JP2006106679A - Process for preparing toner for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for preparing a toner for electrophotography with a small particle size and in a high yield without being limited by the kind of a binder resin, and to provide a toner for electrophotography obtained by the preparation process. <P>SOLUTION: The process for preparing a toner for electrophotography comprising a binder resin and a colorant includes a step of preparing fine particles of the binder resin to have a volume-median particle size (D<SB>50</SB>) of from 0.05 to 3 μm in an aqueous medium in the presence of a nonionic surfactant within a temperature range of from 10°C below to 10°C above a cloud point of the nonionic surfactant. The toner for electrophotography is obtained by the above process, wherein the toner contains ≥60 wt.% of a crystalline polyester and has a volume-median particle size (D<SB>50</SB>) of from 1 to 7 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  In recent years, it has been desired to reduce the particle size of toner in order to improve image quality. The toner production method includes a melt kneading pulverization method and a wet production method such as an emulsion aggregation method. When a toner using a binder resin mainly composed of crystalline polyester is produced by the melt kneading pulverization method, the toner is pulverized. Control becomes difficult and impractical.

Patent Document 1 and Patent Document 2 disclose inventions relating to production by an emulsion aggregation method, which is a wet production method. However, the method described in Patent Document 1 is limited to resins that can be dissolved in an organic solvent, and the yield is extremely reduced in the case of a resin having a low solubility in an organic solvent. Moreover, in the method of patent document 2, it is limited to the crystalline polyester which consists of a specific raw material monomer.
JP 2003-122051 A (Claim 1) JP 2001-30596A (Claims 1 and 2)

  An object of the present invention is not limited to the type of binder resin, and is to provide a method for producing an electrophotographic toner having a small particle size with a high yield and an electrophotographic toner obtained by the production method. is there.

That is, the present invention
[1] A method for producing a toner for electrophotography comprising a binder resin and a colorant, wherein in the presence of a nonionic surfactant, the nonionic surfactant is 10 ° C. above and below the cloud point of the nonionic surfactant. And a method for producing an electrophotographic toner comprising a step of atomizing the binder resin to a volume-median particle size (D ₅₀ ) of 0.05 to 3 μm in an aqueous medium within the temperature range of [2] and [1] An electrophotographic toner obtained by the described production method, wherein the toner contains 60% by weight or more of crystalline polyester and has a volume median particle size (D ₅₀ ) of 1 to 7 μm. .

  According to the present invention, an electrophotographic toner having a small particle diameter can be obtained with high yield without being limited to the type of 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 include crystalline polyesters, amorphous polyesters, polyester polyamides, vinyl resins such as styrene-acrylic resins, and hybrid resins having a plurality of resin components. It may be used. From the viewpoint of low-temperature fixability, it is preferable to contain at least a crystalline polyester. In this case, the binder resin used together with the crystalline polyester is a hybrid resin in which an amorphous polyester component and a vinyl resin component are partially chemically bonded from the viewpoint of compatibility with the crystalline polyester and toner fixing properties. Amorphous polyester is preferred, and amorphous polyester is more preferred.

  The content of the crystalline polyester in the binder resin is preferably 60% by weight or more, more preferably 75% 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 75% by weight or more, and further preferably 80 to 95% by weight.

  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.

  The crystalline polyester in the present invention can be produced by a condensation polymerization reaction of ordinary raw material monomers. That is, it can be produced by dehydrating condensation polymerization of a carboxylic acid component and an alcohol component in the presence of a catalyst.

  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-C3) 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.

  The carboxylic acid component contains 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. Preferably it is. 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 the charging property and durability of the toner, aromatic dicarboxylic acid compounds having an aromatic ring such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and alicyclic dicarboxylic acid compounds such as cyclohexanedicarboxylic acid are used. It is preferably 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%.

