White toner for electrostatic image development

Abstract

Regarding a white toner for electrostatic image development with excellent weather resistance. [Solution] A white toner for developing electrostatic images, comprising a binder resin containing amorphous polyester resin A and titanium dioxide, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate.

Description

[Technical Field]

[0001] This invention relates to a white toner for developing electrostatic images, used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] Titanium dioxide is commonly used as a coloring agent for white toner (see Patent Document 1).

[0003] On the other hand, the use of polyethylene terephthalate as a raw material for the binder resin of toner is being considered (see Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-173361 [Patent Document 2] Japanese Patent Publication No. 2023-88255 [Overview of the project] [Problems that the invention aims to solve]

[0005] Because titanium dioxide is photoactive, its color is prone to change depending on environmental conditions, such as prolonged exposure to ultraviolet light, and further improvements are needed in the weather resistance of white toner printed materials.

[0006] This invention relates to a white toner for electrostatic image development that has excellent weather resistance. [Means for solving the problem]

[0007] The present invention relates to a white toner for electrostatic image development containing an amorphous polyester resin A and titanium dioxide, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. [Effects of the Invention]

[0008] The white toner for electrostatic charge image development of the present invention exhibits excellent effects in terms of weather resistance.

Mode for Carrying Out the Invention

[0009] The white toner for electrostatic charge image development of the present invention has a major feature in that it contains titanium oxide as a white colorant and an amorphous polyester resin A which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (hereinafter referred to as "PET"). Although the reason for the effects of the present invention is not clear, it is presumed as follows. The following mechanism is a presumption and is not limited thereto.

[0010] In the present invention, by using a polycondensate of an alcohol component, a carboxylic acid component, and PET (amorphous polyester resin A), the weather resistance of printed matter is improved. In the polycondensation reaction of the alcohol component, the carboxylic acid component, and PET, although PET undergoes depolymerization and is incorporated into the polyester resin chain by transesterification, it is not completely randomized and exists as a unit of a certain length called a PET segment in the resin. By containing an amorphous polyester resin obtained using PET as a binder resin together with titanium oxide in the toner, the PET segments where ester groups are concentrated act on titanium oxide like a chelate, and it is considered that the weather resistance of the printed matter is improved because titanium oxide is stabilized from ultraviolet rays.

[0011] The amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and PET.

[0012] From the viewpoint of low-temperature fixing property, the alcohol component has the formula (I):

[0013]

Chemical Formula

[0014] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number, and the sum of x and y is 1 or greater, preferably 1.5 or greater, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) It is preferable to include an alkylene oxide adduct of bisphenol A represented by formula (I). Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A. It is preferable to use one or more of these.

[0015] The content of the bisphenol A alkylene oxide adduct represented by formula (I) is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, in the alcohol component. However, the ethylene glycol units of PET are not included in the alcohol component as referred to herein.

[0016] Other alcohol components include aliphatic diols and trivalent or higher alcohols.

[0017] Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butanediol, and neopentyl glycol.

[0018] Examples of alcohols with a hydride of 3 or higher include glycerin, trimethylolpropane, and pentaerythritol.

[0019] From the viewpoint of resistance to hot offsetting, the carboxylic acid component preferably includes an aromatic dicarboxylic acid compound.

[0020] Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0021] The content of aromatic dicarboxylic acid compounds is preferably 35 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, even more preferably 50 mol% or more, and 100 mol% or less, of the carboxylic acid component. If the carboxylic acid component includes trivalent or higher carboxylic acid compounds, the content is preferably 90 mol% or less, more preferably 85 mol% or less. However, the terephthalic acid units contained in PET are not included in the carboxylic acid component as referred to herein.

[0022] Other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0023] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0024] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0025] In PET, ethylene glycol and terephthalic acid, produced by the polycondensation reaction of an alcohol component and a carboxylic acid component, and / or by the depolymerization of a portion of PET, are subjected to a polycondensation reaction as raw material monomers and incorporated into the polyester resin.

[0026] The PET can be either new virgin PET or recycled PET. Recycled PET refers to material obtained by collecting used PET, washing it as needed, separating it from other materials, crushing it, depolymerizing the crushed material to monomer units, and then resynthesizing it using these monomers as raw materials.

[0027] In this invention, it is preferable that the PET has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. By introducing low IV value (low molecular weight) PET into the polyester resin, the depolymerization of PET proceeds more uniformly.

[0028] From the viewpoint of the above, the IV value of PET is preferably 0.40 or higher, more preferably 0.45 or higher, even more preferably 0.50 or higher, and still more preferably 0.55 or higher. From the viewpoint of low-temperature fixability and homogenization of depolymerization, it is preferably 0.85 or lower, more preferably 0.80 or lower, even more preferably 0.75 or lower, even more preferably 0.70 or lower, and still more preferably 0.65 or lower. The IV value is the intrinsic viscosity and serves as an indicator of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc.

[0029] Commercially available PET products with an IV value between 0.40 and 0.85 include RAMAPET L1 (manufactured by Indorama Ventures, IV value: 0.60), RAMAPET BF3067 (manufactured by Indorama Ventures, IV value: 0.65), RAMAPET N2G (manufactured by Indorama Ventures, IV value: 0.75), TRN-NTJ (manufactured by Teijin Limited, IV value: 0.53), TRN-RTJC (manufactured by Teijin Limited, IV value: 0.64), RAMAPET S1 (manufactured by Indorama Ventures, IV value: 0.84), and UK-31 (manufactured by Utsumi Recycle Systems Co., Ltd., IV value: 0.67).

[0030] The content of low-IV PET is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and 100% by mass or less, of the total amount of PET subjected to polycondensation.

