JP4439006B2 - Method for producing toner for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a toner for electrophotography superior in dispersibility of a colorant can be produced advantageously, without limiting the kind of resin binder, when a toner for electrophotography is manufactu by a wet process. <P>SOLUTION: The process for preparing a toner for electrophotography, comprising a resin binder and a colorant includes the steps of (1) mixing the resin binder and a master batch of the colorant dispersed in a resin and forming primary particles, in an aqueous medium in the presence of a nonionic surfactant; and (2) aggregating and unifying the primary particles. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

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

In recent years, it has been desired to reduce the particle size of toner in order to improve image quality. As a toner production method, there are a melt-kneading pulverization method and a wet production method such as an emulsion aggregation method. Patent Documents 1 and 2 disclose an invention using a master batch of a colorant in a wet manufacturing method. However, in the method described in Patent Document 1, the applicable binder resin is limited to those that can be dissolved in an organic solvent, and if the solubility of the binder resin in the organic solvent is small, the yield is extremely reduced. . In addition, the solvent suspension method described in Patent Document 2 is not limited to a resin in which the binder resin can be dissolved in an organic solvent, and the particle size of the toner is limited because the droplet size that can be prepared by the suspension method is limited. There are limits to control and particle size distribution control.
JP 2002-296839 A (Claims 1 and 2) JP-A-7-333890 (Claims 1 and 2)

  An object of the present invention is to economically produce an electrophotographic toner excellent in colorant dispersibility without limiting the type of binder resin when the electrophotographic toner is produced by a wet process. It is to provide a method.

  The present invention relates to a method for producing an electrophotographic toner comprising a binder resin and a colorant, wherein the binder resin and a colorant masterbatch in which the colorant is dispersed in the resin are mixed and nonionic The present invention relates to a method for producing an electrophotographic toner, which comprises a step (1) of producing primary particles in an aqueous medium in the presence of a surfactant, and a step (2) of aggregating and coalescing the primary particles.

  According to the present invention, when an electrophotographic toner is manufactured by a wet manufacturing method, an electrophotographic toner excellent in colorant dispersibility can be economically manufactured without limiting the type of binder resin. Further, the production method of the present invention can be produced without using an organic solvent, and is therefore a useful method from the viewpoint of environment and energy saving.

  The electrophotographic toner obtained by the present invention contains at least a binder resin and a colorant.

  Examples of the binder resin in the present invention include known resins used for toners, such as polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and the like. Among them, polyester and styrene-acrylic copolymer are used. Preferably, polyester is more preferable from the viewpoints of colorant dispersibility, fixability, and durability. The polyester content is preferably 60% by weight or more, more preferably 70% by weight or more, and still more preferably 80% by weight or more in the binder resin.

  The polyester may be either a crystalline polyester or an amorphous polyester, but more preferably contains a crystalline polyester from the viewpoint of low-temperature fixability.

  The degree of crystallization of polyester is represented by the ratio between the softening point and the highest endothermic peak temperature measured by a differential scanning calorimeter, the crystallinity index defined by the softening point / the highest endothermic peak temperature, and this value is generally 1.5. If it exceeds, the resin is amorphous, and if it is less than 0.6, the crystallinity is low and there are many amorphous portions. The degree of crystallization can be adjusted by the type and ratio of raw material monomers, production conditions (for example, reaction temperature, reaction time, cooling rate) and the like. The highest endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. If the maximum peak temperature is within 20 ° C. from the softening point, the melting point is set, and the peak having a difference from the softening point exceeding 20 ° C. is a peak due to glass transition.

  The crystalline polyester in the present invention refers to those having a crystallinity index of 0.6 to 1.5. The crystallinity index of the crystalline polyester is preferably 0.8 to 1.3, more preferably 0.9 to 1.1, and still more preferably 0.98 to 1.05, from the viewpoint of low-temperature fixability.

  As a raw material monomer for polyester, a known divalent or higher valent alcohol component and a known carboxylic acid component such as a divalent or higher carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.

  Examples of the alcohol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, Aliphatic diols such as 1,8-octanediol, neopentyl glycol, 1,4-butenediol; formula (I):

(Wherein R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16, preferably 1.5 to 5.0). Examples include aromatic diols such as alkylene oxide adducts; trihydric or higher polyhydric alcohols such as glycerin and pentaerythritol.

  Examples of carboxylic acid components include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, etc. Aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid; Aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid; Trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; And anhydrides of these acids, alkyl (C1-3) esters, and the like. The acids, acid anhydrides, and alkyl esters of the acids as described above are collectively referred to herein as carboxylic acid compounds.

  Furthermore, the alcohol component and the carboxylic acid component may appropriately contain a monovalent alcohol or a monovalent carboxylic acid compound from the viewpoint of adjusting the molecular weight.

  From the viewpoint of promoting the crystallinity of the polyester, the alcohol component of the crystalline polyester preferably contains an aliphatic diol having 2 to 8 carbon atoms, and among them, α, ω-linear alkanediol, 1,4-butanediol, 1,6-hexanediol, and 1,8-octanediol are preferred.

  The content of the aliphatic diol having 2 to 8 carbon atoms in the total alcohol component is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, from the viewpoint of promoting the crystallinity of the polyester. Among them, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, or a mixture thereof is preferably 80 to 100 mol%, more preferably 90 to 100 mol in the total alcohol components. % Content is desirable.

  The carboxylic acid component of the crystalline polyester includes an aliphatic dicarboxylic acid compound having 2 to 6 carbon atoms such as oxalic acid, malonic acid, maleic acid, fumaric acid, succinic acid, and adipic acid from the viewpoint of promoting the crystallinity of the polyester. Is preferably contained. The proportion of these aliphatic dicarboxylic acid compounds having 2 to 6 carbon atoms in the total carboxylic acid component is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, from the viewpoint of promoting the crystallinity of the polyester. is there. Among them, fumaric acid and / or succinic acid is preferably contained in an amount of 80 to 100 mol%, more preferably 90 to 100 mol%.

  Further, from the viewpoint of chargeability and durability of the toner, the carboxylic acid component of the crystalline polyester includes aromatic dicarboxylic acid compounds having an aromatic ring such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and cyclohexanedicarboxylic acid. It is preferable that an alicyclic dicarboxylic acid compound such as an acid is contained. The content of these aromatic dicarboxylic acid compounds and alicyclic dicarboxylic acid compounds in the total carboxylic acid components is preferably 80 to 100 mol%, and preferably 90 to 100 mol%, from the viewpoint of the charging property and durability of the toner. More preferred. Among these, terephthalic acid is preferably contained in the total carboxylic acid component, preferably 80 to 100 mol%, more preferably 90 to 100 mol%.

  That is, in order to promote the crystallinity of the polyester, the crystalline polyester is a polycondensation of an alcohol component containing 80 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms and a carboxylic acid component which is a carboxylic acid compound. It is preferably obtained by condensation polymerization of an alcohol component containing 90 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms and a carboxylic acid component which is a carboxylic acid compound. More preferably.

