Toner for electrostatic charge image development, electrostatic charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method

Abstract

To provide a toner for electrostatic charge image development that is excellent in discoloration prevention properties in an image to be obtained.SOLUTION: A toner for electrostatic charge image development has toner particles including a binder resin, a colorant, and a ferulic acid ester compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a toner for developing electrostatic images, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. [Background technology]

[0002] Patent Document 1 discloses an ultraviolet-absorbing polymer composition characterized by comprising a polymer containing γ-oryzanol.

[0003] Patent Document 2 discloses a recording medium having at least one ink-receiving layer provided on at least one surface of a support, wherein the ink-receiving layer contains a cinnamic acid ester derivative.

[0004] Patent Document 3 discloses a toner for developing electrostatic images, which is characterized by containing at least one compound selected from the group consisting of coniferyl alcohol, coniferyl aldehyde, ferulic acid, vanillic acid, and methyl vanillate.

[0005] Patent Document 4 describes a binder resin used in a transparent toner for developing electrostatic images, which contains a polyester resin and a fluorescent brightener, and the fluorescent brightener has a fluorescence peak in the range of 380 nm to 450 nm, and the binder resin has a hue of -0.5 * < 1.0 and -1.0 * <0.5 is disclosed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-247773 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-202938 [Patent Document 3] Japanese Patent Application Publication No. 2017-173509​​ [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-47998 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to provide a toner for developing electrostatic images that is superior in suppressing discoloration in the resulting images compared to toner particles that do not contain a ferulic acid ester compound. [Means for solving the problem]

[0008] Specific means for solving the above problems include the following aspects. <1> A toner for developing electrostatic images, comprising toner particles containing a binder resin, a colorant, and a ferulic acid ester compound. <2> The ferulic acid ester compound contains at least one selected from the group consisting of γ-oryzanols and ferulic acid alkyl ester compounds. <1> 2. The toner for developing electrostatic images according to claim 1. <3> The ferulic acid ester compound contains γ-oryzanol <1> or <2> 2. The toner for developing electrostatic images according to claim 1. <4> The content of the ferulic acid ester compound is 0.01% by mass or more and 20% by mass or less with respect to the total mass of the toner particles. <1> ~ <3> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <5> The ferulic acid ester compound includes a ferulic acid ester compound having a melting point of 150°C or higher and 185°C or lower. <1> ~ <4> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <6> The binder resin contains a crystalline resin. <1> ~ <5> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <7> The crystalline resin includes a crystalline polyester resin. <6> 2. The toner for developing electrostatic images according to claim 1. <8> <1> ~ <7> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9. <9> <1> ~ <7> 10. A toner cartridge containing the toner for developing electrostatic images according to any one of claims 1 to 9, which is detachably mounted on an image forming apparatus. <10> <8> and a developing means for developing an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image, the process cartridge being detachably mountable to an image forming apparatus. <11> an image carrier; a charging means for charging the surface of the image carrier; and an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; <8> and developing means for developing an electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer; transferring means for transferring the toner image formed on the surface of the image carrier to a surface of a recording medium; and fixing means for fixing the toner image transferred to the surface of the recording medium. <12> a charging step of charging the surface of an image carrier; and an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier. <8> a developing step of developing an electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer described in claim 1; a transferring step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium. [Effects of the Invention]

[0009] <1> or <2> According to the invention, there is provided a toner for developing electrostatic images which is superior in suppressing discoloration in the resulting image compared to toner particles which do not contain a ferulic acid ester compound. <3> According to the invention, there is provided a toner for developing electrostatic images which is superior in suppressing discoloration in the resulting image compared to when the ferulic acid ester compound is a ferulic acid alkyl ester. <4> According to the invention, there is provided a toner for developing electrostatic images which has excellent low-temperature fixability in the resulting images, compared to when the content of the ferulic acid ester compound is more than 20% by mass relative to the total mass of the toner particles. <5> According to the invention, there is provided a toner for developing electrostatic images, which has excellent heat storage properties for the resulting images, compared to when the ferulic acid ester compound contains only ferulic acid ester compounds having a melting point of less than 150°C. <6> According to the invention, there is provided a toner for developing electrostatic images which has excellent low-temperature fixing properties compared to when the binder resin is an amorphous resin alone. <7> According to the invention, there is provided a toner for developing electrostatic images which has superior heat storage stability compared to a case where the crystalline resin is a crystalline styrene-acrylic resin alone. <8> , <9> , <10> , <11> or <12> According to the invention, there is provided an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method, which has excellent discoloration suppression properties in the resulting image compared to when the toner for developing an electrostatic image contains toner particles that do not contain a ferulic acid ester compound. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a process cartridge according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0023] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0012] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0013] In the present disclosure, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0014] When embodiments of the present disclosure are described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0015] In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the composition may contain multiple types of particles corresponding to each component. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0016] In the present disclosure, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate.

[0017] In this disclosure, "toner for developing electrostatic images" is also referred to as "toner," "electrostatic image developer" is also referred to as "developer," and "carrier for developing electrostatic images" is also referred to as "carrier."

[0018] (Toner for developing electrostatic images) The electrostatic image developing toner according to this embodiment has toner particles containing a binder resin, a colorant, and a ferulic acid ester compound.

[0019] Digital printing is expanding beyond paper into other areas, most notably textiles. Silkscreen printing is the most common method of printing on textiles, and is still used today for mass printing of apparel, banners, flags, and other items. Meanwhile, in the apparel industry, including fast fashion, small-lot, multi-product production is becoming more common, and digital printing has become the standard for printing on T-shirts, tote bags, and other items. In images obtained using conventional toners for developing electrostatic images, heating during transfer to fabrics and the like can cause components in the toner to react with oxygen in the air to form peroxides, which then react with the binder resin and cause discoloration, particularly yellowing. Furthermore, yellowed images have the problem that the discoloration is accelerated by sunlight, etc., because yellow coloring absorbs short wavelengths and therefore is more likely to absorb wavelengths in the ultraviolet region. In the toner for developing electrostatic images according to this embodiment, by having toner particles containing a ferulic acid ester compound, the oxygen and the peroxide are captured by the ferulic acid ester compound, suppressing discoloration of the image, and since the ferulic acid ester compound also functions as an ultraviolet absorber, it is presumed that the resulting image has excellent discoloration suppression properties.

[0020] The configuration of the toner for developing electrostatic images according to this embodiment will be described in detail below.

[0021] [Toner particles] The toner particles contain a binder resin, a colorant, and a ferulic acid ester compound, and may also contain a release agent and other additives as needed.