[0031] The PET content is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, and preferably 75 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less, from the viewpoint of weather resistance, relative to the total amount of alcohol component, carboxylic acid component, and PET. Since PET is an equimolar polycondensate of ethylene glycol, terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is considered as 1 mole. Therefore, the number of moles of PET = the number of moles of ethylene glycol units = the number of moles of terephthalic acid units. If amorphous polyester resin A consists of two or more resins, the weighted average value of the PET content of each resin shall be used as the PET content of amorphous polyester resin A.

[0032] The equivalent ratio (COOH group / OH group) of the carboxylic acid component (including terephthalic acid units in PET) to the alcohol component (including ethylene glycol units in PET) is preferably 0.6 or higher, more preferably 0.7 or higher, even more preferably 0.8 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower.

[0033] Amorphous polyester resin A can be produced, for example, by polycondensing an alcohol component, a carboxylic acid component, and PET in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and optionally in the presence of a co-catalyst, polymerization inhibitor, etc., at a temperature preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0034] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamine) and titanium dihydroxybis(triethanolamine). The amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total amount of alcohol component, carboxylic acid component, and PET. Examples of co-catalysts for the esterification catalyst include gallic acid. The amount of co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, per 100 parts by mass of the total amount of alcohol component, carboxylic acid component, and PET. Examples of polymerization inhibitors include tert-butylcatechol. The amount of polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, based on 100 parts by mass of the total amount of alcohol component, carboxylic acid component, and PET.

[0035] In this invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins that have been grafted or blocked with phenol, urethane, epoxy, etc., by methods described in Japanese Patent Publication No. 11-133668, Japanese Patent Publication No. 10-239903, Japanese Patent Publication No. 8-20636, etc. Among modified polyester resins, urethane-modified polyester resins obtained by urethane elongation of polyester resin with a polyisocyanate compound are preferred.

[0036] The softening point of amorphous polyester resin A is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of resistance to hot offset and gloss.

[0037] The crystallinity of a resin is expressed by a crystallinity index, which is defined by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum endothermic peak temperature]. The amorphous resin is one in which no endothermic peak is observed, or, if observed, a resin with a crystallinity index greater than 1.4, preferably greater than 1.5, more preferably 1.6 or higher, or less than 0.6, preferably 0.5 or lower. On the other hand, the crystalline resin is a resin having a crystallinity index of 0.6 or higher, preferably 0.7 or higher, more preferably 0.9 or higher, and 1.4 or lower, preferably 1.2 or lower, more preferably 1.1 or lower. The crystallinity of a resin can be adjusted by the type and ratio of raw material monomers, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate). The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0038] The glass transition temperature of amorphous polyester resin A is preferably 40°C or higher, more preferably 50°C or higher, and preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of resistance to hot offset and gloss.

[0039] The acid value of amorphous polyester resin A is preferably 1 mg KOH / g or more, more preferably 3 mg KOH / g or more, and preferably 20 mg KOH / g or less, and more preferably 18 mg KOH / g or less, from the viewpoint of low-temperature fixability and storage properties.

[0040] The content of amorphous polyester resin A in the binder resin is preferably 40% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less.

[0041] The binder resin may further contain resins other than amorphous polyester resin A. Other resins include amorphous polyester resins which are polycondensates of alcohol and carboxylic acid components that do not use PET, crystalline polyester resins, vinyl resins such as styrene-acrylic resins, polyamide resins, epoxy resins, polycarbonate resins, polyurethane resins, and composite resins containing two or more of these resins. Among these, crystalline polyester resins are preferred from the viewpoint of low-temperature fixation.

[0042] The PET content in the binder resin is preferably 2 mol% or more, more preferably 4 mol% or more, even more preferably 8 mol% or more, and preferably 75 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. If the binder resin consists of two or more resins, the weighted average value of the PET content of each resin is used as the PET content in the binder resin, and the PET content of each resin is the content in the total amount of alcohol component, carboxylic acid component, and PET.

[0043] Furthermore, the binder resin preferably contains two types of resins with different softening points, from the viewpoint of low-temperature fixability and fixation width. The difference in softening points between the two types of resins is preferably 10°C or more, more preferably 20°C or more, and preferably 60°C or less, more preferably 40°C or less.

[0044] The softening point of the resin with the higher softening point (resin AH) is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of resistance to hot offset.

[0045] Furthermore, the softening point of the resin with the lower softening point (resin AL) is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower, from the viewpoint of glossiness.

[0046] Either resin AH or resin AL may be amorphous polyester resin A, or both may be amorphous polyester resin A. If either one is amorphous polyester resin A, the other resin is preferably amorphous polyester resin B, which is a polycondensate of alcohol and a carboxylic acid component that does not use PET. When the binder resin consists of amorphous polyester resin A and amorphous polyester resin B, it is preferable that the weighted average value of the PET content of each resin is within the range of the aforementioned PET content.

[0047] The mass ratio of resin AH to resin AL (resin AH / resin AL) is preferably 10 / 90 or more, more preferably 20 / 80 or more, even more preferably 30 / 70 or more, even more preferably 40 / 60 or more, and preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 70 / 30 or less, and even more preferably 60 / 40 or less.

[0048] The binder resin content in the toner is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and preferably 83% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0049] The white toner of the present invention contains titanium dioxide as a coloring agent from the viewpoint of improving the whiteness density of the white toner. The titanium dioxide content is preferably 90% by mass or more in the coloring agent, and it is more preferable to use only titanium dioxide as the coloring agent, but other coloring agents other than titanium dioxide may be included as long as the effect of white color development is not impaired. Examples of other coloring agents include zinc oxide, aluminum oxide, hollow resin particles, etc.

[0050] Titanium dioxide can be used in any of the following crystalline forms: anatase, rutile, or brookite. Of these, the rutile form is preferred from the viewpoint of stability and availability.

