Method for manufacturing toner for electrostatic image development

Abstract

This relates to a method for manufacturing electrostatic image developing toner with excellent image uniformity. [Solution] A method for manufacturing toner for electrostatic image development, comprising: step 1 of melt-kneading at least a crystalline polyester resin and an amorphous polyester resin; step 2 of grinding the kneaded material obtained in step 1 and then mixing the resulting pulverized material with inorganic fine particles; and step 3 of grinding and classifying the mixture obtained in step 2, wherein the ester group concentration of the crystalline polyester resin is 6.0 mmol / g or more and 9.0 mmol / g or less, the ester group concentration of the amorphous polyester resin is 3.0 mmol / g or more and 10.0 mmol / g or less, and the number-average particle diameter of the inorganic fine particles is 70 nm or more and 150 nm or less.

Description

[Technical Field]

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

[0002] Typically, electrostatic image developing toners undergo an external additive treatment in which inorganic fine particles are attached to the toner surface. However, in order to suppress the embedding or detachment of inorganic fine particles from the toner, a method has been investigated in which coarsely ground compound material is mixed with inorganic fine particles during the toner manufacturing process, and then finely ground, thereby making the inorganic fine particles adhere more firmly to the toner surface (see Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-215403 [Patent Document 2] Japanese Patent Publication No. 2019-159022 [Patent Document 3] Japanese Patent Publication No. 2015-87425 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, conventional toners still require further improvement in terms of image uniformity.

[0005] This invention relates to a method for manufacturing a toner for electrostatic image development that exhibits excellent image uniformity. [Means for solving the problem]

[0006] The present invention relates to a method for producing toner for electrostatic image development, comprising: step 1 of melt-kneading at least a crystalline polyester resin and an amorphous polyester resin; step 2 of pulverizing the kneaded product obtained in step 1 and mixing the resulting pulverized product with inorganic fine particles; and step 3 of pulverizing and classifying the mixture obtained in step 2, wherein the ester group concentration of the crystalline polyester resin is 6.0 mmol / g or more and 9.0 mmol / g or less, the ester group concentration of the amorphous polyester resin is 3.0 mmol / g or more and 10.0 mmol / g or less, and the number-average particle diameter of the inorganic fine particles is 70 nm or more and 150 nm or less. [Effects of the Invention]

[0007] The method of the present invention provides a toner for electrostatic image development with excellent image uniformity. [Modes for carrying out the invention]

[0008] The present invention relates to a method for producing electrostatic image developing toner (hereinafter also referred to as toner) containing crystalline polyester resin and amorphous polyester resin by a melt-kneading method. In this method, a coarsely ground mixture obtained by melt-kneading raw materials containing amorphous polyester resin and crystalline polyester resin having a specific ester group concentration is mixed with large-particle inorganic fine particles, and then finely ground to obtain toner with excellent image uniformity. The reason why toner with excellent image uniformity can be obtained by the method of the present invention is not clear, but it is presumed to be as follows. Note that the following mechanism is a presumption and is not limited thereto.

[0009] In this invention, the raw materials for toner are melted and kneaded, the kneaded mixture is cooled and coarsely ground, and then further finely ground in the presence of inorganic fine particles, thereby enabling the easily aggregated silica fine particles to adhere uniformly to the toner surface. However, when using large-particle inorganic fine particles, which are advantageous for improving the fluidity of the toner, there is a problem that the large-particle inorganic fine particles have a large surface area, making them difficult to embed on the toner surface and therefore prone to detachment. In contrast, the present invention uses amorphous polyester resin and crystalline polyester resin having specific ester group concentrations in the binder resin that forms the toner base. By mixing these two resins, which have ester group concentrations in a similar range, the compatibility between the amorphous and crystalline polyester resins is improved, and the toner base is moderately softened. As a result, large-particle inorganic fine particles are moderately embedded within the toner particles, adhering firmly to the toner surface and effectively creating a spacer effect between the toner particles, further improving the toner's fluidity. Consequently, the uniformity of the printed image is expected to improve.

[0010] The toner manufacturing method of the present invention comprises the following steps 1, 2, and 3.

[0011] Step 1 is a step of melting and kneading at least a crystalline polyester resin and an amorphous polyester resin.

