Method for manufacturing a binder resin composition for toner.

Abstract

This relates to a method for producing a binder resin composition for toner that yields highly transparent images. [Solution] A method for producing a binder resin composition for toner containing amorphous polyester resin A and an antioxidant, wherein the alcohol component of the amorphous polyester resin A contains 20 mol% or more of an alkylene oxide adduct of bisphenol A, the oxidation-reduction potential of the antioxidant is -0.5V or more and 0.5V or less, and the method includes the step of adding the antioxidant when the reaction rate of the raw material monomer of the amorphous polyester resin A is 70% or less, and polycondensing the raw material monomer of the amorphous polyester resin A.

Description

Technical Field

[0001] The present invention relates to a method for producing a binder resin composition for toner used for developing a latent image formed in, for example, an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Background Art

[0002] Polyester resins are used as binder resins for electrophotographic toners by utilizing their chemical and physical properties.

[0003] Patent Document 1 addresses the problem of providing a toner binder used for a toner having excellent durability and chargeability and a wide fixing width, and includes a polyester resin in which an alcohol component contains ethylene glycol and a carboxylic acid component contains terephthalic acid and isophthalic acid, and the polyester resin contains a predetermined amount of calcium. An invention related to the toner binder is disclosed.

[0004] Patent Document 2 addresses the problem of providing a method for producing a polyester resin having excellent emulsion stability, compatibility with a crystalline polyester resin, and coloring properties, and is a method for producing a polyester resin by polycondensing an alcohol component (x) containing an alkylene oxide adduct (x1) of bisphenol A and a carboxylic acid component (y) containing an aromatic dicarboxylic acid (y1). The method includes a first polycondensation step of polycondensing until the acid value of the reactant becomes 2 mgKOH / g or less in the presence of a titanium compound and an amine compound having an acid dissociation constant (pKa) of 7 to 10, and a second polycondensation step of adding isophthalic acid to the reactant obtained in the first polycondensation step and further polycondensing. An invention related to the method for producing a polyester resin is disclosed.

[0005] Patent Document 3 addresses the problem of providing a polyester resin having good heat stability, and is a polyester resin synthesized by containing at least a phenolic antioxidant and containing a trivalent or higher polyvalent carboxylic acid or its anhydride, and / or a trivalent or higher polyhydric alcohol. An invention related to a polyester resin in which the ratio of an ultra-high molecular weight body to a high molecular weight body is controlled is disclosed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-10575 [Patent Document 2] Japanese Patent Publication No. 2022-111067 [Patent Document 3] Japanese Patent Application Publication No. 11-246747 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, printing on media such as film and labels, in addition to paper, has increased. Therefore, there is a need for toner binder resins that can produce highly transparent images and widely represent images with high light transmittance on these media.

[0008] This invention relates to a method for producing a binder resin composition for toner that yields highly transparent images. [Means for solving the problem]

[0009] The present invention relates to a method for producing a binder resin composition for toner containing an amorphous polyester resin A and an antioxidant, wherein the alcohol component of the amorphous polyester resin A contains 20 mol% or more of an alkylene oxide adduct of bisphenol A, the oxidation-reduction potential of the antioxidant is -0.5V or more and 0.5V or less, and the method includes the step of adding the antioxidant when the reaction rate of the raw material monomers of the amorphous polyester resin A is 70% or less, and polycondensing the raw material monomers of the amorphous polyester resin A. [Effects of the Invention]

[0010] The present invention provides a binder resin composition for toners that yields highly transparent images. [Modes for carrying out the invention]

[0011] The present invention provides a method for obtaining a toner binder resin composition (hereinafter also referred to as "resin composition") containing an amorphous polyester resin in which the alcohol component contains a predetermined amount of an alkylene oxide adduct of bisphenol A, and an antioxidant having a specific oxidation-reduction potential, by a method that includes the step of polycondensation of raw material monomers of the amorphous polyester resin in the presence of the antioxidant. The details of why the transparency of the image is improved are not clear, but it is presumed to be as follows.

