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

Abstract

An electrostatic charge image developing toner set, an electrostatic charge image developer set, a toner cartridge set, a process cartridge, an image forming apparatus, and a method are provided, the electrostatic charge image developing toner set including: a black toner having black toner particles; and a magenta toner having magenta toner particles, the binder resin including an amorphous polyester resin and a crystalline polyester resin, the crystalline polyester resin being contained in an amount of 7-40 mass% relative to the binder resin, mass ratio (mass%) P (K) of structural unit derived from phthalic acid other than terephthalic acid to structural unit derived from polycarboxylic acid in amorphous polyester resin contained in black toner particles The mass ratio (mass%) P (M) of a structural unit derived from a phthalic acid other than terephthalic acid to a structural unit derived from a polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles satisfies 10 < = P (M)-P (K) < = 40.

Description

Technical Field

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

[0002] Patent Document 1 discloses “a toner characterized by containing at least a polyester resin having specific structural units.”

[0003] Patent document 2 discloses "a full-color toner composed of a black toner and at least one color toner each containing a binder resin and a colorant, wherein the aromatic concentration of the binder resin contained in the black toner (black toner aromatic concentration) is lower than the aromatic concentration of the binder resin contained in any color toner (color toner aromatic concentration), the difference between the black toner aromatic concentration and the lowest color aromatic concentration is greater than any difference between the color toner aromatic concentrations, and the difference between the black toner aromatic concentration and the aromatic concentration of any color toner is 1 to 14 weight %."

[0004] Patent document 3 discloses "a full-color toner composed of a black toner and at least one color toner each containing a binder resin and a colorant, wherein the unsaturation of the binder resin contained in the black toner (black toner unsaturation) is lower than the unsaturation of the binder resin contained in any color toner (color toner unsaturation), the difference between the unsaturation of the black toner and the lowest unsaturation of the color toner is greater than any difference between the unsaturations of the color toners, and the difference between the unsaturation of the black toner and the unsaturation of any color toner is 0.1 to 1.5 mol / 1000 g."

[0005] Patent document 4 discloses "an image forming method, which includes: an electrostatic image forming process, forming an electrostatic image on the surface of an image retaining body; a developing process, developing the electrostatic image using a black toner for light fixing and a color toner for light fixing to form a black toner image and a color toner image; a transferring process, transferring the black toner image and the color toner image formed in the developing process to the surface of a transfer body; and a light fixing process, fixing the black toner image and the color toner image transferred to the surface of the transfer body by exposure to light in the infrared region, the black toner being a black toner melted by exposure to light in the infrared region in the light fixing process, and the color toner being a color toner containing an infrared absorber, the light absorption rate at the peak wavelength of the light in the infrared region irradiated in the light fixing process being 79% or more and 98% or less relative to the light absorption rate of the black toner at the peak wavelength, and the color difference ΔE being 20 or less."

[0006] Patent Document 5 discloses “a toner set for electrostatic image development, comprising two or more toners of different hues, wherein the difference between the maximum and minimum values ​​of the absorbance α of each toner at 380 to 1,500 nm is 0.1 or less.”

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-257363

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-361520

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2004-361817

[0010] Patent Document 4: Japanese Patent Application Laid-Open No. 2010-230914

[0011] Patent Document 5: Japanese Patent Application Laid-Open No. 2011-43662 Summary of the Invention

[0012] An object of the present invention is to provide a toner set for electrostatic image development, wherein, compared to a toner comprising black toner particles containing a binder resin and a black colorant and a magenta toner particles containing a binder resin and a magenta colorant, the binder resins of the black toner particles and the magenta toner particles contain an amorphous polyester resin and a crystalline polyester resin, and the content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less, the relationship between the mass ratio (mass %) P(K) of structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles does not satisfy Formula (P1), thereby ensuring low-temperature fixing ability and suppressing unevenness in gloss of black and magenta images caused by exposure to the outdoors.

[0013] Means for solving the above-mentioned problems include the following.

[0014] <1>

[0015] A toner set for developing electrostatic images, comprising:

[0016] A black toner having black toner particles containing a binder resin and a black colorant; and

[0017] A magenta toner having magenta toner particles containing a binder resin and a magenta colorant,

[0018] The binder resin contained in the black toner particles and the magenta toner particles includes an amorphous polyester resin and a crystalline polyester resin.

[0019] The content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less,

[0020] The amorphous polyester resin contained in the black toner particles and the magenta toner particles is composed of a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol.

[0021] The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles satisfies the following formula (P1).

[0022] Formula (P1): 10≤P(M)-P(K)≤40

[0023] <2>

[0024] The electrostatic image developing toner set according to <1>, wherein

[0025] The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the magenta toner particles satisfies the following formula (P2).

[0026] Formula (P2): 15≤P(M)-P(K)≤35

[0027] <3>

[0028] The electrostatic image developing toner set according to <1> or <2>, wherein

[0029] The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 11 mass % or more and 80 mass % or less.

[0030] <4>

[0031] The electrostatic image developing toner set according to <3>, wherein

[0032] The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 15 mass % or more and 50 mass % or less.

[0033] <5>

[0034] The electrostatic image developing toner set according to any one of <1> to <4>, wherein

[0035] The structural unit derived from a polyvalent carboxylic acid in the amorphous polyester resin contained in the black toner particles includes a structural unit derived from terephthalic acid as a main component.

[0036] <6>

[0037] The electrostatic image developing toner set according to any one of <1> to <5>, wherein

[0038] The relationship between the content (mass %) WC(K) of the crystalline polyester resin relative to the binder resin in the black toner particles and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in the magenta toner particles satisfies the following formula (WC1).

[0039] Formula (WC1) 0.90 ≤ WC(K) / WC(M) ≤ 1.10

[0040] <7>

[0041] The electrostatic image developing toner set according to any one of <1> to <6>, wherein

[0042] The relationship between the amount (mass %) of tetrahydrofuran-insoluble components in the black toner particles WT(K) and the amount (mass %) of tetrahydrofuran-insoluble components in the magenta toner particles WT(M) is 10% by mass or more and 40% by mass or less, and satisfies the following formula (WT1).

[0043] Formula (WT1): WT(K)>WT(M)

[0044] <8>

[0045] The electrostatic image developing toner set according to <7>, wherein

[0046] The relationship between the amount (mass %) WT(K) of the tetrahydrofuran-insoluble component in the black toner particles and the amount (mass %) WT(M) of the tetrahydrofuran-insoluble component in the magenta toner particles satisfies the following formula (WT2).

[0047] Formula (WT2): 2≤WT(K)-WT(M)≤10

[0048] <9>

[0049] The electrostatic image developing toner set according to <7> or <8>, wherein

[0050] The tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles contains a resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower.

[0051] <10>

[0052] The electrostatic image developing toner set according to <9>, wherein

[0053] The resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower is a styrene-(meth)acrylic acid copolymer.

[0054] <11>

[0055] The electrostatic image developing toner set according to any one of <1> to <10>, wherein

[0056] The black toner and the magenta toner have a peak that reaches a maximum in the range of 50° C. to 70° C. during the second temperature increase in thermal analysis measurement using differential scanning calorimetry (DSC).

[0057] <12>

[0058] An electrostatic image developer set comprising:

[0059] A first electrostatic image developer comprising the black toner of any one of <1> to <11> for developing an electrostatic image; and

[0060] A second electrostatic image developer includes the magenta toner in the electrostatic image developing toner set described in any one of <1> to <11>.

[0061] <13>

[0062] A toner cartridge assembly comprising:

[0063] a first toner cartridge containing the black toner of the electrostatic image developing toner set described in any one of <1> to <11>; and

[0064] The second toner cartridge contains the magenta toner of the electrostatic image developing toner set described in any one of <1> to <11>.

[0065] The toner cartridge assembly is detachable from the image forming apparatus.

[0066] <14>

[0067] A process cartridge comprising:

[0068] a first developing device containing the first electrostatic image developer of the electrostatic image developer set described in <12>; and

[0069] The second developing device contains the second electrostatic image developer in the electrostatic image developer set described in <12>.

[0070] The process cartridge is attachable to and detachable from the image forming apparatus.

[0071] <15>

[0072] An image forming apparatus comprising:

[0073] a first image forming unit that forms a black image based on the black toner in the electrostatic image developing toner set described in any one of <1> to <11>;

[0074] a second image forming unit for forming a magenta image based on the magenta toner in the electrostatic image developing toner set described in any one of <1> to <11>;

[0075] a transfer device for transferring the black image and the magenta image to a recording medium; and

[0076] The fixing device fixes the black image and the magenta image on the recording medium.

[0077] <16>

[0078] An image forming method comprising:

[0079] a first image forming step of forming a black image based on the black toner in the electrostatic image developing toner set described in any one of <1> to <11>;

[0080] a second image forming step of forming a magenta image based on the magenta toner in the electrostatic image developing toner set according to any one of <1> to <11>;

[0081] a transfer step of transferring the black image and the magenta image to a recording medium; and

[0082] The fixing step fixes the black image and the magenta image on the recording medium.

[0083] Effects of the Invention

[0084] According to the invention according to <1>, there is provided a toner set for electrostatic image development, wherein the toner comprises black toner particles containing a binder resin and a black colorant and magenta toner particles containing a binder resin and a magenta colorant, the binder resins of the black toner particles and the magenta toner particles comprising an amorphous polyester resin and a crystalline polyester resin, and the content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less. In the case where the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the black toner particles relative to the structural units derived from the polycarboxylic acid and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles does not satisfy formula (P1), low-temperature fixing ability can be ensured and unevenness in glossiness of black and magenta images generated when exposed to the outdoors can be suppressed.

[0085] According to the invention according to <2>, there is provided a toner set for electrostatic image development, which is capable of ensuring low-temperature fixing ability and suppressing unevenness in glossiness of black and magenta images caused when exposed to the outdoors, compared to a case where the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the magenta toner particles does not satisfy formula (P2).

[0086] According to the invention according to <3>, there is provided a toner set for electrostatic image development, wherein, compared to a case where the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid is less than 11 mass % or exceeds 80 mass %, the toner set ensures low-temperature fixing performance and suppresses uneven glossiness of black and magenta images that occurs when exposed to the outdoors.

[0087] According to the invention according to <4>, there is provided a toner set for electrostatic image development, wherein, compared to a case where the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid is less than 15 mass % or exceeds 50 mass %, the toner set ensures low-temperature fixing performance and suppresses uneven glossiness of black and magenta images that occurs when exposed to the outdoors.

[0088] According to the invention according to <5>, there is provided a toner set for electrostatic image development, which, compared to a case where the structural unit derived from a polycarboxylic acid in the amorphous polyester resin contained in the black toner particles does not contain terephthalic acid, ensures low-temperature fixing ability and suppresses unevenness in glossiness of black and magenta images that occurs when exposed to the outdoors.

[0089] According to the invention according to <6>, there is provided a toner set for electrostatic image development, which ensures low-temperature fixing ability and suppresses uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case in which the relationship between the content (mass %) WC(K) of the crystalline polyester resin relative to the binder resin in black toner particles and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in magenta toner particles does not satisfy the formula (WC1).

[0090] According to the invention according to <7>, there is provided a toner set for electrostatic image development, wherein low-temperature fixing ability is ensured and uneven glossiness of black and magenta images caused when exposed to the outdoors is suppressed, compared to the case where the relationship between the amount (mass %) of tetrahydrofuran-insoluble components in black toner particles (WT(K)) and the amount (mass %) of tetrahydrofuran-insoluble components in magenta toner particles (WT(M)) is less than 10% by mass or exceeds 40% by mass, or the relationship does not satisfy formula (WT1).

[0091] According to the invention according to <8>, there is provided a toner set for electrostatic image development, which is capable of ensuring low-temperature fixing ability and suppressing unevenness in glossiness of black and magenta images caused when exposed to the outdoors, compared to a case where the relationship between the amount (mass %) of tetrahydrofuran-insoluble components in black toner particles (WT(K)) and the amount (mass %) of tetrahydrofuran-insoluble components in magenta toner particles (WT(M)) does not satisfy equation (WT2).

[0092] According to the invention according to <9>, there is provided a toner set for electrostatic image development, which, compared to a case where the tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles contains a resin having a glass transition temperature (Tg) of less than 0°C or exceeding 30°C, ensures low-temperature fixability and suppresses uneven glossiness of black and magenta images generated when exposed to the outdoors.

[0093] According to the invention <10>, a toner set for electrostatic image development is provided that ensures low-temperature fixability and suppresses uneven glossiness of black and magenta images when exposed to the outdoors, compared to a case where the resin having a glass transition temperature Tg of 0°C or higher and 30°C or lower is styrene-butadiene rubber.

[0094] According to the invention described in <11>, a toner set for electrostatic image development is provided, which has a maximum peak in the range of less than 50°C or greater than 70°C during the second temperature increase in thermal analysis measurement based on differential scanning calorimetry (DSC) compared to black toner and magenta toner, thereby ensuring low-temperature fixability and suppressing uneven glossiness of black and magenta images that occurs when exposed to the outdoors.

[0095] According to the inventions of <12>, <13>, <14>, <15> or <16>, there is provided an electrostatic image developer set, a toner cartridge set, a process cartridge, an image forming apparatus or an image forming method, which can ensure low-temperature fixability and suppress unevenness in glossiness of black and magenta images when exposed to the outdoors, compared to a case where the following electrostatic image developing toner is used: a black toner having black toner particles containing a binder resin and a black colorant and a magenta toner having magenta toner particles containing a binder resin and a magenta colorant, wherein the binder resin of the black toner particles and the magenta toner particles contains an amorphous polymer. In a toner for developing an electrostatic image comprising an ester resin and a crystalline polyester resin, and in which the content of the crystalline polyester resin relative to the binder resin in the black toner particles and the magenta toner particles is 7% by mass or more and 40% by mass or less, the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles does not satisfy formula (P1). BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0097] Figure 1 FIG. 1 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0098] Figure 2 This is a schematic structural diagram showing an example of a process cartridge that is attached to and detached from the image forming apparatus according to the present embodiment.

[0099] Explanation of symbols

[0100] 1Y, 1M, 1C, 1K - photoreceptor (an example of an image holding member), 2Y, 2M, 2C, 2K - charging roller (an example of a charging device), 3 - exposure device (an example of an electrostatic image forming device), 3Y, 3M, 3C, 3K - laser beam, 4Y, 4M, 4C, 4K - developing device (an example of a developing device), 5Y, 5M, 5C, 5K - primary transfer roller (an example of a primary transfer device), 6Y, 6M, 6C, 6K - photoreceptor cleaning device (an example of a cleaning device), 8Y, 8M, 8C, 8K - toner cartridge, 10Y, 10M, 10C, 10K - image forming unit, 20 - intermediate transfer belt (an example of an intermediate transfer member), 22 - drive roller, 24 - backup roller, 26 - Secondary transfer roller (an example of a secondary transfer device), 28-fixing device (an example of a fixing device), 30-intermediate transfer body cleaning device, 107-photoreceptor (an example of an image holding body), 108-charging roller (an example of a charging device), 109-exposure device (an example of an electrostatic image forming device), 111-developing device (an example of a developing device), 112-transfer device (an example of a transfer device), 113-photoreceptor cleaning device (an example of a cleaning device), 115-fixing device (an example of a fixing device), 116-mounting guide, 118-opening portion for exposure, 117-housing, 200-processing box, 300-recording paper (an example of a recording medium), P-recording paper (an example of a recording medium). DETAILED DESCRIPTION

[0101] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples illustrate the embodiment and do not limit the scope of the invention.

[0102] In the numerical ranges described in stages in this specification, the upper limit or lower limit described in one numerical range may be replaced by the upper limit or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may also be replaced by the value shown in the Examples.

[0103] In this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid.

[0104] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended purpose of the process can be achieved.

[0105] Each component may contain multiple corresponding substances.

[0106] When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, the amount refers to the total amount of the multiple substances present in the composition.

[0107] [Toner Set for Electrostatic Image Development]

[0108] The electrostatic image developing toner set (hereinafter also referred to as "toner set") according to this embodiment includes: a black toner having black toner particles containing a binder resin and a black colorant; and a magenta toner having magenta toner particles containing a binder resin and a magenta colorant.