  On the other hand, as alcohol components, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptane Aliphatic diols such as diol, 1,8-octanediol, neopentyl glycol, 1,4-butenediol; polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2 ) -2,2-bis (4-hydroxyphenyl) propane, an aromatic diol such as an alkylene oxide adduct of bisphenol A; a trihydric or higher polyhydric alcohol such as glycerin or pentaerythritol.

  From the viewpoint of promoting the crystallinity of the polyester, the alcohol component preferably contains an aliphatic diol having 2 to 8 carbon atoms. Among them, α, ω-linear alkanediol, more preferably 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 all alcohol components. % Content is desirable.

  That is, in order to promote the crystallinity of 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 contains 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 condensation polymerization of 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 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 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.

  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 is preferable that an alkylene oxide adduct of bisphenol A such as an alkylene (2 to 3 carbon) oxide (average addition mole number 1 to 16) adduct of bisphenol A such as propane is contained.

  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 amorphous polyester preferably has a softening point of 95 to 160 ° C and a glass transition point of 50 to 75 ° C.

  The number average molecular weight of the amorphous polyester is preferably from 1,000 to 10,000, more preferably from 1,000 to 50,000, and even more preferably from 1,000 to 12,000, from the viewpoints of durability and fixability.

  The crystalline polyester and amorphous polyester in the present invention preferably have an acid group at the molecular chain end. 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 and the amorphous 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 end of the molecular chain is 0.015 to 0.9 mmol per gram of crystalline polyester or amorphous polyester. Preferably, 0.08 to 0.85 mmol is more preferable, 0.15 to 0.8 mmol is more preferable, and 0.25 to 0.75 mmol is further preferable.

  The acid value of the crystalline polyester and the amorphous polyester is, for example, 1 to 1 g per 1 g of the crystalline polyester or amorphous polyester from the viewpoint of stabilizing the emulsified particles and obtaining a small particle size toner with a sharp particle size distribution. 50 mg KOH / g is preferred, 5-48 mg KOH / g is more preferred, 10-45 mg KOH / g is more preferred, and 15-40 mg KOH / g is even more preferred.

  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 and the amorphous 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, preferably 20 mol% or less from the same viewpoint. Is more preferably 10 mol% or less, further preferably 5 mol% or less, and further preferably 2 mol% or less.

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

  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, various dyes xanthene, etc. may be used in conjunction with one or more kinds.

  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.

  The toner in the present invention preferably contains a release agent. By adding a release agent, the releasability is improved in the fixing step, and in the contact heating type fixing method, the release oil applied to the fixing roll can be reduced or eliminated.

  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.

  The melting point of the release agent is preferably 50 to 120 ° C., more preferably below the melting point of the binder resin, in consideration of the blocking resistance and the influence on the low-temperature fixability of the binder resin. The amount of the release agent is preferably 1 to 20 with respect to 100 parts by weight of the binder resin in consideration of the effect on the low temperature offset, the influence on the charging property, and the influence of the spent of the toner resin on the carrier. Parts by weight, more preferably 2 to 15 parts by weight, still more preferably 2 to 10 parts by weight.

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

  The toner production method of the present invention is characterized by the step of atomizing the binder resin in an aqueous medium in the presence of a nonionic surfactant in a specific temperature range. After aggregating the binder resin (aggregation step) to obtain aggregated particles, the aggregated particles are coalesced (coalescence step), and the resulting coalesced particles are separated, washed and dried, and electrophotographic Toner can be obtained.

  When the binder resin and the nonionic surfactant are mixed, heated, and stirred, the viscosity of the mixture decreases, and the binder resin can be atomized. It has been found that this 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 of 100 ° C. or higher or a glass transition point. Even in the case of the binder resin having 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 for recovery of organic solvents and maintenance of the working environment as used in Patent Documents 1 and 2, etc. There is also an advantage that a resin dispersion can be produced economically. 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.

  Therefore, as a result of further investigation on the conditions for compatibilizing the nonionic surfactant with the binder resin, it was found that the change in the properties of the nonionic surfactant at the cloud point is an important factor.