[0051] From the viewpoint of obtaining good dispersibility in toner particles, titanium dioxide is preferably surface-treated. The surface treatment of titanium dioxide is not particularly limited, and either organic or inorganic surface treatment may be applied. From the viewpoint of avoiding the influence of photocatalysis, titanium dioxide surface-treated with an inorganic substance is preferred, and titanium dioxide surface-treated with at least one of silica and alumina is more preferred.

[0052] The number-average particle size of titanium dioxide is preferably 150 nm or more, more preferably 200 nm or more, and even more preferably 230 nm or more, from the viewpoint of improving the whiteness density of the white toner and improving its opacity. Furthermore, from the viewpoint of improving the productivity of the toner and improving its resistance to hot offset, it is preferably 350 nm or less, more preferably 300 nm or less, and even more preferably 270 nm or less.

[0053] Examples of commercially available titanium dioxide products include "Typake CR-50-2," "Typake CR-58," "Typake CR-60-2," and "Typake CR-80" (all manufactured by Ishihara Sangyo Co., Ltd.).

[0054] The titanium dioxide content is preferably 20 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of amorphous polyester resin A, and from the viewpoint of pigment dispersibility, preferably 150 parts by mass or less, more preferably 135 parts by mass or less, and even more preferably 115 parts by mass or less.

[0055] In addition to the binder resin (binder) and titanium dioxide, the white toner of the present invention may contain additives such as release agents, charge control agents, magnetic powders, flowability improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties improvers.

[0056] Examples of mold release agents include hydrocarbon waxes and their oxides, such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; ester waxes such as carnauba wax, montane wax and their deoxidizing waxes, and fatty acid ester waxes; and fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc., which can be used individually or in combination of two or more.

[0057] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of toner transferability, and preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower, from the viewpoint of low-temperature fixation.

[0058] The release agent content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, from the viewpoint of the toner's low-temperature fixing performance, hot offset resistance, and dispersibility in the binder resin, per 100 parts by mass of the binder resin.

[0059] The charge control agent is not particularly limited and may contain either a positively charged charge control agent or a negatively charged charge control agent.

[0060] Positively charged charge control agents include nigrosine dyes, such as "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-04," "Bontron N-07," "Bontron N-09," "Bontron N-11," and "Bontron N-79" (all manufactured by Orient Chemical Industries, Ltd.); triphenylmethane-based dyes containing tertiary amines as side chains; quaternary ammonium salt compounds, such as "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, and "COPY CHARGE PX." Examples include VP435 (manufactured by Clariant), polyamine resins such as AFP-B (manufactured by Orient Chemical Industries, Ltd.), imidazole derivatives such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemicals, Ltd.), and styrene-acrylic resins such as FCA-701PT and FCA-201-PS (manufactured by Fujikura Chemicals, Ltd.).

[0061] Furthermore, as negative charge control agents, polymer types such as "FCA-2521NJ" (manufactured by Fujikura Chemical Co., Ltd.), etc.; metal-containing azo dyes such as "Barifast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" (all manufactured by Orient Chemical Industry Co., Ltd.), "Eisenspiron Black TRH", "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; metal compounds of benzyl acid compounds such as "LR-147", "LR-297" (both manufactured by Nippon Carlit Co., Ltd.), etc.; metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", "Bontron E-304" (all manufactured by Orient Chemical Industry Co., Ltd.), "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE Examples include "NX VP434" (manufactured by Clariant), nitroimidazole derivatives, organometallic compounds, etc.

[0062] From the viewpoint of the charge stability of the toner, the content of the charge control agent is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the binder resin. However, if the charge control agent is of the polymer type, it is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7.5 parts by mass or less, per 100 parts by mass of the binder resin.

[0063] The white toner of the present invention may be a toner obtained by any of the conventionally known methods, such as the melt-kneading method, the emulsification-coagulation method, the suspension polymerization method, or the dissolution-suspension method, and may also be a toner having a core-shell structure. However, from the viewpoint of the miscibility of the toner components, a pulverized toner is preferred, and a pulverized toner obtained by the melt-kneading method, that is, a pulverized toner obtained by a method including the steps of melt-kneading the raw materials and pulverizing the resulting mixture, is more preferred. Specifically, for example, an amorphous polyester resin A and titanium dioxide, and optionally raw materials such as a mold release agent and a charge control agent, can be uniformly mixed in a mixer such as a Henschel mixer, then melt-kneaded in a closed-type kneader, a single-screw or twin-screw extruder, an open-roll type kneader, etc., and then cooled, pulverized, and classified to produce the toner.

[0064] In the toner of the present invention, it is preferable to use an external additive to improve fluidity. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and two or more may be used in combination. Among these, silica is preferred, and from the viewpoint of toner fluidity, hydrophobic silica that has been hydrophobicized is more preferred.

[0065] Examples of hydrophobic agents used to hydrophobize the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0066] The average particle size of the external additive is preferably 10 nm or larger, more preferably 250 nm or smaller, more preferably 200 nm or smaller, and even more preferably 90 nm or smaller, from the viewpoint of the toner's chargeability, fluidity, and transferability.

[0067] External additive treatment, which involves mixing toner particles with external additives, can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

[0068] From the viewpoint of the toner's electrostatic properties, fluidity, and transferability, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, and more preferably 4 parts by mass or less, per 100 parts by mass of toner particles before treatment with the external additive.

[0069] The volume-intermediate particle size (D) of the toner of the present invention 50 The volume median particle size (D) is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency calculated using volume fractions accounts for 50% when calculated from the smallest particle size. Furthermore, if the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is taken as the volume median particle size of the toner.

[0070] The toner of the present invention can be used as is as a one-component developing toner, or as a two-component developing toner used in combination with a carrier, in image forming apparatuses using either a one-component developing method or a two-component developing method, respectively. [Examples]

[0071] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. The physical properties of resins, etc., can be measured by the following methods.