[0109] The binder resin contained in the black toner particles and the magenta toner particles includes an amorphous polyester resin and a crystalline polyester resin.

[0110] The content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less.

[0111] The amorphous polyester resin contained in the black toner particles and the magenta toner particles is composed of a structural unit derived from a polyvalent carboxylic acid and a structural unit derived from a polyol.

[0112] Moreover, the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles (i.e., all the amorphous polyester resins contained in the toner particles) and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles (i.e., all the amorphous polyester resins contained in the toner particles) satisfies the formula (P1) described later.

[0113] With the above-described configuration, the toner set according to this embodiment can ensure low-temperature fixability and suppress uneven glossiness of black and magenta images that occurs when exposed to the outdoors. The reason for this is presumably as follows.

[0114] Conventionally, there is known a toner using a combination of an amorphous polyester resin and a crystalline polyester resin in order to achieve both low-temperature fixing ability and heat storability.

[0115] However, in toners that use both amorphous and crystalline polyester resins, the crystalline polyester resin readily undergoes molecular motion at high temperatures. Therefore, when an image is exposed outdoors (i.e., in direct sunlight), the outermost surface of the image may soften due to the heat, causing a slight increase in image gloss.

[0116] In the case of a monochrome image, the entire image becomes hotter in a nearly uniform state, and the glossiness also rises in a nearly uniform state. Therefore, the unevenness of the glossiness of the image is small, and the image is less likely to feel uncomfortable.

[0117] On the other hand, in the case of a multi-color image consisting of a black image and a color image other than black, the black image absorbs light more readily on its surface, leading to a higher temperature than the color images other than black. Consequently, the glossiness of the black image varies more significantly than that of the color images other than black. This can sometimes result in high-gloss areas and low-gloss areas within the same image, causing uneven glossiness.

[0118] In particular, under visible light, the magenta image absorbs less light than other colors, so the difference in glossiness between the magenta image and the black image becomes larger, and the unevenness in glossiness is easily visually recognized.

[0119] In contrast, in the toner set involved in this embodiment, the structure is set as follows: the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles satisfies the formula (P1) described later.

[0120] That is, the mass ratio of the structural unit derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles is increased compared to the amorphous polyester resin contained in the black toner particles.

[0121] When the main chain of the amorphous polyester resin contains a structural unit derived from a phthalic acid other than terephthalic acid, a bent portion will exist in the main chain, and thus gaps will be easily formed between molecular chains.

[0122] In toner particles containing an amorphous polyester resin and a crystalline polyester resin, if voids exist in the amorphous polyester resin, the crystalline polyester resin may intrude into the voids of the amorphous polyester resin due to heating and cooling during toner fixing.

[0123] In this manner, the abundance ratio of the crystalline polyester resin on the surface of an image formed by applying a toner using an amorphous polyester resin having a large number of structural units derived from phthalic acid other than terephthalic acid becomes high.

[0124] That is, if the configuration is such that the mass ratio of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles is increased compared to the amorphous polyester resin contained in the black toner particles, the presence ratio of the crystalline polyester resin on the image surface of the magenta image based on the magenta toner will be greater than that of the black image based on the black toner.

[0125] Therefore, compared to a black image using a black toner, a magenta image using a magenta toner exhibits increased molecular motion of the crystalline polyester resin on the image surface at high temperatures. Consequently, when the image surface temperature rises due to exposure to outdoor sunlight (i.e., direct sunlight), the glossiness of the magenta image using the magenta toner increases in the same manner as the glossiness of the black image using the black toner. In other words, the glossiness of the black image using the black toner is suppressed to the same extent as the glossiness of the magenta image using the magenta toner.

[0126] As a result, the difference in glossiness between the black image and the magenta image becomes smaller, and unevenness in glossiness between the black image and the magenta image can be suppressed.

[0127] Based on the above, it is inferred that the toner set according to this embodiment can ensure low-temperature fixing properties and suppress uneven glossiness of black and magenta images that occurs when exposed to the outdoors.

[0128] The toner set according to this embodiment is described in detail below. In the following description, common features of black toner or black toner particles and magenta toner or magenta toner particles are referred to simply as "toner or toner particles," or are not specifically described.

[0129] <Toner>

[0130] Each toner in the toner set according to the present embodiment (hereinafter also referred to as “toner according to the present embodiment”) has toner particles. The toner according to the present embodiment may have an external additive.

[0131] (Toner particles)

[0132] The toner particles contain an amorphous resin and a crystalline resin as a binder resin and a colorant. The toner particles may contain a colorant, a release agent, internally added crosslinked resin particles, and other additives.

[0133] Specifically, black toner particles contain an amorphous resin and a crystalline resin as a binder resin and a black colorant.

[0134] The magenta toner particles contain an amorphous resin and a crystalline resin as a binder resin, and a magenta colorant.

[0135] -Binding resin-

[0136] Suitable binder resins include amorphous polyester resins and crystalline polyester resins. The content of the crystalline polyester resin relative to the binder resin is preferably 7% by mass to 40% by mass, for example, preferably 10% by mass to 35% by mass, and more preferably 15% by mass to 30% by mass.

[0137] If the content of the crystalline polyester resin is less than 7% by mass, low-temperature fixing ability decreases.

[0138] If the content of the crystalline polyester resin exceeds 40% by mass, the glossiness of the images of each color varies excessively, and it is impossible to suppress unevenness in the glossiness of the black image and the magenta image.

[0139] The relationship between the content (mass %) WC(K) of the crystalline polyester resin relative to the binder resin in the black toner particles and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in the magenta toner particles preferably satisfies the following formula (WC1), more preferably satisfies the following formula (WC2), and even more preferably satisfies the following formula (WC3).

[0140] When the following conditions (WC1), (WC2), or (WC3) are satisfied, the difference in the amount of crystalline polyester resin between the black toner particles and the magenta toner particles is reduced. When exposed to outdoor conditions, the difference in gloss between the black image and the magenta image after glossiness is increased is reduced, making it possible to easily suppress unevenness in the black and magenta images. Furthermore, the difference in gloss between the black and magenta images under indoor high-temperature and high-humidity conditions is reduced, making it possible to easily suppress unevenness in the black and magenta images.

[0141] Formula (WC1) 0.90 ≤ WC(K) / WC(M) ≤ 1.10

[0142] Formula (WC2) 0.93 ≤ WC(K) / WC(M) ≤ 1.07

[0143] Formula (WC3) 0.96 ≤ WC(K) / WC(M) ≤ 1.04

[0144] The "crystallinity" of a resin refers to the presence of a clear endothermic peak in differential scanning calorimetry (DSC) rather than a step-like change in endothermic value. Specifically, it refers to the half-width of the endothermic peak being within 10°C when measured at a heating rate of 10°C / min.

[0145] On the other hand, the "amorphous nature" of a resin means that the half-value width exceeds 10° C., a step-like change in endothermic value is observed, or a clear endothermic peak cannot be confirmed.

[0146] The amorphous polyester resin will be described.

[0147] The amorphous polyester resin is a condensation product of a polycarboxylic acid and a polyol, that is, an amorphous polyester resin having a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol.

[0148] Furthermore, the amorphous polyester resin includes an amorphous polyester resin having a structural unit derived from a phthalic acid other than terephthalic acid as a structural unit derived from a polyvalent carboxylic acid.

[0149] The mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin (S) to the structural units derived from polycarboxylic acid in the amorphous polyester resin contained in the black toner particles (i.e., all the amorphous polyester resins contained in the toner particles) and the mass ratio (mass %) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin (S) to the structural units derived from polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles (i.e., all the amorphous polyester resins contained in the toner particles)

[0150] The relationship between (%) and P(M) satisfies, for example, the following formula (P1), preferably the following formula (P2), and more preferably the following formula (P3).

[0151] Formula (P1): 10≤P(M)-P(K)≤40

[0152] Formula (P2): 15≤P(M)-P(K)≤35

[0153] Formula (P3): 20≤P(M)-P(K)≤30

[0154] When the "P(M)-P(K)" value is less than 10% by mass or exceeds 40% by mass, when exposed to the outdoors, the difference in glossiness between the black image and the magenta image after the glossiness is increased becomes larger, and the unevenness of the black image and the magenta image cannot be suppressed.

[0155] Here, from the viewpoint of suppressing uneven glossiness of black and magenta images, the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid contained in the magenta toner particles is, for example, preferably from 11 mass % to 80 mass %, more preferably from 15 mass % to 50 mass %, and even more preferably from 20 mass % to 35 mass %.

[0156] The structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner preferably contain, for example, structural units derived from terephthalic acid as a main component. In particular, the structural units derived from the polycarboxylic acid, excluding structural units derived from phthalic acids other than terephthalic acid, are preferably all structural units derived from terephthalic acid.

[0157] Furthermore, “the structural unit derived from the polyvalent carboxylic acid contains the structural unit derived from terephthalic acid as a main component” means that the structural unit derived from terephthalic acid contains the structural unit derived from terephthalic acid in the largest mass ratio among the structural units derived from the polyvalent carboxylic acid.

[0158] The mass ratio (mass %) of the structural unit derived from each polyvalent carboxylic acid in the amorphous polyester resin (that is, all the amorphous polyester resins contained in the toner particles) is measured as follows.

[0159] The toner is dissolved in a solvent such as tetrahydrofuran (THF) in which the binder resin is soluble to remove insoluble components, and then dried. Furthermore, the amorphous polyester resin and the crystalline resin in the binder resin are separated using a solvent in which the amorphous polyester resin is soluble and the crystalline resin is insoluble, utilizing the difference in solubility between the amorphous polyester resin and the crystalline resin in the solvent. After confirming the absence of an endothermic peak derived from the crystalline resin in the obtained amorphous polyester resin using a DSC (differential scanning calorimeter), the amorphous polyester resin is subjected to a separation process. 1 H-NMR measurement: The obtained NMR spectrum was analyzed to determine the chemical shift and the integral value ratio.

[0160] Then, based on the chemical shift and the integrated value ratio, the mass ratio (mass %) of the structural unit derived from each polyvalent carboxylic acid in the amorphous polyester resin (that is, all the amorphous polyester resins contained in the toner particles) can be determined.

[0161] Examples of phthalic acids other than terephthalic acid include substituted or unsubstituted phthalic acid and substituted or unsubstituted isophthalic acid. Examples of substituents include alkyl groups having 1 to 4 carbon atoms, ethyl groups, and sulfonic acid groups. Specific examples of phthalic acids other than terephthalic acid include unsubstituted phthalic acid, unsubstituted isophthalic acid, methylphthalic acid, methylisophthalic acid, diethyl phthalate, and 1,3-benzenedisulfonic acid.

[0162] Examples of terephthalic acid include substituted or unsubstituted terephthalic acid. Examples of substituents include alkyl groups having 1 to 4 carbon atoms, ethyl groups, and sulfonic acid groups. Specific examples of terephthalic acid include unsubstituted terephthalic acid, methylterephthalic acid, and diethyl terephthalate.

[0163] Examples of polycarboxylic acids other than phthalic acid include aliphatic dicarboxylic acids (e.g., 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 (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., naphthalene dicarboxylic acid), anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids other than phthalic acid.

[0164] Regarding polycarboxylic acids other than phthalic acid, trivalent or higher carboxylic acids having a cross-linked structure or a branched structure may be used in combination with dicarboxylic acids. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, anhydrides thereof, or lower (e.g., carbon number 1 to 5) alkyl esters thereof.

[0165] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0166] The glass transition temperature (Tg) of the amorphous polyester resin is, for example, preferably 50° C. or higher and 80° C. or lower, and more preferably 50° C. or higher and 65° C. or lower.

[0167] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, according to the "extrapolated glass transition onset temperature" method described in JIS K 7121-1987 "Plastics - Determination of Transition Temperatures".

[0168] The weight average molecular weight (Mw) of the amorphous polyester resin is, for example, preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.

[0169] The number average molecular weight (Mn) of the amorphous polyester resin is preferably, for example, 2,000 or more and 100,000 or less.

[0170] The molecular weight distribution Mw / Mn of the amorphous polyester resin is, for example, preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0171] The weight-average molecular weight and number-average molecular weight were measured by gel permeation chromatography (GPC). GPC-based molecular weight determinations were performed using a TOSOH Corporation GPC HLC-8120GPC as a measuring apparatus and a TOSOH Corporation column TSKgel SuperHM-M (15 cm) in a THF solvent. The weight-average molecular weight and number-average molecular weight were calculated using a molecular weight calibration curve prepared from the measurement results using monodisperse polystyrene standard samples.

[0172] The amorphous polyester resin is obtained by a known production method. Specifically, for example, the polymerization temperature is set to 180° C. to 230° C., and the pressure in the reaction system is reduced as needed to allow the reaction to proceed while removing water or alcohol generated during condensation.

[0173] Furthermore, if the raw monomers are insoluble or incompatible under the reaction temperature conditions, a high-boiling-point solvent may be added as a cosolvent to dissolve them. In this case, the polycondensation reaction proceeds while the cosolvent is distilled off. If a poorly miscible monomer is present, for example, the poorly miscible monomer can be pre-condensed with an acid or alcohol intended to be polycondensed with the monomer, and then polycondensed with the main component.

[0174] Here, the amorphous polyester resin may be used alone or in combination of two or more.

[0175] For example, the amorphous polyester resin preferably uses two or more amorphous polyesters having different molecular weights in combination. For example, a low molecular weight amorphous polyester resin (L-isomer) and a high molecular weight amorphous polyester resin (H-isomer) can be used in combination.

[0176] The low molecular weight form (L-form) is preferably an amorphous polyester resin having a weight average molecular weight of 5000 to 30000 as measured by GPC. If the molecular weight is less than 5000, displacement of the high temperature portion is likely to occur, while if the molecular weight is 30000 or more, gloss in the low temperature portion is less likely to appear.

[0177] The high molecular weight body (H body) is preferably an amorphous polyester resin having a polymerization average molecular weight of 25000 to 200000 as measured by GPC. A molecular weight of 200000 or more reduces glossiness in high temperature areas and reduces the increase in fixing temperature.

[0178] The acid value of the amorphous polyester resin used in combination is preferably, for example, about 5 mgKOH / g to 20 mgKOH / g for the low molecular weight form (L form) and about 5 mgKOH / g to 15 mgKOH / g for the high molecular weight form (H form).

[0179] When two or more amorphous polyester resins are used in combination, the mass proportions (mass %) P(K) and P(M) of the structural units derived from phthalic acid other than terephthalic acid may be determined by calculating the mass proportions of the structural units derived from the polycarboxylic acid relative to all the amorphous polyester resins contained in the toner particles.

[0180] The crystalline polyester resin will be described.

[0181] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. A commercially available crystalline polyester resin may be used, or a synthetic resin may be used.

[0182] Here, in order to easily form a crystal structure, the crystalline polyester resin is preferably a polycondensate of a polymerizable monomer having a linear aliphatic group, rather than a polycondensate of a polymerizable monomer having an aromatic group.

[0183] Examples of the polycarboxylic acid 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, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof.

[0184] Regarding polycarboxylic acids, trivalent or higher carboxylic acids that have a cross-linked or branched structure may be used in combination with dicarboxylic acids. Examples of trivalent carboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0185] As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.

[0186] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0187] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion with 7 to 20 carbon atoms). Examples of the aliphatic diol include ethylene glycol, 1,3-propylene glycol, 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-eicosanediol. Among these, preferred aliphatic diols include 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0188] Regarding the polyol, a trivalent or higher alcohol having a cross-linked structure or a branched structure may be used in combination with the diol. Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0189] The polyols may be used alone or in combination of two or more.

[0190] Here, regarding the polyol, for example, the content of the aliphatic diol is preferably 80 mol% or more, and more preferably 90 mol% or more.

[0191] The melting temperature of the crystalline polyester resin is, for example, preferably 50° C. or higher and 100° C. or lower, more preferably 55° C. or higher and 90° C. or lower, and further preferably 60° C. or higher and 85° C. or lower.

[0192] The melting temperature is determined based on the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Methods for determining transition temperatures of plastics” from a DSC curve obtained by differential scanning calorimetry (DSC).