  That is, generally, when the temperature of the aqueous solution of the nonionic surfactant is increased, the transparent aqueous solution starts to become cloudy at a certain temperature. This temperature is called the cloud point. This occurs when the surfactant is dissolved in water and the hydrogen bond between the hydrophilic group in the molecule and water is broken. Therefore, at temperatures above the cloud point, the nonionic surfactant becomes oil-soluble and loses its surface activity. Therefore, the present inventors have paid attention to the fact that this property of the nonionic surfactant can be used as a means for controlling the particle size of the resin fine particles. That is, by using a nonionic surfactant in a much larger amount than that conventionally used to assist emulsification of resin fine particles, the dispersion or emulsification system is controlled at a temperature near its cloud point. The nonionic surfactant can be dissolved in the binder resin, and surprisingly, the particle diameter of the resin fine particles can be easily changed.

  When atomizing the binder resin, it is important to keep the temperature in the system within a temperature range of 10 ° C, preferably 8 ° C, more preferably 5 ° C above and below the cloud point of the nonionic surfactant. is there. When the temperature is higher than 10 ° C from the cloud point of the nonionic surfactant, the dispersibility of the nonionic surfactant is lowered. When the temperature is higher than 10 ° C from the cloud point, the dispersion efficiency is lowered.

  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.

  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, more preferably 8 parts by weight or more, and 10 parts by weight or more with respect to 100 parts by weight of the binder resin. Is more preferable, and 20 parts by weight or more is more preferable. On the other hand, from the viewpoint of controlling the nonionic surfactant remaining in the toner, it is preferably 80 parts by weight or less, more preferably 70 parts by weight or less, and even more preferably 60 parts by weight or less. From the viewpoint of making these compatible, the amount of the nonionic surfactant used is preferably 5 to 80 parts by weight, more preferably 8 to 80 parts by weight, and more preferably 10 to 70 parts by weight with respect to 100 parts by weight of the binder resin. Is more preferable, and 20 to 60 parts by weight is more preferable.

  The cloud 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.

  In the particle aggregation and coalescence process, it is desirable to perform slow aggregation and rapid coalescence from the viewpoint of controlling the toner particle diameter. From this viewpoint, the aggregation step is preferably performed at a temperature near the cloud point of the nonionic surfactant, and the coalescing step is preferably performed at a temperature equal to or higher than the cloud point of the nonionic surfactant. This temperature adjustment means agglomeration at a temperature at which the surfactant works effectively, and coalescence at a temperature at which the surfactant loses its effect.

In the aggregation / unification step, since the binder resin needs to be fused, it is preferable to perform both in the vicinity of the softening point of the binder resin. Therefore, from the viewpoint of toner shape control and particle size control performed from the aggregation process to the coalescence process, the cloud point (Tc) of the nonionic surfactant and the softening point (Ts) of the binder resin are
Ts−30 <Tc <Ts
It is preferable that
Ts−30 <Tc <Ts−10
It is more preferable that the relationship is

  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.

  In the step of atomizing the binder resin, for example, the mixture of the binder resin and the nonionic surfactant is stirred and mixed in the system with water (preferably deionized water or distilled). Water) is preferably added dropwise. At this time, it is preferable to take care so that the binder resin compatible with the nonionic surfactant does not separate from water.

  The amount of water mixed is preferably 100 parts by weight or more with respect to 100 parts by weight of the binder resin from the viewpoint of obtaining uniform aggregated particles in the subsequent process.

  The dispersed particle size of the binder resin in the dispersion can be controlled by the amount of the nonionic surfactant, the stirring force, and the dropping rate of water.

  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 control factor of the resin dispersed particle diameter 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 resulting dispersion. 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 content concentration in the system for preparing the binder resin dispersion is preferably 7 to 50% by weight, more preferably 7 to 40%, from the viewpoint of the stability of the dispersion and the handling of the dispersion in the aggregation step. % By weight, more preferably 10 to 30% by weight. The solid content includes non-volatile components such as a resin and a nonionic surfactant.