[0072] [PET IV value] The phenol / tetrachloroethane is dissolved at a concentration of 4 g / L in a 60 / 40 (mass ratio) mixed solvent, and the concentration is measured using an Ubbelohde viscometer and calculated using the following formula. IV = (-1 + √(1 + 4kη)) / (2kC) [In the formula, k = 0.33, C = 0.004 g / mL, and η = (t1 / t0) - 1 (t0: number of seconds for the solvent to fall, t1: number of seconds for the sample solution to fall).]

[0073] [Amine value of ketimine compounds] The measurement will be performed according to the method of JIS K2501:2003. However, the measurement solvent will be changed from chlorobenzene to chloroform as specified in JIS K2501:2003.

[0074] [Softening point of resin] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester is plotted against temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0075] [Maximum peak temperature of endothermic resin] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintained at 0°C for 1 minute. Then, measurements are taken at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0076] [Glass transition temperature of resins] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled to -50°C at a rate of 10°C / min. Next, the sample is heated at a rate of 10°C / min and the endothermic peak is measured. The temperature at the intersection of the baseline extension below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rise of the peak to the peak apex is defined as the glass transition temperature.

[0077] [Acid value of resins] Measurements will be performed according to the method of JIS K 0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixed solvent specified in JIS K 0070 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0078] [Number average particle size of titanium dioxide and external additives] The number-average particle size is determined by measuring the particle size (average value of major and minor axes) of 100 particles (primary particles) using a scanning electron microscope (SEM) at an appropriate magnification of 5,000 to 50,000x, and then using the average value of these measurements as the number-average particle size for titanium dioxide, silica particles, and external additives.

[0079] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated again at a rate of 10°C / min, the amount of heat is measured, and the maximum peak temperature of endothermic heating is defined as the melting point.

[0080] [Volume median particle size and CV value of resin particles, colorant particles, mold release agent particles, and polymer dispersants] (1) Measuring device: Laser diffraction particle size analyzer "LA-920" (manufactured by Horiba, Ltd.) (2) Measurement conditions: Take the sample dispersion into a measuring cell, add distilled water, and measure the volume mid-particle size (D) at a temperature where the absorbance is within the appropriate range. 50 The volume-average particle size is measured. The CV value is calculated according to the following formula. CV value (%) = (Standard deviation of particle size distribution / Volume-average particle size) × 100

[0081] [Solid content concentration of resin dispersion, colorant dispersion, and mold release agent dispersion] Using the infrared moisture meter "FD-230" (manufactured by Kett Scientific Research Institute Co., Ltd.), 5g of the sample to be measured was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, variation range 0.05%), and the moisture content (mass%) of the dispersion was measured. The solid content concentration was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0082] [Medium particle size by volume of aggregated particles] • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte solution to adjust the concentration to one that could measure the particle size of 30,000 particles in 20 seconds. Then, the 30,000 particles were measured, and the volume median particle size (D) was determined from the particle size distribution. 50 )

[0083] [Toner volume medium particle size (D 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: Add 10 mg of the sample to 5 mL of the dispersion and disperse for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80W). Then, add 25 mL of electrolyte and disperse for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, the 30,000 particles are measured, and the volume median particle size (D) is determined from the particle size distribution. 50 )

[0084] [Toner circularity] The circularity of the toner particles will be measured under the following conditions. • Measurement device: Flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) • Preparation of dispersion: Prepare the dispersion of toner particles by diluting it with deionized water so that the solid content concentration is 0.001 to 0.05% by mass. • Measurement mode: HPF measurement mode

[0085] Resin manufacturing example 1 The alcohol components, carboxylic acid components other than trimellitic anhydride, PET, esterification catalyst, and co-catalyst shown in Tables 1 and 2 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride shown in Tables 1 and 2 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Tables 1 and 2 was reached, yielding amorphous polyester resins (resins AH1-AH5, AH8, AH10-AH13). The physical properties are shown in Tables 1 and 2.

[0086] Resin manufacturing example 2 The alcohol component, carboxylic acid component, PET, esterification catalyst, and co-catalyst shown in Tables 1 and 3 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was held at 180°C for 1 hour under a nitrogen atmosphere, then the temperature was increased from 180°C to 235°C at a rate of 10°C / h, and polycondensation was carried out at 235°C for 5 hours. After that, the temperature was lowered to 210°C and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Tables 1 and 3 was reached to obtain amorphous polyester resins (resins AH6, AH7, resins AL6, AL7). The physical properties are shown in Tables 1 and 3.

[0087] Resin manufacturing example 3 The alcohol components, carboxylic acid components other than trimellitic anhydride and fumaric acid shown in Table 2, PET, esterification catalyst, and co-catalyst were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and trimellitic anhydride, fumaric acid, and polymerization inhibitor shown in Table 2 were added. The mixture was reacted at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at 10°C / h, and polycondensation was further carried out at 210°C for 1 hour. After that, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached to obtain amorphous polyester resin (resin AH9). The physical properties are shown in Table 2.

[0088] Resin manufacturing example 4 The alcohol components, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C, trimellitic anhydride as shown in Table 2 was added, and the mixture was reacted at 210°C for 1 hour. The reaction was then carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding an amorphous polyester resin (resin AH14). The physical properties are shown in Table 2.

[0089] Resin manufacturing example 5 The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 2 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the mixture was held at 180°C for 1 hour, then the temperature was increased from 180°C to 235°C at a rate of 10°C / h, and polycondensation was carried out at 235°C for 5 hours. After that, the temperature was reduced to 210°C, trimellitic anhydride as shown in Table 2 was added, and the reaction was carried out at 210°C for 1 hour. Then, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, yielding an amorphous polyester resin (resin AH15). The physical properties are shown in Table 2.