  In order to further promote the crystallinity of the polyester, the crystalline polyester comprises an alcohol component containing 80 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms and an aliphatic dicarboxylic acid compound having 2 to 6 carbon atoms. Is preferably obtained by polycondensation with a carboxylic acid component containing 80 to 100 mol% of an alcohol component containing 90 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms and 2 to 2 carbon atoms. More preferably, it is obtained by polycondensation with a carboxylic acid component containing 90 to 100 mol% of 6 aliphatic dicarboxylic acid compound.

  On the other hand, from the viewpoint of chargeability and durability of the toner, the crystalline polyester contains an alcohol component containing 80 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms, an aromatic dicarboxylic acid compound and / or an alicyclic type. It is preferably obtained by polycondensation with a carboxylic acid component containing 80 to 100 mol% of a dicarboxylic acid compound, and an alcohol component containing 90 to 100 mol% of an aliphatic diol having 2 to 8 carbon atoms and an aromatic More preferably, it is obtained by polycondensation of a carboxylic acid component containing 90 to 100 mol% of an aliphatic dicarboxylic acid compound and / or an alicyclic dicarboxylic acid compound.

  The crystalline polyester in the present invention preferably has an acid group at the end of the molecular chain. Examples of the acid group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid. A carboxyl group is preferable from the viewpoint of achieving both the emulsifiability of the resin and the environmental resistance characteristics of the toner using the resin. The number of acid groups at the molecular chain ends of the crystalline polyester is one important factor that determines the stability of the emulsified particles and the particle size distribution and particle size of the toner. In order to stabilize the emulsified particles and obtain a toner having a small particle size with a sharp particle size distribution, the number of acid groups at the molecular chain terminals is preferably 0.015 to 0.9 mmol, and 0.08 to 0.85, per gram of crystalline polyester. mmol is more preferable, 0.15-0.8 mmol is more preferable, and 0.25-0.75 mmol is more preferable.

  If necessary, a carboxyl group can be introduced into the molecular main chain of the polyester using a polyvalent acid such as trimellitic acid as the carboxylic acid component and a polyhydric alcohol such as pentaerythritol as the alcohol component. The number of acid groups in the molecular main chain of the polyester is preferably 5 mol% or less, more preferably 3 mol% or less, with respect to the total number of moles of the carboxylic acid component constituting the polyester, from the viewpoint of crystallization inhibition. More preferably, it is 1 mol% or less.

  Further, in the crystalline polyester, the molar ratio represented by the acid group in the molecular main chain / the acid group at the end of the molecular chain is preferably 30 mol% or less, more preferably 20 mol% or less, from the same viewpoint. The mol% or less is more preferable, the 5 mol% or less is more preferable, and the 2 mol% or less is more preferable.

  The amount of the acid group in the molecular main chain of the crystalline polyester and the acid group at the end of the molecular chain are determined based on the structure and preparation ratio of the raw material acid and raw material alcohol of the crystalline polyester, the number average molecular weight of the crystalline polyester, and the acid value. Can be calculated from In addition, analytical methods such as nuclear magnetic resonance spectroscopy (NMR) and photoelectron spectroscopy (XPS, ESCA, etc.) can be obtained in combination with acid value measurement.

  The content of the crystalline polyester in the binder resin is preferably 60% by weight or more, more preferably 70% by weight or more, and further preferably 80% by weight or more from the viewpoint of low-temperature fixability. Further, the content of the crystalline polyester in the toner is preferably 60% by weight or more, more preferably 70% by weight or more, and further preferably 80 to 95% by weight.

  On the other hand, the alcohol component of amorphous polyester includes polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) It contains an alkylene oxide adduct of bisphenol A represented by the formula (I) such as an alkylene (2 to 3) oxide (average number of added moles of 1 to 16) oxide of bisphenol A such as propane. Is preferred.

  The content of the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 5 mol% or more, more preferably 50 mol% or more, further preferably 80 mol% or more, and 100 mol% in the alcohol component. Is particularly preferred.

  The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst.

  The amorphous polyester preferably has a softening point of 95 to 160 ° C., a glass transition point of 50 to 75 ° C., an acid value of 1 to 40 mgKOH / g, and a hydroxyl value of 3 to 60 mgKOH / g. The melting point of the crystalline polyester is preferably 60 to 150 ° C., more preferably 60 to 130 ° C., and still more preferably 60 to 120 ° C. from the viewpoint of low-temperature fixability.

  The number average molecular weight of the amorphous polyester is preferably 1000 to 100000, more preferably 1000 to 50000, and still more preferably 1000 to 12000 from the viewpoint of durability and fixability.

  The number average molecular weight of the crystalline polyester is preferably 2000 to 100,000, more preferably 2000 to 20000, still more preferably 2000 to 10,000, and still more preferably 2000 to 8000, from the viewpoints of emulsifying properties, fixing properties, and offset resistance.

  There is no restriction | limiting in particular as a coloring agent, A well-known coloring agent is mentioned, According to the objective, it can select suitably. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, Brilliantamine 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Various pigments, acridine, xanthene, azo, benzoquinone, azine, anthraquinone, indico, thioindico, Roshianin system, aniline black, polymethine, triphenylmethane dyes, diphenylmethane dyes, thiazine, thiazole, including but various dyes xanthene, etc., from the viewpoint of fading resistance, pigments are preferred.

  The average particle diameter of the colorant is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more from the viewpoint of coloring power and color reproduction region. On the other hand, the average particle size of the colorant is preferably smaller than the average particle size of the primary particles in order to be included in the primary particles composed of the binder resin and the master batch of the colorant. Therefore, 100 nm or less is preferable, 80 nm or less is more preferable, and 65 nm or less is more preferable. From these viewpoints, the average particle size of the colorant is preferably 5 to 100 nm, more preferably 10 to 80 nm, and further preferably 20 to 65 nm. The average particle diameter of the colorant can be determined from, for example, a photographic image of a water dispersion at the time of preparation of the colorant by a transmission electron microscope (TEM), and is a number calculated from a plurality of at least 200 colorant particles. Refers to the average particle size.

  The blending amount of the colorant is preferably 3 to 25 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  Further, the toner obtained according to the present invention may appropriately include additives such as a release agent, a charge control agent, a conductivity adjusting agent, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, and an anti-aging agent. It may be added.

  As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide; carnauba wax, rice wax, candelilla Plant waxes such as wax, tree wax and jojoba oil; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin lux, microcrystalline wax, and Fischer-Tropsch wax. These release agents may be used alone or in combination of two or more.

  Examples of the charge control agent include chromium azo dyes, iron azo dyes, aluminum azo dyes, and salicylic acid metal complexes.

  In the toner production method of the present invention, a binder resin and a colorant master batch in which a colorant is dispersed in the resin are mixed, and primary particles are generated in an aqueous medium in the presence of a nonionic surfactant. It is characterized by the process (process (1)).

  In the toner production method of the present invention, there is no limitation on the method of mixing the binder resin and the colorant master batch, and they may be mixed simultaneously with the nonionic surfactant. Moreover, it is preferable to prepare primary particles containing the binder resin and the colorant in the aqueous medium after at least the step of melt-kneading the binder resin and the master batch of the colorant. For melt kneading, it is preferable to use an open roll type biaxial kneader. The open roll type twin-screw kneader is a kneader in which two rolls are arranged close to each other in parallel, and a heating function or a cooling function can be imparted by passing a heat medium through each roll. Therefore, the open roll type twin screw kneader is an open type part to be melt kneaded and is provided with a heating roll and a cooling roll. The heat of kneading generated can be easily dissipated.