[0012] From the viewpoint of image uniformity, the ester group concentration of the crystalline polyester resin is 6.0 mmol / g or higher, preferably 6.5 mmol / g or higher, more preferably 6.8 mmol / g or higher, and 9.0 mmol / g or lower, preferably 8.0 mmol / g or lower, and more preferably 7.5 mmol / g or lower.

[0013] On the other hand, the ester group concentration of the amorphous polyester resin is 3.0 mmol / g or higher, preferably 3.5 mmol / g or higher, more preferably 3.8 mmol / g or higher, and 10.0 mmol / g or lower, preferably 8.0 mmol / g or lower, and more preferably 6.0 mmol / g or lower, from the viewpoint of image uniformity.

[0014] Furthermore, from the viewpoint of image uniformity, the difference in ester group concentration between the crystalline polyester resin and the amorphous polyester resin is preferably 5.0 mmol / g or less, and more preferably 4.0 mmol / g or less.

[0015] In the present invention, the ester group concentration of the polyester resin is calculated from the following formula. When the crystalline polyester resin and / or the amorphous polyester resin is composed of two or more resins, the weighted average value calculated according to the mass ratio of each resin is taken as the ester group concentration of the crystalline polyester resin or the amorphous polyester resin.

[0016]

Number

[0017] 〔In the formula, A is the total amount of ester bonds (mol) formed when all the raw material monomers of the polyester resin have reacted, and B is the total mass (g) of the raw material monomers constituting the polyester resin. Note that the parentheses in the formula indicate the units of each numerical value.〕

[0018] The crystallinity of the resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum peak temperature of endothermic heat measured by a differential scanning calorimeter, that is, the value of [softening point / maximum peak temperature of endothermic heat]. The crystalline resin has a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and is a resin of 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. On the other hand, the amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index exceeds 1.4, preferably exceeds 1.5, more preferably is 1.6 or more, or is a resin of less than 0.6, preferably 0.5 or less. The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and manufacturing conditions (for example, reaction temperature, reaction time, cooling rate), etc. The maximum peak temperature of endothermic heat refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum peak temperature of endothermic heat is taken as the melting point.

[0019] As a crystalline polyester resin, a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound is preferred. From the viewpoint of low-temperature fixability, it is preferable that the alcohol component contains a short-chain diol having 2 to 6 carbon atoms and / or the carboxylic acid component contains a short-chain aliphatic dicarboxylic acid compound having 4 to 8 carbon atoms.

[0020] The number of carbon atoms in the short-chain aliphatic diol is between 2 and 6, preferably between 2 and 4.

[0021] Examples of short-chain aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-butenediol, and neopentyl glycol.

[0022] When the alcohol component contains a short-chain aliphatic diol, the content of the short-chain aliphatic diol is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less of the alcohol component.

[0023] Other aliphatic diols besides short-chain aliphatic diols include 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol.

[0024] The number of carbon atoms in aliphatic diols other than short-chain aliphatic diols is preferably 8 or more, more preferably 9 or more, and preferably 16 or less, more preferably 14 or less.

[0025] The aliphatic diol content in the alcohol component is preferably 80 mol% or more, more preferably 90 mol% or more, more preferably 95 mol% or more, and 100 mol% or less, from the viewpoint of crystallinity and low-temperature fixability.

[0026] Examples of alcohol components other than aliphatic diols include alkylene oxide adducts of bisphenol A, aromatic diols such as bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trivalent or higher alcohols such as trimethylolpropane, etc.

[0027] Examples of short-chain aliphatic dicarboxylic acid compounds include succinic acid (4 carbon atoms), fumaric acid (4 carbon atoms), adipic acid (6 carbon atoms), suberic acid (8 carbon atoms), anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0028] The number of carbon atoms in the short-chain aliphatic dicarboxylic acid compound is 4 to 8, preferably 4 to 6. Note that the number of carbon atoms in the alkyl group when the aliphatic dicarboxylic acid compound is an alkyl ester is not included in the above carbon number calculation.

[0029] When the carboxylic acid component contains a short-chain aliphatic dicarboxylic acid compound, the content of the short-chain aliphatic dicarboxylic acid compound is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less of the carboxylic acid component.

