JP5578037B2 - Method for producing liquid developer - Google Patents

Description

  The present invention relates to a method for producing a liquid developer.

Patent Document 1 discloses a method for producing a liquid developer in which toner particles are dispersed in an insulating liquid, wherein the insulating liquid includes at least a first liquid and a second liquid, The first liquid has a viscosity lower than that of the second liquid, and a wet pulverization step of pulverizing a toner material containing a colorant and a resin material in the first liquid to obtain a pulverized dispersion. And a method for producing a liquid developer, which includes a mixing step of mixing the pulverized material dispersion and the second liquid.
Patent Document 2 discloses a liquid developer having an insulating liquid containing a fatty acid monoester and disk-shaped toner particles mainly composed of a resin material.
Patent Document 3 discloses a method of forming a color image using a liquid developer in which flat toner particles are dispersed.
In Patent Document 4, the volume average particle diameter d50 is 0.5 to 5.0 μm and the flatness (the longest particle diameter in one particle / the shortest particle diameter in one particle) 1.5 to 30 in the medium liquid. A liquid developer is disclosed in which polymer fine particles having a flat shape are dispersed. Further, as a method for producing such flat polymer fine particles, a method is disclosed in which a spherical polymer fine particle dispersion is prepared and then the polymer fine particles are crushed and deformed in the dispersion.

JP 2007-41027 A JP 2009-58688 A JP 2002-365867 A JP-A-7-92742

  An object of the present invention is to provide a method for producing a liquid developer in which a liquid developer containing flat toner particles is easily produced.

In order to achieve the above object, the following invention is provided.
The invention according to claim 1
A crude particle preparing step of preparing crude particles containing a binder resin containing polyester and a solid plasticizer;
The crude particles and the insulating carrier liquid are mixed, and the crude particles are milled while controlling the average temperature of (Tg-5) ° C. to Tg ° C. with respect to the glass transition temperature Tg ° C. of the crude particles. Crushing step to obtain flat toner particles by crushing with,
Is a method for producing a liquid developer.
The invention according to claim 2
The method for producing a liquid developer according to claim 1, wherein the solid plasticizer is a polyester polyol.
The invention according to claim 3
3. The liquid development according to claim 1, wherein in the pulverization step, a mixing ratio of the coarse particles and the carrier liquid (a mass of the coarse particles / a mass of the carrier liquid) is set to 10/90 or more and 40/60 or less. It is a manufacturing method of an agent.
The invention according to claim 4
4. The method for producing a liquid developer according to claim 1, wherein a ball mill, a bead mill, or an attritor is used as a pulverizer for pulverizing the crude particles in the pulverization step. 5.
The invention according to claim 5
The coarse particle preparation step includes:
Kneading the binder resin containing the polyester and the solid plasticizer to obtain a kneaded product;
Crushing the kneaded product to obtain the crude particles;
5. The method for producing a liquid developer according to claim 1, comprising:

According to the first aspect of the present invention, compared to the case where spherical toner particles are produced in a carrier liquid and then the toner particles are crushed into a flat shape to produce a liquid developer, the toner particles are flat. Provided is a method for producing a liquid developer by which the liquid developer is easily produced.
According to the second aspect of the present invention, there is provided a method for producing a liquid developer capable of reliably obtaining flat toner particles as compared with the case where the crude particles do not contain polyester polyol as a solid plasticizer.
According to the invention of claim 3, the toner particles having a flat shape are compared with the case where the mass ratio of the coarse particles to the carrier liquid in the pulverization step (the mass of the coarse particles / the mass of the carrier liquid) is outside the above range. A method for producing a liquid developer is provided by which a liquid developer containing a liquid can be easily obtained.
According to the invention of claim 4, in the pulverization step, a liquid developer capable of obtaining flat toner particles by reliably pulverizing the coarse particles as compared with the case of using a pulverizer other than a ball mill, a bead mill, or an attritor. A manufacturing method is provided.
According to the invention according to claim 5, a manufacturing method in which the liquid developer containing flat toner particles is easily manufactured as compared with the case where the crude particles are manufactured by a method other than the method of pulverizing the kneaded product. Is provided.

4 is an electron micrograph showing flat toner particles obtained in an example.