[0090] Resin manufacturing example 6 The alcohol component, carboxylic acid component, PET, esterification catalyst, and co-catalyst shown in Tables 3 and 4 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Tables 3 and 4 was reached to obtain amorphous polyester resins (resins AL1-AL5, AL8, AL10-AL13). The physical properties are shown in Tables 3 and 4.

[0091] Resin manufacturing example 7 The alcohol component, carboxylic acid component other than fumaric acid, PET, esterification catalyst, and co-catalyst shown in Table 4 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 4 were added. The mixture was reacted at 180°C for 1 hour, then the temperature was raised from 180°C to 210°C at a rate of 10°C / h, and polycondensation was further carried out at 210°C for 1 hour. After that, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in Table 4 was reached to obtain amorphous polyester resin (resin AL9). The physical properties are shown in Table 4.

[0092] Resin manufacturing example 8 The alcohol component, carboxylic acid component, esterification catalyst, and co-catalyst shown in Table 4 were placed in a 10-liter four-necked flask equipped with a drop-flow condenser with a nitrogen inlet tube and a dehydration tube, a stirrer, and a thermocouple. The mixture was heated to 235°C under a nitrogen atmosphere and then polycondensed at 235°C for 6 hours. After that, the temperature was lowered to 210°C and the reaction was carried out under reduced pressure of 10 kPa until the softening point shown in Table 4 was reached to obtain amorphous polyester resin (resin AL14). The physical properties are shown in Table 4.

[0093] Resin manufacturing example 9 The alcohol component, carboxylic acid component, esterification catalyst, and co-catalyst shown in Table 4 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. The mixture was held at 180°C for 1 hour under a nitrogen atmosphere, then the temperature was increased from 180°C to 235°C at a rate of 10°C / h, and then polycondensation was carried out at 235°C for 5 hours. Furthermore, the reaction was carried out at 235°C under reduced pressure of 10 kPa until the softening point shown in Table 4 was reached to obtain an amorphous polyester resin (resin AL15). The physical properties are shown in Table 4.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] Resin manufacturing example 10 In a 10-liter four-necked flask equipped with a drop-flow condenser having a nitrogen inlet tube and a dehydration tube, a stirrer, and a thermocouple, 3288 g of 1,6-hexanediol and 5712 g of sebacic acid were added and heated to 140°C for 6 hours. The reaction was then continued while increasing the temperature to 200°C at a rate of 10°C / h. After reacting at 200°C for 1 hour, 18 g of tin(II) 2-ethylhexanoate was added as an esterification catalyst, and the reaction was continued at 200°C for another 2 hours. The reaction was further carried out at 8 kPa for another 2 hours to obtain a crystalline polyester resin (resin C1). The softening point of resin C1 was 80.5°C, the melting point was 68.7°C, and the crystallinity index was 1.2.

[0099] Examples of Ketimine Compound Production In a 1-liter four-necked separable flask equipped with a stirrer and thermometer, 170 parts by mass of isophorone diamine and 75 parts by mass of methyl ethyl ketone were charged, and the reaction was carried out at 50°C for 5 hours to obtain ketimine compound K1. The amine value of ketimine compound K1 was 418 mgKOH / g.

[0100] Resin manufacturing example 11 In a 10-liter four-necked flask equipped with a drop-flow condenser having a nitrogen inlet tube and a dehydration tube, a stirrer, and a thermocouple, 2954 g of 3-methyl-1,5-pentanediol, 1697 g of isophthalic acid, and 1825 g of adipic acid were added. After heating to 100°C, 97 g of trimethylolpropane and 6.6 g of titanium tetraisopropoxide as an esterification catalyst were added together. Next, the temperature was raised to 200°C over approximately 4 hours, then to 230°C over 2 hours, and polycondensation was carried out at 230°C for 6 hours. Furthermore, the reaction was carried out under reduced pressure of 8 kPa for 7 hours to obtain a polyester resin containing hydroxyl groups. Next, 410 parts by mass of polyester resin having hydroxyl groups, 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate were placed in a 3-liter four-necked flask equipped with a nitrogen inlet tube, a fall-flow condenser, a stirrer, and a thermocouple. The mixture was then reacted at 100°C for 5 hours to obtain polyester resin b1 having isocyanate groups.

[0101] A 50% by mass ethyl acetate solution of the obtained polyester resin b1 having isocyanate groups was placed in a 3-liter four-necked flask equipped with a nitrogen inlet tube, a drop-through condenser, a stirrer, and a thermocouple. Ketimine compound K1 was added dropwise while stirring so that the equivalent ratio of isocyanate groups to amino groups (NCO groups / NH2 groups) was 1.0. After stirring at 45°C for 10 hours, the solution was dried under reduced pressure at 50°C under 10 kPa until the ethyl acetate content was 100 ppm or less, to obtain polyester resin B1. The glass transition temperature of resin B1 was -40°C.

[0102] Examples 1, 5-16, 19, Comparative Examples 1-2 [Melting kneading method] 100 parts by mass of the binder resin shown in Table 5, 100 parts by mass of titanium oxide "Typeque CR-50-2" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina treated, average number particle size: 250 nm), 3 parts by mass of the release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C), and 5 parts by mass of the charge control agent "FCA-2521-NJ" (manufactured by Fujikura Kasei Co., Ltd.) were mixed in a Henschel mixer.

[0103] The obtained mixture was melt-kneaded using a co-rotating twin-screw extruder with a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, at a screw rotation speed of 200 r / min and a barrel set temperature of 100°C to obtain a molten mixture. The mixture supply rate was 20 kg / h, and the average residence time was approximately 18 seconds.

[0104] The resulting molten mixture is cooled and coarsely ground, then ground in a jet mill, and classified using an air-flow classifier (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain the medium volume particle size (D 50 ) yielded toner particles with a size of 7.0 μm.