[0022] <Ferulic acid ester compound> The toner particles include a ferulic acid ester compound. Ferulic acid ester compounds are ester compounds of ferulic acid (3-(4-hydroxy-3-methoxyphenyl)propenoic acid), and examples thereof include γ-oryzanols, ferulic acid alkyl ester compounds, and ferulic acid aryl ester compounds. Among these, from the viewpoint of inhibiting discoloration in the resulting image (hereinafter also simply referred to as "discoloration inhibition"), it is preferable that the ferulic acid ester compound contains at least one selected from the group consisting of γ-oryzanols and ferulic acid alkyl ester compounds, and it is more preferable that the ferulic acid ester compound contains γ-oryzanols. Furthermore, from the viewpoint of inhibiting discoloration, the ferulic acid ester compound preferably has an aliphatic cyclic structure, more preferably an aliphatic hydrocarbon cyclic structure.

[0023] In this embodiment, γ-oryzanol refers to an ester compound in which a sterol is ester-bonded to ferulic acid. γ-oryzanol is a component unique to rice bran oil and rice germ oil; for example, commercially available rice bran oil contains 0.2 to 0.5% by mass of γ-oryzanol. For example, γ-oryzanol can be extracted and purified from rice bran oil or rice germ oil. For example, it can be extracted and purified from the seed coat (husk) of rice (Oryza sativa Linne), a member of the grass family. Therefore, naturally occurring γ-oryzanol is not a single substance but a mixture of ester compounds in which several sterols are ester-linked to ferulic acid. Furthermore, γ-oryzanols refer to the entire range of ferulic acid ester compounds contained in γ-oryzanol.

[0024] The sterol bound to ferulic acid is not particularly limited, but is preferably a phytosterol. Known sterols bound to ferulic acid in naturally occurring γ-oryzanol include sterols having 25 to 35 carbon atoms (preferably 27 to 33 carbon atoms), such as cycloartenol (30 carbon atoms (also referred to as "carbon atom number")), 24-methylenecycloartanol (31 carbon atoms), campesterol (28 carbon atoms), β-sitosterol (29 carbon atoms), and cyclobutanol (31 carbon atoms).

[0025] Examples of γ-oryzanol include cycloartenol ferulate, 24-methylenecycloartanol ferulate, campesterol ferulate, β-sitosterol ferulate, cyclobulanol ferulate, etc. Commercially available γ-oryzanol includes a mixture of cycloartenol ferulate, 24-methylenecycloartanol ferulate, campesterol ferulate, β-sitosterol ferulate, and cyclobulanol ferulate. Among these, from the viewpoint of inhibiting discoloration, the ferulic acid ester compound preferably contains cycloartenol ferulic acid ester as γ-oryzanol, more preferably contains 50% by mass or more of cycloartenol ferulic acid ester relative to the total γ-oryzanol content, and particularly preferably contains 80% by mass or more of cycloartenol ferulic acid ester relative to the total γ-oryzanol content.

[0026] In the ferulic acid alkyl ester compound, the number of carbon atoms in the alkyl group in the alkyl ester moiety is preferably 1 to 24, more preferably 2 to 16, and particularly preferably 6 to 10, from the viewpoint of inhibiting discoloration. The alkyl group in the alkyl ester portion of the ferulic acid alkyl ester compound may be a linear alkyl group, a branched alkyl group, or an alkyl group having a ring structure, but from the viewpoints of discoloration suppression and low-temperature fixability, a branched alkyl group is preferred. Examples of ferulate alkyl ester compounds include methyl ferulate, ethyl ferulate, n-propyl ferulate, isopropyl ferulate, n-butyl ferulate, s-butyl ferulate, isobutyl ferulate, t-butyl ferulate, n-pentyl ferulate, n-hexyl ferulate, cyclohexyl ferulate, n-heptyl ferulate, n-octyl ferulate, 2-ethylhexyl ferulate, n-nonyl ferulate, n-decyl ferulate, n-dodecyl ferulate, and n-docosyl ferulate. Among these, 2-ethylhexyl ferulate is preferred from the viewpoint of discoloration suppression and low-temperature fixability.

[0027] Ferulic acid ester compounds also include ferulic acid acyl-β-D-glucoside.

[0028] Furthermore, from the viewpoint of thermal storage stability, the ferulic acid ester compound preferably includes a ferulic acid ester compound having a melting point of 55°C or higher, more preferably a ferulic acid ester compound having a melting point of 120°C or higher, even more preferably a ferulic acid ester compound having a melting point of 150°C or higher and 185°C or lower, and particularly preferably a ferulic acid ester compound having a melting point of 150°C or higher and 185°C or lower. The melting point of the ferulic acid ester compound is measured in the same manner as the melting temperature of a crystalline resin, which will be described later. That is, it is determined from a DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" as described in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0029] The ferulic acid ester compound may be contained alone or in combination of two or more. From the viewpoints of discoloration suppression, low-temperature fixability, and thermal storage stability, the content of the ferulic acid ester compound is preferably 0.01% by mass or more and 120% by mass or less, more preferably 0.02% by mass or more and 15% by mass or less, even more preferably 0.1% by mass or more and 8% by mass or less, and particularly preferably 1% by mass or more and 5% by mass or less, relative to the total mass of the toner particles.

[0030] <Binder resin> Examples of binder resins include homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), and vinyl resins made of copolymers of two or more of these monomers. Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binder resins may be used alone or in combination of two or more.

[0031] As the binder resin, a polyester resin is preferable. Examples of polyester resins include known amorphous polyester resins. The polyester resin may be used in combination with a crystalline polyester resin. However, the content of the crystalline polyester resin is preferably in the range of 2% by mass to 40% by mass (preferably 5% by mass to 25% by mass) relative to the total binder resin. From the viewpoint of low-temperature fixability and heat storage stability, the binder resin preferably contains a crystalline resin, and more preferably contains a crystalline polyester resin.

[0032] The "crystalline" nature of a resin refers to the presence of a clear endothermic peak rather than a stepwise change in endothermic heat in differential scanning calorimetry (DSC). Specifically, this refers to the half-width of the endothermic peak being within 10°C when measured at a heating rate of 10°C / min. On the other hand, the term "amorphous" for a resin means that the half-width exceeds 10°C, that the endothermic amount exhibits a stepwise change, or that no clear endothermic peak is observed.

[0033] Amorphous polyester resin Examples of the amorphous polyester resin include a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. Note that, as the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0034] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acids may be used alone or in combination of two or more.