  When image formation is performed using a liquid developer, in order to obtain a sufficient image density with a small amount of toner, for example, it is necessary to make the toner particles small, but a binder resin or the like that becomes toner particles is used. When toner particles are produced by mixing the kneaded product and a liquid such as a carrier liquid to pulverize the kneaded product, the toner particles are limited by the solid content concentration and viscosity at the time of pulverization. For example, a method of reducing the solid content concentration during pulverization to about 5% by mass or pulverizing using a low-viscosity carrier liquid is conceivable. However, when it is desired to increase the solid content concentration (toner particle concentration) of the developer. Requires a step of concentrating the developer after pulverization. In addition, when it is desired to use a carrier liquid with low viscosity and low viscosity, a step of replacing the carrier liquid after pulverization is necessary.

  On the other hand, when a liquid developer containing flat toner particles is used, the required area of the image can be obtained with a small amount because the area of the paper covered with the toner is larger than that of the spherical toner. However, it takes more man-hours to obtain a liquid developer containing flat toner particles than when producing a liquid developer containing spherical toner particles.

  The method for producing a liquid developer according to the present embodiment comprises a coarse particle preparation step of preparing coarse particles containing a binder resin containing polyester and a solid plasticizer, and the coarse particles and an insulating carrier liquid. A pulverizing step of obtaining flat toner particles by pulverizing the coarse particles by grinding force while controlling the average temperature of (Tg-5) ° C. or higher and Tg ° C. or lower with respect to the glass transition temperature Tg ° C. of the coarse particles. And having. According to such a method, a liquid developer containing flat toner particles is easily produced regardless of the type (viscosity) and solid content concentration of the carrier liquid.

[Rough particle preparation process]
A crude particle containing a binder resin containing polyester and a solid plasticizer is prepared. The coarse particles constitute flat toner particles contained in the liquid developer to be finally produced. The method for producing the coarse particles is not particularly limited, but from the viewpoint of simplifying the entire process, for example, a binder resin containing polyester and a solid plasticizer, and further, if necessary, a colorant and other additives are mixed. It is desirable to obtain it by kneading and then pulverizing.

The crude particles used in this embodiment are particles in the previous stage larger than the flat toner particles obtained by pulverization in the next pulverization step, and contain at least a binder resin containing polyester and a solid plasticizer. Configured. The coarse particles need not be spherical and may have irregularities on the surface.
From the viewpoint of more easily obtaining flat toner particles in the next pulverization step, the volume average particle size of the coarse particles is desirably 10 μm or more and 30 μm or less, and more desirably 15 μm or more and 20 μm or less. The volume average particle diameter of the crude particles is a value measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by BECKMAN COULTER).

-Binder resin-
As the binder resin constituting the coarse particles, a binder resin containing at least polyester is used. If polyester is used as the binder resin, a flat shape is easily obtained, which is advantageous. As polyester used by this embodiment, molecular weight is MW8000 or more and MW30000 or less, for example.
The coarse particles may contain other binder resin in addition to polyester. Examples of binder resins other than polyester include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-maleic anhydride. Examples of the copolymer include polyethylene, polypropylene, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, and paraffin wax.

The content of the polyester constituting the binder resin is preferably 80% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less, based on the total binder resin, from the viewpoint of improving pigment dispersibility. desirable.
Further, the total content of the binder resin contained in the crude particles is more preferably 50% by mass or more and 99% by mass or less with respect to the total mass of the crude particles from the viewpoint of improving pigment dispersibility.

-Solid plasticizer-
Solid plasticizers are those that plasticize binder resins, such as diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabiethyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate , Ethylene glycol tribenzoate, trimethylolethane tribenzoate, glyceride tribenzoate, pentaerythritol tetrabenzoate, sucrose octaacetate, tricyclohexyl citrate, N-cyclohexyl-p-toluenesulfonamide, triphenyl Examples include phosphate and polyester polyol.
Among these, polyester polyol is desirable from the viewpoint of obtaining flat toner particles.

  Here, “solid” means that the melting point is 40 ° C. or higher and is not compatible with the binder resin. The melting point of the solid plasticizer is 40 ° C. or higher and the fixing temperature or lower, but is preferably 40 ° C. or higher and 100 ° C. or lower, and more preferably 50 ° C. or higher and 90 ° C. or lower. The melting point of the solid plasticizer is a value obtained using a differential scanning calorimeter [manufactured by Mac Science: DSC3110, thermal analysis system 001] (hereinafter sometimes simply referred to as “DSC”).