[0105] Toner was obtained by mixing 100 parts by mass of the obtained toner particles with 1 part by mass of "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, number average particle size: 16 nm) and 2 parts by mass of "RY-50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, number average particle size: 40 nm) as external additives in a Henschel mixer at a rotation speed of 3000 r / min (peripheral speed 32 m / sec) for 3 minutes.

[0106] Examples 2-4 Toner was obtained in the same manner as in Example 1, except that the amount of titanium dioxide "Typake CR-50-2" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina treated, average particle size: 250 nm) used was changed to the number of copies shown in Table 5.

[0107] Example 17 Toner was obtained in the same manner as in Example 1, except that a continuous two-roll open-roll mixer "Nidex" (manufactured by Nippon Coke Industries Co., Ltd.) was used for melt-mixing instead of a co-rotating twin-screw extruder. The continuous two-roll open-roll mixer had a roll outer diameter of 0.14 m and an effective roll length of 0.8 m. The operating conditions were a rotation speed of 75 r / min (peripheral speed 33 m / min) for the high-speed roll (front roll), a rotation speed of 50 r / min (peripheral speed 22 m / min) for the low-speed roll (rear roll), and a roll gap of 0.1 mm. The heating and cooling media temperatures inside the rolls were set to 140°C on the raw material input side and 110°C on the mixed material discharge side of the high-speed roll, and to 65°C on the raw material input side and 30°C on the mixed material discharge side of the low-speed roll. The raw material mixture supply rate was 10 kg / h, and the average residence time was approximately 5 minutes.

[0108] Example 18 [Emulsification and Coagulation Method] <Preparation of an aqueous dispersion of resin particles for cores> 600 g of methyl ethyl ketone was placed in a 5-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube. 150 g of resin AH1 was added at 60°C and dissolved. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a neutralization degree of 60 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Subsequently, 675 g of deionized water was added over 77 minutes. Then, while stirring at 250 r / min under reduced pressure at a temperature below 50°C, the methyl ethyl ketone and some of the water were distilled off. The solid content concentration of the aqueous dispersion was measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a resin dispersion for the core. The median particle size (D) of the resin particles in the dispersion was measured. 50 The wavelength was 200 nm, and the CV value was 24%.

[0109] <Preparation of aqueous dispersion of resin particles for shells> 600 g of methyl ethyl ketone was charged into a 5-liter container equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube. 150 g of resin AL1 was added at 60 °C and dissolved. To the resulting solution, an aqueous 5% by mass sodium hydroxide solution was added to a neutralization degree of 60 mol% with respect to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Subsequently, 675 g of deionized water was added over 77 minutes. Then, while stirring at 250 r / min, methyl ethyl ketone and a part of the water were distilled off under reduced pressure at a temperature of 50 °C or lower, and the solid content concentration of the aqueous dispersion was measured. The solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a resin dispersion for the shell. The volume median diameter (D 50 ) of the resin particles in the dispersion was 110 nm and the CV value was 20%.

[0110] <Preparation of Colorant Dispersion> 16.3 g (active ingredient 2.5 g) of an aqueous 15% by mass sodium dodecylbenzenesulfonate solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant, LAS), 120 g of titanium oxide "Ty-Pake CR-80" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina, silica-treated, number average particle diameter: 250 nm), 122.4 g of water, and zirconia beads with a diameter of 0.8 mm were added to a 2-liter metal container to a volume filling rate of 60% by volume, and using a 6-cylinder sand mill "TSG-6" (manufactured by Imex Co., Ltd.), dispersion was carried out at 25 °C for 4 hours at a rotation speed of 1300 r / min (peripheral speed 4.8 m / sec). The zirconia beads were removed using a mesh, and the solid content concentration of the aqueous dispersion was adjusted to 15% by mass with deionized water to obtain a colorant dispersion. The volume median diameter (D 50 ) of the colorant particles in the dispersion was 290 nm and the CV value was 33%.

[0111] <Preparation of Release Agent Dispersion> 50g of Fischer-Tropsch wax (manufactured by Nippon Seiro Co., Ltd., trade name: FNP0090, melting point: 90℃), 5g of cationic surfactant (manufactured by Kao Corporation, trade name: Sanizol B50), and 200g of deionized water were heated to 95℃, and the wax was dispersed using a homogenizer. After further dispersion treatment with a pressure-discharge type homogenizer, deionized water was added to obtain a release agent dispersion with a solid content of 20% by mass. The median particle size (D) of the release agent particles in the dispersion was measured. 50 The wavelength was 550nm, and the CV value was 26%.

[0112] <Preparation of toner particles> In a 3-liter four-necked flask equipped with a reflux condenser, a stirrer, and a thermocouple, 500 g of the core resin dispersion, 530 g of the coloring agent dispersion, 33 g of the mold release agent dispersion, and 3.3 g of 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant) were added and mixed at a temperature of 25°C. Next, while stirring the resulting mixture at 25°C, a solution prepared by dissolving 40 g of ammonium sulfate in 570 g of deionized water and adding a 4.8% by mass potassium hydroxide aqueous solution to adjust the pH to 8.2 was added dropwise over 10 minutes, and the temperature was raised to 62°C over 2 hours to determine the volume-median particle size (D) of the aggregated particles. 50 The mixture was maintained at 62°C until it reached a size of 6.9 μm, and a dispersion of aggregated particles (I) was obtained.

[0113] While maintaining the temperature of the dispersion of the obtained aggregated particles (I) at 62°C, 500 g of the shell resin dispersion was added dropwise at a rate of 0.6 mL / min (0.6 g / min) to obtain a dispersion of aggregated particles (II). The median volume particle size (D) of the aggregated particles (II) 50 The diameter was 7.0 μm.

