Toner for developing electrostatic images

Abstract

To provide a toner for electrostatic image development that offers excellent resistance to hot offset and durability. [Solution] A toner for developing electrostatic images, comprising toner particles containing a binder resin and a release agent, The amorphous composite resin A comprises a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylate ester resin segment which is an addition polymer of raw material monomers containing a methacrylate ester. A toner for developing electrostatic images, wherein the release agent contains ester wax.

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. [Background technology]

[0002] A toner for electrostatic development is known that contains a vinyl polymer-grafted polyester resin, which is a polyester resin grafted with a vinyl polymer (Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-010786 [Overview of the project]

[0004] Toners for electrostatic image development require so-called hot offset resistance, meaning they adhere only to the printing substrate, such as paper, when heat is applied during printing, and do not easily adhere to the fuser or other components of the printing press. Furthermore, electrostatic image development toners also require durability to reduce contamination of printing press components during continuous printing.

[0005] However, conventional electrostatic image developing toners had room for improvement in terms of achieving both resistance to hot offset and durability.

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

[0007] The present invention A toner for electrostatic image development (hereinafter also simply referred to as "toner") containing toner particles containing a binder resin and a release agent, The amorphous composite resin A comprises a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylate ester resin segment which is an addition polymer of raw material monomers containing a methacrylate ester. The aforementioned release agent contains ester wax. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a toner for electrostatic image development that has excellent resistance to hot offset and durability. [Modes for carrying out the invention]

[0009] <Toner> The toner of this embodiment is A toner containing toner particles containing a binder resin and a release agent, The amorphous composite resin A comprises a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylate ester resin segment which is an addition polymer of raw material monomers containing a methacrylate ester. The aforementioned release agent contains ester wax. The toner of this embodiment exhibits excellent resistance to hot offset and durability. The reason why the toner of this embodiment exhibits these effects is not entirely clear, but it is presumed to be as follows.

[0010] The toner of this embodiment contains an amorphous composite resin A having a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component as a binder resin, and a polymethacrylate resin segment which is an addition polymer of a raw material monomer containing a methacrylate, and contains an ester wax as a release agent. Since the polymethacrylate resin segment contains many ester groups in its molecular skeleton, the ester wax is finely dispersed in the binder resin due to the interaction with the ester wax. The finely dispersed wax domains are likely to become interfaces during the pulverization of toner production, so the ester wax can be present near the toner surface as fine domains. As a result, while suppressing excessive wax surface exposure, the release effect by the ester wax near the surface is significantly exhibited, so it is presumed that excellent hot offset resistance and durability can be achieved simultaneously.

[0011] 〔Toner particles〕 [Binder resin] The toner particles contain the binder resin, and the binder resin contains an amorphous composite resin A including a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylate resin segment which is an addition polymer of a raw material monomer containing a methacrylate, from the viewpoint of achieving both hot offset resistance and durability.

[0012] (Amorphous composite resin A) The amorphous composite resin A includes a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylate resin segment which is an addition polymer of a raw material monomer containing a methacrylate, from the viewpoint of improving durability.

[0013] (Polyester resin segment) As the alcohol component, a compound represented by the formula (I) is preferable from the viewpoint of low-temperature fixing property.

Chemical formula

[0014] Examples of the compound represented by the formula (I) include polyoxypropylene adducts of 2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene adducts of 2,2-bis(4-hydroxyphenyl)propane, etc. It is preferable to use one or more of these.

[0015] The content of the compound represented by the formula (I) in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, even more preferably substantially 100 mol%, and even more preferably 100 mol%. In this specification, "substantially" means that it may contain trace amounts of components included unintentionally.

[0016] The alcohol component may contain an alcohol component other than the compound represented by the formula (I). Examples of the alcohol component other than the compound represented by the formula (I) include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and polyhydric alcohols such as trimethylolpropane with three or more hydroxyl groups. In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component.

[0017] Examples of the carboxylic acid component include aromatic dicarboxylic acid compounds, aliphatic dicarboxylic acid compounds, and polyvalent carboxylic acid compounds with three or more carboxyl groups. In this specification, macromonomers and hydroxycarboxylic acids are not included in the carboxylic acid component.

[0018] Examples of the aforementioned aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0019] The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and 100 mol or less.

[0020] Examples of the aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

[0021] 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.

[0022] 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 amorphous polyester resin A.

[0023] The polyester resin constituting the polyester resin segment can be formed, for example, by polycondensing the alcohol component and the carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and optionally in the presence of an esterification 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.