[0193] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably, for example, 6,000 or more and 50,000 or less.

[0194] Similar to the amorphous polyester resin, the crystalline polyester resin can be obtained by, for example, a well-known production method.

[0195] The content of the binder resin is, for example, preferably 40 mass % to 95 mass % inclusive, more preferably 50 mass % to 90 mass % inclusive, and further preferably 60 mass % to 85 mass % inclusive, based on the entire toner particles.

[0196] -Colorant-

[0197] As the colorant, a black colorant is used for the black toner particles, and a magenta colorant is used for the magenta toner particles.

[0198] Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, and magnetite.

[0199] Examples of magenta colorants include β-naphthol pigments, azo lake pigments, quinacridone pigments, disazo pigments, benzimidazolone pigments, disazo condensation pigments, dioxazine pigments, and diketopyrrolopyrrole pigments.

[0200] Specific examples of magenta colorants include the following:

[0201] CI Pigment Red (Pigment Red) 146, 2, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 23, 31, 32, 95, 112, 114, 119, 136, 147, 148, 150, 164, 170, 184, 187, 188, 210, 212, 213, 222, 223, 238, 245, 253, 256, 258, 261, 266, 267, 268, 269 and other β-naphthol pigments;

[0202] Azo lake pigments such as CI Pigment Red 57:1, 18:1, 48:2, 48:3, 48:4, 48:5, 50:1, 51, 52:1, 52:2, 53:1, 53:2, 53:3, 58:2, 58:4, 64:1, 68, 200;

[0203] Quinacridone pigments such as CI Pigment Red 209, 122, 192, 202, 207, and CI Pigment Violet 19;

[0204] CI Pigment Red 37, 38, 41, 111, CI Pigment Orange 13, 15, 16, 34, 44 and other disazo pigments;

[0205] Benzimidazolone pigments such as CI Pigment Red 171, 175, 176, 185, 208, CI Pigment Violet 32, CI Pigment Orange 36, 60, 62, 72;

[0206] CI Pigment Red 144, 166, 214, 220, 221, 242, 248, 262, CI Pigment Orange 31 and other disazo condensation pigments;

[0207] Dioxazine pigments such as CI Pigment Violet 23 and 37;

[0208] Diketopyrrolopyrrole pigments such as CI Pigment Red 254, 255, 264, 272, and CI Pigment Orange 71 and 73.

[0209] In addition, "CI" stands for Color Index.

[0210] The coloring agents may be used alone or in combination of two or more.

[0211] The colorant may be a surface-treated colorant as needed, and may be used in combination with a dispersant. Furthermore, multiple colorants may be used in combination.

[0212] The content of the colorant is, for example, preferably 1 mass % or more and 30 mass % or less, and more preferably 3 mass % or more and 15 mass % or less, based on the total mass of the toner particles.

[0213] -Release agent-

[0214] Examples of the release agent 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. The release agent is not limited thereto.

[0215] The melting temperature of the release agent is, for example, preferably 50° C. or higher and 110° C. or lower, and more preferably 60° C. or higher and 100° C. or lower.

[0216] The melting temperature is determined based on the “melting peak temperature” described in the method for determining the melting temperature in JIS K7121-1987 “Methods for determining transition temperatures of plastics” from a DSC curve obtained by differential scanning calorimetry (DSC).

[0217] The content of the releasing agent is, for example, preferably 1 mass % or more and 20 mass % or less, and more preferably 5 mass % or more and 15 mass % or less, based on the total mass of the toner particles.

[0218] -Internally added cross-linked resin particles-

[0219] Internally added crosslinked resin particles are resin particles contained inside toner particles, and refer to resin particles having a bridge structure between specific atoms in the polymer structure of the resin particles.

[0220] The internally added crosslinked resin particles are particles that exist in the toner particles in a state of being incompatible with the binder resin, for example.

[0221] Examples of internally added crosslinked resin particles include crosslinked resin particles crosslinked by ionic bonds (i.e., ionically crosslinked resin particles) and crosslinked resin particles crosslinked by covalent bonds (i.e., covalently crosslinked resin particles). Among these, internally added crosslinked resin particles are preferably crosslinked resin particles crosslinked by covalent bonds.

[0222] The styrene-(meth)acrylic acid copolymer particles as the internally added cross-linked resin particles are particles containing, for example, 50% by mass or more of a styrene-(meth)acrylic acid copolymer as a main component, preferably 80% by mass or more, more preferably 90% by mass or more, and especially substantially all of the styrene-(meth)acrylic acid copolymer in the resin particles.

[0223] The total amount of the styrene-based monomer and the (meth)acrylic-based monomer as monomers constituting the copolymer is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more, with the remainder being the crosslinking agent described below.

[0224] Examples of the styrene-(meth)acrylic acid-based copolymer include resins obtained by polymerizing the following styrene-based monomers and (meth)acrylic acid-based monomers by radical polymerization.

[0225] Examples of the styrene-based monomer include styrene, α-methylstyrene, vinylnaphthalene, alkyl-substituted styrenes having an alkyl chain such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene, halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene. Among these, styrene and α-methylstyrene are preferred.

[0226] Examples of the (meth)acrylic acid monomer include (meth)acrylic acid, n-methyl (meth)acrylate, n-ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isoamyl (meth)acrylate, and (meth)acrylate. Examples of the present invention include pentyl (meth)acrylate, neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, tert-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-carboxyethyl (meth)acrylate, (meth)acrylonitrile, and (meth)acrylamide. Among these, for example, n-butyl (meth)acrylate and 2-carboxyethyl (meth)acrylate are preferred.

[0227] In the internally added cross-linked resin particles, examples of the cross-linking agent for cross-linking the resin include aromatic polyvinyl compounds such as divinylbenzene and divinylnaphthalene; polyvinyl esters of aromatic polycarboxylic acids such as divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesic acid, trivinyl trimesic acid, divinyl naphthalate, and divinyl biphenylcarboxylate; divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridinedicarboxylate; vinyl esters of unsaturated heterocyclic carboxylic acid compounds such as vinyl pyromucate, vinyl furancarboxylate, vinyl pyrrole-2-carboxylate, and vinyl thiophenecarboxylate; butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, octanediol diacrylate, octanediol dimethacrylate, nonanediol diacrylate, nonanediol dimethacrylate, decanediol di ...acrylate, decanediol diacrylate, decanediol dimethacrylate, decanediol diacrylate, de (Meth)acrylates of linear polyols such as glycol dimethacrylate, dodecanediol diacrylate, and dodecanediol dimethacrylate; (meth)acrylates of branched and substituted polyols such as neopentyl glycol dimethacrylate, 2-hydroxy, and 1,3-diacryloxypropane; polyethylene glycol di(meth)acrylate, polypropylene polyethylene glycol di(meth)acrylates, divinyl succinate, divinyl fumarate, vinyl maleate, and divinyl maleate , divinyl diglycolate, vinyl itaconate, divinyl itaconate, divinyl acetone dicarboxylate, divinyl glutarate, divinyl 3,3'-thiodipropionate, trans-aconitic acid divinyl ester, trans-aconitic acid trivinyl ester, divinyl adipate, divinyl pimelate, divinyl suberate, divinyl azelate, divinyl sebacate, divinyl dodecanedioate, tridecane divinyl ester and the like. The cross-linking agent may be used alone or in combination of two or more.

[0228] Among these, bifunctional alkyl acrylates having an alkylene chain with 6 or more carbon atoms are preferably used as crosslinking agents for crosslinking the resin. That is, the internally added crosslinked resin particles preferably have bifunctional alkyl acrylates as structural units, and the alkylene chain in the bifunctional alkyl acrylate has 6 or more carbon atoms.

[0229] By using internally added crosslinked resin particles having a bifunctional alkyl acrylate as a structural unit and an alkylene chain having 6 or more carbon atoms, a toner can be easily obtained that exhibits appropriate toner deformation during fixing and exhibits particularly good low-temperature fixability. While the internally added crosslinked resin particles have a high crosslink density (i.e., a short distance between crosslinks), their elasticity tends to be excessively high. In contrast, using a bifunctional acrylate having a long alkylene chain as a crosslinking agent results in a low crosslink density (i.e., a long distance between crosslinks), which can prevent the elasticity of the internally added crosslinked resin particles from becoming excessively high.

[0230] From the viewpoint of adjusting the crosslinking density within an appropriate range, the number of carbon atoms in the alkylene chain in the bifunctional alkyl acrylate is, for example, preferably 6 or more, more preferably 6 or more and 12 or less, and even more preferably 8 or more and 12 or less. More specific examples of the bifunctional alkyl acrylate include 1,6-hexanediol acrylate, 1,6-hexanediol methacrylate, 1,8-octanediol diacrylate, 1,8-octanediol dimethacrylate, 1,9-nonanediol diacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol diacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol diacrylate, and 1,12-dodecanediol dimethacrylate. Among them, 1,10-decanediol diacrylate and 1,10-decanediol dimethacrylate are preferred.

[0231] As another crosslinking agent, for example, 2-carboxyethyl acrylate can be mentioned, and it is preferable to use at least one of the above-mentioned bifunctional alkyl acrylate and 2-carboxyethyl acrylate.

[0232] In addition, the fixing properties of the styrene-(meth)acrylic acid copolymer particles as internally added crosslinked resin particles can be controlled by adjusting the amount of crosslinking agent contained in the composition. For example, by increasing the amount of crosslinking agent contained in the composition, internally added crosslinked resin particles with good fixing properties can be easily obtained. The content of the crosslinking agent in the composition for forming the internally added crosslinked resin particles is preferably 0.3 parts by mass or more and 5.0 parts by mass or less, more preferably 0.5 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.8 parts by mass or more and 2.5 parts by mass or less, relative to 100 parts by mass of the total of the styrene monomer, the (meth)acrylic acid monomer, and the crosslinking agent.

[0233] The glass transition temperature Tg(E) of the internally added cross-linked resin particles is, for example, preferably 0° C. or higher and 30° C. or lower, and more preferably 5° C. or higher and 25° C. or lower.

[0234] The glass transition temperature Tg of the internally added cross-linked resin particles is determined from a DSC curve obtained by differential scanning calorimetry (DSC). More specifically, it is determined according to the "extrapolated glass transition onset temperature" method described in JIS K 7121-1987, "Plastics - Determination of Transition Temperatures."

[0235] Alternatively, the internally added crosslinked resin particles can be extracted from the toner by dissolving the toner in a solvent such as tetrahydrofuran (THF) in which the binder resin is soluble, recovering the insoluble portion, and then drying the toner.

[0236] In the internally added cross-linked resin particles composed of a styrene-(meth)acrylic acid copolymer, the Tg(E) can be adjusted by adjusting the polymerization conditions of the copolymer.

[0237] In particular, in order to obtain resin particles having a composition gradient within the internally added cross-linked resin particles and having regions with a high number of styrene units unevenly present on the surface, when manufacturing the particles by polymerization of a monomer solution containing a styrene monomer and a (meth)acrylic monomer, it is preferred that, for example, the content ratio of the styrene monomer relative to the (meth)acrylic monomer in the monomer solution be increased as the polymerization proceeds. "Increasing as the polymerization proceeds" typically means gradually increasing the content ratio of the styrene monomer in the monomer solution, but also includes operations such as gradually increasing the styrene monomer content in the additional monomer when adding additional monomer to the monomer solution in multiple batches, or gradually increasing the styrene monomer concentration in the monomer solution by increasing the amount of additional styrene monomer. For example, when preparing a styrene-(meth)acrylic copolymer by emulsion polymerization, the styrene monomer content in the emulsion can be gradually increased by adding the emulsion multiple times.

[0238] Furthermore, the progress of the reaction can be controlled by adjusting the polymerization temperature, polymerization time, the method of adding the polymerization initiator, and the like.

[0239] The content of the internally added crosslinked resin particles relative to the entire toner is, for example, preferably 2 mass % or more and 20 mass % or less, and more preferably 3 mass % or more and 15 mass % or less.

[0240] The average dispersion diameter of the internally added cross-linked resin particles is, for example, preferably 50 nm or more and 300 nm or less, and more preferably 80 nm or more and 250 nm or less.

[0241] The method for measuring the average dispersion diameter of the internally added cross-linked resin particles is as follows.

[0242] The toner particles or toner are mixed with epoxy resin and embedded to solidify the epoxy resin. The obtained solidified material is cut using an ultrathin sectioning device (Ultracut UCT manufactured by Leica) to produce a thin sheet sample having a thickness of more than 80 nm and less than 130 nm. Next, the obtained thin sheet sample is stained with ruthenium tetroxide in a desiccator at 30°C for 3 hours. Then, an SEM image of the stained thin sheet sample is obtained using an ultra-high resolution field emission scanning electron microscope (FE-SEM, manufactured by Hitachi High-Technologies Corporation, S-4800). Since the ease of staining with ruthenium tetroxide is different in the order of release agent, styrene-(meth) acrylic resin, and polyester resin, each component is identified based on the depth caused by the degree of staining. If it is difficult to distinguish the depth based on the state of the sample, the staining time is adjusted.

[0243] In addition, in the cross section of the toner particles, the domains of the colorant are smaller than the domains of the release agent and the domains of the resin particles, and therefore are divided according to their size.

[0244] In the SEM image, 30 toner cross sections with a maximum length of at least 85% of the toner particle volume average particle diameter were selected, and a total of 100 dyed internally added cross-linked resin particles (i.e., their domains) were observed. The maximum length of each domain was measured, and the maximum length was considered the domain diameter. The average equivalent circle diameter was calculated by arithmetic averaging these diameters. The obtained average equivalent circle diameter was then used as the average dispersed diameter of the internally added cross-linked resin particles.

[0245] The adjustment of the average dispersion diameter of the internally added cross-linked resin particles can be achieved, for example, by controlling the following steps: producing toner particles by agglomeration, adjusting the volume average particle size of the internally added cross-linked resin particles contained in the internally added cross-linked resin particle dispersion used during the production; preparing a plurality of internally added cross-linked resin particle dispersions having different volume average particle sizes and using them in combination.

[0246] The average shape factor SF-1 of the internally added cross-linked resin particles is preferably 130 or less, for example.

[0247] When the average shape factor SF-1 of the internally added cross-linked resin particles is within the above range, domain growth of the crystalline polyester resin is easily suppressed. As a result, transfer unevenness is easily suppressed and low-temperature fixing properties are improved.

[0248] The average shape factor SF-1 was calculated by the following formula.

[0249] SF-1=(ML / A)×(π / 4)×100

[0250] In the above formula, ML represents the absolute maximum length of the toner particle, and A represents the projected area of ​​the toner particle.

[0251] Specifically, a sample was prepared using the same method as described above for measuring the average dispersion diameter of the internally added cross-linked resin particles. Thirty toner cross-sections with a maximum length of at least 85% of the toner particle volume average particle diameter were selected for SEM imaging, and a total of 100 dyed internally added cross-linked resin particles were observed. The observed SEM images were read into the Luzex image analysis and processing system (manufactured by NIRECO CORPORATION). The maximum length and projected area of ​​the 100 particles were calculated and averaged using the above formula. This average was used as the average shape factor SF-1 of the internally added cross-linked resin particles.

[0252] -Method for producing internally added cross-linked resin particles-

[0253] As a method for producing internally added cross-linked resin particles, for example, known methods such as emulsion polymerization, melt kneading using a Banbury mixer or kneader, suspension polymerization, and spray drying can be used. However, in order to make the units derived from the styrene-based monomers unevenly present on the particle surface, emulsion polymerization is preferred.

[0254] In the method for producing internally added crosslinked resin particles, for example, it is preferred to use a styrene-based monomer and a (meth)acrylic-based monomer as monomers and polymerize them in the presence of a crosslinking agent.

[0255] In the method for producing internally added crosslinked resin particles, for example, it is preferable to carry out emulsion polymerization multiple times.

[0256] Hereinafter, the method for producing the internally added cross-linked resin particles will be described in more detail.