[0035] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, preferred polyhydric alcohols are aromatic diols and alicyclic diols, and more preferred are aromatic diols. As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0036] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0037] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurements by GPC are performed using a Tosoh Corporation GPC HLC-8120GPC measuring instrument and a Tosoh Corporation TSKgel SuperHM-M (15 cm) column in tetrahydrofuran (THF) as a solvent. The weight-average molecular weight and number-average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0038] The amorphous polyester resin can be obtained by a known manufacturing method, for example, by carrying out the reaction at a polymerization temperature of 180°C or higher and 230°C or lower, reducing the pressure in the reaction system as necessary, and removing water and alcohol generated during the condensation. If the raw material monomer is not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present, it is advisable to first condense the poorly compatible monomer with the acid or alcohol to be polycondensed, and then polycondense the monomer with the main component.

[0039] Crystalline polyester resin The crystalline polyester resin may be, for example, a polycondensate of a polycarboxylic acid and a polyhydric alcohol. Note that, as the crystalline polyester resin, a commercially available product or a synthesized product may be used. Here, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group, since it easily forms a crystalline structure.

[0040] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acid may be a tricarboxylic or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the tricarboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2 , 4-naphthalenetricarboxylic acid, etc.), anhydrides thereof, or lower alkyl esters thereof (for example, having 1 to 5 carbon atoms). As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polycarboxylic acids may be used alone or in combination of two or more.

[0041] Examples of polyhydric alcohols include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). 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 1,14-eicosanedecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. The polyhydric alcohol may be a trihydric or higher alcohol having a crosslinked or branched structure, such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol, in combination with the diol. The polyhydric alcohols may be used alone or in combination of two or more.

[0042] Here, the polyhydric alcohol has an aliphatic diol content of 80 mol % or more, preferably 90 mol % or more.

[0043] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121-1987 "Method for measuring transition temperatures of plastics."

[0044] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0045] The crystalline polyester resin can be obtained by a known manufacturing method, for example, in the same manner as the amorphous polyester.

[0046] The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, based on the total mass of the toner particles.

[0047] <Coloring agent> Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and the like. Examples of the dye include various pigments such as phosphorus blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and various dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0048] The colorant may be surface-treated as needed, or may be used in combination with a dispersant. Furthermore, a plurality of colorants may be used in combination.

[0049] The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0050] <Release agent> Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto.

[0051] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" as described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0052] The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0053] <Other additives> Examples of other additives include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0054] <Characteristics of toner particles> The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) that coats the core part.

[0055] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0056] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

[0057] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0058] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, this value is measured by the following method. First, the toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantaneously activating a strobe light, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).The number of samples to be sampled when calculating the average circularity is 3,500. When the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0059] [External additives] Examples of external additives include inorganic particles, such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0060] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles.

[0061] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0062] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles.

[0063] [Method for producing toner for developing electrostatic images] The toner for developing electrostatic images according to this exemplary embodiment can be obtained by producing toner particles and then externally adding an external additive to the toner particles.

[0064] The toner particles may be produced by any of a dry production method (for example, a kneading and pulverization method) and a wet production method (for example, an aggregation and coalescence method, a suspension polymerization method, a dissolution and suspension method). There are no particular limitations on these production methods, and any known production method may be used. Among these, it is preferable to obtain toner particles by the aggregation and coalescence method.

[0065] When the toner particles are produced by the aggregation and coalescence method, the following production method is preferred. a step of preparing a resin particle dispersion in which resin particles containing a binder resin and a ferulic acid ester compound are dispersed (a resin particle dispersion preparation step); a step of preparing a colorant dispersion in which a colorant is dispersed (colorant dispersion preparation step); a step of aggregating the mixed particles in a mixed dispersion obtained by mixing a resin particle dispersion and a colorant dispersion (in a dispersion after mixing other particle dispersions as necessary) to form aggregated particles (aggregated particle forming step); a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles (fusion and coalescence step).

[0066] Each step will be described in detail below.

[0067] -Resin particle dispersion preparation process- The resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0068] Examples of the dispersion medium used in the resin particle dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water, alcohols, etc. These may be used alone or in combination of two or more.

[0069] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0070] In a resin particle dispersion, resin particles can be dispersed in a dispersion medium by common dispersion methods such as a rotary shear homogenizer, a ball mill with media, a sand mill, or a Dynomill. Depending on the type of resin particles, the resin particles may be dispersed in a dispersion medium by a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, neutralizing the organic continuous phase (O phase) by adding a base, and then introducing an aqueous medium (W phase) to invert the phase from W / O to O / W, thereby dispersing the resin in particulate form in the aqueous medium. In addition, as a method for granulating a resin in the absence of an organic solvent, a method of melting the resin at high temperature and dispersing it in water as particles can be mentioned.For example, in the absence of an organic solvent, a method of melt-mixing the resin, adding a surfactant to the resin as needed, and adding a basic agent and water to the resin to form an emulsion of resin particles can be mentioned.In addition, a ferulic acid ester compound can be mixed with the molten resin. Furthermore, when preparing a resin particle dispersion containing a ferulic acid ester compound, it is preferable to prepare the dispersion by dissolving the resin to be dispersed and the ferulic acid ester compound in a hydrophobic organic solvent using a phase inversion emulsification method.

[0071] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm to 1 μm, more preferably 0.08 μm to 0.8 μm, and even more preferably 0.1 μm to 0.6 μm. The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., HORIBA LA-700), and the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the smallest particle size side, and the particle size at which the cumulative 50% of all particles is determined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same way.

[0072] The content of resin particles contained in the resin particle dispersion is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0073] In addition, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the binder resin particle dispersion. That is, the volume average particle diameter, dispersion medium, dispersion method, and particle content of the particles in the binder resin particle dispersion are the same as those of the colorant particles dispersed in the colorant particle dispersion. The same applies to the release agent particles dispersed in the release agent particle dispersion liquid.

[0074] -Agglomerated particle formation process- A resin particle dispersion, a fluorescent organic pigment dispersion, a non-fluorescent organic pigment dispersion, and a release agent particle dispersion are mixed together, and in the mixed dispersion, the resin particles, the fluorescent organic pigment, the non-fluorescent organic pigment, and the release agent particles are hetero-aggregated to form aggregated particles containing the resin particles, the fluorescent organic pigment, the non-fluorescent organic pigment, and the release agent particles, and having a diameter close to that of the target toner particles.

[0075] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 or higher and 5 or lower), and a dispersion stabilizer is added as necessary.Then, the mixed dispersion is heated to a temperature close to the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles minus 30°C or higher and the glass transition temperature minus 10°C or lower), causing the particles dispersed in the mixed dispersion to aggregate and form aggregated particles. In the aggregate particle formation step, for example, the mixed dispersion may be stirred with a rotary shear homogenizer, an aggregating agent may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), a dispersion stabilizer may be added as needed, and then the mixture may be heated.