[0012] When polyester resins are subjected to excessive heat during manufacturing, oxidative decomposition reactions occur, generating highly crystalline by-products derived from low-boiling point diols. These by-products are thought to cause clouding of printed materials, reducing image transparency. Furthermore, if by-products derived from alkylene oxide adducts of bisphenol A are generated by the oxidative decomposition reaction, their poor compatibility with the by-products derived from low-boiling point diols promotes the crystallization of the low-boiling point diol by-products, leading to further clouding of printed materials and a further decrease in image transparency. Therefore, after investigating means to control the generation of by-products, it was found that although the oxidative decomposition reaction proceeds exponentially with respect to the reaction time, by adding an alcohol component containing the alkylene oxide adduct of bisphenol A and an antioxidant at the start of the reaction or during the reaction, the antioxidant can be positioned near the alcohol component containing the alkylene oxide adduct of bisphenol A during polycondensation, thereby suppressing the initial oxidative decomposition reaction and effectively reducing the amount of by-products. Furthermore, antioxidants with a low oxidation-reduction potential are strongly oxidized themselves, thereby strongly suppressing oxidative decomposition reactions during resin manufacturing and dramatically reducing the amount of by-products. Furthermore, by using a specific amount or more of a bisphenol A alkylene oxide adduct as the alcohol component of the amorphous polyester resin, the bisphenol A alkylene oxide adduct is incorporated into the resin, and the crystallinity derived from the low-boiling point diol is disrupted, making it possible to create a state in which highly crystalline by-products are less likely to be formed. Therefore, it is believed that reducing the amount of by-products and further suppressing their crystallization will improve image transparency.

[0013] 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 a resin can be adjusted by the type and ratio of raw material monomers, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate). The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0014] The alcohol component of amorphous polyester resin A contains 20 mol% or more of an alkylene oxide adduct of bisphenol A. Therefore, amorphous polyester resin A is preferably a polycondensate of an alcohol component containing 20 mol% or more of an alkylene oxide adduct of bisphenol A and a carboxylic acid component.

[0015] The alkylene oxide adduct of bisphenol A is given by formula (I):

[0016] [ka]

[0017] (In the formula, OR and RO are oxyalkylene groups, R is an ethylene group and / or a propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number, and the sum of x and y is 1 or greater, preferably 1.5 or greater, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.) The compound represented by is preferred.

[0018] From the viewpoint of low-temperature fixing property, the content of the alkylene oxide adduct of bisphenol A is 20 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol% or more, and 100 mol% or less in the alcohol component.

[0019] Examples of other alcohol components include aliphatic diols, diols such as bisphenol A and hydrogenated bisphenol A, and polyhydric alcohols having three or more valences such as sorbitol, pentaerythritol, glycerin, and trimethylolpropane. Among these, aliphatic diols are preferred from the viewpoint of the reactivity of the esterification reaction.

[0020] Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 1,4-butenediol, 1,3-butadiene diol, 1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and the like.

[0021] The number of carbon atoms of the aliphatic diol is 2 or more, and preferably 5 or less, more preferably 4 or less, still more preferably 3 or less.

[0022] The content of the aliphatic diol is 0 mol% or more and 80 mol% or less, preferably 70 mol% or less, more preferably 60 mol% or less, still more preferably 50 mol% or less in the alcohol component.

[0023] From the viewpoint of low-temperature fixability, the carboxylic acid component preferably contains an aromatic dicarboxylic acid compound.

[0024] 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.

[0025] The content of aromatic dicarboxylic acid compounds is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 50 mol% or more, and 100 mol% or less, of the carboxylic acid component.

[0026] Furthermore, the carboxylic acid component may contain trivalent or higher carboxylic acid compounds from the viewpoint of productivity and storage under high humidity.

[0027] Examples of carboxylic acid compounds with a valency of 3 or higher include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0028] The content of trivalent or higher carboxylic acid compounds is 0 mol% or more of the carboxylic acid component, preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less.

[0029] 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, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0030] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monohydric carboxylic acid compound, as appropriate.

[0031] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0032] The equivalent ratio (COOH group / OH group) of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component 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, from the viewpoint of adjusting the softening point of the polyester resin.

