Electrostatic charge image developing toner, electrostatic charge image developer, toner cartridge, process cartridge, image forming device, and image forming method

Abstract

To provide an electrostatic charge image developing toner capable of nicely suppressing color fading due caused by ultraviolet light.SOLUTION: A core-shell electrostatic charge image developing toner comprising toner particles containing a binder resin and a florescent colorant is provided. A core contains the fluorescent colorant and a shell layer contains an ultraviolet absorbing agent as well as at least one selected form the group consisting of a radical scavenger and peroxide decomposer.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 electrophotographic (magenta) toner that uses the oil-soluble dye "CI Solvent Red 49" as a colorant, and that contains an antioxidant and a nickel complex compound as essential components.

[0003] Patent Document 2 discloses a toner for developing electrostatic latent images, which has a core layer containing a first binder resin and a colorant, and a shell layer containing a second binder resin and covering the core layer, and which is characterized in that the shell layer contains at least an ultraviolet inhibitor.

[0004] Patent Document 3 discloses a method for producing a toner, which includes a first step of mixing an ultraviolet absorber and / or an antioxidant with a dye and / or a pigment, and a second step of mixing the mixture obtained in the first step with a binder resin.

[0005] Patent Document 4 describes a toner containing a binder resin and a colorant, wherein the colorant contains a color pigment and a fluorescent dye, and the mass-based contents of the color pigment and the fluorescent dye in the toner are respectively W G , W F When the above W G and the aforementioned W F And, the following equation (1) WG×0.5>WF>WG×0.025 (1) and the absorption peak wavelength of the color pigment is P G and the emission peak wavelength of the fluorescent dye is P F When the above P G and the aforementioned P F And, the following equation (2) P G <PF (2) The toner is characterized by satisfying the following:

[0006] Patent Document 5 discloses a toner for developing electrostatic images, which is made of toner particles containing a binder resin, a colorant, and an ultraviolet absorber, and which is characterized in that the toner contains toner particles having a structure in which an intermediate layer is provided between a core layer containing at least a binder resin and a colorant and a shell layer formed so as to cover the core layer, and the intermediate layer contains an ultraviolet absorber. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-20653 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-133093 [Patent Document 3] JP-A-1-172976 [Patent Document 4] Japanese Patent Application Laid-Open No. 2017-3818 [Patent Document 5] Japanese Patent Application Laid-Open No. 2010-107617 Summary of the Invention [Problem to be solved by the invention]

[0008] The present disclosure addresses the problem of providing a core-shell type toner for developing electrostatic images, which has toner particles containing a binder resin and a fluorescent colorant, and which has excellent resistance to fading due to ultraviolet light compared to toners in which the shell layer does not contain an ultraviolet absorber or does not contain at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. [Means for solving the problem]

[0009] Specific means for solving the above problems include the following aspects. <1> A core-shell type toner for developing electrostatic images, which has toner particles containing a binder resin and a fluorescent colorant, wherein the core contains the fluorescent colorant, and the shell layer contains an ultraviolet absorber, and further contains at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. <2> The content of the ultraviolet absorber is 0.01% by mass or more and 10% by mass or less with respect to the total mass of the toner particles. <1> 2. The toner for developing electrostatic images according to claim 1. <3> The content of the ultraviolet absorber is 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the toner particles. <2> 2. The toner for developing electrostatic images according to claim 1. <4> The ultraviolet absorber contains a triazine compound. <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 total content of the radical scavenger and the peroxide decomposer is 0.05% by mass or more and 5% by mass or less with respect to the total mass of the toner particles. <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 radical scavenger contains a hindered amine compound. <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 peroxide decomposer comprises a phosphite compound. <1> ~ <6> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <8> The fluorescent colorant comprises a rhodamine compound. <1> ~ <7> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <9> <1> ~ <8> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9. <10> <1> ~ <8> 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. <11> <9> 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. <12> 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; <9> 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. <13> 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. <9> 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]

[0010] <1> or <8> According to the invention, there is provided a core-shell type toner for developing electrostatic images, which has toner particles containing a binder resin and a fluorescent colorant, and which has excellent resistance to fading due to ultraviolet light compared to a toner in which the shell layer does not contain an ultraviolet absorber or does not contain at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. <2> According to the invention, there is provided a toner for developing electrostatic images which has better color development properties than when the content of the ultraviolet absorber is more than 10% by mass with respect to the total mass of the toner particles. <3> According to the invention, a toner for developing electrostatic images is provided which has better color development properties than when the content of the ultraviolet absorber exceeds 1.5% by mass with respect to the total mass of the toner particles. <4> According to the invention, there is provided a toner for developing electrostatic images which is more excellent in suppressing discoloration due to ultraviolet light than when the ultraviolet absorber is a benzophenone compound. <5> According to the invention, there is provided a toner for developing electrostatic images that is more excellent in suppressing fading due to ultraviolet rays than when the total content of the radical scavenger and the peroxide decomposer is more than 5 mass % relative to the total mass of the toner particles. <6> According to the invention, there is provided a toner for developing electrostatic images which is more excellent in color development and in suppressing fading due to ultraviolet light than when the radical scavenger is a hydroquinone compound. <7> According to the invention, there is provided a toner for developing electrostatic images which is superior in color development and resistance to fading due to ultraviolet light compared to when the peroxide decomposer is a sulfur compound. <9> , <10> , <11> , <12> or <13> 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 is a core-shell type electrostatic image developer having toner particles containing a binder resin and a fluorescent colorant, and which has excellent resistance to fading due to ultraviolet light compared to a case where the shell layer does not contain an ultraviolet absorber or does not contain at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating the configuration of 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

[0012]

[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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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."

