presented in Table 3.

[0123] <Measurement Using Fourier-transform Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR) Method>- Toner Heated to 50°C -FN202501093A method for measuring, by using Fourier-transform infrared spectroscopy-Attenuated total reflection (FTIR-ATR), the peak intensity derived from the release agent and the peak intensity derived from the polyester resin, of the toner of Example 1 heated to 50°C, was as follows. First, a sample was prepared by heating the toner containing the graft polymer resin including the polyolefin resin and the styrene-based resin, the polyester resin, and the release agent, to 50°C. 3 g of the toner heated to 50°C was pressed for 1 minute by applying a load of 6 t in an automatic pellet forming machine (Type M No. 50 BRP-E; manufactured by MAEKAWA TESTING MACHINE CO.) to produce a 40 mm diameter (approximately 2 mm thick) pellet. The toner pellet was subjected to attenuated total reflection (ATR) measurement by using a Fourier-transform infrared spectrometer (AVATAR 370 manufactured by THERMO ELECTRON CORPORATION). The peak intensity at 2850 cm-1(a baseline of height: from 2830 cm-1to 2870 cm-1) was used as the peak intensity derived from the release agent, and the peak intensity at 828 cm-1(a baseline of height: from 743 cm-1to 890 cm-1) was uses as the peak intensity derived from the polyester resin. Each peak intensity was measured four times at different measuring locations on the toner pellet. The average values of the peak intensities were calculated as the peak intensity Wk-50 derived from the release agent and the peak intensity RK-50 derived from the polyester resin. Here, the peak intensity at 2850 cm-1when the baseline of height is from 2830 to 2870 cm-1means that a peak in the range from 2830 cm-1to 2870 cm-1is considered as the peak intensity at 2850 cm-1. Furthermore, the peak intensity at 828 cm-1when the baseline of height is from 743 cm-1to 890 cm-1means that a peak in the range from 743 cm-1to 890 cm-1is considered as the peak intensity at 828 cm-1.

[0124] Note that the peak intensity derived from the release agent was set by extracting a characteristic peak from a full spectrum diagram obtained from FTIR-ATR measurement on the release agent alone. The peak intensity derived from the polyester resin was determined from the peak derived from the benzene ring of the polyester resin.

[0125] - Toner Heated to 70°C -For the toner of Example 1 heated to 70°C, the peak intensity derived from the release agent and the peak intensity derived from the polyester resin were measured by using the FTIR- ATR in the same manner as for the toner heated to 50°C. Each peak intensity was measured four times at different measuring locations on the toner pellet. The average values of the peak intensities were calculated as the peak intensity Wk-70 derived from the release agent and the peak intensity RK-70 derived from the polyester resin.

[0126] -Toner heated to 90°C-For the toner of Example 1 heated to 90°C, the peak intensity derived from the release agent and the peak intensity derived from the polyester resin were measured by using the FTIR- ATR in the same manner as for the toner heated to 50°C. Each peak intensity was measuredFN202501093 four times at different measuring locations on the toner pellet. The average values of the peak intensities were calculated as the peak intensity Wk-90 derived from the release agent and the peak intensity RK-90 derived from the polyester resin.

[0127] By plugging, into the following Expressions (1) and (2), the values of the peak intensities Wk-50, Wk-70, and Wk-90 derived from the release agent and the values of the peak intensities RK-50, RK-70, and RK-90 derived from the polyester resin, of the toner of Example 1, which were obtained by the above measurements, values of Expressions (1) and (2) were calculated.(Wk-70 / RK-70) / (Wk-50 / RK-50) ... (1)(Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2)

[0128] For the toners of Examples 2 to 10 and Comparative Examples 1 to 3, values of peak intensities Wk-50, Wk-70, and Wk-90 derived from the release agent and values of peak intensities RK-50, RK-70, and RK-90 derived from the polyester resin, of each toner were determined in the same manner as in Example 1, and were plugged into the Expressions (1) and (2) to calculate values of Expressions (1) and (2). The results are presented in Table 3.

[0129] [Table 3]

[0130] The toners of Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated for low- temperature fixability and storage stability in a high-temperature environment using evaluation methods described below.

[0131] Evaluation of Low-temperature Fixability >FN202501093Each of the toners of Examples 1 to 10 and Comparative Examples 1 to 3 was placed in a toner storage container of a copier (RICOH MPC 6003) manufactured by RICOH COMPANY, LTD. A solid image was formed on a sheet of paper (RICOH COMPANY, LTD., Type 6200) using a method including an electrostatic latent image forming step (including an irradiating step) and a developing step, followed by transfer of the solid image onto the sheet with an adhesion amount of 0.4 mg / cm2(the transfer step) and fixation of the solid image (the fixing step). The linear speed used in fixing the toner image was 256 mm / sec. The image formation onto the sheet was performed while changing fixing temperature in the fixing step in increments of 5°C, to measure the lowest temperature at which cold offset did not occur (a lowest fixing temperature). The low-temperature fixability was evaluated according to the following evaluation criteria. The results are presented in Table 4. The NIP width in a fixing means was 11 mm.