[0033] Amorphous polyester resin A is obtained by polycondensing raw material monomers using an antioxidant described later. For example, it can be produced by polycondensing an alcohol component and a carboxylic acid component, which are raw material monomers, in an inert gas atmosphere, in the presence of an antioxidant, preferably in the presence of an esterification catalyst, and optionally in the presence of a co-catalyst, polymerization inhibitor, etc., at a temperature preferably 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0034] Examples of esterification catalysts include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamine) and titanium dihydroxybis(triethanolamine). The amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. 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 and carboxylic acid components. 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 and carboxylic acid components.

[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.

[0036] The content of amorphous polyester resin A in the toner binder resin composition is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, even more preferably 99.5% by mass or more, and preferably 99.995% by mass or less, more preferably 99.99% by mass or less, even more preferably 99.8% by mass or less, and even more preferably 99.7% by mass or less.

[0037] The antioxidant is not particularly limited as long as its oxidation-reduction potential is within a predetermined range, but examples include phosphorus-based antioxidants, sulfur-based antioxidants, triazine-based antioxidants, benzotriazole-based antioxidants, phenol-based antioxidants, and amine-based antioxidants. Among these, phosphorus-based antioxidants having a phosphate group are preferred from the viewpoint of transparency.

[0038] Phosphorus-based antioxidants are not limited to the following, but include, for example, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphorous acid, tetrakis(2,4-di-tert-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonate, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, tetraki Examples include (2,4-tert-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphonate, di-tert-butyl-m-cresyl-phosphonate, 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, tris[2-[[2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphefin-6-yl]oxy]ethyl]amine, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Among these, it is preferable that the phosphorus antioxidant has a phenyl group in addition to a phosphate group, and more preferably a phosphorus-based antioxidant having two or more, preferably two or three or fewer, di-tert-butylphenyl structures. For example, phosphorus-based antioxidants having a phosphate group and a phenyl group include 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol and tris(2,4-di-tert-butylphenyl) phosphite, and is preferably 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepin)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol.

[0039] Commercial phosphorus antioxidants may be used as phosphorus-based antioxidants, and such commercial phosphorus-based antioxidants are not limited to the following, but include, for example, Irgafos 168 (tris(2,4-di-tert-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (tris[2-[[2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphephine-6-yl]oxy]ethyl]amine, manufactured by BASF), Irgafos 38 (bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl) ethyl ester phosphorous acid, manufactured by BASF), and Sumilizer GP. Examples include GP:4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosfepine)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol (manufactured by Sumitomo Chemical Co., Ltd.) and HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd.)).

[0040] From the viewpoint of developability, the oxidation-reduction potential of the antioxidant is -0.5V or higher, preferably -0.1V or higher, more preferably -0.05V or higher, and from the viewpoint of transparency, it is 0.5V or lower, preferably 0.1V or lower, more preferably 0V or lower.

[0041] The amount of antioxidant used is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of raw material monomer of amorphous polyester resin A.

[0042] The toner binder resin composition of the present invention, which contains the amorphous polyester resin A and an antioxidant, is obtained by a method that includes adding the antioxidant at the start of the polycondensation reaction of amorphous polyester resin A or during the reaction, and polycondensing the raw material monomers of amorphous polyester resin A. The polycondensation of the raw material monomers of amorphous polyester resin A is as described above, and the timing of adding the antioxidant is when the reaction rate of the raw material monomers of amorphous polyester resin A is 70% or less, preferably 50% or less, more preferably 30% or less, even more preferably 20% or less, and even more preferably 0%. The point at which the reaction rate is 0% means before the reaction of the raw material monomers or at the start of the reaction, but it is preferable to add the antioxidant together with the raw material monomers at the start of the reaction. Here, the reaction rate of the raw material monomers is calculated from the following formula.

[0043]

number

[0044] The softening point of the toner binder resin composition is preferably 70°C or higher, more preferably 90°C or higher, from the viewpoint of electrostatic stability, and preferably 150°C or lower, more preferably 135°C or lower, and even more preferably 125°C or lower, from the viewpoint of low-temperature fixation.