[0019] (Toner for developing electrostatic images) The toner for developing electrostatic images according to the present embodiment is a core-shell type toner for developing electrostatic images, having toner particles containing a binder resin and a fluorescent colorant, wherein the core contains the fluorescent colorant, the shell layer contains an ultraviolet absorber, and further contains at least one selected from the group consisting of a radical scavenger and a peroxide decomposer.

[0020] Conventional toners for developing electrostatic images have the problem that ultraviolet light decomposes fluorescent colorants when exposed to sunlight or when ultraviolet-curable varnishes (UV varnishes) are cured, generating radicals and active oxygen, which further decompose the fluorescent colorants and cause discoloration. In the toner for developing electrostatic images according to the present embodiment, the core contains the fluorescent colorant, and the shell layer contains an ultraviolet absorber and at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. This core-shell toner for developing electrostatic images is presumed to suppress decomposition of the fluorescent colorant by the radicals or active oxygen, and the radical scavenger or peroxide decomposer improves the dispersibility of the ultraviolet absorber, thereby enabling the toner to better exhibit ultraviolet absorption ability and provide excellent suppression of fading due to ultraviolet light. Furthermore, the toner for developing electrostatic images according to this embodiment also has excellent color development properties.

[0021] The configuration of the toner for developing electrostatic images according to this embodiment will be described in detail below.

[0022] [Toner particles] The toner particles are core-shell type toner for developing electrostatic images, having toner particles containing a binder resin and a fluorescent colorant, wherein the core contains the binder resin and the fluorescent colorant, the shell layer contains the binder resin and an ultraviolet absorber, and further contains at least one selected from the group consisting of a radical scavenger and a peroxide decomposer, and the core and shell layer contain a release agent and other additives as necessary.

[0023] <UV absorber> The toner particles contain an ultraviolet absorber in the shell layer. Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, triazine compounds, salicylic acid compounds, and oxalic acid diamide compounds.

[0024] The triazine compound may be any compound having a triazine structure, and examples thereof include 2-(4-butoxy-2-hydroxyphenyl)-4,6-bis(4-butoxyphenyl)-1,3,5-triazine, 2-(4-butoxy-2-hydroxyphenyl)-4,6-bis(2,4-dibutoxyphenyl)-1,3,5-triazine, 2,4-bis(4-butoxy-2-hydroxyphenyl)-6-(4-butoxyphenyl)-1,3,5-triazine, and 2,4-bis(4-butoxy-2-hydroxyphenyl)-6-(2,4-dibutoxyphenyl)- 1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3- 2-[4-(dodecyloxy / tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-(3-butoxy-2-hydroxypropoxy)phenyl)-1,3,5-triazine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine, 2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxy-propyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-(2-ethylhexyl)oxy)phenyl-4,6-bis(4-phenyl)phenyl-1,3,5-triazine, and the like.

[0025] The benzotriazole compound may be any compound having a benzotriazole structure, such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-dodecyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(2'-hydroxy-3'-(3,4,5,6-tetrahydrophthalimidylmethyl)-5'-methylbenzyl)phenyl)benzotriazole, 2-(3'-sec-butyl-5'-t-butyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(α,α-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, 2-(3'-t-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-t-butyl-5'-[2-(2-ethylhexyloxy)-carbonylethyl]-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-t-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-t-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, Examples include 2-(3'-t-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3'-t-butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3'-t-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenylbenzotriazole, and 2,2'-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazol-2-ylphenol].

[0026] The benzophenone compound may be any compound having a benzophenone structure, and examples thereof include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-decyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-(2-hydroxy-3-methacryloxypropoxy)benzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2- Examples of suitable hydroxybenzophenones include hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2-hydroxy-4-diethylamino-2'-hexyloxycarbonylbenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 1,4-bis(4-benzyloxy-3-hydroxyphenoxy)butane.

[0027] The salicylic acid compound may be any compound having a salicylic acid structure, and examples thereof include phenyl salicylate, 4-t-butylphenyl salicylate, 4-octylphenyl salicylate, dibenzoylresorcinol, bis(4-t-butylbenzoyl)resorcinol, benzoylresorcinol, 2,4-di-t-butylphenyl 3,5-di-t-butyl-4-hydroxysalicylate, and hexadecyl 3,5-di-t-butyl-4-hydroxysalicylate.

[0028] Among these, it is preferable that the ultraviolet absorber contains a triazine compound from the viewpoint of suppressing fading due to ultraviolet rays.

