Yellow toner

Abstract

To provide a yellow toner which achieves both hot-offset resistance, and scratch resistance of a printing part.SOLUTION: A yellow toner includes yellow toner particles containing binder resin and a colorant. The colorant contains C.I. pigment yellow 180 and C.I. pigment yellow 214. When A (mass%) denotes a content ratio of the C.I. pigment yellow 180, and B (mass%) denotes a content ratio of the C.I. pigment yellow 214 in the toner, 4.00≥A / B≥0.25 and 20.0≥A+B≥5.0 are satisfied. In the binder resin, an acid value is 3 mgKOH / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a yellow toner used in an electrophotographic image forming method. [Background technology]

[0002] In recent years, electrophotographic full-color copiers have become widely used and are now being applied to the printing market, where demands include compatibility with a wide range of media (paper types), high speed, high image quality, high productivity, and resistance to external forces such as rubbing and scratching after printing so that the image area does not become damaged. Patent Documents 1 and 2 propose a binder resin composition for toner that uses a crystalline polyester resin as a binder resin composition for toner that has excellent low-temperature fixing property and abrasion resistance. Also, as described in Patent Document 3, a toner that uses CI Pigment Yellow 180 as a yellow pigment is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-008816 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-189955 [Patent Document 3] Patent Publication No. 2021-18270 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there was room for improvement in the gloss (image glossiness) and gloss stability of the fixed image when printing at high speed in a high-temperature, high-humidity environment. Furthermore, among color toners, yellow toner has a weaker coloring power than other colors, which makes the image density prone to fluctuation. The present invention provides a yellow toner that simultaneously achieves good gloss images, gloss stability, image density stability, and abrasion resistance of printed portions. [Means for solving the problem]

[0005] The present invention provides a yellow toner comprising yellow toner particles containing a binder resin and a colorant, the colorant comprises CI Pigment Yellow 180 and CI Pigment Yellow 214, When the content ratio of CI Pigment Yellow 180 in the toner is A (mass%) and the content ratio of CI Pigment Yellow 214 in the toner is B (mass%), 4.00≧A / B≧0.25 20.0≧A+B≧5.0 and The binder resin in the yellow toner is characterized in that it has an acid value of 3 mgKOH / g or more. [Effects of the Invention]

[0006] The present invention can provide a yellow toner that achieves good gloss images, gloss stability, image density stability, and abrasion resistance of printed portions. DETAILED DESCRIPTION OF THE INVENTION

[0007] In the present disclosure, unless otherwise specified, the expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0008] [Features of the present invention] The present invention provides a yellow toner comprising yellow toner particles containing a binder resin and a colorant, wherein the colorant contains CI Pigment Yellow 180 and CI Pigment Yellow 214, and when a content ratio of CI Pigment Yellow 180 in the toner is A (mass%) and a content ratio of CI Pigment Yellow 214 in the toner is B (mass%), the relationships are 4.00≧A / B≧0.25 and 20.0≧A+B≧5.0, The binder resin is characterized by having an acid value of 3 mgKOH / g or more.

[0009] The following is believed to be the reason why the above toner can simultaneously achieve good gloss images, gloss stability, image density stability, and abrasion resistance of printed portions.

[0010] CI Pigment Yellow 214 usually has a plate-like shape and has a primary amide group at the end of its chemical structure, and also has a secondary amide group within its structure. When this is present in a toner resin with an acid value, a weak crosslinked structure is formed by hydrogen bonding between the carboxylic acid of the resin and the primary and secondary amide groups of CI Pigment Yellow 214.

[0011] Furthermore, the presence of CI Pigment Yellow 180 in the system generates an attractive force in a π-π stack between CI Pigment Yellow 214 and CI Pigment Yellow 180. CI Pigment Yellow 180 tends to take on a needle-like structure, and the entire system has a gentle cross-linking structure due to the van der Waals forces of the filler, which can increase the strength of the toner and the entire image.

[0012] Therefore, the interaction caused by the formation of the crosslinked structure improves the abrasion resistance of the printed area. Furthermore, because the crosslinking strength is moderate and not too hard, the toner does not harden too much during the fixing process, preventing a decrease in gloss. As a result, good gloss images and good gloss stability can be achieved.

[0013] Furthermore, even when a crystalline resin is added, the mobility of the crystalline resin is suppressed because a weak crosslinking structure is formed by hydrogen bonding between the carboxylic acid of the crystalline resin and the secondary amide of CI Pigment Yellow 214. As a result, charging stability is improved and good image density stability is obtained.

[0014] [Toner Components] Each of the components of the toner will be described below.

[0015] <Coloring agent> (CI Pigment Yellow 180) The toner particles contain CI Pigment Yellow 180. The CI Pigment Yellow 180 particles of the present invention can be a commercially available material, for example, Toner Yellow HG manufactured by Heubach Color Japan Co., Ltd.

[0016] (CI Pigment Yellow 214) The toner particles contain CI Pigment Yellow 214. As the CI Pigment Yellow 214 of the present invention, a commercially available material can be used, and an example thereof is PV Fast Yellow H9G manufactured by Heubach Color Japan Co., Ltd.

[0017] (Colorant content) When the content ratio of CI Pigment Yellow 180 in the above toner is A (mass%) and the content ratio of CI Pigment Yellow 214 is B (mass%), 4.00≧A / B≧0.25 20.0≧A+B≧5.0 is.

[0018] When A / B is greater than 4.00 or less than 0.25, it becomes difficult to form the above-mentioned appropriate crosslinked structure throughout the toner or image, and the scratch resistance of the image decreases.

[0019] Furthermore, when A+B is greater than 20.0, there is too much pigment in the system, resulting in low gloss of the image, and when A+B is less than 5, the above-mentioned crosslinked structure is difficult to form in the toner or the entire image, resulting in reduced abrasion resistance of the image.