[0045] The glass transition temperature of the toner binder resin composition is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of storage properties, and preferably 80°C or lower, more preferably 75°C or lower, from the viewpoint of low-temperature fixing properties.

[0046] The acid value of the toner binder resin composition is preferably 1 mg KOH / g or more, more preferably 2 mg KOH / g or more, from the viewpoint of developability, and preferably 40 mg KOH / g or less, more preferably 35 mg KOH / g or less, and even more preferably 20 mg KOH / g or less, from the viewpoint of storage under high humidity.

[0047] The toner binder resin composition obtained by the method of the present invention can be used as is as a binder resin for electrostatic image developing toner, or mixed with other binder resins.

[0048] The content of the toner binder resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and preferably 100% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, in the binder resin.

[0049] Other binder resins include amorphous polyester resins without antioxidants, 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. However, in the present invention, from the viewpoint of high-temperature separation properties, amorphous polyester resin B, which has a higher softening point than amorphous polyester resin A, is preferred.

[0050] Amorphous polyester resin B is obtained in the same manner as amorphous polyester resin A, except that no antioxidant is used during the polycondensation of the raw material monomers.

[0051] The difference in softening points between amorphous polyester resin A and amorphous polyester resin B is preferably 5°C or more, more preferably 10°C or more, even more preferably 15°C or more, and preferably 70°C or less, more preferably 50°C or less, and even more preferably 45°C or less.

[0052] The softening point of amorphous polyester resin B is preferably 120°C or higher, more preferably 130°C or higher, even more preferably 140°C or higher, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower.

[0053] The glass transition temperature of amorphous polyester resin B is preferably 50°C or higher, more preferably 55°C or higher, even more preferably 60°C or higher, and preferably 85°C or lower, more preferably 80°C or lower, and even more preferably 75°C or lower.

[0054] The acid value of amorphous polyester resin B is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, even more preferably 15 mg KOH / g or more, and preferably 40 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 20 mg KOH / g or less.

[0055] The content of amorphous polyester resin B in the binder resin is preferably 0% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0056] The binder resin content in the toner is preferably 50% 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, and preferably less than 100% by mass, more preferably 99% by mass or less, even more preferably 98% by mass or less, and even more preferably 95% by mass or less.

[0057] The toner for developing electrostatic images may contain additives other than the binder resin, such as colorants, release agents, charge control agents, magnetic powders, flowability enhancers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties enhancers.

[0058] 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.

[0059] From the viewpoint of improving the image density of the toner and its low-temperature fixability, the amount of colorant 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.).

[0065] Furthermore, as negative charge control agents, metal-containing azo dyes, such as "Barifast Black 3804," "Bontron S-31," "Bontron S-32," "Bontron S-34," and "Bontron S-36" (all manufactured by Orient Chemical Industries, Ltd.), "Eisenspiron Black TRH," and "T-77" (manufactured by Hodogaya Chemical Co., Ltd.); metal compounds of benzyl 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; and quaternary ammonium salts, such as "COPY CHARGE NX" Examples include VP434 (manufactured by Clariant), nitroimidazole derivatives, organometallic compounds, etc.

[0066] 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.

[0067] The toner may be obtained by any known method such as the melt-kneading method, the emulsification-coagulation method, or the polymerization method, but from the viewpoint of productivity and the dispersibility of the colorant, pulverized toner obtained by the melt-kneading method is preferred. In the case of pulverized toner obtained by the melt-kneading method, for example, raw materials such as binder resin, colorant, release agent, and charge control agent can be uniformly mixed in a mixer such as a Henschel mixer, then melt-kneaded, cooled, pulverized, and classified to produce the toner.

[0068] The mixture to be subjected to melting and kneading may be kneaded all at once or in portions, but it is preferable to mix it beforehand in a mixer such as a Henschel mixer or ball mill before supplying it to the kneader.

[0069] For melt mixing, known mixing machines such as closed-type kneaders, single-screw or twin-screw extruders, and open-roll type mixers can be used.