[0029] The ultraviolet absorber may be contained alone or in combination of two or more. The content of the ultraviolet absorber is preferably from 0.01% by mass to 10% by mass, more preferably from 0.02% by mass to 5% by mass, even more preferably from 0.1% by mass to 2.0% by mass, and particularly preferably from 0.2% by mass to 1.5% by mass, relative to the total mass of the toner particles, from the viewpoints of color development and suppression of fading due to ultraviolet rays.

[0030] <Radical scavenger> From the viewpoint of color development and suppression of fading due to ultraviolet rays, the toner particles preferably contain a radical scavenger in the shell layer. Examples of the radical scavenger include phenol compounds, hindered amine compounds, hydroquinone compounds, phenothiazine compounds, nitroso compounds, and N-oxyl compounds.

[0031] Examples of the hindered phenol compounds include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, mono(or di- or tri)(α-methylbenzyl)phenol, 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 2,5-di- tert-Butylhydroquinone, 2,5-di-tert-amylhydroquinone, triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene , bis[3,5-di-t-butyl-4-hydroxybenzyl(ethoxy)phosphinate]calcium, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 2,4-2,4-bis[(octylthio)methyl]o-cresol, N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, tris(2,4-di-t-butylphenyl)phosphite, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)-benzotriazole Examples include benzotriazole, methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate-polyethylene glycol (molecular weight approximately 300) condensate, hydroxyphenylbenzotriazole derivatives, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), and 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate.

[0032] Among these, the radical scavenger is preferably a phenol compound or a hindered amine compound, more preferably a hindered amine compound, from the viewpoint of color development and suppression of fading due to ultraviolet light.

[0033] The radical scavenger may be contained alone or in combination of two or more. From the viewpoint of color development and suppression of fading due to ultraviolet light, the content of the radical scavenger is preferably from 0.01% by mass to 5% by mass, more preferably from 0.01% by mass to 2% by mass, even more preferably from 0.05% by mass to 1.0% by mass, and particularly preferably from 0.1% by mass to 0.8% by mass, relative to the total mass of the toner particles.

[0034] <Peroxide decomposer> From the viewpoint of color development and suppression of fading due to ultraviolet light, the toner particles preferably contain a peroxide decomposer in the shell layer, and more preferably contain both a radical scavenger and a peroxide decomposer in the shell layer. Examples of peroxide decomposers include those used as antioxidants, such as sulfur compounds (such as thioether compounds), phosphorus compounds, dithiocarbamate compounds, thiourea compounds, and benzimidazole compounds.

[0035] Examples of peroxide decomposers include sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate, and phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-t-butylphenyl) phosphite.

[0036] Among these, from the viewpoint of color development and suppression of fading due to ultraviolet light, phosphorus compounds are preferred as peroxide decomposers, and phosphite compounds are more preferred.

[0037] The peroxide decomposer may be contained alone or in combination of two or more. From the viewpoint of color development and suppression of fading due to ultraviolet light, the content of the peroxide decomposer is preferably from 0.01% by mass to 5% by mass, more preferably from 0.01% by mass to 2% by mass, even more preferably from 0.02% by mass to 1.0% by mass, and particularly preferably from 0.05% by mass to 0.8% by mass, relative to the total mass of the toner particles.

[0038] From the viewpoint of color development and suppression of fading due to ultraviolet light, the total content of the radical scavenger and the peroxide decomposer is preferably from 0.01% by mass to 5% by mass, more preferably from 0.01% by mass to 2% by mass, even more preferably from 0.02% by mass to 1.0% by mass, and particularly preferably from 0.05% by mass to 0.8% by mass, relative to the total mass of the toner particles.

[0039] <Fluorescent colorants> The core includes a fluorescent colorant. The fluorescent colorant may be any colorant that exhibits fluorescence, but is preferably a colorant that exhibits fluorescence in the visible light region (wavelengths of 380 nm or more and 760 nm or less). The light that excites the fluorescent colorant is not particularly limited, but preferably contains at least visible light or ultraviolet light, and more preferably contains at least ultraviolet light. Furthermore, the fluorescent colorant may be either a fluorescent pigment or a fluorescent dye, but is preferably a fluorescent dye. In this embodiment, a "pigment" is a colorant whose solubility in 100 g of water at 23°C and in 100 g of cyclohexanone at 23°C is less than 0.1 g, and a "dye" is a colorant whose solubility in 100 g of water at 23°C or in 100 g of cyclohexanone at 23°C is 0.1 g or more.

[0040] The color of the fluorescent colorant is not particularly limited and may be selected appropriately as desired. Examples of fluorescent colorants include fluorescent pink colorants, fluorescent red colorants, fluorescent orange colorants, fluorescent yellow colorants, fluorescent green colorants, and fluorescent purple colorants. Among these, a fluorescent pink colorant, a fluorescent red colorant, a fluorescent orange colorant, a fluorescent yellow colorant, or a fluorescent green colorant is preferred, a fluorescent pink colorant, a fluorescent yellow colorant, or a fluorescent green colorant is more preferred, and a fluorescent pink colorant is even more preferred. Among these, it is particularly preferable that the fluorescent colorant contains a rhodamine compound, from the viewpoint of further exerting the effects of this embodiment.