The volume-median particle size (D ₅₀ ) of the atomized binder resin is selected according to the particle size of the toner to be obtained from the resin, but is 0.05 to 3 μm, and a higher quality toner is obtained. Therefore, it is preferably 0.05 to 0.5 μm, more preferably 0.05 to 0.3 μm, and still more preferably 0.05 to 0.2 μm.

  An additive such as a colorant, a release agent, and a charge control agent may be added in any step. For example, before aggregating the finely divided binder resin, the dispersion of the binder resin and the colorant are added. The dispersion particles and the like can be mixed to obtain aggregated particles containing at least a binder resin and a colorant as constituent components.

  The dispersion containing the atomized binder resin is preferably cooled to room temperature before proceeding to the aggregation process from the viewpoint of producing a toner having a small particle diameter in a high yield.

  If necessary, a colorant and other additives are mixed with the dispersion liquid of the binder resin as a dispersion liquid, for example, and grown into aggregated particles containing at least the binder resin and the colorant as constituent components.

  The solid content concentration in the system in the coagulation step can be adjusted by adding water to the binder resin dispersion as necessary, and 5 to 50% by weight is preferable in order to cause uniform aggregation. 5 to 30% by weight is more preferable, and 5 to 20% by weight is more preferable.

  Further, the pH in the system in the aggregation step is preferably 2 to 10, more preferably 4 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. 4.5 to 7.5 is more preferable.

  From the same viewpoint, the temperature in the aggregation process system 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.

  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, 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. From the viewpoint of controlling charging characteristics, a metal complex, a quaternary salt cationic surfactant is more preferable.

  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.

  Aggregated particles containing at least the binder resin and the colorant obtained in the aggregating step are heated and united.

  The heating temperature for coalescing the aggregated particles is as follows: from the viewpoint of the target toner particle size, particle size distribution, shape control, and particle fusing properties, the softening point of the binder resin is −10 ° C. The softening point is preferably −5 ° C. or more, more preferably the softening point + 10 ° C. or less, and further preferably the softening point or more and the softening point + 10 ° C. or less. The stirring speed is preferably a speed at which the aggregated particles do not settle.

In the aggregation process and the coalescence process, from the viewpoint of narrowing the particle size distribution of the toner in order to improve the image quality, the temperature of the atomized binder resin is increased while holding at a temperature of at least two stages for a certain period of time. Is preferred. Specifically, the atomized binder resin is at least represented by the formulas (I) and (II):
_{(I) Ts-100 <T} 1 <Ts-5
(II) T ₁ <T ₂ ≦ T ₁ +20
(In the formula, Ts represents the softening point (° C.) of the binder resin)
At T ₁ ° C. and T ₂ ° C. to satisfy, it is preferable to retain each 30-180 minutes. T ₁ ° C and T ₂ ° C are average temperatures within the holding time, and both are preferably controlled within a range of ± 2 ° C, more preferably ± 1 ° C, and even more preferably ± 0.5 ° C. desirable.

In the two-stage temperature increase, aggregated particles having a certain particle size distribution are mainly generated at T ₁ ° C, and the generated aggregated particles are united at T ₂ ° C. Particles with a small particle size with a relatively high surface energy have a faster particle growth than particles with a relatively small surface energy and a relatively low surface energy. It is presumed that the particle size distribution of the obtained particles becomes narrow.

In the formula (I), T ₁ is higher than (Ts-100) ° C. from the viewpoint of controlling the viscosity of the binder resin and promoting more uniform aggregation, and from the viewpoint of preventing rapid aggregation and particle enlargement. Therefore, the temperature is preferably lower than (Ts-5) ° C. From these viewpoints, the formula (I) is preferably Ts-100 <T ₁ <Ts-20.
More preferably, Ts−90 <T ₁ <Ts−20
It is.