[0020] A more preferred range is: 3.50≧A / B≧1.00 15.0≧A+B≧5.0 is.

[0021] <Binder resin> The toner particles contain a binder resin. The binder resin may contain an amorphous resin or a crystalline resin. Known polymers can be used as the binder resin, and specifically, the following polymers can be used, for example.

[0022] Examples of suitable styrene copolymers include polystyrene, poly-p-chlorostyrene, polyvinyltoluene, and other styrene and substituted styrene homopolymers; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, styrene-α-chloromethyl methacrylate copolymers, styrene-acrylonitrile copolymers, styrene-vinyl methyl ether copolymers, styrene-vinyl ethyl ether copolymers, styrene-vinyl methyl ketone copolymers, and styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, natural resin-modified phenolic resins, natural resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, and petroleum-based resins. These resins may be used alone or in combination.

[0023] Among these, polyester resins are preferred for their excellent gloss and scratch resistance. Since polyester resins contain many ester groups in their molecular chains, the primary amide groups and secondary amide groups of CI Pigment Yellow 214 interact with and adsorb to the carboxylic acid chains of the polyester resin, and then the secondary amide groups of CI Pigment Yellow 214 form hydrogen bonds with the ester groups in the polyester resin chains, resulting in a good gloss image and good scratch resistance. A condensation polymer of a polyhydric alcohol compound and a polycarboxylic acid compound is preferred.

[0024] Examples of polyhydric alcohol compounds include alkylenes of bisphenol A such as polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(3.3)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, and polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane. Examples of the resin include oxide adducts, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, hydrogenated bisphenol A, and derivatives thereof. The derivatives are not particularly limited as long as they can be obtained by condensation polymerization with a similar resin structure. For example, derivatives obtained by esterifying an alcohol component are included.

[0025] The polyhydric alcohol compound used is preferably at least one selected from the group consisting of alkylene oxide adducts of bisphenol A. The proportion of the alkylene oxide adducts of bisphenol A in the polyhydric alcohol compound is preferably 50 mol % or more and 100 mol % or less, more preferably 70 mol % or more and 100 mol % or less, and even more preferably 90 mol % or more and 100 mol % or less.

[0026] The polyhydric alcohol compound used is preferably at least one selected from the group consisting of alkylene oxide adducts of bisphenol A. The proportion of the alkylene oxide adducts of bisphenol A in the polyhydric alcohol compound is preferably 50 mol % or more and 100 mol % or less, more preferably 70 mol % or more and 100 mol % or less, and even more preferably 90 mol % or more and 100 mol % or less.

[0027] Among the polycarboxylic acid compounds, examples of trivalent or higher carboxylic acid components include trimellitic acid, trimellitic anhydride, and pyromellitic acid.

[0028] The acid value of the binder resin is 3 mgKOH / g or more. If the acid value is less than 3 mgKOH / g, there is no site for interaction between the binder resin and CI Pigment Yellow 214, and therefore the scratch resistance is not improved. The acid value of the binder resin can be adjusted by adjusting the polymerization conditions of the resin or by using a trivalent or higher carboxylic acid component as the polycarboxylic acid compound as described above.

[0029] The acid value of the binder resin is preferably 5 mgKOH / g or more and 20 mgKOH / g or less, and more preferably 7 mgKOH / g or more and 17 mgKOH / g or less, since this provides an appropriate number of bonding points between CI Pigment Yellow 214 and the binder resin.

[0030] Furthermore, the binder resin preferably contains a polyethylene terephthalate segment, and the content thereof is preferably 1% by mass or more and 20% by mass or less of the binder resin. By containing the polyethylene terephthalate segment, the polyethylene terephthalate crystal parts inside the binder resin have a structure in which they are pseudo-linked to CI Pigment Yellow 214, which moderately improves the internal cohesive force of the image and improves abrasion resistance without deteriorating image gloss, gloss stability, or image density stability.

[0031] The toner particles preferably contain 1% by mass or more and 15% by mass or less of a crystalline polyester as a binder resin, and the acid value of the crystalline polyester is preferably 3 mgKOH / g or more. By containing such a crystalline polyester, carboxylic acids of the crystalline polyester close to the crystalline portion interact with CI Pigment Yellow 214, and a structure is formed in which hard portions of the crystalline portion are linked to CI Pigment Yellow 214, thereby appropriately increasing the internal cohesive force of the image portion and improving abrasion resistance without deteriorating image gloss, gloss stability, or image density stability.

[0032] Monomers used for the crystalline polyester include polyhydric alcohols (dihydric, trihydric or higher alcohols), polycarboxylic acids (dihydric, trihydric or higher carboxylic acids), their acid anhydrides or their lower alkyl esters. The crystalline polyester is preferably a condensation polymer of a linear aliphatic polyhydric alcohol having 2 to 6 carbon atoms and a linear aliphatic polycarboxylic acid having 6 to 14 carbon atoms.

[0033] Such a portion having a repeating structure of a long alkyl portion and an ester group is prone to flow during toner production, and therefore is prone to interaction between the primary amide groups and secondary amide groups on the plate-like surface of CI Pigment Yellow 214 in the toner and the carboxylic acid of the crystalline polyester resin. As a result, a structure is likely to be formed in which the crystal portions of the crystalline polyester and CI Pigment Yellow 214 are linked, improving abrasion resistance.

[0034] The polyhydric alcohol monomer used in the crystalline polyester may be any of the following polyhydric alcohol monomers. The polyhydric alcohol monomer is not particularly limited, but is preferably a chain (more preferably a linear) aliphatic diol, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,4-butadiene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, and neopentyl glycol. Among these, linear aliphatic α,ω-diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol are particularly preferred.