[0041] The fluorescent peak wavelength in the spectral reflectance of the fluorescent colorant can be appropriately selected depending on the desired color. For example, if a fluorescent pink color is desired, the fluorescent peak wavelength is preferably 560 nm or more and 670 nm or less, and more preferably 580 nm or more and 650 nm or less. An example of the spectrum for each fluorescent color is shown below. The vertical axis represents the fluorescence intensity, and the horizontal axis represents the wavelength. Note that "mμ" = "nm."

[0042]

change

[0043] As the fluorescent colorant, known fluorescent colorants can be used, and specific examples thereof include CI Pigment Yellow 101, Basic Red 1 (Rhodamine 6G), Basic Red 1:1, Basic Red 2, Basic Red 12, Basic Red 13, Basic Red 14, Basic Red 15, Basic Red 36, Basic Violet 7, Basic Violet 10 (Rhodamine B), Basic Violet 11 (Rhodamine 3B), Basic Violet 11:1 (Rhodamine A), Basic Violet 15, Basic Violet 16, Basic Violet 27, Pigment Yellow 101, Basic Yellow 1, Basic Yellow 2, Basic Yellow 9, Basic Yellow 24, Basic Yellow 40, Basic Orange 15, Basic Orange 22, Basic Blue 1, Basic Blue 3, Basic Blue 7, Basic Blue 9, Basic Blue 45, Basic Green 1, Acid Yellow 3, and Acid Yellow. 7, Acid Yellow 73, Acid Yellow 87, Acid Yellow 184, Acid Yellow 245, Acid Yellow 250, Acid Red 51, Acid Red 52, Acid Red 57, Acid Red 77, Acid Red 87, Acid Red 89, Acid Red 92, Acid Blue 9, Acid Black 2, Solvent Yellow 43, Solvent Yellow 44, Solvent Yellow 85, Solvent Yellow 98, Solvent Yellow 116, Solvent Yellow 131, Solvent Yellow 145, Solvent Yellow 160:1, Solvent Yellow 172, Solvent Yellow 185, Solvent Yellow 195, Solvent Yellow 196, Solvent Orange 63, Solvent Orange112, Solvent Red 49, Solvent Red 149, Solvent Red 175, Solvent Red 196, Solvent Red 197, Solvent Blue 5, Solvent Green 5, Solvent Green 7, Direct Yellow 27, Direct Yellow 85, Direct Yellow 96, Direct Orange 8, Direct Red 2, Direct Red 9, Direct Blue 22, Direct Blue 199, Direct Green 6, Disperse Yellow 11, Disperse Yellow 82, Disperse Yellow 139, Disperse Yellow 184, Disperse Yellow 186, Disperse Yellow 199, Disperse Yellow 202, Disperse Yellow 232, Disperse Orange 11, Disperse Orange 32, Disperse Red 58, Disperse Red 274, Disperse Red 277, Disperse Red 303, Disperse Blue 7, Reactive Yellow 78, Vat Red 41, etc.

[0044] The fluorescent colorant may be contained alone or in combination of two or more kinds. The content of the fluorescent colorant is preferably 0.1% by mass to 30% by mass, more preferably 0.2% by mass to 15% by mass, based on the total mass of the toner particles, from the viewpoints of fluorescence intensity and image graininess.

[0045] <Colorants other than fluorescent colorants> The toner particles may contain a colorant other than the fluorescent colorant, preferably a non-fluorescent pigment. The colorant other than the fluorescent colorant may be contained in the core, the shell layer, or both. Specific examples of colorants other than fluorescent colorants include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 21, 22, 23, 31, 32, 38, 41, 48, 48:1, and 48: 2, 48:3, 48:4, 49, 52, 53:1, 54, 57:1, 58, 60:1, 63, 64:1, 68, 81:1, 81:4, 83, 88, 89, 112, 114, 122, 123, 144, 146, 149, 150, 166, 170 , 176, 177, 178, 179, 184, 185, 187, 202, 206, 207, 208, 209, 210, 220, 221, 238, 242, 245, 253, 254, 255, 256, 258, 264, 266, 269, 28 2nd class, magenta pigments such as Pigment Violet 19, CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63, 81, 82, 83, 84, 100, 109, 111, 121, 122, CI Disperse Red 9, CIMagenta dyes such as Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, and 40, red iron oxide, cadmium red, red lead, mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rotamine lake B, alizarin lake, brilliant carmine 3B, carbon black, black Examples of suitable pigments include various pigments such as Benzidine Yellow, Hansa Yellow, Benzidine Yellow, Threne Yellow, Quinoline Yellow, Pigment Yellow, Permanent Orange GTR, Pyrazolone Orange, Balkan Orange, Brilliant Carmine 3B, Brilliant Carmine 6B, DuPont Oil Red, Lake Red C, Aniline Blue, Ultramarine Blue, Chalco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, and Malachite Green Oxalate, as well as various dyes. The colorants other than the fluorescent colorant may be used alone or in combination of two or more.

[0046] The colorants other than the fluorescent 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.

