Method for manufacturing toner for electrostatic charge image development

Abstract

To provide a method for manufacturing a toner for electrostatic charge image development which is excellent in all of glossiness of a printed surface and document offset resistance during storage under high temperature.SOLUTION: A method for manufacturing a toner for electrostatic charge image development includes a step 1 of melting and kneading at least an amorphous resin and a crystalline polyester resin using an open roll type kneader, a step 2 of crushing a kneaded product obtained in the step 1, and then mixing the obtained crushed product with inorganic particles, and a step 3 of crushing the mixture obtained in the step 2, and classifying the mixture, wherein the crystalline polyester resin is a polycondensate of an alcohol component containing aliphatic diol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, the alcohol component contains short chain aliphatic diol having 2 or more and 6 or less carbon atoms and / or the carboxylic acid component contains a short chain aliphatic dicarboxylic acid compound having 4 or more and 8 or less carbon atoms.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] With the development of electrophotographic systems, there is a demand for the development of electrostatic charge image developing toners (hereinafter, also simply referred to as "toners") that can cope with higher image quality and higher speeds. For example, due to the higher speed of the machine, the amount of heat applied to the toner coated on the recording paper during fixing decreases, so the toner is required to have excellent low-temperature fixability.

[0003] Therefore, as a binder resin for the toner, it is known that a crystalline polyester resin is effective in improving the low-temperature fixability of the toner, and its combined use with an amorphous polyester resin has been studied (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] A toner containing a crystalline polyester resin is excellent in the glossiness of the printed surface because the toner can be quickly plasticized and deformed in the heat fixing process. On the other hand, when the printed matter is stored at a high temperature, when the toner forming the printed layer is plasticized, a phenomenon (document offset) occurs in which a part of the toner migrates to the back surface when other papers are overlapped, and there is a problem of soiling other papers.

[0006] The present invention relates to a method for producing a toner for developing electrostatic images, which has excellent glossiness of a printed surface and excellent resistance to document offset during storage at high temperatures. [Means for solving the problem]

[0007] The present invention relates to a method for producing a toner for developing electrostatic images, the method including step 1 of melt-kneading at least an amorphous resin and a crystalline polyester resin using an open-roll type kneader, step 2 of pulverizing the kneaded product obtained in step 1 and then mixing the pulverized product with inorganic fine particles, and step 3 of pulverizing and classifying the mixture obtained in step 2, wherein the crystalline polyester resin is a polycondensate of an alcohol component containing 80 mol % or more of an aliphatic diol and a carboxylic acid component containing 80 mol % or more of an aliphatic dicarboxylic acid compound, the alcohol component contains a short-chain aliphatic 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, and the mass ratio of the crystalline polyester resin to the amorphous resin is 2 / 98 or more and 18 / 82 or less. Effect of the Invention

[0008] According to the method of the present invention, a toner for developing electrostatic images which is excellent in both the glossiness of the printed surface and the resistance to document offset during storage at high temperatures can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention is a method for obtaining a toner for developing electrostatic images by mixing a coarsely pulverized product of the kneaded product with inorganic fine particles and then finely pulverizing the product when producing a toner containing an amorphous resin and a crystalline polyester resin by a melt kneading method. The reason why the method of the present invention can obtain a toner excellent in both gloss of the printed surface and document offset resistance during storage at high temperatures is not clear, but is presumed to be as follows. Note that the following mechanism is presumed and is not limited thereto.

[0010] In the present invention, by using a crystalline polyester resin containing a short-chain aliphatic diol and / or a short-chain aliphatic dicarboxylic acid-based compound, the ester groups in the resin are in close proximity to each other, and the affinity with the amorphous resin is improved. Further, by melt-kneading a raw material containing an amorphous resin and a crystalline polyester resin using an open-roll type kneader, the dispersibility of the crystalline polyester resin in the amorphous resin is improved. As a result, the obtained toner is easily plasticized during heat fixing and can be sufficiently deformed even with a small amount of heat energy, so that the printed surface is likely to be smooth and the glossiness is improved. Here, since the printed toner is still easily plasticized by heat, when the printed matter is stored at a high temperature, the printed matters adhere to each other and color transfer is likely to occur. However, in the method of the present invention, after the kneaded product is roughly pulverized, it is further pulverized in the presence of inorganic fine particles, so that the inorganic fine particles can be uniformly and firmly adhered to the toner surface. It is considered that the inorganic fine particles fixed to the toner surface function as spacers even after printing, making it difficult for the printed matters to stick to each other and suppressing document offset.

[0011] The method for producing the toner of the present invention includes the following steps 1, 2, and 3.

[0012] Step 1 is a step of melt-kneading at least an amorphous resin and a crystalline polyester resin using an open-roll type kneader.

[0013] Examples of the amorphous resin include amorphous polyester resins, vinyl resins such as styrene-acrylic resins, amorphous epoxy resins, amorphous polycarbonates, amorphous polyurethanes, and composite resins containing two or more of these resins. Among these, from the viewpoint of low-temperature fixability, an amorphous polyester resin is preferred.

[0014] As the amorphous polyester resin, a polycondensate of an alcohol component containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component containing an aromatic dicarboxylic acid-based compound is preferred.