[0024] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine. 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 raw material monomer. Examples of esterification co-catalysts include gallic acid. The amount of esterification 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 raw material monomer. 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, per 100 parts by mass of the raw material monomer.

[0025] The weight-average molecular weight of the polyester resin constituting the polyester resin segment is preferably 3000 or more from the viewpoint of hot offset resistance, and preferably 5000 or less from the viewpoint of low-temperature fixation. In this specification, the weight-average molecular weight of the resin is measured by the method described in the examples.

[0026] (Polymethacrylate resin segment) The aforementioned raw material monomer contains a methacrylic acid ester, from the viewpoint of achieving both resistance to hot offsetting and durability.

[0027] As the methacrylic acid ester, alkyl methacrylate esters having 1 to 6 carbon atoms in the alkyl group are preferred. Examples of such alkyl methacrylate esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, and the like, with methyl methacrylate being preferred among them.

[0028] The raw material monomer may contain vinyl monomers other than methacrylic acid esters that can copolymerize with methacrylic acid esters, in addition to methacrylic acid esters. Examples of the vinyl monomers include one or more selected from the group consisting of acrylic monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isodecyl acrylate, lauryl acrylate, tridecyl acrylate, cetyl acrylate, stearyl acrylate, cyclohexyl acrylate, and benzyl acrylate; and styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, and p-chlorostyrene.

[0029] The content of constituent units derived from polymethacrylate in the polymethacrylate resin segment is preferably 80 mol% or more, more preferably substantially 100 mol%, and even more preferably 100 mol%, from the viewpoint of achieving both resistance to hot offset and durability.

[0030] The polymethacrylate resin constituting the polymethacrylate resin segment is obtained by addition polymerization of the raw material monomers. The method of addition polymerization is not particularly limited and can be carried out by known methods. An example of the addition polymerization method is a method in which the raw material monomers are polymerized with a known radical polymerization initiator.

[0031] The weight-average molecular weight of the polymethacrylate resin constituting the polymethacrylate resin segment is preferably 50,000 or more from the viewpoint of hot offset resistance, and preferably 100,000 or less from the viewpoint of low-temperature fixation.

[0032] The polymethacrylate resin constituting the polymethacrylate resin segment may be a commercially available product. Examples of commercially available polymethacrylate methyl resins constituting the polymethacrylate resin segment include "Parapet H1000B", "Parapet GF", "Parapet EH", "Parapet HR-L", "Parapet HR-S", and "Parapet G" (all manufactured by Kuraray Co., Ltd.).

[0033] The amorphous composite resin A can be formed, for example, by transesterifying a polyester resin constituting the polyester resin segment and a polymethacrylate resin constituting the polymethacrylate resin segment in an inert gas atmosphere, preferably in the presence of the esterification catalyst, and optionally in the presence of the esterification 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. The method for producing the amorphous composite resin A includes (i) a polymer reaction method between the polyester resin and the polymethacrylate resin, (ii) a method in which raw material monomers of the polyester resin are reacted in the presence of the polymethacrylate resin, and (iii) a method in which a portion of the raw material monomers of the polyester resin are reacted, and then the polymethacrylate resin and the remaining raw material monomers of the polyester resin are added and the reaction is carried out. These methods may also be carried out using reactive monomers that can react with either polyester resin raw material monomers or polymethacrylate ester resin raw material monomers.

[0034] In the method for producing the amorphous composite resin A, the amount of polymethacrylate ester resin used is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the polyester resin or the raw material monomer of the polyester resin, from the viewpoint of achieving both hot offset resistance and durability, and preferably 100 parts by mass or less, more preferably 50 parts by mass or less, from the viewpoint of low-temperature fixability.

[0035] The content of the polymethacrylate ester resin segment in the amorphous composite resin A is preferably 1 part by mass or more, more preferably 5 parts by mass or more, with respect to 100 parts by mass of the polyester resin segment, from the viewpoint of achieving both hot offset resistance and durability, and preferably 100 parts by mass or less, more preferably 50 parts by mass or less, from the viewpoint of low-temperature fixing properties.

[0036] The softening point of the amorphous composite resin A is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher, from the viewpoint of electrostatic stability, and preferably 170°C or lower, more preferably 160°C or lower, and even more preferably 150°C or lower, from the viewpoint of low-temperature fixability.

[0037] The glass transition temperature of the amorphous composite resin A 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 70°C or lower, from the viewpoint of low-temperature fixing properties.

