White toner for electrostatic image development

Abstract

The present invention provides a white toner for electrostatic image development containing: a binder resin containing an amorphous polyester resin A; and titanium oxide. The amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. This white toner for electrostatic image development is suitable for use in, for example, developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, or the like.

Description

White toner for electrostatic image development

[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.

[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).

[0004] Japanese Patent Publication No. 2023-173361 Japanese Patent Publication No. 2023-88255

[0005] 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. Detailed description of the invention

[0006] 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.

[0007] This invention relates to a white toner for electrostatic image development that has excellent weather resistance.

[0008] The electrostatic image developing white toner of the present invention exhibits excellent weather resistance.

[0009] The electrostatic image developing white toner of the present invention is characterized by containing titanium dioxide as a white coloring agent and amorphous polyester resin A, which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (hereinafter referred to as "PET"). The reason why the effects of the present invention are achieved is not clear, but it is presumed to be as follows. Note that the following mechanism is a hypothesis and is not limited thereto.

[0010] In the present invention, the weather resistance of printed matter is improved by using a polycondensate (amorphous polyester resin A) of an alcohol component, a carboxylic acid component, and PET. 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 presumably because titanium oxide is stabilized from ultraviolet rays, the weather resistance of the printed matter is considered to be improved.

[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 is a bisphenol A alkylene oxide adduct represented by the formula (I):

[0013]

[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, and are each a positive number. The sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less). It is preferable to contain an alkylene oxide adduct of bisphenol A represented by the formula (I). Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. It is preferable to use one or more of these.

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

[0016] Examples of other alcohol components include aliphatic diols and alcohols with three or more hydroxyl groups.

[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, neopentyl glycol, and the like.

[0018] Examples of alcohols with three or more hydroxyl groups include glycerin, trimethylolpropane, pentaerythritol, and the like.

[0019] From the perspective of hot offset resistance, the carboxylic acid component preferably contains an aromatic dicarboxylic acid-based compound.

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

[0021] The content of the aromatic dicarboxylic acid-based compound in the carboxylic acid component is preferably 35 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more, and even more preferably 50 mol% or more, and is 100 mol% or less. When the carboxylic acid component contains a carboxylic acid-based compound with three or more hydroxyl groups, it is preferably 90 mol% or less, more preferably 85 mol% or less. However, the terephthalic acid unit contained in PET is not included in the carboxylic acid component here.

[0022] Examples of other carboxylic acid components include aliphatic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, and sebacic acid, carboxylic acids with three or more hydroxyl groups such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 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-based 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 used as raw material monomers in the polycondensation reaction and incorporated into the polyester resin.

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

[0027] In the present 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 the 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] Examples of commercially available PET products with an IV value of 0.40 to 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, of the total amount of alcohol component, carboxylic acid component, and PET, from the viewpoint of weather resistance. Since PET is an equimolar polycondensate of ethylene glycol and terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is calculated 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 is taken 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, based on 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, based on 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 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]. Amorphous resins are those in which no endothermic peak is observed, or, if observed, resins 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, crystalline resins are those with 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, and 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 more 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 resins with different softening points, from the viewpoint of low-temperature fixability and fixation width. The difference in softening points between the two 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 without using 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 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 that has been surface-treated is preferred. 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 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 (binding agent) 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 low-temperature fixing performance and hot offset resistance of the toner, as well as 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 a tertiary amine as a side chain; and 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, negative charge control agents include polymer types such as "FCA-2521NJ" (manufactured by Fujikura Chemical Co., Ltd.); 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.); and benzyl Examples include metal compounds of salicylic acid compounds, such as "LR-147" and "LR-297" (both manufactured by Nippon Carlit Co., Ltd.); metal compounds of salicylic acid compounds, such as "Bontron E-81," "Bontron E-84," "Bontron E-88," and "Bontron E-304" (all manufactured by Orient Chemical Industries, Ltd.), and "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.); copper phthalocyanine dyes; quaternary ammonium salts, such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives, etc.; and organometallic compounds.

[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 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 for hydrophobicizing 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.