[0035] Polyhydric alcohol monomers other than the above polyhydric alcohols can also be used. Among the polyhydric alcohol monomers, dihydric alcohol monomers include aromatic alcohols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A; 1,4-cyclohexanedimethanol; and the like. Furthermore, among the polyhydric alcohol monomers, trihydric or higher polyhydric alcohol monomers include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; and aliphatic alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.

[0036] The polycarboxylic acid monomers used in the crystalline polyester may include the following polycarboxylic acid monomers. While the polycarboxylic acid monomer is not particularly limited, it is preferably a chain (more preferably a linear) aliphatic dicarboxylic acid. Specific examples include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid, as well as hydrolyzed versions of these acid anhydrides or lower alkyl esters.

[0037] Among the above, a crystalline polyester monomer in which the alcohol component is ethylene glycol and the acid component is dodecanedioic acid is preferred, as this facilitates the development of the mechanism for improving the abrasion resistance described above.

[0038] <Release agent> The toner particles may contain a release agent, if necessary, to suppress the occurrence of hot offset during heat fixing of the toner. Typical examples of the release agent include low-molecular-weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, and hydrocarbon waxes.

[0039] <Charge control agent> The toner particles may contain a charge control agent as needed. By incorporating a charge control agent, the charging characteristics can be stabilized and the amount of triboelectric charge can be optimally controlled according to the development system. As the charge control agent, known agents can be used, but particularly, metal compounds of aromatic carboxylic acids are preferred because they are colorless, have a high charging speed of the toner, and can stably maintain a constant amount of charge.

[0040] Examples of negative charge control agents include metal salicylate compounds, metal naphthoate compounds, metal dicarboxylate compounds, polymeric compounds having sulfonic acid or carboxylic acid on the side chain, polymeric compounds having sulfonate salts or sulfonate esters on the side chain, polymeric compounds having carboxylate salts or carboxylate esters on the side chain, boron compounds, urea compounds, silicon compounds, and calixarenes.

[0041] The charge control agent may be added internally or externally to the toner particles. The content of the charge control agent is preferably 0.2 parts by mass or more and 10.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0042] <External additives> External additives may be added to the toner particles as needed. For example, inorganic fine particles such as silica, alumina, titania, and calcium carbonate, or resin fine particles such as vinyl resin, polyester resin, and silicone resin may be added by applying shear force in a dry state. These inorganic fine particles and resin fine particles function as external additives such as flow aids and cleaning aids. The content of the external additive is preferably 1.0 parts by mass or more and 10.0 parts by mass or less, more preferably 2.0 parts by mass or more and 5.0 parts by mass or less, per 100 parts by mass of the toner particles.

[0043] [Toner manufacturing method] The method for producing the toner is not particularly limited, and known methods such as an emulsion aggregation method, a kneading-pulverization method, and a suspension polymerization method can be used, but the kneading-pulverization method is preferred from the viewpoint of efficiently promoting the interaction between the carboxylic acid of the binder resin and CI Pigment Yellow 214. The kneading-pulverization method will be described below.

[0044] First, predetermined amounts of materials constituting the toner particles, such as binder resin and other components such as CI Pigment Yellow 214, CI Pigment Yellow 180, crystalline resin, and release agent, are weighed, blended, and mixed. Examples of mixing devices include a double cone mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.).

[0045] Next, the mixed materials are melt-kneaded. In the melt-kneading step, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, but a single-screw or twin-screw extruder is preferred because of its advantage of allowing continuous production. The melt-kneading temperature is preferably about 100 to 200°C.

[0046] Here, with regard to CI Pigment Yellow 214 and CI Pigment Yellow 180, a masterbatch may be produced in advance by kneading only the binder resin with CI Pigment Yellow 214 or CI Pigment Yellow 180 before melting and kneading the materials that make up the toner particles. By using a masterbatch, there are more opportunities to promote the interaction between the resin and CI Pigment Yellow 214, which results in easier improvement of the abrasion resistance of the toner.

[0047] Examples of kneading devices that can be used include a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by KCK Corporation), a Co-kneader (manufactured by Buss Co., Ltd.), and a Kneedex (manufactured by Nippon Coke and Engineering Co., Ltd.) The resin composition obtained by melt kneading is then rolled using a twin roll or the like, and quenched with water or the like in a cooling step.

[0048] The cooled resin composition is then crushed to a desired particle size in a crushing process. In the crushing process, the resin composition is coarsely crushed using a crusher such as a crusher, hammer mill, or feather mill. The resin composition is then further crushed into fine particles using a crusher such as a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), a Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), a Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), or an air jet type crusher, to obtain toner particles.

[0049] Thereafter, if necessary, the toner particles may be classified using a classifier or sieve such as an inertial classification type Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification type Turboplex (manufactured by Hosokawa Micron Corporation), a TSP Separator (manufactured by Hosokawa Micron Corporation), or a Faculty (manufactured by Hosokawa Micron Corporation), to obtain classified toner particles.

[0050] The toner particles produced through the above steps may be used as a toner as they are, or the above external additives may be added to the toner particles.

[0051] <Other> The weight average particle size of the toner particles is preferably 4 μm or more and 12 μm or less, and more preferably 5 μm or more and 8 μm or less.

[0052] The toner can be used as a one-component developer, or may be mixed with a magnetic carrier to be used as a two-component developer. As the magnetic carrier, for example, generally known magnetic materials such as surface-oxidized iron powder, unoxidized iron powder, metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, and rare earth elements, alloy particles thereof, oxide particles, and ferrite, and magnetic material-dispersed resin carriers (so-called resin carriers) containing a magnetic material and a binder resin that holds the magnetic material in a dispersed state can be used.