[0015] Examples of the alkylene oxide adduct of bisphenol A include the ethylene oxide adduct of bisphenol A, the propylene oxide adduct of bisphenol A, etc. Formula (I):

[0016] [Chemical formula]

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

[0018] From the viewpoint of low-temperature fixing property, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, and even more preferably 100 mol%.

[0019] Examples of other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and polyhydric alcohols such as trimethylolpropane with 3 or more valences.

[0020] 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.

[0021] The content of the aromatic dicarboxylic acid compound in the carboxylic acid component is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and 100 mol% or less.

[0022] Examples of other carboxylic acid components include aliphatic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, and sebacic acid; polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; anhydrides of these acids; and alkyl esters of these acids having 1 to 3 carbon atoms.

[0023] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0024] In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and the carboxylic acid component.

[0025] The equivalent ratio (COOH group / OH group) of the carboxy group of the carboxylic acid component to the hydroxy group of the alcohol component is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.8 or more, and preferably 1.3 or less, more preferably 1.2 or less, from the viewpoint of adjusting the softening point of the polyester resin.

[0026] The amorphous polyester resin 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 further, if necessary, in the presence of a cocatalyst, a polymerization inhibitor, etc., at a temperature preferably of 160°C or higher, more preferably 200°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

[0027] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropoxybis(triethanolamineate). The amount of the esterification catalyst used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, and preferably 1.5 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the co-catalyst for the esterification catalyst include gallic acid. The amount of the co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0028] In the present invention, the polyester resin may be a polyester resin modified to such an extent that its properties are not substantially impaired. Examples of the modified polyester resin include polyester resins grafted or blocked with phenol, urethane, epoxy, etc. by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Among the modified polyester resins, a urethane-modified polyester resin obtained by extending a polyester resin with a polyisocyanate compound is preferred.

[0029] From the viewpoint of charge stability, the softening point of the amorphous resin is preferably 70°C or higher, more preferably 90°C or higher, still more preferably 100°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 170°C or lower, more preferably 160°C or lower, still more preferably 150°C or lower.

[0030] Note that 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 endotherm measured by a differential scanning calorimeter, i.e., [softening point / maximum peak temperature of endotherm]. 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 less than 0.6, preferably 0.5 or less. On the other hand, the crystallinity index of the crystalline resin is 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and is 1.4 or less, preferably 1.2 or less, more preferably 1.1 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. Note that the maximum peak temperature of endotherm refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum peak temperature of endotherm is taken as the melting point.

[0031] From the viewpoint of charge stability, the glass transition temperature of the amorphous resin is preferably 40°C or higher, more preferably 50°C or higher, and from the viewpoint of low-temperature fixing property, it is preferably 80°C or lower, more preferably 70°C or lower.

[0032] The content of the amorphous resin is preferably 82% by mass or more, more preferably 85% by mass or more, still more preferably 88% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, still more preferably 93% by mass or less in the total amount of the amorphous resin and the crystalline polyester resin.

[0033] The crystalline polyester resin is a polycondensate of an alcohol component containing 80 mol% or more of an aliphatic diol and a carboxylic acid component containing 80 mol% or more of an aliphatic dicarboxylic acid compound, and the alcohol component contains a short-chain aliphatic diol and / or the carboxylic acid component contains a short-chain aliphatic dicarboxylic acid compound.

[0034] Among the alcohol components, 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, neopentyl glycol, and the like.

[0035] The number of carbon atoms of the short-chain aliphatic diol is 2 or more and 6 or less, preferably 2 or more and 4 or less.

[0036] 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, still more preferably 95 mol% or more, and even more preferably 100 mol% in the alcohol component.

[0037] Examples of aliphatic diols other than short-chain aliphatic diols include 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and the like.

[0038] The number of carbon atoms of the aliphatic diol other than the short-chain aliphatic diol is preferably 8 or more, more preferably 10 or more, and preferably 16 or less, more preferably 14 or less.

[0039] From the viewpoints of low-temperature fixing property and glossiness of the printed surface, the content of the aliphatic diol is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 100 mol% in the alcohol component.

[0040] 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, and polyhydric alcohols having a trivalent or higher valency such as trimethylolpropane.

[0041] In the carboxylic acid component, examples of the short-chain aliphatic dicarboxylic acid compounds include succinic acid (number of carbon atoms: 4), fumaric acid (number of carbon atoms: 4), adipic acid (number of carbon atoms: 6), suberic acid (number of carbon atoms: 8), anhydrides of these acids, alkyl esters of these acids having 1 to 3 carbon atoms in the alkyl group, and the like.

[0042] The number of carbon atoms of the short-chain aliphatic dicarboxylic acid compounds is 4 or more and 8 or less, preferably 4 or more and 6 or less. When the aliphatic dicarboxylic acid compound is an alkyl ester, the number of carbon atoms of the alkyl group is not included in the above number of carbon atoms.

[0043] 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, still more preferably 95 mol% or more, and still more preferably 100 mol% in the carboxylic acid component.

[0044] Examples of the aliphatic dicarboxylic acid compounds other than the short-chain aliphatic dicarboxylic acid compounds include azelaic acid (number of carbon atoms: 9), sebacic acid (number of carbon atoms: 10), dodecanedioic acid (number of carbon atoms: 12), tetradecanedioic acid (number of carbon atoms: 14), anhydrides of these acids, alkyl esters of these acids having 1 to 3 carbon atoms in the alkyl group, and the like.