[0030] Examples of aliphatic dicarboxylic acid compounds other than short-chain aliphatic dicarboxylic acid compounds include azelaic acid (9 carbon atoms), sebacic acid (10 carbon atoms), dodecanediic acid (12 carbon atoms), tetradecanediic acid (14 carbon atoms), anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0031] The carbon number of aliphatic dicarboxylic acid compounds other than short-chain aliphatic dicarboxylic acid compounds is preferably 9 or more, more preferably 10 or more, even more preferably 12 or more, and preferably 18 or less, more preferably 16 or less, and even more preferably 14 or less. Note that the carbon number of the alkyl group when the aliphatic dicarboxylic acid compound is an alkyl ester is not included in the above carbon number.

[0032] The content of aliphatic dicarboxylic acid compounds in the carboxylic acid component is preferably 80 mol% or more, more preferably 90 mol% or more, and 100 mol% or less, preferably 95 mol% or less, from the viewpoint of crystallinity and low-temperature fixability.

[0033] Examples of carboxylic acid components other than aliphatic dicarboxylic acid compounds include aromatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and trivalent or higher carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

[0034] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monohydric carboxylic acid compound, as appropriate. From the viewpoint of improving hydrophobicity, it is preferable that the carboxylic acid component further contains an aliphatic monocarboxylic acid compound.

[0035] Examples of aliphatic monocarboxylic acid compounds include aliphatic monocarboxylic acids such as caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, as well as alkyl esters of these acids in which the alkyl group has 1 to 3 carbon atoms.

[0036] From the viewpoint of hydrophobicity, the carbon number of the aliphatic monocarboxylic acid compound is preferably 6 or more, more preferably 9 or more, and even more preferably 10 or more. From the viewpoint of low-temperature fixability, it is preferably 24 or less, more preferably 23 or less, and even more preferably 22 or less. Here, the carbon number of the alkyl group when the aliphatic monocarboxylic acid compound is an alkyl ester is not included in the above carbon number.

[0037] The content of the aliphatic monocarboxylic acid compound is preferably 2 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, in the carboxylic acid component.

[0038] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol and carboxylic acid components.

[0039] The equivalent ratio of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.8 or higher, more preferably 0.9 or higher, from the viewpoint of electrostatic stability, and preferably 1.2 or lower, more preferably 1.1 or lower, from the viewpoint of low-temperature fixability.

[0040] In the present invention, preferred embodiments of the crystalline polyester resin include: A polycondensate of an alcohol component containing 80 mol% or more of a short-chain aliphatic diol having 2 to 6 carbon atoms and a carboxylic acid component containing 80 mol% or more of an aliphatic dicarboxylic acid compound having 9 to 18 carbon atoms. Polycondensate of an alcohol component containing 80 mol% or more of an aliphatic diol having 8 to 16 carbon atoms and a carboxylic acid component containing 80 mol% or more of a short-chain aliphatic dicarboxylic acid compound having 4 to 8 carbon atoms. These are some examples.

[0041] Crystalline polyester resins can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and optionally in the presence of a co-catalyst, polymerization inhibitor, etc., at a temperature preferably 120°C or higher, more preferably 180°C or higher, and preferably 230°C or lower, more preferably 220°C or lower.

[0042] 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.

[0043] In this invention, the polyester resin may be a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins that have been grafted or blocked with phenol, urethane, epoxy, etc., by methods described in Japanese Patent Publication No. 11-133668, Japanese Patent Publication No. 10-239903, Japanese Patent Publication No. 8-20636, etc. Among modified polyester resins, urethane-modified polyester resins obtained by urethane elongation of polyester resin with a polyisocyanate compound are preferred.

[0044] The softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, from the viewpoint of electrostatic stability, and preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 100°C or lower, from the viewpoint of low-temperature fixability.

[0045] From the viewpoint of storage properties, the melting point of the crystalline polyester resin is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 68°C or higher. From the viewpoint of low-temperature fixability, it is preferably 105°C or lower, more preferably 100°C or lower, and even more preferably 95°C or lower.

[0046] The acid value of the crystalline polyester resin is preferably 2 mg KOH / g or more, more preferably 4 mg KOH / g or more, from the viewpoint of transferability, and preferably 15 mg KOH / g or less, more preferably 12 mg KOH / g or less, from the viewpoint of electrostatic stability.