The polyester polyol is formed by condensation of one or more polyhydric alcohols having 2 to 15 carbon atoms and one or more polycarboxylic acids having 2 to 14 carbon atoms.
Examples of suitable polyhydric alcohols include ethylene glycol, propylene glycol such as 1,2-propylene glycol and 1,3-propylene glycol, glycerol, pentaerythritol, trimethylolpropane, 1,4,6-octanetriol, butane Diol, pentanediol, hexanediol, dodecanediol, octanediol, chloropentanediol, glycerol monoallyl ether, glycerol monoethyl ether, diethylene glycol, 2-ethylhexanediol-1,4, cyclohexanediol-1,4,1,2 , 6-hexanetriol, 1,3,5-hexanetriol, 1,3-bis (2-hydroxyethoxy) propane and the like.

Examples of polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, maleic acid, dodecylmaleic acid, octadecenylmaleic acid, fumaric acid, aconic acid, trimellitic acid, Tricarballylic acid, 3,3′-thiodipropionic acid, succinic acid, adipic acid, malonic acid, glutaric acid, pimelic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid, 1,4-cyclohexadiene-1, 2-dicarboxylic acid, 3-methyl 3,5-cyclohexadiene-1,2-dicarboxylic acid, and the corresponding acid anhydrides, acid chlorides and acid esters, such as phthalic anhydride, phthaloyl chloride, and dimethyl esters of phthalic acid Etc.
The polycarboxylic acids are preferably aliphatic and alicyclic dicarboxylic acids containing 14 or fewer carbon atoms and aromatic dicarboxylic acids containing 14 or fewer carbon atoms.

  The content of the solid plasticizer is preferably 1% by mass or more and 30% by mass or less and more preferably 2% by mass or more and 10% by mass or less with respect to the total mass of the crude particles from the viewpoint of storage stability. desirable.

-Additives-
The crude particles serving as toner particles may contain additives such as a colorant, a release agent, and a charge control agent in addition to the binder resin and the solid plasticizer.

  As the colorant, known colorants are used, for example, magnetic powder such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, Phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 185, C.I. I. Pigment blue 15: 1, C.I. I. And CI Pigment Blue 15: 3

Release agents are animals, plants, minerals, synthetic raw materials, or coarse particles thereof, and are solid at room temperature.
Examples of the charge control agent include known charge control agents such as an azo metal complex compound, a metal complex compound of salicylic acid, and a resin type charge control agent containing a polar group.
Also, silica, titanium oxide, metatitanic acid, aluminum oxide, magnesium oxide, alumina, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, antimony trioxide, magnesium oxide, zirconium oxide, etc. These known external additives may be externally added.

  The method for obtaining the coarse particles is not particularly limited and may be prepared by reprecipitation. For example, the binder resin and the solid plasticizer, and further, if necessary, a colorant and other additives are mixed and kneaded. It is desirable to prepare a coarse particle (kneaded pulverized product) by previously pulverizing the product (kneaded product). Examples of the pulverizer used when the kneaded material containing the binder resin and the solid plasticizer is pulverized in advance to obtain crude particles include a sample mill and a jet mill.

[Crushing process]
The crude particles and the insulating carrier liquid are mixed, and the crude particles are milled while controlling the average temperature of (Tg-5) ° C. to Tg ° C. with respect to the glass transition temperature Tg ° C. of the crude particles. To obtain flat toner particles.

-Carrier liquid-
The carrier liquid is an insulating liquid for dispersing the toner particles. For example, a silicone solvent such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclotetrasiloxane, Exxon Isopar H, Isopar Paraffinic solvents such as M, Isopar L (trade name), Moresco White P-40, P-60, P-70 (trade name) manufactured by Matsumura Oil Co., Ltd., soybean oil, linseed oil, corn oil, sunflower Oil, palm oil, olive oil, vegetable oil such as jojoba oil, mineral oil such as gasoline, etc. are used.
A carrier liquid may be used individually by 1 type among the said components, and may mix and use 2 or more types. When the carrier liquid is used as a mixed system of two or more kinds, for example, a mixed system of paraffinic solvent and vegetable oil or a mixed system of silicone solvent and vegetable oil is exemplified.

When the carrier liquid is used alone, it is desirable to use a paraffinic solvent.
When the carrier liquid is used in a mixture of two or more, it is preferably a mixed system of paraffinic solvent and vegetable oil.