[0114] To the dispersion of the obtained aggregated particles (II), an aqueous solution was added, which consisted of 20 g of polyoxyethylene lauryl ether sodium sulfate "Emal E-27C" (manufactured by Kao Corporation, anionic surfactant, effective concentration 27% by mass), 280 g of deionized water, and 40 g of 0.1 mol / L sulfuric acid aqueous solution. The mixture was then heated to 80°C over 1 hour, held at 80°C for 30 minutes, and then 10 g of 0.1 mol / L sulfuric acid aqueous solution was added, followed by a further 15 g of 0.1 mol / L sulfuric acid aqueous solution. The mixture was then held at 80°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles (core-shell particles) in which the aggregated particles had fused together.

[0115] The obtained core-shell particle dispersion was cooled to 30°C, and the dispersion was filtered by suction to separate the solid components. The dispersion was then washed with deionized water at 25°C and filtered by suction at 25°C for 2 hours. Subsequently, toner particles were obtained by vacuum drying at 33°C for 24 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC). The median particle size (D) of the obtained toner particles was measured. 50 The particle size was 7.0 μm, and the circularity was 0.970. The composition ratio (mass ratio) of the binder resin of the obtained toner particles was resin AH1 / resin AL1 = 50 / 50.

[0116] 100 parts by mass of the obtained toner particles were mixed with 1 part by mass of "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, number average particle size: 16 nm) and 2 parts by mass of "RY-50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, number average particle size: 40 nm) as external additives in a Henschel mixer at a rotation speed of 3000 r / min (peripheral speed 32 m / s) for 3 minutes to obtain toner.

[0117] Example 20 A toner was obtained in the same manner as in Example 1, except that 100 parts by mass of "Typake CR-80" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina, silica treated, number average particle size: 250 nm) was used as titanium dioxide instead of "Typake CR-50-2".

[0118] Example 21 A toner was obtained in the same manner as in Example 1, except that 100 parts by mass of "Typake CR-60-2" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina, organic matter treated, number average particle size: 210 nm) was used as titanium dioxide instead of "Typake CR-50-2".

[0119] Example 22 A toner was obtained in the same manner as in Example 1, except that instead of 50 parts by mass of resin AH1 and 50 parts by mass of resin AL1, 45 parts by mass of resin AH1, 45 parts by mass of resin AL1, and 10 parts by mass of resin C1 were used as the binder resin.

[0120] Example 23 [Dissolution and Suspension Method] <Preparation of crystalline polyester resin dispersion> 100g of resin C1 and 400g of ethyl acetate were placed in a 2-liter metal container, heated to 75°C to dissolve, and then rapidly cooled in an ice bath at a rate of 27°C / min. Glass beads with a diameter of 3 mm were added to achieve a volume filling rate of 60 vol%, and the mixture was ground for 4 hours at a rotation speed of 1300 r / min (peripheral speed 4.8 m / sec) using a 6-cylinder sand mill "TSG-6" (manufactured by AIMEX Co., Ltd.). The glass beads were removed using a mesh to obtain a crystalline polyester resin dispersion with a solid content concentration of 20% by mass.

[0121] <Preparation of oil phase I> 150 parts by mass of the release agent dispersion prepared in Example 18, 150 parts by mass of polyester resin B1, 500 parts by mass of crystalline polyester resin dispersion, 375 parts by mass of resin AH1, 375 parts by mass of resin AL1, and 2 parts by mass of ketimine compound K1 were placed in a container and mixed at 5,000 r / min for 60 minutes using a "TK Homo Mixer" (manufactured by Primix Co., Ltd.) to obtain oil phase I.

[0122] <Preparation of aqueous phase II> In a flask equipped with a stirrer and thermometer, 683 parts by mass of water, 11 parts by mass of "Eleminol RS-3000" (manufactured by Sanyo Chemical Industries, Ltd.), sodium salt of ethylene oxide adduct sulfate methacrylate, 138 parts by mass of styrene, 138 parts by mass of methacrylic acid, and 1 part by mass of ammonium persulfate were charged. The mixture was stirred at 400 r / min for 15 minutes, then the temperature was raised to 75°C and the mixture was allowed to react for 5 hours. Furthermore, 30 parts by mass of a 1% by mass aqueous solution of ammonium persulfate was added, and the mixture was aged at 75°C for 5 hours to obtain an aqueous dispersion of a polymeric dispersant (polymeric dispersant dispersion of styrene-methacrylic acid-sodium salt of ethylene oxide adduct sulfate methacrylate). The median particle size (D) of the polymeric dispersant in the dispersion was measured. 50 The wavelength was 140nm, and the CV value was 22%.

[0123] 990 parts by mass of water, 83 parts by mass of polymer dispersant dispersion, 38 parts by mass of 50% by mass aqueous solution of alkyldiphenyl ethersulfonate sodium "Perex SS-L" (manufactured by Kao Corporation), and 90 parts by mass of ethyl acetate were placed in a container and stirred to obtain a milky white aqueous phase II.

[0124] <Preparation of Emulsified Slurry III> To a container containing 776 parts by mass of oil phase I, 1333 parts by mass of the colorant dispersion prepared in Example 18 and 100 parts by mass of aqueous phase II were added. The mixture was then mixed for 20 minutes at 13,000 r / min using a "TK Homomixer" (manufactured by Primix Co., Ltd.) to obtain a dispersion slurry. The dispersion slurry was placed in a 3-liter four-necked flask equipped with a nitrogen inlet tube, a fall-flow condenser, a stirrer, and a thermocouple. The slurry was desolvated under reduced pressure of 20 kPa at 30°C for 8 hours, and then aged at 45°C for 4 hours to obtain emulsified slurry III.

[0125] <Preparation of toner particles> 100 parts by mass of the emulsified slurry III was filtered by suction to separate the solid components. The following operations (1) to (4) were repeated twice on the resulting filtered cake.