[0038] The acid value of the amorphous composite resin A is preferably 0.4 mg KOH / g or more, more preferably 0.6 mg KOH / g or more, from the viewpoint of low-temperature fixability, and preferably 20 mg KOH / g or less, more preferably 10 mg KOH / g or less, from the viewpoint of electrostatic stability.

[0039] The content of the amorphous composite resin A in the binder resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and 100% by mass or less, from the viewpoint of improving resistance to hot offset.

[0040] The binder resin may contain resins other than the amorphous composite resin A, to the extent that they do not impair the effects of the present invention. Examples of other resins include 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.

[0041] The crystallinity of a resin is expressed by its crystallinity index, which is defined by the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point / maximum endothermic peak temperature]. Amorphous resins are those in which no endothermic peak is observed, or if observed, the crystallinity index is greater than 1.4 or less than 0.6. On the other hand, crystalline resins are those in which the crystallinity index is 0.6 or greater and 1.4 or less. The crystallinity of a resin can be adjusted by the type and ratio of raw material monomers, and 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.

[0042] The content of the binder resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 75% by mass or more, and preferably 99.5% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less.

[0043] [Release agent] The aforementioned release agent contains ester wax, from the viewpoint of achieving both resistance to hot offsetting and durability.

[0044] Examples of the ester wax include synthetic ester waxes and natural ester waxes. From the viewpoint of achieving both hot offset resistance and durability, synthetic ester waxes are preferred, and fatty acid esters are more preferred. Among these, from the viewpoint of dispersibility in amorphous composite resins, esters obtained by reacting a monovalent aliphatic alcohol having 14 to 24 carbon atoms with a fatty acid having 14 to 24 carbon atoms and / or esters obtained by reacting pentaerythritol with a fatty acid having 14 to 24 carbon atoms are preferred. Examples of commercially available synthetic ester waxes include "Nissan Electol WEP-2", "Nissan Electol WEP-3", "Nissan Electol WEP-4", "Nissan Electol WEP-5", "Nissan Electol WEP-6", "Nissan Electol WEP-8", "WE-10", and "WE-14" (all manufactured by NOF Corporation).

[0045] Examples of natural ester waxes include carnauba wax, candelilla wax, rice wax, wood wax, jojoba wax, and their derivatives.

[0046] The release agent may contain release agents other than the ester wax. Examples of release agents other than the ester wax include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, and their oxides; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc., which can be used individually or in combination of two or more.

[0047] The melting point of the mold release agent is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of electrostatic stability, 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.

[0048] The content of the mold release agent 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, based on the viewpoint of the electrostatic stability of the toner and its dispersibility in the binder resin, per 100 parts by mass of the binder resin.

[0049] From the viewpoint of improving resistance to hot offsetting, the content of the ester wax in the release agent is preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably substantially 100% by mass, and even more preferably 100% by mass.

[0050] The content of the ester wax in the toner particles is preferably 0.3% by mass or more, more preferably 0.6% by mass or more, even more preferably 1.0% by mass or more, and even more preferably 1.4% by mass or more, from the viewpoint of improving hot offset resistance, and preferably 10% by mass or less, and more preferably 5% by mass or less, from the viewpoint of improving durability.

[0051] From the viewpoint of improving resistance to hot offset, the content of the ester wax is preferably 0.35 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the amorphous composite resin A, and from the viewpoint of improving durability, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less.

[0052] The toner particles may contain additives such as colorants, charge control agents, magnetic powders, flowability enhancers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties enhancers.

[0053] As the coloring agent, dyes, pigments, magnetic materials, etc., used as coloring agents 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.

[0054] From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the coloring agent 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.

[0055] 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.

[0056] Examples of the positively charged charge control agent include nigrosine dyes, such as "Nigrosine Base EX," "Oil Black BS," "Oil Black SO," "Bontron N-01," "Bontron N-04," "Bontron N-07," "Bontron N-09," "Bontron N-11," and "Bontron N-79" (all manufactured by Orient Chemical Industries, Ltd.); triphenylmethane-based dyes containing a tertiary amine as a side chain; 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), imidazole derivatives such as PLZ-2001 and PLZ-8001 (both manufactured by Shikoku Chemicals), and styrene-acrylic resins such as FCA-701PT and FCA-201-PS (manufactured by Fujikura Chemicals).

[0057] Examples of the negatively charged charge control agents include 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; quaternary ammonium salts, such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives, etc.; and organometallic compounds.