[0047] The content of crystalline polyester resin is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 12% by mass or less, based on the total amount of crystalline polyester resin and amorphous polyester resin.

[0048] As the amorphous polyester resin, a polycondensate of an alcohol component containing a diol and a carboxylic acid component containing a dicarboxylic acid compound is preferred, and a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing an aromatic dicarboxylic acid compound is more preferred.

[0049] Examples of alkylene oxide adducts of bisphenol A include ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A, and formula (I):

[0050] [ka]

[0051] (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.) Compounds represented by are preferred.

[0052] From the viewpoint of low-temperature fixability, the content of the bisphenol A alkylene oxide adduct is preferably 30 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, and 100 mol% or less, in the alcohol component.

[0053] Other alcohol components include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; diols such as bisphenol A and hydrogenated bisphenol A; and trivalent or higher alcohols such as sorbitol, pentaerythritol, glycerin, and trimethylolpropane.

[0054] 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.

[0055] The content of aromatic dicarboxylic acid compounds is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and preferably 100 mol% or less, more preferably 93 mol% or less, and even more preferably 85 mol% or less, in the carboxylic acid component.

[0056] Other carboxylic acid components include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid, trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids with 1 to 3 carbon atoms.

[0057] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monohydric carboxylic acid compound, as appropriate.

[0058] 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.

[0059] The polycondensation reaction conditions between the alcohol component and the carboxylic acid component of the amorphous polyester resin are the same as those for the crystalline polyester resin, except that the preferred reaction temperature is 130°C or higher, more preferably 170°C or higher, and 250°C or lower, more preferably 240°C or lower.

[0060] The softening point of amorphous polyester resin is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°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.

[0061] The glass transition temperature of amorphous polyester resin is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of electrostatic stability, and preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of low-temperature fixability.

[0062] The acid value of the amorphous polyester resin is preferably 3 mg KOH / g or more, more preferably 5 mg KOH / g or more, from the viewpoint of transferability, and preferably 40 mg KOH / g or less, more preferably 30 mg KOH / g or less, from the viewpoint of electrostatic stability.

[0063] The content of amorphous polyester resin is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 93% by mass or less, based on the total amount of crystalline polyester resin and amorphous polyester resin.

[0064] The mass ratio of crystalline polyester resin to amorphous polyester resin (crystalline polyester resin / amorphous polyester resin) is preferably 2 / 98 or more, more preferably 5 / 95 or more, even more preferably 7 / 93 or more, and preferably 20 / 80 or less, more preferably 15 / 85 or less, and even more preferably 12 / 88 or less.

[0065] Crystalline polyester resins and amorphous polyester resins are used as binders, and other binders include 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.

[0066] The total content of crystalline polyester resin and amorphous polyester resin in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less.

[0067] The binder resin content in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less. Similarly, the total content of crystalline polyester resin and amorphous polyester resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less.

[0068] In step 1, raw materials that can be melt-kneaded together with the crystalline polyester resin and amorphous polyester resin include additives such as colorants, release agents, charge control agents, magnetic powders, flowability improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, and cleaning properties improvers.

[0069] 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.

[0070] From the viewpoint of improving the image density and low-temperature fixability of the toner, the amount of colorant used 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.

[0071] 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.

[0072] 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.

[0073] The amount of release agent used is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, from the viewpoint of low-temperature fixing performance and offset resistance of the toner, as well as dispersibility in the binder resin, per 100 parts by mass of the binder resin.

[0074] 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.

[0075] 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.).

[0076] 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.

[0077] From the viewpoint of the charge stability of the toner, the amount of charge control agent used 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), it 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.

[0078] In step 1, the raw materials to be subjected to melt-kneading may be subjected to kneading all at once or in divided portions, but it is preferable to pre-mix them in a mixer such as a Henschel mixer or ball mill before supplying them to the melt-kneading process.

[0079] For melt mixing, known kneaders such as closed-type kneaders, single-screw or twin-screw extruders, and open-roll type kneaders can be used.