[0047] The content of colorants other than fluorescent colorants is preferably 0.1% by mass to 30% by mass, more preferably 0.5% by mass to 15% by mass, based on the total fluorescent toner particles, from the viewpoint of fluorescence intensity and color reproducibility.

[0048] <Binder resin> The toner particles preferably contain a binder resin, and the core and shell layers preferably contain the 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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."

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Here, the polyhydric alcohol has an aliphatic diol content of 80 mol % or more, preferably 90 mol % or more.

[0061] 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) 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."

[0062] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0063] The crystalline polyester resin can be obtained by a known manufacturing method, for example, in the same manner as the amorphous polyester.

[0064] 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.

[0065] <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.

[0066] 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."

[0067] 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.

[0068] <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.

[0069] <Characteristics of toner particles> The toner particles have a so-called core-shell structure, which is composed of a core and a coating layer (shell layer) that covers the core.

[0070] 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.

[0071] 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:

[0072] 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.

[0073] 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.

[0074] [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.

[0075] 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.

[0076] 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).

[0077] 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.

[0078] [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.

[0079] 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.

[0080] 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 to be a binder resin are dispersed (a resin particle dispersion preparation step); a step of preparing a fluorescent colorant dispersion in which a fluorescent colorant is dispersed (a fluorescent colorant dispersion preparation step); a step of aggregating the mixed particles in a mixed dispersion obtained by mixing a resin particle dispersion and a fluorescent 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).

[0081] Each step will be described in detail below.

[0082] -Resin particle dispersion preparation process- The resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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, Ltd. LA-700), and the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the smallest particle size side. The particle size at which the cumulative 50% of all particles is obtained is defined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same manner.

[0087] 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.

[0088] In the same manner as the binder resin particle dispersion, for example, a fluorescent colorant particle dispersion, a release agent particle dispersion, and an ultraviolet absorber dispersion can also be prepared. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the binder resin particle dispersion are the same for the fluorescent colorant particles dispersed in the fluorescent colorant particle dispersion, the release agent particles dispersed in the release agent particle dispersion, and the ultraviolet absorber dispersed in the ultraviolet absorber dispersion. The radical scavenger dispersion and the peroxide decomposer dispersion can be obtained, for example, by dissolving a radical scavenger and a peroxide decomposer in a dispersion medium. Examples of the dispersion medium used in the radical scavenger dispersion and the peroxide decomposer dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water, and alcohols. These may be used alone or in combination of two or more. The content of the radical scavenger dispersion and the peroxide decomposer in the radical scavenger dispersion and the peroxide decomposer 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.

[0089] -Agglomerated particle formation process- A resin particle dispersion, a fluorescent colorant particle dispersion, and a release agent particle dispersion are mixed together, and the resin particles, the fluorescent colorant, and the release agent particles are hetero-aggregated in the mixed dispersion to form aggregated particles containing the resin particles, the fluorescent colorant, and the release agent particles, which have a diameter close to that of the target toner particles.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] -Second agglomerated particle formation process and fusion / coalescence process- After obtaining an aggregated particle dispersion in which aggregated particles are dispersed, the aggregated particle dispersion, a resin particle dispersion in which resin particles are dispersed, an ultraviolet absorber dispersant in which an ultraviolet absorber is dispersed, and a radical The core-shell toner particles are produced through the following steps: a step of further mixing the radical scavenger dispersion liquid in which the scavenger is dissolved with the peroxide decomposer dispersion liquid in which the peroxide decomposer is dissolved, and agglomerating the particles so that resin particles, UV absorber, radical scavenger, and peroxide decomposer are further attached to the surfaces of the aggregated particles to form second aggregated particles; and a step of heating the second aggregated particle dispersion liquid in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles to form core-shell toner particles. In the fusion / coalescence process, the dispersion liquid in which the second aggregate 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 second aggregate particles and form core-shell toner particles. Through the above steps, core-shell toner particles are obtained.

[0094] 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.

[0095] 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.

[0096] (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.

[0097] 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.

[0098] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] (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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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 means) 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).

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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 transferred onto the intermediate transfer belt 20 in a superimposed manner.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] <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.

[0121] 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.

[0122] 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.

[0123] 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).

[0124] 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.

[0125] 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]

[0126] 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.

[0127] Example 1 [Toner Preparation] <Preparation of fluorescent colorant dispersion> Rhodamine fluorescent colorant (Tokyo Chemical Industry Co., Ltd., Rhodamine 6G): 15.8 parts Acetylacetone metal compound: 34.2 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts Ion-exchanged water: 193 parts The above components were mixed and treated for 10 minutes at 240 MPa using an Ultimizer (manufactured by Sugino Machine Co., Ltd.) to prepare a fluorescent colorant dispersion (solid concentration: 20%).