[0045] The number of carbon atoms of the aliphatic dicarboxylic acid compounds other than the short-chain aliphatic dicarboxylic acid compounds is preferably 9 or more, more preferably 10 or more, and preferably 18 or less, more preferably 16 or less, still more preferably 14 or less. When the aliphatic dicarboxylic acid compound is an alkyl ester, the number of carbon atoms of the alkyl group is not included in the above number of carbon atoms.

[0046] The content of the aliphatic dicarboxylic acid compounds is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 100 mol% in the carboxylic acid component from the viewpoints of durability and gloss of the printed surface.

[0047] 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 polyvalent carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

[0048] The alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monohydric carboxylic acid compound.

[0049] 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, a 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 and the like.

[0050] The equivalent ratio of the carboxy group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.8 or more, more preferably 0.9 or more, from the viewpoint of charge stability, and preferably 1.2 or less, more preferably 1.1 or less, from the viewpoint of low-temperature fixability.

[0051] The polycondensation reaction conditions of the alcohol component and the carboxylic acid component of the crystalline polyester resin are the same as those of the amorphous polyester resin, except that the preferred reaction temperature is 120°C or higher, more preferably 180°C or higher, and 230°C or lower, more preferably 220°C or lower.

[0052] The softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 65°C or higher, still more preferably 70°C or higher, from the viewpoint of charge stability, and preferably 120°C or lower, more preferably 110°C or lower, still more preferably 100°C or lower, from the viewpoint of low-temperature fixability.

[0053] From the viewpoint of storage stability, the melting point of the crystalline polyester resin is preferably 60°C or higher, more preferably 65°C or higher, still more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 105°C or lower, more preferably 100°C or lower, still more preferably 95°C or lower.

[0054] The content of the crystalline polyester resin is preferably 2% by mass or more, more preferably 5% by mass or more, still more preferably 7% by mass or more, and preferably 18% by mass or less, more preferably 15% by mass or less, still more preferably 12% by mass or less in the total amount of the amorphous resin and the crystalline polyester resin.

[0055] The mass ratio of the crystalline polyester resin to the amorphous resin (crystalline polyester resin / amorphous resin) is 2 / 98 or more, preferably 5 / 95 or more, more preferably 7 / 93 or more from the viewpoints of low-temperature fixability and glossiness of the printed surface, and 18 / 82 or less, preferably 15 / 85 or less, more preferably 12 / 88 or less from the viewpoints of durability and glossiness of the printed surface.

[0056] The content of the amorphous resin and the crystalline polyester resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more in the toner, and preferably less than 100% by mass, more preferably 98% by mass or less, still more preferably 95% by mass or less.

[0057] In the present invention, the amorphous resin and the crystalline polyester resin are used as a binder resin.

[0058] The total content of the amorphous resin and the crystalline polyester resin is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass in the binder resin.

[0059] The content of the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and preferably less than 100% by mass, more preferably 98% by mass or less, still more preferably 95% by mass or less in the toner.

[0060] In step 1, examples of the raw materials that can be melt-kneaded together with the amorphous resin and the crystalline polyester resin include colorants, mold release agents, charge control agents, magnetic powders, fluidity improvers, conductivity regulators, reinforcing fillers such as fibrous substances, antioxidants, and additives such as cleaning property improvers.

[0061] As the colorant, dyes, pigments, magnetic substances, etc. that are used as colorants for toners can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. may be mentioned. In the present invention, the toner may be either a black toner or a color toner.

[0062] From the viewpoint of improving the image density and low-temperature fixability of the toner, the amount of the 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, still more preferably 10 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0063] Examples of the mold release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and their oxides; ester waxes such as carnauba wax, montan wax, and their deacidified waxes, fatty acid ester waxes; fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts, etc. These can be used alone or in combination of two or more.

[0064] From the viewpoint of the transferability of the toner, the melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 160°C or lower, more preferably 140°C or lower, still more preferably 120°C or lower, and even more preferably 110°C or lower.

[0065] From the viewpoints of the low-temperature fixability and offset resistance of the toner and the dispersibility in the binder resin, the amount of the release agent used is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 1.5 parts by mass or more, based on 100 parts by mass of the binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 7 parts by mass or less.

[0066] The charge control agent is not particularly limited, and may contain either a positively chargeable charge control agent or a negatively chargeable charge control agent.

[0067] Examples of the positively chargeable 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", "Bontron N-79" (manufactured by Orient Chemical Industries, Ltd.); triphenylmethane dyes containing a tertiary amine in the side chain; quaternary ammonium salt compounds such as "Bontron P-51" (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, "COPY CHARGE PX VP435" (manufactured by Clariant); polyamine resins such as "AFP-B" (manufactured by Orient Chemical Industries, Ltd.); imidazole derivatives such as "PLZ-2001", "PLZ-8001" (manufactured by Shikoku Kasei Kogyo Co., Ltd.); styrene-acrylic resins such as "FCA-701PT", "FCA-201-PS" (manufactured by Fujikura Kasei Co., Ltd.).