[0080] After step 1, the resulting mixture is cooled appropriately until it reaches a hardness that allows for pulverization, and then subjected to the subsequent step 2. Here, cooling refers to cooling the mixture to 0°C to 50°C, or to a temperature below the glass transition temperature of the binder resin in the mixture.

[0081] Step 2 is a step in which the kneaded material obtained in Step 1 is pulverized, and the resulting pulverized material is mixed with inorganic fine particles. In this specification, the pulverization in Step 2 is also referred to as "coarse pulverization," and the resulting pulverized material is also referred to as "coarse pulverized material."

[0082] Examples of grinders used for coarse grinding include hammer mills, atomizers, and Rotoplexes.

[0083] In coarse grinding, it is preferable to coarsely grind the kneaded material obtained in step 1 until the particle size is approximately 0.1 to 3 mm, then pass it through a sieve with a mesh opening of approximately 2 to 3 mm, and mix the pulverized material that has passed through the sieve with inorganic fine particles as pulverized material with a maximum diameter of 2 to 3 mm or less (coarse pulverized material).

[0084] Examples of inorganic fine particles used in step 2 include particles made of silicon dioxide (silica), titanium dioxide, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, tin oxide, etc. Among these, silica particles or titanium dioxide particles are preferred from the viewpoint of imparting electrostatic charge, and silica particles are more preferred. These can be used individually or as a mixture of two or more.

[0085] Inorganic fine particles are preferably hydrophobized. Examples of hydrophobizing agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), alkylsilane, dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0086] In the present invention, the charge polarity of inorganic fine particles may be positively charged or negatively charged, and is not particularly limited. However, inorganic fine particles can be given a charge polarity opposite to their own by a surface treatment agent. For example, hydrophobic treatment agents such as hexamethyldisilazane (HMDS) and polydimethylsiloxane (PDMS) do not themselves affect the chargeability of inorganic fine particles. However, by introducing a positive charge-imparting group such as an amino group into the hydrophobic treatment agent, negatively charged inorganic fine particles can be given positive chargeability, and by introducing a negative charge-imparting group, positively charged inorganic fine particles can be given negative chargeability.

[0087] The number-average particle diameter of the inorganic fine particles is 70 nm or larger, preferably 75 nm or larger, and more preferably 78 nm or larger, from the viewpoint of toner fluidity, and 150 nm or smaller, preferably 100 nm or smaller, and more preferably 90 nm or smaller, from the viewpoint of suppressing detachment from toner particles.

[0088] The amount of inorganic fine particles used in step 2 is preferably 0.3 parts by mass or more, more preferably 0.8 parts by mass or more, even more preferably 1.2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the coarsely ground material.

[0089] A mixer such as a Henschel mixer can be used to mix the coarse pulverized material and the inorganic fine particles. It is preferable to mix them to the extent that the inorganic fine particles adhere to the surface of the coarse pulverized material.

[0090] Step 3 is the process of grinding and classifying the mixture obtained in Step 2. In this specification, the grinding in Step 3 is also referred to as "fine grinding".

[0091] Examples of grinders used for fine grinding include fluidized bed counter jet mills, impact plate jet mills, and rotary mechanical mills.

[0092] The degree of fine grinding is preferably adjusted as appropriate according to the desired toner particle size.

[0093] Classifiers used for classification include air-flow classifiers, inertial classifiers, and sieve classifiers.

[0094] Furthermore, fine grinding and classification may be performed simultaneously or repeatedly, depending on the specifications of the equipment used and the manufacturing efficiency.

[0095] In the present invention, it is preferable to further perform step 4, in which the classified product obtained in step 3 is mixed with an external additive, from the viewpoint of improving transferability.

[0096] 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.

[0097] 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.

[0098] The number-average particle size of the external additive is preferably 6 nm or larger, more preferably 8 nm or larger, and more preferably 60 nm or smaller, more preferably 40 nm or smaller, and even more preferably 20 nm or smaller, from the viewpoint of the toner's chargeability, fluidity, and transferability.

[0099] 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.

[0100] The amount of external additive used 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 (classified material) before treatment with the external additive, from the viewpoint of the toner's electrostatic properties, fluidity, and transferability.