[0126] (1) 100 parts by mass of deionized water was added to the filtration cake and mixed at 12,000 r / min for 10 minutes using a "TK Homomixer" (manufactured by Primix Co., Ltd.), and then filtered by suction. (2) 100 parts by mass of 10% sodium hydroxide aqueous solution was added to the filtration cake from (1), and the mixture was mixed at 12,000 r / min for 30 minutes using a "TK Homomixer" (manufactured by Primix Co., Ltd.), and then filtered by suction. (3) 100 parts by mass of 10% hydrochloric acid was added to the filtration cake from (2), and the mixture was mixed at 12,000 r / min for 10 minutes using a "TK Homomixer" (manufactured by Primix Co., Ltd.), and then filtered by suction. (4) 300 parts by mass of deionized water were added to the filtration cake from (3), and the mixture was mixed at 12,000 r / min for 10 minutes using a "TK Homomixer" (manufactured by Primix Co., Ltd.), and then filtered by suction.

[0127] The obtained filtration cake was dried at 45°C for 48 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC), and then sieved through a mesh with a mesh opening of 75 μm to obtain toner particles. The median particle size (D) of the obtained toner particles was determined. 50 The diameter was 7.0 μm.

[0128] 100 parts by mass of the obtained toner particles were mixed with 1 part by mass of "Aerosil R-972" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: DMDS, number average particle size: 16 nm) and 2 parts by mass of "RY-50" (hydrophobic silica, manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil, number average particle size: 40 nm) as external additives in a Henschel mixer at a rotation speed of 3000 r / min (peripheral speed 32 m / s) for 3 minutes to obtain toner.

[0129] Test example [Weather resistance of printed materials] White toner was installed in the non-magnetic single-component developer "COREFIDO C712dnw" (manufactured by OKI Electric Industry Co., Ltd.), and the toner adhesion amount was 0.40 mg / cm². 2The resulting solid image was printed on 90kg paper (Kishu colored high-quality paper, thick, black) without being fixed. Furthermore, the fuser of the "COREFIDO C712dnw" (manufactured by OKI Electric Industry Co., Ltd.) was modified into an external fuser with a fixing speed of 100mm / sec, and the fixing temperature was set to 170℃ to fix the unfixed image.

[0130] The obtained fixed images were subjected to weather resistance testing using a xenon weatherometer under the following conditions.

[0131] • Irradiation test machine: SX75, manufactured by Suga Test Machine Co., Ltd. • Light source: Xenon lamp Filter: Inner = Quartz filter, Outer = #275 Panel temperature: 50℃ ·Battle humidity: 35~50%RH ·Irradiation intensity: 50 (W / m 2 ), measured values ​​at 300-400 (nm) • Cumulative illuminance: 40,000 (kJ / m 2 ), integrated value at 300-400 (nm)

[0132] Using a SpectroEye colorimeter (manufactured by X-Rite, lighting conditions: standard light source D50, observation field of view 2°, density reference DINNB, absolute white reference), the values ​​measured at three arbitrary points on the image were averaged, and the hue change (ΔE) was calculated based on the following formula. The results are shown in Tables 5 and 6. A smaller hue change ΔE indicates better weather resistance.

[0133] ΔE=[(L * 1-L * 2) 2 +(a * 1-a * 2) 2 +(b * 1-b * 2) 2 ] 1 / 2 L * 1, a * 1, b * 1: L before irradiation * a * b * value L* 2, a * 2, b * 2: L after irradiation * a * b * value

[0134] [Table 5]

[0135] [Table 6]

[0136] Based on these results, it can be seen that the white toners of Examples 1 to 23 have good weather resistance compared to Comparative Examples 1 and 2, which used polyester resins that did not contain PET or polyester resins that used ethylene glycol and terephthalic acid instead of PET. [Industrial applicability]

[0137] The electrostatic image developing white toner of the present invention is suitably used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims

1. A white toner for developing electrostatic images, comprising a binder resin containing amorphous polyester resin A and titanium dioxide, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate.

2. The electrostatic image developing white toner according to claim 1, wherein the polyethylene terephthalate content is 5 mol% or more and 75 mol% or less of the total amount of alcohol component, carboxylic acid component and polyethylene terephthalate, with terephthalate-ethylene glycol units considered as 1 mole.

3. The electrostatic image developing white toner according to claim 1 or 2, wherein the IV value of polyethylene terephthalate is 0.40 or more and 0.85 or less.

4. The white toner for electrostatic image development according to claim 1 or 2, wherein the titanium dioxide content is 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of amorphous polyester resin A.

5. The white toner for electrostatic image development according to claim 1 or 2, wherein the number-average particle size of titanium dioxide is 150 nm or more and 350 nm or less.

6. The white toner for electrostatic image development according to claim 1 or 2, wherein the binder resin content is 30% by mass or more and 83% by mass or less.

7. The electrostatic image developing white toner according to claim 1 or 2, wherein the content of amorphous polyester resin A is 40% by mass or more in the binder resin.

8. The white toner for electrostatic image development according to claim 1 or 2, wherein the softening point of the amorphous polyester resin A is 70°C or higher and 170°C or lower.

9. The white toner for electrostatic image development according to claim 1 or 2, wherein the binder resin contains two resins having different softening points with a difference of 10°C or more, and at least one of the two resins is amorphous polyester resin A.

10. The white toner for electrostatic image development according to claim 9, wherein the softening point of the resin with the higher softening point is 100°C or higher and 170°C or lower.

11. The white toner for electrostatic image development according to claim 9, wherein the softening point of the resin with the lower softening point is 70°C or higher and 130°C or lower.

12. The white toner for electrostatic image development according to claim 9, wherein the mass ratio of the resin with the higher softening point to the resin with the lower softening point is 10 / 90 or more and 90 / 10 or less.

Images