[0068] In addition, examples of the negative charge control agent include metal-containing azo dyes such as "Vari Fast Black 3804", "Bontron S-31", "Bontron S-32", "Bontron S-34", "Bontron S-36" (manufactured by Orient Chemical Industries, Ltd.), "Eisen Spiron Black TRH", "T-77" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; metal compounds of benzoic acid compounds such as "LR-147", "LR-297" (manufactured by Nippon Carlit Co., Ltd.), etc.; metal compounds of salicylic acid compounds such as "Bontron E-81", "Bontron E-84", "Bontron E-88", "Bontron E-304" (manufactured by Orient Chemical Industries, Ltd.), "TN-105" (manufactured by Hodogaya Chemical Co., Ltd.), etc.; copper phthalocyanine dyes; quaternary ammonium salts such as "COPY CHARGE NX VP434" (manufactured by Clariant), nitroimidazole derivatives, etc.; and organometallic compounds.

[0069] From the viewpoint of the charging stability of the toner, the amount of the charge control agent used is preferably 0.01 part by mass or more, more preferably 0.2 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less, based on 100 parts by mass of the binder resin.

[0070] In Step 1, the raw materials to be melt-kneaded are preferably premixed by a Henschel mixer or the like and then supplied to an open roll type kneader.

[0071] The open roll type kneader refers to a kneader in which the kneading part is not sealed but open, and can easily dissipate the kneading heat generated during melt-kneading. The open roll type kneader used in the present invention is provided with a raw material supply port and a kneaded product discharge port provided along the axial direction of the roll, and from the viewpoint of production efficiency, it is preferably a continuous open roll type kneader.

[0072] The open roll kneader used in the present invention is preferably a kneader equipped with two rolls having different peripheral speeds, that is, a roll with a high peripheral speed (high rotation roll) and a roll with a low peripheral speed (low rotation roll). In the present invention, from the viewpoint of the dispersibility of the kneaded product, it is preferable that the high rotation roll functions as a heating roll and the low rotation roll functions as a cooling roll, that is, it is preferable that the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll. When the set temperatures of the rolls are different on the raw material input side and the kneaded product discharge side, it is preferable that at least on the raw material input side, the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll, and it is more preferable that on both the raw material input side and the kneaded product discharge side, the set temperature of the high rotation roll is higher than the set temperature of the low rotation roll.

[0073] The temperature of the roll can be adjusted, for example, by the temperature of the heat medium passed through the inside of the roll, and each roll may be divided into two or more parts inside the roll and passed through heat media with different temperatures.

[0074] From the viewpoint of reducing the mechanical force during melt kneading and suppressing heat generation, the temperature on the raw material input side of the high rotation roll is preferably 100 °C or higher, more preferably 120 °C or higher, and preferably 160 °C or lower, more preferably 150 °C or lower. From the same viewpoint, the temperature on the raw material input side of the low rotation roll is preferably 25 °C or higher, more preferably 40 °C or higher, and preferably 90 °C or lower, more preferably 80 °C or lower.

[0075] It is preferable that the temperature on the raw material input side is higher than that on the kneaded product discharge side for both the high rotation roll and the low rotation roll. The temperature difference between the raw material input side and the kneaded product discharge side is preferably 20 °C or higher, more preferably 30 °C or higher, and preferably 60 °C or lower, more preferably 50 °C or lower, from the viewpoint of preventing the kneaded product from detaching from the roll and reducing the mechanical force and suppressing heat generation during melt kneading.

[0076] The temperature on the raw material input side of the high-speed roll and the low-speed roll refers to the set temperature at the end of the raw material input side, and the temperature on the kneaded material discharge side refers to the set temperature at the end of the kneaded material discharge side, respectively.

[0077] From the perspective of reducing the mechanical force during kneading and suppressing heat generation, the peripheral speed of the high-speed roll is preferably 2 m / min or more, more preferably 10 m / min or more, still more preferably 25 m / min or more, and is preferably 100 m / min or less, more preferably 75 m / min or less, still more preferably 50 m / min or less. From the same perspective, the peripheral speed of the low-speed roll is preferably 1 m / min or more, more preferably 5 m / min or more, still more preferably 15 m / min or more, and is preferably 90 m / min or less, more preferably 60 m / min or less, still more preferably 30 m / min or less. Also, the ratio of the peripheral speeds of the two rolls (low-speed roll / high-speed roll) is preferably 1 / 10 or more, more preferably 3 / 10 or more, and is preferably 9.9 / 10 or less, more preferably 8 / 10 or less.

[0078] Also, there are no particular limitations on the structure, size, material, etc. of each roll. The roll surface has grooves used for kneading, and examples of this shape include linear, spiral, corrugated, concave-convex, etc.

[0079] After step 1, the obtained kneaded material is appropriately cooled until it reaches a hardness that can be pulverized, and then is subjected to subsequent step 2. Here, cooling means cooling the kneaded material to 0°C to 50°C, or cooling it to below the glass transition temperature of the binder resin in the kneaded material.

[0080] Step 2 is a step of pulverizing the kneaded material obtained in step 1 and then mixing the obtained pulverized material with inorganic fine particles. In this specification, the pulverization in step 2 is also referred to as "coarse pulverization", and the obtained pulverized material is also referred to as "coarse pulverized material".