[0128] <Preparation of Resin Particle Dispersion (1)> -Oil phase materials- Dodecanedioic acid (Tokyo Chemical Industry Co., Ltd.): 20.8 parts 1,9-nonanediol (Tokyo Chemical Industry Co., Ltd.): 20.5 parts Dodecanethiol (Fujifilm Wako Pure Chemical Industries, Ltd.): 0.4 parts

[0129] -Ingredients for aqueous phase 1- Ion-exchanged water: 17 parts Anionic surfactant: Dowfax (Dow Chemical Company): 0.4 parts

[0130] -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

[0131] The oil phase materials and the aqueous phase 1 materials were separately stirred and mixed, and the two were stirred and mixed to form an emulsion dispersion of monomer. Separately, the aqueous phase 2 materials were added to a reaction vessel, 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 monomer was gradually added dropwise to the reaction vessel over 3 hours to carry out emulsion polymerization. After the dropwise addition was completed, the polymerization was continued at 75°C and terminated after 3 hours, yielding a resin particle dispersion with a solid content of 42% by mass. Ion-exchange water was added to the resin particle dispersion to adjust the solid content to 20%, yielding resin particle dispersion (1). 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.

[0132] <Preparation of Resin Particle Dispersion (2)> Resin particle dispersion (2) was obtained in the same manner as in the preparation of resin particle dispersion (1), except that the material of the oil phase of resin particle dispersion (1) was changed as follows:

[0133] -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

[0134] 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.

[0135] <Preparation of Release Agent Particle Dispersion> Paraffin wax (Nippon Seiro Co., Ltd., HNP-9): 100 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1 part Ion-exchanged water: 350 parts The above materials were mixed and heated to 100°C, dispersed using a homogenizer (IKA, trade name Ultra Turrax T50), and then dispersed using a Manton-Gaulin high-pressure homogenizer (Gaulin) to obtain a release agent particle dispersion (1) (solid content 20% by mass) in which release agent particles with a volume average particle size of 200 nm were dispersed.

[0136] <Preparation of UV absorber dispersion (1)> Triazine compound (Fujifilm Wako Pure Chemical Industries, Ltd., triazine standard): 5 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1 part Ion-exchanged water: 94 parts The above materials were mixed and heated to 100°C, dispersed using a homogenizer (IKA, trade name Ultra Turrax T50), and then dispersed using a Manton-Gaulin high-pressure homogenizer (Gaulin) to obtain an ultraviolet absorber dispersion (1) (solid content 5% by mass).

[0137] <Preparation of Radical Scavenger Dispersion (1)> Hindered amine compound (ADEKA Corporation, Adekastab LA-52): 5 parts Ion-exchanged water: 95 parts The above components were mixed to obtain a radical scavenger dispersion (solid content: 5% by mass).

[0138] <Preparation of Peroxide Decomposer Dispersion (1)> Phosphite compound (Fujifilm Wako Pure Chemical Industries, Ltd., tris(2,4-di-t-butylphenyl)phosphite standard): 5 parts Ion-exchanged water: 95 parts The above components were mixed to obtain a peroxide decomposer dispersion (solid content: 5% by mass).

[0139] <Preparation of toner particles> -Materials (1)- Fluorescent colorant dispersion (1): 20 parts ·Resin particle dispersion (1): 390 parts Release agent particle dispersion (1): 40 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd.: Neogen RK, 20%): 1 part

[0140] -Materials (2)- ·200 parts of resin particle dispersion (1) UV absorber dispersion (1) 11 parts Radical scavenger dispersion (1) 8 parts Peroxide decomposer dispersion (1) 8 parts

[0141] Material (1) was placed in a round stainless steel flask and adjusted to pH 3.5 with 0.1 N (=mol / L) nitric acid. Then, 30 parts of a nitric acid solution containing 10% by weight of aluminum sulfate were added. The mixture was then dispersed at 30°C using a homogenizer (Ultra Turrax T50, manufactured by IKA Corporation) and heated to 45°C in a heating oil bath for 30 minutes. Material (2) was then added and maintained for 1 hour. The pH was adjusted to 8.5 with the addition of 0.1 N (=mol / L) aqueous sodium hydroxide solution, and the mixture was then heated to 85°C and maintained for 2.5 hours. The mixture was then cooled to 20°C at a rate of 20°C / min. The solids were filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles. The volume average particle size of the toner particles was 5 μm.

[0142] <Creating the carrier> 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 Ωcm or less). The above materials except for the ferrite particles were dispersed in a sand mill to prepare a dispersion, and this dispersion together with the ferrite particles was placed in a vacuum degassing kneader, and the carrier was obtained by drying under reduced pressure while stirring.

[0143] <Toner Production> 100 parts by mass of the obtained toner particles were mixed and blended with 1.5 parts by mass of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., RY50) and 1.0 part by mass of hydrophobic titanium oxide (manufactured by Nippon Aerosil Co., Ltd., T805) using a sample mill at 10,000 rpm (revolutions per minute) for 30 seconds. The mixture was then sieved through a vibrating sieve with 45 μm openings to prepare toner (1) (toner for developing electrostatic images). The volume average particle size of the obtained toner was 7 μm.

[0144] <Preparation of Electrostatic Image Developer> 8 parts of the toner and 92 parts of the carrier were mixed in a V blender to prepare developer A (electrostatic image developer).

[0145] (Examples 2 to 5, Examples 10 to 19, and Comparative Examples 1 to 5) An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the amounts of the ultraviolet absorber, radical scavenger, and peroxide decomposer were adjusted to the respective contents shown in Table 1.