The volume-median particle size (D ₅₀ ) of the aggregated particles produced at the end of holding at T ₁ ° C depends on the particle size of the toner to be finally produced, but the aggregated particles obtained at the subsequent T ₂ ° C. From the viewpoint of narrowing the particle size distribution or the toner particle size distribution, 1 to 6 μm is preferable, 1.5 to 5.5 μm is more preferable, and 2 to 5 μm is more preferable.

Further, from the viewpoint of gently generating coalesced particles and narrowing the toner particle size distribution, the formula (II) is preferably T ₁ <T ₂ ≦ T ₁ +15.
And more preferably
T ₁ + 2 ≦ T ₂ ≦ T ₁ +15
It is.

The holding time at T ₁ ° C and T ₂ ° C is preferably 30 to 180 minutes, and more preferably 30 to 90 minutes. It is also possible to further kept at another temperature in the course of raising the temperature from T ₁ to T _2.

When the temperature of the atomized binder resin is raised in an aqueous medium, aggregation starts gradually from around 30 ° C. Therefore, when the binder resin is in the temperature range of 30 ° C. to T ₂ ° C., the viewpoint of generating coalesced particles in which the agglomerated particles are sufficiently coalesced and crushing of the toner particles in a printer or the like equipped with toner From the viewpoint of suppressing the above, 1 hour or more is preferable, and 1 to 8 hours is more preferable. Further, from the viewpoint of preventing the additives (colorant, release agent, etc.) in the particles from aggregating in the coalescing process, 6 hours or less is preferable. From these viewpoints, the time that the binder resin is in the temperature range of 30 ° C. to T ₂ ° C. is preferably 1 to 8 hours, more preferably 1 to 6 hours, further preferably 1.5 to 5 hours, and 1.5 to 4.5 hours. Is more preferable. The toner shape can be controlled by adjusting this time. For example, when the time is shortened, the toner shape tends to be a potato shape, and when the time is lengthened, the toner shape tends to be nearly spherical.

  The obtained coalesced particles are subjected to a solid-liquid separation process such as filtration, a washing process, and a drying process, whereby a toner can be obtained.

  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, maximum peak temperature of endotherm, melting point and glass transition point (1) Softening point Heating a 1g sample at a heating rate of 6 ° C / min using a Koka flow tester (Shimadzu Corporation, CFT-500D) 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. Plot the flow rate of the plunger drop (flow value) of the flow tester against the temperature, and let the temperature at which half the sample flowed out be 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 with amorphous polyester, but is observed when amorphous part is present even with 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 the 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. Subsequently, this solution is filtered using a fluororesin filter (manufactured by Sumitomo Electric Industries, Ltd., FP-200) having a pore size of 2 μm 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 (manufactured by Tosoh Corporation)

5. Resin dispersed particle size and aggregated and coalesced particle size (1) Measuring device: Laser diffraction particle size measuring machine (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 liquid 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 could be measured in 20 seconds. Ask for.

Production Example 1 of Crystalline Polyester
1,6-hexanediol (1652 g), neopentyl glycol (364 g), terephthalic acid (2905 g) and dibutyltin oxide (10 g) were placed in a 5-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple at 200 ° C. Then, the reaction was continued until no terephthalic acid particles were observed, and the reaction was further continued at 8.3 kPa for 1 hour to obtain Resin A. Resin A had a softening point of 115.6 ° C., a maximum endothermic peak temperature (melting point) of 118.6 ° C., a crystallinity index of 0.98, an acid value of 35 mg KOH / g, and a number average molecular weight of 4450.