[0076] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. When a metal complex is used as the flocculant, the amount of surfactant used can be reduced, and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used together with the flocculant, and a chelating agent is preferably used as this additive.

[0077] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), or aminocarboxylic acid (e.g., iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), or ethylenediaminetetraacetic acid (EDTA). The amount of the chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of the resin particles.

[0078] -Fusion / unification process- Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10°C to 30°C higher than the glass transition temperature of the resin particles) to fuse and coalesce the aggregated particles, thereby forming toner particles.

[0079] Through the above steps, toner particles are obtained. After obtaining an aggregated particle dispersion in which aggregated particles are dispersed, the toner particles may be produced through the following steps: a step of further mixing the aggregated particle dispersion with a resin particle dispersion in which resin particles are dispersed, and aggregating the aggregated particles so that further resin particles adhere to the surfaces of the aggregated particles to form second aggregated particles; and a step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed, and fusing and coalescing the second aggregated particles to form toner particles having a core-shell structure.

[0080] After the fusion and coalescence process is completed, the toner particles in the dispersion are subjected to a known washing process, solid-liquid separation process, and drying process to obtain dried toner particles. In the washing process, from the viewpoint of chargeability, it is preferable to perform sufficient substitution washing with ion-exchanged water. In the solid-liquid separation process, from the viewpoint of productivity, it is preferable to perform suction filtration, pressure filtration, etc. In the drying process, from the viewpoint of productivity, it is preferable to perform freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0081] The toner according to this embodiment is produced by, for example, adding an external additive to the obtained dry toner particles and mixing them. The mixing can be carried out using, for example, a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, etc.

[0082] (Electrostatic image developer) The electrostatic image developer according to this embodiment contains at least the electrostatic image developing toner according to this embodiment. The electrostatic image developer according to the present embodiment may be a one-component developer containing only the toner for developing electrostatic images according to the present embodiment, or may be a two-component developer containing a mixture of the toner for developing electrostatic images and a carrier.

[0083] The carrier is not particularly limited, and known carriers can be used, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a resin, magnetic powder dispersion carriers in which magnetic powder is dispersed in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and the surface of the core material is coated with a resin.

[0084] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0085] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resins containing organosiloxane bonds or modified products thereof, fluororesin, polyester, polycarbonate, phenolic resin, and epoxy resin. The coating resin and matrix resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0086] To coat the surface of the core material with a resin, a method of coating with a coating layer-forming solution prepared by dissolving the coating resin and various additives (used as needed) in an appropriate solvent can be used. The solvent is not particularly limited and may be selected taking into consideration the type of resin used, its suitability for application, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer; a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material; a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air; and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and then the solvent is removed.

[0087] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0088] (Image forming device, image forming method) An image forming apparatus and an image forming method according to this embodiment will be described. The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, a developing unit that contains an electrostatic image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer, a transfer unit that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing unit that fixes the toner image transferred to the surface of the recording medium. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0089] The image forming apparatus according to this embodiment carries out an image forming method (the image forming method according to this embodiment) that includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0090] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; an intermediate transfer type apparatus that primarily transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer medium, and then secondarily transfers the toner image transferred to the surface of the intermediate transfer medium to the surface of a recording medium; an apparatus equipped with a cleaning means that cleans the surface of the image carrier after the transfer of the toner image but before charging; and an apparatus equipped with a discharging means that irradiates the surface of the image carrier with discharging light to discharge it after the transfer of the toner image but before charging. When the image forming apparatus according to the present embodiment is an apparatus of the intermediate transfer type, the transfer means is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means for primarily transferring the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means for secondarily transferring the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0091] In the image forming apparatus according to the present embodiment, for example, the portion including the developing means may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with developing means that accommodates the electrostatic image developer according to the present embodiment is suitably used.

[0092] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0093] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 includes first through fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images in the colors yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side horizontally spaced a predetermined distance apart from one another. Note that these units 10Y, 10M, 10C, and 10K may also be process cartridges that are detachable from the image forming apparatus.

[0094] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 serving as an intermediate transfer body extends through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a support roll 24 that are spaced apart from each other and arranged from left to right in the drawing, and is configured to run in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 in a direction away from the drive roll 22 by a spring or the like (not shown), thereby applying tension to the intermediate transfer belt 20 wound around them. In addition, an intermediate transfer body cleaning device 30 is provided on the image carrier side of the intermediate transfer belt 20, facing the drive roll 22. In addition, the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with toner including four colors of toner, yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0095] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y, which forms a yellow image and is disposed upstream in the direction of travel of the intermediate transfer belt, will be described here as a representative. Note that parts equivalent to those of the first unit 10Y are given reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y), and descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0096] The first unit 10Y has a photoreceptor 1Y that acts as an image carrier. Around the photoreceptor 1Y, there are a charging roll (an example of a charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it, a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. A cleaning device (an example of a cleaning device) 6Y is arranged in this order. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is positioned opposite the photoreceptor 1Y. Furthermore, a bias power supply (not shown) that applies a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0097] The operation of forming a yellow image in first unit 10Y will be described below. First, prior to operation, the surface of the photosensitive member 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has conductivity (for example, volume resistivity at 20°C: 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistivity of Ωcm or less. This photosensitive layer normally has a high resistance (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the irradiated portion changes. Therefore, a laser beam 3Y is output to the charged surface of the photosensitive element 1Y via an exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photosensitive element 1Y, thereby forming an electrostatic charge image of a yellow image pattern on the surface of the photosensitive element 1Y.

[0098] An electrostatic image is an image formed on the surface of the photosensitive element 1Y by charging it; the laser beam 3Y reduces the resistivity of the irradiated portion of the photosensitive layer, causing the charged charges on the surface of the photosensitive element 1Y to flow, while the charges remain in the portions not irradiated by the laser beam 3Y, forming a so-called negative latent image. The electrostatic image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0099] The developing device 4Y contains an electrostatic image developer containing, for example, at least yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. The photoreceptor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0100] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y to the primary transfer roll 5Y acts on the toner image, causing the toner image on the photoreceptor 1Y to be transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the (-) polarity of the toner, and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

[0101] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit 10M and subsequent units is also controlled in accordance with the first unit. In this way, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed sequentially through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and transferred.

[0102] Intermediate transfer belt 2 onto which four color toner images are transferred through the first to fourth units. The image transfer belt 20 then reaches a secondary transfer section made up of an intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 arranged on the image bearing surface side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a negative polarity, the same as the negative polarity of the toner, and an electrostatic force directed from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0103] Thereafter, the recording paper P is sent to the pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0104] Examples of the recording paper P onto which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, examples of the recording medium include overhead projector sheets and the like. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of plain paper is coated with resin or the like, or art paper for printing, etc., is preferably used.

