JP5607518B2 - Method for producing toner for developing electrostatic latent image - Google Patents

Description

  The present invention relates to a method for producing an electrostatic latent image developing toner and an electrostatic latent image developing toner obtained thereby.

In the field of electrostatic latent image developing toner, with the development of electrophotographic systems, development of toners corresponding to higher image quality and higher speed is required.
To cope with higher image quality and higher speed, toners are also required to have various performances. In order to meet these requirements, color particles and resin emulsified particles are agglomerated, and the particle size and surface properties are arbitrarily adjusted. As a method that can be used, a toner production method using an emulsion aggregation method has been proposed.

  For example, Patent Document 1 discloses a process of melt-kneading a toner material containing a binder resin containing polyester and a release agent for the purpose of improving heat-resistant storage stability and widening the fixing temperature range, The method for producing an electrophotographic toner comprising the steps of emulsifying the emulsion in an aqueous medium, aggregating the emulsified particles in the emulsion, and coalescing the aggregated particles, and further adding a polymer having an oxazoline group Is disclosed.

  Patent Document 2 discloses that the release agent particles are uniformly dispersed in the toner particles, are not exposed on the surface, have a narrow particle size distribution, and provide sharp toner particles. Preliminarily finely disperse a binder resin having a carboxyl group in an organic solvent, and stabilize it with a high-pressure homogenizer to form a release agent stable fine dispersion, and then add and disperse the binder resin having a carboxyl group and an organic pigment into the colored resin solution. A basic compound is added thereto to emulsify the colored resin solution in an aqueous medium to form fine particles of the colored resin solution, and then a dispersion stabilizer and an electrolyte are sequentially added to form a unity of the fine particles. After removing the organic solvent in the fine particles of the colored resin solution and adding an electrolyte to form an aggregate of the fine particles. KoToruchaku is allowed to method for producing a toner for developing electrostatic images to form an aggregate is disclosed.

  Patent Document 3 discloses a core layer containing a binder resin made of a polyester resin, a release agent made of an ester wax, and a colorant for the purpose of improving charging properties and preventing the colorant from being exposed to the toner surface. And a shell layer covering the surface of the core layer, the volume average particle diameter is 3 μm to 8 μm, and the ratio of the colorant present in the region within 200 nm from the outermost surface of the toner is 10% or less. Image developing toners are disclosed.

  In Patent Document 4, a mixture particle containing a binder resin and a colorant is added to an aqueous medium for the purpose of reducing the particle size and controlling the shape without using an organic solvent, and improving fixability and storage stability. The dispersion is dispersed in and introduced into a mechanical shearing device including a heating part, a mechanical shearing part, and a cooling part, and under a specific condition, the dispersion is heated above the glass transition temperature of the polyester resin. A method for producing a developer that obtains fine particles by cooling after being subjected to shearing is disclosed.

JP 2009-192699 A JP 2005-49394 A JP 2007-57664 A JP 2009-145893 A

In order to reduce power consumption during printing and to support high-speed printing, fixability particularly at low temperatures is required. By using a release agent in the toner, the fixing temperature region of the obtained toner can be adjusted from its melting characteristics. However, when a release agent having a low melting point is used in order to ensure fixability at a low temperature, there is a problem that the storage stability of the toner at a relatively high temperature is lowered. On the other hand, as disclosed in Patent Document 1, the resin is made into a cross-linked structure, or as disclosed in Patent Document 3, the core-shell structure is used to confine the release agent inside. Is still inadequate.
An object of the present invention is to provide a toner for developing an electrostatic latent image that is excellent in low-temperature fixability and heat-resistant storage stability, and a method for producing the same.

  The present inventors consider that the factor affecting the low-temperature fixability and heat-resistant storage stability is that the release agent is exposed to the surface, and that the cause is the presence of the release agent in the toner. Study was carried out. As a result, by using release agent particles containing a specific weight ratio of wax and polyester resin, the particles are agglomerated together with resin particles containing polyester resin to form a core-shell structure, and then fused, thereby achieving low temperature fixability and heat resistance. It has been found that a toner for developing an electrostatic latent image having excellent storage stability can be obtained.

That is, the present invention provides the following [1] and [2].
[1] A method for producing a toner for developing an electrostatic latent image, comprising the following steps (1) to (3).
Step (1): Resin particles (A) containing a resin containing 90% by weight or more of polyester resin (a), wax and polyester resin (b) having a softening point of 75 to 105 ° C. in weight ratio (wax / polyester) Resin (b)) Step of obtaining aggregated particles (1) by mixing release agent particles contained in 95/5 to 55/45 and an aggregating agent in an aqueous medium Step (2): Aggregated particles (1) The step of mixing the resin particles (B) containing the polyester resin (c) to be the shell to obtain the aggregated particles (2) Step (3): Fusing the particles constituting the aggregated particles (2) Step of obtaining core-shell particles [2] A toner for developing an electrostatic latent image obtained by the production method according to [1].

  According to the present invention, it is possible to provide an electrostatic latent image developing toner excellent in low-temperature fixability and heat-resistant storage stability, and a method for producing the same.

[Method for producing toner for developing electrostatic latent image]
The method for producing a toner for developing an electrostatic latent image of the present invention includes the following steps (1) to (3).
Step (1): Resin particles (A) containing a resin containing 90% by weight or more of polyester resin (a), wax and polyester resin (b) having a softening point of 75 to 105 ° C. in weight ratio (wax / polyester) Resin (b)) Step of obtaining aggregated particles (1) by mixing release agent particles contained in 95/5 to 55/45 and an aggregating agent in an aqueous medium Step (2): Aggregated particles (1) The step of mixing the resin particles (B) containing the polyester resin (c) to be the shell to obtain the aggregated particles (2) Step (3): Fusing the particles constituting the aggregated particles (2) , A step of obtaining core-shell particles

The reason why the toner for developing an electrostatic latent image obtained by the production method of the present invention is excellent in low-temperature fixability and heat-resistant storage stability is not clear, but can be considered as follows.
First, in step (1) in the method of the present invention, resin particles (A) substantially consisting of a polyester resin (a), and release agent particles containing a wax and a polyester resin (b) in a certain ratio are provided. Flocculate in an aqueous medium using a flocculant. Then, in the step (2), the resin particles (B) containing the polyester resin (c) are mixed, and in the step (3), fusion is performed, and the core shell using the resin containing the polyester resin (c) as a shell. Fusing particles to be a toner having a structure are obtained.
In the present invention, by using the release agent particles containing the wax and the polyester resin (b) at a specific ratio, the polyester resin is substantially improved while maintaining the release property of the release agent and improving the low-temperature fixability. The affinity between the resin particles (A) comprising (a) and the release agent is increased, and the wax is separated from these resins even when the particles are heated and the wax or resin is partially melted in the fusing process. It is thought that it keeps the contained state without doing. Furthermore, in the present invention, since the resin containing a polyester resin is used in the shell portion as well as the resin particles and release agent particles forming the core portion, the adhesion between the core and the shell is excellent, and the release agent particles and Since the affinity with the resin particles (B) constituting the shell is also high, a shell structure is also formed in the wax portion of the core, and it is considered that the exposure of the wax to the surface is suppressed. Further, the release agent particles themselves have a core-shell structure with a wax as a core and a resin as a shell, which may further enhance the above effects. As described above, it is considered that the toner of the present invention can introduce sufficient wax into the toner to exhibit low-temperature fixability while maintaining heat-resistant storage stability.
Hereinafter, each component used in the present invention will be described.

(Resin particles (A))
The resin constituting the resin particles (A) used in the present invention improves the low-temperature fixability and heat-resistant storage stability of the toner, and from the viewpoint of achieving both, the polyester resin (a) in the resin constituting the resin particles (A). Is 90 to 100% by weight, preferably 90 to 100% by weight, more preferably 95 to 100% by weight, still more preferably 100% by weight.

<Polyester resin (a)>
The polyester resin (a) in the present invention may be either an amorphous polyester or a crystalline polyester, and may be a mixture. From the viewpoint of improving the low-temperature fixability, heat-resistant storage stability and chargeability of the toner and preventing hot offset. The amount of the amorphous polyester in the polyester resin (a) is preferably 70 to 100% by weight, more preferably 90 to 100% by weight, and further preferably substantially 100% by weight.
The “amorphous” polyester is a ratio of the softening point to the maximum endothermic peak temperature by a differential scanning calorimeter (DSC), (softening point (° C.)) / (Maximum endothermic peak temperature (° C.)). A defined crystallinity index is a polyester having a crystallinity index greater than 1.4 or less than 0.6, and a “crystalline” polyester is one having a crystallinity index of 0.6 to 1.4.

In the present invention, the crystallinity index of the polyester resin (a) is preferably less than 0.6 or more than 1.4 and 4 or less, more preferably less than 0.6 or 1.5 from the viewpoint of low-temperature fixability of the toner. It is 4 or less, more preferably less than 0.6 or 1.5 or more and 3 or less, more preferably less than 0.6 or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined depending on the type and ratio of raw material monomers, production conditions (eg, reaction temperature, reaction time, cooling rate), and the like.
The polyester resin (a) is preferably a polyester having an acid group at the molecular end. Examples of the acid group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid. Among these, a carboxyl group is preferable from the viewpoint of promoting emulsification of the polyester.

The polyester resin (a) is obtained by polycondensation reaction of a carboxylic acid component and an alcohol component. The polycondensation reaction is preferably performed at 140 to 200 ° C. in the presence of a catalyst.
Examples of the carboxylic acid component include dicarboxylic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, trivalent or higher polyvalent carboxylic acid, and acid anhydrides thereof and the like Alkyl (1 to 3 carbon atoms) ester, and the like. Among these, dicarboxylic acid is preferable.
Examples of the dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, and cyclohexanedicarboxylic acid. Among these, terephthalic acid is preferable.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and the like. Among these, trimellitic acid and acid anhydride thereof from the viewpoint of offset resistance. Things are preferred.
These carboxylic acid components can be used alone or in combination of two or more.
The polyester resin (a) uses a trivalent or higher polyvalent carboxylic acid and an acid anhydride or an alkyl ester thereof, preferably an acid component containing trimellitic acid or an anhydride thereof from the viewpoint of offset resistance of the toner. It is preferable to use at least one polyester resin obtained in this way.

Examples of the alcohol component include aromatic diols, aliphatic diols having 2 to 12 carbon atoms, hydrogenated products of bisphenol A, trihydric or higher polyhydric alcohols, and among these, amorphous From the viewpoint of obtaining a polyester, an aromatic diol is preferred.
Preferred aromatic diols include alkylenes of bisphenol A such as polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane (carbon number 2). -3) Oxide adduct (average number of added moles 1 to 16).
Examples of the aliphatic diol having 2 to 12 carbon atoms include α, ω-linear alkanediol, and specific examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4 -Butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12- And dodecanediol.
Examples of other aliphatic diols having 2 to 12 carbon atoms include neopentyl glycol and 1,4-butenediol.
These alcohol components can be used alone or in combination of two or more.

The glass transition point of the polyester resin (a) is preferably 55 to 75 ° C., more preferably 55 to 70 ° C., and still more preferably 58 to 68 ° C., from the viewpoint of toner durability, low-temperature fixability and storage stability. is there.
From the same viewpoint, the softening point of the polyester resin (a) is preferably 70 to 165 ° C, more preferably 70 to 140 ° C, still more preferably 90 to 140 ° C, and further preferably 100 to 130 ° C.
In addition, when using 2 or more types of polyester resin (a) mixed, the glass transition point and softening point are the values obtained by the method of an Example as a mixture of 2 or more types of polyester resins (a), respectively. It is.

The number average molecular weight of the polyester resin (a) is preferably 1,000 to 50,000, more preferably 1,000 to 10,000, and still more preferably, from the viewpoints of toner durability, low-temperature fixability and storage stability. Is 2,000 to 8,000.
The acid value of the polyester resin (a) is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 35 mgKOH / g, from the viewpoint of emulsification in the aqueous medium of the resin.

  The polyester resin (a) preferably contains two kinds of polyesters having different softening points from the viewpoints of low-temperature fixability, offset resistance and durability of the toner. When two types of polyesters having different softening points are polyesters (a-1) and (a-2), respectively, the softening point of one polyester (a-1) is preferably 70 ° C. or higher and lower than 115 ° C., The softening point of the polyester (a-2) is preferably 115 ° C or higher and 165 ° C or lower. The weight ratio of polyester (a-1) to polyester (a-2) ((a-1) / (a-2)) is preferably 10/90 to 90/10, more preferably 50/50 to 90. / 10.

The resin particles (A) may contain a resin other than the polyester resin (a), for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, and a polyurethane as long as the effects of the present invention are not impaired. .
The resin particles (A) may contain a release agent and a charge control agent as long as the effects of the present invention are not impaired. If necessary, reinforcing fillers such as fibrous substances, antioxidants, You may contain additives, such as anti-aging agent.

The resin particle (A) may be a particle consisting of only a resin or a colorant-containing resin particle containing a colorant. From the viewpoint of suppressing the generation of coarse particles during aggregation, a colorant is used. The colorant-containing resin particles are preferably contained.
When the resin particles are particles composed only of a resin, colorant particles obtained by subjecting the colorant to surface treatment or using a dispersant in step (2) described in detail later. Alternatively, it is preferable to further use colorant-containing resin particles obtained by adding a colorant to the resin particles.
When the resin particles (A) are colorant-containing resin particles, the content of the colorant is preferably 1 to 100 parts by weight of the resin constituting the colorant-containing resin particles from the viewpoint of the image density of the toner. 20 parts by weight, more preferably 5 to 10 parts by weight.

<Colorant>
As the colorant used in the toner of the present invention, pigments and dyes are used, and pigments are preferable from the viewpoint of toner image density.
Specific examples of the pigment include carbon black, inorganic composite oxide, chrome yellow, benzidine yellow, brilliantamine 3B, brilliantamine 6B, Bengal, aniline blue, ultramarine blue, copper phthalocyanine, phthalocyanine green, and the like. Phthalocyanine is 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 or in combination of 2 or more types.

<Manufacture of resin particles (A)>
The resin particles (A) can be produced by a method in which a resin containing 90% by weight or more of the polyester resin (a) and the above optional components are dispersed in an aqueous medium to obtain a dispersion containing the resin particles (A). preferable.
Examples of a method for obtaining a dispersion include a method in which a resin or the like is added to an aqueous medium and a dispersion treatment is performed using a disperser or the like, and a method in which an aqueous medium is gradually added to a resin or the like to perform phase inversion emulsification. From the viewpoint of low-temperature fixability of the toner, a method using phase inversion emulsification is preferred. Hereinafter, a method by phase inversion emulsification will be described.

First, the resin containing the polyester resin (a), the alkaline aqueous solution, and the above-mentioned optional components are melted and mixed to obtain a resin mixture.
When the resin particles (A) are colorant-containing resin particles, it is preferable to mix a colorant to obtain a colored resin mixture.
When the resin containing the polyester resin (a) is composed of a plurality of resins, a mixture of the polyester resin (a) and other resins may be used in advance, but the alkaline aqueous solution and optional components are added. It may be obtained by adding at the same time, melting and mixing. For example, in the case of containing a plurality of polyester resins (a), from the viewpoint of low-temperature fixability of the toner, the plurality of polyester resins (a), an aqueous alkali solution, and the above optional components, preferably a colorant are melted and mixed. A method of obtaining a resin mixture is preferred.
In mixing, it is preferable to add a surfactant from the viewpoint of the emulsion stability of the resin.

  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 dispersibility of the resin, potassium hydroxide and sodium hydroxide are preferable. . The concentration of alkali in the aqueous alkali solution is preferably 1 to 30% by weight, more preferably 1 to 25% by weight, and still more preferably 1.5 to 20% by weight.

Examples of the surfactant include nonionic surfactants, anionic surfactants, and cationic surfactants. Among them, nonionic surfactants are preferable, and nonionic surfactants and anionic surfactants are preferred. It is more preferable to use an active agent or a cationic surfactant in combination, and it is more preferable to use a nonionic surfactant and an anionic surfactant in combination from the viewpoint of sufficiently emulsifying the resin.
When a nonionic surfactant and an anionic surfactant are used in combination, the weight ratio of the nonionic surfactant to the anionic surfactant (nonionic surfactant / anionic surfactant) is: From the viewpoint of sufficiently emulsifying the resin, it is preferably 0.3 to 10, more preferably 0.5 to 5.

Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyethylene glycol monolaurate , Polyoxyethylene fatty acid esters such as polyethylene glycol monostearate and polyethylene glycol monooleate, and oxyethylene / oxypropylene block copolymers. Among these, from the viewpoint of emulsion stability of the resin, polyoxyethylene alkyl Ethers are preferred.
Examples of the anionic surfactant include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, etc. Among these, from the viewpoint of emulsion stability of the resin, sodium dodecyl benzene sulfonate, Sodium alkyl ether sulfate is preferred.
Examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

  The content of the surfactant is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, still more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A). More preferably, it is 0.5 to 10 parts by weight.

As a method for obtaining a resin mixture, a resin containing a polyester resin (a), an alkaline aqueous solution, and the above optional components, preferably a surfactant, are placed in a container, and the resin is melted uniformly while stirring with a stirrer. A method of mixing is preferred.
The temperature at which the resin is melted and mixed is preferably equal to or higher than the glass transition point of the polyester resin (a).

Next, an aqueous medium is added to the resin mixture and phase inversion is performed to obtain a dispersion containing resin particles (A).
As the aqueous medium, those containing water as a main component are preferable. From the viewpoint of heat-resistant storage stability and environmental properties, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more. Preferably it is 95 weight% or more, More preferably, it is substantially 100 weight%. The water used is preferably deionized water or distilled water.
As components other than water, organic solvents that dissolve in water such as alkyl alcohols having 1 to 5 carbon atoms; dialkyl (carbon numbers 1 to 3) ketones such as acetone and methyl ethyl ketone; and cyclic ethers such as tetrahydrofuran are used. Among these, from the viewpoint of preventing mixing into the toner, an alkyl alcohol having 1 to 5 carbon atoms that does not dissolve the polyester is preferable, and methanol, ethanol, isopropanol, and butanol are more preferable.
The temperature at which the aqueous medium is added is preferably equal to or higher than the glass transition point of the polyester resin (a).

  The addition rate of the aqueous medium is preferably 0.1 to 50 weights with respect to 100 parts by weight of the resin constituting the resin particles (A) until the phase inversion is completed from the viewpoint of making the resin particles have a small particle size. Part / minute, more preferably 0.1 to 30 parts by weight / minute, still more preferably 0.5 to 10 parts by weight / minute, still more preferably 0.5 to 5 parts by weight / minute. In addition, there is no restriction | limiting in the addition rate of the aqueous medium after completion | finish of phase inversion.

  The amount of the aqueous medium used is preferably 100 to 2000 parts by weight, more preferably 150 to 100 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A) from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step. 1500 parts by weight, more preferably 150 to 500 parts by weight. The solid content concentration is preferably 7 to 50% by weight, more preferably 10 to 40% by weight, still more preferably 20 to 40% by weight, from the viewpoint of the stability and ease of handling of the obtained resin particle dispersion. More preferably, it is 25 to 35% by weight. 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 containing the obtained resin particles (A) is preferably from 0.02 to 2 μm, more preferably from the viewpoint of obtaining a high-image toner. It is 02-1.5 micrometers, More preferably, it is 0.05-1 micrometer, More preferably, it is 0.05-0.5 micrometer. 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 coefficient of variation (CV value) (%) of the particle size distribution of the resin particles is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, and still more preferably, from the viewpoint of obtaining a high-image toner. Is 28% or less. 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 median particle size (μm)] × 100

(Release agent particles)
The release agent particles of the present invention contain a wax and a polyester resin (b) having a softening point of 75 to 105 ° C., and the weight ratio of the wax to the polyester resin (b) is 95/5 to 55/45. is there.
The weight ratio of the wax and the polyester resin (b) is 95/5 to 55/45 from the viewpoint of improving the low-temperature fixability by maintaining releasability and from the viewpoint of emulsification and cohesiveness of the polyester resin particles. Preferably it is 95 / 5-60 / 40, More preferably, it is 95 / 5-70 / 30, More preferably, it is 95 / 5-80 / 20.

<Wax>
As the wax used in the present invention, mineral / petroleum wax, vegetable wax, animal wax, synthetic wax and the like can be used. Among these, from the viewpoint of improving the low-temperature fixability of the toner, mineral / petroleum waxes and vegetable waxes are preferable, and mineral / petroleum waxes are more preferable.

Examples of the mineral / petroleum wax include paraffin wax and montan wax. Among them, paraffin wax is preferable from the viewpoint of improving the low-temperature fixability of the toner and maintaining good storage stability.
Examples of plant waxes include carnauba wax, rice wax, and candelilla wax.
Animal waxes include beeswax and the like.
Examples of the synthetic wax include polyolefin wax, silicone wax, fatty acid amides, Fischer-Tropsch wax and the like. Specific examples of the polyolefin wax include low molecular weight polyethylene, low molecular weight polypropylene, and polybutene. Specific examples of the silicone wax include silicones having a softening point and softening by heating. Specific examples of fatty acid amides include oleic acid amide and stearic acid amide.
These release agents can be used alone or in combination of two or more.

The melting point of the wax is preferably 60 to 100 ° C., more preferably 50 to 89 ° C., more preferably 55 to 80 ° C., and still more preferably 60 ° C. to 60 ° C. from the viewpoints of low-temperature fixability, storage stability, and chargeability of the toner. 77 ° C, more preferably 62-73 ° C.
Further, the melting point of the wax has an absolute value of a difference of 8 from the softening point of the polyester resin (b) from the viewpoint of obtaining a release agent particle having a small particle size and a sharp particle size distribution and from the viewpoint of improving the heat resistant storage stability of the toner. It is -24 degreeC, More preferably, it is 16-24 degreeC. From the viewpoint of expanding the fixing temperature range and improving the fixability, it is preferably lower than the softening point of the polyester resin (b).
The melting point of the wax is determined by the method described in the examples. When two or more kinds of waxes are used in combination, the melting point of the wax having the largest content in the wax contained in the resulting toner is the melting point of the wax in the present invention. Let the average value of melting | fusing point be melting | fusing point of the wax in this invention.
The amount of the wax used is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the resin in the toner, from the viewpoint of toner releasability and chargeability.

<Polyester resin (b)>
The softening point of the polyester resin (b) is from 75 to 105 ° C., preferably from 78 to 102 ° C., more preferably from 82 to 102 ° C., from the viewpoint of obtaining fine release agent particles and improving the heat-resistant storage stability of the toner. 100 ° C., more preferably 90 to 99 ° C.
In the present invention, the polyester resin (b) is preferably amorphous, that is, a polyester having the above-mentioned crystallinity index of more than 1.4 or less than 0.6, preferably from the viewpoint of low-temperature fixability of the toner. Is less than 0.6 or more than 1.4 and 4 or less, more preferably less than 0.6 or 1.5 or more and 4 or less, more preferably less than 0.6 or 1.5 or more and 3 or less, more preferably 0.6. Less than or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined depending on the type and ratio of raw material monomers, production conditions (eg, reaction temperature, reaction time, cooling rate), and the like.
The polyester resin (b) is preferably an amorphous polyester having an acid group at the molecular end. Examples of the acid group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid. Among these, a carboxyl group is preferable from the viewpoint of promoting emulsification of the polyester.

The polyester resin (b) can be produced by a polycondensation reaction between an acid component and an alcohol component in the same manner as the polyester resin (a).
Examples of the acid component include dicarboxylic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, a trivalent or higher polyvalent carboxylic acid, and acid anhydrides thereof Alkyl (C1-C3) ester etc. are mentioned, Among these, dicarboxylic acid is preferable.
Examples of the dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, and cyclohexanedicarboxylic acid. Among these, fumaric acid and adipic acid are preferable. Fumaric acid is more preferable.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and the like. Among these, trimellitic acid and acid anhydride thereof from the viewpoint of offset resistance. Things are preferred.
These acid components can be used alone or in combination of two or more.
The polyester resin (b) uses an acid component containing a trivalent or higher polyvalent carboxylic acid and an acid anhydride or an alkyl ester thereof, preferably trimellitic acid or an anhydride thereof from the viewpoint of offset resistance of the toner. It is preferable to use at least one amorphous polyester obtained in this manner.

As an alcohol component, the thing similar to the said alcohol component used for the polyester resin (a) is mentioned. Among these, from the viewpoint of obtaining amorphous polyester, aromatic diols are preferable, and polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxy). More preferred are alkylene (carbon number 2-3) oxide adducts (average number of added moles 1-16) of bisphenol A such as phenyl) propane.
These alcohol components can be used alone or in combination of two or more.

The glass transition point of the polyester resin (b) is preferably 40 to 80 ° C., more preferably 45 to 70 ° C., and further preferably 50 to 60 ° C., from the viewpoint of toner durability, low-temperature fixability and storage stability. is there.
In addition, when using 2 or more types of polyester resin (b) mixed, the glass transition point and the softening point were obtained by the method of an Example description as a mixture of 2 or more types of polyester resins (b), respectively. Value.

The number average molecular weight of the polyester resin (b) is preferably 1,000 to 50,000, more preferably 1,000 to 10,000, and still more preferably, from the viewpoints of toner durability, low-temperature fixability and storage stability. Is 2,000 to 8,000.
The acid value of the polyester resin (b) is preferably 10 to 40 mgKOH / g, more preferably 15 to 35 mgKOH / g, and still more preferably, from the viewpoint of improving the emulsifiability of the resin in an aqueous medium and the heat resistant storage stability of the toner. 15-19 mg KOH / g.

<Manufacture of release agent particles>
The release agent particles used in the present invention are preferably obtained by dispersing a mixture obtained by melt-mixing a wax and a polyester resin (b) in an aqueous medium.

  First, the wax and the polyester resin (b) are melt-mixed at a temperature equal to or higher than the glass transition temperature of the polyester resin (b). The melt mixing method includes a method of melt-mixing only the wax and the polyester resin (b), a method of dissolving and mixing in an organic solvent at a temperature equal to or higher than the glass transition temperature of the polyester resin (b), while melting in an aqueous medium. The method of mixing is mentioned. Among these, from the viewpoint of ease of dispersion, uniform melt mixing, and suppression of reduction in heat-resistant storage stability due to residual solvent, a method of mixing while melting in an aqueous medium is preferred, and an aqueous medium containing a surfactant A method of mixing while melting in the inside is more preferable.

Next, the molten mixture of the release agent obtained by melt mixing is dispersed in an aqueous medium to obtain release agent particles. The release agent is preferably dispersed by dispersing the release agent and the aqueous medium at a temperature equal to or higher than the melting point of the release agent in the presence of a surfactant. As the disperser to be used, a homogenizer, an ultrasonic disperser or the like is preferable.
The aqueous medium used in this step is preferably the one exemplified as used when obtaining the resin particles (A), preferably water-based, and from the viewpoint of obtaining stable particles, The water content is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably substantially 100% by weight. The water used is preferably deionized water or distilled water.

As the surfactant used at the time of dispersion, an anionic surfactant is preferable because the dispersion stability of the release agent particles is maintained and the particle size control by aggregation is easy.
Examples of the anionic surfactant include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, polycarboxylate, and dipotassium alkenyl succinate. Acid salts and dipotassium alkenyl succinate are preferred.
As polycarboxylic acid, sodium polyacrylate, sodium polymaleate, and copolymers thereof are preferable, and sodium acrylate-sodium maleate copolymer is particularly preferable.
In the case of using the surfactant, the amount used is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the release agent, from the viewpoint of aggregation at the time of toner preparation and chargeability of the obtained toner. Preferably it is 0.1-5 weight part.

The volume median particle size of the release agent particles is preferably 0.1 to 1 μm, more preferably 0.1 to 0.7 μm, and still more preferably 0.1 to 0.1 μm, from the viewpoint of preventing toner chargeability and hot offset. 0.5 μm.
The CV value of the obtained release agent particles is preferably 15 to 50%, more preferably 15 to 40%, and still more preferably 15 to 35%, from the viewpoint of toner chargeability.
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 median particle size (μm)] × 100

[Flocculant]
In the present invention, an aggregating agent is used in order to obtain aggregated particles efficiently.
As the aggregating agent, a quaternary salt cationic surfactant, an organic aggregating agent such as polyethyleneimine; an inorganic aggregating agent such as 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 and calcium nitrate, and inorganic metal salt polymers such as polyaluminum chloride and polyaluminum hydroxide. Examples of the inorganic ammonium salt include ammonium sulfate, ammonium chloride, ammonium nitrate and the like, and ammonium sulfate is more preferable.

(Resin particles (B))
The resin particles (B) used in the present invention contain a polyester resin (c) from the viewpoint of storage stability and chargeability of the toner.
The glass transition point of the resin particle (B) is appropriately determined depending on the glass transition point of the resin such as the polyester resin (c) constituting the resin particle (B) and the kind and amount of the additive. From the viewpoint of low-temperature fixability and storage stability, it is preferably 55 ° C. or higher, more preferably 55 to 75 ° C., still more preferably 55 to 70 ° C., still more preferably 55 to 65 ° C.

<Polyester resin (c)>
In the present invention, the polyester resin (c) is preferably amorphous, that is, a polyester having the above-mentioned crystallinity index exceeding 1.4 or less than 0.6, preferably from the viewpoint of low-temperature fixability of the toner. Is less than 0.6 or more than 1.4 and 4 or less, more preferably less than 0.6 or 1.5 or more and 4 or less, more preferably less than 0.6 or 1.5 or more and 3 or less, more preferably 0.6. Less than or 1.5 or more and 2 or less. The crystallinity index can be appropriately determined depending on the type and ratio of raw material monomers, production conditions (eg, reaction temperature, reaction time, cooling rate), and the like.
The polyester resin (c) is preferably an amorphous polyester having an acid group at the molecular end. Examples of the acid group include a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid. Among these, a carboxyl group is preferable from the viewpoint of promoting emulsification of the polyester.

The polyester resin (c) can be produced by subjecting an acid component and an alcohol component to a polycondensation reaction in the same manner as the polyester resin (a).
Examples of the acid component include dicarboxylic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, a trivalent or higher polyvalent carboxylic acid, and acid anhydrides thereof Alkyl (C1-C3) ester etc. are mentioned, Among these, dicarboxylic acid is preferable.
Examples of the dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, succinic acid, and cyclohexanedicarboxylic acid. Among these, terephthalic acid is preferable.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and the like. Among these, trimellitic acid and acid anhydride thereof from the viewpoint of offset resistance. Things are preferred.
These acid components can be used alone or in combination of two or more.
The polyester resin (c) uses an acid component containing a trivalent or higher polyvalent carboxylic acid and an acid anhydride or an alkyl ester thereof, preferably trimellitic acid or an anhydride thereof from the viewpoint of offset resistance of the toner. It is preferable to use at least one amorphous polyester obtained in this manner.

As an alcohol component, the thing similar to the said alcohol component used for the polyester resin (a) is mentioned. Among these, from the viewpoint of obtaining amorphous polyester, aromatic diols are preferable, and polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxy). More preferred are alkylene (carbon number 2-3) oxide adducts (average number of added moles 1-16) of bisphenol A such as phenyl) propane.
These alcohol components can be used alone or in combination of two or more.

The glass transition point of the polyester resin (c) is preferably 55 to 75 ° C., more preferably 55 to 70 ° C., and still more preferably 58 to 68 ° C. from the viewpoint of toner durability, low-temperature fixability and storage stability. is there.
The softening point of the polyester resin (c) is preferably 75 to 105 ° C., more preferably 78 to 100 ° C., and more preferably 80 to 80 ° C. from the viewpoint of toner durability, low-temperature fixability and storage stability. It is 99 degreeC, More preferably, it is 82-98 degreeC.
In addition, when using 2 or more types of polyester resin (c) in mixture, the glass transition point and the softening point were obtained by the method of an Example description as a mixture of 2 or more types of polyester resins (c), respectively. Value.

The number average molecular weight of the polyester resin (c) is preferably 1,000 to 50,000, more preferably 1,000 to 10,000, and still more preferably, from the viewpoints of toner durability, low-temperature fixability and storage stability. Is 2,000 to 8,000.
The acid value of the polyester resin (c) is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 35 mgKOH / g, from the viewpoint of emulsification in the aqueous medium of the resin.

The content of the polyester resin (c) in the resin particles (B) is preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight from the viewpoint of storage stability and chargeability of the toner. Above, more preferably 95% by weight or more, still more preferably substantially 100% by weight.
In addition to the polyester resin (c), the resin particles (B) may contain a known resin that is usually used for toner, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, or a polyurethane.
The resin particles (B) are obtained by the same method as the method for producing the resin particles (A) described above, and the same alkaline aqueous solution, surfactant and aqueous medium can be suitably used.

  In addition, in this invention, what modified | denatured each of polyester resin (a), (b) and (c) can be used in the range which does not impair the effect. Examples of the method for modifying the polyester include grafting 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. Examples thereof include a method of forming a block and a method of forming a composite resin having two or more resin units including a polyester unit.

Next, each step in the method for producing an electrophotographic toner of the present invention will be described.
[Step (1)]
In the step (1), the resin particles (A) containing a resin containing 90% by weight or more of the polyester resin (a), the wax and the polyester resin (b) having a softening point of 75 to 105 ° C. are in a weight ratio (wax / Polyester resin (b)) is a step of obtaining aggregated particles (1) by mixing release agent particles contained in 95/5 to 55/45 and an aggregating agent in an aqueous medium.

There is no restriction | limiting in order of mixing, You may add any in order and may add simultaneously.
The temperature of the mixed dispersion at the time of mixing is preferably 0 to 40 ° C. from the viewpoint of aggregation control.

The amount of the resin particles (A) used is preferably 10 to 40 parts by weight, more preferably 20 to 30 parts by weight in the dispersion of the aggregated particles (1). The content of the aqueous medium is preferably 60 to 90 parts by weight, more preferably 70 to 80 parts by weight in the dispersion of the aggregated particles (1).
When the resin particles (A) contain a colorant, the content of the colorant in the resin particles (A) is based on 100 parts by weight of the resin constituting the resin particles (A) from the viewpoint of image density. The amount is preferably 1 to 20 parts by weight, more preferably 3 to 15 parts by weight.

  The amount of the release agent particles used in the step (1) is preferably 1 to 20 parts by weight, more preferably 100 parts by weight with respect to a total of 100 parts by weight of the resin and the colorant, from the viewpoint of toner releasability and chargeability. Is 2 to 15 parts by weight. As described above, the release agent particles are preferably obtained by dispersing a mixture obtained by melt-mixing the wax and the polyester resin (b) in an aqueous medium.

  In this step, particles containing a colorant may be mixed, or resin particles other than the resin particles (A) may be mixed. The resin particles other than the resin particles (A) are preferably resin particles containing the above-mentioned amorphous polyester from the viewpoint of improving the storage stability of the toner, and resin particles having the same composition as the resin particles (B). More preferred.

Next, the particles in the mixed dispersion are aggregated to obtain a dispersion of aggregated particles. In the present invention, the above-mentioned flocculant is added in order to efficiently perform the aggregation.
The use amount of the flocculant is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and further preferably 30 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A), from the viewpoint of toner charging properties. From the viewpoint of the cohesiveness of the resin particles, it is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and further preferably 5 parts by weight or more. In consideration of the above points, the amount of the monovalent salt used is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight with respect to 100 parts by weight of the resin constituting the resin particles (A). More preferably, it is 5-30 weight part.

  As an aggregating method, it is preferable to add the aggregating agent as an aqueous solution dropwise to a container containing the 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 aggregation control and shortening of toner production time, the dropping time of the aggregating agent is preferably 1 to 120 minutes. The dropping temperature is preferably 0 to 40 ° C. from the viewpoint of controlling aggregation.

  The volume-median particle size of the obtained aggregated particles is preferably 1 to 10 μm, more preferably 2 to 9 μm, still more preferably 3 to 6 μm, from the viewpoints of reducing the particle size of the toner and stabilizing the charge amount. . The CV value is preferably 30% or less, more preferably 28% or less, and still more preferably 25% or less.

[Step (2)]
Step (2) is a step of obtaining aggregated particles (2) by mixing aggregated particles (1) with resin particles (B) containing polyester resin (c) to be a shell.

In this step, first, a dispersion of resin particles (B) containing the polyester resin (c) (hereinafter also referred to as “resin particle (B) dispersion”) is prepared, and then the resin particles (B) are dispersed. It is preferable to add the liquid to the dispersion liquid of the aggregated particles (1) obtained in the step (1) to adhere the resin particles (B) to the aggregated particles (1) to obtain the aggregated particles (2).
Aggregated particles (2) preferably have a structure in which resin particles (B) are attached around aggregated particles (1).
Further, from the viewpoint of more uniformly attaching the resin particles (B) to the aggregated particles, the aqueous particles may be diluted by adding an aqueous medium to the aggregated particle (1) dispersion before adding the resin particle (B) dispersion. preferable.
When the resin particle (B) dispersion is added, the aggregating agent may be further added in order to efficiently attach the resin particles (B) to the agglomerated particles (1).
As a method for adding the resin particle (B) dispersion, a method of adding the resin particle (B) dispersion while gradually raising the temperature of the aggregated particle (1) dispersion, a flocculant and the resin particle (B) dispersion And the like, and the method of alternately adding the flocculant and the resin particle (B) dispersion are preferred. According to such a method, it is possible to prevent a decrease in the cohesiveness of the aggregated particles (1) and the resin particles (B). Among these, the method of adding the resin particle (B) dispersion while gradually increasing the temperature of the aggregated particle (1) dispersion is preferable from the viewpoint of toner productivity and manufacturing simplicity.

In this step, the temperature in the system at the time of addition and / or after the addition of the resin particles (B) is less than the melting point of the release agent and not less than 10 ° C. lower than the glass transition point of the polyester resin (c). Hold at temperature. Although the temperature at the time of addition of the resin particles (B) may not belong to the above range, in that case, the temperature after the addition is preferably within the above range.
By setting the temperature at the time of addition of the resin particles (B) to be lower than the melting point of the release agent, the low-temperature fixability and storage stability of the obtained toner can be improved, and the chargeability of the toner can be improved. The reason for this is not clear, but it is also considered that since the fusion of the aggregated particles (2) hardly occurs, the generation of coarse particles is suppressed and the crystallinity of the release agent can be maintained.
Moreover, when it is desired to promote the fusion of the resin particles (B), the fusion is promoted by maintaining the temperature at the time of addition at a temperature of 10 ° C. or lower than the glass transition point of the polyester resin (c). be able to.

  The addition amount of the resin particles (B) is a weight ratio of the resin particles (B) to the resin particles (A) (resin particles (B) / The amount of the resin particles (A)) is preferably 0.3 to 1.5, more preferably 0.3 to 1.0, and still more preferably 0.35 to 0.75.

  The resin particle (B) dispersion may be added continuously over a certain period of time, may be added at once, or may be added in multiple portions, but the resin particles (B) From the viewpoint of facilitating selective adhesion to the agglomerated particles (1), it is preferable to add them continuously over a certain period of time or to divide them several times, and in particular, promote selective adhesion. It is more preferable to add continuously over a certain period of time from the viewpoint of improving the efficiency of production and manufacturing. The addition time in the case of continuous addition is preferably 1 to 10 hours, more preferably 3 to 8 from the viewpoint of obtaining particles having a core-shell structure with no variation among the particles and shortening the production time in the next step. It's time.

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.
As the particle size for stopping the aggregation, the volume median particle size is preferably 1 to 10 μm, more preferably 2 to 8 μm, still more preferably 3 to 7 μm, and further preferably 4 to 6 μm.
Methods for stopping the aggregation include a method of cooling the dispersion and a method of adding an aggregation terminator. From the viewpoint of reliably preventing unnecessary aggregation, the aggregation is stopped by adding an aggregation terminator. The method of making it preferable is.
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.
The addition amount of the aggregation stopper is preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the total resin in the system, from the viewpoint of reducing the aggregation stopping property and the residual of the aggregation stopper in the toner. Preferably it is 0.1-10 weight part, More preferably, it is 0.1-8 weight part. The aggregation terminator may be added in any form, but is preferably added in an aqueous solution from the viewpoint of productivity.

[Step (3)]
Step (3) is a step of obtaining core-shell particles by fusing the particles constituting the aggregated particles (2).

In this step, the dispersion liquid containing the agglomerated particles (2) obtained in the step (2) is used as the particles constituting the agglomerated particles (2), that is, the resin particles (A), the resin particles (B), and the release agent. The core-shell particles are formed by maintaining the temperature at which the particles or the like are fused between the particles constituting the aggregated particles.
The temperature maintained for fusing is preferably less than the melting point of the release agent and from a polyester resin (from the viewpoint of heat-resistant storage stability of the toner and suppression of toner scattering in a printer such as a printer) It is kept at a temperature 10 ° C. or more lower than the glass transition point of c).
In addition, when adjusting to this temperature range when adding resin particle (B), it is not necessary to hold | maintain in this temperature range after addition. However, when it is necessary to control the particle size and shape, the addition is performed at a temperature lower than 10 ° C. below the glass transition point of the polyester resin (c), and after the addition, the temperature is set to a temperature of 10 ° C. lower than the glass transition point. It is preferable to hold it.

The holding temperature after the addition of the resin particles (B) is less than the melting point of the release agent, preferably less than 5 ° C lower than the melting point of the release agent, more preferably less than 10 ° C lower than the melting point of the release agent. By doing so, the chargeability of the toner can be improved.
Moreover, the holding temperature after completion | finish of addition is 10 degreeC or more lower than the glass transition point of a polyester resin (c), Preferably it is 5 degreeC or more lower than the said glass transition point, More preferably, it is 2 degreeC lower than the said glass transition point. By setting the temperature or higher, the fusing property, the storage stability of the toner, the charging property, and the toner productivity can be improved.
By satisfying these conditions, the release agent that exhibits high fixability at low temperatures can be maintained in a crystalline state, and the toner storage stability and exposure of the release agent to the toner surface can be reduced. Thus, it is considered that the particles constituting the shell portion can be uniformly fused, and as a result, it is possible to obtain a toner having both good low-temperature fixability, chargeability and storage stability.
Furthermore, from the viewpoint of fusing property, toner storage stability, chargeability, and toner productivity, in this step, it is preferable to hold at a temperature of 5 ° C. lower than the glass transition point of the resin particles (B), It is more preferable to hold at a temperature of 2 ° C. or higher than the glass transition point of the resin particles (B).
In view of the above points, the holding temperature in the step (3) is preferably 58 to 69 ° C, more preferably 59 to 67 ° C, and further preferably 60 to 64 ° C.
The holding time in this step is preferably 1 to 24 hours, more preferably 1 to 12 hours, and further preferably 2 to 6 hours, from the viewpoints of particle fusing property, storage stability, chargeability and toner productivity. .

  In this step, the circularity of the core-shell particles contained in the finally obtained dispersion of core-shell particles is 0.950 to from the viewpoint of improving toner storage stability and reducing toner scattering. 0.980, preferably 0.950 to 0.970, more preferably 0.955 to 0.965. The circularity of the toner particles is a value obtained by a ratio of the circumference of the circle equal to the projected area / the circumference of the projected image. The more circular the particles are, the closer the circularity is to 1. .

  The volume-median particle size of the core-shell particles in the dispersion of the core-shell particles is preferably 2 to 10 μm, more preferably 2 to 8 μm, more preferably 2 to 7 μm, from the viewpoint of improving the image quality of the toner. Preferably it is 3-8 micrometers, More preferably, it is 4-6 micrometers.

[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 core-shell particles.
Since the core-shell 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. In order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform washing with an acid in order to remove metal ions on the toner surface. Moreover, since it is preferable to remove the added nonionic surfactant, it is preferable to wash with an aqueous solution below the cloud point of the nonionic surfactant. The washing is preferably performed a plurality of times.
Next, it is preferable to perform drying. As the drying method, a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method or the like is preferable. The water content after drying is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of reducing the amount of toner scattered and charging properties.

[Electrostatic latent image developing toner]
(toner)
The toner particles obtained by drying or the like can be used as the toner as they are, but it is preferable to use the toner particle surface treated as described below as a toner for developing an electrostatic latent image.
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 low-temperature fixability of the toner. The glass transition point is preferably 30 to 80 ° C., more preferably 40 to 70 ° C. from the viewpoints of low-temperature fixability, durability, and storage stability.
The circularity of the toner is preferably 0.950 to 0.980, more preferably 0.955 to 0.970, and still more preferably 0.955 to 0, from the viewpoints of storage stability, chargeability, and cleaning properties of the toner. .965.
The toner obtained by the method of the present invention has a core-shell structure, and the polyester resin (c) is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, and still more preferably 90 to 100% by weight in the shell part. %contains.
The volume median particle size of the toner 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, from the viewpoint of high image quality and productivity of the toner.
The CV value of the toner is preferably 30% or less, more preferably 27% or less, still more preferably 25% or less, and further preferably 22% or less, from the viewpoint of high image quality and productivity.

(External additive)
In the toner for developing an electrostatic latent image 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 arbitrary fine particles such as polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Of these, hydrophobic silica is preferred.
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 weight, more preferably 100 parts by weight of the toner particles before the treatment with the external additive. 1 to 3.5 parts by weight, more preferably 1 to 3 parts by weight.
The toner for developing an electrostatic latent image obtained by the present invention can be used as a one-component developer or mixed with a carrier and used as a two-component developer.

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)).

[Softening point of polyester, glass transition point, melting point of release agent]
(1) Softening point of polyester Using a flow tester (manufactured by Shimadzu Corporation, trade name: CFT-500D), while heating a 1 g sample at a heating rate of 6 ° C./min, A load was applied and extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. The amount of flow tester drop by the flow tester was plotted against the temperature, and the temperature at which half the sample flowed out was taken as the softening point.
(2) Polyester glass transition point, release agent melting point Using a differential scanning calorimeter (manufactured by ParkinElmer, trade name: Pyris 6 DSC), the temperature was raised to 200 ° C., and the temperature was lowered at a rate of 50 ° C./min. The sample cooled to 0 ° C. was measured at a heating rate of 10 ° C./min. Among the observed endothermic peaks, the temperature of the peak having the maximum peak area was defined as the maximum endothermic peak temperature. In the mold release agent, the peak temperature was the melting point. In the case of an amorphous polyester, when an endothermic peak is observed, the temperature of the peak is measured, and when a step is observed without a peak being observed, the tangent indicating the maximum slope of the curve of the step and the step The glass transition point was defined as the temperature at the intersection with the base line extension line on the high temperature side.

[Solid content concentration of resin particle dispersion and release agent particle dispersion]
Using an infrared moisture meter (trade name: FD-230, manufactured by Ketto Scientific Laboratory Co., Ltd.), 5 g of the resin particle dispersion was dried at 150 ° C. and measurement mode 96 (monitoring time 2.5 minutes / variation range 0. 05%), the moisture percentage was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (% by weight) = 100-M
M: moisture (%) = [(W−W0) / W] × 100
W: Sample weight before measurement (initial sample weight)
W0: Sample weight after measurement (absolute dry weight)

[Volume median particle size of resin particles and release agent particles]
(1) Measuring apparatus: Laser scattering type particle size measuring instrument (trade name: LA-920, manufactured by Horiba, Ltd.)
(2) Measurement conditions: Distilled water is added to the measurement cell, and the volume-median particle size (D ₅₀ ) is measured at a temperature at which the absorbance is in an appropriate range. The particle size distribution is represented by a CV value (standard deviation of particle size distribution / volume median particle size (D ₅₀ ) × 100) (%).

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution of Aggregated Particles, Core Shell Particles]
The volume median particle size of the aggregated particles and core-shell particles was measured as follows.
Measuring instrument: 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)
Measurement conditions: 30,000 particles after adjusting the particle size of 30,000 particles to a concentration that can be measured in 20 seconds by adding a sample dispersion containing aggregated particles and core-shell particles to 100 mL of the electrolyte. The volume-median particle size (D ₅₀ ) was determined from the particle size distribution.
Further, the CV value (%) as a particle size distribution was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution / volume median particle size (D ₅₀ )) × 100

[Volume Median Particle Size (D ₅₀ ) and Particle Size Distribution of Toner (Particles)]
The volume median particle size of the toner (particles) was measured as follows.
The measuring instrument, aperture diameter, analysis software, and electrolyte solution were the same as the volume median particle diameter of the aggregated particles.
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 weight.
-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. The volume-median particle size (D ₅₀ ) was determined from
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: ML5400, manufactured by Oki Data Co., Ltd.) on high-quality paper (Fuji Xerox Co., Ltd., J paper A4 size), the toner adhesion amount on the paper is 0.42 to 0.48 mg. A solid image of / cm ² 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 a variable temperature fixing device was prepared. The temperature of the fixing device was set to 100 ° C., and fixing was performed at a speed of 1.5 seconds per sheet in the A4 longitudinal direction to obtain a printed matter.
In the same manner, the temperature of the fixing device was increased by 5 ° C., and the fixing was performed to obtain a printed matter.
A 500 g weight is applied to the margin at the top of the printed image, after lightly pasting a piece of mending tape (product name: Scotch mending tape 810, width 18 mm) cut to a length of 50 mm. It was loaded and pressed once and again 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 a speed of 10 mm / second to obtain a printed matter after the tape was peeled off. 30 sheets of high quality paper (Oki Data Co., Ltd., Excellent White Paper A4 size) is placed under the printed material before and after the tape is applied, and the reflected image density of the fixed image portion before and after the tape is applied to each printed material. , Measured using a colorimeter (GretagMacbeth, trade name: SpectroEye, light emission condition: standard light source D ₅₀ , observation field of view 2 °, density standard DINNB, absolute white standard) Calculated.
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]
10 g of toner was put into a cylindrical polypropylene bottle (made by Nikko Co., Ltd.) having an internal volume of 20 ml, and left in an open state in an environment of a temperature of 50 ° C. and a relative humidity of 40 RH% for 12 hours. After standing, set three sieves in the order of 250 μm upper opening, 150 μm middle opening and 75 μm lower opening on a powder tester (made by Hosokawa Micron Corporation), and put 2 g of toner on it for 60 seconds. Vibration was performed, and the weight of toner remaining on each sieve was measured. The measured toner weight was applied to the following equation to calculate the degree of aggregation [%].
Aggregation degree [%] = a + b + c
a = (weight of residual toner on upper stage) / 2 [g] × 100
b = (middle stage residual toner weight) / 2 [g] × 100 × (3/5)
c = (lower stage residual toner weight) / 2 [g] × 100 × (1/5)
The smaller the degree of aggregation, the better the toner is in heat resistant storage stability. The storage stability of the toner was evaluated according to the following criteria.
A: The degree of aggregation is less than 2% B: The degree of aggregation is 2% or more and less than 10% C: The degree of aggregation is 10% or more and less than 20% D: The degree of aggregation is 20% or more

[Production of polyester resin]
Production Example 1
(Production of polyester resin (A) (amorphous polyester))
8320 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 80 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 1592 g of terephthalic acid and 32 g of dibutyltin oxide was placed in a four-necked flask, and stirred under a nitrogen atmosphere at normal pressure (101.3 kPa) and 230 ° C. for 5 hours, and further under reduced pressure (8.3 kPa), and stirring was continued for 2 hours. The reaction mixture was returned to normal pressure, cooled to 210 ° C., added with 1672 g of fumaric acid and 8 g of hydroquinone, stirred for 5 hours, and further stirred under reduced pressure, and the softening point measured according to ASTM D36-86 was 110 ° C. Was reached to obtain a polyester resin (A).
The crystallinity index of the polyester resin (A) was 1.5, the softening point was 110 ° C., the glass transition point was 66 ° C., and the acid value was 24.4 mgKOH / g.

Production Example 2
(Production of polyester resin (B) (amorphous polyester))
4176 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 3881 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 2253 g of terephthalic acid, 322 g of dodecenyl succinic anhydride, 945 g of trimellitic anhydride and 15 g of dibutyltin oxide are placed in a four-necked flask and stirred at 220 ° C. under a nitrogen atmosphere, and the softening point measured according to ASTM D36-86 reaches 120 ° C. Then, it was cooled to obtain a polyester resin (B).
The polyester resin (B) had a crystallinity index of 1.6, a softening point of 121 ° C., a glass transition point of 65 ° C., and an acid value of 21.0 mgKOH / g.

Production Example 3
(Production of polyester resin (C) (amorphous polyester))
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (3802 g), fumaric acid (1197 g) and tert-butylcatechol (2.5 g) were placed in a four-necked flask and stirred under a nitrogen atmosphere. The temperature was raised to ° C., maintained for 1 hour, and then raised to 210 ° C. over 4 hours. Further, the pressure in the flask was lowered and maintained at 27.0 kPa for 1 hour to obtain a polyester resin (C).
Polyester resin (C) had a crystallinity index of 1.6, a softening point of 85 ° C., a glass transition point of 47 ° C., and an acid value of 27 mgKOH / g.

Production Example 4
(Production of polyester resin (D) (amorphous polyester))
4435 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1765 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 1492 g of fumaric acid, 542 g of trimellitic anhydride and 2.5 g of tert-butylcatechol were placed in a four-necked flask, heated to 180 ° C. with stirring in a nitrogen atmosphere, maintained for 1 hour, and then heated to 210 ° C. over 3 hours. . Further, the pressure in the flask was lowered and maintained at 27.0 kPa for 1 hour to obtain a polyester resin (D).
Polyester resin (D) had a crystallinity index of 1.5, a softening point of 98 ° C., a glass transition point of 57 ° C., and an acid value of 19 mgKOH / g.

Production Example 5
(Production of polyester resin (E) (amorphous polyester))
3500 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 3250 g of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 1114 g of fumaric acid, 282 g of adipic acid, 576 g of trimellitic anhydride and 2.5 g of tert-butylcatechol were placed in a four-necked flask, heated to 180 ° C. with stirring in a nitrogen atmosphere, maintained for 1 hour, and then 210 ° C. over 4 hours. The temperature was raised to. Further, the pressure in the flask was lowered and maintained at 27.0 kPa for 1 hour to obtain a polyester resin (E).
Polyester resin (E) had a crystallinity index of 1.6, a softening point of 84 ° C., a glass transition point of 47 ° C., and an acid value of 20 mgKOH / g.

[Production of resin particle dispersion]
Production Example 6
(Production of dispersion liquid (A1) of resin particles (A))
In a 2-liter stainless steel flask, 390.0 g of a polyester resin (A), 210.0 g of a polyester resin (B), 45.0 g of a copper phthalocyanine pigment (trade name: ECB-301, manufactured by Dainichi Seika Kogyo Co., Ltd.), Sodium dodecylbenzenesulfonate 15% by weight aqueous solution (trade name: Neoperex G-15, anionic surfactant), 40.0 g, polyoxyethylene oleyl ether (trade name, manufactured by Kao Corporation), trade name: Emulgen 430, nonionic surfactant) 6.0g, and 58.5% by weight potassium hydroxide aqueous solution 278.5g, with stirring, heated to 95 ° C to melt, mixed at 95 ° C for 2 hours A resin mixture was obtained.
Next, while maintaining the temperature of the system at 95 ° C., 1222 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, and 28 g of an oxazoline group-containing polymer aqueous solution (manufactured by Nippon Shokubai Co., Ltd., trade name: Epocross WS-700, nonvolatile content 25 wt%, acrylic main chain) was added while stirring at 25 ° C. Then, the temperature was raised to 95 ° C. and held at 95 ° C. for 1 hour. Next, the mixture was cooled to 25 ° C., and the obtained emulsion was passed through a 200 mesh (mesh opening 105 μm) wire mesh to obtain a dispersion (A1) of resin particles (A).
The solid content concentration of the dispersion (A1) was 31%, the volume median particle size (D ₅₀ ) of the resin particles (A) in the dispersion (A1) was 180 nm, and the CV value was 28%.

Production Example 7
(Production of dispersion (B1) of resin particles (B))
In a 2 liter stainless steel flask, 390.0 g of polyester resin (A), 210.0 g of polyester resin (B), 15% by weight aqueous solution of sodium dodecylbenzenesulfonate (previously Neoperex G-15) 20.0 g, polyoxyethylene (26 mol) oleyl ether (Emulgen 430) 6.0 g and 58.5% by weight potassium hydroxide aqueous solution 278.5 g were added, heated to 95 ° C. with stirring, melted, and mixed at 95 ° C. for 2 hours. A resin mixture was obtained.
Next, while maintaining the temperature of the system at 95 ° C., 1222 g of deionized water was added dropwise at a rate of 6 g / min while stirring to obtain an emulsion. Next, the mixture was cooled to 25 ° C., and the obtained emulsion was passed through a 200-mesh wire mesh to obtain a dispersion (B1) of resin particles (B).
The solid content concentration of the dispersion (B1) was 30%, the volume median particle size (D ₅₀ ) of the resin particles (B) in the dispersion (B1) was 141 nm, and the CV value was 24%.

[Production of release agent particle dispersion]
Production Example 8
(Production of release agent particle dispersion (A))
After dissolving 3.8 g of an aqueous solution of sodium acrylate-sodium maleate copolymer (trade name: Poise 521, effective concentration 40% by weight, manufactured by Kao Corporation) in 200 g of deionized water in a 1 liter beaker. To this, 5 g of polyester resin (C) and 45 g of paraffin wax HNP-9 (trade name, manufactured by Nippon Seiwa Co., Ltd., melting point 75 ° C.) are added, and the mixture is melted while maintaining the temperature at 90 to 95 ° C. Thus, a molten mixture in which the polyester resin and the paraffin wax were integrally melted was obtained.
The aqueous solution containing the obtained molten mixture was further subjected to a dispersion treatment for 30 minutes with an ultrasonic homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name: US-600T) while maintaining the temperature at 90 to 95 ° C. Then, ion-exchange water was added thereto to adjust the release agent solid content to 20% by weight to obtain a release agent particle dispersion (A).
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (A) was 430 nm, and the CV value was 26%.

Production Example 9
(Production of release agent particle dispersion (B))
In Production Example 8, a release agent particle dispersion (B) was obtained in the same manner as in Production Example 8 except that the polyester resin (D) was used instead of the polyester resin (C).
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (B) was 650 nm, and the CV value was 40%.

Production Example 10
(Production of release agent particle dispersion (C))
In Production Example 8, paraffin wax HNP-11 (trade name, manufactured by Nippon Seiwa Co., Ltd., melting point: 68 ° C.) was used in place of paraffin wax HNP-9 in the same manner as in Production Example 8, except for separation. A mold particle dispersion (C) was obtained.
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (C) was 540 nm, and the CV value was 35%.

Production Example 11
(Production of release agent particle dispersion (D))
In Production Example 8, a release agent particle dispersion (D) was obtained in the same manner as in Production Example 8 except that the polyester resin (E) was used instead of the polyester resin (C).
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (D) was 580 nm, and the CV value was 38%.

Production Example 12
(Production of release agent particle dispersion (E))
In Production Example 8, 45 g of paraffin wax HNP-9 and 50 g of polyester resin (C) were used, and 50 g of paraffin wax HNP-9 was used. Instead of the aqueous solution of sodium acrylate-sodium maleate copolymer, an aqueous solution of dipotassium alkenyl succinate ( A release agent particle dispersion liquid (E) was obtained in the same manner as in Production Example 8, except that Kao Corporation, trade name: Latemul ASK, effective concentration 28%) was used.
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (E) was 330 nm, and the CV value was 22%.

Production Example 13
(Production of release agent particle dispersion (F))
A 20L Henschel mixer was prepared from a raw material consisting of 4550 g of polyester (A), 2450 g of polyester (B), 350 g of paraffin wax HNP-9, and 350 g of copper phthalocyanine pigment (trade name: ECB-301, manufactured by Dainichi Seika Kogyo Co., Ltd.). After mixing for 3 minutes at a stirring speed of 1500 r / m, the resulting kneaded product is melt-kneaded using an open roll type continuous kneader (made by Nippon Coke Kogyo Co., Ltd., trade name: Needex). After cooling with a cooling belt, the mixture was roughly crushed with a mill having a 2 mm screen to obtain a kneaded product. The softening point was 110 ° C, the glass transition point was 62 ° C, and the acid value was 21 mgKOH / g.
Next, 660.0 g of the kneaded product and a 15% by weight aqueous solution of sodium dodecylbenzenesulfonate (trade name: Neoperex G-15, anionic surfactant) manufactured by Kao Corporation are placed in a 2 liter stainless steel flask. 0 g, polyoxyethylene oleyl ether (manufactured by Kao Corporation, trade name: Emulgen 430, nonionic surfactant) 6.0 g, and 58.5% by weight potassium hydroxide aqueous solution 278.5 g were added and stirred. The mixture was heated to 0 ° C., melted, and mixed at 95 ° C. for 2 hours to obtain a resin mixture.
Next, while maintaining the temperature of the system at 95 ° C., 1222 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, and 28 g of an oxazoline group-containing polymer aqueous solution (manufactured by Nippon Shokubai Co., Ltd., trade name: Epocross WS-700, nonvolatile content 25 wt%, acrylic main chain) was added while stirring at 25 ° C. Then, the temperature was raised to 95 ° C. and held at 95 ° C. for 1 hour. Next, it was cooled to 25 ° C., and the resulting emulsion was passed through a 200 mesh (mesh 105 μm) wire mesh to obtain a release agent particle dispersion (F).
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (F) was 163 nm, and the CV value was 28%.

Production Example 14
(Production of release agent particle dispersion (G))
In Production Example 8, a release agent particle dispersion (G) was produced in the same manner as in Production Example 8 except that the usage amounts of the polyester resin (C) and the paraffin wax HNP-9 were changed to 25 g and 25 g, respectively. Could not be sufficiently dispersed and some precipitates were generated, and fine emulsified particles could not be obtained.
The volume median particle size (D ₅₀ ) of the release agent particles in the release agent particle dispersion (G) was 1.2 μm, and the CV value was 85%.

Example 1
250 g of resin particle (A) dispersion (A1), 66 g of deionized water and 42 g of release agent particle dispersion (A) are placed in a 2-liter four-necked flask equipped with a dehydrating tube, a stirrer and a thermocouple. And mixed at 25 ° C. Next, while stirring at 25 ° C., an aqueous solution in which 20.9 g of ammonium sulfate was dissolved in 220 g of deionized water was added dropwise to this mixture over 30 minutes. Subsequently, the obtained mixed liquid was heated to 55 ° C. and held at 55 ° C. to obtain a dispersion containing aggregated particles (1) having a volume median particle size of 4.0 μm (step (1)).
Subsequently, a liquid mixture obtained by mixing 72 g of the dispersion liquid (B1) of the resin particles (B) and 22.5 g of deionized water was prepared in the dispersion liquid containing the obtained aggregated particles (1), and divided into three. They were added dropwise over 60 minutes each. Next, a mixture of 28 g of dispersion (A1) of resin particles (A) and 9.0 g of deionized water and an aqueous solution in which 1.5 g of ammonium sulfate was dissolved in 15 g of deionized water were simultaneously mixed for 60 minutes. It was dripped over. Then, the same liquid mixture and aqueous solution were prepared, and it was dripped over 60 minutes simultaneously. As a result, a dispersion liquid containing aggregated particles (2) having a volume median particle size of 5.0 μm was obtained (step (2)).
In a dispersion containing the obtained aggregated particles (2), 11.6 g of sodium polyoxyethylene lauryl ether sulfate (manufactured by Kao Corporation, trade name: Emar E27C, solid content: 28% by weight) and 450 g of deionized water, After adding the mixed aqueous solution, the temperature was raised to 70 ° C. over 2 hours and maintained for 2 hours to obtain core-shell particles having a volume median particle size of 5.0 μm (step (3)).
The obtained dispersion of core-shell particles was cooled to 25 ° C., filtered, dried and washed to obtain toner particles. To 100 parts by weight of the toner particles, hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd., trade name: RY50, number average particle size; 0.04 μm), 2.5 parts by weight, hydrophobic silica (manufactured by Cabot Corporation, product) Name: Cabo Seal TS720, number average particle size: 0.012 μm) 1.0 part by weight, 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 weight was externally added with a Henschel mixer and passed through a 150 mesh sieve to obtain an electrostatic latent image developing toner.

Examples 2 to 4 and Comparative Examples 1 to 3
In Example 1, a toner was obtained in the same manner as in Example 1 except that the kind of the dispersion (A1) of the resin particles (A) and / or the release agent particle dispersion was changed as shown in the table. It was.
Note that the toner of Comparative Example 3 had a large particle size as the release agent particles in the step (3), and therefore could not aggregate with the resin particles, and thus no toner was obtained.

  From Table 1, the toner for developing an electrostatic latent image of the example obtained by the method for producing the toner for developing an electrostatic latent image of the present invention is superior in low-temperature fixability and heat-resistant storage stability as compared with the toner of the comparative example. I understand.

  According to the production method of the present invention, it is possible to provide an electrostatic latent image developing toner excellent in low-temperature fixability and heat-resistant storage stability. The toner for developing an electrostatic latent image obtained by the present invention can be used as a one-component developer or mixed with a carrier and used as a two-component developer.

Claims (10)

A method for producing a toner for developing an electrostatic latent image, comprising the following steps (1) to (3):
Step (1): Resin particles (A) containing a resin containing 90% by weight or more of the polyester resin (a) , a wax having a melting point of 60 to 100 ° C., and a polyester resin (b) having a softening point of 75 to 105 ° C. The step of obtaining the aggregated particles (1) by mixing the release agent particles and the flocculant in a weight ratio (wax / polyester resin (b)) 95/5 to 70/30 in an aqueous medium. 2): The step of mixing the aggregated particles (1) with the resin particles (B) containing the polyester resin (c) serving as the shell to obtain the aggregated particles (2) Step (3): The aggregated particles (2) Process of obtaining core-shell particles by fusing constituent particles   The toner for developing an electrostatic latent image according to claim 1, comprising a step of dispersing a mixture obtained by melt-mixing the wax and the polyester resin (b) in an aqueous medium to obtain release agent particles. Method.   The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the wax is paraffin wax.   The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the acid value of the polyester resin (b) is 10 to 40 mg KOH / g.   The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 4, wherein the wax has a melting point of 60 to 100C.   The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the polyester resin (a) is an amorphous polyester.   The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 6, wherein the polyester resin (b) is an amorphous polyester.   The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein the resin particles (A) are colorant-containing resin particles containing a colorant. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 8, wherein an absolute value of a difference between a melting point of the wax and a softening point of the polyester resin (b) is 8 to 24 ° C.   An electrostatic latent image developing toner obtained by the production method according to claim 1.