  Furthermore, the toner having excellent colorant dispersibility by adjusting the temperature so that the temperature of the kneaded material is preferably in the range of Ts-20 ° C to Ts + 20 ° C, more preferably Ts-15 ° C to Ts + 15 ° C. Can be manufactured more easily. Here, when the binder resin is composed of two or more kinds of resins, the softening point of the mixed resin is used as Ts. Further, the temperature of the kneaded product refers to the temperature of the kneaded product itself attached to the roll.

  The gap between the two rolls is preferably 0.1 to 10 mm, more preferably 0.1 to 3 mm. Moreover, there is no limitation in particular about the structure of each roll, a magnitude | size, material, etc., The roll surface may be smooth and may be a wave type, an uneven | corrugated type, etc.

  Moreover, it is preferable that the rotation speed of a roll is 2-100 m / min of peripheral speeds. Further, the rotation speed ratio of the two rolls is preferably 1/10 to 9/10 (cooling roll / heating roll).

  In the present invention, by mixing the binder resin and the nonionic surfactant, the viscosity of the mixture can be reduced and the binder resin can be atomized. It has been found that the decrease is due to the fact that the nonionic surfactant is compatible with the binder resin, and surprisingly the softening point of the resin is apparently decreased. Using this phenomenon, if the apparent softening point of the binder resin compatible with the nonionic surfactant can be lowered below the boiling point of water, the resin alone has a melting point or softening point of 100 ° C. or higher. Even with the binder resin, a dispersion liquid in which the binder resin is dispersed in water can be obtained by dropping water at normal pressure. Since at least water and a nonionic surfactant are sufficient, it can be applied to resins that are insoluble in organic solvents, as well as facilities for recovering organic solvents and maintaining the working environment as used in Patent Document 1 There is also an advantage that a resin dispersion liquid can be produced economically without a burden. Therefore, the aqueous medium used in the present invention may contain a solvent such as an organic solvent, but preferably contains 95% by weight or more, more preferably 99% by weight or more of water. Even when only water is used without substantially using an organic solvent, the binder resin can be atomized.

  Nonionic surfactants include, for example, polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl allyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyoxyethylene sorbitan mono Polyoxyethylene sorbitan esters such as laurate, polyoxyethylene sorbitan monostearate, polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, oxyethylene / Oxypropylene block copolymer and the like. Further, an anionic surfactant or a cationic surfactant may be used in combination with the nonionic surfactant as long as the effects of the present invention are not impaired.

  In selecting a nonionic surfactant, it is important to select a nonionic surfactant having good compatibility with the resin. In order to obtain a stable binder resin dispersion, the HLB of the nonionic surfactant is preferably 12 to 18, and depending on the type of the binder resin, two or more different HLB nonionic interfaces may be used. More preferably, an activator is used. For example, in the case of a highly hydrophilic resin, it is sufficient to use at least one kind of nonionic surfactant having an HLB of 12 to 18. However, in the case of a highly hydrophobic resin, a low HLB, for example, an HLB of 7 It is preferable to adjust the weighted average of both HLBs to 12-18 by using about ~ 10 and those having high HLB, for example, 14-20 HLB. In this case, it is presumed that those having an HLB of about 7 to 10 are compatibilizing the resin, and those having a high HLB are stabilizing the dispersion of the resin in water.

  The nonionic surfactant is preferably adsorbed on the colorant and dispersed in the binder resin. By adjusting the HLB of the nonionic surfactant to the above range, the nonionic surfactant is easily adsorbed on the colorant surface, and at the same time, the colorant is present as a colloidal dispersion in an aqueous medium. It is preferable because it stably exists in the binder resin.

  The clouding point of the nonionic surfactant is preferably 70 to 105 ° C., more preferably 80 to 105 ° C. when the binder resin is atomized under normal pressure and water.

  From the viewpoint of lowering the melting point of the binder resin, the amount of the nonionic surfactant used is preferably 5 parts by weight or more with respect to 100 parts by weight of the binder resin, and controls the nonionic surfactant remaining in the toner. From this viewpoint, the amount is preferably 80 parts by weight or less. Therefore, from the viewpoint of making these compatible, the amount of the nonionic surfactant used is preferably 5 to 80 parts by weight, more preferably 10 to 70 parts by weight, and more preferably 20 to 60 parts by weight with respect to 100 parts by weight of the binder resin. Part by weight is more preferred.

  Furthermore, the present invention is also characterized in that a colorant master batch in which a colorant is dispersed in a resin is used.

  The resin used for the master batch of the colorant may be the same type of resin as the binder resin or a different type of resin, but the same type of resin is preferable from the viewpoint of dispersibility of the colorant.

  In addition, the acid value of the binder resin mixed with the master batch is preferably equal to or more than the acid value of the resin used for the master batch of the colorant from the viewpoint of dispersibility of the colorant in the binder resin. Is 2 mgKOH / g or more, more preferably 5 mgKOH / g or more.

As a method for producing a master batch of a colorant, for example,
Method (1): A dry powdery colorant and resin, and if necessary, a dispersion aid such as water are charged into a mixer or kneader, mixed to wet the colorant and resin, and under pressure or normal pressure A method in which the colorant and the resin are melt-kneaded by heating with, and then the moisture is evaporated under normal pressure or reduced pressure to be removed by drying,
Method (2): The dried colorant and resin are heated to melt the resin, then water is added and the colorant and the resin are melt-kneaded under pressure or normal pressure, and the moisture is reduced to normal pressure or reduced pressure. Evaporating under and removing to dry,
Method (3): A method of removing moisture by melting and kneading a press cake of a colorant (including an aqueous paste) and a resin to transfer the colorant of the aqueous phase to the resin phase. Then, from the viewpoint of dispersibility of the colorant, the method (3) is preferable, and the master batch obtained by the method (3) is generally called a flushing master batch. In the production of the flushing masterbatch, the colorant in the aqueous phase is transferred to the resin phase by kneading the press cake and the resin. Then, the resin is softened in a bowl shape by the strong shearing action of the kneader during flushing, and the colorant is transferred and dispersed in the resin by the action of the internal shearing force of the resin softened in the bowl shape. For this reason, the flushing masterbatch has significantly better dispersibility of the colorant compared to the method using the colorant once dried as in the method (1) or method (2).

  The colorant obtained by synthesis is generally a micron order crystal and is called a colorant crude. The colorant press cake used in the production of the flushing masterbatch may be a colorant crude presscake, but it is a fine colorant presscake obtained by refining the colorant crude by physical techniques or chemical treatment. Preferably there is.

  The press cake of the colorant refers to a product obtained by dehydrating an aqueous dispersion of the colorant as appropriate by filtration or the like. The solid content (colorant) amount in the press cake of the colorant is preferably 30 to 70% by weight, and from the viewpoint of dispersibility of the colorant in the resin, the press cake becomes 40 to 60% by weight in the form of an aqueous paste. Is more preferable.