[0132] - Evaluation Criteria for Low-temperature Fixability - A: Less than 125°CB: 125°C or more and lower than 135°CC: 135°C or more

[0133] Evaluation of Storage Stability in High-Temperature EnvironmentThe toners of Examples 1 to 10 and Comparative Examples 1 to 3 were left to stand at 50°C for 6 hours, and the penetration was measured in accordance with JIS K2235 (25°C). The storage stability in a high-temperature environment was evaluated according to the following evaluation criteria. The results are presented in Table 4. A penetrometer VR-5610 (SHIMADZU CORPORATION) was used as a penetration measurement device.

[0134] - Evaluation Criteria for Storage Stability in High-Temperature Environment - A: 22 mm or moreB: 20 mm or more and less than 22 mmC: Less than 20 mm

[0135] [Table 4]FN202501093

[0136] Toners that were graded "A" or "B" for low-temperature fixability and "A" or "B" for storage stability in a high-temperature environment were determined to be applicable as the present disclosure.

[0137] Examples 1 to 10 were graded "A" or "B" for low-temperature fixability, and "A" or "B" for storage stability in a high-temperature environment.

[0138] The toner of Comparative Example 1 had a value of Expression (2) smaller than 1.5, and thus the amount of exudation of the release agent during fixture of the toner image was reduced. As a result, the low-temperature fixability of Comparative Example 1 was graded "C".

[0139] The toner of Comparative Example 2 had a value of Expression (1) larger than 1.1, and thus the amount of exudation of the release agent in a high-temperature environment increased. As a result, the storage stability in a high-temperature environment of Comparative Example 2 was graded "C".

[0140] The toner of Comparative Example 3 that did not include a graft polymer resin including a polyolefin resin and a styrene-based resin, could suppress the exudation of the release agent in a high-temperature environment, but had a reduced amount of exudation of the release agent during fixture of the toner image. As a result, the low-temperature fixability of the toner of Comparative Example 3 was graded "C", and the toner failed to achieve both low-temperature fixability and storage stability in a high-temperature environment.

[0141] From the above, it has been demonstrated that the toner according to the present disclosure had both low-temperature fixability and storage stability in a high-temperature environment.

[0142] Aspects of the present disclosure include the following, for example.According to Aspect 1, a toner includes a graft polymer resin including a polyolefin resin and a styrene-based resin, a polyester resin, and a release agent, and the toner satisfies the following Expressions (1) and (2),(Wk-70 / RK-70) / (Wk-50 / RK-50) < 1.1 ... (1)1.5 < (Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2) where Wk-50 and RK-50 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 50°C,FN202501093Wk-70 and RK-70 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 70°C, and Wk-90 and RK-90 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 90°C. According to Aspect 2, in the toner of Aspect 1, the release agent has a melting point of 70°C or more and 100°C or less, and an endothermic amount of an endothermic peak derived from the release agent is 2.0 mJ / mg or more and 3.5 mJ / mg or less, as measured using differential scanning calorimetry (DSC). According to Aspect 3, in the toner of Aspect 1 or Aspect 2, the release agent includes a hydrocarbon wax.According to Aspect 4, in the toner of Aspect 3, the hydrocarbon wax includes a Fischer- Tropsch wax.According to Aspect 5, an image forming method includes: forming an electrostatic latent image on an electrostatic latent image bearer, developing, by using the toner of any one of Aspect 1 to Aspect 4, the electrostatic latent image formed on the electrostatic latent image bearer to form a toner image, transferring the toner image onto a transfer medium, and fixing the toner image transferred on the transfer medium.

[0143] The toners according to Aspects 1 to 4 and the image forming method according to Aspect 5 make it possible to solve the problems in the related art and achieve the object of the present disclosure.

[0144] The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments may be combined with each other and / or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.

[0145] This patent application is based on and claims priority to Japanese Patent Application No. 2024-205471, filed on November 26, 2024, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

Claims

FN202501093[CLAIMS]1. A toner comprising: a graft polymer resin including a polyolefin resin and a styrene-based resin; a polyester resin; and a release agent, wherein the toner satisfies the following Expressions (1) and (2), (Wk-70 / RK-70) / (Wk-50 / RK-50) < 1.1 ... (1)1.5 < (Wk-90 / RK-90) / (Wk-50 / RK-50) ... (2) where Wk-50 and RK-50 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 50°C,Wk-70 and RK-70 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 70°C, andWk-90 and RK-90 are peak intensities derived from the release agent and the polyester resin, respectively, and obtained from FTIR-ATR measurement on the toner heated to 90°C.

2. The toner according to claim 1, wherein the release agent has a melting point of 70°C or more and 100°C or less, and an endothermic amount of an endothermic peak derived from the release agent is 2.0 mJ / mg or more and 3.5 mJ / mg or less, as measured using differential scanning calorimetry.

3. The toner according to claim 1 or 2, wherein the release agent comprises a hydrocarbon wax.

4. The toner according to claim 3, wherein the hydrocarbon wax comprises a Fischer-Tropsch wax.

5. An image forming method, comprising: forming an electrostatic latent image on an electrostatic latent image bearer; developing, by using the toner according to any one of claims 1 to 4, the electrostatic latent image formed on the electrostatic latent image bearer to form a toner image; transferring the toner image onto a transfer medium; and fixing the toner image transferred on the transfer medium.

Images