[0058] From the viewpoint of the charge control agent's charge stability, 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. If the charge control agent is a resin (polymer type), the content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the binder resin.

[0059] The volume median particle size (D) of the toner particles 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. In this specification, the volume median particle size (D) is used. 50 ) refers to the particle size at which the cumulative volume frequency, calculated using volume fractions, accounts for 50% of the total volume frequency, starting from the smallest particle size.

[0060] [External additives] The toner preferably has an external additive on the surface of the toner particles in order to improve transferability. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as melamine resin fine particles and polytetrafluoroethylene resin fine particles, and two or more may be used in combination. Among these, silica is preferred, and from the viewpoint of toner transferability, hydrophobic silica that has been hydrophobicized is more preferred.

[0061] Examples of hydrophobic agents for hydrophobicizing the surface of the silica include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0062] The average particle size of the external additive is preferably 10 nm or more, more preferably 15 nm or more, and preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less, from the viewpoint of the toner's chargeability, fluidity, and transferability.

[0063] The external additive treatment, which involves mixing the toner particles with the external additive, can be carried out according to conventional methods and can be performed using a mixer such as a Henschel mixer.

[0064] 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, based on 100 parts by mass of the toner particles before treatment with the external additive, from the viewpoint of the chargeability, fluidity, and transferability of the toner.

[0065] The electrostatic image developing toner can be used as is as a one-component developing toner, or as a two-component developing toner mixed with a carrier, in image forming apparatuses using either a one-component developing method or a two-component developing method, respectively.

[0066] <Toner manufacturing method> The method for manufacturing the toner is not particularly limited, but for example, it includes a step A for obtaining the toner particles, and a step B for mixing the toner particles obtained in step A with the external additive.

[0067] [Process A] The method for obtaining the toner particles in step A is not limited, and the toner particles can be obtained by known methods such as melt kneading, emulsification agglomeration, and suspension polymerization. Among these, the melt kneading method is preferred from the viewpoint of improving offset resistance and durability.

[0068] When the toner particles are obtained by a melt-kneading method, for example, step A includes at least step A1 of melt-kneading the binder resin, and step A2 of crushing and classifying the melt-kneaded product obtained in step A1.

[0069] [Process A1] If the toner contains the additive, step A1 may be a step of melting and kneading the binder resin and the additive.

[0070] The raw materials for melt kneading, including the binder resin, may be kneaded all at once or in portions, but it is preferable to mix them beforehand in a mixer such as a Henschel mixer or ball mill before supplying them to the kneader. This melt kneading can be carried out using known kneaders such as a closed-type kneader, a single-screw or twin-screw extruder, or an open-roll type kneader.

[0071] [Process A2] After step A1, the kneaded material obtained in step A1 can be cooled appropriately until it reaches a hardness that allows for pulverization, then pulverized and, if necessary, classified to obtain toner particles. Here, cooling means cooling the kneaded material to a temperature of 0°C or higher and 50°C or lower, or cooling it to a temperature below the glass transition temperature of the binder resin in the kneaded material.

[0072] The aforementioned mixture may be ground all at once to the desired particle size or ground in stages, but 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, atomizers, and Rotoplexes.

[0074] For coarse grinding, it is preferable to grind until the maximum diameter is 3 mm or less. 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, and then passing it through a sieve with a mesh size of 3 mm.

[0075] Examples of grinders used for fine grinding include fluidized bed jet mills, impact plate jet mills, and rotary mechanical mills. Among these, fluidized bed jet mills and impact plate jet mills are preferred from the viewpoint of grinding efficiency, with impact plate jet mills being more preferred.

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

[0077] Classifiers used for classification include air-flow classifiers, inertial classifiers, and sieve classifiers.

[0078] [Process B] The mixing of the toner particles and the external additive can be carried out according to conventional methods, and can be done using a mixer such as a Henschel mixer. [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. Pressure is expressed in absolute pressure, and "normal pressure" refers to 101.3 kPa.

[0080] <Measurement method> [Softening point of resin] Using a flow tester (Shimadzu Corporation, CFT-500D), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger, and the sample was 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 was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point.

[0081] [Maximum peak temperature of endothermic resin] Using a differential scanning calorimeter (TA Instruments Japan, Q-100), 0.01 to 0.02 g of the sample was 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 were taken at a heating 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] Using a differential scanning calorimeter (TA Instruments Japan, Q-100), 0.01 to 0.02 g of the sample was 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 was heated again at a rate of 10°C / min, and the endothermic peak was 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 peak's rise to its peak was defined as the glass transition temperature.

