Toner for developing electrostatic images

Abstract

This invention relates to a toner for electrostatic image development that has excellent resistance to hot offsetting and durability, and a method for manufacturing the same. [Solution] A toner for electrostatic image development containing amorphous polyester resin A and a release agent, and an external additive, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the median particle size (D) is determined based on the particle size distribution of the toner particle base particles. 50 ) is 3.0 μm or more and 10.0 μm or less, and from 0 μm to (D 50 A toner for developing electrostatic images and a method for manufacturing the same, wherein the proportion of particles up to -2.0 μm is 9.5% or less.

Description

[Technical Field]

[0001] The present invention relates to an electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like, and a method for manufacturing the same. [Background technology]

[0002] From the perspective of improving offset resistance and durability, toners containing polyester resin using polyethylene terephthalate as the binder resin are being considered.

[0003] Patent Document 1 discloses a toner for developing electrostatic images, wherein the binder resin contains two types of resins having softening points that differ by 10°C or more, and the resin with the higher softening point is a polyester obtained by reacting polyethylene terephthalate or modified polyethylene terephthalate with an alcohol component and a carboxylic acid component, or a hybrid resin having the polyester as one of the resin components. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-280084 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, there is a need to achieve both resistance to hot offset and durability, as well as further improvements in these aspects.

[0006] The present invention relates to a toner for electrostatic image development that has excellent resistance to hot offset and durability, and a method for manufacturing the same. [Means for solving the problem]

[0007] The present invention [1] A toner for electrostatic image development containing amorphous polyester resin A and a release agent, and an external additive, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the median particle size (D) is determined based on the particle size distribution of the toner mother particles. 50 ) is 3.0 μm or more and 10.0 μm or less, and from 0 μm to (D 50 A toner for developing electrostatic images in which the proportion of particles up to -2.0) μm is 9.5% or less, and [2] A method for producing electrostatic image developing toner according to [1], comprising the steps of: melting and kneading a mixture containing amorphous polyester resin A and a mold release agent; crushing and classifying the resulting mixture to obtain toner base particles; and mixing the obtained toner base particles with an external additive. Regarding. [Effects of the Invention]

[0008] The electrostatic image developing toner of the present invention exhibits excellent effects in terms of resistance to hot offset and durability. [Modes for carrying out the invention]

[0009] The electrostatic image developing toner of the present invention contains toner matrix particles and an external additive, which are composed of amorphous polyester resin A, a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (PET), and a mold release agent, and the toner matrix particles have a specific particle size distribution. 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 mechanism described below is a hypothesis and is not limited thereto.

[0010] This invention reduces the small particle size component of toner particles. Since small particle size components tend to adhere to toner materials, reducing their content can improve durability. On the other hand, highly hydrophobic release agents have poor dispersibility in toner, so they tend to form larger domains in the raw material mixture during toner manufacturing, and are prone to cracking at the domain interface during pulverization, and tend to be concentrated on the small particle size component side of the toner mother particles. Reducing the content of small particle size components lowers the release agent content in the toner mother particles, which may weaken the release effect and worsen the resistance to hot offset. Therefore, in this invention, an amorphous polyester resin A, which is a polycondensate of an alcohol component, a carboxylic acid component, and PET, is used while reducing the small particle size component of the toner particles. In the amorphous polyester resin A obtained using PET, the PET is incorporated into the polyester resin chain by a transesterification reaction while undergoing depolymerization during the polycondensation reaction of the alcohol component, carboxylic acid component, and PET, but it does not become completely randomized and exists in the resin as units of a certain length that can be called PET segments. Due to the presence of these PET segments, the uniformity of amorphous polyester resin A is moderately reduced, and the resin becomes more prone to cracking near the PET segments, so the uneven distribution of the release agent towards the small particle size component side of the toner mother particles can be reduced, and as a result, it is presumed that a toner with excellent hot offset resistance and durability can be obtained.

[0011] The crystalline or amorphous nature of a resin is determined by its crystallinity index. The crystallinity index is defined as the ratio of the resin's softening point to its maximum endothermic peak temperature (softening point (°C) / maximum endothermic peak temperature (°C)) in the measurement method described in the examples below. A crystalline resin is one in which the crystallinity index is between 0.6 and 1.4. An amorphous resin is one in which no endothermic peak is observed, or if observed, the crystallinity index is less than 0.6 or greater than 1.4. The crystallinity of the resin can be adjusted by the type and ratio of raw material monomers, and manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum peak temperature of endotherm refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum peak temperature of endotherm is taken as the melting point.