[0257] The method for producing internally added cross-linked resin particles preferably includes, for example:

[0258] a step of obtaining an emulsion containing a monomer, a cross-linking agent, a surfactant, and water (emulsion preparation step);

[0259] a step of polymerizing the monomers by adding a polymerization initiator to the emulsion and heating the emulsion (a first emulsion polymerization step); and

[0260] A step of polymerizing the monomer by adding an emulsion containing a monomer and a cross-linking agent to the reaction solution after the first emulsion polymerization step and heating the mixture (second emulsion polymerization step).

[0261] Furthermore, in the second emulsion polymerization step, in order to adjust the composition of the particle surface, the ratio of the styrene-based monomer to the (meth)acrylic-based monomer may be changed to prepare an emulsion, and then the emulsion may be added multiple times.

[0262] --Emulsion preparation process--

[0263] The emulsion preparation step is a step of obtaining an emulsion containing a monomer, a cross-linking agent, a surfactant, and water.

[0264] For example, it is preferred to obtain an emulsion by emulsifying a monomer, a crosslinking agent, a surfactant, and water using an emulsifier.

[0265] Examples of emulsifiers include rotary stirrers with propeller-type, anchor-type, paddle-type, or turbine-type stirring blades; static mixers such as static mixers; rotor / stator emulsifiers such as homogenizers and CERAMIX; mill-type emulsifiers with a grinding function; high-pressure emulsifiers such as a Manton-Gaulin pressure emulsifier; high-pressure nozzle-type emulsifiers that generate cavitation under high pressure; high-pressure collision-type emulsifiers such as a microfluidizer that apply shear force by causing liquids to collide with each other under high pressure; ultrasonic emulsifiers that generate cavitation using ultrasonic waves; membrane emulsifiers that emulsify through fine pores, etc.

[0266] As the monomer, for example, a styrene-based monomer and a (meth)acrylic-based monomer are preferably used.

[0267] As the cross-linking agent, the cross-linking agents already described are suitable.

[0268] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols. Nonionic surfactants can be used in combination with anionic or cationic surfactants. Among these, anionic surfactants are preferred. Surfactants can be used alone or in combination of two or more.

[0269] The emulsion may contain a chain transfer agent. As the chain transfer agent, there is no particular limitation, and compounds having a mercaptan component can be used. Specifically, for example, alkyl mercaptans such as hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan are preferred.

[0270] The mass ratio of the styrene-based monomer to the (meth)acrylic-based monomer in the emulsion (styrene-based monomer / (meth)acrylic-based monomer) is preferably, for example, 0.2 or more and 1.1 or less.

[0271] Furthermore, the content of the cross-linking agent relative to the entire emulsion is preferably, for example, 0.5% by mass or more and 3% by mass or less.

[0272] --First emulsion polymerization step--

[0273] The first emulsion polymerization step is a step of polymerizing the monomers by adding a polymerization initiator to the emulsion and heating the emulsion.

[0274] Here, when performing polymerization, it is preferred that the emulsion (reaction solution) containing the polymerization initiator is stirred using, for example, a stirrer.

[0275] Examples of the stirrer include a rotary stirrer equipped with a propeller-type, anchor-type, paddle-type, or turbine-type stirring blade.

[0276] As the polymerization initiator, for example, ammonium persulfate is preferably used.

[0277] --Second emulsion polymerization step--

[0278] The second emulsion polymerization step is a step of polymerizing the monomers by adding an emulsion containing the monomers to the reaction solution after the first emulsion polymerization step and heating the mixture.

[0279] During the polymerization, for example, the reaction solution is preferably stirred in the same manner as in the first emulsion polymerization step.

[0280] In this step, the ratio of the styrene-based monomer to the (meth)acrylic-based monomer in the emulsion containing monomers may be changed, and the emulsion may be added in multiple batches.

[0281] The emulsion containing the monomer is preferably obtained by emulsifying the monomer, a surfactant, and water using an emulsifier, for example.

[0282] -Other additives-

[0283] Examples of other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as internal additives.

[0284] - Characteristics of toner particles, etc. -

[0285] The relationship between the amount (mass %) of tetrahydrofuran-insoluble components in black toner particles WT(K) and the amount (mass %) of tetrahydrofuran-insoluble components in magenta toner particles WT(M) is preferably, for example, 15% by mass or more and 40% by mass or less, and satisfies the following formula (WT1).

[0286] The relationship between the tetrahydrofuran-insoluble content (mass %) WT(K) in the black toner particles and the tetrahydrofuran-insoluble content (mass %) WT(M) in the magenta toner particles preferably satisfies the following formula (WT2), for example.

[0287] Formula (WT1): WT(K)>WT(M)

[0288] Formula (WT2): 2≤WT(K)-WT(M)≤10

[0289] If the THF-insoluble content (mass %) in the black and magenta toner particles is 10% to 40% by mass, respectively, and the relationship between the THF-insoluble content (mass %) WT(K) in the black toner particles and the THF-insoluble content (mass %) WT(M) in the magenta toner particles satisfies the aforementioned relationship, the glossiness of the black image is less likely to increase when exposed to outdoor light, while the glossiness of the magenta image is more likely to increase. As a result, uneven glossiness between the black and magenta images can be easily suppressed. This is because the THF-insoluble content is believed to suppress the appearance of crystalline polyester resin on the image surface in black images produced with the black toner, compared to magenta images produced with the magenta toner.

[0290] The amount (mass %) of the tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles is, for example, more preferably 15 mass % or more and 35 mass % or less, and further preferably 18 mass % or more and 30 mass % or less.

[0291] The difference between the amount (mass %) WT(K) of the tetrahydrofuran-insoluble component in the black toner particles and the amount (mass %) WT(M) of the tetrahydrofuran-insoluble component in the magenta toner particles ("WT(K)-WT(M)" value) is, for example, more preferably 2 or more and 10 or less, and further preferably 3 or more and 8 or less.

[0292] The tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles preferably contains a resin having a glass transition temperature Tg of, for example, 0° C. to 30° C. (for example, preferably 5° C. to 30° C.).

[0293] The resin having a glass transition temperature Tg of 0° C. to 30° C. is preferably a styrene-(meth)acrylic acid copolymer. For example, crosslinked styrene-(meth)acrylic acid copolymers such as internally added crosslinked resin particles in toner particles correspond to styrene-(meth)acrylic acid copolymers.

[0294] When a resin having a glass transition temperature (Tg) of 0°C to 30°C (in particular, a styrene-(meth)acrylic acid copolymer) is included in the tetrahydrofuran-insoluble component, uneven glossiness of black and magenta images can be easily suppressed. This is because the presence of a resin having a glass transition temperature (Tg) of 0°C to 30°C (insoluble in tetrahydrofuran) is believed to suppress the appearance of crystalline polyester resin on the image surface in black images produced with a black toner, compared to magenta images produced with a magenta toner.

[0295] The method for measuring the tetrahydrofuran-insoluble content is as follows.

[0296] (1) 0.25 g of the toner is weighed, 40 mL of tetrahydrofuran is added thereto, and the mixture is mixed and stirred for 3 hours.

[0297] (2) The mixed solution obtained in (1) was then separated using a centrifugal separator at 2,000 rpm (rotation per minute) for 30 minutes.

[0298] (3) 5 mL of the supernatant obtained after centrifugation in (2) was weighed and transferred to an aluminum pan. Tetrahydrofuran was evaporated and dried in a vacuum dryer adjusted to 50°C.

[0299] (4) The tetrahydrofuran-insoluble components excluding inorganic substances were calculated using the following formula based on the difference in mass between the aluminum pan before and after drying.

[0300] THF insoluble content [%] = {0.25 - (mass of supernatant and aluminum pan) - (mass of aluminum pan after drying) × 8} / 0.25 × 100

[0301] The mass ratio of the resin having a glass transition temperature Tg of 0° C. to 30° C. in the tetrahydrofuran-insoluble component is, for example, preferably 5 mass % to 60 mass %, more preferably 10 mass % to 50 mass %.

[0302] The toner particles may be toner particles of a single-layer structure, or may be toner particles of a so-called core-shell structure composed of a core (core particle) and a coating layer (shell layer) that covers the core.

[0303] Here, the toner particles having a core-shell structure preferably include, for example, a core portion containing a binder resin and a colorant and, if necessary, other additives such as a release agent, and a coating layer containing a binder resin.

[0304] The volume average particle diameter (D50v) of the toner particles is, for example, preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0305] Various average particle sizes and various particle size distribution indices of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman Coulter) and ISOTON-II (manufactured by Beckman Coulter) as the electrolyte.

[0306] During measurement, 0.5 mg to 50 mg of a sample is added to 2 ml of a 5% aqueous solution of a surfactant (e.g., preferably sodium alkylbenzenesulfonate) as a dispersant, and this is added to 100 ml to 150 ml of the electrolyte.

[0307] The electrolyte solution containing the sample was dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a diameter of 2 μm to 60 μm was measured using a Coulter Multisizer II with a pore diameter of 100 μm. 50,000 particles were sampled.

[0308] For the particle size range (interval) divided based on the particle size distribution to be measured, the volume cumulative distribution and the number cumulative distribution are respectively drawn from the smaller diameter side, and the particle size that will become 16% of the cumulative is defined as the volume particle size D16v and the number particle size D16p, the particle size that will become 50% of the cumulative is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size that will become 84% of the cumulative is defined as the volume particle size D84v and the number particle size D84p.

[0309] Use these, by (D84v / D16v) 1 / 2 Calculate the volume particle size distribution index (GSDv) by (D84p / D16p) 1 / 2 Calculate the particle size distribution index (GSDp).

[0310] The average circularity of the toner particles is, for example, preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0311] The average circularity of the toner particles is calculated as (circle-equivalent circumference) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value measured by the following method.

[0312] First, the toner particles to be measured were collected by suction, forming a flattened flow. This flow was then momentarily stroboscoped to capture a particle image as a still image. This particle image was then analyzed using a flow particle image analyzer (FPIA-3000, manufactured by Sysmex Corporation). The average circularity was determined using a sample count of 3500.

[0313] When the toner contains an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant and then subjected to ultrasonic treatment to obtain toner particles from which the external additive has been removed.

[0314] (External additives)

[0315] Examples of external additives include inorganic particles. Examples of inorganic particles include SiO2, TiO2, Al2O3, SrTiO3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2) n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4 and other particles.

[0316] As the surface of the inorganic particles of the external additive, for example, hydrophobization treatment is preferably implemented.Hydrophobic treatment is carried out, for example, by impregnating the inorganic particles in a hydrophobization treatment agent.The hydrophobization treatment agent is not particularly limited, and for example, silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, etc. can be cited. They can be used alone or in combination of two or more.

[0317] The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic particles.

[0318] Examples of external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), melamine resin, and the like), cleaning activators (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based high molecular weight substances).

[0319] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 6.0% by mass or less, based on the toner particles.

[0320] (Toner Thermal Analysis Characteristics)

[0321] In thermal analysis using differential scanning calorimetry (DSC), the toner preferably exhibits a peak (exothermic peak) that reaches a maximum within the range of 50°C to 70°C (for example, preferably 55°C to 65°C) during the second temperature increase. This facilitates crystallization of the crystalline polyester resin in the image during temperature increase, thereby suppressing an excessive increase in the image's glossiness. Consequently, uneven glossiness between black and magenta images can be easily suppressed.

[0322] Furthermore, in order to adjust the thermal analysis characteristics of the toner to the above-mentioned characteristics, for example, the melting point or amount of the crystalline polyester resin may be adjusted. In addition, for example, a crystal nucleating agent may be added to promote crystallization.

[0323] Thermal analysis measurement using differential scanning calorimetry (DSC) is performed on the toner to be measured in accordance with ASTM D3418-8 (2008). Specifically, the measurement is performed as follows.

[0324] First, 10 mg of the toner to be measured is placed in a differential scanning calorimeter equipped with an automatic tangent processing system.

[0325] The sample was heated from room temperature (25°C) to 200°C at a heating rate of 10°C / min in a DSC-60Plus (manufactured by Shimadzu Corporation) and held at 200°C for 5 minutes to obtain a temperature increase spectrum (DSC curve) during the first heating step.

[0326] Next, the mixture was cooled to 50°C at a temperature drop rate of -10°C / min using liquid nitrogen, and maintained at 50°C for 2 hours.

[0327] Then, the sample was heated from 50°C to 200°C at a temperature increase rate of 10°C / min, and a temperature increase spectrum (DSC curve) was obtained during the second temperature increase.

[0328] In the temperature increase spectrum (DSC curve) at the second temperature increase, the maximum peak detected (ie, exothermic peak) is identified. Here, the endothermic peak means a peak with a half-value width of 15°C or less.

[0329] Then, it is determined whether the top of the maximum peak is within the range of 50° C. or higher and 70° C. or lower (for example, preferably within the range of 55° C. or higher and 65° C. or lower).

[0330] (Toner Manufacturing Method)

[0331] Next, a method for producing a toner according to this embodiment will be described.

[0332] The toner according to this embodiment is obtained by manufacturing toner particles and then adding an external additive to the toner particles.

[0333] Toner particles can be produced by any of dry methods (e.g., kneading and pulverization methods) or wet methods (e.g., coagulation, suspension polymerization, and dissolution suspension methods). The method for producing toner particles is not particularly limited to these methods, and well-known methods may also be used.

[0334] Among these, for example, it is preferable to obtain toner particles by an aggregation method.

[0335] Specifically, for example, when toner particles are produced by an aggregation method, the toner particles are produced through the following steps:

[0336] a step of mixing a first amorphous resin particle dispersion containing first amorphous resin particles as a binder resin, a crystalline resin particle dispersion containing crystalline resin particles as a binder resin, an internally added crosslinked resin particle dispersion containing internally added crosslinked resin particles, a colorant dispersion containing a colorant, and a release agent particle dispersion containing particles of a release agent (hereinafter also referred to as "release agent particles"), and aggregating the particles and the colorant in the obtained dispersion to form first aggregated particles (a first aggregated particle forming step);

[0337] After obtaining a first aggregated particle dispersion in which first aggregated particles are dispersed, second amorphous resin particles serving as a binder resin are added to the first aggregated particle dispersion to aggregate the second amorphous resin particles on surfaces of the first aggregated particles to form second aggregated particles (a second aggregated particle forming step); and

[0338] A step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and unify the second aggregated particles to form toner particles (fusing and unifying step).

[0339] Here, amorphous polyester resin particles are preferably used as the first amorphous resin particles and the second amorphous resin particles, and crystalline polyester resin particles are preferably used as the crystalline resin particles.

[0340] The present aggregation method is described as a method for producing toner particles containing a binder resin, a colorant, a release agent, and internally added crosslinked resin particles. However, the release agent and internally added crosslinked resin particles are components contained in the toner particles as needed.

[0341] Hereinafter, the details of each step will be described.

[0342] -Dispersion Preparation Steps-

[0343] First, various dispersions used in the cohesion method are prepared. Specifically, a first amorphous resin particle dispersion containing first amorphous resin particles as a binder resin, a crystalline resin particle dispersion containing crystalline resin particles, an internally added crosslinked resin particle dispersion containing internally added crosslinked resin particles, a colorant dispersion containing a colorant, a second amorphous resin particle dispersion containing second amorphous resin particles as a binder resin, and a release agent particle dispersion containing release agent particles are prepared.

[0344] In addition, in each dispersion preparation step, the first amorphous resin particles, the second amorphous resin particles, and the crystalline resin particles are referred to as “resin particles” in the description.

[0345] Here, the resin particle dispersion is prepared by, for example, dispersing the resin particles in a dispersion medium using a surfactant.

[0346] Examples of the dispersion medium used for the resin particle dispersion include aqueous media.

[0347] Examples of the aqueous medium include water such as distilled water and ion-exchanged water, and alcohols, etc. These may be used alone or in combination of two or more.

[0348] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols. Among these, anionic surfactants and cationic surfactants are particularly useful. Nonionic surfactants can be used in combination with anionic or cationic surfactants.

[0349] The surfactant may be used alone or in combination of two or more.

[0350] In a resin particle dispersion, the resin particles may be dispersed in a dispersion medium using, for example, a general dispersion method such as a rotary shearing homogenizer, a ball mill equipped with media, a sand mill, or a dyno-mill. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.