  One physical method for miniaturizing the colorant crude is a mechanical friction method. The method by mechanical grinding is not particularly limited, but, for example, a grinding medium such as a metal ball or a ceramic ball or the like for milling is introduced into the crusher, and the grinding action is manifested by vibration of the crusher. Or a method of causing the grinding action by vibration and rotation by further rotating the crusher itself like a drum. At the time of grinding, the grinding effect can be enhanced by using grinding aids such as salt and salt cake as grinding aids. Therefore, the colorant used as a raw material of the flushing masterbatch in the present invention is ground by a method called salt milling using a salt such as salt as a grinding aid from the viewpoint of reducing the particle size of the colorant. A colorant presscake is preferred. The dried colorant crude is usually dried under reduced pressure by heating with a heating source (circulation of a heating medium such as water vapor) installed in a dryer. Drying can be performed batchwise, continuously, or the like. Examples of the dryer that can be used in the above method include commercially available products called vibration fluidized dryers, vibration mills equipped with heating devices and decompression devices, and the like. By the method of grinding in a dryer and drying, the reaction mixture containing the colorant and reaction solvent obtained through the synthesis step is directly ground and dried without going through the pigmentation step, thereby reducing the colorant. Can also be manufactured.

  The resin used in the flushing masterbatch is preferably a resin having a softening point of preferably 130 ° C. or lower, more preferably 120 ° C. or lower, and the temperature when kneading the resin with the colorant press cake is softened by the resin. The temperature is preferably below the point and below the boiling point of water.

  Further, in the production of the flushing masterbatch, when kneading the colorant press cake and the resin, an organic solvent can be used as necessary. However, the flushing masterbatch used in the present invention is an organic solvent. It is preferable that is not substantially used.

  In step (1), when primary particles are generated in an aqueous medium in the presence of a nonionic surfactant, the temperature in the system prevents a decrease in the dispersibility and dispersion efficiency of the nonionic surfactant. From the viewpoint, it is desirable to keep the nonionic surfactant within the temperature range of 10 ° C., preferably 8 ° C., more preferably 5 ° C. above and below the cloud point.

  In the step (1), for example, a mixture of a binder resin, a master batch of a colorant, and a nonionic surfactant is stirred and uniformly mixed in the system, and an aqueous medium (preferably deionized water or , Distilled water) is preferably added dropwise. At this time, it is preferable to pay attention so that the binder resin containing a colorant compatible with the nonionic surfactant does not separate from water.

  The mixing amount of the aqueous medium is preferably 100 to 3000 parts by weight, more preferably 400 to 3000 parts by weight, more preferably 800 to 3000 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of obtaining uniform aggregated particles in the subsequent steps. Is more preferable.

  The particle size of the primary particles can be controlled by the amount of the nonionic surfactant, the stirring force, and the addition rate of water. In the step (1), the speed at which the aqueous medium is added to the mixture containing at least the binder resin, the master batch of the colorant and the nonionic surfactant is 0.1% per 100 g of the mixture from the viewpoint of obtaining uniform primary particles. -50 g / min is preferable, 0.5-40 g / min is more preferable, and 1-30 g / min is more preferable.

  In addition, when the binder resin has an acidic group such as a carboxyl group or a sulfone group, water may be added after neutralizing all or part of the binder resin or while neutralizing the binder resin. When the binder resin having an acidic group is used, the self-emulsifying factor of the resin is a factor controlling the particle size of the primary particles in addition to the factor of the nonionic surfactant.

  A dispersant can be used as necessary for the purpose of lowering the melt viscosity and melting point of the binder resin and improving the dispersibility of the primary particles produced. Examples of the dispersant include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate; sodium dodecylbenzenesulfonate, sodium octadecylsulfate, sodium oleate, Anionic surfactants such as sodium laurate and potassium stearate; Cationic surfactants such as laurylamine acetate, stearylamine acetate and lauryltrimethylammonium chloride; Amphoteric surfactants such as lauryldimethylamine oxide; Tricalcium phosphate, Water Examples thereof include inorganic salts such as aluminum oxide, calcium sulfate, calcium carbonate, and barium carbonate. The blending amount of the dispersant is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 10 parts by weight or less with respect to 100 parts by weight of the binder resin from the viewpoint of emulsion stability and detergency.

  The solid concentration in the system for preparing the dispersion of primary particles is preferably 7 to 50% by weight, more preferably 7 to 40% by weight, from the viewpoint of the stability of the dispersion and the handling of the dispersion in the aggregation process. %, More preferably 10 to 30% by weight. The solid content includes non-volatile components such as a resin and a nonionic surfactant.

The average particle size of the primary particles is preferably larger than the average particle size of the colorant from the viewpoint of uniformly agglomerating in subsequent steps, specifically 0.05 to 3 μm is preferable, 0.05 to 1 μm is more preferable, and 0.05 to 0.8 μm is more preferable. The average particle size of the primary particles refers to the volume median particle size (D ₅₀ ) and can be measured by a laser diffraction type particle size measuring machine or the like.

  Subsequently, the primary particles obtained in the step (1) are subjected to a step of aggregation and coalescence (step (2)).

  In the step (2), the solid concentration in the system in the aggregation step for aggregating the primary particles can be adjusted by adding water to the binder resin dispersion as necessary, thereby causing uniform aggregation. Therefore, 5 to 50% by weight is preferable, 5 to 30% by weight is more preferable, and 5 to 20% by weight is further preferable.

  Further, the pH in the system in the aggregation step is preferably 2 to 10, more preferably 2 to 8, from the viewpoint of achieving both the dispersion stability of the mixed solution and the aggregation properties of fine particles such as a binder resin and a colorant. 3 to 7 are more preferable.

  From the same viewpoint, the temperature in the system in the aggregation step is preferably a softening point of the binder resin of −50 ° C. or higher and a softening point of −10 ° C. or lower, more preferably a softening point of −30 ° C. or higher and a softening point of −10 ° C. or lower. .

  When the primary particles are aggregated, not only the primary particles obtained in the step (1) are aggregated (homo-aggregation), but the same as in the step (1) except that a separate colorant master batch is not used. The dispersion of resin fine particles obtained as described above may be mixed with a dispersion of primary particles to aggregate the primary particles and other resin fine particles (heteroaggregation).

  In the aggregation process, an aggregating agent can be added in order to effectively perform aggregation. As the aggregating agent, a quaternary salt cationic surfactant, polyethyleneimine or the like is used in the organic system, and an inorganic metal salt, a divalent or higher metal complex, or the like is used in the inorganic system. Examples of inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, Examples thereof include inorganic metal salt polymers such as calcium sulfide. Among these, a trivalent aluminum salt and a polymer thereof are preferable because the addition amount is small, the aggregation ability is high, and they can be easily produced. Further, from the viewpoint of controlling charging characteristics, metal complexes and quaternary salt cationic surfactants are particularly preferred.

  The amount of the flocculant used is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less with respect to 100 parts by weight of the binder resin from the viewpoint of environmental resistance characteristics of the toner.