[0071] With regard to the embodiments described above, the present invention further discloses the following electrostatic image developing white toner and a method for manufacturing the white toner.

[0072] <1> A white toner for developing electrostatic images, comprising a binder resin 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.

[0073] <2> The white toner for electrostatic image development according to <1>, wherein the alcohol component contains an alkylene oxide adduct of bisphenol A represented by formula (I). <3> The white toner for electrostatic image development according to <2>, wherein the content of the alkylene oxide adduct of bisphenol A represented by formula (I) is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and 100 mol% or less, in the alcohol component. <4> The white toner for electrostatic image development according to any one of <1> to <3>, wherein the carboxylic acid component contains an aromatic dicarboxylic acid compound. <5> The white toner for electrostatic image development according to <4>, wherein the content of the aromatic dicarboxylic acid compound is 35 mol% or more, preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, and 100 mol% or less, in the carboxylic acid component, preferably 90 mol% or less, and more preferably 85 mol% or less. <6> A white toner for developing electrostatic images according to any of <1> to <5> above, wherein the IV value of polyethylene terephthalate is 0.40 or higher, preferably 0.45 or higher, more preferably 0.50 or higher, even more preferably 0.55 or higher, and 0.85 or lower, preferably 0.80 or lower, more preferably 0.75 or lower, even more preferably 0.70 or lower, and even more preferably 0.65 or lower. <7> A white toner for developing electrostatic images according to any one of <1> to <6> above, wherein the IV value of polyethylene terephthalate is 0.40 or higher, preferably 0.45 or higher, more preferably 0.50 or higher, even more preferably 0.55 or higher, and 0.85 or lower, preferably 0.80 or lower, more preferably 0.75 or lower, even more preferably 0.70 or lower, and even more preferably 0.65 or lower, and the content of polyethylene terephthalate is 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and 100% by mass or less, of the total amount of polyethylene terephthalate subjected to polycondensation.<8> The electrostatic image developing white toner according to any one of <1> to <7> above, wherein the polyethylene terephthalate content is 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, 75 mol% or less, preferably 70 mol% or less, and more preferably 60 mol% or less, based on 1 mole of terephthalate-ethylene glycol units, in the total amount of alcohol component, carboxylic acid component, and polyethylene terephthalate. <9> The electrostatic image developing white toner according to any one of <1> to <8> above, wherein the softening point of amorphous polyester resin A is 70°C or higher, preferably 90°C or higher, more preferably 100°C or higher, 170°C or lower, preferably 160°C or lower, and more preferably 150°C or lower. <10> The electrostatic image developing white toner according to any one of <1> to <9> above, wherein the glass transition temperature of amorphous polyester resin A is 40°C or higher, preferably 50°C or higher, 80°C or lower, and preferably 70°C or lower. <11> The electrostatic image developing white toner according to any of <1> to <10> above, wherein the content of amorphous polyester resin A in the binder resin is 40% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less. <12> The electrostatic image developing white toner according to any of <1> to <11> above, wherein the content of polyethylene terephthalate in the binder resin is 2 mol% or more, preferably 4 mol% or more, more preferably 8 mol% or more, and 75 mol% or less, preferably 70 mol% or less, and more preferably 60 mol% or less. <13> A white toner for developing electrostatic images according to any one of <1> to <12>, wherein the binder resin contains two types of resins having different softening points, at least one of the two types of resins is amorphous polyester resin A, and the difference in softening points of the two types of resins is 10°C or more, preferably 20°C or more, and 60°C or less, preferably 40°C or less.<14> The white toner for electrostatic image development according to <13>, wherein the softening point of the resin with the higher softening point is 100°C or higher, preferably 110°C or higher, more preferably 120°C or higher, and 170°C or lower, preferably 160°C or lower, and more preferably 150°C or lower. <15> The white toner for electrostatic image development according to <13> or <14>, wherein the softening point of the resin with the lower softening point is 70°C or higher, preferably 90°C or higher, more preferably 100°C or higher, and 130°C or lower, preferably 125°C or lower, and more preferably 120°C or lower. <16> The white toner for electrostatic image development according to any of <13> to <15>, 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, preferably 20 / 80 or more, more preferably 30 / 70 or more, even more preferably 40 / 60 or more, and 90 / 10 or less, preferably 80 / 20 or less, more preferably 70 / 30 or less, and even more preferably 60 / 40 or less. <17> The white toner for electrostatic image development according to any of <1> to <16>, wherein the binder resin content in the toner is 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, and 83% by mass or less, preferably 80% by mass or less, and even more preferably 75% by mass or less. <18> The white toner for electrostatic image development according to any of <1> to <17>, wherein the crystal form of titanium oxide is anatase type, rutile type, or brookite type. <19> The white toner for developing electrostatic images according to any one of <1> to <18> above, wherein the titanium dioxide is titanium dioxide surface-treated with an inorganic substance, preferably titanium dioxide surface-treated with at least one of silica and alumina. <20> The white toner for developing electrostatic images according to any one of <1> to <19> above, wherein the number-average particle diameter of the titanium dioxide is 150 nm or more, preferably 200 nm or more, more preferably 230 nm or more, and 350 nm or less, preferably 300 nm or less, more preferably 270 nm or less.<21> A white toner for electrostatic image development according to any one of <1> to <20>, wherein the titanium dioxide content is 20 parts by mass or more, preferably 35 parts by mass or more, more preferably 60 parts by mass or more, and 150 parts by mass or less, preferably 135 parts by mass or less, and more preferably 115 parts by mass or less, per 100 parts by mass of amorphous polyester resin A. <22> A white toner for electrostatic image development according to any one of <1> to <21>, which is a pulverized toner. <23> A method for producing a white toner for electrostatic image development according to any one of <1> to <21>, comprising the steps of melting and kneading raw materials containing amorphous polyester resin A and titanium dioxide, and pulverizing the resulting kneaded product.