[0105] The recording paper P on which the color image has been fixed is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0106] <Process cartridges / toner cartridges> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that is detachably attached to an image forming apparatus and that contains the electrostatic image developer according to this embodiment and is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image.

[0107] The process cartridge according to this embodiment is not limited to the above configuration, but may also be configured to include a developing device and, if necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0108] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0109] FIG. 2 is a schematic diagram showing the configuration of the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured to integrally combine and hold a photosensitive member 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photosensitive member 107, a developing device 111 (an example of a developing means), and a photosensitive member cleaning device 113 (an example of a cleaning means), which are held by a housing 117 provided with, for example, mounting rails 116 and an opening 118 for exposure, and is made into a cartridge. In FIG. 2, 109 denotes an exposure device (an example of an electrostatic image forming means), 112 denotes a transfer device (an example of a transfer means), 115 denotes a fixing device (an example of a fixing means), and 300 denotes recording paper (an example of a recording medium).

[0110] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment contains the toner according to the present embodiment and is used for image formation. The toner cartridge is a detachable toner cartridge that contains replenishment toner to be supplied to a developing unit provided in an image forming apparatus.

[0111] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing device (color) by toner supply pipes (not shown). When the toner stored in a toner cartridge runs low, the toner cartridge is replaced. [Example]

[0112] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are by mass. All syntheses, processing, preparations, etc. were carried out at room temperature (25°C ± 3°C) unless otherwise noted.

[0113] Example 1 <Preparation of amorphous polyester resin> Terephthalic acid: 30 parts by mole Fumaric acid: 70 parts by mole Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole The above materials were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 220°C over 1 hour. Then, 1 part of titanium tetraethoxide was added for every 100 parts of the above materials. The temperature was raised to 230°C over 30 minutes while distilling off the resulting water. The dehydration condensation reaction was continued at this temperature for 1 hour, and the reaction mixture was then cooled. This resulted in an amorphous polyester resin with a weight-average molecular weight of 18,000 and a glass transition temperature of 60°C.

[0114] <Preparation of Amorphous Polyester Resin Particle Dispersion (1)> Amorphous polyester resin: 200 parts by weight Methyl ethyl ketone: 100 parts by weight Isopropyl alcohol: 70 parts by weight γ-oryzanol (γ-oryzanol (containing 98% by mass of cycloartenyl ferulate), melting point 160°C, manufactured by Oryza Oil & Fat Chemical Co., Ltd.): 7.5 parts by mass The above components were placed in a jacketed 3-liter reaction vessel (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dropping device, and anchor blades, and the resin was dissolved by stirring and mixing at 100 rpm (revolutions per minute) while maintaining the temperature at 70°C in a water-circulating thermostatic bath. The stirring speed was then increased to 150 rpm, the water-circulating thermostatic bath was set to 66°C, and 10 parts by mass of 10% by mass aqueous ammonia (reagent) was added over 10 minutes. After that, a total of 600 parts by mass of ion-exchanged water maintained at 66°C was added dropwise at a rate of 5 parts by mass / min to induce phase inversion, yielding an emulsion. 600 parts of the resulting emulsion and 525 parts by mass of ion-exchanged water were placed in an eggplant flask and placed in an evaporator (manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. While rotating the eggplant flask, the pressure was increased to 60°C in a hot water bath, and the pressure was reduced to 7 kPa while taking care to prevent bumping, to remove the solvent. When the amount of recovered solvent reached 825 parts by mass, the pressure was returned to normal, and the eggplant flask was cooled with water to obtain a dispersion containing resin particles with a volume average particle size of 163 nm. Ion-exchanged water was added to obtain a ferulic acid ester-containing amorphous polyester resin particle dispersion (1) with a solids concentration of 20% by mass.

[0115] <Preparation of Colorant Particle Dispersion (1)> Cyan pigment (Pigment Blue 15:3, manufactured by Dainichi Seika Color & Chemicals Mfg. Co., Ltd.): 10 parts Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 80 parts The above materials were mixed and dispersed for 1 hour using a high-pressure impact disperser (Ultimizer HJP30006, Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion (1) with a volume average particle size of 180 nm and a solid content of 20%.

[0116] <Preparation of Release Agent Particle Dispersion (1)> Paraffin wax (HNP-9, manufactured by Nippon Seiro Co., Ltd.): 50 parts Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 200 parts The above materials were heated to 120°C and thoroughly dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA), and then dispersed using a pressure discharge homogenizer. When the volume average particle size reached 200 nm, the particles were collected to obtain a release agent particle dispersion (1) with a solid content of 20%.

[0117] <Preparation of Toner (1)> Amorphous polyester resin particle dispersion (1): 200 parts Colorant particle dispersion (1): 20 parts Release agent particle dispersion (1): 30 parts Polyaluminum chloride: 0.4 parts Ion-exchanged water: 100 parts The above materials were placed in a round stainless steel flask and thoroughly mixed and dispersed using a homogenizer (Ultra Turrax T50, IKA). The flask was then heated to 48°C in a heating oil bath while stirring. The reaction system was maintained at 48°C for 60 minutes, and 70 parts of amorphous polyester resin particle dispersion (1) was slowly added. The pH was then adjusted to 8.0 using a 0.5 mol / L aqueous sodium hydroxide solution. The flask was sealed, the stirring shaft was magnetically sealed, and the mixture was heated to 90°C with continued stirring and maintained for 30 minutes. The mixture was then cooled at a rate of 5°C / min, solid-liquid separated, and thoroughly washed with ion-exchanged water. The solid-liquid separated product was then redispersed in ion-exchanged water at 30°C and washed with stirring at a rotation speed of 300 rpm (revolutions per minute) for 15 minutes. This washing operation was repeated six more times, and when the pH of the filtrate reached 7.54 and the electrical conductivity reached 6.5 μS / cm, solid-liquid separation was performed, followed by vacuum drying for 24 hours to obtain toner particles with a volume average particle size of 5.7 μm.

[0118] 100 parts of the above toner particles and 2.5 parts of silica particles (surface hydrophobized with hexamethyldisilazane, average primary particle size 40 nm) were mixed in a Henschel mixer to obtain toner (1) (toner for developing electrostatic images of Example 1).

[0119] <Preparation of Carrier 1> Ferrite particles (average particle size 35 μm): 100 parts Toluene: 14 parts Polymethyl methacrylate (MMA, weight average molecular weight 75,000): 5 parts Carbon black: 0.2 parts (VXC-72, manufactured by Cabot Corporation, volume resistivity: 100 Ω cm or less) The above materials except for the ferrite particles were dispersed in a sand mill to prepare a dispersion liquid, and this dispersion liquid was placed in a vacuum degassing kneader together with the ferrite particles, and dried under reduced pressure while stirring to obtain Carrier 1.