Carrier liquids are various auxiliary materials such as dispersants, dispersion stabilizers, emulsifiers, surfactants, stabilizers, wetting agents, thickeners, foaming agents, antifoaming agents, coagulants, gelling agents, sedimentation. It may contain an inhibitor, a charge control agent, an antistatic agent, an anti-aging agent, a softener, a plasticizer, a filler, a flavoring agent, an anti-tacking agent, a release agent, and the like.
Examples of the dispersion stabilizer include Solsperse 13940 (manufactured by Lubrizol Co., Ltd.) and Luminous (manufactured by Maruo Calcium Co., Ltd., calcium carbonate).

The crude particles are pulverized by a grinding force in an insulating carrier liquid while controlling the average temperature of (Tg-5) ° C. to Tg ° C. with respect to the glass transition temperature Tg ° C. of the coarse particles to have a flat shape Toner particles are prepared.
The glass transition temperature Tg of the crude particles is a value obtained by measurement according to JIS 7121-1987 using a differential scanning calorimeter [manufactured by Mac Science: DSC3110, thermal analysis system 001]. The melting point of a mixture of indium and zinc is used for temperature correction of the detection unit of the apparatus, and the heat of fusion of indium is used for correction of heat quantity. The sample is put in an aluminum pan, and an aluminum pan containing the sample and an empty aluminum pan for control are set and measured at a heating rate of 10 ° C./min. The temperature at the intersection of the extension line of the base line and the rising line in the endothermic part of the DSC curve obtained by measurement is defined as the glass transition temperature.

  In this embodiment, there are few restrictions on the type (viscosity) of the carrier liquid and the solid content concentration, and a high viscosity carrier liquid may be used. Even if the solid content concentration, that is, the concentration of crude particles is high, a flat toner is used. Particles are obtained. The mixing ratio of the coarse particles and the carrier liquid may be determined according to the liquid developer to be produced. However, flat toner particles can be obtained even if the concentration of the coarse particles is high. From the viewpoint of simplifying the entire process by omitting the step of performing and the step of concentrating, the mixing ratio of the coarse particles and the carrier liquid (the mass of the coarse particles / the mass of the carrier liquid) is 10/90 or more and 40/60 or less. It is desirable that it is 15/85 or more and 35/65 or less.

The above-mentioned crude particles and carrier liquid are mixed, and the crude particles are mixed in the carrier liquid while controlling the average temperature of (Tg-5) ° C. to Tg ° C. with respect to the glass transition temperature Tg (° C.) of the crude particles. Grind by grinding force.
The pulverizing apparatus is not particularly limited as long as it can pulverize the coarse particles in the carrier liquid with a grinding force to obtain flat toner particles, and examples thereof include a ball mill, a bead mill, a sand mill, an attritor, and a roll mill. Can be mentioned. From the viewpoint of efficiently obtaining flat toner particles by pulverizing the coarse particles, a ball mill, bead mill, or attritor media type pulverizer is desirable. As a commercially available grinding | pulverization apparatus used by this embodiment, Ashizawa Finetech Co., Ltd. Star mill DMS-L65 / LMZ015 is mentioned, for example.

  When the crude particles are pulverized by setting the average temperature in the pulverization process to less than (Tg-5) ° C., the particles obtained by pulverization do not have a flat shape, but spherical particles having a relatively large particle size or a large variation in particle size. It becomes particles. On the other hand, if the average temperature in the pulverization process exceeds Tg, the two layers are separated and agglomerated, and the pulverization does not proceed well, so that flat toner particles cannot be obtained. In this embodiment, by controlling the average temperature in the pulverization step to (Tg-5) ° C. or more and Tg ° C. or less, the solid content concentration in the mixture of the crude particles and the carrier liquid, that is, the content of the crude particles is high. However, the precursor is pulverized to obtain flat toner particles. From the above viewpoint, the average temperature in the pulverization step is preferably (Tg-3) ° C. or higher and (Tg-1) ° C. or lower.

  The temperature control in the pulverization step is measured, for example, by providing a temperature measurement means in a pulverization container (mill) and providing a temperature control means in the surroundings while measuring the temperature of the mixture of the coarse particles and the carrier liquid. Temperature control (heating or cooling) may be performed by temperature control means so that the target average temperature is obtained while observing the measured temperature. During the pulverization step, the temperature of the mixture varies somewhat, and even if it is less than (Tg-5) ° C or exceeds Tg ° C, the average temperature is (Tg-5) ° C or more and Tg ° C or less. Control may be performed so that However, when the time of less than (Tg-5) ° C. is increased, spherical particles are likely to be generated, and when the time of exceeding Tg ° C. is increased, the two layers are easily separated and aggregated. 5) It is desirable to control at a temperature not lower than C and not higher than Tg C.