[0351] The phase inversion emulsification method refers to a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is added to convert the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase, thereby dispersing the resin into particles in the aqueous medium.

[0352] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less.

[0353] The volume average particle size of the resin particles is determined by dividing the particle size distribution obtained by measurement using a laser diffraction particle size distribution analyzer (e.g., LA-700, manufactured by HORIBA, Ltd.) into the resulting particle size ranges (intervals). The cumulative distribution is plotted toward the smaller particle size side, and the particle size at which the cumulative distribution of all particles reaches 50% is determined as the volume average particle size D50v. The volume average particle size of particles in other dispersions is also measured in the same manner.

[0354] The content of the resin particles in the resin particle dispersion is, for example, 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.

[0355] In addition, a colorant dispersion, a release agent particle dispersion, and an internally added crosslinked resin particle dispersion are also prepared in the same manner as the resin particle dispersion. Specifically, the volume average particle size of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the particle content are the same for the colorant dispersed in the colorant dispersion, the release agent particles dispersed in the release agent particle dispersion, and the internally added crosslinked resin particles dispersed in the internally added crosslinked resin particle dispersion.

[0356] -First Agglomerated Particle Formation Step-

[0357] Next, the first amorphous resin particle dispersion, the crystalline resin particle dispersion, the internally added crosslinked resin particle dispersion, the colorant dispersion, and the release agent particle dispersion are mixed.

[0358] Then, the first amorphous resin, crystalline resin particles, internally added crosslinked resin particles, colorant and release agent particles are heterogeneously aggregated in the mixed dispersion to form first aggregated particles containing the first amorphous resin, internally added crosslinked resin particles, colorant and release agent particles.

[0359] Specifically, for example, a coagulant is added to a dispersion obtained by mixing a first amorphous resin particle dispersion, a crystalline resin particle dispersion, an internally added cross-linked resin particle dispersion, a colorant dispersion, and a release agent particle dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less). After adding a dispersion stabilizer as needed, the temperature is set to a range of 20°C or more and 50°C or less, so that the particles dispersed in the mixed dispersion are agglomerated, thereby forming first agglomerated particles.

[0360] In the first condensed particle formation process, for example, the above-mentioned coagulant can be added at room temperature (for example, 25°C) while stirring the mixed dispersion using a rotary shearing homogenizer, and the pH of the mixed dispersion is adjusted to acidic (for example, pH is greater than 2 and less than 5), and the above-mentioned heating is performed after adding a dispersion stabilizer as needed.

[0361] Examples of coagulants include surfactants with opposite polarity to the surfactant used as a dispersant added to the mixed dispersion, inorganic metal salts, and divalent or higher metal complexes. In particular, when a metal complex is used as a coagulant, the amount of surfactant used is reduced, and the charging characteristics are improved.

[0362] If necessary, an additive that forms a complex or similar bond with the metal ion of the coagulant may be used. As such an additive, a chelating agent may be used.

[0363] Examples of the inorganic metal salt 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.

[0364] As the chelating agent, a water-soluble chelating agent can be used. Examples of the chelating agent include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).

[0365] The amount of the chelating agent added is preferably, for example, 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 (first amorphous resin particles, second amorphous resin particles, and internally added crosslinked resin particles).

[0366] -Second Agglomerated Particle Formation Step-

[0367] Next, after obtaining the first aggregated particle dispersion in which the first aggregated particles are dispersed, the second amorphous resin particle dispersion in which the second amorphous resin particles are dispersed is added to the first aggregated particle dispersion.

[0368] The second amorphous resin particles may be of the same kind as the first amorphous resin or may be of a different kind.

[0369] Next, in a dispersion of the first agglomerated particles and the second amorphous resin particles, the second amorphous resin particles are agglomerated on the surfaces of the first agglomerated particles. At this time, a dispersion of release agent particles may be added to agglomerate the second amorphous resin particles and the release agent particles on the surfaces of the first agglomerated particles. Specifically, for example, in the first agglomerated particle formation step, when the first agglomerated particles have reached a target particle size, the second amorphous resin particle dispersion is added to the first agglomerated particle dispersion, and the mixture is heated below the glass transition temperature of the second amorphous resin particles.

[0370] Then, by adjusting the pH of the dispersion liquid to a range of approximately 6.5 or higher and 8.5 or lower, the aggregation is stopped.

[0371] In this manner, second aggregated particles are obtained in which the second amorphous resin particles are aggregated so as to adhere to the surfaces of the first aggregated particles.

[0372] -Fusion / unification process-

[0373] Next, the second agglomerated particle dispersion in which the second agglomerated particles are dispersed is heated, for example, to a temperature above the glass transition temperature of the first and second amorphous resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the first and second amorphous resin particles) to fuse / unify the second agglomerated particles, thereby forming toner particles.

[0374] Through the above steps, toner particles can be obtained.

[0375] In the above-described aggregation and unification method, the first aggregated particles may be fused and unified to form toner particles without performing the second aggregated particle formation step. Furthermore, the second aggregated particle formation step may be repeated multiple times.

[0376] Furthermore, in the second aggregated particle forming step, a crystalline resin particle dispersion may be used, and an internally added cross-linked resin particle dispersion may also be used.

[0377] Here, after the fusion / unification step is completed, the toner particles formed in the solution are subjected to a known washing step, a solid-liquid separation step, and a drying step to obtain dry toner particles.

[0378] The washing step is not particularly limited, but from the perspective of chargeability, it is preferred to fully perform displacement washing with ion-exchanged water. Furthermore, the solid-liquid separation step is not particularly limited, but from the perspective of productivity, suction filtration, pressure filtration, etc. are preferably performed. Furthermore, the drying method is not particularly limited, but from the perspective of productivity, freeze drying, airflow drying, fluidized bed drying, vibrating fluidized bed drying, etc. are preferably performed.

[0379] The toner according to this embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. Mixing is preferably performed using, for example, a V-blender, Henschel mixer, or Lödige mixer. Furthermore, if necessary, a vibrating screen or pneumatic screen can be used to remove coarse toner particles.

[0380] <Electrostatic image developer set>

[0381] The present invention includes a first electrostatic image developer containing a black toner from the electrostatic image developing toner set according to the present embodiment, and a second electrostatic image developer containing a magenta toner from the electrostatic image developing toner set according to the present embodiment.

[0382] Each developer in the electrostatic image developer set according to the present embodiment may be a single-component developer containing only the toner in the toner set according to the present embodiment, or a two-component developer in which the toner and a carrier are mixed.

[0383] The carrier is not particularly limited, and known carriers may be used. Examples of the carrier include coated carriers in which a core material composed of magnetic powder is coated with a coating resin; magnetic powder-dispersed carriers in which magnetic powder is dispersed or blended in a matrix resin; and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin.

[0384] Furthermore, the magnetic powder dispersed carrier and the resin impregnated carrier may be a carrier in which the constituent particles of the carrier serve as a core material and the core material is coated with a coating resin.

[0385] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0386] Examples of the coating resin and matrix resin include styrene-(meth)acrylic resin; polyolefin resins such as polyethylene resin and polypropylene resin; polyvinyl or polyvinylidene resins such as polystyrene, (meth)acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; linear silicone resin composed of an organic siloxane bond or a modified product thereof; fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate; amino resins such as urea-formaldehyde resin; epoxy resin, etc.

[0387] The coating resin and the matrix resin preferably contain, for example, a (meth)acrylic resin, more preferably contain 50% by mass or more of the (meth)acrylic resin relative to the total mass of the resin, and even more preferably contain 80% by mass or more of the (meth)acrylic resin relative to the total mass of the resin.

[0388] In particular, the coating resin and the matrix resin preferably contain, for example, an alicyclic (meth)acrylic resin as the (meth)acrylic resin.

[0389] Furthermore, the coating resin and the matrix resin may contain other additives such as conductive particles.

[0390] Examples of the 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.

[0391] Here, in order to coat the surface of the core material with a coating resin, a coating method using a coating layer forming solution prepared by dissolving the coating resin and various additives added as needed in an appropriate solvent can be cited. The solvent is not particularly limited and can be selected taking into account the coating resin used, coating suitability, etc.

[0392] Specific resin coating methods include an immersion method in which the core material is immersed in a coating layer forming solution, a spraying method in which the coating layer forming solution is sprayed onto the surface of the core material, a fluidized bed method in which the coating layer forming solution is sprayed while the core material is floating using flowing air, and a kneading coating method in which the core material of the carrier and the coating layer forming solution are mixed in a kneading coater and the solvent is removed.

[0393] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is, for example, preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0394] <Image Forming Apparatus / Image Forming Method>

[0395] The image forming apparatus and image forming method according to this embodiment will be described.

[0396] The image forming device involved in this embodiment includes: a first image forming unit, which forms a black image based on the black toner in the electrostatic image developing toner group involved in this embodiment; a second image forming unit, which forms a magenta image based on the magenta toner in the electrostatic image developing toner group involved in this embodiment; a transfer device, which transfers the black image and the magenta image to a recording medium; and a fixing device, which fixes the black image and the magenta image on the recording medium.

[0397] The image forming device involved in this embodiment can be cited as having the following devices as the first or second image forming unit: an image retaining body; a charging device for charging the surface of the image retaining body; an electrostatic image forming device for forming an electrostatic image on the surface of the charged image retaining body; and a developing device for developing the electrostatic image formed on the surface of the image retaining body using an electrostatic image developer into a toner image.

[0398] The image forming device involved in this embodiment can also be a type having the following devices: an image holder; a charging device for charging the surface of the image holder; an electrostatic image forming device for forming an electrostatic image on the surface of the charged image holder; and a first and a second developing device as the first or second image forming unit, which develops the electrostatic image formed on the surface of the image holder using an electrostatic image developer into a toner image.

[0399] In the image forming device involved in this embodiment, an image forming method (the image forming method involved in this embodiment) is implemented, which includes the following steps: a first image forming step, forming a black image based on the black toner in the electrostatic image developing toner group involved in this embodiment; a second image forming step, forming a magenta image based on the magenta toner in the electrostatic image developing toner group involved in this embodiment; a transfer step, transferring the black image and the magenta image to a recording medium; and a fixing step, fixing the black image and the magenta image on the recording medium.

[0400] The image forming device involved in this embodiment is applicable to the following well-known image forming devices: a direct transfer method device that directly transfers the toner image (black image, magenta image in this embodiment) formed on the surface of the image retaining body to the recording medium; an intermediate transfer method device that transfers the toner image (black image, magenta image in this embodiment) formed on the surface of the image retaining body to the surface of the intermediate transfer body for the first time, and transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time; a device having a cleaning member that cleans the surface of the image retaining body after transferring the toner image but before charging; a device having an electrostatic elimination member that irradiates the surface of the image retaining body with electrostatic elimination light to eliminate static electricity after transferring the toner image but before charging, etc.

[0401] In the case of an intermediate transfer method device, the transfer device may, for example, have the following structure: an intermediate transfer body, on the surface of which a toner image is transferred; a primary transfer device, which transfers the toner image formed on the surface of the image retaining body to the surface of the intermediate transfer body for the primary transfer; and a secondary transfer device, which transfers the toner image transferred to the surface of the intermediate transfer body for the secondary transfer to the surface of the recording medium.

[0402] In the image forming apparatus according to the present embodiment, for example, the portion including the developing device may be a cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including a developing device that accommodates each electrostatic image developer of the electrostatic image developer set according to the present embodiment is preferably used.

[0403] Specifically, the processing box is applicable to the following processing box, which comprises: a first developing device, which accommodates the first electrostatic image developer in the electrostatic image developer group involved in this embodiment; and a second developing device, which accommodates the second electrostatic image developer in the electrostatic image developer group involved in this embodiment, and the processing box is loaded and unloaded on the image forming device.

[0404] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings will be described, and the description of the other parts will be omitted.

[0405] Figure 1 FIG. 1 is a diagram schematically showing the configuration of an image forming apparatus according to this embodiment.

[0406] Figure 1 The image forming apparatus shown in the figure includes first to fourth image forming units 10Y, 10M, 10C, and 10K of an electrophotographic method for outputting images of yellow (Y), magenta (M), cyan (C), and black (K) colors based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M,

[0407] The units 10C and 10K are arranged side by side so as to be separated from each other by a predetermined distance in the horizontal direction. In addition, these units 10Y, 10M, 10C, and 10K may be process cartridges that are attachable to and detachable from the image forming apparatus.

[0408] An intermediate transfer belt 20, serving as an intermediate transfer member, extends above each unit 10Y, 10M, 10C, and 10K in the drawing. The intermediate transfer belt 20 is wound around a drive roller 22 and a support roller 24, which are arranged to be spaced apart from each other in the left-to-right direction in the drawing, and travels from the first unit 10Y toward the fourth unit 10K. The support roller 24 is biased away from the drive roller 22 by a spring (not shown), thereby applying tension to the intermediate transfer belt 20 wound around the drive roller 22. Furthermore, an intermediate transfer member cleaning device 30 is provided on the outer circumference of the intermediate transfer belt 20, facing the drive roller 22.

[0409] In addition, the toners including the four colors of yellow, magenta, cyan and black contained in the toner cartridges 8Y, 8M, 8C and 8K are supplied to the developing devices (an example of a developing device) 4Y, 4M, 4C and 4K of each unit 10Y, 10M, 10C and 10K respectively.

[0410] The first to fourth units 10Y, 10M, 10C, and 10K have the same structure. Therefore, the first unit 10Y, which forms a yellow image and is located upstream in the direction of travel of the intermediate transfer belt, will be described as a representative unit. Components identical to those of the first unit 10Y will be designated with magenta (M), cyan (C), and black (K) instead of yellow (Y), and the description of the second to fourth units 10M, 10C, and 10K will be omitted.

[0411] The first unit 10Y includes a photoreceptor 1Y, which functions as an image holder. Sequentially arranged around the photoreceptor 1Y are: a charging roller (an example of a charging device) 2Y, which charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming device) 3, which exposes the charged surface to a laser beam 3Y based on a color-decomposed image signal to form an electrostatic image; a developing device (an example of a developing device) 4Y, which supplies charged toner to the electrostatic image to develop the electrostatic image; a primary transfer roller (an example of a primary transfer device) 5Y, which transfers the developed toner image to the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning device) 6Y, which removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0412] The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is positioned opposite the photoreceptor 1Y. Furthermore, each of the primary transfer rollers 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) for applying a primary transfer bias. Each bias power supply is controlled by a control unit (not shown) to vary the transfer bias applied to each primary transfer roller.

[0413] Next, the operation of forming a yellow image in the first unit 10Y will be described.

[0414] First, before the operation, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by the charging roller 2Y.

[0415] The photoreceptor 1Y is conductive (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 resistance of 100 Ω·cm or less). This photosensitive layer typically has a high electrical resistance (the resistance of a typical resin), but when irradiated with laser beam 3Y, the specific electrical resistance of the portion irradiated by the laser beam changes. Therefore, based on yellow image data sent from a control unit (not shown), laser beam 3Y is output via exposure device 3 to the surface of the charged photoreceptor 1Y. Laser beam 3Y irradiates the photosensitive layer on the surface of photoreceptor 1Y, forming an electrostatic image of a yellow image pattern on the surface of photoreceptor 1Y.

[0416] An electrostatic image refers to an image formed on the surface of the photoreceptor 1Y by charging, and is a so-called negative latent image. It is formed by the resistivity of the irradiated portion of the photosensitive layer being reduced by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flowing, while on the other hand, the charge on the portion not irradiated by the laser beam 3Y remains.

[0417] As the photoreceptor 1Y travels, the electrostatic image formed on the photoreceptor 1Y rotates to a predetermined developing position, where the developing device 4Y converts the electrostatic image on the photoreceptor 1Y into a visible image (developed image) as a toner image.

[0418] The developing device 4Y contains, for example, an electrostatic image developer containing at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being stirred within the developing device 4Y, resulting in a charge of the same polarity (negative) as the charge on the photoreceptor 1Y and being retained on the developer roller (an example of a developer retainer). The surface of the photoreceptor 1Y then passes through the developing device 4Y, whereupon the yellow toner electrostatically adheres to the de-electrostaticized latent image on the surface of the photoreceptor 1Y, thereby developing the latent image with the yellow toner. The photoreceptor 1Y, with the yellow toner image formed on it, continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0419] 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 roller 5Y. Electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y to the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and is controlled to, for example, +10 μA by a control unit (not shown) in the first unit 10Y.