[0120] <Preparation of Electrostatic Image Developer> 100 parts of the obtained carrier 1 and 6 parts of the toner (1) were charged into a V blender and stirred for 20 minutes, and then sieved through a sieve with 212 μm openings to obtain an electrostatic image developer of Example 1.

[0121] Example 2 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that γ-oryzanol was replaced with ferulate acyl-β-D-glucoside (melting point 125°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0122] Example 3 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that γ-oryzanol was changed to docosyl ferulate (melting point 58°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0123] Example 4 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that γ-oryzanol was changed to 2-ethylhexyl ferulate (liquid at 25° C.).

[0124] (Examples 5 to 8) An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the amount of γ-oryzanol used in preparing amorphous polyester resin particle dispersion (1) was adjusted to the contents shown in Table 1.

[0125] Example 9 Amorphous polyester resin particle dispersion (2) was prepared in the same manner as in Example 1, except that the amount of γ-oryzanol used in preparing amorphous polyester resin particle dispersion (1) was adjusted to the contents shown in Table 1.

[0126] <Preparation of Crystalline Polyester Resin Particle Dispersion> Decanedioic acid (Tokyo Chemical Industry Co., Ltd.): 81 parts Hexanediol (Fujifilm Wako Pure Chemical Industries, Ltd.): 47 parts The above materials were charged into a flask, and the temperature was raised to 160°C over 1 hour. After confirming that the reaction system was uniformly stirred, 0.03 parts of dibutyltin oxide was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. The reaction liquid was then cooled, solid-liquid separation was performed, and the solid was dried at 40°C under reduced pressure to obtain a crystalline polyester resin (melting point 64°C, weight average molecular weight 15,000).

[0127] Crystalline polyester resin: 50 parts Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts Ion-exchanged water: 200 parts The above materials were heated to 120°C and thoroughly dispersed using a homogenizer (Ultra Turrax T50, IKA), and then dispersed using a pressure discharge homogenizer. When the volume average particle size reached 180 nm, the particles were collected to obtain a crystalline polyester resin particle dispersion with a solid content of 20%.

[0128] <Preparation of Toner (9)> Amorphous polyester resin particle dispersion (2): 150 parts Crystalline polyester resin particle dispersion: 50 parts Colorant particle dispersion (1): 20 parts Release agent particle dispersion (1): 30 parts Polyaluminum chloride: 0.4 parts Ion-exchanged water: 100 parts The above materials were placed in a round stainless steel flask and thoroughly mixed and dispersed using a homogenizer (Ultra Turrax T50, IKA). The flask was then heated to 48°C in a heating oil bath while stirring. The reaction system was maintained at 48°C for 60 minutes, and 70 parts of amorphous polyester resin particle dispersion (2) was slowly added. The pH was then adjusted to 8.0 using a 0.5 mol / L aqueous sodium hydroxide solution. The flask was sealed, the stirring shaft was magnetically sealed, and the mixture was heated to 90°C with continued stirring and maintained for 30 minutes. The mixture was then cooled at a rate of 5°C / min, solid-liquid separated, and thoroughly washed with ion-exchanged water. The solid-liquid separated product was then redispersed in ion-exchanged water at 30°C and washed with stirring at a rotation speed of 300 rpm (revolutions per minute) for 15 minutes. This washing operation was repeated six more times, and when the pH of the filtrate reached 7.54 and the electrical conductivity reached 6.5 μS / cm, solid-liquid separation was performed, followed by vacuum drying for 24 hours to obtain toner particles with a volume average particle size of 5.7 μm.

[0129] 100 parts of the above toner particles and 2.5 parts of silica particles (surface hydrophobized with hexamethyldisilazane, average primary particle size 40 nm) were mixed in a Henschel mixer to obtain toner (9) (toner for developing electrostatic images of Example 9).

[0130] <Preparation of Electrostatic Image Developer> 100 parts of Carrier 1 and 6 parts of Toner (9) were charged into a V-blender and stirred for 20 minutes, and then sieved through a sieve with 212 μm openings to obtain an electrostatic image developer of Example 9.

[0131] Example 10 A toner and an electrostatic image developer were prepared and evaluated in the same manner as in Example 1, except that the amorphous polyester resin particle dispersion (1) was changed to the following styrene acrylic resin particle dispersion (1).

[0132] <Preparation of styrene acrylic resin particle dispersion (1)> -Oil phase materials- Styrene (Fujifilm Wako Pure Chemical Industries, Ltd.): 30 parts n-Butyl acrylate (Fujifilm Wako Pure Chemical Industries, Ltd.): 10 parts β-Carboxyethyl acrylate (Rhodia Nikka): 1.3 parts Dodecanethiol (Fujifilm Wako Pure Chemical Industries, Ltd.): 0.4 parts

[0133] -Ingredients for aqueous phase 1- Ion-exchanged water: 17 parts Anionic surfactant: Dowfax (Dow Chemical Company): 0.4 parts

[0134] -Ingredients for aqueous phase 2- Ion-exchanged water: 40 parts Anionic surfactant: Dowfax (Dow Chemical Company): 0.05 parts Ammonium peroxodisulfate (Fujifilm Wako Pure Chemical Industries, Ltd.): 0.4 parts

[0135] The oil phase materials and aqueous phase 1 materials were mixed and stirred separately, and the two were mixed to form an emulsion dispersion of the monomer. Separately, the aqueous phase 2 materials were added to a reaction vessel, the atmosphere in the reaction vessel was thoroughly purged with nitrogen, and the reaction system was heated in an oil bath with stirring until the temperature reached 75°C. The emulsion dispersion of the monomer was gradually added dropwise to the reaction vessel over 3 hours to carry out emulsion polymerization. After the addition was completed, the polymerization was continued at 75°C and terminated after 3 hours, yielding a styrene-acrylic resin particle dispersion (1) with a solids content of 42% by mass. The volume average particle size was measured using a particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.) and found to be 250 nm. The glass transition temperature of the resin was measured using a differential scanning calorimeter (DSC-50, manufactured by Shimadzu Corporation) at a heating rate of 10°C / min and found to be 52°C. The number average molecular weight (polystyrene equivalent) was measured using GPC and found to be 13,000.

[0136] (Comparative Example 1) An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that γ-oryzanol was not used in preparing the amorphous polyester resin particle dispersion.