[0101] The volume median particle size (D) of the toner obtained by the present invention 50 The volume median particle size (D) is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. 50 ) refers to the particle size at which the cumulative volume frequency calculated using volume fractions accounts for 50% when calculated from the smallest particle size. Furthermore, if the toner is treated with an external additive, the volume median particle size of the toner particles before treatment with the external additive is taken as the volume median particle size of the toner.

[0102] The toner obtained by the method of the present invention can be used as a one-component developing toner, or mixed with a carrier to form a two-component developing agent. [Examples]

[0103] 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 the resin and the like were measured by the following methods.

[0104] [Softening point of resin] Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample is heated at a heating rate of 6°C / min while a load of 1.96 MPa is applied by a plunger, and the sample is extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester is plotted against temperature, and the temperature at which half of the sample has flowed out is defined as the softening point.

[0105] [Maximum peak temperature of endothermic resin] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a rate of 10°C / min, and maintained at 0°C for 1 minute. Then, measurements are taken at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area is defined as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is defined as the melting point.

[0106] [Glass transition temperature of resins] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Next, the sample is heated again at a rate of 10°C / min, and the endothermic peak is measured. The temperature at the intersection of the baseline extension below the maximum endothermic peak temperature and the tangent line showing the maximum slope from the rise of the peak to the peak apex is defined as the glass transition temperature.

[0107] [Acid value of resins] Measurements will be performed according to the method of JIS K 0070:1992. However, the measurement solvent will be changed from the ethanol and ether mixed solvent specified in JIS K 0070 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[0108] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample is weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. Next, the sample is heated again at a rate of 10°C / min, the amount of heat is measured, and the maximum peak temperature of endothermic heating is defined as the melting point.

[0109] [Number average particle size of inorganic fine particles and external additives mixed with coarsely ground material] The particle size (average of major and minor axes) of 500 particles (primary particles) is measured from scanning electron microscope (SEM) images, and the numerical average of these values ​​is used.

[0110] [Toner volume medium particle size (D 50 )〕 • Measuring instrument: "Coulter Multisizer (Registered Trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust the concentration to 5% by mass. • Dispersion conditions: Add 10 mg of the sample to 5 mL of the dispersion and disperse for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80W). Then, add 25 mL of electrolyte and disperse for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, the 30,000 particles are measured, and the volume median particle size (D) is determined from the particle size distribution. 50 )

[0111] Production Example 1 of Alkenyl Succinic Anhydride (1) Using propylene tetramer (manufactured by Nippon Oil Corporation, trade name: "Light Tetramer"), alkylene compound (a) was obtained by fractional distillation under heating conditions of 183 to 208°C. The obtained alkylene compound (a) had 40 peaks in gas chromatography-mass spectrometry, as described later. The distribution of the alkylene compound was measured according to the analysis of alkylene compound A by mass spectrometry gas chromatography described in Japanese Patent Publication No. 2014-013384, and C9H 18 :0.5% by mass, C 10 H20 : 4 mass%, C 11 H 22 : 20 mass%, C 12 H 24 : 66 mass%, C 13 H 26 : 9 mass%, C 14 H 28 : 0.5 mass% (the number of peaks corresponding to an alkylene compound having 9 to 14 carbon atoms was 6).

[0112] (2) 542.4 g of alkylene compound (a), 157.2 g of maleic anhydride, 0.4 g of antioxidant "Chellex - O" (manufactured by SC Organic Chemicals Co., Ltd., Triisooctyl phosphite), and 0.1 g of butylhydroquinone as a polymerization inhibitor were charged into a 1 L autoclave manufactured by Nitto Koki Co., Ltd. The pressure replacement with pressurized nitrogen (0.2 MPaG) was repeated three times. After starting stirring at 60°C, the temperature was raised to 230°C over 1 hour and the reaction was carried out for 6 hours. The pressure at the time of reaching the reaction temperature was 0.3 MPaG. After the reaction was completed, it was cooled to 80°C, returned to normal pressure (101.3 kPa), and transferred to a 1 - liter four - neck flask. The temperature was raised to 180°C with stirring, and the remaining alkylene compound was distilled off at 1.3 kPa over 1 hour. Subsequently, after cooling to room temperature (25°C) and returning to normal pressure (101.3 kPa), 406.1 g of the target alkenyl succinic anhydride A was obtained. The average molecular weight of alkenyl succinic anhydride A determined from the acid value was 268.