[0053] When the toner is mixed with a magnetic carrier to be used as a two-component developer, good results are usually obtained when the carrier mixing ratio is, in terms of toner concentration in the two-component developer, preferably 2% by mass or more and 15% by mass or less, and more preferably 4% by mass or more and 13% by mass or less.

[0054] [Methods for measuring each physical property] The methods for measuring each physical property are described below.

[0055] <Method for measuring the acid value of binder resin> The acid value is the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of sample. Measurements are made in accordance with JIS K 0070-1992. Specifically, measurements are made on the binder resin or the crystalline resin separated from the toner using the method described below, according to the following procedure.

[0056] (1) Preparation of reagents Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume) and add ion-exchanged water to make 100 mL to obtain a phenolphthalein solution. Dissolve 7 g of special-grade potassium hydroxide in 5 mL of water and add ethyl alcohol (95% by volume) to make 1 L. Place the solution in an alkali-resistant container to avoid contact with carbon dioxide and leave for 3 days, then filter to obtain a potassium hydroxide solution. Store the resulting potassium hydroxide solution in an alkali-resistant container. The factor of the potassium hydroxide solution is determined by placing 25 mL of 0.1 mol / L hydrochloric acid in an Erlenmeyer flask, adding a few drops of the phenolphthalein solution, and titrating with the potassium hydroxide solution to determine the amount of potassium hydroxide solution required for neutralization. The 0.1 mol / L hydrochloric acid used is prepared in accordance with JIS K 8001-1998.

[0057] (2) Operation (A) Main test Precisely weigh 2.0 g of the resin sample into a 200 mL Erlenmeyer flask, add 100 mL of a toluene / ethanol (2:1) mixed solution, and dissolve it over 5 hours. Then, add a few drops of the phenolphthalein solution as an indicator and titrate with the potassium hydroxide solution. Note that the end point of the titration is when the faint red color of the indicator persists for about 30 seconds. (B) Blank test Perform the same titration as the above operation except without using the sample (i.e., using only the toluene / ethanol (2:1) mixed solution).

[0058] (3) Substitute the obtained results into the following formula to calculate the acid value. A = [(C - B) × f × 5.61] / S Here, A: acid value (mgKOH / g), B: amount of potassium hydroxide solution added in the blank test (mL), C: amount of potassium hydroxide solution added in this test (mL), f: factor of the potassium hydroxide solution, S: mass of the sample (g).

[0059] <Contents of C.I. Pigment Yellow 214 and C.I. Pigment Yellow 180> First, C.I. Pigment Yellow 214 and C.I. Pigment Yellow 180 can be removed from the toner particles in the following Procedure 1.

[0060] (Procedure 1) A sucrose concentrate was prepared by adding 160 g of sucrose to 100 mL of ion-exchanged water and dissolving it in a hot water bath. A centrifuge tube was charged with 31 g of the sucrose concentrate and 6 mL of surfactant to prepare a dispersion. 2.0 g of toner was added to the dispersion, and the toner clumps were broken down using a spatula. The centrifuge tube was then shaken in a shaker. After shaking, the solution was centrifuged at 3,500 rpm for 30 minutes with a rotation radius of 3 cm to remove the precipitate. The floating solids were filtered using a vacuum filter and then dried in a dryer for at least 1 hour. 1 g of the resulting solids was dissolved in 20 mL of tetrahydrofuran and centrifuged at 15,000 rpm for 180 minutes with a rotation radius of 3 cm. The supernatant was discarded. Another 20 mL of tetrahydrofuran was added, and the same procedure was repeated twice to obtain the precipitated solids.

[0061] An example of a surfactant is Contaminon N (manufactured by Wako Pure Chemical Industries, Ltd.), which is a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments, having a pH of 7, and which is composed of a nonionic surfactant, an anionic surfactant, and an organic builder.

[0062] The shaker used is a YS-LD manufactured by Yayoi Co., Ltd., and the mixture is shaken at 200 rpm for 1 minute.

[0063] The centrifuge used is a Front Lab FLD2012 (manufactured by AS ONE Corporation). As a result of the above, a mixture of CI Pigment Yellow 180 and CI Pigment Yellow 214 is obtained.

[0064] When the content ratio of CI Pigment Yellow 180 is A (mass%) and the content ratio of CI Pigment Yellow 214 is B (mass%), the above procedure 1 is performed on the amount of toner used, and A+B is measured from the ratio of the remaining solid content to the initial amount charged.

[0065] Next, the obtained mixture of CI Pigment Yellow 180 and CI Pigment Yellow 214 is subjected to X-ray diffraction measurement. The X-ray diffraction measurement in the toner is carried out using a measuring device "RINT-TTRII" (manufactured by Rigaku Corporation) with CuKα characteristic X-rays, in a diffraction angle range (2θ±0.20 deg) of 3 deg to 35 deg. From the total integrated intensity of the obtained spectrum, A / B can be calculated as the ratio of (peak intensity attributable to a diffraction angle (2θ) of 6.5°±0.5°) ÷ (peak intensity attributable to a diffraction angle (2θ) of 10.5°±0.5°).