[0420] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0421] Furthermore, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K in and after the second unit 10M is also controlled in accordance with the first unit.

[0422] In this manner, the intermediate transfer belt 20 to which the yellow toner image has been transferred by the first unit 10Y is sequentially transported through the second to fourth units 10M, 10C, and 10K, so that the toner images of the respective colors are superimposed and multi-transferred.

[0423] The intermediate transfer belt 20, to which the four-color toner images have been multiply transferred by the first through fourth units, reaches the secondary transfer section, which is comprised of the intermediate transfer belt 20, a backup roller 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roller (an example of a secondary transfer device) 26 disposed on the outer circumference of the intermediate transfer belt 20. Meanwhile, recording paper (an example of recording medium) P is fed into the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 via a feed mechanism at a predetermined timing, and a secondary transfer bias is applied to the backup roller 24. The applied transfer bias has a (-) polarity, the same as the polarity of the toner (-). Electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner images, transferring the toner images on the intermediate transfer belt 20 to the recording paper P. The secondary transfer bias is determined by the resistance detected by a resistance detection device (not shown) that detects the resistance of the secondary transfer section and is voltage-controlled.

[0424] Then, the recording paper P is fed into a pressure-contact portion (nip portion) of a pair of fixing rollers in a fixing device (an example of a fixing device) 28 , where the toner image is fixed on the recording paper P, thereby forming a fixed image.

[0425] Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copy machines, printers, etc. Examples of the recording medium include OHP sheets and the like in addition to the recording paper P.

[0426] To further improve the smoothness of the image surface after fixing, the surface of the recording paper P is preferably smooth. For example, coated paper obtained by coating the surface of plain paper with a resin or coated paper for printing can be preferably used.

[0427] The recording paper P on which the color image has been fixed is conveyed toward the discharge portion, thereby completing a series of color image forming operations.

[0428] <Process Cartridge / Toner Cartridge>

[0429] The process cartridge according to this embodiment will be described.

[0430] The processing box involved in this embodiment is a processing box that includes a developing device and is loaded and unloaded from an image forming device. The developing device accommodates the electrostatic image developer involved in this embodiment and uses the electrostatic image developer to develop the electrostatic image formed on the surface of the image holding body into a toner image.

[0431] The process cartridge according to this embodiment is not limited to the above-described structure, and may include a developing device and, if necessary, at least one other device selected from an image holder, a charging device, an electrostatic image forming device, and a transfer device.

[0432] Hereinafter, an example of the process cartridge according to the present embodiment is shown, but the present invention is not limited thereto.

[0433] Figure 2 It is a diagram schematically showing the structure of a process cartridge according to this embodiment.

[0434] Figure 2 The processing box 200 shown is constructed by, for example, integrally combining and holding a photosensitive body 107 (an example of an image holding body), a charging roller 108 (an example of a charging device) provided around the photosensitive body 107, a developing device 111 (an example of a developing device), and a photosensitive body cleaning device 113 (an example of a cleaning device) using a housing 117 having a mounting guide 116 and an opening 118 for exposure, and is made into a box.

[0435] in addition, Figure 2 109 denotes an exposure device (an example of an electrostatic image forming device), 112 denotes a transfer device (an example of a transfer device), 115 denotes a fixing device (an example of a fixing device), and 300 denotes recording paper (an example of a recording medium).

[0436] Next, the toner cartridge according to this embodiment will be described.

[0437] The toner cartridge according to the present embodiment contains each toner of the toner set according to the present embodiment and is attachable to and detachable from an image forming apparatus. The toner cartridge contains replenishing toner for supplying to a developing device provided in the image forming apparatus.

[0438] Specifically, the toner cartridge group involved in this embodiment is a toner cartridge group comprising: a first toner cartridge containing the black toner in the toner group for electrostatic image development involved in this embodiment; and a second toner cartridge containing the magenta toner in the toner group for electrostatic image development involved in this embodiment, and being loaded and unloaded in an image forming device.

[0439] in addition, Figure 1 The image forming apparatus shown has a structure in which toner cartridges 8Y, 8M, 8C, and 8K are detachably mounted. The developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to the respective developing devices (colors) via toner supply tubes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced.

[0440] Example

[0441] Hereinafter, examples will be described, but the present invention is not limited to these examples. In the following description, "parts" and "%" are all based on mass unless otherwise specified.

[0442] [Preparation of emulsion (1)]

[0443] Styrene: 48.4 parts

[0444] n-Butyl acrylate: 50.1 parts

[0445] 1,10-Decanediol diacrylate: 1.5 parts

[0446] Anionic surfactant (ELEMINOL MON-2, manufactured by Sanyo Chemical Industries, Ltd.): 1.2 parts

[0447] Ion exchange water: 98.8 parts

[0448] The above materials were placed in a mixing container equipped with a stirring device and stirred to prepare an emulsion (1).

[0449] [Preparation of internally added cross-linked resin particle dispersion (S1)]

[0450] After nitrogen substitution in a reaction vessel equipped with a stirrer and a nitrogen inlet tube, 1.1 parts of anionic surfactant (ELEMINOL MON-2) and 400 parts of ion-exchanged water were added to the reaction vessel. The reaction solution was heated in an oil bath while stirring to a temperature of 75°C. After adding 10 parts of emulsion (1), 20 parts of an aqueous ammonium persulfate solution adjusted to a concentration of 10% by mass was further added and maintained for 30 minutes.

[0451] Then, while maintaining the temperature of the reaction solution at 75° C., 190 parts of the emulsion (1) were gradually added dropwise to the reaction container using a pump over 30 minutes. Furthermore, 200 parts of the emulsion (1) were added dropwise over 30 minutes.

[0452] After the addition was completed, the mixture was maintained for 60 minutes, and then 2 parts of 10% by mass ammonium persulfate were added. After further maintenance for 3 hours, the mixture was cooled to room temperature. Then, ion exchange water was added to obtain a solid content concentration of 20% by mass to prepare an internally added crosslinked resin particle dispersion (S1).

[0453] The volume average particle size of the obtained resin particles was 165 nm, and the glass transition temperature measured by a differential scanning calorimeter was 14.5°C.

[0454] [Preparation of internally added cross-linked resin particle dispersion (S2)]

[0455] [Preparation of emulsion (2)]

[0456] Emulsion (2) was prepared in the same manner as in emulsion (1), except that the amounts of styrene and n-butyl acrylate were changed to 39.0 parts styrene and 59.5 parts n-butyl acrylate. Internally added crosslinked resin particle dispersion (S2) was prepared in the same manner as in (S1), except that this emulsion (2) was used instead of emulsion (1).

[0457] The volume average particle size of the obtained resin particles was 169 nm, and the glass transition temperature measured by a differential scanning calorimeter was -1°C.

[0458] [Preparation of internally added cross-linked resin particle dispersion (S3)]

[0459] [Preparation of emulsion (3)]

[0460] Emulsion (3) was prepared in the same manner as in emulsion (1), except that the amounts of styrene and n-butyl acrylate were changed to 57.6 parts styrene and 40.9 parts n-butyl acrylate. Internally added crosslinked resin particle dispersion (S3) was prepared in the same manner as in (S1), except that this emulsion (3) was used instead of emulsion (1).

[0461] The volume average particle size of the obtained resin particles was 166 nm, and the glass transition temperature measured by a differential scanning calorimeter was 29.6°C.

[0462] [Preparation of internally added cross-linked resin particle dispersion (S4)]

[0463] [Preparation of emulsion (4)]

[0464] Emulsion (4) was prepared in the same manner as in emulsion (1), except that the amounts of styrene and n-butyl acrylate were changed to 39.7 parts styrene and 58.8 parts n-butyl acrylate. Internally added crosslinked resin particle dispersion (S4) was prepared in the same manner as in (S1), except that this emulsion (4) was used instead of emulsion (1).

[0465] The volume average particle size of the obtained resin particles was 163 nm, and the glass transition temperature measured by a differential scanning calorimeter was 0.1°C.

[0466] [Preparation of internally added cross-linked resin particle dispersion (S5)]

[0467] [Preparation of emulsion (5)]

[0468] Emulsion (5) was prepared in the same manner as in emulsion (1), except that the amounts of styrene and n-butyl acrylate were changed to 58.6 parts styrene and 39.9 parts n-butyl acrylate. Internally added crosslinked resin particle dispersion (S5) was prepared in the same manner as in (S1), except that this emulsion (5) was used instead of emulsion (1).

[0469] The volume average particle size of the obtained resin particles was 168 nm, and the glass transition temperature measured by a differential scanning calorimeter was 31.2°C.

[0470] [Preparation of Styrene Butadiene Rubber Particles (S6)]

[0471] Styrene: 54.0 parts

[0472] Butadiene: 44.5 parts

[0473] Acrylic acid: 1.4 parts

[0474] tert-Dodecanethiol: 0.1 part

[0475] Anionic surfactant (Dowfax 2a-1 manufactured by The Dow Chemical Company): 1.2 parts

[0476] Ion exchange water: 200 parts

[0477] Potassium persulfate: 1 part

[0478] The above materials were placed in a polymerization reactor and polymerized under a nitrogen atmosphere at 50°C for 2 hours. The reaction was then continued for 3 hours to terminate the polymerization. Ion-exchanged water was added to the resulting dispersion to adjust the solid content concentration to 20% by mass, thereby obtaining a rubber particle dispersion (1).

[0479] The volume average particle size of the obtained rubber particles was 200 nm, and the glass transition temperature measured by a differential scanning calorimeter was 14.9°C.

[0480] [Preparation of Amorphous Polyester Resin Particle Dispersion (KA1)]

[0481] Terephthalic acid: 80 parts by mole

[0482] Fumaric acid: 13 mol parts

[0483] Isophthalic acid: 5 mol parts

[0484] Trimellitic anhydride: 2 mol parts

[0485] Bisphenol A propylene oxide 2 mole adduct: 20 moles

[0486] Bisphenol A propylene oxide 3 mole adduct: 80 moles

[0487] The above materials were placed in a reaction vessel equipped with a stirrer, a nitrogen inlet pipe, a temperature sensor, and a distillation column. The temperature was raised to 190°C over 1 hour, and 1.2 parts of dibutyltin oxide was added per 100 parts of the above materials. While distilling off the generated water, the temperature was raised to 240°C over 6 hours and maintained at 240°C. A dehydration condensation reaction was continued for 3 hours to obtain an amorphous polyester resin (KA1).

[0488] Amorphous polyester resin (KA1): 100 parts

[0489] Methyl ethyl ketone: 55 parts

[0490] Isopropyl alcohol: 10 parts

[0491] 10% ammonia solution: 3.3 parts

[0492] The above materials were placed in a jacketed reaction vessel equipped with a condenser, a thermometer, a dripping device, and an anchor wing, and stirred and mixed at 100 rpm in a water circulation thermostatic bath while maintaining the liquid temperature at 50°C to dissolve the amorphous polyester resin (KA1).

[0493] Next, a water circulation thermostatic bath was set at 40° C., and a total of 300 parts of ion-exchanged water kept at 40° C. was added dropwise at a rate of 3 parts / minute to perform phase inversion, thereby preparing an emulsion.

[0494] The resulting emulsion was placed in an eggplant-shaped flask and placed in an evaporator equipped with a vacuum control unit via a trap ball. The flask was heated in a 60°C hot water bath while rotating. While carefully avoiding boiling, the pressure was reduced to 7 kPa. After removing the solvent, the pressure was returned to normal and the flask was water-cooled to obtain a dispersion. Ion-exchanged water was added to the resulting dispersion to obtain an amorphous polyester resin particle dispersion (KA1) with a solids content of 20% by mass. The volume average particle size of the amorphous polyester resin particles in the amorphous polyester resin particle dispersion (KA1) was 150 nm.

[0495] [Preparation of Amorphous Polyester Resin Particle Dispersion (KA2)]

[0496] Terephthalic acid: 85 parts by mole

[0497] Fumaric acid: 13 mol parts

[0498] Trimellitic anhydride: 2 mol parts

[0499] A resin particle dispersion containing resin particles having a volume average particle size of 152 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (KA2).

[0500] [Preparation of Amorphous Polyester Resin Particle Dispersion (KA3)]

[0501] Terephthalic acid: 75 parts by mole

[0502] Fumaric acid: 13 mol parts

[0503] Isophthalic acid: 10 parts by mole

[0504] Trimellitic anhydride: 2 mol parts

[0505] A resin particle dispersion containing resin particles having a volume average particle diameter of 151 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (KA3).

[0506] [Preparation of amorphous polyester resin particle dispersion (KA4)]

[0507] Terephthalic acid: 65 parts by mole

[0508] Fumaric acid: 13 mol parts

[0509] Isophthalic acid: 20 parts by mole

[0510] Trimellitic anhydride: 2 mol parts

[0511] A resin particle dispersion containing resin particles having a volume average particle size of 155 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (KA4).

[0512] [Preparation of amorphous polyester resin particle dispersion (KA5)]

[0513] Terephthalic acid: 53.5 parts by mole

[0514] Isophthalic acid: 46.5 parts by mole

[0515] A resin particle dispersion containing resin particles having a volume average particle size of 151 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (KA5).

[0516] [Preparation of amorphous polyester resin particle dispersion (KA6)]

[0517] Terephthalic acid: 32 parts by mole

[0518] Fumaric acid: 13 mol parts

[0519] Isophthalic acid: 33 parts by mole

[0520] Trimellitic anhydride: 22 mol parts

[0521] A resin particle dispersion containing resin particles having a volume average particle size of 158 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (KA6).

[0522] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA1)]

[0523] Terephthalic acid: 55 parts by mole

[0524] Isophthalic acid: 30 parts by mole

[0525] Trimellitic anhydride: 15 mol parts

[0526] A resin particle dispersion containing resin particles having a volume average particle diameter of 155 nm was obtained by the same method as for the preparation of the amorphous polyester resin particle dispersion (KA1), except that the above-mentioned material was used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby preparing an amorphous polyester resin particle dispersion (MA1).

[0527] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA2)]

[0528] Terephthalic acid: 45 parts by mole

[0529] Isophthalic acid: 40 parts by mole

[0530] Trimellitic anhydride: 15 mol parts

[0531] A resin particle dispersion containing resin particles having a volume average particle size of 150 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA2).

[0532] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA3)]

[0533] Terephthalic acid: 65 parts by mole

[0534] Isophthalic acid: 20 parts by mole

[0535] Trimellitic anhydride: 15 mol parts

[0536] A resin particle dispersion containing resin particles having a volume average particle size of 153 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA3).

[0537] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA4)]

[0538] Terephthalic acid: 75 parts by mole

[0539] Isophthalic acid: 10 parts by mole

[0540] Trimellitic anhydride: 15 mol parts

[0541] A resin particle dispersion containing resin particles having a volume average particle size of 152 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA4).

[0542] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA5)]

[0543] Terephthalic acid: 74 parts by mole

[0544] Isophthalic acid: 11 parts by mole

[0545] Trimellitic anhydride: 15 mol parts

[0546] A resin particle dispersion containing resin particles having a volume average particle size of 158 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA5).

[0547] [Preparation of amorphous polyester resin particle dispersion (MA6)]

[0548] Terephthalic acid: 70 parts by mole

[0549] Isophthalic acid: 15 parts by mole

[0550] Trimellitic anhydride: 15 mol parts

[0551] A resin particle dispersion containing resin particles having a volume average particle size of 152 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA6).

[0552] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA7)]

[0553] Terephthalic acid: 35 parts by mole

[0554] Isophthalic acid: 50 parts by mole

[0555] Trimellitic anhydride: 15 mol parts

[0556] A resin particle dispersion containing resin particles having a volume average particle size of 154 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA7).

[0557] [Preparation of amorphous polyester resin particle dispersion (MA8)]

[0558] Terephthalic acid: 5 parts by mole

[0559] Isophthalic acid: 80 parts by mole

[0560] Trimellitic anhydride: 15 mol parts

[0561] A resin particle dispersion containing resin particles having a volume average particle size of 153 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA8).