[0012] The number median particle diameter (D 50 ) of the toner mother particles is 3.0 μm or more, preferably 3.5 μm or more, more preferably 4.5 μm or more, and 10.0 μm or less, preferably 9.0 μm or less, more preferably 8.0 μm or less, from the viewpoints of low-temperature fixing property and durability under high temperature and high humidity. In this specification, the number median particle diameter (D 50 ) means the particle diameter at which the cumulative number frequency calculated by the number fraction becomes 50% when calculated from the smaller particle diameter.

[0013] Also, in the number particle size distribution of the toner mother particles, the proportion of particles from 0 μm to (D 50 -2.0) μm is 9.5 number % or less, preferably 7.0 number % or less, more preferably 6.0 number % or less, still more preferably 5.5 number % or less.

[0014] The coefficient of variation (CV value) based on the volume particle size distribution of the toner mother particles is preferably 14% or more from the viewpoint of improving toner productivity, and preferably 18% or less, more preferably 17% or less, still more preferably 16% or less from the viewpoint of developability.

[0015] The particle size distribution of the toner mother particles can be appropriately adjusted by grinding conditions and classification conditions.

[0016] The amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and PET.

[0017] The alcohol component is, from the viewpoint of low-temperature fixing property, represented by the formula (I):

[0018] <​

[0019] (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 value of 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 preferably contained in a compound represented by the formula. Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, and the like. It is preferable to use one or more of these.

[0020] The content of the alkylene oxide adduct of bisphenol A 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 unit of PET is not included in the alcohol component referred to here.

[0021] Examples of other alcohol components include aliphatic diols, alcohols having three or more valences, and the like.

[0022] 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.

[0023] Examples of alcohols having three or more valences include glycerin, trimethylolpropane, pentaerythritol, and the like.

[0024] From the viewpoint of hot offset resistance, the carboxylic acid component preferably contains an aromatic dicarboxylic acid-based compound.

[0025] 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.

[0026] The content of aromatic dicarboxylic acid compounds is preferably 20 mol% or more, more preferably 35 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.

[0027] 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.

[0028] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0029] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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 resistance to hot offsetting, 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In the toner of the present invention, amorphous polyester resin A is contained as a binder resin (binder).

[0045] The content of amorphous polyester resin A in the binder resin is preferably 25% by mass or more, more preferably 50% by mass or more, even more preferably 70% 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.

[0046] Other binder resins include amorphous polyester resins, 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, which are polycondensates of alcohols and carboxylic acid components that do not use PET.

[0047] 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.

[0048] 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.

[0049] 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 resistance to hot offset and low-temperature fixing.

[0050] 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.

[0051] The mass ratio of resin AH to resin AL (resin AH / resin AL) is preferably 10 / 90 or more, more preferably 15 / 85 or more, even more preferably 20 / 80 or more, and preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 70 / 30 or less.

[0052] The binder resin content in the toner is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and preferably 99.5% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less.

[0053] 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.

[0054] 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.

[0055] 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, per 100 parts by mass of binder resin, from the viewpoint of low-temperature fixation and offset resistance of the toner and dispersibility in the binder resin.

[0056] The toner of the present invention may contain additives such as colorants, charge control agents, magnetic powders, flowability improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties improvers.

[0057] As colorants, dyes, pigments, magnetic materials, etc., used as colorants for toners can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. In this invention, the toner may be either black toner or color toner.

[0058] From the viewpoint of improving the toner's image density and low-temperature fixability, the colorant content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, 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] 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. Two or more types may be used in combination. Among these, silica is preferred, and from the viewpoint of toner fluidity, hydrophobic silica that has been hydrophobized is more preferred.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The toner of the present invention may be obtained by any of the conventionally known methods, such as the melt-kneading method, the emulsification-coagulation method, or the suspension polymerization method. However, from the viewpoint of achieving more pronounced effects of the present invention, it is preferable that the toner be produced by the melt-kneading method.

[0068] Therefore, the toner of the present invention is preferably manufactured by a method comprising the steps of: melting and kneading a mixture containing amorphous polyester resin A, a mold release agent, and optionally additives such as a colorant and a charge control agent (melt kneading step); crushing and classifying the resulting mixture to obtain toner base particles (crushing and classification step); and mixing the obtained toner base particles with an external additive (external additive step).

[0069] The mixture to be subjected to melt kneading may be kneaded all at once or in portions, but it is preferable to mix it beforehand using a mixer such as a Henschel mixer or ball mill before supplying it to the melt kneading process.

[0070] Melt mixing can be carried out using known mixing machines such as closed-type kneaders, single-screw or twin-screw extruders, and open-roll type mixers.