  The flocculant is preferably added after being dissolved in an aqueous medium, and it is preferable to sufficiently stir at the time of adding the flocculant and after the addition.

  Subsequently, the aggregated particles containing at least the binder resin and the colorant obtained in the aggregation process are heated and united.

  The heating temperature when coalescing the agglomerated particles is from the viewpoint of the target toner particle size, particle size distribution, shape control, and particle fusing property, and the softening point of the binder resin is −30 ° C. or higher, and the softening point is +10. The softening point is preferably −25 ° C. or higher, the softening point + 10 ° C. or lower is more preferable, and the softening point −20 ° C. or higher and the softening point + 10 ° C. or lower is more preferable. The stirring speed is preferably a speed at which the aggregated particles do not settle.

  A toner can be obtained by subjecting the coalesced particles obtained in the step (2) to a solid-liquid separation step such as filtration, a washing step, and a drying step as appropriate.

  In the washing step, it is preferable to use an acid in order to remove metal ions on the toner surface in order to ensure sufficient charging characteristics and reliability as the toner. Further, it is preferable to completely remove the added nonionic surfactant by washing, and washing with an aqueous solution below the cloud point of the nonionic surfactant is preferred. The washing is preferably performed a plurality of times.

  In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability.

  According to the present invention, a spherical toner having a small particle size and a narrow particle size distribution suitable for high definition and high image quality can be obtained.

From the viewpoint of high image quality and productivity, the volume median particle size (D ₅₀ ) of the toner is preferably 1 to 7 μm, more preferably 2 to 7 μm, and even more preferably 3 to 6 μm.

  Further, the softening point of the toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and further preferably 60 to 120 ° C. from the viewpoint of low-temperature fixability. Moreover, 60-140 degreeC is preferable from the same viewpoint, 60-140 degreeC is more preferable, and 60-130 degreeC is further more preferable, as for the highest peak temperature of the endotherm by a differential scanning calorimeter.

  An auxiliary agent such as a fluidizing agent may be added to the toner particle surface as an external additive to the toner obtained by the present invention. External additives include known fine particles such as silica fine particles, titanium fine particles, alumina fine particles, cerium oxide fine particles, carbon black and other inorganic fine particles, and polymer fine particles such as polycarbonate, polymethyl methacrylate and silicone resin. Can be used.

  The number average particle diameter of the external additive is preferably 4 to 200 nm, more preferably 8 to 30 nm. The number average particle diameter of the external additive is determined using a scanning electron microscope or a transmission electron microscope.

  The amount of the external additive is preferably 1 to 5 parts by weight, more preferably 1.5 to 3.5 parts by weight, based on 100 parts by weight of the toner before processing with the external additive. However, when hydrophobic silica is used as the external additive, the desired effect can be obtained by using 1 to 3 parts by weight of hydrophobic silica with respect to 100 parts by weight of the toner before processing with the external additive.

  The toner for electrophotography obtained by the present invention can be used as a non-magnetic one-component developer or a two-component developer mixed with a carrier.

1. Resin acid value
Measure according to JIS K0070.

2. Softening point of resin and toner, maximum endothermic peak temperature, melting point and glass transition point (1) Softening point Using a flow tester (Shimadzu Corporation, CFT-500D), heat 1g sample at a heating rate of 6 ℃ / min. While applying a load of 1.96 MPa with a plunger, push out from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

(2) Maximum endothermic peak temperature and melting point A sample was heated to 200 ° C using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210) and cooled to 0 ° C at a rate of 10 ° C / min. Measure at a heating rate of 10 ° C / min. Among the observed endothermic peaks, the temperature of the peak on the highest temperature side is defined as the highest endothermic peak temperature. When the maximum peak temperature is within 20 ° C. from the softening point, the peak temperature is taken as the melting point, and when it is 20 ° C. or more lower than the softening point, the peak is caused by the glass transition.

(3) Glass transition point Using a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), the sample was heated to 200 ° C and cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. Measure at ° C / min. If a peak is observed at a temperature 20 ° C or more lower than the softening point, the peak temperature is observed. If a peak is not observed at a temperature 20 ° C or higher lower than the softening point, a step is observed. The temperature at the intersection of the tangent line indicating the maximum slope of the curve and the extension line of the base line on the high temperature side of the step is read as the glass transition point. The glass transition point is a physical property peculiar to the amorphous part of the resin, and is generally observed in amorphous polyester, but is observed when amorphous part exists even in crystalline polyester. There is.

3. Crystallinity Index of Resin Using the softening point and maximum peak temperature of endotherm measured according to the above, the crystallinity index is calculated as the degree of crystallinity from the following formula.
Crystallinity index = softening point / maximum endothermic peak temperature

4). Number average molecular weight of resin By the following method, molecular weight distribution is measured by gel permeation chromatography, and a number average molecular weight is calculated.
(1) Preparation of sample solution Crystalline polyester is dissolved in chloroform and amorphous polyester is dissolved in tetrahydrofuran so that the concentration is 0.5 g / 100 ml. Next, this solution is filtered using a fluororesin filter having a pore size of 2 μm (FP-200, manufactured by Sumitomo Electric Industries, Ltd.) to remove insoluble components to obtain a sample solution.
(2) Measurement of molecular weight distribution As a solution, flow chloroform at the time of measuring crystalline polyester, and tetrahydrofuran at the time of measuring amorphous polyester at a flow rate of 1 ml / min. Stabilize. Measurement is performed by injecting 100 μl of the sample solution. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. For the calibration curve at this time, a sample prepared using several types of monodisperse polystyrene as a standard sample is used.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analytical column: GMHLX + G3000HXL (Tosoh Corporation)

5). Average particle size of primary particles (1) Measuring device: Laser diffraction particle size analyzer (Horiba, LA-920)
(2) Measurement conditions: Distilled water is added to the measurement cell, and the volume-median particle size (D ₅₀ ) is measured at a concentration in which the absorbance is in an appropriate range.

6). Toner particle size (1) Preparation of dispersion: Disperse (Emulgen 109P (manufactured by Kao, polyoxyethylene lauryl ether, HLB: 13.6) 5% by weight aqueous solution) add 10 mg of measurement sample to an ultrasonic disperser. Disperse for 1 minute, and then add 25 ml of electrolyte (Isoton II (manufactured by Beckman Coulter)) and further disperse for 1 minute with an ultrasonic disperser to obtain a dispersion.
(2) Measuring device: Coulter Multisizer II (Beckman Coulter, Inc.)
Aperture diameter: 100 μm
Measurement particle size range: 2-60μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter)
(3) Measurement conditions: 100 ml of electrolyte solution and dispersion were added to a beaker, and the volume-median particle size (D ₅₀ ) of 30,000 particles at a concentration at which the particle size of 30,000 particles can be measured in 20 seconds. Ask for.

Production example 1 of polyester
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (34090 g), fumaric acid (5800 g) and dibutyltin oxide (15 g) were placed in a four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple. The mixture was stirred at 230 ° C. in a nitrogen atmosphere and reacted until the softening point measured according to ASTM D36-86 reached 100 ° C. to obtain Resin A. Resin A had a softening point of 98 ° C., a glass transition point of 56 ° C., an acid value of 22.4 mgKOH / g, and a number average molecular weight of 2930.