[0081] Examples of the pulverizer used for coarse pulverization include hammer mills, atomizers, rotorplexes, etc.

[0082] In coarse pulverization, the kneaded product obtained in Step 1 is appropriately coarsely pulverized until the particle size becomes about 0.1 to 3 mm, and then passed through a sieve with an opening of about 2 to 3 mm. The pulverized product passing through the sieve is preferably mixed with inorganic fine particles as a pulverized product (coarse pulverized product) having a maximum diameter of 2 to 3 mm or less.

[0083] Examples of the inorganic fine particles used in Step 2 include silicon dioxide (silica), titanium dioxide, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, tin oxide, etc. Among these, from the viewpoint of imparting chargeability, silica or titanium dioxide is preferable, silica is more preferable, and hydrophobized silica is even more preferable. These can be used alone or in combination of two or more.

[0084] Examples of the hydrophobizing agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), methyltriethoxysilane, etc.

[0085] From the viewpoints of the chargeability, fluidity, and durability of the toner, the average particle diameter of the inorganic fine particles is preferably 5 nm or more, more preferably 7 nm or more, and preferably 40 nm or less, more preferably 20 nm or less.

[0086] From the viewpoints of the glossiness of the printed surface and the resistance to document offset during storage at high temperature, the amount of the inorganic fine particles used in Step 2 is preferably 0.3 part by mass or more, more preferably 0.8 part by mass or more, still more preferably 1.2 part by mass or more, based on 100 parts by mass of the coarsely pulverized product, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 5 parts by mass or less.

[0087] For mixing the coarsely pulverized product and the inorganic fine particles, a mixer such as a Henschel mixer can be used. It is preferable to mix until the inorganic fine particles adhere to the surface of the coarsely pulverized product.

[0088] Step 3 is a step of pulverizing and classifying the mixture obtained in Step 2. In this specification, the pulverization in Step 3 is also referred to as "fine pulverization".

[0089] Examples of the pulverizer used for fine pulverization include a fluidized bed counter jet mill, a collision plate jet mill, a rotary mechanical mill, and the like.

[0090] The degree of fine pulverization is preferably adjusted as appropriate according to the target toner particle size.

[0091] Examples of the classifier used for classification include an air classifier, an inertial classifier, a sieve classifier, and the like.

[0092] Note that fine pulverization and classification may be performed simultaneously or repeatedly according to the specifications of the equipment used and the manufacturing efficiency.

[0093] In the present invention, from the viewpoint of improving transferability, it is preferable to perform Step 4 of mixing the classified product obtained in Step 3 with an external additive.

[0094] 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. Two or more kinds may be used in combination. Among these, silica is preferable, and hydrophobic silica subjected to a hydrophobization treatment is more preferable from the viewpoint of the transferability of the toner.

[0095] Examples of the hydrophobization treatment agent for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), methyltriethoxysilane, and the like.

[0096] The average particle diameter 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 still more preferably 90 nm or less, from the viewpoints of the chargeability, fluidity, and transferability of the toner.

[0097] The external addition treatment by mixing the toner particles and the external additive can be performed according to a conventional method, and a mixer such as a Henschel mixer can be used.

[0098] The amount of the external additive used is preferably 0.05 part by mass or more, more preferably 0.1 part by mass or more, and still more preferably 0.3 part by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, with respect to 100 parts by mass of the toner particles (classified product) before being treated with the external additive, from the viewpoints of the chargeability, fluidity, and transferability of the toner.

[0099] The volume median particle diameter (D 50 ) of the toner obtained by the present invention 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 the present specification, the volume median particle diameter (D 50 ) means the particle diameter at which the cumulative volume frequency calculated by the volume fraction becomes 50% when calculated from the smaller particle diameter side. Further, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before being treated with the external additive is defined as the volume median particle diameter of the toner.

[0100] The toner obtained by the method of the present invention can be used as a one-component developer toner or as a two-component developer by mixing with a carrier.

Examples

[0101] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The physical properties of the resin and the like were measured by the following methods.

[0102] 〔Softening point of resin〕 Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a heating rate of 6 °C / min, a load of 1.96 MPa is applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. Plot the plunger descent amount of the flow tester against the temperature, and take the temperature at which half of the sample has flowed out as the softening point.

[0103] 〔Maximum peak temperature of resin endotherm〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), weigh 0.01 - 0.02 g of the sample into an aluminum pan, cool it from room temperature (25 °C) to 0 °C at a cooling rate of 10 °C / min, and maintain it at 0 °C for 1 minute. Then, measure it at a heating rate of 10 °C / min. Among the observed endothermic peaks, take the temperature of the peak with the largest peak area as the maximum peak temperature of the endotherm. For crystalline resins, take the maximum peak temperature of the endotherm as the melting point.

[0104] 〔Glass transition temperature of resin〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), weigh 0.01 - 0.02 g of the sample into an aluminum pan, heat it up to 200 °C, and then cool it from that temperature to 0 °C at a cooling rate of 10 °C / min. Next, heat the sample up to 150 °C at a heating rate of 10 °C / min and measure the endothermic peak. Take the temperature at the intersection of the extension of the baseline below the maximum peak temperature of the endotherm and the tangent showing the maximum slope from the rising part of the peak to the peak apex as the glass transition temperature.