[0146] Example 6 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the ultraviolet absorber in the ultraviolet absorber dispersion (1) was changed to a benzophenone compound (benzophenone, manufactured by Tokyo Chemical Industry Co., Ltd.).

[0147] Example 7 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the radical scavenger in the radical scavenger dispersion (1) was changed to a hydroquinone compound (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hydroquinone).

[0148] Example 8 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the peroxide decomposer in the peroxide decomposer dispersion (1) was changed to a thiourea compound (manufactured by Tokyo Chemical Industry Co., Ltd., chiral isothiourea).

[0149] Example 9 An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the resin particle dispersion (1) was changed to the resin particle dispersion (2).

[0150] (Comparative Example 3: Non-core-shell toner particles) An electrostatic image developing toner and an electrostatic image developer were prepared in the same manner as in Example 1, except that the toner particles were prepared as follows. -material- Fluorescent colorant dispersion (1): 20 parts ·Resin particle dispersion (1): 590 parts Release agent particle dispersion (1): 40 parts UV absorber dispersion (1) 11 parts Radical scavenger dispersion (1) 8 parts Peroxide decomposer dispersion (1) 8 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd.: Neogen RK, 20%): 1 part The above materials were placed in a round stainless steel flask, and 0.1 N nitric acid was added to adjust the pH to 3.5. Then, 30 parts of a nitric acid solution containing 10% aluminum sulfate by weight were added. The mixture was then dispersed at 30°C using a homogenizer (Ultra Turrax T50, manufactured by IKA Corporation). The mixture was then heated to 45°C in a heating oil bath and held for 2 hours. 0.1 N aqueous sodium hydroxide was added to adjust the pH to 8.5, and the mixture was then heated to 85°C and held for 2.5 hours. The mixture was then cooled to 20°C at a rate of 20°C / min. The solids were filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles. The volume average particle size of the toner particles was 5 μm.

[0151] The resulting toner for developing electrostatic images and the electrostatic image developer were used to carry out the following evaluations.

[0152] <Evaluation of color development and UV fading prevention> The developer using the above toner was installed in a modified Revori Press PC1120 printer manufactured by Fujifilm Business Innovation Co., Ltd., and the toner weight on the paper was measured at 20°C and 50% humidity. 2 The image was adjusted so that a 5 cm x 5 cm solid was formed on J paper manufactured by Fujifilm Business Innovation Co., Ltd. in monochrome mode, and used as an image sample.

[0153] The color density of the obtained image sample was measured using a densitometer (X-Rite 938, manufactured by X-Rite Corporation) and used as a reference color. Next, a photo-radical polymerizable UV varnish, "UV VECTA Coat Varnish PC-3KW2" (manufactured by T&K TOKA Corporation), was applied to this image sample using a wire bar to a thickness of 6 μm, and the integrated light intensity of the fixed image surface was set to 100 mJ / cm using an ultraviolet irradiation device with a mercury lamp as the light source. 2 The UV varnish was cured by irradiating it with ultraviolet light until a varnish layer was formed. The color density of the image sample before and after UV varnish processing was then measured using the densitometer described above. From these measurements, the color difference between before and after UV varnish processing, ΔE = [(L before - L after) 2 +(before a-after a) 2 +(before b-after b) 2 ] 1 / 2 The values ​​of L, a, and b are respectively before UV varnishing, and L, a, and b are respectively after UV varnishing. The evaluation criteria for ΔE are as follows: The smaller the ΔE value, the better the resistance to fading due to ultraviolet rays, and A to C are ratings that are acceptable for practical use. A: ΔE is less than 0.5 B: ΔE is 0.5 or more and less than 1.5 C: ΔE is 1.5 or more and less than 3.0 D: ΔE is 3.0 or more

[0154] The difference ΔE2 between the color before or after UV varnishing and the target color (target color DIC584B) was calculated using the following formula: LTC, aTC, and bTC represent L, a, and b of the target color, respectively. ΔE2=[(Before L-LTC) 2 +(a before -aTC) 2 +(bbefore-bTC) 2 ] 1 / 2 The evaluation criteria for ΔE2 are as follows: The smaller the ΔE2 value, the better the color development, and A to C are evaluations that present no practical problems. A: ΔE2 is less than 0.2 B: ΔE2 is 0.2 or more and less than 0.4 C: ΔE2 is 0.4 or more and less than 0.6 D: ΔE2 is 0.6 or more

[0155] The evaluation results are summarized in Table 1.

[0156] [Table 1]

[0157] The contents of the ultraviolet absorber, radical scavenger, and peroxide decomposer in Table 1 are the amounts relative to the total mass of the toner particles.

[0158] As shown in Table 1, the electrostatic image developing toners of Examples 1 to 17 were superior to the electrostatic image developing toners of Comparative Examples 1 to 3 in suppressing fading due to ultraviolet light.