[0070] The melt-mixing temperature is not particularly limited as long as it is the temperature at which the resin melts and the raw materials mix together.

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

[0072] Toner preferably contains external additives to improve transferability. 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 transferability, hydrophobic silica that has been hydrophobicized is more preferred.

[0073] 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.

[0074] The average particle size of the external additive is preferably 10 nm or larger, more preferably 15 nm or larger, and 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.

[0075] 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.

[0076] 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 3 parts by mass or less, per 100 parts by mass of toner particles before treatment with the external additive.

[0077] Volume-intermediate particle size (D) of toner for electrostatic image developing 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.

[0078] The electrostatic image developing toner can be used as a one-component developing toner on its own, or as a two-component developing toner mixed with a carrier, in image forming apparatuses using either a one-component or two-component developing method, respectively. [Examples]

[0079] 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.

[0080] [Softening point of resins and resin compositions] Using a flow tester "CFT-500EX" (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.

[0081] [Maximum peak temperature of endothermic reactions in resins and resin compositions] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 4.0-5.0 mg of the sample was weighed into an aluminum pan and cooled from room temperature (20°C) to 0°C at a rate of 10°C / min. The sample was then maintained at this temperature for 5 minutes. Subsequently, the endothermic peaks were measured while the temperature was increased to 180°C at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature.

[0082] [Glass transition temperature of resins and resin compositions] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 4.0 to 5.0 mg of the sample is weighed into an aluminum pan and heated from room temperature (20°C) to 200°C at a heating rate of 10°C / min, and then cooled to 0°C at a cooling rate of 10°C / min. Next, the sample is heated to 180°C at a heating 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.

[0083] [Acid value of resins and resin compositions] The measurement will be performed according to the method of JIS K0070:1992. However, the measurement solvent will be changed from the mixed solvent of ethanol and ether specified in JIS K0070:1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[0084] [Oxidation-reduction potential of antioxidants] Cyclic voltammetry measurements will be performed using a WaveNano potentiostat (Pine Research Instrumentation). The following materials will be used as the reference electrode, counter electrode, and working electrode. • Reference electrode: Silver / silver nitrate (As the electrolyte, use a 0.1 mol / L tetraalkylammonium tetrafluoroborate anhydrous acetonitrile solution (Solution A). Also, prepare a fresh 5 mmol / L silver nitrate anhydrous acetonitrile solution (Solution B). Place Solution B in a narrow glass tube with a glass filter at the bottom, and seal it with a rubber stopper into which a 0.5 mm diameter silver wire is inserted. Insert this into a 15 mm diameter glass tube with a glass filter at the bottom containing Solution A, and use this as the reference electrode.) • Counter electrode: Platinum wire • Working electrode: Platinum disc (1.6 mm in diameter) The oxidation potential of antioxidants is measured using a tetrahydrofuran (THF) solution (5 mmol / L) of the antioxidant. A 1 mol / L solution of tetrabutylammonium perchlorate (TBAP) is used as the supporting electrolyte. The reduction scan is performed using a 0.1 mol / L solution of TBAP in acetonitrile for each antioxidant's THF solution (5 mmol / L). Typically, three cycles (six divisions) are performed at a sweep rate of 20 mV / sec. Energy levels are corrected by a 4.7 V offset to convert them to vacuum levels. Using the method described above, a voltammogram is measured for a tetrahydrofuran (THF) solution (5 mmol / L) containing an antioxidant, and the resulting half-wave potential is defined as the redox potential.

[0085] [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 at a rate of 10°C / min and the heat quantity is measured, with the maximum endothermic peak temperature being defined as the melting point.

[0086] [Average particle size of external additives] The average particle diameter refers to the number-average particle diameter, which is calculated by measuring the particle size (average of the major and minor axes) of 500 particles from scanning electron microscope (SEM) images and using the number-average value of these measurements.