[0137] (Comparative Example 2) <Preparation of amorphous polyester resin dispersion containing fluorescent whitening agent particles> -Melting process- Amorphous polyester resin (glass transition temperature (Tg): 60°C): 200 parts by weight 25% by weight sodium hydroxide solution: 0.4 parts by weight Fluorescent whitening agent (Tinopal OB (substance name: 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole)), manufactured by BASF Japan Ltd.): 7.5 parts by mass The above components were fed into the raw material inlet of a twin-screw extruder (trade name: TEM26SS, manufactured by Toshiba Machine Co., Ltd.), and 4.1 parts by mass of a 48.5% by mass aqueous solution of sodium dodecyl diphenyl ether disulfonate (manufactured by Sanyo Chemical Industries, Ltd., Eleminol MON-7) was fed as a surfactant into the fourth barrel of the twin-screw extruder. The mixture was melted at a barrel temperature of 90°C and a screw rotation speed of 400 rpm (revolutions per minute) to produce an oily mixture.

[0138] -Emulsification process (phase inversion emulsification process)- To the fifth barrel of the twin-screw extruder, 150 parts by mass of ion-exchanged water (ion-exchanged water 1) adjusted to 90°C was added, to the seventh barrel, 150 parts by mass of ion-exchanged water (ion-exchanged water 2) adjusted to 90°C was added, and to the ninth barrel, 150 parts by mass of ion-exchanged water (ion-exchanged water 3) adjusted to 90°C was added, and the oily mixture was emulsified to obtain an amorphous polyester resin dispersion containing fluorescent brightener particles. The average feed rate F of the oily mixture at this time was 12 kg / h. The volumetric particle size distribution of the particles in the obtained fluorescent brightener particle-containing amorphous polyester resin dispersion was measured using a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). As a result, the volume average particle size of the resin particles was 0.2 μm. The solid content was 31%.

[0139] An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that an amorphous polyester resin dispersion containing fluorescent brightener particles was used instead of the amorphous polyester resin particle dispersion (1).

[0140] The resulting toner for developing electrostatic images and the electrostatic image developer were used to carry out the following evaluations.

[0141] <Evaluation of discoloration prevention after iron-on printing and lightfastness test> -Iron print test- An Apeos C7070 manufactured by Fujifilm Business Innovation Co., Ltd. was used to form the evaluation image. The resulting developer was placed in the developing unit, and replenishment toner (the same toner as contained in the developer) was placed in the toner cartridge. The image forming apparatus was then used to print at a speed of 70 sheets per minute. The toner coverage was adjusted to 4.0 mg / cm² at a 100% image area ratio on color laser iron-on transfer paper (manufactured by Sanwa Supply Co., Ltd., LBP-TPRCLN), and a 5 cm x 5 cm halftone image with a 70% image area ratio was printed. The image area was cut out, the transfer area backing was peeled off from the printed surface, and the image was attached to cotton fabric (100% cotton, Yuzawaya Shoji Co., Ltd., Color Broadcloth Plain 056 White YBC40205) and placed on an ironing mat (Quick Art Co., Ltd., Rubber Sponge Mat, Medium size). Next, a finishing paper was placed on top and the image was ironed with a dry iron (Panasonic Corporation, Using an iron (NI-A66 manufactured by Ikebukuro Co., Ltd.), the dial was set to high (approximately 180 to 200°C) and pressed against the printer for 20 seconds to create an iron-print image. The image before and after transfer was measured using X-Rite 939 manufactured by X-Rite. * a * b * Measure the color difference ΔE={(ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2} 0.5 The value of ΔL was calculated. * is the L before transcription * - Post-transcription L * represents the value of Δa * is a before transcription * -Post-transcription and * represents the value of Δb * is the b before transcription * -After transcription and b * Represents the value of The evaluation criteria are as follows: The smaller the ΔE value, the better, and A to D are at a level that presents no practical problems. A: ΔE≦1.0 B: 1.0<ΔE≦2 C:2<ΔE≦3 D:3<ΔE≦4 E:4<ΔE≦10

[0142] -Lightfastness test- The light resistance test device used was a SUNTEST CPS+ (manufactured by Atlas). The test was conducted under the specified light irradiation conditions (light source: xenon lamp, filter: quartz coated glass, light intensity (average): the light intensity in the ultraviolet-visible region of 250 nm to 765 nm was approximately 550 W / m 2 The halftone images were irradiated with light for 240 hours, and the L * value, a * value and b * The values ​​were measured and evaluated according to the following criteria. Using X-Rite939 manufactured by X-Rite, * a * b * Measure the color difference ΔE={(ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2} 0.5 The value of ΔL was calculated. * is the transcribed L * -After exposure and L * represents the value of Δa * is a after transcription * -After exposure and * represents the value of Δb * is the transcribed b * -After exposure and b * Represents the value of The evaluation criteria are as follows: The smaller the ΔE value, the better, and A to D are at a level that presents no practical problems. A:ΔE≦3 B:3<ΔE≦5 C:5<ΔE≦10 D:10<ΔE≦15 E:15<ΔE≦25

[0143] <Low temperature fixability evaluation> An Apeos C7070 manufactured by Fujifilm Business Innovation Co., Ltd. was prepared as an image forming apparatus for forming evaluation images. The resulting developer was placed in a developing device, and replenishment toner (the same toner as contained in the developer) was placed in a toner cartridge. Subsequently, the image forming apparatus was used to print images on high-quality paper (manufactured by Fujifilm Business Innovation Co., Ltd., product name J, basis weight 82 g / m) at a fixing temperature of 150°C and a print speed of 70 sheets / min. 2 A 5cm x 5cm solid image with an image area ratio of 100% was printed on a sheet of paper (paper thickness: 97µm). The bending strength of the solid image was evaluated. To evaluate low-temperature fixability, the sheet was folded in half at 25°C with the solid image facing inward, a 300g weight was placed on it, and after one minute the sheet was opened and the folded area was rubbed with gauze. The degree of image damage caused by the rubbing was visually observed, and the image bending strength was evaluated according to the following criteria: G1 to G4 are at a level that is acceptable for practical use. G1: Even when rubbed with gauze, there is almost no image loss, and the folding history can be seen. G2: When rubbed with gauze, only a very thin white line of image loss occurred at the folded area. This level is not a problem for practical use. G3: When rubbed with gauze, the folded area turned into a white streak, resulting in image loss, and cracks also appeared in the surrounding area. G4: When rubbing with gauze, wide white lines appear at the folded part and its surroundings, causing image loss. G5: When rubbed with gauze, the image was lost in areas other than the folded area, and the image was barely fixed.