Production Example 1 of Amorphous Polyester
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (16800 g), fumaric acid (5800 g) and dibutyltin oxide (15 g) were added to 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 B. Resin B had a softening point of 98 ° C., a maximum endothermic peak temperature of 63 ° C., a crystallinity index of 1.6, 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 Amorphous Polyester
33,750 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 325 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 6960 g of fumaric acid, 6723 g of terephthalic acid and The softening point measured according to ASTM D36-86 after putting 15g of dibutyltin oxide into a four-necked flask equipped with a nitrogen inlet tube, dehydrating tube, stirrer and thermocouple, stirring at 230 ° C under nitrogen atmosphere The reaction was carried out until the temperature reached 110 ° C. to obtain Resin C. Resin C had a softening point of 111 ° C, a maximum endothermic peak temperature of 70 ° C, a crystallinity index of 1.59, an acid value of 24.0 mgKOH / g, and a number average molecular weight of 4090.

Production Example 3 of Amorphous Polyester
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 17500 g, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 16250 g, terephthalic acid 11450 g, trimellitic anhydride Place 4800 g, 1600 g of dodecenyl succinic anhydride and 15 g of dibutyltin oxide in a four-necked flask equipped with a nitrogen inlet tube, dehydrator tube, stirrer and thermocouple, stir at 230 ° C in a nitrogen atmosphere, and conform to ASTM D36-86 The resin D was obtained by reacting until the measured softening point reached 125 ° C. Resin D had a softening point of 125 ° C., a maximum endothermic peak temperature of 69 ° C., a crystallinity index of 1.81, an acid value of 21.0 mgKOH / g, and a number average molecular weight of 3390.

Example 1
In a 5 liter stainless steel kettle, 200 g of resin A and 100 g of nonionic surfactant (polyoxyethylene lauryl ether (EO = 9 mol addition), cloud point: 98 ° C., HLB: 15.3) are mixed with a chi-type stirrer. The mixture was melted at 170 ° C. with stirring of / min. Stabilize the contents at 95 ° C, 3 ° C lower than the cloud point of the nonionic surfactant, and add sodium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 68.5g was dripped. Subsequently, deionized water was added dropwise with stirring at 300 r / min using a chi-type stirrer, and a total of 1631.5 g was added. During this period, the system temperature was maintained at 95 ° C., and a resin dispersion containing atomized resin A was obtained through a 200 mesh (mesh opening: 105 μm) wire mesh. The resin particles in the resulting resin dispersion had a volume median particle size of 0.47 μm, a solid concentration of 12.0% by weight, and no resin component remained on the wire mesh.

400 g of the obtained resin dispersion and 40 g of cyan pigment aqueous dispersion (concentration: 5% by weight) were mixed in a 1 liter container at room temperature (25 ° C.). Next, an aqueous solution corresponding to 1 g of calcium chloride is added to this mixture as a flocculant, adjusted to pH = 7 with an aqueous sodium carbonate solution (concentration: 10% by weight), and then at a rotational speed of 5000 r / min using a homomixer. Stir at room temperature for 1 hour. As a result, the resulting mixed dispersion was transferred to a 1 liter autoclave, heated to 105 ° C. (T ₁ ) and stirred at 500 r / min for 6 hours to form aggregated particles. The volume-median particle diameter (D ₅₀ ) of the produced aggregated particles was 5.1 μm.

Thereafter, the temperature was raised to 125 ° C. (T ₂ ), and the mixture was further stirred for 1 hour to coalesce the aggregated particles, and then colored resin fine particle powder was obtained through a suction filtration step, a washing step, and a drying step. The volume median particle size (D ₅₀ ) of the colored fine resin particle powder was 6.7 μm, and the water content was 0.3% by weight. The time from 30 ° C. to T ₂ ° C. was 7 hours and 40 minutes.

To 100 parts by weight of the colored resin fine particle powder, 1.0 part by weight of hydrophobic silica (manufactured by Wacker Chemie, TS530, number average particle size: 8 nm) 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 110 ° C.