Production example 2 of polyester
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 12250g, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 21125g, Terephthalic acid 15272g and Dibutyltin oxide 15g In a four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple, stirred at 220 ° C in a nitrogen atmosphere, and the softening point measured according to ASTM D36-86 reaches 112 ° C To give a resin B. Resin B had a softening point of 110 ° C, a maximum endothermic peak temperature of 75 ° C, a crystallinity index of 1.51, a glass transition point of 70 ° C, an acid value of 5.9 mgKOH / g, and a number average molecular weight of 4088.

Production example 3 of polyester
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 16800g, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 15600g, terephthalic acid 11000g, alkenyl succinic anhydride 1544 g of the product and 15 g of dibutyltin oxide were placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and stirred at 230 ° C. for 4 hours in a nitrogen atmosphere. Thereafter, 4600 g of trimellitic anhydride was added and reacted until the softening point measured in accordance with ASTM D36-86 reached 125 ° C. to obtain Resin C. Resin C had a softening point of 123 ° C., a maximum endothermic peak temperature of 72 ° C., a crystallinity index of 1.70, a glass transition point of 63 ° C., an acid value of 20.0 mgKOH / g, and a number average molecular weight of 3400.

Colorant Production Example 1
3,000 parts by weight of phthalic anhydride, 4500 parts by weight of urea, 530 parts by weight of cuprous chloride, 10 parts by weight of ammonium molybdate and 8000 parts by weight of “Hisol P” (manufactured by Nippon Oil Co., Ltd., alkylbenzene) The mixture was put into a reaction vessel, heated to 170 to 200 ° C. with stirring, and reacted for 4 to 7 hours to obtain a crude copper phthalocyanine slurry (solid content (crude copper phthalocyanine) 26.5% by weight).

  Crude copper phthalocyanine slurry obtained in a SUS316 vibratory fluid dryer (Chuo Kako Co., Ltd., model VHS30) filled with 3/8 inch diameter steel balls as a grinding aid up to 70% of the internal volume. The copper phthalocyanine particles were dried while being ground by continuous operation while supplying a fixed amount of water with a pump. Solvent removal was completed in about 2 hours of operation. The refined copper phthalocyanine is heated (90-100 ° C.) with 20 to 30 times its 2% by weight sodium hydroxide aqueous solution and 2% by weight sulfuric acid aqueous solution, respectively, for impurities (unreacted products, by-products, etc.) ), Washed with water and dried to obtain a clear copper phthalocyanine pigment A having an average particle size of 60 nm.

Colorant Production Example 2
The process of removing impurities from the refined copper phthalocyanine and rinsing with water is performed in the same manner as in Production Example 1, and then excess water is filtered to form an aqueous paste of a clear copper phthalocyanine pigment having an average particle diameter of 60 nm. Press cake B (solid content (copper phthalocyanine pigment) 47.9 wt%) was obtained.

Colorant Production Example 3
As a grinding aid, an aqueous solution of a clear copper phthalocyanine pigment having an average particle diameter of 30 nm was prepared in the same manner as in Production Example 2 except that 50 parts by weight of sodium chloride was used relative to 100 parts by weight of the solid content of the crude copper phthalocyanine slurry. A pasty press cake C (solid content (copper phthalocyanine pigment) 48.5% by weight) was obtained.

Production Example 1 of Colorant Masterbatch
70 parts by weight of fine powder of resin A, 30 parts by weight of copper phthalocyanine pigment A and 30 parts by weight of water were charged into a Hensyl mixer and mixed for 5 minutes to be wet. Next, this mixture was charged into a kneader mixer and gradually heated. The resin was melted at approximately 90 to 110 ° C. and kneaded in a state where water was mixed, and kneading was continued at 90 to 110 ° C. for 20 minutes while evaporating the water.

  Further, kneading was continued at 120 ° C. to evaporate the remaining water, followed by dehydration drying. Kneading at 120-130 ° C for 10 minutes, cooling, melt-kneading with a three-roll type kneader, cooling, coarsely pulverizing, and masterbatch of colorant containing copper phthalocyanine pigment at a concentration of 30% by weight A was obtained. When this was placed on a slide glass, heated and melted, and observed with a microscope, all the pigment particles were finely dispersed, and no coarse particles were observed.

Production Example 2 of Colorant Masterbatch
Instead of copper phthalocyanine pigment A, a copper phthalocyanine pigment press cake B was used so that the copper phthalocyanine pigment was 30 parts by weight, and water was not used. A masterbatch B of colorant containing at a concentration of 30% by weight was obtained. When this was placed on a slide glass, heated and melted, and observed with a microscope, all the pigment particles were finely dispersed, and no coarse particles were observed.

Production Example 3 of Colorant Masterbatch
Instead of copper phthalocyanine pigment A, a copper phthalocyanine pigment press cake C was used so that the copper phthalocyanine pigment was 30 parts by weight, and water was not used. A colorant masterbatch C containing at a concentration of 30% by weight was obtained. When this was placed on a slide glass, heated and melted, and observed with a microscope, all the pigment particles were finely dispersed, and no coarse particles were observed.

Production Example 4 of Colorant Masterbatch
Use 70 parts by weight of fine powder of resin B instead of resin A, use copper phthalocyanine pigment press cake B instead of copper phthalocyanine pigment A so that the copper phthalocyanine pigment is 30 parts by weight, and use water. A master batch D of a colorant containing a copper phthalocyanine pigment at a concentration of 30% by weight was obtained in the same manner as in Production Example 1 except that there was not. When this was placed on a slide glass, heated and melted, and observed with a microscope, all the pigment particles were finely dispersed, and no coarse particles were observed.

Example 1
In a 5 liter stainless steel kettle, resin A 442 g, colorant masterbatch A 83 g and nonionic surfactant (polyoxyethylene lauryl ether (EO = 12 mol addition), cloud point: 98 ° C., HLB: 15.3) 40 g was melted at 170 ° C. with stirring at 200 r / min with a Kai-type stirrer. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and use potassium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 226g was dripped. Subsequently, deionized water was added dropwise at a rate of 5 g / min with stirring at 200 r / min with a Kai-type stirrer, and a total of 2000 g was added. During this time, the temperature of the system was maintained at 95 ° C. to obtain a dispersion containing primary particles. The average particle size of the primary particles was 0.153 μm, the solid concentration in the dispersion was 24.8% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh.

  350 g of the resulting dispersion containing primary particles was put into a 1 liter container, and then an aqueous solution of 2.14 g of calcium chloride was added as a flocculant under stirring at 100 r / min with a chi-type stirrer at room temperature. Stir for 10 minutes. Thereafter, while stirring, the mixture was heated from room temperature to 81 ° C. at a heating rate of 1 ° C./5 min (generation of aggregated particles). The pH in the aggregation process was 5.9.