[0066] The measurement conditions are as follows. X-ray:Cu / 50kV / 300mA Goniometer: Rotor horizontal goniometer (TTR-2) Attachment: Standard sample holder Divergence slit: open Divergence vertical limit slit: 10.00 mm Scattering slit: open Receiving slit: open Counter: Scintillation counter Scanning mode: Continuous Scan speed: 4.0000° / min. Sampling width: 0.0200° Scanning axis: 2θ / θ Scanning range: 10.0000~40.0000°

[0067] <Identification of crystalline resin content in toner> As described below, the content of the crystalline resin can be determined by separating the crystalline resin from the toner by utilizing the difference in solubility in a solvent. First separation: The toner is dissolved in methyl ethyl ketone (MEK) at 23°C, and the soluble matter (binder resin) is separated from the insoluble matter (crystalline polyester resin, release agent, organic pigment, inorganic fine particles, etc.). Second separation: The insoluble matter obtained in the first separation (crystalline resin, release agent, organic pigment, inorganic fine particles, etc.) is dissolved in MEK at 100°C, and the soluble matter (crystalline resin, release agent) is separated from the insoluble matter (organic pigment, inorganic fine particles, etc.). Third separation: The soluble matter (crystalline resin, release agent) obtained in the second separation is dissolved in chloroform at 23°C, and the crystalline resin is separated as the soluble matter. After the solvent is thoroughly dried and removed, the mass is measured to determine the content of the crystalline resin.

[0068] <Identification of crystalline resin monomers> The structure was analyzed using a pyrolysis gas chromatography mass spectrometer (GC-MS) as follows. 300 μg of the solid crystalline resin separated from the toner using the method described above was embedded in Pyrofoil F590 (see below) and introduced into a pyrolysis furnace. It was heated at 590°C for 5 seconds in an inert (helium) atmosphere, and the resulting decomposition gas was introduced into the gas chromatograph inlet, with the oven profile described below. The column outlet was connected to the MS analyzer via a transfer line, and a total ion chromatogram (TIC) was obtained, plotting ion current on the vertical axis and retention time on the horizontal axis. Next, mass spectra were extracted for all detected peaks in the resulting chromatogram using the accompanying software, and the compounds were assigned based on the NIST-2017 database.

[0069] The measurement device and measurement conditions are as follows. Pyrolysis furnace: Japan Analytical Industry JSP900 (manufactured by Japan Analytical Industry Co., Ltd.) Pyrofoil: F590 (Japan Analytical Industry Co., Ltd.) GC:Agilent Technologies 7890A GC MS: Agilent Technologies 5975C Column: HP-5ms 30 m, inner diameter 0.25 mm, mobile phase thickness 0.25 μm (Agilent) Carrier gas: He (purity 99.9995% or higher) Oven profile: (1) Hold at 40°C for 3 minutes, (2) Heat to 320°C at 10°C / min, (3) Hold at 320°C for 20 minutes Inlet temperature: 280℃ Split ratio: 50:1 Column flow rate: 1 mL / min (quantitative) Transfer line temperature: 280℃ Observation MS range: 30-600 Da Ionization: EI 70eV Ion source temperature: 280℃ Quadrupole temperature: 150℃

[0070] <Measurement of weight average particle size (D4) of toner (particles)> The weight average particle size (D4) of the toner (particles) is measured with an effective number of 25,000 measurement channels using a precision particle size distribution measuring device, "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), which is equipped with a 100 μm aperture tube and uses the narrow hole electrical resistance method, and the accompanying dedicated software, "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.), for setting measurement conditions and analyzing measurement data. The weight average particle size (D4) of the toner (particles) is measured with an effective number of measurement channels of 25,000, and the measurement data is analyzed and calculated.

[0071] The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, such as "ISOTON II" (manufactured by Beckman Coulter).

[0072] Before carrying out the measurements and analysis, the dedicated software is set up as follows.

[0073] In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

[0074] In the dedicated software's "Pulse to particle size conversion setting screen," set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

[0075] The specific measurement method is as follows. (1) Pour approximately 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a dilution obtained by diluting "Contaminon N" (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water is added as a dispersant. (3) A predetermined amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser, "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.), which has two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees and an electrical output of 120 W, and approximately 2 ml of the Contaminon N is added to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While ultrasonic waves are irradiated to the electrolyte solution in the beaker in (4), approximately 10 mg of toner (particles) is added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, add the electrolytic solution (5) containing dispersed toner particles to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measure the number of particles measured until it reaches 50,000. (7) The measurement data is analyzed using the dedicated software provided with the device, and the weight-average particle size (D4) is calculated. Note that when the dedicated software is set to Graph / Volume %, the "Average diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen is the weight-average particle size (D4).

[0076] [Configurations included in the embodiments of the present invention] The disclosure of this embodiment includes the following configuration. (Configuration 1) A yellow toner comprising yellow toner particles containing a binder resin and a colorant, the colorant comprises CI Pigment Yellow 180 and CI Pigment Yellow 214, When the content ratio of CI Pigment Yellow 180 in the toner is A (mass%) and the content ratio of CI Pigment Yellow 214 in the toner is B (mass%), 4.00≧A / B≧0.25 20.0≧A+B≧5.0 and The binder resin has an acid value of 3 mgKOH / g or more. (Configuration 2) The yellow toner according to configuration 1, wherein the binder resin has an acid value of 5 mgKOH / g or more and 20 mgKOH / g or less. (Configuration 3) The yellow toner according to configuration 1 or 2, wherein the binder resin is a polyester resin. (Configuration 4) The yellow toner according to any one of Configurations 1 to 3, wherein the binder resin contains 1% by mass or more and 15% by mass or less of a crystalline polyester. (Configuration 5) The yellow toner according to Configuration 4, wherein the crystalline polyester has an acid value of 3 mgKOH / g or more. (Configuration 6) The yellow toner according to Configuration 4, wherein the alcohol component of the crystalline polyester has 2 to 12 carbon atoms and the acid component has 2 to 14 carbon atoms. (Configuration 7) The yellow toner according to Configuration 6, wherein the crystalline polyester monomer has an alcohol component of ethylene glycol and an acid component of dodecanedioic acid. (Configuration 8) The yellow toner according to any one of configurations 1 to 7, wherein the binder resin contains a polyethylene terephthalate segment. (Configuration 9) The yellow toner according to Configuration 8, wherein the polyethylene terephthalate segment in the binder resin accounts for 1% by mass to 20% by mass of the binder resin. [Example]

[0077] The present invention will be described in more detail with reference to the following examples, which, however, are not intended to limit the scope of the present invention. Unless otherwise specified, the "parts" in the following formulations are all by mass.