  Through the above steps, for example, a liquid developer in which toner particles having a flat shape (flame shape) having a diameter of 2 μm or more and 5 μm or less and a thickness of 0.5 μm or more and 1 μm or less is dispersed in a carrier liquid is obtained. Note that after the pulverization step, dust and coarse particles may be removed by filtration using, for example, a membrane filter having a pore size of 100 μm. Moreover, you may add a carrier liquid as needed after a grinding | pulverization process.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention. In the text, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified.

[Example 1]
To 60 parts by mass of a polyester resin (trade name: FS-1 (Mw 14000) manufactured by Kao Corporation), cyan pigment C.I. I. Pigment Blue 15: 3 (manufactured by Clariant Co., Ltd.) (40 parts by mass) was added and kneaded with a pressure kneader to prepare a cyan pigment master batch.
Next, 25 parts by mass of the cyan pigment master batch obtained above, 70 parts by mass of polyester resin (trade name: FS-1 manufactured by Kao Corporation), and polyester polyol (DIC Corporation product) as a solid plasticizer ) Was mixed with a pressure kneader at 10 parts by mass.
The kneaded product was pulverized by a sample mill to produce coarse particles (crude particles) of cyan toner. The coarse particles produced at this time had a Tg of 40 ° C. and an average particle size of 18 μm.

40 parts by mass of the above-mentioned cyan toner crude particles, 60 parts by mass of white oil (Moleco White P-70 manufactured by Matsumura Oil Co., Ltd.) and 1 part by mass of a dispersion stabilizer (manufactured by Lubrizol Co., Ltd., Solsperse 13940) Each was added and the mixture was pulverized with a ball mill for 72 hours while controlling the average temperature of the mixture at 38 ° C. to obtain a toner particle dispersion (liquid developer).
When the obtained toner particles were observed with a scanning electron microscope, flat toner particles having a diameter of 2 μm to 5 μm and a thickness of 0.5 μm to 1 μm as shown in FIG. 1 were observed.

[Comparative Example 1]
A toner particle dispersion was obtained in the same manner as in Example 1 except that the average temperature in the pulverization step was changed to 30 ° C. in Example 1.
When the obtained toner particles were observed with a microscope, spherical toner particles having a particle diameter of about 5 μm were observed.

[Comparative Example 2]
In Example 1, except that the average temperature in the pulverization step was changed to 45 ° C., pulverization was performed in the same manner as in Example 1. However, the two layers separated and aggregated, and the pulverization was not successful.

[Example 2]
Toner having an average particle diameter of 20 μm was added to 85 parts by mass of white oil (Moleco White P-70, manufactured by Matsumura Oil Co., Ltd.) and 15 parts by mass of the crude cyan toner particles obtained in Example 1, and pulverized with a ball mill for 24 hours. A particle dispersion was obtained.
After 0.5 parts by mass of Solsperse 13940 was added to this dispersion, it was placed in a bead mill (Star Mill DMS-L65 / LMZ015 manufactured by Ashizawa Finetech Co., Ltd.) filled with 485 g of zirconia spheres (diameter 0.5 mm). While controlling the average temperature at 38 ° C., pulverization was performed for 2 hours at a flow rate of 150 ml / min / rotation speed of 2000 rpm.
When the shape of the toner particles obtained above was observed with a scanning electron microscope, it was a flat shape having a diameter of 10 μm to 20 μm and a thickness of 0.5 μm to 1 μm.

[Example 3]
<Production of developer>
For the formulation of Example 1, 1,4-cyclohexanedimethanol dibezoate (manufactured by CBC, benzoflex 352, melting point 118 ° C.) was used as a solid plasticizer instead of polyester polyol. The kneaded product was pulverized with a sample mill to produce coarse particles of cyan toner. The coarse particles produced at this time had a Tg of 35 ° C. and an average particle size of 20 μm.

60 parts by weight of white oil (Moleco White P-70 manufactured by Matsumura Oil Co., Ltd.) and 1 part by weight of Solsperse 13940 are added to 40 parts by weight of the above-mentioned cyan toner crude particles, and the average temperature of this mixture is controlled at 33 ° C. While being pulverized with a ball mill for 72 hours, a toner particle dispersion was obtained.
The obtained toner particles were observed with a scanning electron microscope. As a result, a flat toner having a diameter of 2 μm to 5 μm and a thickness of 0.5 μm to 1 μm, and a spherical toner particle having a major axis and a minor axis of 2 μm to 5 μm. Were mixed.