When the temperature of the dispersion reached 81 ° C., the heating was stopped and the mixture was gradually cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume-median particle size (D ₅₀ ) of the colored resin fine particles was 6.1 μm, and the water content was 0.3% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The obtained cyan toner had a volume median particle size (D ₅₀ ) of 6.7 μm and a softening point of 88 ° C. The results are shown in Table 1.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Example 2
A dispersion containing primary particles was obtained in the same manner as in Example 1 except that 83 g of the colorant master batch B was used instead of the colorant master batch A. The average particle size of the primary particles was 0.148 μm, the solid concentration in the dispersion was 23.9% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh.

  350 g of the obtained dispersion containing primary particles was put into a 1 liter container, and then an aqueous solution of 2.14 g of calcium chloride was added as a flocculant as a flocculant with stirring at 100 r / min with a chi-type stirrer. Stir for 10 minutes. Thereafter, while stirring, the mixture was heated from room temperature to 80 ° C. at a heating rate of 1 ° C./min (generation of aggregated particles). The pH in the aggregation process was 5.8.

The temperature was raised from 80 ° C. at 1 ° C./10 min. When the temperature of the dispersion reached 95 ° C., the heating was stopped and the mixture was gradually cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume median particle size (D ₅₀ ) of the colored resin fine particles was 5.8 μm, and the water content was 0.2% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The obtained cyan toner had a volume median particle size (D ₅₀ ) of 6.0 μm and a softening point of 89 ° C. The results are shown in Table 1.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Example 3
A dispersion containing primary particles was obtained in the same manner as in Example 1 except that 83 g of the colorant master batch C was used instead of the colorant master batch A. The average primary particle size was 0.117 μm, the solid concentration in the dispersion was 25.0% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh.

  350 g of the resulting dispersion containing primary particles is put into a 1 liter container, and then an aqueous solution of 2.10 g of calcium chloride is added as a flocculant under stirring at 100 r / min with a chi-type stirrer at room temperature. Stir for 10 minutes. Thereafter, while stirring, the mixture was heated from room temperature to 80 ° C. at a heating rate of 1 ° C./min (generation of aggregated particles). The pH in the aggregation process was 6.0.

The temperature was raised from 80 ° C. at 1 ° C./10 min. When the temperature of the dispersion reached 96 ° C., the heating was stopped and the mixture was gradually cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume median particle size (D ₅₀ ) of the colored fine resin particles was 5.0 μm, and the water content was 0.3% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The obtained cyan toner had a volume-median particle size (D ₅₀ ) of 5.2 μm and a softening point of 89 ° C. The results are shown in Table 1.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Example 4
In a 5 liter stainless steel kettle, resin A 165 g, colorant masterbatch A 50 g and nonionic surfactant (polyoxylauryl ether (EO = 12 mol addition), cloud point: 98 ° C., HLB: 15.3) 100 g Was melted at 170 ° C. with stirring at 200 r / min with a Kai-type stirrer. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and use potassium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 64.5g was dripped. Subsequently, deionized water was added dropwise at a rate of 5 g / min with stirring at 200 r / min with a Kai-type stirrer, and a total of 1225 g was added. During this time, the temperature of the system was maintained at 95 ° C. to obtain a dispersion containing primary particles. When the average particle size of the primary particles was 0.245 μm, the solid concentration in the dispersion was 21.8% by weight, and the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh, 0.05 g of residual components remained on the wire mesh.

  On the other hand, in a 5 liter stainless steel kettle, 200 g of Resin A and 20 g of nonionic surfactant (polyoxylauryl ether (EO = 12 mol addition), cloud point: 98 ° C., HLB: 15.3) are mixed with a chi-type stirrer. It was melted at 170 ° C. with stirring at 200 r / min. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and use potassium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 90.4g was dripped. Subsequently, deionized water was added dropwise at a rate of 5 g / min with stirring at 200 r / min with a Kai-type stirrer, and a total of 1043 g was added. During this time, the temperature of the system was maintained at 95 ° C. to obtain a dispersion containing resin particles. The average particle size of the primary particles was 0.148 μm, the solid concentration in the dispersion was 16.0% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a wire mesh of 200 mesh (opening: 105 μm).

  200 g of the resulting dispersion containing primary particles and 100 g of the dispersion containing resin particles were placed in a 1 liter container and mixed at room temperature. Next, under stirring at 100 r / min with a Kai-type stirrer, an aqueous solution for 1.60 g of calcium chloride as a flocculant was added to this mixture and stirred at room temperature for 10 minutes. Thereafter, while stirring, the mixture was heated from room temperature to 80 ° C. at a heating rate of 1 ° C./min (generation of aggregated particles). The pH in the aggregation process was 5.8.

The temperature was raised from 80 ° C. at 1 ° C./10 min. When the temperature of the dispersion reached 95 ° C., the heating was stopped and the mixture was gradually cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume median particle size (D ₅₀ ) of the colored resin fine particles was 5.8 μm, and the water content was 0.2% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The obtained cyan toner had a volume median particle size (D ₅₀ ) of 6.0 μm and a softening point of 88 ° C. The results are shown in Table 1.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Example 5
A dispersion containing primary particles in the same manner as in Example 1 except that 83 g of the colorant masterbatch D was used instead of the masterbatch A of the colorant, and the dripping amount of the aqueous potassium hydroxide solution was changed to 207.8 g. Got. The average primary particle size was 0.152 μm, the solid concentration in the dispersion was 24.3% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh.

  350 g of the resulting dispersion containing primary particles was put in a 1 liter container, and then an aqueous solution of 1.60 g of calcium chloride was added as a flocculant as a flocculant with stirring at 100 r / min with a chi-type stirrer. Stir for 10 minutes. Thereafter, while stirring, the mixture was heated from room temperature to 80 ° C. at a heating rate of 1 ° C./min (generation of aggregated particles). The pH in the aggregation process was 5.6.

The temperature was raised from 80 ° C. at 1 ° C./10 min. When the temperature of the dispersion reached 95 ° C., the heating was stopped, and the mixture was cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume-median particle size (D ₅₀ ) of the colored resin fine particles was 5.2 μm, and the water content was 0.2% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The obtained cyan toner had a volume-median particle size (D ₅₀ ) of 5.6 μm and a softening point of 104 ° C. The results are shown in Table 1.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Example 6
A material with a total weight of 3 kg consisting of 65 parts by weight of resin B, 35 parts by weight of resin C and 17 parts by weight of masterbatch B is put into a 10 liter Henschel mixer and premixed for 3 minutes at a blade rotation speed of 2300 r / min. It was. The softening point of the mixed resin consisting of 65 parts by weight of resin D and 35 parts by weight of resin E was 117 ° C.

  The obtained mixture was supplied to an open roll type biaxial continuous kneader (manufactured by Mitsui Mining Co., Ltd., trade name: Kneedex) with a table feeder and kneaded to obtain a kneaded product. The open roll type biaxial continuous kneader used at this time has a roll outer diameter of 0.14 m and an effective roll length of 0.8 m, and the operating conditions are a high rotation side roll (front roll) rotation speed of 75 r / min, low The rotation speed of the rotation side roll (rear roll) was 50 r / min, and the roll gap was 0.1 mm. The heating and cooling medium temperature in the roll is 150 ° C on the raw material input side of the high-rotation roll, 130 ° C on the kneaded material discharge side, 35 ° C on the raw material input side of the low-rotation roll, and the kneaded material discharge side. The temperature of was set to 30 ° C. At this time, the temperature of the melt-kneaded product was 107 ° C. The feed rate of the raw material mixture was 5 kg / hour, and the average residence time was about 5 minutes. The obtained toner kneaded product was cooled with a cooling belt and then roughly crushed with a mill having a 2 mmφ screen.