[0087] [Medium particle size in toner volume] • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 100 μm • Analysis software: "Multisizer III (registered trademark) Version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: Add 10 mg of the sample to 5 mL of the dispersion and disperse for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80W). Then, add 25 mL of electrolyte and disperse for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, the 30,000 particles are measured, and the volume median particle size (D) is determined from the particle size distribution. 50 )

[0088] Examples 1-5, 8, 10-13, Comparative Examples 2-4 A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dehydration tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid components other than trimellitic anhydride, antioxidant, esterification catalyst, and co-catalyst shown in Tables 2-4. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and held for 4 hours. The pressure inside the flask was then reduced and held at 8 kPa for 1 hour. After cooling to 210°C and returning to atmospheric pressure, trimellitic anhydride shown in Tables 2-4 was added. The mixture was held at 210°C for 3 hours, and then the pressure inside the flask was further reduced to 16.7 kPa. The mixture was reacted until the softening point reached the temperature shown in Tables 2-4, yielding a resin composition containing amorphous polyester resin and antioxidant. The physical properties of the obtained resin composition are shown in Tables 2-4.

[0089] Examples 6, 7, 14 A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid component, antioxidant, esterification catalyst, and co-catalyst shown in Tables 2-4. Under a nitrogen atmosphere, the mixture was heated to 235°C while stirring and held for 4 hours. Then, the pressure inside the flask was reduced to 16.7 kPa and the mixture was reacted until the softening point reached the temperature shown in Tables 2-4 to obtain a resin composition containing amorphous polyester resin and antioxidant. The physical properties of the obtained resin composition are shown in Tables 2-4.

[0090] Example 9 A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid component, esterification catalyst, co-catalyst, and antioxidant shown in Table 3. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and held for 2 hours. After that, it was cooled to 210°C and returned to atmospheric pressure. Then, the fumaric acid and polymerization inhibitor shown in Table 3 were added, and the mixture was held at 210°C for 3 hours. Subsequently, the pressure in the flask was reduced, and the reaction was carried out at 16.7 kPa until the softening point reached the temperature shown in Table 3, yielding a resin composition containing amorphous polyester resin and antioxidant. The physical properties of the obtained resin composition are shown in Table 3.

[0091] Examples 15-18 A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 5. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and maintained until reaction water corresponding to the reaction rate shown in Table 5 was produced. Subsequently, the antioxidant was added and the mixture was stirred until reaction water corresponding to a reaction rate of 75% was produced. The pressure in the flask was then reduced and maintained at 8 kPa for 1 hour. After that, the mixture was cooled to 210°C and returned to atmospheric pressure. Then, trimellitic anhydride shown in Table 5 was added and maintained at 210°C for 3 hours. The pressure in the flask was further reduced to 16.7 kPa and the mixture was reacted until the softening point reached the temperature shown in Table 5, thereby obtaining a resin composition containing amorphous polyester resin and antioxidant. The physical properties of the obtained resin composition are shown in Table 5.

[0092] Comparative Example 1 A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 4. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and held for 4 hours. The pressure inside the flask was then reduced and held at 8 kPa until reaction water corresponding to the reaction rate shown in Table 4 was produced. After that, the mixture was cooled to 210°C and returned to atmospheric pressure. The trimellitic anhydride and antioxidant shown in Table 4 were added, and the mixture was held at 210°C for 3 hours. The pressure inside the flask was then reduced further and the mixture was reacted at 16.7 kPa until the softening point reached the temperature shown in Table 4, thereby obtaining a resin composition containing amorphous polyester resin and antioxidant. The physical properties of the obtained resin composition are shown in Table 4.

[0093] Details of the antioxidants used in the examples and comparative examples are shown in Table 1.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] [Table 5]

[0099] Examples of resin manufacturing A 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dehydration tube, and a nitrogen inlet tube contained the alcohol component, carboxylic acid components other than trimellitic anhydride, esterification catalyst, and co-catalyst shown in Table 6. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and held for 4 hours. The pressure inside the flask was then reduced and held at 8 kPa for 1 hour. After that, the mixture was cooled to 210°C and returned to atmospheric pressure. Trimellitic anhydride as shown in Table 6 was added, and the mixture was held at 210°C for 3 hours. The pressure inside the flask was then reduced further and the mixture was reacted at 16.7 kPa until the softening point reached the temperature shown in Table 6, thereby obtaining amorphous polyester resin (resin B). The physical properties of the obtained resin are shown in Table 6.