[0078] <Production example of polyester resin 1> The following materials were placed in a reaction vessel equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube under a nitrogen atmosphere. Polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane: 71.6 parts (100.0 mol% based on the total number of moles of polyhydric alcohols) Terephthalic acid: 20.6 parts (70.0 mol% based on the total number of moles of polycarboxylic acids) Adipic acid: 2.1 parts (10.0 mol% based on the total number of moles of polycarboxylic acids) Fumaric acid: 2.1 parts (10.0 mol% based on the total number of moles of polycarboxylic acids) Polyethylene terephthalate: 5.1 parts Titanium tetrabutoxide (polymerization catalyst): 2.0 parts

[0079] Next, the atmosphere in the flask was replaced with nitrogen gas, and the temperature was gradually raised with stirring. The mixture was stirred at 220°C and reacted for 5 hours while distilling off the water produced. The reaction was stopped by lowering the temperature, and polyester resin 1 was obtained. The acid value was 10.2 mgKOH / g.

[0080] <Production Examples of Polyester Resins 2 to 10> Polyester resins 2 to 10 were obtained in the same manner as in Production Example of Polyester Resin 1, except that the materials and reaction time in Production Example of Polyester Resin 1 were changed as shown in Table 1.

[0081] [Table 1]

[0082] <Production Example of Crystalline Resin 1> Ethylene glycol: 28.0 parts Dodecanedioic acid: 72.0 parts Titanium tetrabutoxide (polymerization catalyst): 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was allowed to react for 5 hours at 200°C while stirring, yielding Crystalline Resin 1. The acid value of the resulting resin was 10.0 mgKOH / g.

[0083] <Production Example of Crystalline Resin 2> Hexanediol: 53.0 parts Hexane diacid: 47.0 parts Titanium tetrabutoxide (polymerization catalyst): 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was allowed to react for 5 hours at 200°C while stirring, yielding Crystalline Resin 2. The acid value of the resulting resin was 10.2 mgKOH / g.

[0084] <Production Example of Crystalline Resin 3> Ethylene glycol: 28.0 parts Dodecanedioic acid: 72.0 parts Titanium tetrabutoxide (polymerization catalyst): 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was allowed to react for 8 hours at 200°C while stirring, yielding Crystalline Resin 3. The acid value of the resulting resin was 5.3 mgKOH / g.

[0085] <Production Example of Crystalline Resin 4> Ethylene glycol: 28.0 parts Dodecanedioic acid: 72.0 parts Titanium tetrabutoxide (polymerization catalyst): 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet, and a thermocouple. The atmosphere in the flask was then replaced with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was allowed to react for 12 hours at 200°C while stirring, yielding Crystalline Resin 4. The acid value of the resulting resin was 2.4 mgKOH / g.

[0086] <Production example of yellow pigment masterbatch YM1> CI Pigment Yellow 180 (Toner Yellow HG, manufactured by Heubach Color Japan Co., Ltd.): 24 parts CI Pigment Yellow 214 (PV Fast Yellow H9G, manufactured by Heubach Color Japan Co., Ltd.): 16 parts Polyester resin 1: 60 parts The above materials were mixed in a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20 s. -1 After mixing for a rotation time of 5 minutes, the mixture was kneaded in a twin-screw kneader (PCM-30 model, manufactured by Ikegai Corporation) at a temperature of 120° C. The resulting kneaded mixture was cooled and coarsely pulverized in a pin mill to a volume average particle size of 100 μm or less, to obtain a coarsely pulverized product of yellow pigment masterbatch YM1.

[0087] <Production of yellow pigment masterbatches YM2 to YM14> Except for changing the materials shown in Table 2, the same production method as for the yellow pigment masterbatch YM1 was used to obtain yellow pigment masterbatches YM2 to YM14.

[0088] [Table 2] *Styrene-acrylic resin 1: [Styrene-acrylic resin (styrene:n-butyl acrylate:acrylic acid = 71:28:1), acid value = 9.4 mg KOH / g]

[0089] <Production of Yellow Toner YT1> Polyester resin 1: 73.9 parts ·Crystalline resin 1: 5.0 parts Pigment masterbatch YM1: 13.1 parts Wax 1: 8.0 parts (Hydrocarbon wax, maximum endothermic peak temperature 90℃) The above materials were mixed in a Henschel mixer (FM-75 model, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20 s. -1 After mixing for 5 minutes, the mixture was kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) at a set temperature of 130°C. The resulting kneaded mixture was cooled and coarsely pulverized in a pin mill to a volume average particle size of 100 μm or less to obtain a coarsely pulverized product. The resulting coarsely pulverized product was finely pulverized in a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.) by adjusting the rotation speed and number of passes to obtain the target particle size. The mixture was further classified using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles.

[0090] The rotation speed of a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) was adjusted to obtain the target particle size and particle size distribution, and classification was performed. 100 parts of the obtained toner particles were mixed with a toner having a specific surface area of ​​200 m2 measured by the BET method. 2 1.8 parts of silica particles hydrophobized with silicone oil were added, and the mixture was mixed in a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 30 s -1 The mixture was mixed at a rotation time of 10 minutes to obtain a yellow toner YT1.

[0091] <Production example of yellow toner YT2 to YT12> Except for changing the materials shown in Table 3, the same production method as for yellow toner YT1 was used to obtain yellow toners YT2 to YT12.