  210 g of crushed material obtained in a 5 liter stainless steel kettle and 40 g of nonionic surfactant (polyoxyethylene lauryl ether (EO = 12 mol addition), cloud point: 98 ° C., HLB: 15.3) The mixture was melted at 170 ° C. with stirring at 200 r / min. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and use potassium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 90 g was dropped. Subsequently, deionized water was added dropwise at a rate of 5 g / min with stirring at 300 r / min with a Kai-type stirrer, and a total of 1600 g was added. During this time, the temperature of the system was maintained at 95 ° C. to obtain a dispersion containing primary particles. The volume-median particle size of the primary particles was 0.110 μm, the solid concentration in the dispersion was 20.4% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh: 105 μm) wire mesh.

  400 g of the resulting dispersion containing primary particles is put in a 2 liter container, and an aqueous solution of 1.21 g of calcium chloride is added as an aggregating agent, and heated from room temperature to 80 ° C. with a heating rate of 1 ° C./min. (Generation of aggregated particles). The pH in the aggregation process was 5.9.

Furthermore, the temperature was raised from 80 ° C. at 1 ° C./10 min. When the temperature of the dispersion reached 85 ° C., the heating was stopped, and stirring was continued until the temperature returned to room temperature (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain fine particles (toner) in which aggregated particles were united. The volume median particle size (D ₅₀ ) of the colored fine resin particles was 5.0 μm, the softening point was 101 ° C., and the water content was 0.2% by weight. To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner.

  When a silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) having an average particle diameter of 60 μm was added to the cyan toner obtained, and the mixed developer was printed with a commercially available copying machine, a good image was obtained.

Comparative Example 1
A dispersion liquid containing primary particles was obtained in the same manner as in Example 1 except that the amount of resin A used was changed to 500 g, and copper phthalocyanine pigment A 25 g was used instead of master batch A of the colorant. The average primary particle size was 0.233 μm, the solid concentration in the dispersion was 24.4% by weight, and nothing was left on the wire mesh even when the dispersion was passed through a 200 mesh (mesh size: 105 μm) wire mesh.

  350 g of the resulting dispersion containing primary particles is put into a 1 liter container, and then an aqueous solution of 2.10 g of calcium chloride is added as a flocculant under stirring at 100 r / min with a chi-type stirrer at room temperature. Stir for 10 minutes. Thereafter, the mixture was heated from room temperature at a heating rate of 1 ° C./5 min with stirring (generation of aggregated particles). The pH in the aggregation process was 5.8.

When the temperature of the dispersion reached 83 ° C., the heating was stopped and the mixture was gradually cooled to room temperature with stirring (generation of coalesced particles). The contents were suction filtered, washed, and dried to obtain colored resin fine particles. The volume-median particle size (D ₅₀ ) of the colored resin fine particles was 6.3 μm, and the water content was 0.2% by weight.

To 100 parts by weight of the colored resin fine particles, 1.0 part by weight of hydrophobic silica (TS530, number average particle diameter: 8 nm, manufactured by Wacker Chemie) was externally added using a Henschel mixer to obtain a cyan toner. The resulting cyan toner had a volume median particle size (D ₅₀ ) of 6.5 μm and a softening point of 88 ° C. The results are shown in Table 1.

  A silicon-coated ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd.) with an average particle size of 60 μm was added to the obtained cyan toner, and the mixed developer was printed with a commercially available copying machine. It was inferior compared with Examples 1-6.

Comparative Example 2
In a 5 liter stainless steel kettle, non-ionic surfactant was not used, and only 442 g of resin A and 83 g of colorant masterbatch B were melted at 170 ° C. with stirring at 200 r / min with a Kai-type stirrer. . The contents were stabilized at 95 ° C., and 226 g of a potassium hydroxide aqueous solution (concentration: 5% by weight) was added dropwise as a neutralizing agent with stirring at 200 r / min with a chi-type stirrer. Subsequently, while the deionized water was started to be dripped under stirring at 200 r / min with a chi-type stirrer, the melt viscosity became high, making it difficult to prepare a dispersion containing primary particles, and production of the toner was discontinued. .

[Evaluation of dispersibility of colorant]
The toner sample was embedded in polyester, and an ultrathin section sample was prepared with an ultramicrotome. A sample was photographed with a transmission electron microscope (JEOL 2000, JEM-2000FX) under the conditions of an acceleration voltage of 80 kV and a magnification of 20,000 times. The dispersion state of the colorant in the toner on the photograph was visually observed and evaluated in five stages (5: good to 1: poor). The results are shown in Table 1.

  From the above results, it can be seen that in Examples 1 to 6, toners having a small particle diameter with good dispersibility of the colorant are obtained. On the other hand, in Comparative Example 1 in which the master batch of the colorant was not used, the dispersibility of the colorant was insufficient, and in Comparative Example 2 in which the nonionic surfactant was not used, primary particles were produced. You can't do it.

  The toner for electrophotography obtained by the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (10)

A method for producing an electrophotographic toner comprising a binder resin and a colorant, wherein the binder resin and a colorant masterbatch in which the colorant is dispersed in the resin are mixed, and the HLB is 12 to 18 An electrophotographic process comprising a step (1) of producing primary particles in an aqueous medium containing 99% by weight or more of water in the presence of a nonionic surfactant, and a step (2) of aggregating and coalescing the primary particles. Of manufacturing toner.   2. The method for producing an electrophotographic toner according to claim 1, wherein the primary particles are obtained after undergoing a step of melt-kneading at least a binder resin and a master batch of a colorant.   The method for producing an electrophotographic toner according to claim 1, wherein the melt kneading is performed using an open roll type biaxial kneader.   4. The method for producing an electrophotographic toner according to claim 1, wherein the master batch of the colorant is a flushing master batch.   5. The method for producing an electrophotographic toner according to claim 4, wherein the flushing master batch is obtained from a colorant press cake ground by salt milling.   6. The method for producing an electrophotographic toner according to claim 5, wherein the solid content of the press cake is 30 to 70% by weight.   The average particle size of the colorant is 5 to 100 nm, the average particle size of the primary particles in step (1) is 0.05 to 3 µm, and the average particle size of the colorant is smaller than the average particle size of the primary particles. 6. A method for producing an electrophotographic toner as described in any one of 6 above.   In the step (1), an aqueous medium is added at a rate of 0.1 to 50 g / min per 100 g of the mixture to a mixture containing at least a binder resin, a colorant and a nonionic surfactant. A method for producing the electrophotographic toner according to claim.   The method for producing an electrophotographic toner according to claim 1, wherein the acid value of the binder resin mixed with the master batch is equal to or higher than the acid value of the resin used for the master batch. The method for producing an electrophotographic toner according to claim 1, wherein the cloud point of the nonionic surfactant is 70 to 105 ° C.