[0113] Resin Production Example 1 The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst, and co - catalyst shown in Table 1 were placed in a 10 - liter four - neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple. After raising the temperature to 235°C under a nitrogen atmosphere, polycondensation was carried out at 235°C for 6 hours. Then, the temperature was lowered to 210°C, trimellitic anhydride was added, and after reacting at 210°C for 1 hour, the reaction was further carried out at 210°C under a reduced pressure of 10 kPa until the softening point described in Table 1 was reached to obtain an amorphous polyester resin (Resin AH1). The physical properties are shown in Table 1.

[0114] Resin Production Example 2 The alcohol components, carboxylic acid components other than trimellitic anhydride and fumaric acid, esterification catalyst, and co-catalyst shown in Table 1 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the mixture was held at 180°C for 1 hour, then the temperature was increased from 180°C to 235°C at a rate of 10°C / h, and polycondensation was carried out at 235°C for 5 hours. After that, the temperature was lowered to 180°C, and trimellitic anhydride, fumaric acid, and polymerization inhibitor shown in Table 1 were added. After reacting at 180°C for 1 hour, the temperature was increased from 180°C to 210°C at a rate of 10°C / h, and polycondensation was carried out at 210°C for another 1 hour. After that, the reaction was carried out at 210°C under reduced pressure of 10 kPa until the softening point shown in the table was reached, yielding amorphous polyester resin (resin AH2). The physical properties are shown in Table 1.

[0115] Resin manufacturing example 3 The alcohol component, carboxylic acid component, esterification catalyst, and co-catalyst shown in Table 1 were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. The mixture was heated to 180°C and held for 1 hour under a nitrogen atmosphere. Subsequently, the temperature was increased from 180°C to 230°C at a rate of 10°C / h, followed by a polycondensation reaction at 230°C for 6 hours. The reaction was then carried out at 230°C under reduced pressure of 8 kPa until the softening point shown in Table 1 was reached, yielding an amorphous polyester resin (resin AH3). The physical properties are shown in Table 1.

[0116] [Table 1]

[0117] Resin manufacturing example 4 The alcohol and carboxylic acid components shown in Table 2 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-through condenser, and a nitrogen inlet tube. The mixture was heated to 200°C over 8 hours in a mantle heater under a nitrogen atmosphere. Subsequently, the esterification catalyst shown in Table 2 was added, and the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, yielding crystalline polyester resins (resins C1-C4, C7). The physical properties are shown in Table 2.

[0118] Resin manufacturing example 5 The alcohol component, carboxylic acid component, and polymerization inhibitor shown in Table 2 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-through condenser, and a nitrogen inlet tube. The mixture was heated to 200°C over 8 hours in a mantle heater under a nitrogen atmosphere. Subsequently, the esterification catalyst shown in Table 2 was added, and the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, yielding crystalline polyester resins (resins C5 and C6). The physical properties are shown in Table 2.

[0119] [Table 2]

[0120] Examples 1-11 and Comparative Examples 1 and 2 90 parts by mass of amorphous polyester resin, 10 parts by mass of crystalline polyester resin, 2.0 parts by mass of the release agent "WE-14" (manufactured by NOF Corporation, ester wax, melting point: 79°C), 10 parts by mass of the polymer-type positive charge control agent "FCA-201-PS" (manufactured by Fujikura Chemicals, Inc., softening point: 119°C, glass transition temperature: 65°C), 1.0 part by mass of the positive charge control agent "Bontron N-79" (manufactured by Orient Chemical Industries, Ltd.), and 6 parts by mass of the coloring agent "REGAL 330" (manufactured by Cabot Corporation, carbon black) were mixed for 1 minute using a Henschel mixer, and then melt-kneaded under the conditions shown below.

[0121] Co-rotating twin-screw extruder "PCM-30" (manufactured by Ikegai Co., Ltd., shaft diameter 2.9 cm, shaft cross-sectional area 7.06 cm²) 2 The 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 ) was.