[0092] <Production example of yellow toner YT13> Yellow toner YT13 was obtained in the same manner as in the production example for yellow toner YT1, except that polyester resin 1 was changed to styrene-acrylic resin 1 [styrene-acrylic resin (styrene:n-butyl acrylate:acrylic acid=71:28:1), acid value=9.4 mgKOH / g].

[0093] <Production example of yellow toner YT14-25> Except for changing the materials shown in Table 3, the same production method as for yellow toner YT1 was used to obtain yellow toners YT14 to YT25.

[0094] [Table 3-1]

[0095] [Table 3-2]

[0096] <Magnetic Carrier 1 Manufacturing Example> Number average particle size: 0.30 μm, magnetization strength: 65 Am under a magnetic field of 1000 / 4π (kA / m) 2 / kg) of magnetite 1 Number average particle size: 0.50 μm, magnetization strength: 65 Am under a magnetic field of 1000 / 4π (kA / m) 2 / kg) of magnetite2 To 100 parts of each of the above materials, 4.0 parts of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane) was added, and the mixture was mixed and stirred at high speed in a container at 100° C. or higher to treat each of the fine particles.

[0097] Phenol: 10% by weight Formaldehyde solution: 6% by mass (40% by mass of formaldehyde, 10% by mass of methanol, 50% by mass of water) Magnetite treated with the above silane compound 1:58 mass% Magnetite treated with the above silane compound 2: 26 mass% 100 parts of the above materials, 5 parts of a 28% by weight aqueous ammonia solution, and 20 parts of water were placed in a flask, and the mixture was stirred and mixed while heating to 85°C over 30 minutes and maintaining the temperature. The resulting phenolic resin was then polymerized for 3 hours to harden. The hardened phenolic resin was then cooled to 30°C, and water was added. The supernatant was removed, and the precipitate was washed with water and air-dried. This was then dried under reduced pressure (5 mmHg or less) at 60°C to obtain spherical magnetic carrier 1 with dispersed magnetic material. The volume-based 50% particle size (D50) of magnetic carrier 1 was 34.2 μm.

[0098] <Production example of yellow two-component developer YD1> 8.0 parts of yellow toner YT1 was added to 92.0 parts of magnetic carrier 1, and mixed in a V-type mixer (V-20, manufactured by Seishin Enterprises) to obtain yellow two-component developer YD1.

[0099] <Yellow two-component developer YD2 to YD25> Except for changing the toner shown in Table 4, the same production method as for yellow two-component developer YD1 was used to obtain yellow two-component developers YD2 to YD25.

[0100] Example 1 A Canon full-color copier imagePress C810 was used as the image forming apparatus, and the prepared two-component developer YD1 was placed in a yellow developing device of the image forming apparatus, and the above-mentioned toner YT1 was placed in a yellow toner container, and the following various evaluations were performed.

[0101] <Evaluation of Scratch Resistance> Paper: Image Coat Gloss 158 (158.0 g / m 2 ) (Sold by Canon Marketing Japan Inc.) Toner amount on paper: 0.05 mg / cm2 (Adjusted by DC voltage VDC of the developer carrier, charging voltage VD of the electrostatic latent image carrier, and laser power) The development conditions were adjusted to achieve the above-mentioned amount. A 3 cm x 15 cm image was placed and formed in the center of the A4 paper in a high temperature and high humidity environment (H / H: temperature 30°C, relative humidity 80%) at a process speed of 400 mm / sec. Then, using the fixing test jig described above, the image was fixed at an upper belt temperature of 180°C and a lower belt temperature of 85°C.

[0102] The evaluation image was output and the scratch resistance was evaluated. The difference in reflectance was used as an index for evaluating scratch resistance.

[0103] First, the image portion of the evaluation image is rubbed (10 times back and forth) with a new evaluation paper under a load of 0.5 kgf using a Gakushin-type rub fastness tester (AB-301, manufactured by Tester Sangyo Co., Ltd.). Then, using a reflectometer (REFLECTOMETER MODEL TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.), the reflectance of the portion rubbed with the new evaluation paper (reflectance after rubbing) and the reflectance of the portion not rubbed (reflectance before rubbing) are measured.

[0104] And the following formula Reflectance difference = reflectance before friction - reflectance after friction The difference in reflectance before and after rubbing was calculated using the formula. The obtained difference in reflectance was evaluated according to the following evaluation criteria. If the evaluation was A to C, it was judged to be good. The evaluation results are shown in Table 4. (Evaluation criteria: Scratch resistance) A: Less than 3.0% B: 3.0% or more and less than 4.0% C: 4.0% or more and less than 5.0% D: 5.0% or more and less than 10.0% E: 10.0% or more

[0105] <Evaluation of image gloss> Image gloss rating: Paper: OK top coat + (A4 127.9 g / m 2The toner amount on the paper was 0.45 mg / cm. 2 The development conditions were adjusted so that the DC voltage VDC of the developer carrier, the charging voltage VD of the electrostatic latent image carrier, and the laser power were used. A 3 cm x 15 cm solid unfixed image was formed in the center of the A4 paper in a high temperature and high humidity environment (H / H: temperature 30°C, relative humidity 80%) at a process speed of 400 mm / sec.

[0106] Then, using the above-mentioned fixing test jig, fixing was performed in a high temperature and high humidity environment (H / H: temperature 30°C, relative humidity 80%), with the fixing speed adjusted to 400 mm / sec, and the upper belt temperature fixed at 180°C and the lower belt temperature fixed at 85°C.