[0105] 〔Melting point of release agent〕 Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), weigh 0.01 - 0.02 g of the sample into an aluminum pan, heat it up to 200 °C at a heating rate of 10 °C / min, and then cool it from 200 °C to -10 °C at a cooling rate of 5 °C / min. Then, heat the sample up at a heating rate of 10 °C / min and measure the heat quantity, and take the maximum peak temperature of the endotherm as the melting point.

[0106] 〔Average particle diameter of inorganic fine particles and external additives used for micronization〕 The average particle diameter refers to the number average particle diameter. The particle diameters (average value of the major axis and minor axis) of 500 particles are measured from a scanning electron microscope (SEM) photograph, and the number average value thereof is used.

[0107] 〔Volume median diameter (D 50 ) of toner〕 · Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) · Aperture diameter: 100 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 liquid: Prepared by dissolving polyoxyethylene lauryl ether "Emulgen (registered trademark) 109P" [manufactured by Kao Corporation, HLB (Griffin) = 13.6] in the electrolyte to adjust to 5% by mass. · Dispersion conditions: Add 10 mg of the measurement sample to 5 mL of the dispersion liquid, disperse it for 1 minute with an ultrasonic disperser (machine name: US-1 manufactured by SND Co., Ltd., output: 80 W), then add 25 mL of the electrolyte, and further disperse it for 1 minute with the ultrasonic disperser to prepare a sample dispersion liquid. · Measurement conditions: By adding the sample dispersion liquid to 100 mL of the electrolyte, adjust to a concentration at which the particle diameters of 30,000 particles can be measured in 20 seconds, then measure 30,000 particles, and determine the volume median diameter (D 50 ) from the particle size distribution.

[0108] Resin production example 1 Put the alcohol component, carboxylic acid component, and esterification catalyst shown in Table 1 into a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydrating tube, and a stainless steel stirring rod, heat to 235 °C under a nitrogen atmosphere, and react for 6 hours. Further, cool to 210 °C and react at 40 kPa until the softening point shown in Table 1 is reached to obtain an amorphous polyester resin (resin A1). The physical properties of the obtained resin are shown in Table 1.

[0109]

Table 1

[0110] Production Example 2 of Resin Into a 10 L four-necked flask equipped with a thermometer, a stainless steel stirring rod, a reflux condenser, a dropping funnel, and a nitrogen inlet tube, 2 L of xylene was placed. Into the dropping funnel, 880 g of styrene, 220 g of n-butyl acrylate, and 100 g of dibutyl peroxide as a radical polymerization initiator were placed. Under a nitrogen atmosphere, while stirring, the temperature of the xylene was raised to 135 °C, and the mixture in the dropping funnel was added dropwise over 1 hour. Then, the temperature was raised to 200 °C, held at 200 °C for 2 hours, and then the pressure in the flask was further reduced and held at 8 kPa for 1 hour to remove the xylene, obtaining a styrene acrylic resin (Resin A2). The glass transition temperature of the obtained resin was 54 °C, and the softening point was 115 °C.

[0111] Production Example 3 of Resin The alcohol component and carboxylic acid component shown in Table 2 were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a reflux condenser, and a nitrogen inlet tube, and the temperature was raised to 200 °C over 8 hours in a mantle heater under a nitrogen atmosphere. Then, an esterification catalyst was added, and the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, obtaining crystalline polyester resins (Resins C1 to C7, C9). The physical properties are shown in Table 2.

[0112] Production Example 4 of Resin The alcohol component, carboxylic acid component, and polymerization inhibitor shown in Table 2 were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a reflux condenser, and a nitrogen inlet tube, and the temperature was raised to 200 °C over 8 hours in a mantle heater under a nitrogen atmosphere. Then, an esterification catalyst was added, and the reaction was carried out at 8 kPa until the softening point shown in Table 2 was reached, obtaining a crystalline polyester resin (Resin C8). The physical properties are shown in Table 2.

[0113] Production Example 5 of Resin The alcohol component shown in Table 2, the carboxylic acid component other than trimellitic anhydride, and the esterification catalyst were placed in a 5-liter four-necked flask equipped with a nitrogen inlet tube, a water removal tube, and a stainless steel stirring rod. Under a nitrogen atmosphere, the reaction was carried out at 200°C until the reaction rate reached 90%, and then the reaction was carried out at 8 kPa for 1 hour. Thereafter, trimellitic anhydride was added, and the reaction was carried out at 200°C under normal pressure for 2 hours to obtain a crystalline polyester resin (resin C10). The physical properties are shown in Table 2. In addition, the reaction rate in this specification refers to the value of (mol of generated reaction water amount / mol of theoretical generated water amount) × 100.

[0114]

Table 2

[0115] Examples 1 to 14 and Comparative Examples 1 to 4 100 parts by mass of the binder resin shown in Table 3, 5 parts by mass of the colorant "ECB-301" (manufactured by Dainichi Seika Co., Ltd., phthalocyanine blue (P.B.15:3)), 3 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 75°C), and 0.5 parts by mass of the charge control agent "Bontron E-304" (manufactured by Orient Chemical Industries Co., Ltd.) were mixed using a Henschel mixer for 1 minute and then melt-kneaded under the conditions shown below.