[0144] <Heat storage stability evaluation> Electrostatic image developing toners were left in a 50°C / 50% RH environment for approximately 24 hours and evaluated for thermal storage stability under the following conditions. The electrostatic image developing toners were left in a 25°C / 50% RH environment for approximately 24 hours and then placed on the 53 μm sieve of a toner powder tester (manufactured by Hosokawa Micron Corporation), which had sieves with 53 μm, 45 μm, and 38 μm openings arranged in series from the top. Vibration was applied at an amplitude of 1 mm for 90 seconds. The mass of the toner on each sieve after vibration was measured, and the weights were multiplied by 0.5, 0.3, and 0.1 from top to bottom. The resulting sum was then divided by the amount of electrostatic image developing toner before measurement and expressed as a percentage. The evaluation criteria are shown below. Note that a small percentage value is preferable for thermal storage stability, and a rating of A to D indicates a practically acceptable level. A: The percentage value is 10% by mass or less. B: The percentage value is greater than 10% by mass and equal to or less than 20% by mass. C: The percentage value is greater than 20% by mass and equal to or less than 30% by mass. D: The percentage value is greater than 30% by mass and equal to or less than 40% by mass. E: The percentage value exceeds 40% by mass.

[0145] The evaluation results are summarized in Table 1.

[0146] [Table 1]

[0147] The content of the ferulic acid ester compound shown in Table 1 indicates the amount relative to the total mass of the toner particles.

[0148] As shown in Table 1, the electrostatic image developing toners of Examples 1 to 10 were superior to the electrostatic image developing toners of Comparative Examples 1 and 2 in terms of suppressing discoloration in the resulting images.

[0149] (((1))) A toner for developing electrostatic images, comprising toner particles containing a binder resin, a colorant, and a ferulic acid ester compound. (((2))) The toner for developing electrostatic images according to (((1))), wherein the ferulic acid ester compound comprises at least one selected from the group consisting of γ-oryzanols and ferulic acid alkyl ester compounds. (((3))) The toner for developing electrostatic images according to (((1))) or (((2))), wherein the ferulic acid ester compound contains a γ-oryzanol. (((4))) The toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein the content of the ferulic acid ester compound is 0.01% by mass or more and 20% by mass or less, based on the total mass of the toner particles. (((5))) The toner for developing electrostatic images according to any one of (((1))) to (((4))), wherein the ferulic acid ester compound includes a ferulic acid ester compound having a melting point of 150°C or higher and 185°C or lower. (((6))) The toner for developing electrostatic images according to any one of (((1))) to (((5))), wherein the binder resin contains a crystalline resin. (((7))) The toner for developing electrostatic images according to (((6))), wherein the crystalline resin contains a crystalline polyester resin. (((8))) An electrostatic image developer comprising the toner for developing electrostatic images according to any one of ((1))) to (((7))). (((9))) A toner cartridge that contains the toner for developing electrostatic images according to any one of (((1))) to (((7))) and is detachably mountable on an image forming apparatus. (((10))) A process cartridge that is detachably attached to an image forming apparatus, which contains the electrostatic image developer described in (((8))) and is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image. (((11))) An image forming apparatus comprising: an image carrier; charging means for charging the surface of the image carrier; electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; developing means that contains the electrostatic image developer described in (((8))) and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer; transfer means that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium; and fixing means that fixes the toner image transferred to the surface of the recording medium. (((12))) An image forming method comprising: a charging step of charging the surface of an image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer described in (((8))); a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0150] According to the invention related to (((1))) or (((2))), there is provided a toner for developing electrostatic images which has excellent discoloration suppression properties in the resulting images compared to toner particles which do not contain a ferulic acid ester compound. According to the invention related to (((3))), there is provided a toner for developing electrostatic images which is superior in suppressing discoloration in the resulting image compared to when the ferulic acid ester compound is a ferulic acid alkyl ester. According to the invention related to (((4))), there is provided a toner for developing electrostatic images which has better discoloration suppression properties in the resulting images than when the content of the ferulic acid ester compound is more than 20 mass % relative to the total mass of the toner particles. According to the invention related to (((5))), there is provided a toner for developing electrostatic images which has better discoloration suppression properties in the resulting image than when the ferulic acid ester compound contains only a ferulic acid ester compound having a melting point of less than 150°C. According to the invention related to (((6))), there is provided a toner for developing electrostatic images which has excellent heat storage properties compared to when the binder resin is an amorphous resin alone. According to the invention related to (((7))), there is provided a toner for developing electrostatic images which has superior heat storage stability compared to a case where the crystalline resin is a crystalline styrene-acrylic resin alone. According to the inventions of (((8))), (((9))), (((10))), (((11))) or (((12))), there are provided an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus or an image forming method which are excellent in suppressing discoloration in the resulting image compared to when the toner for developing electrostatic images contains toner particles which do not contain a ferulic acid ester compound. [Explanation of symbols]

[0151] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of charging means) 3. Exposure device (an example of an electrostatic image forming means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (an example of developing means) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer means) 6Y, 6M, 6C, 6K: Photoconductor cleaning device (an example of a cleaning means) 8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Drive Roll 24 Support Roll 26 Secondary transfer roll (an example of a secondary transfer means) 30 Intermediate transfer body cleaning device 107 Photosensitive body (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of transfer means) 113 Photosensitive drum cleaning device (an example of cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 118 Exposure opening 117 Cabinet 200 Process Cartridge 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. Binder resin, a colorant, and Toner particles containing a ferulic acid ester compound Toner for developing electrostatic images.

2. 2. The toner for developing electrostatic images according to claim 1, wherein the ferulic acid ester compound comprises at least one selected from the group consisting of γ-oryzanols and ferulic acid alkyl ester compounds.

3. 2. The toner for developing electrostatic images according to claim 1, wherein the ferulic acid ester compound comprises a γ-oryzanol.

4. 2. The toner for developing electrostatic images according to claim 1, wherein the content of the ferulic acid ester compound is 0.01% by mass or more and 20% by mass or less with respect to the total mass of the toner particles.

5. 2. The toner for developing electrostatic images according to claim 1, wherein the ferulic acid ester compound has a melting point of 150°C or higher and 185°C or lower.

6. 2. The toner for developing electrostatic images according to claim 1, wherein the binder resin comprises a crystalline resin.

7. 7. The toner for developing electrostatic images according to claim 6, wherein the crystalline resin comprises a crystalline polyester resin.

8. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 7.

9. A toner cartridge containing the toner for developing electrostatic images according to any one of claims 1 to 7, and being detachably mountable on an image forming apparatus.

10. 9. A process cartridge detachably mounted to an image forming apparatus, the process cartridge containing the electrostatic image developer according to claim 8 and comprising a developing means for developing an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image.

11. an image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; a developing unit containing the electrostatic image developer according to claim 8 and developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing unit for fixing the toner image transferred onto the surface of the recording medium. Image forming device.

12. a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to claim 8; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium. Image forming method.

Images