[0562] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA9)]

[0563] Terephthalic acid: 4 parts by mole

[0564] Isophthalic acid: 81 parts by mole

[0565] Trimellitic anhydride: 15 mol parts

[0566] A resin particle dispersion containing resin particles having a volume average particle size of 155 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA9).

[0567] [Preparation of amorphous polyester resin particle dispersion (MA10)]

[0568] Terephthalic acid: 15 parts by mole

[0569] Isophthalic acid: 70 parts by mole

[0570] Trimellitic anhydride: 15 mol parts

[0571] A resin particle dispersion containing resin particles having a volume average particle size of 157 nm was obtained in the same manner as the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA10).

[0572] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA11)]

[0573] Terephthalic acid: 71 parts by mole

[0574] Isophthalic acid: 14 parts by mole

[0575] Trimellitic anhydride: 15 mol parts

[0576] A resin particle dispersion containing resin particles having a volume average particle size of 152 nm was obtained in the same manner as in the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA11).

[0577] [Preparation of Amorphous Polyester Resin Particle Dispersion (MA12)]

[0578] Terephthalic acid: 39 parts by mole

[0579] Isophthalic acid: 46 parts by mole

[0580] Trimellitic anhydride: 15 mol parts

[0581] A resin particle dispersion containing resin particles having a volume average particle size of 150 nm was obtained in the same manner as the amorphous polyester resin particle dispersion (KA1), except that the above materials were used as the acid component. Ion-exchanged water was added to this resin particle dispersion to adjust the solid content to 20% by mass, thereby producing an amorphous polyester resin particle dispersion (MA12).

[0582] [Preparation of Crystalline Polyester Resin Particle Dispersion (C1)]

[0583] 1,10-Dodecanedioic acid: 225 parts

[0584] 1,6-Hexanediol: 174 parts

[0585] The above materials were placed in a reaction vessel equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor and a distillation tower. The temperature was raised to 160°C over 1 hour, and 0.8 parts by mass of dibutyltin oxide was added. While distilling off the generated water, the temperature was raised to 180°C over 6 hours, maintained at 180°C, stirred for 5 hours, and refluxed for reaction. Then, the temperature was gradually raised to 230°C under reduced pressure (3 kPa), maintained at 230°C, and stirred for 2 hours. The reactant was then cooled. After cooling, solid-liquid separation was performed, and the solid matter was dried to obtain a crystalline polyester resin (C1). The melting point of the obtained polyester resin (C1) was 71°C.

[0586] Crystalline polyester resin (C1): 100 parts

[0587] Methyl ethyl ketone: 40 parts

[0588] Isopropyl alcohol: 30 parts

[0589] 10% ammonia solution: 4 parts

[0590] The above materials were added to a 3-liter jacketed reaction vessel (BJ-30N, manufactured by Tokyo Rikakikai Co., Ltd.) equipped with a condenser, thermometer, dripping device, and anchor fins. The resin was dissolved while stirring and mixing at 100 rpm in a water-circulating thermostatic bath maintained at 80°C. The thermostatic bath was then set to 50°C, and 400 parts of ion-exchanged water, maintained at 50°C, was added dropwise at a rate of 10 parts by mass / minute to effect phase inversion, resulting in an emulsion. 576 parts by mass of the resulting emulsion and 500 parts by mass of ion-exchanged water were placed in a 2-liter eggplant-shaped flask, which was then placed in an evaporator equipped with a vacuum control unit (manufactured by Tokyo Rikakikai Co., Ltd.) via a trap ball. The flask was heated in a 60°C hot water bath while rotating. While ensuring a boiling point, the pressure was reduced to 7 kPa, and the solvent was removed. When the solvent recovery amount reached 750 parts by mass, the pressure was returned to normal, and the eggplant-shaped flask was water-cooled to obtain a dispersion. The volume average particle size D50v of the resin particles in this dispersion was 110 nm. Ion-exchanged water was then added to obtain a crystalline polyester resin particle dispersion (C1) having a solids concentration of 20% by mass.

[0591] [Preparation of Crystalline Polyester Resin Particle Dispersion (C2)]

[0592] Suberic acid: 225 parts

[0593] 1,6-Hexanediol: 174 parts

[0594] A crystalline polyester resin (C2) was obtained in the same manner as in the crystalline polyester resin particle dispersion (C1) except that the above materials were used. The melting point was 70°C.

[0595] [Preparation of Crystalline Polyester Resin Particle Dispersion (C3)]

[0596] Tetradecanedioic acid: 225 parts

[0597] 1,10-Decanediol: 174 parts

[0598] A crystalline polyester resin (C3) was obtained in the same manner as in the crystalline polyester resin particle dispersion (C1) except that the above materials were used. The melting point was 72°C.

[0599] [Preparation of Crystalline Polyester Resin Particle Dispersion (C4)]

[0600] Suberic acid: 225 parts

[0601] 1,6-Hexanediol: 174 parts

[0602] Using the above materials, a crystalline polyester resin (C4) was obtained in the same manner as in the crystalline polyester resin particle dispersion (C1), except that stirring was performed at 180°C for 8 hours. The melting point was 73°C.

[0603] [Preparation of Crystalline Polyester Resin Particle Dispersion (C5)]

[0604] Tetradecanedioic acid: 225 parts

[0605] 1,10-Decanediol: 174 parts

[0606] Using the above materials, a crystalline polyester resin (C5) was obtained in the same manner as the crystalline polyester resin particle dispersion (C1) except that stirring was performed at 180°C for 8 hours. The melting point was 73°C.

[0607] [Preparation of Colorant Dispersion (K1)]

[0608] Carbon black (Regel 330, manufactured by Cabot Corporation): 110 parts

[0609] Anionic surfactant (NEOPELEX G-65, Kao Corporation): 6 parts

[0610] Ion exchange water: 300 parts

[0611] The above materials were mixed and dispersed for 10 minutes using a homogenizer (ULTRA TURRAX T50, manufactured by IKA). Ion-exchanged water was added to the resulting dispersion to obtain a colorant dispersion (K1) having a solids content of 20% by mass. The volume average particle size of the colorant particles in the colorant dispersion (K1) was 220 nm.

[0612] [Preparation of Colorant Dispersion (M1)]

[0613] Magenta colorant ("CI Pigment Red 122", manufactured by Zeyachem): 110 parts

[0614] Anionic surfactant (NEOPELEX G-65, Kao Corporation): 6 parts

[0615] Ion exchange water: 300 parts

[0616] The above materials were mixed and dispersed for 10 minutes using a homogenizer (ULTRA TURRAX T50, manufactured by IKA). Ion-exchanged water was added to the resulting dispersion to obtain a colorant dispersion (M1) having a solids content of 20% by mass. The volume average particle size of the colorant particles in the colorant dispersion (M1) was 220 nm.

[0617] [Preparation of Release Agent Particle Dispersion]

[0618] Fischer-Tropsch wax (SASOLWAX H1, SASOL): 100 parts

[0619] Anionic surfactant (NEOPELEX G-65): 6 parts

[0620] Ion exchange water: 300 parts

[0621] The above materials were mixed, heated to 100°C, and dispersed using a homogenizer (ULTRA TURRAX T50). Furthermore, the mixture was dispersed using a Manton-Gaulin high-pressure homogenizer (manufactured by Gaulin). Ion-exchanged water was added to the dispersion to obtain a release agent particle dispersion having a solid content of 20% by mass.

[0622] The volume average particle size of the release agent particles in the release agent particle dispersion was 230 nm.

[0623] [Preparation of Black Toner (K1)]

[0624] Amorphous polyester resin particle dispersion (KA1) (solid content 20% by mass): 68.4 parts

[0625] Internally added cross-linked resin particle dispersion (1) (solid content 20% by mass): 20 parts

[0626] Crystalline polyester resin particle dispersion (C1) (solid content 20% by mass): 29.6 parts

[0627] Colorant dispersion (K1) (solid content 20% by mass): 21 parts

[0628] Release agent particle dispersion (solid content 20% by mass): 11 parts

[0629] Anionic surfactant (ELEMINOL MON-2): 0.7 parts

[0630] Ion exchange water: 200 parts

[0631] The above materials were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer. The mixture was stirred at 150 rpm for 30 minutes while maintaining the temperature at 20°C. A 0.3N nitric acid aqueous solution was then added to adjust the pH to 5.0. A 2% aluminum sulfate aqueous solution was then added while dispersing the mixture using a homogenizer (ULTRA TURRAX T50). The temperature was then raised to 45°C at a rate of 0.4°C / min while stirring and maintained for 30 minutes.

[0632] Next, 50 parts of an amorphous polyester resin particle dispersion (KA1) was added and the mixture was maintained for 30 minutes. A 0.1N sodium hydroxide aqueous solution was then added to adjust the pH to 8.5, and the mixture was maintained for 15 minutes. The mixture was then heated to 80°C at a rate of 1°C / minute while continuously stirring and maintained at 80°C for 5 hours. The mixture was then cooled, solid-liquid separated, and the solid matter was washed with ion-exchanged water before being dried in a freeze vacuum dryer for 24 hours to obtain toner particles (K1) having a volume average particle size of 5.5 μm.

[0633] 100 parts of the toner particles (K1) and 2.0 parts of hydrophobic silica (manufactured by NIPPON AEROSIL CO., LTD.: trade name RY200) are mixed with a Henschel mixer to obtain a black toner (K1).

[0634] [Production of Black Toners (K2) to (K22)]

[0635] In the preparation of the black toner (K1), except that the types and charging amounts of the resin particle dispersions were changed as shown in Table 4, black toners (K2) to (K22) were obtained in the same manner.

[0636] The amorphous polyester resin particle dispersion added later was also changed to the amorphous polyester resin particle dispersion shown in Table 4. The amount of the amorphous polyester resin particle dispersion added later was set to 50 parts, the same as that of the black toner (K1).

[0637] [Preparation of Magenta Toner (M1)]

[0638] Amorphous polyester resin particle dispersion (MA1) (solid content 20% by mass): 76.4 parts

[0639] Internally added cross-linked resin particle dispersion (1) (solid content 20% by mass): 10 parts

[0640] Crystalline polyester resin particle dispersion (C1) (solid content 20% by mass): 31.6 parts

[0641] Colorant dispersion (M1) (solid content 20% by mass): 21 parts

[0642] Release agent particle dispersion (solid content 20% by mass): 11 parts

[0643] Anionic surfactant (ELEMINOL MON-2): 0.7 parts

[0644] Ion exchange water: 200 parts

[0645] The above materials were placed in a reaction vessel equipped with a thermometer, pH meter, and stirrer. The mixture was stirred at 150 rpm for 30 minutes while maintaining the temperature at 20°C. A 0.3N nitric acid aqueous solution was then added to adjust the pH to 5.0. A 2% aluminum sulfate aqueous solution was then added while dispersing the mixture using a homogenizer (ULTRA TURRAX T50). The temperature was then raised to 45°C at a rate of 0.4°C / min while stirring and maintained for 30 minutes.

[0646] Next, 50 parts of an amorphous polyester resin particle dispersion (MA1) was added and the mixture was maintained for 30 minutes. A 0.1N sodium hydroxide aqueous solution was then added to adjust the pH to 8.5, and the mixture was maintained for 15 minutes. The mixture was then heated to 80°C at a rate of 1°C / minute while continuously stirring and maintained at 80°C for 5 hours. The mixture was then cooled, solid-liquid separated, and the solid matter was washed with ion-exchanged water before being dried in a freeze vacuum dryer for 24 hours to obtain toner particles (M1) having a volume average particle size of 5.5 μm.

[0647] 100 parts of the toner particles (M1) and 2.0 parts of hydrophobic silica (manufactured by NIPPON AEROSIL CO., LTD.: trade name RY200) are mixed with a Henschel mixer to obtain a magenta toner (M1).

[0648] [Production of Magenta Toners (M2) to (M32)]

[0649] In the preparation of the magenta toner (M1), magenta toners (M2) to (M32) were obtained in the same manner except that the types and charging amounts of the resin particle dispersions were changed as shown in Table 4.

[0650] The amorphous polyester resin particle dispersion added later was also changed to the amorphous polyester resin particle dispersion shown in Table 4. The amount of the amorphous polyester resin particle dispersion added later was set to 50 parts, the same as that of the magenta toner (M1).

[0651] [Examples 1 to 44, Comparative Examples 1 to 6]

[0652] The combination of black toner and magenta toner shown in Table 5 is used as the toner set for each example. The following items are shown for each toner. The method for measuring the characteristics of the toner is as described above.

[0653] Content of crystalline polyester resin relative to binder resin in black toner particles (mass %) WC(K)

[0654] Content of crystalline polyester resin relative to binder resin in magenta toner particles (mass %) WC(M)

[0655] The mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles

[0656] Mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles

[0657] Mass ratio (mass %) of the structural unit derived from terephthalic acid to the structural unit derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles PT(K)

[0658] Mass ratio (mass %) PT(M) of the structural unit derived from terephthalic acid to the structural unit derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles

[0659] Component type, glass transition temperature (Tg), and amount WT (K) (mass %) of the tetrahydrofuran-insoluble component in black toner particles

[0660] Component type, glass transition temperature (Tg), and amount WT (M) (mass %) of the tetrahydrofuran-insoluble component in magenta toner particles

[0661] Maximum peak temperature obtained at the second temperature increase in thermal analysis measurement of black toner and magenta toner by differential scanning calorimetry (DSC) (indicated as the maximum peak temperature of the DSC curve in the table)

[0662] [evaluate]

[0663] (Production of Developer)

[0664] 8 parts of each toner of the toner set of each example and 92 parts of the following carrier were mixed to prepare respective developers, thereby obtaining developer sets of black and magenta developers. The obtained developer sets were used in the evaluations described below.

[0665] (Carrier Production)

[0666] Ferrite particles (average particle size 35 μm): 100 parts

[0667] Toluene: 14 parts

[0668] Styrene / methyl methacrylate copolymer (copolymer ratio 15 / 85): 3 parts

[0669] Carbon black: 0.2 parts

[0670] The above components except the ferrite particles were dispersed in a sand mill to prepare a dispersion, and the dispersion was placed in a vacuum degassing kneader together with the ferrite particles, and dried under reduced pressure while stirring to obtain a carrier.

[0671] (Low-temperature fixability)

[0672] The black toner and magenta toner of each of the prepared developer sets were respectively filled in the black developing unit and the magenta developing unit of a modified "RevoriaPress PC1120" manufactured by FUJIFILM Business Innovation Corp., which is an apparatus for image quality evaluation.

[0673] Using an image quality evaluation apparatus, a black solid image and a magenta solid image were formed on Colotech 90 paper (manufactured by Xerox Corporation) using a black toner and a magenta toner, respectively.

[0674] Whether or not cold offset (a phenomenon in which a fixed image is transferred to a fixing member due to insufficient heating of the toner) occurs in the obtained fixed image is visually confirmed and evaluated according to the following evaluation criteria.

[0675] A: No trace of transfer

[0676] B: Slight traces of transfer

[0677] C: Existence transfer

[0678] (Unevenness of image glossiness)

[0679] The black toner and magenta toner of each of the prepared developer sets were respectively filled in the black developing unit and the magenta developing unit of a modified "RevoriaPress PC1120" manufactured by FUJIFILM Business Innovation Corp., which is an apparatus for image quality evaluation.

[0680] Using an image quality evaluation apparatus, a black solid image and a magenta solid image were formed on coated paper (OK TopCoat, manufactured by Oji Paper Co., Ltd.) using a black toner and a magenta toner, respectively.

[0681] Then, each of the obtained images was left under direct sunlight for 1 month.

[0682] After standing, the glossiness of the black solid image and the magenta solid image was measured using a gloss meter GM-26D (manufactured by MURAKAMI COLOR RESEARCH LABORATORY CO., LTD.) at an incident light angle of 75 degrees. The glossiness was measured at five random locations on each solid image, and the average value was calculated.

[0683] Then, the difference between the average values ​​of glossiness of the black solid image and the magenta solid image was determined, and evaluation was performed according to the following evaluation criteria.