[0159] Specific means for solving the above problems include the following aspects. (((1))) A core-shell type toner for developing electrostatic images, having toner particles containing a binder resin and a fluorescent colorant, wherein the core contains the fluorescent colorant, the shell layer contains an ultraviolet absorber, and the toner for developing electrostatic images further contains at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. (((2))) The toner for developing electrostatic images according to (((1))), wherein the content of the ultraviolet absorber is 0.01% by mass or more and 10% by mass or less with respect to the total mass of the toner particles. (((3))) The toner for developing electrostatic images according to (((2))), wherein the content of the ultraviolet absorber is 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the toner particles. (((4))) The toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein the ultraviolet absorber contains a triazine compound. (((5))) The toner for developing electrostatic images according to any one of (((1) to (((4))), wherein the total content of the radical scavenger and the peroxide decomposer is 0.05% by mass or more and 5% by mass or less, based on the total mass of the toner particles. (((6))) The toner for developing electrostatic images according to any one of (((1))) to (((5))), wherein the radical scavenger contains a hindered amine compound. (((7))) The toner for developing electrostatic images according to any one of (((1))) to (((6))), wherein the peroxide decomposer contains a phosphite compound. (((8))) The toner for developing electrostatic images according to any one of (((1))) to (((7))), wherein the fluorescent colorant contains a rhodamine compound. (((9))) An electrostatic image developer comprising the toner for developing electrostatic images according to any one of ((1))) to (((8))). (((10))) A toner cartridge that contains the electrostatic image developing toner according to any one of ((1))) to (((8))) and is detachably mountable on an image forming apparatus. (((11))) A process cartridge that is detachably mounted to an image forming apparatus, which contains the electrostatic image developer described in (((9))) 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. (((12))) 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 (((9))) 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. (((13))) 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 (((9))); 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.

[0160] According to the invention related to (((1))) or (((8))), there is provided a core-shell type electrostatic image developing toner having toner particles containing a binder resin and a fluorescent colorant, wherein the shell layer of the toner is excellent in suppressing fading due to ultraviolet light compared to a toner that does not contain an ultraviolet absorber or does not contain at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. According to the invention related to (((2))), a toner for developing electrostatic images is provided which has better color development properties than when the content of the ultraviolet absorber is more than 10% by mass with respect to the total mass of the toner particles. According to the invention related to (((3))), a toner for developing electrostatic images is provided which has better color development properties than when the content of the ultraviolet absorber is more than 1.5 mass % with respect to the total mass of the toner particles. According to the invention related to (((4))), there is provided a toner for developing electrostatic images which is more excellent in suppressing fading due to ultraviolet light than when the ultraviolet absorber is a benzophenone compound. According to the invention related to (((5))), there is provided a toner for developing electrostatic images which is more excellent in suppressing fading due to ultraviolet rays than when the total content of the radical scavenger and the peroxide decomposer is more than 5 mass % relative to the total mass of the toner particles. According to the invention related to (((6))), there is provided a toner for developing electrostatic images which is superior in color development and in suppressing fading due to ultraviolet light compared to when the radical scavenger is a hydroquinone compound. According to the invention related to (((7))), there is provided a toner for developing electrostatic images which is superior in color development and resistance to fading due to ultraviolet light compared to when the peroxide decomposer is a sulfur compound. According to the inventions of (((9))), (((10))), (((11))), (((12))) or (((13))), there is provided an electrostatic image developer, toner cartridge, process cartridge, image forming apparatus or image forming method, which is a core-shell type electrostatic image developing toner having toner particles containing a binder resin and a fluorescent colorant, and which has excellent resistance to fading due to ultraviolet light compared to when the shell layer does not contain an ultraviolet absorber or does not contain at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. [Explanation of symbols]

[0161] 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 Photoconductor (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. A core-shell type toner for developing electrostatic images, comprising toner particles containing a binder resin and a fluorescent colorant, the core comprises the fluorescent colorant; The shell layer contains an ultraviolet absorber and further contains at least one selected from the group consisting of a radical scavenger and a peroxide decomposer. Toner for developing electrostatic images.

2. 2. The toner for developing electrostatic images according to claim 1, wherein the content of the ultraviolet absorber is 0.01% by mass or more and 10% by mass or less with respect to the total mass of the toner particles.

3. 3. The toner for developing electrostatic images according to claim 2, wherein the content of the ultraviolet absorber is 0.1% by mass or more and 1.5% by mass or less with respect to the total mass of the toner particles.

4. 2. The toner for developing electrostatic images according to claim 1, wherein the ultraviolet absorber comprises a triazine compound.

5. 2. The toner for developing electrostatic images according to claim 1, wherein the total content of the radical scavenger and the peroxide decomposer is 0.05% by mass or more and 5% by mass or less with respect to the total mass of the toner particles.

6. 2. The toner for developing electrostatic images according to claim 1, wherein the radical scavenger comprises a hindered amine compound.

7. 2. The toner for developing electrostatic images according to claim 1, wherein said peroxide decomposer comprises a phosphite compound.

8. 2. The toner for developing electrostatic images according to claim 1, wherein said fluorescent colorant comprises a rhodamine compound.

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

10. A toner cartridge containing the toner for developing electrostatic images according to any one of claims 1 to 8, which is detachably mountable on an image forming apparatus.

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

12. 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 9 and developing the electrostatic image formed on the surface of the image carrier into a toner image by 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.

13. 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 9; 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