[0074] 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.

[0075] [IV value of PET] Dissolve 4 g / L in a mixed solvent of phenol / tetrachloroethane in a 60 / 40 (mass ratio) solution, measure with an Ubbelohde viscometer, and calculate from the following formula: IV = (-1 + √(1 + 4kη)) / (2kC) [wherein k = 0.33, C = 0.004 g / mL, and η = (t １ / t ０ ) - 1 (t ０ : Number of seconds for the solvent to fall, t １ This is the number of seconds it takes for the sample solution to fall.

[0076] [Amine value of ketimine compounds] Measured according to the method of JIS K2501:2003. However, the measurement solvent is changed from chlorobenzene to chloroform as specified in JIS K2501:2003.

[0077] [Resin Softening Point] 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 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 the temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0078] [Maximum Endothermic Peak Temperature of 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.

[0079] [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 line below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the peak apex is defined as the glass transition temperature.

[0080] [Acid Value of Resins] The acid value of resins shall be measured according to the method of JIS K 0070:1992. However, the measurement solvent shall be changed from the ethanol and ether mixed solvent specified in JIS K 0070 to an acetone and toluene mixed solvent (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to a chloroform and dimethylformamide mixed solvent (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0081] [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 diameters) of 100 particles (primary particles) using a scanning electron microscope (SEM) at an appropriate magnification of 5,000 to 50,000 times, and the average value of these measurements is taken as the number-average particle size of titanium dioxide, silica particles, and external additives.

[0082] [Melting Point of Release Agent] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), weigh 0.02 g of the sample into an aluminum pan, heat it up to 200 °C, and then cool it from 200 °C to 0 °C at a cooling rate of 10 °C / min. Next, heat the sample at a heating rate of 10 °C / min and measure the heat quantity. The maximum peak temperature of the endotherm is taken as the melting point.