[0083] [Acid value of resins] The measurements were performed according to the method of JIS K 0070:1992. However, the measurement solvent was changed from the ethanol and ether mixture specified in JIS K 0070 to an acetone and toluene mixture (acetone:toluene = 1:1 (volume ratio)).

[0084] [Weight-average molecular weight of polyester resin constituting the polyester resin segment] The weight-average molecular weight was determined by gel permeation chromatography (GPC) using the following method. (1) Preparation of sample solution The sample was dissolved in tetrahydrofuran at 40 °C so that the concentration became 0.5 g / 100 mL. Then, this solution was filtered using a PTFE type membrane filter “DISMIC-25JP” (manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 0.20 μm to remove insoluble components, and a sample solution was obtained. (2) Molecular weight measurement Using the following measuring device and analytical column, tetrahydrofuran was used as an eluent and flowed at a flow rate of 1 mL per minute to stabilize the column in a thermostat at 40 °C. Then, 100 μL of the sample solution was injected therein for measurement. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. For the calibration curve at this time, several types of monodisperse polystyrenes (A-500 (5.0×10 2 ), A-1000 (1.01×10 3 ), A-2500 (2.63×10 3 ), A-5000 (5.97×10 3 ), F-1 (1.02×10 4 ), F-2 (1.81×10 4 ), F-4 (3.97×10 4 ), F-10 (9.64×10 4 ), F-20 (1.90×10 5 ), F-40 (4.27×10 5 ), F-80 (7.06×10 5 ), F-128 (1.09×10 6 )) manufactured by Tosoh Corporation were used as standard samples. The values in parentheses indicate the molecular weights. Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation) Analytical column: TSKgel GMHXL + TSKgel G3000HXL (both manufactured by Tosoh Corporation)

[0085] 〔Melting point of the mold release agent〕 Using a differential scanning calorimeter (Q-100, manufactured by TA Instruments Japan), 0.02 g of the sample was weighed into an aluminum pan, heated up to 200 °C, and then cooled from 200 °C to 0 °C at a cooling rate of 10 °C / min. Then, the sample was heated up at a heating rate of 10 °C / min, the heat quantity was measured, and the maximum peak temperature of the endotherm was taken as the melting point.

[0086] [Toner particle volume median particle size (D 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter) • Dispersion: Prepared by dissolving polyoxyethylene (9) lauryl ether (Kao Corporation, Emulgen 109P, HLB (Griffin) = 13.6) in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: 10 mg of the sample was added to 5 mL of the dispersion, dispersed for 1 minute using an ultrasonic disperser (SND Corporation, US-1, output: 80W), then 25 mL of electrolyte was added, and dispersed again for 1 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 ) was sought.

[0087] [Average particle size of external additives] The average particle diameter refers to the number-average particle diameter. This was calculated by measuring the particle size (average of the major and minor axes) of 500 particles from scanning electron microscope (SEM) images and then taking the number-average value of these measurements.

[0088] <Preparation of raw materials> [Manufacturing of binder resins (amorphous composite resins A1-A4)] The alcohol component, carboxylic acid component, esterification catalyst, and esterification co-catalyst shown in Table 1 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 160°C, a sample for confirming the weight-average molecular weight was taken, and the polymethyl methacrylate resin shown in Table 1 was added. The temperature was then gradually increased to 220°C at 10°C / h. The reaction was carried out at 220°C for 2 hours, and then further under reduced pressure of 10 kPa at 220°C until the softening point shown in Table 1 was reached, yielding amorphous composite resins A1 to A4, respectively. The weight-average molecular weight of the alcohol component and carboxylic acid component at the end of polycondensation was 3800. Other physical properties are shown in Table 1.

[0089] [Manufacturing of binder resin (amorphous resin A5)] The alcohol component, carboxylic acid component, esterification catalyst, and esterification co-catalyst shown in Table 1 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 then polycondensation was carried out at 235°C for 6 hours. Subsequently, the reaction was carried out at 235°C under reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding amorphous resin A5. The physical properties are shown in the table.