[0116] The obtained raw material mixture was supplied to a continuous two-open roll type kneader "Neidex" (manufactured by Mitsui Mining Co., Ltd.) using a table feeder for kneading to obtain a kneaded product. The continuous two-open roll type kneader used at this time had a roll outer diameter of 0.14 m and an effective roll length of 0.8 m. The operating conditions were that the rotational speed of the high-speed side roll (front roll) was 75 r / min (33 m / min), the rotational speed of the low-speed side roll (rear roll) was 50 r / min (22 m / min), and the roll gap was 0.1 mm. The temperature of the heating and cooling medium inside the roll was set such that the temperature of the raw material input side of the high-speed roll was 150°C, the temperature of the kneaded product discharge side was 100°C, the temperature of the raw material input side of the low-speed roll was 75°C, and the temperature of the kneaded product discharge side was 30°C, respectively. Also, the supply rate of the raw material mixture was 10 kg / h, and the average residence time was about 5 minutes.

[0117] After cooling the obtained kneaded product to about 25°C, it was roughly pulverized using a pulverizer "Rotoplex" (manufactured by Hosokawa Micron Corporation), and a roughly pulverized product with a maximum diameter of 2 mm or less was obtained by passing it through a sieve with a mesh opening of 2 mm. 100 parts by mass of the obtained roughly pulverized product and the inorganic fine particles shown in Table 3 were mixed for 2 minutes using a Henschel mixer to obtain a roughly pulverized product with inorganic fine particles attached thereto.

[0118] This roughly pulverized product with inorganic fine particles attached thereto was finely pulverized and classified by upper limit (removal of coarse powder) using a counter jet mill "400AFG" (manufactured by Hosokawa Alpine). Further, lower limit classification (removal of fine powder) was performed using a classifier "TTSP" (manufactured by Hosokawa Alpine), and toner particles with a volume median diameter (D 50 ) of 6.5 μm were obtained.

[0119] 100 parts by mass of the obtained toner particles, 1.0 part by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: DMDS, average particle diameter: 16 nm), and 1.0 part by mass of hydrophobic silica "RY-50" (manufactured by Nippon Aerosil Co., Ltd., hydrophobizing agent: silicone oil, average particle diameter: 40 nm) as external additives were mixed for 3 minutes at 3000 r / min (circumferential speed 32 m / sec) using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to obtain toner.

[0120] Comparative Example 5 In the melt kneading step, instead of the continuous two-open roll type kneader, a co-rotating twin-screw extruder "PCM-30" (manufactured by Ikegai Corporation, shaft diameter 2.9 cm, shaft cross-sectional area 7.06 cm 2 ) was used, and toner was obtained in the same manner as in Example 1. The operating conditions of the twin-screw extruder were a barrel set temperature of 100°C, a shaft rotation speed of 200 r / min (circumferential speed of shaft rotation 0.30 m / sec), and a mixture supply rate of 10 kg / h (mixture supply amount per unit cross-sectional area of shaft 1.42 kg / h·cm 2 ).

[0121] Comparative Example 6 In Example 1, toner was obtained in the same manner as in Example 1, except that the coarsely pulverized material was not mixed with inorganic fine particles and was directly subjected to fine pulverization, upper limit classification (removal of coarse powder), and lower limit classification (removal of fine powder).

[0122] Test Example 1 [Glossiness of Printed Surface] The toner was mounted in a non-magnetic one-component developing device "OKI MICROLINE 5400" (manufactured by OKI Electric Industry Co., Ltd.), and the toner adhesion amount was adjusted to 0.40 ± 0.03 mg / cm 2 and a solid image of 4.1 cm × 4.1 cm was printed on "J paper" (manufactured by Fujifilm Business Innovation Co., Ltd.). The solid image was taken out before passing through the fixing machine to obtain an unfixed image. The paper with the obtained unfixed image was loaded into a non-magnetic one-component developing device "OKI MICROLINE 5400" (manufactured by OKI Electric Industry Co., Ltd.), and a solid image of 4.1 cm × 4.1 cm was printed again. The solid image was taken out before passing through the fixing machine to obtain an unfixed image (two layers) of 0.80 ± 0.06 mg / cm 2 The same operation was repeated to obtain an unfixed image (three layers) of 1.20 ± 0.09 mg / cm 2

[0123] The obtained unfixed image consisting of three layers was fixed using an external fixing machine in which the fixing roll of "OKI MICROLINE 3010" (manufactured by OKI Electric Industry Co., Ltd.) was taken out externally. The temperature of the fixing roll was set to 100°C and fixed at a fixing speed of 80 mm / sec. Then, the temperature of the fixing roll was set to 105°C and the same operation was performed. This was done while increasing the temperature by 5°C up to 190°C. The glossiness of the obtained fixed image consisting of three layers at each fixing temperature was measured, and the maximum value was evaluated as the glossiness (gloss). The glossiness was measured using a gloss meter "PG-1" (manufactured by Nippon Denshoku Industries Co., Ltd.) with the light source set at 60°. A higher glossiness indicates better glossiness. The results are shown in Table 3.