[0071] After melt-kneading, it is preferable to cool the mixture appropriately until it reaches a hardness that allows for pulverization, and then perform a pulverization and classification process to obtain toner base particles. Here, cooling refers to cooling the mixture to a temperature between 0°C and 50°C, or to a temperature below the glass transition temperature of the binder resin in the mixture.

[0072] In grinding a compound, the compound may be ground to the desired particle size all at once or in stages. However, from the viewpoint of efficient and more uniform grinding, it is preferable to perform the grinding in two stages: coarse grinding and fine grinding.

[0073] Examples of grinders used for coarse grinding include hammer mills, cutter mills, atomizers, and Rotoplexes.

[0074] For coarse grinding, it is preferable to grind the material until the maximum diameter is 3 mm or less, more preferably 2 mm or less. For example, a pulverized material with a maximum diameter of 3 mm or less can be obtained by coarsely grinding the kneaded material to a particle size of approximately 0.05 mm to 3 mm, then passing it through a sieve with a mesh size of 3 mm, and obtaining the pulverized material that passes through the sieve.

[0075] Examples of grinders used for fine grinding include fluidized bed jet mills, impact plate jet mills, and other types of jet mills, as well as mechanical mills.

[0076] The degree of fine grinding is preferably adjusted as appropriate according to the desired particle size of the toner base particles.

[0077] Classifiers used for classification include air-flow classifiers, inertia classifiers, and sieve classifiers. During the classification process, any pulverized material that is removed due to insufficient pulverization may be subjected to the pulverization process again, and the pulverization and classification processes may be repeated as needed.

[0078] The external additive step, in which the toner base particles and external additives are mixed, can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

[0079] 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]

[0080] 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.

[0081] [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 viscosity 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).]

[0082] [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.

[0083] [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.

[0084] [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 0°C at a rate of 10°C / min. Next, the sample is heated again 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.

[0085] [Acid value of resins] The measurement will be performed according to the method of JIS K 0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixture specified in JIS K 0070 to an acetone and toluene mixture (acetone:toluene = 1:1 (volume ratio)).

[0086] [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.

[0087] [Particle size distribution of toner matrix particles, number of median particle size (D 50 ) and coefficient of variation (CV value)] • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm · Analysis software: "Multi-Sizer (registered trademark) III Version 3.51" (manufactured by Beckman Coulter, Inc.) · Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) · Dispersion liquid: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust to 5% by mass · Dispersion conditions: Add 10 mg of the measurement sample to 5 mL of the above dispersion liquid, disperse for 1 minute with an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W), then add 25 mL of the electrolyte, and further disperse for 1 minute with the ultrasonic disperser to prepare a sample dispersion liquid. · Measurement conditions: By adding the above sample dispersion liquid to 100 mL of the electrolyte, adjust to a concentration at which the particle sizes of 30,000 particles can be measured in 20 seconds, then measure 30,000 particles, and from the particle size distribution, obtain the number median particle size (D 50 ) and the volume average particle size (D V ). Also, the coefficient of variation (CV) value (%) is calculated according to the following formula. CV value (%) = (standard deviation of particle size distribution / volume average particle size (D V )) × 100

[0088] 〔Average particle size of external additive〕 The average particle size refers to the number average particle size. Measure the particle sizes (average value of major axis and minor axis) of 500 particles (primary particles) from a scanning electron microscope (SEM) photograph, and take their number average value.

[0089] Resin production 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 nitrogen inlet tube, stirrer, and 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.

[0090] 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 nitrogen inlet tube, stirrer, and 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 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.

[0091] 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 nitrogen inlet tube, stirrer, and 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.

[0092] 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 nitrogen inlet tube, stirrer, and 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 continued 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.

[0093] 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 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.

[0094] 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 nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out 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.

[0095] 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 nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out at 235°C for 6 hours. Then, the temperature was lowered to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 4 were added. The reaction was carried out at 180°C for 1 hour, and then the temperature was raised from 180°C to 210°C at a rate of 10°C / h, and polycondensation was carried out at 210°C for another 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.

[0096] 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 nitrogen inlet tube, stirrer, and thermocouple. Under a nitrogen atmosphere, the temperature was raised to 235°C, and polycondensation was carried out 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.