[0090] [Table 1]

[0091] <Examples and Comparative Examples> [Examples 1-8, Comparative Examples 1-2] The predetermined amounts of binder resin, release agent, polymer-type positive charge control agent (Fujikura Chemical Co., Ltd., FCA-201-PS, softening point: 119°C, glass transition temperature: 65°C), positive charge control agent (Orient Chemical Industry Co., Ltd., Bontron N-79), and colorant (Cabot Co., Ltd., REGAL 330) shown in Table 2 were mixed for 1 minute using a Henschel mixer, and then melt-kneaded under the conditions described below. Co-rotating twin-screw extruder (Ikegai Co., Ltd., PCM-30, shaft diameter 2.9 cm, shaft cross-sectional area 7.06 cm²) 2The following was used: barrel set temperature 100°C, shaft rotation speed 200 r / min (shaft rotation peripheral speed 0.30 m / sec), mixture supply rate 10 kg / h (mixture supply amount per unit cross-sectional area of ​​the shaft 1.42 kg / h·cm). 2 The obtained resin mixture was cooled and coarsely ground using a pulverizer (Rotoplex, manufactured by Hosokawa Micron Corporation), and a coarse pulverized material with a volume median particle size of 2 mm or less was obtained using a sieve with a mesh opening of 2 mm. The obtained coarse pulverized material was then subjected to a DS2 type airflow classifier (impingement plate type, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to determine the volume median particle size (D 50 The material was finely ground by adjusting the grinding pressure so that the particle size was 8.0 μm. The resulting finely ground material was then processed using a DSX2 type airflow classifier (manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to determine the medium particle size (D 50 Classification was performed by adjusting the static pressure (internal pressure) so that the particle size was 7.5 μm, and toner classified products were obtained. 100 parts by mass of the obtained toner classified product and 0.5 parts by mass of hydrophobic silica "TG 820F" (manufactured by Cabot, average particle size: 8 nm) and 1 part by mass of hydrophobic silica "RY50" (manufactured by Nippon Aerosil, hydrophobic treatment agent: average particle size: 40 nm) were mixed in a Henschel mixer at 2100 r / min for 3 minutes to obtain toner.

[0092] <Evaluation Method> [Evaluation of resistance to hot offset] A modified printer (Brother Industries, HL-2040) capable of capturing unfixed images was filled with toner, and the toner deposition amount was measured at 0.40 ± 0.03 mg / cm². 2The printer was adjusted to print a 2.0cm x 2.0cm solid image onto paper (Xerox Vitality). The solid image was removed before passing through the fuser to obtain an unfixed image. Using an external fuser unit modified from an OKI MICROLINE 3010 printer, the fuser roll rotation speed was increased by 10°C increments from 100°C to 220°C while fixing the unfixed image at each temperature to obtain a fixed image. The obtained fixed images were visually inspected, and the highest fuser roll temperature at which no hot offset occurred was defined as the maximum fixing temperature. A higher maximum fixing temperature indicates better resistance to hot offset. The results are shown in Table 2.

[0093] [Durability evaluation] A printer equipped with a cleanerless developing system (Brother Industries, HL-2040) was loaded with toner and left in a 25°C / 50%RH environment for 15 hours. Afterward, 500 pages were printed continuously at 5% print density under the same conditions, and the presence or absence of filming on the photoreceptor was visually checked. If no filming occurred, the evaluation was repeated until a total of 5,000 pages were printed. Table 2 shows the number of pages on which filming was observed. A higher number of pages with filming indicates superior durability. If no streaks were observed even after 5,000 pages, it was indicated as ">5000".

[0094] [Table 2]

[0095] From the results above, it can be seen that the toners of Examples 1 to 8 are toners that can achieve both hot offset resistance and durability.

Claims

1. A toner for developing electrostatic images, comprising toner particles containing a binder resin and a release agent, The amorphous composite resin A comprises a polyester resin segment which is a polycondensate of an alcohol component and a carboxylic acid component, and a polymethacrylic acid ester resin segment which is an addition polymer of raw material monomers containing a methacrylic acid ester. A toner for developing electrostatic images, wherein the release agent contains ester wax.

2. The electrostatic developer toner according to claim 1, wherein the content of the polymethacrylate ester resin segment in the amorphous resin A is 1 part by mass or more and 100 parts by mass or less per 100 parts by mass of the polyester resin segment.

3. The electrostatic developer toner according to claim 1, wherein the content of the ester wax in the toner particles is 0.35 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the amorphous composite resin A.

4. A method for manufacturing electrostatic image developing toner according to any one of claims 1 to 3, A method for producing toner for electrostatic image developing, wherein the amorphous composite resin A is formed by transesterification between a polyester resin and a polymethacrylate ester resin.

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