[Comparative Example 3]
A toner particle dispersion was obtained in the same manner as in Example 3 except that the average temperature in the pulverization step was changed to 25 ° C. in Example 3.
When the obtained toner particles were observed with a microscope, spherical toner particles having a particle diameter of about 5 μm were observed.

[Comparative Example 4]
The pulverization was performed in the same manner as in Example 3 except that the average temperature in the pulverization step was changed to 40 ° C. in Example 3. However, the pulverization was not successful because the two layers separated and aggregated.

[Comparative Example 5]
In the crude toner production process in Example 1, crude particles were produced without using polyester polyol (DIC Co., Ltd. product). The produced crude particles had a Tg of 50 ° C. and an average particle size of 19 μm.
60 parts by weight of white oil (Morethco White P-70 manufactured by Matsumura Oil Co., Ltd.) and 1 part by weight of Solsperse 13940 are added to 40 parts by weight of the crude cyan toner particles, and the average temperature of this mixture is controlled at 35 ° C. While being pulverized with a ball mill for 72 hours, a toner particle dispersion was obtained.
When the obtained toner particles were observed with a scanning electron microscope, they were spherical toner particles having a diameter of 3 μm or more and 7 μm or less.

[Comparative Example 6]
In the pulverization step in Comparative Example 5, pulverization was performed in the same manner as in Comparative Example 5 except that the average temperature was changed to 55 ° C.

[Example 4]
In a pressure kneader, 25 parts by mass of the master batch prepared in Example 1 was 70 parts by mass of polyester resin (FS-2 (Mw28000) manufactured by Kao Corporation) and 10 parts by mass of polyester polyol (DIC product). Kneaded. The kneaded product was pulverized with a sample mill to produce coarse particles of cyan toner. The Tg of the coarse particles produced at this time was 37 ° C. 60 parts by mass of Moresco White P-70 and 1 part by mass of Solsperse 13490 are added to 40 parts by mass of the cyan toner crude particles, and the toner particles are pulverized with a ball mill for 72 hours while controlling the average temperature of the mixture at 35 ° C. A dispersion was obtained. The toner particles obtained at this time were flat with a diameter of 2 μm to 6 μm and a thickness of 0.5 μm to 1 μm.

[Example 5]
Moreover, FS-2 of Example 4 was changed into FS-3 (Mw8200), and the crude particle was produced, without changing another structure. The Tg of the coarse particles produced at this time was 38 ° C. 60 parts by mass of Moresco White P-70 and 1 part by mass of Solsperse 13490 are added to 40 parts by mass of the cyan toner crude particles, and the toner particles are pulverized with a ball mill for 72 hours while controlling the average temperature of the mixture at 36 ° C. A dispersion was obtained. The toner particles obtained at this time were flat with a diameter of 2 μm to 5 μm and a thickness of 0.5 μm to 1 μm.

[Example 6]
The white oil of Example 1 was changed from Moresco White P-70 to P-40, and the toner was pulverized with a ball mill for 72 hours while controlling the average temperature of this mixture at 35 ° C. without changing the other components. A particle dispersion was obtained. The toner particles obtained at this time were flat with a diameter of 1 μm to 5 μm and a thickness of 0.5 μm to 1 μm.

Claims (5)

A crude particle preparing step of preparing crude particles containing a binder resin containing polyester and a solid plasticizer;
The crude particles and the insulating carrier liquid are mixed, and the crude particles are milled while controlling the average temperature of (Tg-5) ° C. to Tg ° C. with respect to the glass transition temperature Tg ° C. of the crude particles. Crushing step to obtain flat toner particles by crushing with,
A method for producing a liquid developer comprising:   The method for producing a liquid developer according to claim 1, wherein the solid plasticizer is a polyester polyol.   3. The liquid development according to claim 1, wherein in the pulverization step, a mixing ratio of the coarse particles and the carrier liquid (a mass of the coarse particles / a mass of the carrier liquid) is set to 10/90 or more and 40/60 or less. Manufacturing method.   The method for producing a liquid developer according to any one of claims 1 to 3, wherein a ball mill, a bead mill, or an attritor is used as a pulverizer for pulverizing the crude particles in the pulverization step. The coarse particle preparation step includes:
Kneading the binder resin containing the polyester and the solid plasticizer to obtain a kneaded product;
Crushing the kneaded product to obtain the crude particles;
The method for producing a liquid developer according to any one of claims 1 to 4, further comprising: