JP5982236B2 - Method for producing toner for electrophotography - Google Patents

Description

  The present invention relates to a method for producing an electrophotographic toner and an electrophotographic toner obtained thereby.

In the field of electrophotographic toner, with development of an electrophotographic system, development of a toner corresponding to high image quality and high speed is required.
In order to achieve high image quality, it has been proposed to control the particle size distribution or reduce the particle size. As a method for realizing this, fine resin particles are aggregated and fused in an aqueous medium. Toner is obtained by the coagulation fusion method (aggregation coalescence method).

  Conventionally, in the production of a toner having a small particle diameter by a chemical method such as a cohesive fusion method, it is known to use a polyester resin having an acid group from the viewpoint of low-temperature fixability of the toner. The resin particle dispersion can be obtained by neutralization with a basic compound. For example, Patent Document 1 discloses that a resin having an acid group is obtained in a basic aqueous medium at a temperature lower than the softening point of the resin in order to obtain an electrophotographic toner without using an organic solvent or a special device. A step of dispersing, a step of neutralizing the obtained dispersion at a temperature above the glass transition temperature of the resin and below the softening point, and an aqueous liquid at a temperature above the glass transition temperature of the resin and below the softening point of the neutralized dispersion. And a step of emulsifying the resin in an aqueous medium and a step of aggregating and fusing the emulsified particles in the obtained resin emulsion in the presence of a colorant. It is disclosed.

JP 2007-106906 A

In the toner by the emulsion aggregation method, the polyester is emulsified in an aqueous medium, and the resulting emulsified particles are agglomerated and fused. In order to finely emulsify the polyester resin in the aqueous medium, the hydrophilicity of the resin From the need to increase the properties, those having a high acid value of the resin are used. However, a toner produced from a resin having a high acid value has a problem of being poor in heat-resistant storage stability due to its high hydrophilicity, which easily absorbs and aggregates moisture.
An object of the present invention is to provide a method for producing an electrophotographic toner that can stably emulsify a polyester resin having a low acid value in an aqueous medium and is excellent in heat-resistant storage stability.

  When emulsifying a polyester resin having a low acid value, the present inventors can stably emulsify by mixing an aliphatic carboxylic acid having a specific carbon number, and are excellent in heat-resistant storage stability. It was found that a toner for use was obtained.

That is, the present invention provides the following [1] and [2].
[1] A method for producing an electrophotographic toner comprising the following steps (1) to (3):
Step (1): A polyester resin having an acid value of 1 to 20 mgKOH / g, a nonionic surfactant, an ionic surfactant, and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms are mixed in an aqueous medium. Step of obtaining a dispersion of resin particles (A) Step (2): The dispersion of resin particles (A) obtained in step (1), the release agent particles and the flocculant are mixed in an aqueous medium for aggregation. Step of obtaining the aggregated particles (1) Step (3): The resin particles (B) are added to the aggregated particles (1) obtained in the step (2) to cause aggregation and fusion. Step [2] An electrophotographic toner obtained by the production method according to [1].

  ADVANTAGE OF THE INVENTION According to this invention, the polyester resin with a low acid value can be stably emulsified in an aqueous medium, and the manufacturing method of the electrophotographic toner which is excellent in heat-resistant storage stability can be provided.

The method for producing the electrophotographic toner of the present invention includes:
Step (1): A polyester resin having an acid value of 1 to 20 mgKOH / g, a nonionic surfactant, an ionic surfactant, and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms are mixed in an aqueous medium. And obtaining a dispersion of resin particles (A),
Step (2): A step of obtaining the aggregated particles (1) by mixing and aggregating the dispersion of the resin particles (A) obtained in the step (1), the release agent particles and the aggregating agent in an aqueous medium, and (3): A step of adding the resin particles (B) to the aggregated particles (1) obtained in the step (2) to cause aggregation and fusion to obtain fused particles.

The detailed reason why the production method of the present invention can produce a toner for electrophotography that can stably emulsify a polyester resin having a low acid value in an aqueous medium and is excellent in heat-resistant storage stability is not clear, but is considered as follows. .
Aliphatic carboxylic acids having a specific number of carbons, when mixed with a polyester resin in an aqueous medium, are incorporated into the polyester resin because they are more hydrophobic than the surfactant and act to complement the hydrophilicity of the resin. . Thereby, it is thought that emulsification of the polyester resin is stabilized.
The toner produced using the thus obtained dispersion of polyester resin particles having a low acid value has low hydrophilicity of the resin, so that moisture absorption during storage is suppressed. As a result, it is considered that the plasticization of the resin by water and the aggregation of the toner particles via water are suppressed, and the heat resistant storage stability is improved.
Hereinafter, each component and process used in the present invention will be described.

<Step (1)>
Step (1) in the method for producing an electrophotographic toner of the present invention comprises a polyester resin having an acid value of 1 to 20 mgKOH / g, a nonionic surfactant, an ionic surfactant, and 1 having 12 to 26 carbon atoms. In this step, a monovalent aliphatic carboxylic acid is mixed in an aqueous medium to obtain a dispersion of resin particles (A).

(Polyester resin)
As the polyester resin, a polyester resin having an acid group is preferably used, and from the viewpoint of improving the emulsifiability of the resin, a polyester resin having an acid group at the molecular chain terminal is more preferable. Examples of the acid group include a carboxy group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid group. Among these, a carboxy group is preferable from the viewpoint of improving the emulsifiability of the resin and improving the heat resistant storage stability of the obtained toner.
In the present invention, the amount of the acid group at the molecular chain terminal of the polyester resin, that is, the acid value of the polyester resin is 1 to 20 mgKOH / g from the viewpoint of improving the emulsifiability of the resin and improving the heat-resistant storage stability of the toner. Preferably 2 mgKOH / g or more, more preferably 3 mgKOH / g or more, further preferably 5 mgKOH / g or more, preferably 18 mgKOH / g or less, more preferably 15 mgKOH / g or less, still more preferably 12 mgKOH / g or less. More preferably, it is less than 10 mgKOH / g, and still more preferably 9 mgKOH / g or less. In addition, when a some polyester resin is included, the acid value of the whole resin should just be in the said range. An acid value is measured by the method as described in an Example.

  The content of the polyester resin in the resin particles (A) is preferably 80% by mass or more, more preferably 90% by mass or more, from the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability. 95 mass% or more is still more preferable, substantially 100 mass% is still more preferable, and 100 mass% is still more preferable.

The raw material monomer of the polyester resin is not particularly limited, and an arbitrary alcohol component and an arbitrary carboxylic acid component such as carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.
Examples of the acid component include dicarboxylic acids, trivalent or higher polyvalent carboxylic acids, acid anhydrides thereof, and alkyl esters having 1 to 3 carbon atoms. Among them, dicarboxylic acids are preferable.
Specific examples of the dicarboxylic acid include aromatic dicarboxylic acid and aliphatic dicarboxylic acid. Examples of the aromatic dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. As aliphatic dicarboxylic acid, it was substituted with sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, cyclohexanedicarboxylic acid, alkyl group having 1 to 20 carbon atoms or alkenyl group having 2 to 20 carbon atoms. Examples include aliphatic dicarboxylic acids such as succinic acid. Of these, fumaric acid, terephthalic acid and dodecenyl succinic acid are preferred.
Specific examples of the trivalent or higher polyvalent carboxylic acids include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and the like. Among them, the heat resistant storage stability and high temperature offset resistance of the toner are improved. Therefore, trimellitic acid and its acid anhydride are preferable.
An acid component can be used individually or in combination of 2 or more types.

Examples of the alcohol component include aliphatic diols having 2 to 12 carbon atoms in the main chain, aromatic diols, hydrogenated products of bisphenol A, trihydric or higher polyhydric alcohols, and the like.
Preferred examples of the alcohol component include 2 carbon atoms of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane. Aromatic diols such as adducts of 3 to 3 alkylene oxides (average number of added moles of 1 to 16), alicyclic diols such as hydrogenated bisphenol A, or alkylene oxides of 2 to 4 carbon atoms thereof (average number of added moles of 1) -16) Adducts, aliphatic diols such as ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol or those having 2 to 4 carbon atoms Alkylene oxide (average addition mole number 1-16) adduct, glycerin, pentaerythrine Lithol, trimethylolpropane, aliphatic polyhydric alcohols or their alkylene oxide having 2 to 4 carbon atoms such as sorbitol (average addition molar number of 1 to 16) adduct, and the like. You may use the said alcohol component in combination of 2 or more type. Examples of the alcohol component include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, and the like from the viewpoint of improving the heat resistant storage stability of the toner. The adduct of bisphenol A having 2 to 3 carbon atoms of alkylene oxide (average added mole number of 1 to 16) is preferred.

The polyester can be produced, for example, by polycondensing the alcohol component and the carboxylic acid component at a temperature of about 120 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst. it can.
As the esterification catalyst, an esterification catalyst such as a tin compound such as dibutyltin oxide or di (2-ethylhexanoic acid) tin or a titanium compound such as titanium diisopropylate bistriethanolamate can be used.
Although there is no restriction | limiting in the usage-amount of an esterification catalyst, 0.01-1 mass part is preferable with respect to 100 mass parts of total amounts of an acid component and an alcohol component, and 0.1-0.6 mass part is more preferable.
Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 to 0.5 parts by mass and more preferably 0.005 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the acid component and the alcohol component.

As the polyester resin in the resin particles (A), either crystalline polyester or amorphous polyester can be used, and both can be mixed and used, but in the present invention, the heat resistant storage stability of the toner is improved. From the viewpoint of making it, it is preferable to contain an amorphous polyester. 80-100 mass% is preferable, as for content of the amorphous polyester in the polyester resin in the resin particle (A), 90-100 mass% is more preferable, 95-100 mass% is still more preferable, and substantially 100 mass. % Is more preferable, and 100% by mass is even more preferable.
When the crystalline polyester and the amorphous polyester are used in combination, the mass ratio of the crystalline polyester to the amorphous polyester (crystalline polyester / amorphous polyester) is selected from the viewpoint of improving the low-temperature fixability of the toner. From the viewpoint of improving the storage stability and improving the high temperature offset resistance, the ratio is preferably 5/95 to 50/50, and more preferably 10/90 to 20/80.

  Here, the crystallinity of the resin is defined by the ratio between the softening point and the maximum endothermic peak temperature measured by a differential scanning calorimeter (DSC), that is, (softening point (° C)) / (maximum endothermic peak temperature (° C)). Expressed by the crystallinity index. The crystalline resin has a crystallinity index of 0.6 to 1.4, preferably 0.8 to 1.3, and more preferably 0.9 to 1.2. The amorphous resin is a resin having a crystallinity index of more than 1.4 or less than 0.6, and from the viewpoint of improving the low-temperature fixability of the toner and improving heat-resistant storage stability, it is less than 0.6 or It is preferably more than 1.4 and 4 or less, more preferably less than 0.6 or 1.5 or more and 4 or less, still more preferably less than 0.6 or 1.5 or more and 3 or less, and still more preferably 0.6. Less than or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined according to the production conditions such as the type and ratio of the raw material monomers, the reaction temperature, the reaction time, and the cooling rate. The maximum endothermic peak temperature refers to the temperature of the peak on the highest temperature side among the observed endothermic peaks. The maximum peak temperature is the melting point if the difference from the softening point is within 20 ° C., and the peak due to the glass transition if the difference from the softening point exceeds 20 ° C.

  The softening point of the polyester resin is preferably from 70 to 165 ° C, more preferably from 80 to 140 ° C, still more preferably from 90 to 130 ° C, from the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability. -120 degreeC is still more preferable.

  The glass transition temperature of the polyester resin is preferably 50 to 80 ° C., more preferably 55 to 70 ° C., and still more preferably 58 to 67 ° C. from the viewpoint of improving the low-temperature fixability of the toner and the heat-resistant storage stability. The glass transition temperature is a physical property unique to an amorphous resin.

  In the present invention, the polyester resin includes not only an unmodified polyester as long as it has an acid group, but also a polyester modified to such an extent that the properties are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of resin units including a polyester unit.

When the resin particle (A) contains a plurality of resins including a polyester resin having an acid group, the softening point, glass transition temperature, and acid value of the resin constituting the resin particle (A) are as follows. Means a softening point, a glass transition temperature, and an acid value as a mixture, and each value is preferably within the range of each characteristic of the polyester resin. The softening point, glass transition temperature, and acid value as a mixture can be determined by weighted average of the values, that is, the sum of the product of the characteristic value and the content ratio of each resin.
Further, when the polyester resin is contained, the resin constituting the resin particle (A) can contain two kinds of polyester resins having different softening points, and the viewpoint of improving the low-temperature fixability of the toner, the heat resistant storage stability. From the viewpoint of improving and improving the high temperature offset resistance, the softening point of one polyester (I) is preferably 70 ° C. or higher and lower than 115 ° C., and the softening point of the other polyester (II) is 115 ° C. or higher and 165 ° C. or lower. preferable. The difference in softening point between the two types of polyester resins is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, more preferably 30 ° C. or lower, and more preferably 20 ° C. or lower from the same viewpoint. The mass ratio (I / II) between the polyester (I) and the polyester (II) is preferably 10/90 to 90/10 from the viewpoint of improving the low-temperature fixability of the toner and the heat-resistant storage stability of the toner. 50/50 to 80/20 is more preferable, and 60/40 to 70/30 is still more preferable.

  In the production of the resin particles (A), as long as the effect of the present invention is not impaired, a resin other than a polyester resin, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, a polyurethane, You may make resin particle (A) contain these resins.

(Surfactant)
In the present invention, from the viewpoint of improving the emulsifiability of the resin, a nonionic surfactant and an ionic surfactant are used in combination. Examples of the ionic surfactant include an anionic surfactant and a cationic surfactant. In the present invention, it is preferable to use a nonionic surfactant and an anionic surfactant in combination from the viewpoint of improving the emulsifiability of the resin.
The mass ratio of the nonionic surfactant to the ionic surfactant (nonionic surfactant / ionic surfactant) is preferably from 0.3 to 10 from the viewpoint of improving the emulsifiability of the resin, 0.5-5 is more preferable and 0.8-1.5 is still more preferable.
When a nonionic surfactant and an anionic surfactant are used in combination, the mass ratio of the nonionic surfactant to the anionic surfactant (nonionic surfactant / anionic surfactant) is: From the viewpoint of improving the emulsifiability of the resin, 0.3 to 10 is preferable, 0.5 to 5 is more preferable, and 0.8 to 1.5 is still more preferable.

The nonionic surfactant is preferably at least one selected from the group consisting of polyoxyethylene alkyl aryl ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, and oxyethylene / oxypropylene block copolymers.
Specific examples of polyoxyethylene alkyl aryl ethers include polyoxyethylene nonylphenyl ether, and specific examples of polyoxyethylene alkyl ethers include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and the like. It is done. Specific examples of polyoxyethylene fatty acid esters include polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, and the like.
As the nonionic surfactant, polyoxyethylene alkyl ethers are preferable from the viewpoint of improving the emulsifiability of the resin, and among them, polyoxyethylene oleyl ether is preferable.

The anionic surfactant is preferably at least one selected from the group consisting of alkylbenzene sulfonates, alkyl sulfates, and alkyl ether sulfates. As a kind of salt, at least 1 sort (s) chosen from the group which consists of sodium salt, potassium salt, and ammonium salt is preferable.
The anionic surfactant is preferably at least one selected from the group consisting of sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and sodium dodecylethersulfate from the viewpoint of improving the emulsifiability of the resin, and sodium dodecylbenzenesulfonate is preferable. More preferred.
Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, dialkyl ammonium chloride and the like.

  Among these, from the viewpoint of improving the emulsifiability of the resin, it is preferable to use polyoxyethylene alkyl ethers and alkylbenzene sulfonate together, and it is more preferable to use polyoxyethylene oleyl ether and sodium dodecylbenzene sulfonate together. preferable.

  The addition amount of the nonionic surfactant is preferably 10 parts by mass or less, and 7.5 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (A) from the viewpoint of improving the heat resistant storage stability of the toner. The following is more preferable, 5 parts by mass or less is further preferable, and 2.5 parts by mass or less is further more preferable. Moreover, from a viewpoint of improving the emulsifiability of resin, 0.05 mass part or more is preferable with respect to 100 mass parts of resin which comprises resin particle (A), 0.25 mass part or more is more preferable, 0.5 More preferred is part by mass or more.

  The addition amount of the ionic surfactant is preferably 10 parts by mass or less, and 7.5 parts by mass or less with respect to 100 parts by mass of the resin constituting the resin particles (A) from the viewpoint of improving the heat-resistant storage stability of the toner. Is more preferable, 5 mass parts or less are still more preferable, and 2.5 mass parts or less are still more preferable. Moreover, from a viewpoint of improving the emulsifiability of resin, 0.05 mass part or more is preferable with respect to 100 mass parts of resin which comprises resin particle (A), 0.25 mass part or more is more preferable, 0.5 More preferred is part by mass or more.

  The total addition amount of the nonionic surfactant and the ionic surfactant is 20 parts by mass or less with respect to 100 parts by mass of the resin constituting the resin particles (A) from the viewpoint of improving the heat resistant storage stability of the toner. Is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5 parts by mass or less. Moreover, from a viewpoint of improving the emulsifiability of resin, 0.1 mass part or more is preferable with respect to 100 mass parts of resin which comprises resin particle (A), 0.5 mass part or more is more preferable, 1 mass part The above is more preferable.

(Monovalent aliphatic carboxylic acid)
A monovalent aliphatic carboxylic acid is used from the viewpoint of stably emulsifying a polyester resin having a low acid value in an aqueous medium and improving the heat-resistant storage stability of the obtained toner. Here, the “aliphatic carboxylic acid” in the present invention includes not only a free acid but also an anhydride that decomposes during the reaction to produce an acid and an alkyl ester having 1 to 3 carbon atoms. Is not included. As mentioned above, aliphatic carboxylic acids having a specific number of carbons are incorporated in polyester resins because they are more hydrophobic than surfactants when mixed with polyester resins in an aqueous medium, complementing the hydrophilicity of the resin. Thus, it is considered that the emulsification of the polyester resin is stabilized. On the other hand, the metal salt of aliphatic carboxylic acid is hydrophilic and acts only as a surfactant so that it is not taken into the polyester resin, and it is considered that polyester having a low acid value cannot be stably emulsified. .

The number of carbon atoms of the monovalent aliphatic carboxylic acid is 12 to 26, preferably 12 to 22, more preferably 14 to 18, and still more preferably 16 to 18 from the viewpoint of improving the emulsifiability of the resin. Further, it may be a linear aliphatic carboxylic acid or a branched aliphatic carboxylic acid.
Examples of the monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms include saturated aliphatic carboxylic acids and unsaturated aliphatic carboxylic acids.
Specific examples of the monovalent saturated aliphatic carboxylic acid having 12 to 26 carbon atoms include lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, Examples include lignoceric acid, serotic acid, isopalmitic acid, isostearic acid and the like.
Specific examples of the monovalent unsaturated aliphatic carboxylic acid having 12 to 26 carbon atoms include Linderic acid, Tsuzic acid, Myristoleic acid, Palmitoleic acid, Oleic acid, Linoleic acid, Linolenic acid, Arachidonic acid and the like. .
The monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms is preferably a saturated aliphatic carboxylic acid from the viewpoint of improving the heat-resistant storage stability of the toner, and lauric acid, myristic acid, from the viewpoint of improving the emulsifiability of the resin. At least one selected from the group consisting of palmitic acid, stearic acid and behenic acid is more preferable, at least one selected from the group consisting of palmitic acid and stearic acid is more preferable, and stearic acid is still more preferable.

  The addition amount of the monovalent aliphatic carboxylic acid is preferably 10 parts by mass or less, preferably 5 parts by mass or less with respect to 100 parts by mass of the resin constituting the resin particles (A), from the viewpoint of improving the heat resistant storage stability of the toner. Is more preferable, 4 mass parts or less are still more preferable, and 3 mass parts or less are still more preferable. Moreover, from a viewpoint of improving the emulsifiability of resin, 0.1 mass part or more is preferable, 0.3 mass part or more is more preferable, 0.5 mass part or more is further more preferable, and 0.8 mass part or more is still more preferable. preferable.

  The total addition amount of the monovalent aliphatic carboxylic acid and the surfactant (nonionic surfactant and ionic surfactant) constitutes the resin particles (A) from the viewpoint of improving the heat resistant storage stability of the toner. 30 mass parts or less are preferable with respect to 100 mass parts of resin to perform, 20 mass parts or less are more preferable, 15 mass parts or less are still more preferable, and 10 mass parts or less are still more preferable. Moreover, from a viewpoint of improving the emulsifiability of resin, 0.2 mass part or more is preferable, 0.5 mass part or more is more preferable, 0.8 mass part or more is further more preferable, 1.0 mass part or more is still more preferable. preferable.

  The ratio of the addition amount of monovalent aliphatic carboxylic acid to the addition amount of surfactant (nonionic surfactant and ionic surfactant) (monovalent aliphatic carboxylic acid / surfactant) is From the viewpoint of improving the heat resistant storage stability, 10/90 to 90/10 is preferable, 20/80 to 70/30 is more preferable, 25/75 to 60/40 is further preferable, and 30/70 to 55/45 is more preferable. Further preferred.

  In the production of the resin particles (A), a colorant, a release agent, and a charge control agent may be contained within a range that does not impair the effects of the present invention. Moreover, you may contain additives, such as reinforcement fillers, such as a fibrous material, antioxidant, and anti-aging agent, as needed.

(Coloring agent)
The resin particles (A) may be particles made of resin alone, or may be colorant-containing resin particles containing a colorant, but contain a colorant from the viewpoint of sharpening the particle size distribution of the toner. It is preferable to be a colorant-containing resin particle containing a colorant.
When obtaining the resin particles (A) which are colorant-containing resin particles, the amount of the colorant added is the resin constituting the resin particles (A) from the viewpoint of improving the image density of the toner and improving the low-temperature fixability. 1 mass part or more is preferable with respect to 100 mass parts, 5 mass parts or more is more preferable, 20 mass parts or less are preferable, and 10 mass parts or less are more preferable.

As the colorant, pigments and dyes are used, and pigments are preferable from the viewpoint of improving the image density of the toner.
Specific examples of the pigment include carbon black, inorganic composite oxide, benzidine yellow, brilliantamine 3B, brilliantamine 6B, Bengal, aniline blue, ultramarine blue, copper phthalocyanine, phthalocyanine green, and the like, with copper phthalocyanine being preferred. .
Specific examples of the dye include acridine series, azo series, benzoquinone series, azine series, anthraquinone series, indico series, phthalocyanine series, and aniline black series.
A coloring agent can be used individually by 1 type or in combination of 2 or more types.

(Production of resin particles (A))
The resin particles (A) are obtained by mixing the above-mentioned optional components such as a polyester resin, a surfactant, a monovalent aliphatic carboxylic acid, and a colorant in an aqueous medium to obtain a dispersion of the resin particles (A). Manufactured by.

The aqueous medium preferably contains water as a main component. From the viewpoint of environmental properties and the viewpoint of improving the heat resistant storage stability of the toner, the content of water in the aqueous medium is preferably 80% by mass or more, and 90% by mass or more. Is more preferable, 95 mass% or more is still more preferable, substantially 100 mass% is still more preferable, and 100 mass% is still more preferable. As water, deionized water or distilled water is preferably used.
As components other than water, organic solvents that dissolve in water such as alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having 1 to 3 carbon atoms such as acetone and methyl ethyl ketone; and cyclic ethers such as tetrahydrofuran are used. Among these, from the viewpoint of preventing the organic solvent from being mixed into the toner, an alkyl alcohol having 1 to 5 carbon atoms that does not dissolve the polyester resin is preferable, and methanol, ethanol, isopropanol, and butanol are more preferable.

  As a method for obtaining a dispersion containing the resin particles (A), a method of adding a resin or the like to an aqueous medium and performing a dispersion treatment with a disperser or the like, or an aqueous medium is gradually added to the resin or the like to perform phase inversion emulsification. From the viewpoint of improving the low-temperature fixability of the obtained toner, a method using phase inversion emulsification is preferable. Hereinafter, a method by phase inversion emulsification will be described.

First, the above-mentioned optional components such as a polyester resin, a surfactant, a monovalent aliphatic carboxylic acid, and a colorant are melted and mixed to obtain a resin mixture.
When the polyester resin is composed of a plurality of resins, a mixture of polyester and other resins may be used in advance, but when other components are added, they are added simultaneously and melted and mixed. A resin mixture may be obtained.

  As a method for obtaining a resin mixture, the above optional components such as polyester resin, surfactant, monovalent aliphatic carboxylic acid, and coloring agent are put in a container and mixed in an aqueous medium, and then an aqueous alkali solution is added and stirred. A method in which the resin is melted and mixed uniformly while stirring with a vessel is preferred.

  Examples of the alkali in the alkaline aqueous solution include hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide, and ammonia. From the viewpoint of improving the emulsifiability of the resin, potassium hydroxide and sodium hydroxide may be used. preferable. Further, the alkali concentration in the alkaline aqueous solution is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, more preferably 1% by mass or more, and more preferably 1.5% by mass or more. More preferred is 2% by mass or more.

  The temperature at which the resin is melted and mixed is preferably equal to or higher than the glass transition temperature of the polyester resin from the viewpoint of obtaining homogeneous resin particles, and more preferably equal to or higher than the melting point when crystalline polyester is included.

  Next, an aqueous medium is added to the resin mixture and phase inversion is performed to obtain a dispersion containing resin particles (A).

  From the viewpoint of obtaining homogeneous resin particles, the temperature at which the aqueous medium is added is preferably not less than the glass transition temperature of the polyester resin, and more preferably not less than the melting point when the crystalline polyester is included.

  The addition rate of the aqueous medium is preferably 50 parts by mass or less per 100 parts by mass of the resin constituting the resin particles (A) until the phase inversion is completed from the viewpoint of making the resin particles small. , 30 parts by mass or less is more preferable, 10 parts by mass or less is more preferable, 5 parts by mass or less is more preferable, 0.1 parts by mass or more is preferable, and 0.5 parts by mass is preferable. / Min or more is more preferable. There is no restriction | limiting in the addition speed | rate of the aqueous medium after the resin phase is obtained after phase inversion.

  The amount of the aqueous medium used is preferably 900 parts by mass or less and more preferably 500 parts by mass or less with respect to 100 parts by mass of the resin constituting the resin particles (A) from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step. Preferably, 300 parts by mass or less is more preferable, 100 parts by mass or more is preferable, 150 parts by mass or more is more preferable, and 170 parts by mass or more is further preferable.

  The solid content concentration of the obtained dispersion of the resin particles (A) is preferably 55% by mass or less from the viewpoint of improving the stability of the resin particle dispersion and facilitating handling. % By mass or less is more preferable, 40% by mass or less is more preferable, 35% by mass or less is more preferable, 10% by mass or more is preferable, 17% by mass or more is more preferable, 20% by mass or more is further preferable, 25 The mass% or more is still more preferable. In addition, solid content is the total amount of non-volatile components, such as resin and surfactant.

The volume median particle size of the resin particles (A) in the dispersion of the obtained resin particles (A) is preferably 2 μm or less, more preferably 1.5 μm or less from the viewpoint of obtaining a high-quality toner. 1 μm or less is more preferable, 0.5 μm or less is more preferable, 0.02 μm or more is preferable, 0.05 μm or more is more preferable, 0.10 μm or more is further preferable, and 0.15 μm or more is more preferable. Further preferred. Here, the volume-median particle size is a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. The volume-median particle diameter is specifically determined by the method described in the examples.
Further, the coefficient of variation (CV value) (%) of the particle size distribution of the resin particles (A) is preferably 40% or less, more preferably 35% or less, and more preferably 30% or less from the viewpoint of obtaining a high-quality toner. Is more preferable. The CV value is a value represented by the following formula, and is specifically obtained by the method described in the examples.
CV value (%) = [standard deviation of particle size distribution (μm) / volume average particle size (μm)] × 100

<Step (2)>
In the step (2) in the method for producing an electrophotographic toner of the present invention, the dispersion of the resin particles (A) obtained in the step (1), the release agent particles and the flocculant are mixed and agglomerated in an aqueous medium. In this step, the aggregated particles (1) are obtained.

[Releasing agent particles]
In the present invention, the release agent particles are preferably obtained as a dispersion of release agent particles by dispersing the release agent in an aqueous medium.

(Release agent)
As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide and stearic acid amide; carnauba wax, rice wax and candelilla wax Plant waxes such as beeswax; animal waxes such as beeswax; mineral / petroleum waxes such as montan wax, paraffin wax, and Fischer-Tropsch wax. These release agents can be used alone or in combination of two or more.
The melting point of the release agent is preferably 100 ° C. or lower, more preferably 95 ° C. or lower, still more preferably 90 ° C. or lower, and 85 ° C. or lower from the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability. More preferably, it is preferably 60 ° C. or higher, more preferably 65 ° C. or higher, still more preferably 70 ° C. or higher, and even more preferably 73 ° C. or higher.
In the present invention, the melting point of the release agent is determined by the method described in the examples. When two or more kinds are used in combination, the melting point of the release agent having the largest mass ratio among the release agents contained in the obtained toner is the melting point of the release agent in the present invention. When all have the same ratio, the lowest value is set.
The amount of the release agent used is based on 100 parts by mass of the resin constituting the resin particles (A) from the viewpoint of improving the releasability of the toner, the viewpoint of improving the low temperature fixability, and the viewpoint of improving the heat resistant storage stability. 20 parts by mass or less, preferably 15 parts by mass or less, more preferably 1 part by mass or more, and more preferably 2 parts by mass or more.

(Manufacture of release agent particles)
The release agent particles are preferably obtained as a dispersion of release agent particles by dispersing the release agent in an aqueous medium. The dispersion of the release agent particles is preferably obtained by dispersing the release agent in an aqueous medium in the presence of a surfactant at a temperature equal to or higher than the melting point of the release agent using a disperser. As the machine, a homogenizer, an ultrasonic disperser or the like is preferable. What is necessary is just to set dispersion | distribution time suitably with the disperser to be used.

  As an aqueous medium, the thing similar to what is used for the manufacturing method of the said resin particle (A) can be used suitably.

The dispersion of the release agent particles in the aqueous medium is preferably performed in the presence of a surfactant from the viewpoint of enabling appropriate aggregation of the resin particles (A) and the release agent particles.
As the surfactant, an anionic surfactant is preferable from the viewpoint of improving the cohesiveness between the release agent particles and the resin particles, and among these, from the same viewpoint, a hydrophilic group is more preferably a carboxy group. Carboxylate is more preferred. Preferable specific examples of the polycarboxylic acid salt to be used include polyacrylic acid salt, acrylic acid-maleic acid copolymer salt, from the viewpoint of improving the cohesiveness and releasing of the releasing agent particles during toner preparation, Polymerate and the like are preferable, and an acrylic acid-maleic acid copolymer salt is more preferable. As the salt, an alkali metal salt is preferable, and a sodium salt is more preferable.
The weight average molecular weight of the polycarboxylate is preferably 90,000 or less, more preferably 50,000 or less, and 3,000 or more from the viewpoint of improving the dispersibility of the release agent particles. Is preferable, and 10,000 or more is more preferable.
As a commercially available product of polycarboxylate, Poise 530 (trade name, sodium polyacrylate aqueous solution, weight average molecular weight 38000, effective concentration 40 mass%) manufactured by Kao Corporation, Poise 521 (trade name, sodium acrylate-maleic acid) Sodium copolymer aqueous solution, weight average molecular weight 20000, effective concentration 40% by mass) and the like.
The content of the surfactant in the release agent dispersion is preferably 5% by mass or less, preferably 2% by mass or less from the viewpoint of improving the cohesiveness of the release agent particles at the time of toner preparation and preventing release. More preferably, 1% by mass or less is further preferable, 0.05% by mass or more is preferable, 0.1% by mass or more is more preferable, and 0.4% by mass or more is further preferable. From the same viewpoint, the content of the surfactant in the release agent dispersion is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, with respect to 100 parts by mass of the total release agent. 0 parts by mass or less is more preferable, 0.2 parts by mass or more is preferable, 1.0 parts by mass or more is more preferable, and 2.0 parts by mass or more is still more preferable.

The volume median particle size of the release agent particles is preferably 1 μm or less, more preferably 0.8 μm or less, and more preferably 0.6 μm or less from the viewpoint of improving the heat-resistant storage stability and high-temperature offset resistance of the obtained toner. Is more preferably 0.1 μm or more, more preferably 0.2 μm or more, and further preferably 0.3 μm or more.
The CV value of the release agent particles is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less from the viewpoint of improving the heat-resistant storage stability and high-temperature offset resistance of the obtained toner. . Further, from the viewpoint of improving the productivity of the release agent particle dispersion, it is preferably 15% or more, more preferably 20% or more, and further preferably 25% or more. The volume-median particle size and CV value of the release agent particles are determined by the same method as that for the resin particles (A), and specifically by the method described in the examples.

  The solid content concentration of the release agent particle dispersion is preferably 50% by mass or less, more preferably 40% by mass or less from the viewpoint of improving the dispersion stability of the release agent particles and facilitating handling. Moreover, 7 mass% or more is preferable and 10 mass% or more is more preferable.

[Production of Aggregated Particles (1)]
The agglomerated particles (1) are obtained by mixing the resin particles (A), release agent particles, aggregating agent, and optional components such as a colorant in an aqueous medium and aggregating them to obtain a dispersion of the agglomerated particles (1). To manufacture.

In this step, first, the resin particles (A) and the release agent particles are mixed in an aqueous medium to obtain a mixed dispersion.
In addition, when a colorant is not mixed with the resin particles (A) in the step (1), it is preferable to mix a colorant in this step.
In this step, resin particles other than the resin particles (A) may be mixed. As resin particles other than resin particles (A), resin particles containing amorphous polyester are preferable, and those having the same composition as resin particles (B) described later are more preferable.
There is no restriction | limiting in order of mixing, You may add any in order and may add simultaneously.

In 100 parts by mass of the mixed dispersion, the resin particles (A) are preferably 40 parts by mass or less, more preferably 30 parts by mass or less, more preferably 10 parts by mass or more, and more preferably 20 parts by mass or more. The aqueous medium is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and preferably 60 parts by mass or more, and more preferably 65 parts by mass or more.
From the viewpoint of improving the releasability of the toner, the viewpoint of suppressing the scattering of the toner, and the viewpoint of improving the heat resistant storage stability, the release agent particles are 20 masses per 100 mass parts of the resin constituting the resin particles (A). Part or less, preferably 15 parts by weight or less, more preferably 1 part by weight or more, and more preferably 2 parts by weight or more.
Moreover, when mixing a coloring agent at this process, content of a coloring agent is 20 mass parts or less with respect to 100 mass parts of resin which comprises resin particle (A) from a viewpoint of improving the image density of a toner. Preferably, 10 parts by mass or less is more preferable, 1 part by mass or more is preferable, and 5 parts by mass or more is more preferable.
The mixing temperature is preferably 0 to 40 ° C. from the viewpoint of aggregation control.

Next, the particles in the mixed dispersion can be aggregated to suitably obtain a dispersion of aggregated particles (1). A flocculant is added for efficient aggregation.
As the flocculant, an inorganic flocculant such as a cationic surfactant of a quaternary salt, an organic flocculant such as polyethyleneimine, an inorganic metal salt, an inorganic ammonium salt, or a bivalent or higher metal complex is used.
Examples of the inorganic metal salt include metal salts such as sodium sulfate, sodium chloride, calcium chloride, magnesium sulfate, and calcium nitrate, and inorganic metal salt polymers such as polyaluminum chloride and polyaluminum hydroxide. Examples of inorganic ammonium salts include ammonium sulfate, ammonium chloride, and ammonium nitrate. The flocculant is preferably an inorganic ammonium salt and more preferably ammonium sulfate from the viewpoint of improving the flocculence and obtaining uniform agglomerated particles.
From the viewpoint of improving the heat resistant storage stability of the toner, the amount of the flocculant used is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, with respect to 100 parts by mass of the resin constituting the resin particles (A). The part by mass or less is more preferable. Further, from the viewpoint of improving the cohesiveness of the resin particles (A), 1 part by mass or more is preferable, 5 parts by mass or more is more preferable, and 10 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (A). The above is more preferable. From these viewpoints, the use amount of the flocculant is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight, and more preferably 10 to 35 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A). Is more preferable.

  As an aggregating method, an aggregating agent is preferably added dropwise as an aqueous solution to a container containing a mixed dispersion. The flocculant may be added at one time, or may be added intermittently or continuously. However, it is preferable to perform sufficient stirring at the time of addition and after completion of the addition. From the viewpoint of controlling aggregation and shortening the toner production time, the dropping time of the aggregating agent is preferably 1 to 120 minutes. The dropping temperature is preferably 0 to 50 ° C. from the viewpoint of controlling aggregation.

  At the time of agglomeration, from the viewpoint of controlling the particle size of the agglomerated particles and suppressing the formation of coarse particles, the temperature in the agglomerated system is 25 ° C. or lower than the glass transition temperature of the resin constituting the resin particles (A) The temperature is preferably 25 ° C. or more and 15 ° C. or less higher than the glass transition temperature, more preferably 35 ° C. or more and 5 ° C. or less higher than the glass transition temperature. It is preferable to confirm the progress of aggregation by monitoring the volume-median particle size of the aggregated particles in the temperature range. The volume median particle size is measured by the method described in the examples.

  The volume median particle size of the obtained aggregated particles (1) is preferably 1 to 10 μm, more preferably 2 to 9 μm, and more preferably 3 to 6 μm from the viewpoint of reducing the toner particle size and suppressing toner scattering. Is more preferable. Further, the CV value is preferably 30% or less, more preferably 28% or less, and further preferably 25% or less. The volume-median particle size and CV value of the aggregated particles (1) are specifically determined by the method described in the examples.

<Step (3)>
Step (3) is a step of adding the resin particles (B) to the agglomerated particles (1) obtained in the step (2) and aggregating and fusing them to obtain fused particles.
In this step, the dispersion of resin particles (B) is added to the dispersion of aggregated particles (1) obtained in step (2), and the resin particles (B) are further adhered to the aggregated particles (1). It is preferable to obtain aggregated particles (2) and then fuse the particles constituting the aggregated particles (2) to obtain fused particles.

[Resin particles (B)]
In the present invention, the resin particles (B) preferably contain a polyester resin from the viewpoint of improving the low-temperature fixability of the toner and the heat-resistant storage stability.

The resin particles (B) preferably contain 70% by mass or more, more preferably 80% by mass or more, and 90% by mass from the viewpoint of improving low-temperature fixability of the toner and improving heat-resistant storage stability. The above is further preferable, 95% by mass or more is further preferable, the content is substantially preferably 100% by mass, and further preferably 100% by mass.
As the polyester resin that can be contained in the resin particles (B), the same polyester resin as that that can be contained in the resin particles (A) can be suitably used. A resin having the same composition as the polyester resin that can be contained in the resin particles (A) may be used, or a resin having a different composition may be used.
The resin particles (B) may further contain a known resin usually used for toner, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, and a polyurethane, together with the polyester resin.

Similarly to the resin particles (A) described above, the resin particles (B) may contain a colorant, a release agent, and a charge control agent as long as the effects of the present invention are not impaired. Moreover, you may contain additives, such as reinforcing fillers, such as a fibrous material, antioxidant, and anti-aging agent, as needed.
The resin particles (B) are preferably obtained as a dispersion of the resin particles (B) by the same method as the method for producing the resin particles (A) described above. The alkaline aqueous solution, surfactant, and aqueous medium used are also resins. The thing similar to the manufacturing method of particle | grains (A) can be used suitably. Resin particles (A) can also be used as resin particles (B).

From the viewpoint of obtaining a high-quality toner, the volume median particle size of the resin particles (B) in the dispersion of the resin particles (B) is preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm or less. 0.5 μm or less is more preferable, 0.02 μm or more is preferable, 0.05 μm or more is more preferable, 0.1 μm or more is further preferable, and 0.15 μm or more is even more preferable.
In addition, the coefficient of variation (CV value) (%) of the particle size distribution of the resin particles (B) is preferably 40% or less, more preferably 35% or less, and more preferably 30% or less from the viewpoint of obtaining a high-quality toner. Is more preferable. The volume median particle size and CV value of the resin particles (B) are determined by the same method as that for the resin particles (A), and specifically by the method described in the examples.

  The solid content concentration of the dispersion of the resin particles (B) is preferably 55% by mass or less and 45% by mass or less from the viewpoint of improving the stability of the obtained resin particle dispersion and facilitating handling. More preferably, 40% by mass is further preferable, 35% by mass or less is more preferable, 10% by mass or more is preferable, 17% by mass or more is more preferable, 20% by mass or more is further preferable, and 25% by mass or more is more preferable. Further preferred.

[Production of Aggregated Particles (2)]
Aggregated particles (2) are obtained by adding a dispersion of resin particles (B) to the dispersion of aggregated particles (1) obtained in step (2), and further adding resin particles (B) to aggregated particles (1). To produce a dispersion of aggregated particles (2).

Before and / or simultaneously with the addition of the dispersion containing resin particles (B) (dispersion of resin particles (B)) to the dispersion containing aggregated particles (1) (dispersion of aggregated particles (1)). Alternatively, an aqueous medium may be added to the dispersion of aggregated particles (1) for dilution. It is preferable to add an aqueous medium, and it is more preferable to add it simultaneously with the dispersion of the resin particles (B). By adding the aqueous medium, the resin particles (B) can be more uniformly attached to the aggregated particles (1).
When the dispersion liquid of the resin particles (B) is added to the dispersion liquid of the aggregated particles (1), the aggregating agent may be used for efficiently attaching the resin particles (B) to the aggregated particles (1). .
As a preferable addition method in the case of adding the dispersion liquid of the resin particles (B) to the dispersion liquid of the aggregated particles (1), a method of simultaneously adding the aggregation liquid and the dispersion liquid of the resin particles (B), the aggregating agent and the resin Examples thereof include a method of alternately adding a dispersion of particles (B) and a method of adding a dispersion of resin particles (B) while gradually increasing the temperature of the dispersion of aggregated particles (1). By doing in this way, the cohesiveness fall of the aggregated particle (1) and the resin particle (B) by the coagulant | flocculant density | concentration fall can be prevented. From the viewpoint of improving the productivity of the toner and simplifying the production, it is preferable to add the dispersion of the resin particles (B) while gradually increasing the temperature of the dispersion of the aggregated particles (1).

  The temperature in the system in this step is the melting point when crystalline polyester is contained in the resin constituting the resin particles (A) from the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability. It is preferably 5 ° C. or more lower than the glass transition temperature of the resin constituting the resin particles (B), more preferably 5 ° C. or more. When the aggregated particles (2) are produced in this temperature range, the low-temperature fixability and heat-resistant storage stability of the obtained toner are improved. Although the reason is not certain, it is considered that the generation of coarse particles is suppressed because fusion of the aggregated particles (2) does not occur.

  The addition amount of the resin particles (B) is such that the resin particles (B) and the resin particles (A) are added from the viewpoints of improving the low temperature fixability of the toner, improving the heat resistant storage stability, and improving the high temperature offset resistance. Mass ratio (resin particle (B) / resin particle (A)) is preferably 1.5 or less, more preferably 1.0 or less, still more preferably 0.5 or less, and preferably 0.1 or more, 0.2 or more is more preferable, and 0.25 or more is still more preferable.

  The dispersion of the resin particles (B) may be added continuously over a certain period of time, may be added at a time, or may be added in multiple portions. It is preferable to add continuously over several times or to divide and add several times. By adding as described above, the resin particles (B) are likely to selectively adhere to the aggregated particles (1). Among these, it is preferable to add continuously over a certain time from the viewpoint of promoting selective adhesion and improving the efficiency of toner production. The time for continuous addition is preferably 1 to 10 hours, more preferably 2.5 to 8 hours, from the viewpoint of obtaining uniform aggregated particles (2) and shortening the production time of the toner.

[Manufacture of fused particles]
Next, the particles constituting the obtained aggregated particles (2) are fused to obtain fused particles. In this step, the particles in the agglomerated particles (2) that are mainly physically attached to each other are fused and united to form fused particles.

The total amount of the resin particles (B) is added, and aggregation is stopped when the toner particles have grown to an appropriate particle size.
The particle size to stop the aggregation, the volume-median particle size (D _50), from the viewpoint of obtaining a toner of high quality, preferably 1 to 10 [mu] m, more preferably 2 to 8 m, more preferably 3 to 7 [mu] m, 4 More preferably, it is ˜6 μm.
Examples of the method for stopping the aggregation include a method of adding an aqueous medium, a method of cooling the dispersion, and a method of adding an aggregation terminator. From the viewpoint of reliably preventing unnecessary aggregation, the aggregation terminator is used. A method of stopping the aggregation by adding is preferable.
As the aggregation terminator, a surfactant is preferable, and an anionic surfactant is more preferable. Anionic surfactants include alkyl ether sulfates, alkyl sulfates, and linear alkyl benzene sulfonates. The aggregation terminators can be used alone or in combination of two or more.
From the viewpoint of stopping aggregation, the addition amount of the aggregation terminator is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and more preferably 3 parts by mass or more with respect to 100 parts by mass of the total amount of the resin in the system. Further, from the viewpoint of reducing residual toner, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and further preferably 7 parts by mass or less. The aggregation terminator may be added in any form, but is preferably added as an aqueous solution from the viewpoint of improving productivity.

From the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability, it is preferable to crosslink the polyester resin contained in the aggregated particles (2), and it is more preferable to crosslink with a compound having an oxazoline group.
The compound having an oxazoline group preferably contains a plurality of oxazoline groups in the molecule, and more preferably a polymer containing an oxazoline group. The weight average molecular weight of the polymer containing an oxazoline group is preferably 500 to 2,000,000, and more preferably 1,000 to 1,000,000, from the viewpoint of increasing the reactivity with the polyester resin.
Examples of commercially available polymers containing oxazoline groups include EPOCROSS WS series (water-soluble type, main chain acrylic), K series (emulsion type, main chain styrene / acrylic) manufactured by Nippon Shokubai Co., Ltd. Name).
The content or addition amount of the compound having an oxazoline group is from the viewpoint of enhancing the crosslinking reactivity with the resin and improving the productivity, with respect to 100 parts by mass of the total amount of the resin in the dispersion of the aggregated particles (2). The solid content is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, further preferably 5 parts by mass or less, more preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and 1 part by mass. Part or more is more preferable.

  By adding and mixing a compound having an oxazoline group, the polyester resin contained in the aggregated particles (2) dispersed in the dispersion is cross-linked. The addition of the compound having an oxazoline group is preferably performed before the addition of the aggregation terminator, and after the addition of the compound having the oxazoline group, the aggregation terminator is added to fuse the aggregated particles (2) and perform a crosslinking reaction. It is more preferable to carry out simultaneously. 60-100 degreeC is preferable and the temperature at the time of a crosslinking reaction has more preferable 65-90 degreeC. The presence of the crosslinking can be confirmed by analyzing the presence of the amide group by a technique such as infrared absorption spectrum analysis.

  From the viewpoint of improving the fusibility of the agglomerated particles and the productivity of the toner, in this step, the temperature is preferably at least 10 ° C. lower than the glass transition temperature of the resin constituting the agglomerated particles (2). More preferably, the temperature is kept at a temperature not lower than 8 ° C., more preferably not less than 6 ° C., and still more preferably not less than 5 ° C. Further, from the viewpoint of suppressing toner scattering, in this step, the temperature is preferably 20 ° C. or higher, more preferably 15 ° C. or higher, than the glass transition temperature of the resin constituting the aggregated particles (2). More preferably, the temperature is maintained at a temperature not higher than 13 ° C., more preferably not higher than 12 ° C.

  The holding time in this step is 1 to 24 hours from the viewpoint of improving the fusing property of the aggregated particles, the viewpoint of improving the heat resistant storage stability of the toner, the viewpoint of suppressing toner scattering, and the viewpoint of improving the productivity of the toner. Preferably, 1 to 18 hours is more preferable, and 2 to 12 hours is still more preferable.

  From the viewpoint of obtaining a high-quality toner, the volume median particle size of the fused particles obtained in this step is preferably 2 to 10 μm, more preferably 2 to 8 μm, still more preferably 2 to 7 μm, and more preferably 3 to 7 μm. More preferably, 4-6 micrometers is still more preferable.

[Post-processing process]
In the present invention, a post-treatment step may be performed after step (3), and it is preferable to obtain toner particles by isolating the fused particles.
Since the fused particles obtained in the step (3) are present in the aqueous medium, it is preferable to first perform solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used.
It is preferable to perform washing after the solid-liquid separation. When a nonionic surfactant is used in the production of the resin particles (A) and (B), it is preferable to remove the added nonionic surfactant, so the cloud point of the nonionic surfactant In the following, it is preferable to wash with an aqueous medium. The washing is preferably performed a plurality of times.
Next, although it is preferable to dry, the temperature at the time of drying is lower than the glass transition temperature of the resin constituting the fused particles by 5 ° C. or more, and includes crystalline polyester. The temperature is preferably set to be 5 ° C. or more lower than the melting point, and more preferably set to be 10 ° C. or more lower. As a drying method, it is preferable to use a vacuum low temperature drying method, a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like.

  The volume median particle size of the toner particles obtained in this step is preferably from 1 to 10 μm, more preferably from 2 to 8 μm, still more preferably from 3 to 7 μm, from the viewpoint of improving the image quality of the toner and improving the productivity. 4-6 micrometers is still more preferable.

The CV value of the toner particles is preferably 30% or less, more preferably 27% or less, and even more preferably 25% or less, from the viewpoint of improving the image quality of toner and improving productivity.
The volume median particle size and CV value of the toner particles are determined by the method described in the examples.

<Toner for electrophotography>
(toner)
The toner particles obtained by drying or the like can be used as they are as the toner of the present invention, but it is preferable to use toner particles whose surface has been treated as described below as the toner for electrophotography.
The softening point of the obtained toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and still more preferably 60 to 120 ° C., from the viewpoint of improving the low-temperature fixability of the toner and improving the heat-resistant storage stability. . The glass transition temperature is preferably 30 to 80 ° C., more preferably 40 to 70 ° C., from the viewpoint of improving the low-temperature fixability and heat-resistant storage stability of the toner.

(External additive)
In the electrophotographic toner of the present invention, the toner particles can be used as the toner as they are, but it is preferable to use a toner obtained by adding a fluidizing agent or the like to the toner particle surface as an external additive.
Examples of the external additive include inorganic fine particles such as hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, and carbon black, and polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic silica and polymer fine particles are preferable.
When the surface treatment of the toner particles is performed using the external additive, the amount of the external additive added is preferably 1 to 5 parts by mass with respect to 100 parts by mass of the toner particles before the treatment with the external additive. A mass part is more preferable and 2.5-4.5 mass part is still more preferable.

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

  The present invention discloses the following electrophotographic toner manufacturing method and electrophotographic toner relating to the above-described embodiments.

<1> A method for producing an electrophotographic toner comprising the following steps (1) to (3).
Step (1): The acid value is 1 to 20 mgKOH / g, preferably 2 mgKOH / g or more, more preferably 3 mgKOH / g or more, still more preferably 5 mgKOH / g or more, and preferably 18 mgKOH / g or less, More preferably 15 mg KOH / g or less, still more preferably 12 mg KOH / g or less, still more preferably less than 10 mg KOH / g, and still more preferably 9 mg KOH / g or less, polyester resin, nonionic surfactant, ionic surfactant (Preferably anionic surfactant) and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms, preferably 12 to 22, more preferably 14 to 18, and further preferably 16 to 18 are mixed in an aqueous medium. Step of obtaining a dispersion of resin particles (A) Step (2): Resin particles obtained in step (1) Step (3): Aggregated particles (1) obtained in Step (2) Step of mixing (A) dispersion liquid, release agent particles and flocculant in an aqueous medium and aggregating them to obtain aggregated particles (1) Step of adding resin particles (B) to agglomerate and fuse to obtain fused particles

<2> The method for producing a toner for electrophotography according to <1>, wherein the polyester resin has an acid value of 5 to 15 mgKOH / g.
<3> The content of the polyester resin in the resin particles (A) is preferably 80% by mass or more of the resin, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably substantially 100%. <1> or <2> The method for producing a toner for electrophotography according to <1>, further preferably 100% by mass.
<4> The content of the amorphous polyester in the polyester resin in the resin particles (A) is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and still more. The method for producing an electrophotographic toner according to any one of <1> to <3>, preferably substantially 100% by mass, and more preferably 100% by mass.
<5> The mass ratio of the crystalline polyester to the amorphous polyester (crystalline polyester / amorphous polyester) is preferably 5/95 to 50/50, more preferably 10/90 to 20/80. <1>-<4> The manufacturing method of the toner for electrophotography in any one of <4>.

<6> The method for producing an electrophotographic toner according to any one of <1> to <5>, wherein the ionic surfactant is an anionic surfactant.
<7> The mass ratio of the nonionic surfactant to the ionic surfactant (nonionic surfactant / ionic surfactant) is preferably 0.3 to 10, more preferably 0.5 to 5, More preferably, it is 0.8-1.5, The manufacturing method of the toner for electrophotography in any one of <1>-<6>.
<8> The nonionic surfactant is preferably at least one selected from the group consisting of polyoxyethylene alkylaryl ethers, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, and oxyethylene / oxypropylene block copolymers. The method for producing an electrophotographic toner according to any one of <1> to <7>, which is a seed, more preferably a polyoxyethylene alkyl ether, and further preferably a polyoxyethylene oleyl ether.
<9> The ionic surfactant is preferably at least one selected from the group consisting of alkylbenzene sulfonate, alkyl sulfate, and alkyl ether sulfate, more preferably sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, dodecyl ether The method for producing an electrophotographic toner according to any one of <1> to <8>, wherein the toner is at least one selected from the group consisting of sodium sulfate, more preferably sodium dodecylbenzenesulfonate.
<10> The nonionic surfactant is preferably polyoxyethylene alkyl ethers, more preferably polyoxyethylene oleyl ether, and the ionic surfactant is preferably alkylbenzene sulfonate, more preferably dodecylbenzene. The method for producing an electrophotographic toner according to any one of <1> to <9>, which is sodium sulfonate.
<11> The total addition amount of the nonionic surfactant and the ionic surfactant is preferably 20 parts by mass or less, more preferably 15 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (A). Part or less, more preferably 10 parts by weight or less, still more preferably 5 parts by weight or less, preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, and even more preferably 1 part by weight or more. The method for producing an electrophotographic toner according to any one of <1> to <10>.

<12> The method for producing an electrophotographic toner according to any one of <1> to <11>, wherein the monovalent aliphatic carboxylic acid has 12 to 22 carbon atoms.
<13> Monovalent aliphatic carboxylic acid is preferably a saturated aliphatic carboxylic acid, more preferably at least one selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, more preferably The method for producing an electrophotographic toner according to any one of <1> to <12>, wherein the toner is at least one selected from the group consisting of palmitic acid and stearic acid, and more preferably stearic acid.
<14> The addition amount of the monovalent aliphatic carboxylic acid is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and still more preferably 4 with respect to 100 parts by mass of the resin constituting the resin particles (A). Parts by mass or less, more preferably 3 parts by mass or less, preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, still more preferably 0.5 parts by mass or more, and still more preferably. The method for producing an electrophotographic toner according to any one of <1> to <13>, which is 0.8 part by mass or more.
<15> The total addition amount of the monovalent aliphatic carboxylic acid and the surfactant (nonionic surfactant and ionic surfactant) is 100 parts by mass of the resin constituting the resin particles (A). , Preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, and preferably 0.2 parts by mass or more, more preferably 0. The method for producing an electrophotographic toner according to any one of <1> to <14>, which is 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and still more preferably 1.0 parts by mass or more.
<16> The ratio of the addition amount of monovalent aliphatic carboxylic acid to the addition amount of surfactant (nonionic surfactant and ionic surfactant) (monovalent aliphatic carboxylic acid / surfactant) Preferably 10/90 to 90/10, more preferably 20/80 to 70/30, still more preferably 25/75 to 60/40, still more preferably 30/70 to 55/45, <1> The method for producing an electrophotographic toner according to any one of to <15>.

<17> The method for producing an electrophotographic toner according to any one of <1> to <16>, wherein the resin particles (A) contain a colorant.
The addition amount of <18> colorant is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (A). The method for producing an electrophotographic toner according to <17>, wherein the toner content is more preferably 10 parts by mass or less.
<19> Step (1) has an acid value of 1 to 20 mgKOH / g, preferably 2 mgKOH / g or more, more preferably 3 mgKOH / g or more, still more preferably 5 mgKOH / g or more, and preferably 18 mgKOH. Or less, more preferably 15 mgKOH / g or less, still more preferably 12 mgKOH / g or less, still more preferably less than 10 mgKOH / g, and still more preferably 9 mgKOH / g or less, a nonionic surfactant, an ion An aqueous surfactant (preferably anionic surfactant) and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms, preferably 12 to 22, more preferably 14 to 18 and even more preferably 16 to 18 carbon atoms. A step of mixing in a medium and further mixing an aqueous alkali solution to obtain a dispersion of resin particles (A) There, <1> to <18> any method for producing a toner for electrophotography according to the.
<20> The volume median particle size of the resin particles (A) in the dispersion of the resin particles (A) obtained in the step (1) is preferably 2 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm. Or less, more preferably 0.5 μm or less, preferably 0.02 μm or more, more preferably 0.05 μm or more, still more preferably 0.10 μm or more, and even more preferably 0.15 μm or more. The method for producing an electrophotographic toner according to any one of 1> to <19>.

<21> An electrophotographic toner obtained by the production method according to any one of <1> to <20>.
<22> The electron according to <21>, wherein the volume median particle size of the toner particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, still more preferably 3 to 7 μm, and still more preferably 4 to 6 μm. Toner for photography.
<23> The toner for electrophotography according to <21> or <22>, wherein the CV value of the toner particles is preferably 30% or less, more preferably 27% or less, and further preferably 25% or less.
<24> The electrophotographic point according to any one of <21> to <23>, wherein the softening point of the toner is preferably 60 to 140 ° C, more preferably 60 to 130 ° C, and still more preferably 60 to 120 ° C. toner.
<25> The toner for electrophotography according to any one of <21> to <24>, wherein the glass transition temperature of the toner is preferably 30 to 80 ° C, more preferably 40 to 70 ° C.

  Each property value of polyester, resin particles, toner, etc. was measured and evaluated by the following method.

[Acid value of polyester]
It measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Polyester softening point, endothermic maximum peak temperature, crystallinity index, and glass transition temperature]
(1) Softening point Using a flow tester (manufactured by Shimadzu Corporation, trade name: CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C./min, and a load of 1.96 MPa was applied by a plunger. The nozzle was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. The amount of plunger drop of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.
(2) Maximum endothermic peak temperature and crystallinity index Using a differential scanning calorimeter (manufactured by PerkinElmer, trade name: Pyris 6 DSC), it was cooled from room temperature (25 ° C.) to 0 ° C. at a cooling rate of 50 ° C./min. The sample was allowed to stand still for 1 minute, and then heated to 180 ° C. at a heating rate of 10 ° C./min. Among the observed peaks, the temperature of the peak with the largest peak area is defined as the endothermic maximum peak temperature (1), and the crystal is expressed by (softening point (° C)) / (maximum endothermic peak temperature (1) (° C)). The sex index was determined.
(3) Glass transition temperature Using a differential scanning calorimeter (manufactured by PerkinElmer, trade name: Pyris 6 DSC), the temperature was raised to 200 ° C., and the sample cooled to 0 ° C. at a temperature lowering rate of 50 ° C./min was raised. Measurement was performed at a temperature rate of 10 ° C./min. Among the observed endothermic peaks, the temperature of the peak is observed when the peak is observed, and when the step is observed without the peak being observed, the tangent indicating the maximum slope of the curve of the step and the high temperature of the step The temperature at the point of intersection with the extension of the base line on the side was taken as the glass transition temperature.

[Melting point of release agent]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., trade name: DSC210), the temperature is measured from 20 ° C. at a heating rate of 10 ° C./min, and the maximum peak temperature is taken as the melting point.

[Volume Median Particle Size (D ₅₀ ) and CV Value of Resin Particles, Release Agent Particles]
(1) Measuring apparatus: Laser diffraction type particle size measuring instrument (manufactured by Horiba, Ltd., trade name: LA-920)
(2) Measurement conditions: Distilled water was added to the measurement cell, and the volume-median particle size (D ₅₀ ) was measured at a temperature at which the absorbance falls within an appropriate range. The CV value was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[Solid content concentration of resin particle dispersion and release agent particle dispersion]
Using an infrared moisture meter (trade name: FD-230, manufactured by Kett Science Laboratory Co., Ltd.), 5 g of the measurement sample was set to a drying temperature of 150 ° C. and a measurement mode of 96 (monitoring time 2.5 minutes / variation width 0.05%) The moisture percentage was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (% by mass) = 100-M
M: moisture (%) = [(W−W ₀ ) / W] × 100
W: Sample mass before measurement (initial sample mass)
W ₀ : Mass of sample after measurement (absolute dry mass)

[Volume Median Particle Size (D ₅₀ ) and CV Value of Toner Particles, Aggregated Particles, and Fused Particles]
The volume median particle size of the toner particles, aggregated particles, and fused particles was measured as follows.
-Measuring machine: Coulter Multisizer III (trade name, manufactured by Beckman Coulter)
・ Aperture diameter: 50μm
-Analysis software: Multisizer III version 3.51 (trade name, manufactured by Beckman Coulter)
・ Electrolyte: Isoton II (trade name, manufactured by Beckman Coulter)
-Dispersion: Polyoxyethylene lauryl ether (trade name: Emulgen 109P, HLB: 13.6, manufactured by Kao Corporation) was dissolved in the electrolytic solution to obtain a dispersion having a concentration of 5% by mass.
-Dispersion condition: 10 mg of a toner measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, and then 25 mL of electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. A sample dispersion was prepared.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolytic solution to adjust the particle size of 30,000 particles to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size distribution thereof. From this, the volume median particle size (D ₅₀ ) was determined. When measurement is performed on the aggregated particles in the aggregated particle dispersion and the fused particles in the fused particle dispersion, the aggregated particle dispersion and the fused particle dispersion are used as the sample dispersion in the electrolyte solution. In addition, the concentration adjusted was used for the measurement.
The CV value (%) was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[Evaluation of low-temperature fixability of toner]
Using a commercially available printer (trade name: Microline 5400, manufactured by Fuji Xerox Co., Ltd., J paper A4 size), the toner adhesion amount on the paper is 0.42 to 0.48 mg / cm ² . The resulting solid image was output without being fixed at a length of 50 mm, leaving a margin of 5 mm from the top edge of the A4 paper.
Next, the same printer with the temperature-variable fixing device prepared was prepared, the temperature of the fixing device was set to 90 ° C., and fixing was performed at a speed of 1.5 seconds per sheet in the A4 longitudinal direction, thereby obtaining a printed matter.
In the same manner, the temperature of the fixing device was increased by 5 ° C. and fixed, and a printed matter was obtained.
500 g of a mending tape (product name: Scotch Mending Tape 810, width 18 mm) cut to a length of 50 mm is lightly pasted from the margin at the top of the printed image to a solid image. A weight was placed and pressed once back and forth at a speed of 10 mm / sec. Thereafter, the affixed tape was peeled off from the lower end side at a peeling angle of 180 degrees and at a speed of 10 mm / sec to obtain a printed matter after the tape was peeled off. Thirty sheets of high-quality paper (Oki Data Co., Ltd., Excellent White Paper A4 size) are placed under the printed material before tape application and after peeling, and the reflected image density of the fixed image before tape application and after peeling is measured. Measurement was performed using a colorimeter (manufactured by GretagMacbeth, trade name: SpectroEye, light emission condition; standard light source D ₅₀ , observation field of view 2 °, density reference DINNB, absolute white reference), and the fixing ratio was calculated from the following formula. .
Fixing rate = (reflected image density after peeling tape / reflected image density before applying tape) × 100
The temperature at which the fixing rate was 90% or more was defined as the minimum fixing temperature. The lower the minimum fixing temperature, the better the low-temperature fixing property.

[Evaluation of heat-resistant storage stability of toner]
20 g of toner was put in a wide-mouthed polybin having an internal volume of 100 ml, sealed, and allowed to stand for 12 hours in an environment at a temperature of 55 ° C. Thereafter, it was allowed to stand for 12 hours or more while being sealed at a temperature of 25 ° C. and cooled. Next, three different sieve openings are set in the order of 250 μm in the upper stage, 150 μm in the middle stage, and 75 μm in the lower stage on the shaking table of a powder tester (trade name, manufactured by Hosokawa Micron Corporation), and 2 g of the toner is placed thereon for 60 seconds. Vibration was performed and the amount of toner remaining on each screen was measured.
The measured toner mass was calculated by applying to the following formula to determine the degree of aggregation [%]. The smaller the value, the better the heat resistant storage stability of the toner.
Aggregation degree [%] = a + b + c
a = (Mass of residual toner on upper screen) / 2 [g] × 100
b = (middle stage residual toner mass) / 2 [g] × 100 × (3/5)
c = (lower stage residual toner mass) / 2 [g] × 100 × (1/5)

[Production of polyester]
Production Example 1
(Production of polyester A)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3374 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Put 33 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 672 g of terephthalic acid, and 10 g of dibutyltin oxide, and raise the temperature to 230 ° C. with stirring in a nitrogen atmosphere. After maintaining for 5 hours, the pressure in the flask was further lowered and maintained at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 696 g of fumaric acid and 0.49 g of tert-butylcatechol were added and maintained at a temperature of 210 ° C. for 5 hours. Polyester A was obtained by maintaining at 3 kPa for 4 hours. The acid value of the obtained polyester A was 8.4 mgKOH / g. The softening point was 104 ° C., the maximum endothermic peak temperature was 70 ° C., the crystallinity index was 1.5, and the glass transition temperature was 59 ° C.

Production Example 2
(Production of polyester B)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 2205 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Put 3803 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 2749 g of terephthalic acid, and 10 g of dibutyltin oxide, and raise the temperature to 230 ° C. with stirring in a nitrogen atmosphere. After maintaining for 5 hours, the pressure in the flask was further lowered and maintained at 8.3 kPa for 4 hours to obtain polyester B. The acid value of the obtained polyester B was 5.4 mgKOH / g. The softening point was 109 ° C, the maximum endothermic peak temperature was 73 ° C, the crystallinity index was 1.5, and the glass transition temperature was 67 ° C.

Production Example 3
(Production of polyester C)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 1750 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 1625 g, terephthalic acid 939 g, dodecenyl succinic anhydride 132 g, trimellitic anhydride 394 g, and dibutyltin oxide 10 g are placed in a nitrogen atmosphere. Under stirring, the temperature was raised to 220 ° C. and maintained at 220 ° C. for 5 hours to obtain polyester C. The acid value of the obtained polyester C was 21.0 mgKOH / g. The softening point was 121 ° C., the maximum endothermic peak temperature was 76 ° C., the crystallinity index was 1.6, and the glass transition temperature was 64 ° C.

Production Example 4
(Production of polyester D)
The inside of the four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3004 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, After adding 996 g of fumaric acid, 2 g of tert-butylcatechol, and 8 g of dibutyltin oxide, heating to 210 ° C. over 5 hours with stirring in a nitrogen atmosphere and holding at 210 ° C. for 2 hours The polyester D was obtained by reacting at 8.3 kPa until the softening point reached 100 ° C. The acid value of the obtained polyester D was 22.4 mgKOH / g. The softening point was 101 ° C., the maximum endothermic peak temperature was 67 ° C., the crystallinity index was 1.5, and the glass transition temperature was 58 ° C.

[Production of release agent particle dispersion]
Production Example 5
(Production of release agent particle dispersion)
In a beaker with an internal volume of 1 liter, 200 g of deionized water and 3.8 g of a sodium acrylate-sodium maleate copolymer aqueous solution (trade name: Poise 521, Kao Corporation, effective concentration 40% by mass) as a sodium polycarboxylate aqueous solution After dissolution, 5 g of carnauba wax (trade name: Carnauba wax No. 1, melting point 83 ° C.) and paraffin wax (trade name: HNP-9, trade name: HNP-9, melting point 75 ° C.) 45 g was added, and the mixture was melted while maintaining the temperature at 90 to 95 ° C. to obtain a molten mixture in which carnauba wax and paraffin wax were melted together.
The aqueous solution containing the obtained molten mixture was further subjected to a dispersion treatment for 30 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho, trade name: US-600T) while maintaining the temperature at 90 to 95 ° C. Then, it cooled to 25 degreeC, deionized water was added, solid content was adjusted to 20 mass%, and the mold release agent particle dispersion liquid was obtained. The volume median particle size (D ₅₀ ) of the release agent particles was 0.450 μm, and the CV value was 30%.

[Production of resin particle dispersion: Step (1)]
Production Example P1
(Preparation of dispersion of resin particles (1))
In a flask equipped with a stirrer, 600 g of polyester A, 45 g of copper phthalocyanine pigment (trade name: ECB301, manufactured by Dainichi Seika Kogyo Co., Ltd.), polyoxyethylene oleyl ether (nonionic surfactant, trade name: Emulgen 430, Kao) 6 g, 15 mass% sodium dodecylbenzenesulfonate aqueous solution (anionic surfactant, trade name: Neoperex G-15, manufactured by Kao Corporation) 40 g, stearic acid 6.0 g, and 95 ° C. with stirring. The mixture was heated and melted to obtain a resin mixture.
Next, 268 g of 5 mass% potassium hydroxide aqueous solution was added while stirring, and mixing was performed at 95 ° C. for 2 hours while stirring. While maintaining the temperature of the system at 95 ° C., 1145 g of deionized water was added dropwise at a rate of 6 g / min while stirring to obtain an emulsion. The obtained emulsion was cooled to 25 ° C., and a dispersion of resin particles (1) was obtained through a 200 mesh (mesh 105 μm) wire mesh. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (1), the volume median particle size and the CV value of the resin particles (1). In this specification, Table 2-1 and Table 2-2 are collectively referred to as Table 2.

Production Example P2
(Preparation of dispersion of resin particles (2))
In Production Example P1, a dispersion of resin particles (2) was obtained in the same manner as in Production Example P1, except that 600 g of polyester A was changed to 390 g of polyester B and 210 g of polyester C. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (2), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (2).

Production Example P3
(Preparation of dispersion of resin particles (3))
In Production Example P1, a dispersion of resin particles (3) was obtained in the same manner as in Production Example P1, except that 600 g of polyester A was changed to 390 g of polyester A and 210 g of polyester C. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (3), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (3).

Production Example P4
(Preparation of dispersion of resin particles (4))
In Production Example P1, a dispersion of resin particles (4) was obtained in the same manner as in Production Example P1, except that stearic acid was changed to 12 g. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (4), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (4).

Production Example P5
(Preparation of dispersion of resin particles (5))
In Production Example P1, a dispersion of resin particles (5) was obtained in the same manner as in Production Example P1, except that stearic acid was changed to palmitic acid. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (5), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (5).

Production Example P6
(Preparation of dispersion of resin particles (6))
A dispersion of resin particles (6) was obtained in the same manner as in Production Example P1, except that stearic acid was changed to myristic acid in Production Example P1. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (6), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (6).

Comparative production example P7
(Preparation of dispersion of resin particles (7))
In Production Example P1, except that stearic acid was changed to sodium stearate, an attempt was made to prepare a dispersion of resin particles (7) in the same manner as in Production Example P1, but the resin could not be dispersed and resin particles (7 ) Was not obtained.

Comparative production example P8
(Preparation of dispersion of resin particles (8))
In Production Example P1, an attempt was made to prepare a dispersion of resin particles (8) in the same manner as in Production Example P1 except that stearic acid was not added. However, the resin could not be dispersed and the resin particles (8) A dispersion could not be obtained.

Comparative production example P9
(Preparation of dispersion of resin particles (9))
In Production Example P3, an attempt was made to prepare a dispersion of resin particles (9) in the same manner as in Production Example P3 except that the 15% by mass sodium dodecylbenzenesulfonate aqueous solution was not added. However, the resin could not be dispersed. A dispersion of resin particles (9) could not be obtained.

Comparative production example P10
(Preparation of dispersion of resin particles (10))
In Production Example P1, 6.0 g of stearic acid was changed to 24 g of sodium stearate, and the resin particles (10) were prepared in the same manner as in Production Example P1, except that a 15% by mass aqueous sodium dodecylbenzenesulfonate solution was not added. Although an attempt was made to prepare a dispersion, the resin could not be dispersed and a dispersion of resin particles (10) could not be obtained.

Comparative production example P11
(Preparation of dispersion of resin particles (11))
Preparation of dispersion of resin particles (11) in the same manner as in Production Example P1, except that stearic acid was not added in Production Example P1 and the addition amount of the 15% by mass aqueous sodium dodecylbenzenesulfonate solution was changed to 160 g. However, the resin could not be dispersed and a dispersion of resin particles (11) could not be obtained.

Comparative production example P12
(Preparation of dispersion of resin particles (12))
Resin particles (12) were produced in the same manner as in Production Example P1, except that stearic acid and a 15% by mass aqueous sodium dodecylbenzenesulfonate solution were not added and the amount of polyoxyethylene oleyl ether added was changed to 60 g. The dispersion of resin particles (12) could not be obtained because the resin could not be dispersed.

Comparative production example P13
(Preparation of dispersion of resin particles (13))
A dispersion of resin particles (13) was obtained in the same manner as in Production Example P1, except that in Production Example P1, 600 g of polyester A was changed to 390 g of polyester D and 210 g of polyester C. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (13), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (13).

Comparative Production Example P14
(Preparation of dispersion of resin particles (14))
In Comparative Production Example P13, a dispersion of resin particles (14) was obtained in the same manner as Comparative Production Example P13, except that stearic acid was not added. Table 2 shows the solid content concentration of the dispersion of the obtained resin particles (14), the volume median particle size (D ₅₀ ), and the CV value of the resin particles (14).

[Production of toner]
Example 1
(Preparation of Toner 1)
<Step (2): Production of Aggregated Particle (1)>
Into a 2 l four-necked flask equipped with a dehydrating tube, a stirrer and a thermocouple, 250 g of a dispersion of resin particles (1), 62 g of deionized water, and 21 g of a release agent particle dispersion are placed, and the temperature is 25 ° C. Mixed. Next, an aqueous solution obtained by dissolving 22.8 g of ammonium sulfate in 243 g of deionized water was added dropwise over 30 minutes while stirring at 25 ° C., and then the mixture was heated to 55 ° C. over 120 minutes, and the volume of aggregated particles was increased. The mixture was kept at 55 ° C. until the median particle size became 4.5 μm to obtain agglomerated particles (1).

<Step (3): Preparation of fused particles>
After cooling the temperature of the dispersion (total amount) of the aggregated particles (1) obtained in step (2) to 50 ° C., the temperature is raised at a rate of 1 ° C. per hour, and 72 g of the dispersion of resin particles (1) A mixed solution obtained by mixing 22 g of deionized water was dropped over 180 minutes to obtain aggregated particles (2). The volume-median particle size of the obtained aggregated particles (2) was 4.9 μm.
To the dispersion (total amount) of the obtained aggregated particles (2), 5.1 g of an oxazoline group-containing polymer (trade name: Epocross WS-700, manufactured by Nippon Shokubai Co., Ltd., effective content 25%) was added and stirred for 30 minutes. Next, an aqueous solution obtained by mixing 16.0 g of polyoxyethylene lauryl ether sodium sulfate aqueous solution (anionic surfactant, trade name: EMAL E-27C, manufactured by Kao Corporation, solid content 28% by mass) with 625 g of deionized water is added. After that, the temperature was raised to 70 ° C. over 1 hour and held at 70 ° C. for 3 hours to obtain a dispersion containing fused particles having a volume-median particle size of 4.8 μm. Then, it cooled to 25 degreeC.

<Post-processing process>
While maintaining the fused particle dispersion obtained in step (3) at 25 ° C., the solid content is separated by suction filtration, washed with deionized water, and vacuum low-temperature dryer (manufactured by ADVANTEC Toyo Co., Ltd., model name: DRV622DA) at 33 ° C. to obtain toner particles. Table 3 shows the volume-median particle size and CV value of the obtained toner particles. To 100 parts by mass of the toner particles, 2.5 parts by mass of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., trade name: RY50, number average particle size; 0.04 μm), hydrophobic silica (manufactured by Cabot Corporation, trade name: Cabo seal TS720, number average particle size: 0.012 μm) 1.0 part by mass, and polymer fine particles (manufactured by Nippon Paint Co., Ltd., trade name: Finesphere P2000, number average particle size: 0.5 μm) 0.8 part by mass It was put into a mixer, stirred, and passed through a 150 mesh sieve to obtain toner 1. Table 3 shows the physical properties and evaluation of the obtained toner.

Examples 2-6 and Comparative Examples 1-2
(Production of toners 2 to 8)
Toners 2 to 8 were obtained in the same manner as in Example 1, except that the resin particle (1) dispersion was changed to the resin particle dispersion shown in Table 3. Table 3 shows the physical properties and evaluation of the obtained toner.

  From Table 2, it can be seen that in Production Examples P1 to P6, a polyester resin having a low acid value can be stably emulsified as compared with Comparative Production Examples P7 to P14. Further, from Table 3, the toners of Examples 1 to 6 produced using the resin particle dispersions of Production Examples P1 to P6 are the same as those of Comparative Examples 1 and 6 produced using the resin particle dispersions of Comparative Production Examples P13 and P14. It can be seen that each of the toners is excellent in heat-resistant storage stability while maintaining low-temperature fixability as compared with the toner No. 2.

  Since the electrophotographic toner obtained by the production method of the present invention is excellent in heat-resistant storage stability, it can be suitably used as an electrophotographic toner used in electrophotography, electrostatic recording method, electrostatic printing method and the like. According to the method of the present invention, a toner having such characteristics can be produced efficiently.

Claims (7)

A method for producing an electrophotographic toner comprising the following steps (1) to (3):
Step (1): A polyester resin having an acid value of 1 to 20 mgKOH / g, a nonionic surfactant, an ionic surfactant, and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms are mixed in an aqueous medium. Step of obtaining a dispersion of resin particles (A) Step (2): The dispersion of resin particles (A) obtained in step (1), the release agent particles and the flocculant are mixed in an aqueous medium for aggregation. Step of obtaining the aggregated particles (1) Step (3): The resin particles (B) are added to the aggregated particles (1) obtained in the step (2) to cause aggregation and fusion. Obtaining process   The method for producing an electrophotographic toner according to claim 1, wherein the addition amount of the monovalent aliphatic carboxylic acid is 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin constituting the resin particles (A). .   The method for producing an electrophotographic toner according to claim 1, wherein the acid value of the polyester resin is 5 to 15 mg KOH / g.   In step (1), a polyester resin having an acid value of 1 to 20 mgKOH / g, a nonionic surfactant, an ionic surfactant, and a monovalent aliphatic carboxylic acid having 12 to 26 carbon atoms in an aqueous medium The method for producing an electrophotographic toner according to any one of claims 1 to 3, which is a step of mixing and further mixing an aqueous alkali solution to obtain a dispersion of resin particles (A).   The method for producing an electrophotographic toner according to claim 1, wherein the monovalent aliphatic carboxylic acid has 12 to 22 carbon atoms.   The method for producing an electrophotographic toner according to claim 1, wherein the polyester resin contains 80 to 100 mass% of amorphous polyester.   The method for producing an electrophotographic toner according to claim 1, wherein the resin particles (A) contain a colorant.