[0107] Image gloss (gloss) was measured using a handheld gloss meter PG-1M (manufactured by Nippon Denshoku Industries Co., Ltd.) with the incident and receiving angles both set to 60°. A higher gloss value indicates that the image surface is smooth, glossy, and of high quality with high saturation; conversely, a lower gloss value indicates that the image surface is dull, low in saturation, and rough.

[0108] The evaluation was performed according to the following evaluation criteria. A rating of A to D was determined to be good. The evaluation results are shown in Table 4. (Evaluation criteria: Gross) A: Gross value is 30 or more B: Gross value is 26 or more and less than 30 C: Gross value is 22 or more and less than 26 D: Gross value is 18 or more and less than 22 E: Gross value less than 18

[0109] <Gross stability evaluation> For the gloss stability evaluation, the temperature of the upper belt of the fixing test jig was adjusted in 20°C increments in the range of 140 to 200°C while the temperature of the lower belt of the fixing test jig was fixed at 85°C in the same manner as in the gloss evaluation described above, and the image gloss (gloss) was measured at each fixing temperature. Then, gloss was plotted on the vertical axis and fixing temperature on the horizontal axis, and the slope of the approximated line was determined and evaluated according to the following evaluation criteria. A rating of A to C was considered good. The evaluation results are shown in Table 4.

[0110] (Evaluation criteria: Gross stability) A: The slope of the approximate line is less than 0.20 B: The slope of the approximate line is 0.20 or more and less than 0.30 C: The slope of the approximate line is 0.30 or more and less than 0.40 D: The slope of the approximate line is 0.40 or more and less than 0.50 E: The slope of the approximate line is 0.50 or more.

[0111] <Measurement of image density change> The evaluation paper was plain paper GF-C081 (A4, basis weight 81.4 g / m 2 (sold by Canon Marketing Japan Inc.) was used.

[0112] The amount of toner on the paper in a FFh image (solid image) is 0.45 mg / cm 2 The print speed was adjusted to 400 mm / sec, and the process speed was also adjusted to 400 mm / sec. FFh is the hexadecimal representation of 256 gradations, with 00h being the first gradation of 256 gradations (white background) and FF being the 256th gradation of 256 gradations (solid area). First, an image output test of 1,000 sheets was conducted at an image ratio of 1%. During the continuous printing of 1,000 sheets, the sheets were printed under the same development and transfer conditions (without calibration) as the first sheet.

[0113] After that, an image output test of 1,000 sheets was conducted at an image ratio of 80%. During the continuous printing of 1,000 sheets, the sheets were printed under the same development and transfer conditions (without calibration) as the first sheet. The image density of the 1,000th sheet printed at an image ratio of 1% was taken as the initial density, and the density of the 1,000th image printed at an image ratio of 80% was measured and evaluated.

[0114] The above test was conducted in a high temperature and high humidity environment (H / H: temperature 30°C, relative humidity 80%). Using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), the initial density and the density of the 1,000th image printed at an image ratio of 80% were measured, and the difference Δ was used to rank the prints according to the following criteria. A grade of D or higher was considered good. The evaluation results are shown in Table 4. (Evaluation criteria: image density difference Δ) A: Less than 0.020 B: 0.020 or more and less than 0.050 C: 0.050 or more and less than 0.100 D: 0.100 or more and less than 0.150 E: 0.150 or more

[0115] [Examples 2 to 20, Comparative Examples 1 to 5] Evaluation was performed in the same manner as in Example 1, except that the two-component developer placed in the yellow developing device of the image forming apparatus and the toner placed in the yellow toner container were changed to those shown in Table 4. The evaluation results are shown in Table 4.

[0116] In Examples 1 to 20, which satisfy the requirements of the present invention, an interaction is exerted between a weak crosslinked structure formed by hydrogen bonding between the carboxylic acid of the resin and the primary and secondary amide groups of CI Pigment Yellow 214, and a gentle crosslinked structure due to van der Waals forces of CI Pigment Yellow 180, thereby achieving a good gloss image, gloss stability, image density stability, and scratch resistance of the printed area. In contrast, in Comparative Examples 1 to 5, which lack any of the requirements of the present invention, the interaction is not exerted, and therefore the compatibility of the above properties cannot be achieved.

[0117]

Table 4

Claims

1. A yellow toner comprising yellow toner particles containing a binder resin and a colorant, The colorant contains C.I. Pigment Yellow 180 and C.I. Pigment Yellow 214, When the content ratio of C.I. Pigment Yellow 180 in the toner is A (mass%) and the content ratio of C.I. Pigment Yellow 214 in the toner is B (mass%), 4.00≧A / B≧0.25 20.0≧A+B≧5.0 and The binder resin has an acid value of 3 mgKOH / g or more.

2. 2. The yellow toner according to claim 1, wherein the binder resin has an acid value of 5 mgKOH / g or more and 20 mgKOH / g or less.

3. 3. The yellow toner according to claim 1, wherein the binder resin is a polyester resin.

4. 3. The yellow toner according to claim 1, wherein the binder resin contains 1% by mass or more and 15% by mass or less of a crystalline polyester.

5. 5. The yellow toner according to claim 4, wherein the crystalline polyester has an acid value of 3 mgKOH / g or more.

6. 5. The yellow toner according to claim 4, wherein the alcohol component of the crystalline polyester has 2 to 12 carbon atoms and the acid component has 2 to 14 carbon atoms.

7. 7. The yellow toner according to claim 6, wherein the crystalline polyester monomer has an alcohol component of ethylene glycol and an acid component of dodecanedioic acid.

8. 3. The yellow toner according to claim 1, wherein the binder resin contains a polyethylene terephthalate segment.

9. 9. The yellow toner according to claim 8, wherein the polyethylene terephthalate segment in the binder resin accounts for 1% by mass or more and 20% by mass or less of the binder resin.

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