[0684] In addition, each of the obtained images was placed in a dark room at 55°C for 2 weeks instead of being exposed to direct sunlight. The difference in the average glossiness of the black solid image and the magenta solid image was calculated in the same manner as above and evaluated according to the following evaluation criteria.

[0685] The smaller the glossiness difference is, the less uneven glossiness there is between the black solid image and the magenta solid image (ie, glossiness unevenness). A glossiness difference of 5.0 or more is not permitted.

[0686] G0: The difference in glossiness is greater than or equal to 0 and less than or equal to 1.0

[0687] G1: The difference in glossiness is 1.1 or more and 2.0 or less

[0688] G2: The gloss difference is 2.1 or more and 3.5 or less

[0689] G3: The gloss difference is 3.6 or more and 4.9 or less

[0690] G4: Glossiness difference is 5.0 or more (NG)

[0691] [Table 1]

[0692]

[0693] [Table 2]

[0694]

[0695] [Table 3]

[0696]

[0697] [Table 4]

[0698]

[0699] [Table 5-1]

[0700]

[0701] [Table 5-2]

[0702]

[0703] [Table 5-3]

[0704]

[0705] The above results show that the toner of this example can ensure low-temperature fixability and suppress uneven glossiness of black and magenta images caused when exposed to the outdoors, compared with the toner of the comparative example.

[0706] This embodiment includes the following aspects. (1)

[0708] A toner set for developing electrostatic images, comprising:

[0709] A black toner having black toner particles containing a binder resin and a black colorant; and

[0710] A magenta toner having magenta toner particles containing a binder resin and a magenta colorant,

[0711] The binder resin contained in the black toner particles and the magenta toner particles includes an amorphous polyester resin and a crystalline polyester resin.

[0712] The content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less,

[0713] The amorphous polyester resin contained in the black toner particles and the magenta toner particles is composed of a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol.

[0714] The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles satisfies the following formula (P1).

[0715] Formula (P1): 10≤P(M)-P(K)≤40 (2)

[0717] The electrostatic image developing toner set according to (1), wherein

[0718] The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the magenta toner particles satisfies the following formula (P2).

[0719] Formula (P2): 15≤P(M)-P(K)≤35 (3)

[0721] The electrostatic image developing toner set according to (1) or (2), wherein

[0722] The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 11 mass % or more and 80 mass % or less. (4)

[0724] The electrostatic image developing toner set according to (3), wherein

[0725] The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 15 mass % or more and 50 mass % or less. (5)

[0727] The electrostatic image developing toner set according to any one of (1) to (4), wherein

[0728] The structural unit derived from a polyvalent carboxylic acid in the amorphous polyester resin contained in the black toner particles includes a structural unit derived from terephthalic acid as a main component. (6)

[0730] The electrostatic image developing toner set according to any one of (1) to (5), wherein

[0731] The relationship between the content (mass %) WC(K) of the crystalline polyester resin relative to the binder resin in the black toner particles and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in the magenta toner particles satisfies the following formula (WC1).

[0732] Formula (WC1) 0.90 ≤ WC(K) / WC(M) ≤ 1.10 (7)

[0734] The electrostatic image developing toner set according to any one of (1) to (6), wherein

[0735] The relationship between the amount (mass %) of tetrahydrofuran-insoluble components in the black toner particles WT(K) and the amount (mass %) of tetrahydrofuran-insoluble components in the magenta toner particles WT(M) is 10% by mass or more and 40% by mass or less, and satisfies the following formula (WT1).

[0736] Formula (WT1): WT(K)>WT(M) (8)

[0738] The electrostatic image developing toner set according to (7), wherein

[0739] The relationship between the amount (mass %) WT(K) of the tetrahydrofuran-insoluble component in the black toner particles and the amount (mass %) WT(M) of the tetrahydrofuran-insoluble component in the magenta toner particles satisfies the following formula (WT2).

[0740] Formula (WT2): 2≤WT(K)-WT(M)≤10 (9)

[0742] The electrostatic image developing toner set according to (7) or (8), wherein

[0743] The tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles contains a resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower. (10)

[0745] The electrostatic image developing toner set according to (9), wherein

[0746] The resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower is a styrene-(meth)acrylic acid copolymer. (11)

[0748] The electrostatic image developing toner set according to any one of (1) to (10), wherein

[0749] The black toner and the magenta toner have a peak that reaches a maximum in the range of 50° C. to 70° C. during the second temperature increase in thermal analysis measurement using differential scanning calorimetry (DSC). (12)

[0751] An electrostatic image developer set comprising:

[0752] A first electrostatic image developer comprising the black toner in the electrostatic image developing toner set described in any one of (1) to (11); and

[0753] A second electrostatic image developer includes the magenta toner in the electrostatic image developing toner set described in any one of (1) to (11). (13)

[0755] A toner cartridge assembly comprising:

[0756] a first toner cartridge containing the black toner in the electrostatic image developing toner set described in any one of (1) to (11); and

[0757] A second toner cartridge containing the magenta toner of the electrostatic image developing toner set described in any one of (1) to (11),

[0758] The toner cartridge assembly is detachable from the image forming apparatus. (14)

[0760] A process cartridge comprising:

[0761] a first developing device containing the first electrostatic image developer in the electrostatic image developer group described in (12); and

[0762] The second developing device contains the second electrostatic image developer in the electrostatic image developer group described in (12), and the process cartridge is attachable to and detachable from the image forming apparatus. (15)

[0764] An image forming apparatus comprising:

[0765] a first image forming unit that forms a black image based on the black toner in the electrostatic image developing toner set described in any one of (1) to (11);

[0766] a second image forming unit that forms a magenta image based on the magenta toner in the electrostatic image developing toner set described in any one of (1) to (11);

[0767] a transfer device for transferring the black image and the magenta image to a recording medium; and

[0768] The fixing device fixes the black image and the magenta image on the recording medium. (16)

[0770] An image forming method comprising:

[0771] a first image forming step of forming a black image based on the black toner in the electrostatic image developing toner set described in any one of (1) to (11);

[0772] a second image forming step of forming a magenta image based on the magenta toner in the electrostatic image developing toner set described in any one of (1) to (11);

[0773] a transfer step of transferring the black image and the magenta image to a recording medium; and

[0774] The fixing step fixes the black image and the magenta image on the recording medium.

[0775] The effects of the above method are as follows.

[0776] According to the invention of (1), there is provided a toner set for electrostatic image development, wherein the toner comprises black toner particles containing a binder resin and a black colorant and magenta toner particles containing a binder resin and a magenta colorant, the binder resins of the black toner particles and the magenta toner particles comprising an amorphous polyester resin and a crystalline polyester resin, and the content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less. In the case where the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the black toner particles relative to the structural units derived from the polycarboxylic acid and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the amorphous polyester resin contained in the magenta toner particles does not satisfy formula (P1), low-temperature fixing ability can be ensured and unevenness in glossiness of black and magenta images generated when exposed to the outdoors can be suppressed.

[0777] According to the invention according to (2), there is provided a toner set for electrostatic image development, which is capable of ensuring low-temperature fixing performance and suppressing unevenness in glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the magenta toner particles does not satisfy formula (P2).

[0778] According to the invention according to (3), there is provided a toner set for electrostatic image development, which, compared to a case where the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid is less than 11 mass % or exceeds 80 mass %, can ensure low-temperature fixing properties and suppress unevenness in glossiness of black and magenta images generated when exposed to the outdoors.

[0779] According to the invention according to (4), there is provided a toner set for electrostatic image development, which, compared to a case where the mass ratio (mass %) P(M) of structural units derived from phthalic acid other than terephthalic acid is less than 15 mass % or exceeds 50 mass %, ensures low-temperature fixing properties and suppresses unevenness in glossiness of black and magenta images generated when exposed to the outdoors.

[0780] According to the invention described in (5), a toner set for electrostatic image development is provided, which ensures low-temperature fixing performance and suppresses uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the structural units derived from polycarboxylic acids in the amorphous polyester resin contained in the black toner particles do not contain terephthalic acid.

[0781] According to the invention according to (6), there is provided a toner set for electrostatic image development, which is capable of ensuring low-temperature fixing performance and suppressing uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the relationship between the content (mass %) WC(K) of the crystalline polyester resin relative to the binder resin in the black toner particles and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in the magenta toner particles does not satisfy the formula (WC1).

[0782] According to the invention according to (7), there is provided a toner set for electrostatic image development, wherein low-temperature fixing property is ensured and unevenness in glossiness of black and magenta images caused when exposed to the outdoors is suppressed, compared to a case where the relationship between the amount (mass %) of tetrahydrofuran-insoluble components in black toner particles (WT(K)) and the amount (mass %) of tetrahydrofuran-insoluble components in magenta toner particles (WT(M)) is less than 10 mass % or exceeds 40 mass %, or the relationship does not satisfy the formula (WT1).

[0783] According to the invention described in (8), there is provided a toner set for electrostatic image development that is capable of ensuring low-temperature fixing properties and suppressing uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the relationship between the amount (mass %) of tetrahydrofuran-insoluble components in black toner particles (WT(K)) and the amount (mass %) of tetrahydrofuran-insoluble components in magenta toner particles (WT(M)) does not satisfy the formula (WT2).

[0784] According to the invention described in (9), there is provided a toner set for electrostatic image development, which ensures low-temperature fixability and suppresses uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the tetrahydrofuran-insoluble components in the black toner particles and the magenta toner particles contain a resin having a glass transition temperature Tg of less than 0°C or exceeding 30°C.

[0785] According to the invention described in (10), a toner set for electrostatic image development is provided that ensures low-temperature fixability and suppresses uneven glossiness of black and magenta images generated when exposed to the outdoors, compared to a case where the resin having a glass transition temperature Tg of 0°C or higher and 30°C or lower is styrene butadiene rubber.

[0786] According to the invention described in (11), a toner group for electrostatic image development is provided, which has a peak that reaches a maximum value in the range of less than 50°C or more than 70°C during the second temperature increase in comparison with black toner and magenta toner in thermal analysis measurement based on differential scanning calorimetry (DSC), thereby ensuring low-temperature fixability and suppressing uneven glossiness of black and magenta images generated when exposed to the outdoors.

[0787] According to the inventions of (12), (13), (14), (15) or (16), there is provided an electrostatic image developer group, a toner cartridge group, a process cartridge, an image forming apparatus or an image forming method, which is capable of ensuring low-temperature fixability and suppressing uneven glossiness of black images and magenta images when exposed to the outdoors, compared to a case where the following electrostatic image developing toner is applied: a black toner having black toner particles containing a binder resin and a black colorant and a magenta toner having magenta toner particles containing a binder resin and a magenta colorant, wherein the binder resin of the black toner particles and the magenta toner particles contains an amorphous polymer. In a toner for developing an electrostatic image comprising an ester resin and a crystalline polyester resin, and in which the content of the crystalline polyester resin relative to the binder resin in the black toner particles and the magenta toner particles is 7% by mass or more and 40% by mass or less, the relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles does not satisfy formula (P1).

[0788] The above-described embodiments of the present invention are provided for the purpose of illustration and explanation. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed embodiments. It is obvious that various modifications and variations are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily explain the principles of the present invention and its application. Thus, other technical personnel in this field can understand the present invention through various modifications optimized for specific uses of the assumed various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A toner set for developing an electrostatic image, comprising: A black toner having black toner particles containing a binder resin and a black colorant; and A magenta toner having magenta toner particles containing a binder resin and a magenta colorant, The binder resin contained in the black toner particles and the magenta toner particles includes an amorphous polyester resin and a crystalline polyester resin. The content of the crystalline polyester resin in the black toner particles and the magenta toner particles relative to the binder resin is 7% by mass or more and 40% by mass or less, The amorphous polyester resin contained in the black toner particles and the magenta toner particles is composed of a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyol. The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid relative to the structural units derived from the polycarboxylic acid in the amorphous polyester resin contained in the magenta toner particles satisfies the following formula (P1), Formula (P1): 10≤P(M)-P(K)≤40.

2. The electrostatic image developing toner set according to claim 1, wherein: The relationship between the mass ratio (mass %) P(K) of the structural units derived from phthalic acid other than terephthalic acid in the black toner particles and the mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid in the magenta toner particles satisfies the following formula (P2), Formula (P2): 15≤P(M)-P(K)≤35.

3. The electrostatic image developing toner set according to claim 1 or 2, wherein: The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 11 mass % or more and 80 mass % or less.

4. The electrostatic image developing toner set according to claim 3, wherein: The mass ratio (mass %) P(M) of the structural units derived from phthalic acid other than terephthalic acid is 15 mass % or more and 50 mass % or less. 5 . The electrostatic image developing toner set according to claim 1 , wherein: The structural unit derived from a polyvalent carboxylic acid in the amorphous polyester resin contained in the black toner particles includes a structural unit derived from terephthalic acid as a main component. 6 . The electrostatic image developing toner set according to claim 1 , wherein: Content (mass %) of the crystalline polyester resin relative to the binder resin in the black toner particles The relationship between WC(K) and the content (mass %) WC(M) of the crystalline polyester resin relative to the binder resin in the magenta toner particles satisfies the following formula (WC1), Formula (WC1)0.90≤WC(K) / WC(M)≤1.

10. 7 . The electrostatic image developing toner set according to claim 1 , wherein: The relationship between the amount (mass %) of tetrahydrofuran-insoluble components in the black toner particles WT(K) and the amount (mass %) of tetrahydrofuran-insoluble components in the magenta toner particles WT(M) is 10% by mass or more and 40% by mass or less, and the following formula (WT1) is satisfied: Formula (WT1): WT(K)>WT(M).

8. The electrostatic image developing toner set according to claim 7, wherein: The relationship between the amount (mass %) of tetrahydrofuran-insoluble components in the black toner particles WT(K) and the amount (mass %) of tetrahydrofuran-insoluble components in the magenta toner particles WT(M) satisfies the following formula (WT2), Formula (WT2): 2≤WT(K)-WT(M)≤10.

9. The electrostatic image developing toner set according to claim 7 or 8, wherein The tetrahydrofuran-insoluble component in the black toner particles and the magenta toner particles contains a resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower.

10. The electrostatic image developing toner set according to claim 9, wherein The resin having a glass transition temperature Tg of 0° C. or higher and 30° C. or lower is a styrene-(meth)acrylic acid copolymer.

11. The electrostatic image developing toner set according to any one of claims 1 to 10, wherein The black toner and the magenta toner have a peak that reaches a maximum in the range of 50° C. to 70° C. during the second temperature increase in thermal analysis measurement using differential scanning calorimetry (DSC).

12. An electrostatic image developer set comprising: A first electrostatic image developer comprising the black toner in the electrostatic image developing toner set according to any one of claims 1 to 11; and A second electrostatic image developer includes the magenta toner in the electrostatic image developing toner set according to any one of claims 1 to 11.

13. A toner cartridge assembly comprising: a first toner cartridge containing the black toner in the electrostatic image developing toner set according to any one of claims 1 to 11; and A second toner cartridge containing the magenta toner of the electrostatic image developing toner set according to any one of claims 1 to 11, The toner cartridge assembly is detachable from the image forming apparatus.

14. A process cartridge comprising: a first developing device containing the first electrostatic image developer of the electrostatic image developer set according to claim 12; and a second developing device containing the second electrostatic image developer of the electrostatic image developer set according to claim 12; The process cartridge is attachable to and detachable from the image forming apparatus.

15. An image forming apparatus comprising: a first image forming unit for forming a black image based on the black toner in the electrostatic image developing toner set according to any one of claims 1 to 11; a second image forming unit for forming a magenta image based on the magenta toner in the electrostatic image developing toner set according to any one of claims 1 to 11; a transfer device for transferring the black image and the magenta image to a recording medium; and The fixing device fixes the black image and the magenta image on the recording medium.

16. An image forming method comprising: a first image forming step of forming a black image based on the black toner in the electrostatic image developing toner set according to any one of claims 1 to 11; a second image forming step of forming a magenta image based on the magenta toner in the electrostatic image developing toner set according to any one of claims 1 to 11; a transfer step of transferring the black image and the magenta image onto a recording medium; and The fixing step fixes the black image and the magenta image on the recording medium.

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