[0100] [Table 6]

[0101] Toner manufacturing examples 1-22 100 parts by mass of the binder resin (resin composition of the example or comparative example and resin B) shown in Table 7, 1 part by mass of the negative charge control agent "Bontron E-81" (manufactured by Orient Chemical Industry Co., Ltd.), 5 parts by mass of the coloring agent "Pigment blue 15:3" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue), and 2 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80℃) were thoroughly mixed in a Henschel mixer. Then, using a twin-screw extruder with a total length of 1560 mm in the mixing section, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, the mixture was melt-kneaded at a roll rotation speed of 200 r / min and a heating temperature in the rolls of 100℃. The feed rate of the mixture was 20 kg / h, and the average residence time was approximately 18 seconds. The resulting kneaded material was cooled and coarsely ground, then ground in a jet mill and classified to obtain the medium volume particle size (D 50 ) yielded toner particles with a diameter of 8 μm.

[0102] To 100 parts by mass of the obtained toner particles, 1 part by mass of hydrophobic silica "AEROSIL NAX 50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: HMDS, average particle size: approximately 30 nm) was added as an external additive, and the mixture was combined in a Henschel mixer to obtain toner (toners 1 to 22).

[0103] Test example [Transparency] A solid image was printed on an A4-sized OHP sheet (manufactured by Nakabayashi Co., Ltd., OHP film, double-sided dry copy for LBP). The resulting solid image was cut into 4cm x 5cm sections, and the light transmittance was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., SE2000) to evaluate the transparency of the image. Transmittance was measured by first cutting an unprinted OHP sheet to 4cm x 5cm and fixing it to a jig with a measurement area of ​​30mmΦ. Background measurements were then taken of the unprinted OHP sheet, and then the absorbance of an OHP sheet with a solid image printed on it was measured using the same method. During this process, the OHP sheet was positioned so that the light was shone from the back of the printed side of the solid image. Measurements were taken in the range of 380 to 780nm with wavelength output intervals of 10nm. The absorbance at 480nm was evaluated as the transmittance of cyan. Transmittance was evaluated as follows: Transmittance = (Absorbance at 480nm of the printed OHP sheet) / (Absorbance at 480nm of the unprinted OHP sheet) × 100 (%). The results are shown in Table 7. Higher transmittance indicates higher transparency.

[0104] [Table 7]

[0105] From the above results, it can be seen that toners 19-22 using the resin compositions of Comparative Example 1, where the antioxidant was added too late; Comparative Example 2, where the content of the bisphenol A alkylene oxide adduct was outside the specified range; and Comparative Examples 3 and 4, where the oxidation-reduction potential of the antioxidant was outside the specified range even though the timing of antioxidant addition was within the specified range, all toners 1-18 using the resin compositions of Examples 1-18 yielded images with high transparency. [Industrial applicability]

[0106] A toner containing a binder resin composition for toner obtained by the method of the present invention is suitably used for developing latent images formed in electrostatic image development, electrostatic recording, electrostatic printing, and the like.

Claims

1. A method for producing a binder resin composition for toner containing amorphous polyester resin A and an antioxidant, wherein the alcohol component of the amorphous polyester resin A contains 20 mol% or more of an alkylene oxide adduct of bisphenol A, the oxidation-reduction potential of the antioxidant is -0.5 V or more and 0.5 V or less, and the method includes the step of adding the antioxidant when the reaction rate of the raw material monomer of the amorphous polyester resin A is 70% or less, and polycondensing the raw material monomer of the amorphous polyester resin A.

2. A method for producing a binder resin composition for toner according to claim 1, wherein the antioxidant is a phosphorus-based antioxidant.

3. A method for producing a binder resin composition for toner according to claim 1 or 2, wherein the amount of antioxidant used is 0.1 parts by mass or more per 100 parts by mass of the raw material monomer of amorphous polyester resin A.

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