[0122] The resulting mixture is cooled and coarsely ground using a Rotoplex pulverizer (manufactured by Hosokawa Micron Corporation), and the medium volume particle size (D) is measured using a sieve with a mesh size of 2 mm. 50 A coarse pulverized material with particles of 2 mm or less was obtained. 100 parts by mass of the obtained coarse pulverized material and 2 parts by mass of inorganic fine particles shown in Table 4 were mixed in a Henschel mixer for 2 minutes to obtain a coarse pulverized material with the inorganic fine particles attached.

[0123] Coarsely ground material with attached inorganic fine particles is processed using an IDS2 type jet mill (impact plate type, manufactured by Nippon Pneumatic Co., Ltd.) to obtain a volume-intermediate particle size (D 50 The material was finely ground by adjusting the grinding pressure so that the particle size was 8.0 μm. Furthermore, using a DS2 type airflow classifier (manufactured by Nippon Pneumatic Co., Ltd.), the static pressure (internal pressure) was adjusted so that the median volume particle size was 7.5 μm, and classification was performed to obtain toner particles.

[0124] Toner was obtained by mixing 100 parts by mass of the obtained toner particles with 0.8 parts by mass of hydrophobic silica "TG-820F" (manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS and cyclic silazane, number average particle size: 8 nm) as an external additive in a Henschel mixer at 2100 r / min (peripheral speed 29 m / sec) for 3 minutes.

[0125] Comparative Example 3 In Example 1, toner was obtained in the same manner as in Example 1, except that the coarsely ground material was not mixed with inorganic fine particles, but was instead finely ground and classified as is.

[0126] The details of the inorganic fine particles mixed with the coarsely ground material in the examples and comparative examples are as follows.

[0127] [Table 3]

[0128] Test example [Image uniformity] Toner was mounted on the non-magnetic single-component developer "OKI MICROLINE 5400" (manufactured by Oki Electric Industry Co., Ltd.), and 100 sheets of 100% solid color images were continuously printed on high-quality paper "J Paper A4 size" (manufactured by Fujifilm Business Innovation Co., Ltd.) in A4 portrait orientation. For the 100th solid color image, the color density was measured at five equally spaced locations using X-Rite eXact (manufactured by X-Rite), and the difference between the maximum and minimum image density (density difference) was determined as image uniformity. The results are shown in Table 4.

[0129] [Table 4]

[0130] Based on these results, it can be seen that the toners of Examples 1 to 11 exhibit superior image uniformity compared to Comparative Example 1, in which the particle size of the inorganic fine particles mixed with the coarsely ground material in Step 2 was too small; Comparative Example 2, in which the ester group concentration of the crystalline polyester resin was too low; and Comparative Example 3, in which no inorganic fine particles were used in Step 2. [Industrial applicability]

[0131] The electrostatic image developing toner obtained by the method of the present invention is suitably used for developing latent images formed in electrostatic image developing methods, electrostatic recording methods, electrostatic printing methods, and the like.

Claims

1. A method for producing toner for electrostatic image development, comprising: step 1 of melt-kneading at least a crystalline polyester resin and an amorphous polyester resin; step 2 of pulverizing the kneaded product obtained in step 1 and mixing the resulting pulverized product with inorganic fine particles; and step 3 of pulverizing and classifying the mixture obtained in step 2, wherein the ester group concentration of the crystalline polyester resin is 6.0 mmol / g or more and 9.0 mmol / g or less, the ester group concentration of the amorphous polyester resin is 3.0 mmol / g or more and 10.0 mmol / g or less, and the number-average particle diameter of the inorganic fine particles is 70 nm or more and 150 nm or less.

2. A method for producing a toner for electrostatic image developing according to claim 1, wherein the crystalline polyester resin is a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, wherein the alcohol component contains a short-chain diol having 2 to 6 carbon atoms and / or the carboxylic acid component contains a short-chain aliphatic dicarboxylic acid compound having 4 to 8 carbon atoms.

3. A method for producing electrostatic image developing toner according to claim 1 or 2, wherein the inorganic fine particles are silica particles.

4. A method for producing a toner for electrostatic image developing according to claim 1 or 2, wherein the ester group concentration of the amorphous polyester resin is 3.0 mmol / g or more and 8.0 mmol / g or less.

5. A method for producing electrostatic image developing toner according to claim 1 or 2, wherein the number-average particle size of the inorganic fine particles is 70 nm or more and 100 nm or less.

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