[0083] [Volume Median Diameter and CV Value of Resin Particles, Colorant Particles, Release Agent Particles, and Polymer Dispersant] (1) Measuring Device: Laser Diffraction Particle Size Analyzer "LA-920" (manufactured by Horiba, Ltd.) (2) Measuring Conditions: Take the sample dispersion liquid in the measuring cell, add distilled water, and measure the volume median diameter (D ５０ ) and the volume average diameter at a temperature where the absorbance is within the appropriate range. The CV value is calculated according to the following formula. CV value (%) = (standard deviation of particle size distribution / volume average diameter) × 100

[0084] [Solid Content Concentration of Resin Dispersion Liquid, Colorant Dispersion Liquid, and Release Agent Dispersion Liquid] Using an infrared moisture meter "FD-230" (manufactured by Kett Scientific Co., Ltd.), dry 5 g of the measurement sample at a drying temperature of 150 °C and a measurement mode of 96 (monitoring time 2.5 minutes, fluctuation range 0.05%) to measure the moisture content (mass%) of the dispersion liquid. The solid content concentration is calculated according to the following formula. Solid content concentration (mass%) = 100 - moisture content (mass%)

[0085] [Volume Median Diameter of Aggregated Particles] - Measuring Machine: "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.) - Measuring Conditions: Adjust the concentration of the sample dispersion liquid by adding it to 100 mL of the above electrolyte so that the particle sizes of 30,000 particles can be measured in 20 seconds. Then measure 30,000 particles and obtain the volume median diameter (D ５０ ) from the particle size distribution.

[0086] [Volume Median Diameter (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: Polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] dissolved in the electrolyte and adjusted to 5% by mass ・Dispersion conditions: 10 mg of the sample to be measured is added to 5 mL of the dispersion, dispersed for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80 W), then 25 mL of the electrolyte is added, and dispersed 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 median particle size (D) is determined from the particle size distribution. ５０ )

[0087] [Toner Circularity] The circularity of toner particles is measured under the following conditions: • Measuring device: Flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) • Dispersion preparation: The toner particle dispersion is prepared by diluting it with deionized water to a solid content concentration of 0.001 to 0.05% by mass. • Measurement mode: HPF measurement mode

[0088] Resin Production Example 1 The alcohol component, carboxylic acid component 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 having 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, 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 to obtain amorphous polyester resins (resins AH1 to AH5, AH8, AH10 to AH13). The physical properties are shown in Tables 1 and 2.

[0089] Resin Production 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 having a nitrogen inlet tube and a 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.

[0090] Resin Production Example 3 As shown in Table 2, the alcohol component, carboxylic acid components other than trimellitic anhydride and fumaric acid, 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 as 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.

[0091] Resin Production Example 4: 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 drop-flow condenser having 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, trimellitic anhydride 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.

[0092] Resin Production Example 5 As shown in Table 2, the alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and co-catalyst 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 lowered 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, to obtain amorphous polyester resin (resin AH15). The physical properties are shown in Table 2.

[0093] Resin Production 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 having 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 Tables 3 and 4 was reached to obtain amorphous polyester resins (resins AL1 to AL5, AL8, AL10 to AL13). The physical properties are shown in Tables 3 and 4.

[0094] Resin Production Example 7 As shown in Table 4, the alcohol component, carboxylic acid component other than fumaric acid, PET, esterification catalyst, and co-catalyst were placed 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. 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 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.

[0095] Resin Production 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 nitrogen inlet tube, a fall-flow condenser with 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.

[0096] Resin Production 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.

[0097]

[0098]

[0099]

[0100]

[0101] Resin Production Example 10 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 was placed in a flask. 3288 g of 1,6-hexanediol and 5712 g of sebacic acid were added and heated to 140°C for 6 hours. The mixture was then heated to 200°C at a rate of 10°C / h while continuing the reaction. 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 then 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.

[0102] Preparation Example of Ketimine Compound: 170 parts by mass of isophorone diamine and 75 parts by mass of methyl ethyl ketone were charged into a 1-liter four-necked separable flask equipped with a stirrer and thermometer, 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.

[0103] Resin Production Example 11 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 was added to 2954 g of 3-methyl-1,5-pentanediol, 1697 g of isophthalic acid, and 1825 g of adipic acid. The mixture was heated to 100°C, and then 97 g of trimethylolpropane and 6.6 g of titanium tetraisopropoxide as an esterification catalyst were added together. Next, the mixture was heated to 200°C in about 4 hours, then to 230°C in 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 having 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.