[0097] 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.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] Examples 1-17, 21, Comparative Examples 1-3 100 parts by mass of the binder resin shown in Table 5, 5 parts by mass of the coloring agent "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue (PB15:3)), 3 parts by mass of the release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83℃), and 0.5 parts by mass of the charge control agent "Bontron E-304" (manufactured by Orient Chemical Industry 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 mixture was cooled to approximately 25°C, then coarsely ground using a Rotoplex pulverizer (manufactured by Hosokawa Micron Corporation), and passed through a sieve with a mesh size of 2 mm to obtain coarsely ground material with a maximum diameter of 2 mm or less. This coarsely ground material was then finely ground using an IDS-2 type impact plate jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and finally processed using a DS-2 type airflow classifier (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain the medium particle size (D) as shown in Table 5. 50 ) and from 0 μm to (D 50 Toner particles were obtained by adjusting the static pressure (internal pressure) to achieve a particle ratio of up to -2.0 μm and then performing classification.

[0105] Toner was obtained by mixing 100 parts by mass of the obtained toner particles with 1 part by mass of "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: DMDS, average particle size: 16 nm) and 2 parts by mass of "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic silica, hydrophobic treatment agent: silicone oil, 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] Example 18 A toner was obtained in the same manner as in Example 1, except that the amount of "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83°C) used as a release agent was changed to 2 parts by mass, and 1 part by mass of "FNP-0090" (Fischer-Tropsch Wax, manufactured by Nippon Seiro Co., Ltd., melting point: 90°C) was also used.

[0107] Example 19 A toner was obtained in the same manner as in Example 1, except that 3 parts by mass of "FNP-0090" (Fischer-Tropsch wax, manufactured by Nippon Seiro Co., Ltd., melting point: 90°C) was used as a release agent instead of "Carnauba wax C1".

[0108] Example 20 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.

[0109] Test Example 1 [Toner's Hot Offset Resistance] A modified fuser unit of the "AR-505" copier (manufactured by Sharp Corporation) was modified to allow for external fixing. Toner was then installed in this modified unit, and a printout was obtained in an unfixed state (print area: 2cm x 12cm, toner adhesion amount: 0.5mg / cm²). 2 Subsequently, using a fuser (fixing speed 300 mm / sec) adjusted to achieve a total fixing pressure of 40 kgf, fixing tests were conducted on unfixed printed materials at each temperature, while sequentially increasing the temperature of the fuser roll from 120°C to 200°C in 5°C increments. The fixing paper used was "CopyBond SF-70NA" (manufactured by Sharp Corporation, 75 g / m²). 2 ) was used. The resulting printed images were visually observed, and the temperature at which hot offset occurred was identified as the hot offset resistance. The results are shown in Table 5. A higher temperature at which hot offset occurs indicates better hot offset resistance. In the table, ">200" indicates that no hot offset occurred even at 200°C.

[0110] Test Example 2 [Toner Durability] A toner was installed in a "PagePresto N-4" printing press (manufactured by Casio Computer Co., Ltd., fixing method: contact fixing method, developing method: non-magnetic one-component developing method, developing roll diameter: 2.3 cm), and a diagonal stripe pattern with a blackening rate of 5.5% was continuously printed in an environment of 32°C and 85% relative humidity. Every 500 sheets, a solid black image was printed to check for the presence of streaks on the image. Printing was stopped when streaks appeared on the image, and continued up to a maximum of 9000 sheets. Durability was evaluated by counting the number of printed pages up to the point where streaks were visually observed on the image, which was defined as the number of pages where streaks occurred due to toner fusion and fixation on the developing roll. The results are shown in Table 5. In the table, ">9000" means that no streaks occurred even after 9000 prints. A higher number of pages without streaks indicates superior toner durability.

[0111] [Table 5]

[0112] From the above results, it can be seen that the toners of Examples 1 to 21 have good hot offset resistance and durability. In contrast, the toners of Comparative Examples 1 and 2, which use polyester resin without PET or polyester resin using ethylene glycol and terephthalic acid instead of PET, have insufficient hot offset resistance, and the toner of Comparative Example 3, which has a large amount of small particle size components, has insufficient durability. [Industrial applicability]

[0113] The electrostatic image developing 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 toner for electrostatic image development containing amorphous polyester resin A and a mold release agent, and an external additive, wherein the amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the median particle size (D) is determined based on the particle size distribution of the toner mother particles. ５０ ) is 3.0 μm or more and 10.0 μm or less, and from 0 μm to (D ５０ A toner for developing electrostatic images in which the proportion of particles up to -2.0 μm is 9.5% or less.

2. The electrostatic image developing 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 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 electrostatic image developing toner according to claim 1 or 2, wherein the coefficient of variation (CV value) based on the volume particle size distribution of the toner matrix particles is 14% or more and 18% or less.

5. A method for producing electrostatic image developing toner according to claim 1 or 2, comprising the steps of: melt-kneading a mixture containing amorphous polyester resin A and a mold release agent; crushing and classifying the resulting mixture to obtain toner matrix particles; and mixing the obtained toner matrix particles with an external additive.

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