[0124] Test Example 2 [Resistance to Document Offset during Storage at High Temperature] Toner was installed in a non-magnetic single-component developing device "OKI MICROLINE 5400" (manufactured by Oki Electric Industry Co., Ltd.), and 8,000 sheets were printed at a printing rate of 1% under the conditions of a temperature of 25 °C and a relative humidity of 50%. Next, the toner adhesion amount was adjusted to 0.40 ± 0.03 mg / cm 2 and a solid image of 4.1 cm × 4.1 cm was printed. The solid image was taken out before passing through the fixing machine to obtain an unfixed image. The obtained unfixed image was fixed with an external fixing machine in which the fixing roll temperature of "OKI MICROLINE 3010" (manufactured by Oki Electric Industry Co., Ltd.) was taken out externally at a fixing speed of 80 mm / sec with the temperature of the fixing roll set at 150 °C. Note that J paper (manufactured by Fujifilm Business Innovation Corporation) was used as the printing medium.

[0125] The obtained fixed image was overlaid on J paper on which no printing had been performed, and a load of 80 g / cm 2 was applied to the sample in which two sheets of paper were overlaid, and it was left standing for 1 day in an environment at a temperature of 50 °C. Then, the overlaid papers were taken out, the ends of the papers were lifted little by little to create a gap with the lower paper, and a finger was inserted there to peel them off. Ten samples were prepared, and the state of the fixed image part after peeling was visually confirmed, and the resistance to document offset was evaluated according to the following evaluation criteria. The results are shown in Table 3.

[0126] 〔Evaluation Criteria〕 A: At the time of peeling, there is no peeling sound in all 10 samples, and no image defects are observed. B: At the time of peeling, there is a peeling sound in 1 or 2 samples out of 10, but no image defects are observed. C: At the time of peeling, there is a peeling sound in 1 or 2 samples out of 10, and image defects are observed, or there is a peeling sound in 3 or more samples, but no image defects are observed. D: At the time of peeling, there is a peeling sound in 3 or more samples out of 10, and image defects are observed.

[0127]

Table 3

[0128] From the above results, it can be seen that in Examples 1 to 14, toners excellent in both the glossiness of the printed surface and the resistance to document offset during storage at high temperatures can be obtained. On the other hand, in Comparative Example 1 where a crystalline polyester resin is not used, the toner is difficult to deform during heat fixing and has low smoothness, so it lacks glossiness. In Comparative Example 2 where the amount of the crystalline polyester resin used is too large, although the glossiness is high, the dispersibility of the crystalline polyester resin is poor and the adhesion of the inorganic fine particles used during pulverization is uneven, so it lacks resistance to document offset. In Comparative Example 3 where a short-chain monomer is not used in the crystalline polyester resin, the compatibility between the crystalline polyester resin and the amorphous resin is low and the dispersibility of the crystalline polyester resin is poor, so the adhesion of the inorganic fine particles used during pulverization is uneven and the decrease in resistance to document offset is remarkable. In Comparative Example 4 where the main component of the carboxylic acid component of the crystalline polyester resin is an aromatic dicarboxylic acid-based compound, the melting point of the crystalline polyester resin is high and the viscosity is also high, so it is difficult to deform during heat fixing and lacks glossiness. In Comparative Example 5 where a twin-screw extruder is used for melt kneading, since the kneading strength of the kneader is low, the dispersibility of the crystalline polyester resin is insufficient and it lacks resistance to document offset. In Comparative Example 6 where inorganic fine particles are not used in the pulverization step, since the strength of the toner surface layer is insufficient, it lacks resistance to document offset.

Industrial Applicability

[0129] The electrostatic charge image developing toner obtained by the method of the present invention is suitably used for developing a latent image formed in an electrostatic charge image developing method, an electrostatic recording method, an electrophotographic printing method, etc.

Claims

1. Step 1 of melt-kneading at least an amorphous resin and a crystalline polyester resin using an open roll kneader; Step 2 of mixing the obtained pulverized product with inorganic fine particles after pulverizing the kneaded product obtained in Step 1; and Step 3 of pulverizing and classifying the mixture obtained in Step 2. A method for producing a toner for electrostatic charge image development, wherein the crystalline polyester resin is a polycondensate of an alcohol component containing 80 mol% or more of an aliphatic diol and a carboxylic acid component containing 80 mol% or more of an aliphatic dicarboxylic acid-based compound, the alcohol component contains a short-chain aliphatic diol having 2 to 6 carbon atoms and / or the carboxylic acid component contains a short-chain aliphatic dicarboxylic acid-based compound having 4 to 8 carbon atoms, and the mass ratio of the crystalline polyester resin to the amorphous resin is 2 / 98 or more and 18 / 82 or less. A method for producing a toner for electrostatic charge image development.

2. The method for producing a toner for electrostatic charge image development according to Claim 1, wherein the amount of inorganic fine particles used in Step 2 is 0.3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the pulverized product.

3. The method for producing a toner for electrostatic charge image development according to Claim 1 or 2, wherein the melting point of the crystalline polyester resin is 60°C or higher and 100°C or lower.

4. The method for producing a toner for electrostatic charge image development according to any one of Claims 1 to 3, wherein the amorphous resin contains an amorphous polyester resin.

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