[0104] A 50% by mass ethyl acetate solution of the obtained polyester resin b1 having isocyanate groups is placed in a 3-liter four-necked flask equipped with a nitrogen inlet tube, a fall-flow condenser, a stirrer, and a thermocouple, and while stirring, the equivalent ratio of isocyanate groups to amino groups (NCO groups / NH) is calculated. ２ Ketimine compound K1 was added dropwise until the ratio of the base was 1.0. After stirring at 45°C for 10 hours, the mixture was dried under reduced pressure of 10 kPa at 50°C 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.

[0105] Examples 1, 5-16, 19, Comparative Examples 1-2 [Melting Mixing 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.

[0106] 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.

[0107] 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 This yielded toner particles with a diameter of 7.0 μm.

[0108] 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.

[0109] 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, number average particle size: 250 nm) used was changed to the number shown in Table 5.

[0110] 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.

[0111] Example 18 [Emulsification and Aggregation Method] <Preparation of Aqueous Dispersion of Core Resin Particles> 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 obtained 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, the methyl ethyl ketone and some of the water were distilled off at a temperature of 50°C or lower. The solid content concentration of the aqueous dispersion was then measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a core resin dispersion. Volume median particle size (D) of resin particles in the dispersion. ５０ The wavelength was 200 nm, and the CV value was 24%.

[0112] <Preparation of Aqueous Dispersion of Shell Resin Particles> 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 AL1 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, the methyl ethyl ketone and some of the water were removed at a temperature of 50°C or lower. The solid content concentration of the aqueous dispersion was then measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain the shell resin dispersion. Volume median particle size (D) of resin particles in the dispersion. ５０ The wavelength was 110 nm, and the CV value was 20%.

[0113] <Preparation of Colorant Dispersion> In a 2-liter metal container, 16.3 g (2.5 g effective content) of 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant, LAS), 120 g of titanium dioxide "Typake CR-80" (manufactured by Ishihara Sangyo Co., Ltd., rutile type, alumina, silica treated, number average particle size: 250 nm), 122.4 g of water, and zirconia beads with a diameter of 0.8 mm were added to achieve a volume filling rate of 60 vol%. Dispersion was carried out at 25°C for 4 hours using a 6-cylinder sand mill "TSG-6" (manufactured by AIMEX Co., Ltd.) 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 the colorant dispersion. The median particle size (D) of colorant particles in the dispersion. ５０ The wavelength was 290 nm, and the CV value was 33%.

[0114] <Preparation of Release Agent Dispersion> 50 g of Fischer-Tropsch wax (manufactured by Nippon Seiro Co., Ltd., trade name: FNP0090, melting point: 90°C), 5 g of cationic surfactant (manufactured by Kao Corporation, trade name: Sanizol B50), and 200 g of deionized water were heated to 95°C. The wax was dispersed using a homogenizer, then dispersed again using a pressure-discharge homogenizer, and 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 550 nm, and the CV value was 26%.

[0115] <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.

[0116] 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.

[0117] 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.

[0118] 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 volume particle size (D) of the obtained toner particles was determined. 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.

[0119] 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 / s) for 3 minutes.

[0120] Example 20 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 instead of "Typake CR-50-2" as titanium dioxide.

[0121] Example 21 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".

[0122] Example 22 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.

[0123] Example 23 [Dissolution and Suspension Method] <Preparation of Crystalline Polyester Resin Dispersion> 100 g of resin C1 and 400 g of ethyl acetate were placed in a 2-liter metal container and heated to 75°C to dissolve. After that, it was 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 of 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.

[0124] <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.

[0125] <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.), 138 parts by mass of styrene, 138 parts by mass of methacrylic acid, and 1 part by mass of ammonium persulfate were charged. After stirring at 400 r / min for 15 minutes, the temperature was raised to 75°C and the mixture was reacted 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 methacrylate adduct sulfate. The median particle size (D) of the polymeric dispersant in the dispersion was measured. ５０ The wavelength was 140 nm, and the CV value was 22%.