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

Example 2
In a 10 liter stainless steel kettle, 1000 g of resin B and 200 g of nonionic surfactant (polyoxyethylene stearyl ether (EO = 20 mol addition), cloud point: 74 ° C., HLB: 13.9) are mixed with a chi-type stirrer. Melt at 170 ° C. with min stirring. The contents were stabilized at 78 ° C, 4 ° C higher than the cloud point of the nonionic surfactant, and a potassium hydroxide aqueous solution (concentration: 5% by weight) was added at 9ml / min with a chi-type stirrer at 200r / min. Added dropwise at speed for 11 minutes. Subsequently, deionized water was added dropwise at a rate of 8 ml / min with stirring at 300 r / min with a Kai-type stirrer, and a total of 18300 g was added. During this time, the temperature of the system was maintained at 78 ° C., and a resin dispersion containing finely divided resin C was obtained through a 200 mesh (mesh: 105 μm) wire mesh. The resin particles in the resulting resin dispersion had a volume median particle size of 0.13 μm, a solid concentration of 20% by weight, and no resin component remained on the wire mesh.

400 g of the obtained resin dispersion and 40 g of cyan pigment aqueous dispersion (concentration: 5% by weight) were mixed at room temperature in a 1 liter container. Next, an aqueous solution corresponding to 1 g of calcium chloride is added to this mixture as a flocculant, adjusted to pH = 6.8 with an aqueous sodium carbonate solution (concentration: 10% by weight), and then at a rotational speed of 5000 r / min using a homomixer. Stir at room temperature for 1 hour. As a result, the resulting mixed dispersion was transferred to a 2 liter four-necked flask, heated to 80 ° C. (T ₁ ), and stirred at 100 r / min for 4.5 hours to form aggregated particles. The volume-median particle size (D ₅₀ ) of the produced aggregated particles was 4.9 μm.

Thereafter, the temperature was raised to 99 ° C. (T ₂ ), and the mixture was further stirred for 1 hour to coalesce the aggregated particles, and then colored resin fine particle powder was obtained through a suction filtration step, a washing step and a drying step. The volume median particle size (D ₅₀ ) of the colored resin fine particle powder was 5.6 μm, and the water content was 0.4% by weight. The time from 30 ° C. to T ₂ ° C. was 6 hours and 10 minutes.

Thereafter, in the same manner as in Example 1, hydrophobic silica was externally added and mixed with a carrier to prepare a developer. The obtained cyan toner had a volume-median particle size (D ₅₀ ) of 5.6 μm and a softening point of 88 ° C.
When the obtained developer was printed with a commercially available copying machine, a good image was obtained.

Example 3
In a 5 liter stainless steel kettle, 260 g of resin C, 140 g of resin D, 20 g of copper phthalocyanine, and nonionic surfactant (polyoxyethylene lauryl ether (EO = 12 mol addition), cloud point: 98 ° C., HLB: 14.6) 80 g was melted at 150 ° 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 add sodium hydroxide aqueous solution (concentration: 5% by weight) as a neutralizing agent while stirring at 200r / min with a chi-type stirrer. 64 g was dropped. Subsequently, deionized water was added dropwise with stirring at 300 r / min with a Kai-type stirrer, and a total of 1270 g was added. During this period, the system temperature was maintained at 95 ° C., and a resin dispersion containing atomized resin A was obtained through a 200 mesh (mesh opening: 105 μm) wire mesh. The resin particles in the resulting resin dispersion had a volume median particle size of 0.15 μm, a solid concentration of 31.0% by weight, and no resin component remained on the wire mesh.
400 g of the obtained resin dispersion is put into a 2 L glass separable flask. Next, an aqueous solution of 1.5 g of calcium chloride as an aggregating agent and an anionic surfactant “Pois 530” manufactured by Kao Corporation are added to this mixture. 0.5 g was added and stirred at 30 ° C. for 10 minutes. Thereafter, deionized water was added to adjust the solid content concentration to 20% by weight. The pH at that time was 6.7.
Thereafter, the temperature was raised to 80 ° C. (T ₁ ) over 1 hour, and the mixture was further heated and stirred for 1 hour to aggregate the pigment-containing resin particles. The volume-median particle diameter (D ₅₀ ) of the produced aggregated particles was 4.8 μm. Thereafter, the temperature was raised to 82 ℃ (T ₂₎ over a period of 15 minutes, and stirred for another 1 hour heating. Then, it was made to cool gradually to room temperature, and colored resin fine particle powder was obtained through the suction filtration process, the washing | cleaning process, and the drying process. The volume median particle size of the colored resin fine particle powder was 5.0 μm, and the water content was 0.3% by weight. The time from 30 ° C. to T ₂ ° C. was 3 hours 30 minutes.