[0126] 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.

[0127] <Preparation of Emulsified Slurry III> 1333 parts by mass of the colorant dispersion prepared in Example 18 and 100 parts by mass of aqueous phase II were added to a container containing 776 parts by mass of oil phase I. The mixture was then mixed at 13,000 r / min for 20 minutes using a "TK Homomixer" (manufactured by Primix Co., Ltd.) to obtain a dispersed slurry. The dispersed 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 solvent was removed 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.

[0128] <Preparation of Toner Particles> 100 parts by mass of 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.

[0129] (1) Add 100 parts by mass of deionized water to the filtration cake and mix at 12,000 r / min for 10 minutes using a "TK Homo Mixer" (manufactured by Primix Co., Ltd.), then filter by suction. (2) Add 100 parts by mass of 10% sodium hydroxide aqueous solution to the filtration cake from (1) and mix at 12,000 r / min for 30 minutes using a "TK Homo Mixer" (manufactured by Primix Co., Ltd.), then filter by suction. (3) Add 100 parts by mass of 10% hydrochloric acid to the filtration cake from (2) and mix at 12,000 r / min for 10 minutes using a "TK Homo Mixer" (manufactured by Primix Co., Ltd.), then filter by suction. (4) Add 300 parts by mass of deionized water to the filtration cake from (3) and mix at 12,000 r / min for 10 minutes using a "TK Homo Mixer" (manufactured by Primix Co., Ltd.), then filter by suction.

[0130] 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 volume particle size (D) of the obtained toner particles was determined. ５０ The diameter was 7.0 μm.

[0131] 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 / s) for 3 minutes.

[0132] Test Example [Weather Resistance of Printed Materials] White toner was mounted on a non-magnetic single-component developer "COREFIDO C712dnw" (manufactured by OKI Electric Industry Co., Ltd.), and the toner adhesion amount was 0.40 mg / cm². ２ The 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 100 mm / sec, and the fixing temperature was set to 170°C to fix the unfixed image.

[0133] The obtained fixed images were subjected to weather resistance testing using a xenon weatherometer under the following conditions.

[0134] • Irradiation test machine: SX75, manufactured by Suga Test Instruments Co., Ltd. • Light source: Xenon lamp • Filter: Inner = Quartz filter, Outer = #275 • Panel temperature: 50°C • Chamber humidity: 35-50% RH • Irradiation intensity: 50 (W / m) ２ ), measured value and cumulative illuminance at 300-400 (nm): 40,000 (kJ / m ２ ), integrated value at 300-400 (nm)

[0135] 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. The smaller the hue change ΔE, the better the weather resistance.

[0136] ΔE = [(L ＊ １ -L ＊ ２ ) ２ + (a ＊ １ -a ＊ ２ ) ２ + (b ＊ １ -b ＊ ２ ) ２ ] １／２ L ＊ １ a ＊ １ , b ＊ １ : Before irradiation L ＊ a ＊ b ＊ Value L ＊ ２ a ＊ ２ , b ＊ ２ :L after irradiation ＊ a ＊ b ＊ value

[0137]

[0138]

[0139] 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 use PET or polyester resins that used ethylene glycol and terephthalic acid instead of PET.

[0140] 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 electrostatic image development containing an amorphous polyester resin A and a binder resin 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 any one of claims 1 to 3, 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. A white toner for developing electrostatic images according to any one of claims 1 to 4, wherein the number-average particle size of titanium dioxide is 150 nm or more and 350 nm or less.

6. A white toner for developing electrostatic images according to any one of claims 1 to 5, wherein the content of the binder resin is 30% by mass or more and 83% by mass or less.

7. The white toner for electrostatic image development according to any one of claims 1 to 6, 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 any one of claims 1 to 7, wherein the softening point of amorphous polyester resin A is 70°C or higher and 170°C or lower.

9. The white toner for electrostatic image development according to any one of claims 1 to 8, 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 or 10, 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 any one of claims 9 to 11, 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