  1.0 part by weight of hydrophobic silica (manufactured by Wacker Chemie, TS530, number average particle diameter: 8 nm) was added externally using a Henschel mixer to 100 parts by weight of the colored resin fine particle powder to obtain a cyan toner. The obtained cyan toner had a volume-median particle size of 5.0 μm and a softening point of 110 ° C.

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

Comparative Example 1
A resin dispersion was prepared in the same manner as in Example 1 except that 100 g of water was used instead of the nonionic surfactant.
However, the addition of water used instead of the nonionic surfactant and the addition of an aqueous sodium hydroxide solution (concentration: 5% by weight) made it difficult to stir when the system temperature dropped to around 110 ° C. Dispersion could not be prepared.

Comparative Example 2
Resin A and methyl ethyl ketone were mixed with a despar, and the solid content was adjusted to 55% by weight to prepare a resin solution. However, resin A remained as an insoluble material, and a resin dispersion using an organic solvent was prepared. I couldn't.

  The toner obtained by the present invention is suitably used for developing a latent image formed by, for example, 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 in the presence of a nonionic surfactant, a temperature range of 10 ° C above and below the cloud point of the nonionic surfactant, respectively. A method for producing a toner for electrophotography, comprising the step of atomizing the binder resin in an aqueous medium to a volume-median particle size (D ₅₀ ) of 0.05 to 3 μm.   2. The method for producing an electrophotographic toner according to claim 1, wherein the nonionic surfactant has an HLB of 12 to 18.   3. The method for producing an electrophotographic toner according to claim 1, wherein the amount of the nonionic surfactant used is 5 parts by weight or more with respect to 100 parts by weight of the binder resin. Further, the atomized binder resin is at least in the formula (I) and (II):
_{(I) Ts-100 <T} 1 <Ts-5
(II) T ₁ <T ₂ ≦ T ₁ +20
(In the formula, Ts represents the softening point (° C.) of the binder resin)
At T ₁ ° C. and T ₂ ° C. to satisfy, claims 1 to 3 or electrophotographic method for producing a toner according to a step of holding each 30-180 minutes. The method for producing an electrophotographic toner according to claim 4, wherein the volume median particle size (D ₅₀ ) of the aggregated particles generated at the end of holding at T ₁ ° C. is ₁ to 6 μm. The electron according to claim 4 or 5, wherein when the atomized binder resin is heated in an aqueous medium, the binder resin is in a temperature range of 30 ° C to T ₂ ° C for 1 to 8 hours. A method for producing a photographic toner.   The method for producing an electrophotographic toner according to claim 1, wherein the binder resin contains a crystalline polyester having a melting point of 60 to 150 ° C. and a crystallinity index of 0.6 to 1.5.   The method for producing an electrophotographic toner according to claim 1, wherein the cloud point of the nonionic surfactant is 70 to 105 ° C.   The electrophotographic toner according to claim 1, wherein the softening point (Ts) of the binder resin and the cloud point (Tc) of the nonionic surfactant are in a relationship of Ts−30 <Tc <Ts. Production method. A toner for electrophotography obtained by the method of claims 1-9, wherein any one, and also contains a crystalline polyester or 60% by weight of the toner, a volume-median particle size (D ₅₀₎ 1~7μm An electrophotographic toner.