JP2018022069A - Manufacturing method for liquid developer and manufacturing apparatus for liquid developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a liquid developer having small particle size and good dot reproducibility in good yield.SOLUTION: There is provided a manufacturing method for a liquid developer comprising processes of: preparing a first fluid dispersion having pigment dispersed by mixing the pigment, a first solvent, and a binder resin; obtaining a second fluid dispersion by adding a second solvent to the first fluid dispersion and precipitating particles of the binder resin containing the pigment; and obtaining a third fluid dispersion by distilling the first solvent from the second fluid dispersion. The second solvent is electrically insulative. The process of obtaining the second fluid dispersion includes: a first stirring process of performing shear stirring of the first fluid dispersion in a first speed range; and a second stirring process of performing shear stirring in a second speed range. An average speed in the first speed range is faster than an average speed in the second speed range. In the process of obtaining the second fluid dispersion, the first stirring process is shifted to the second stirring process when viscosity of the first fluid dispersion enters a specific range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a liquid developer and an apparatus for manufacturing a liquid developer used in an image forming apparatus using an electrophotographic system.

In recent years, for image forming apparatuses such as copying machines, facsimiles, and printers that use an electrophotographic system, it has been desired to improve the quality of color images and speed up the apparatus. Among them, high-resolution high-speed digital printing using a liquid developer that excels in high-resolution dot and fine-line image reproducibility, gradation reproducibility, and color reproducibility, and is excellent in high-speed image formation. Development of equipment is becoming popular.
Conventionally, a liquid developer in which toner particles, which are colored resin fine particles, are dispersed in a carrier liquid is known. As the carrier liquid, an electrically insulating liquid such as a hydrocarbon-based organic solvent or silicone oil is generally used because it does not disturb the potential of the electrostatic latent image on the photosensitive drum.
As a method for producing a liquid developer, there is a method in which a dry toner is produced by a dry pulverization method, a suspension polymerization method, an emulsion polymerization method or the like and then dispersed in a carrier liquid as described above. In addition, methods such as a wet pulverization method and a precipitation method (coacervation method) are also known.

Among these, the precipitation method is expected to be a method for producing a liquid developer in which spherical toner particles are dispersed in a carrier liquid at a relatively low cost, and development is in progress. (For example, patent document 1).
In the case of producing a liquid developer by the precipitation method, the process includes (1) a step of mixing a colorant, a binder resin, a solvent that dissolves the binder resin, and a solvent that does not dissolve the binder resin. Generally, it is classified into at least two steps of distilling off the solvent that dissolves the binder resin.
Patent Document 2 proposes a method of depositing a binder resin on the surface of a pigment which is a colorant in the step (2) by adding a specific dispersant. At this time, it is described that a liquid developer in which toner particles having a particle diameter of 1.4 μm to 1.6 μm are dispersed can be manufactured by stirring with a high-speed shearing stirring device.

JP 7-319221 A Japanese Patent No. 4022078

In the step (2) in the above-described precipitation method, that is, the step of distilling off the solvent for dissolving the binder resin, it is common to use a decantation method or an evaporation method. However, the decantation method takes a lot of time, and there are many restrictions on the selection of a solvent that dissolves the binder resin and a solvent that does not dissolve the binder resin, and is not suitable for production.
When the evaporation method is used, the solvent that dissolves the binder resin is volatilized and distilled while the inside of the container is evacuated, but high shear stirring is performed during the process corresponding to (2) as in Patent Document 2. Bumping and intense foaming occur. When bumping or bubbling occurs during evacuation, liquid flows into the evacuation path, resulting in problems such as a decrease in evacuation speed or stop of the process.

In order to avoid this problem, if the evacuation rate is remarkably slowed or the processing pressure is set high, a long time is required for the production, for example, it takes a long time to distill off. In addition, when the process is terminated without sufficiently distilling off the solvent that dissolves the binder resin, the toner particles gradually dissolve, soften, and swell, which adversely affects the storage stability of the liquid developer. there is a possibility.
An object of the present invention is to provide a manufacturing method and a manufacturing apparatus capable of manufacturing a liquid developer excellent in dot reproducibility with good yield, including toner particles having a small particle size and few coarse particles.

The above object is achieved by the present invention described below.
The present invention includes (1) a step of preparing a first dispersion in which the pigment is dispersed by mixing a pigment, a first solvent, and a binder resin soluble in the first solvent. ,
(2) A second solvent, which is a poor solvent for the binder resin, is added to the first dispersion liquid to precipitate particles of the binder resin containing the pigment, and the second particles are dispersed. And (3) a third dispersion in which the first solvent is distilled off from the second dispersion, and the particles are dispersed in a liquid containing the second solvent. A method of producing a liquid developer, comprising the step of obtaining a liquid,
The second solvent is electrically insulating;
The step of obtaining the second dispersion includes a first stirring step of shearing and stirring the first dispersion at a first speed range, and a shearing of the dispersion after the first stirring step at a second speed range. A second stirring step of stirring,
The average value of the shear rate in the first speed range is faster than the average value of the shear rate in the second speed range,
In the step of obtaining the second dispersion, when the viscosity of the first dispersion becomes 1/50 or more and 1/5 or less of the viscosity at the start of the step of obtaining the second dispersion. The present invention relates to a method for producing a liquid developer, characterized in that a transition is made from the stirring step to the second stirring step.
Further, the present invention is an apparatus for producing a liquid developer comprising at least particles containing a pigment and a binder resin, and an insulating liquid which is a poor solvent for the binder resin,
A means for adding and mixing the insulating liquid while stirring the dispersion containing the pigment and binder resin, and a means for monitoring the viscosity of the dispersion during stirring.
The present invention relates to an apparatus for producing a liquid developer, which has a mechanism for changing a stirring speed in accordance with a change in a monitored value of viscosity.

  According to the present invention, it is possible to produce a liquid developer containing toner particles having a small particle size and few coarse particles and having excellent dot reproducibility with high yield.

Example of liquid developer manufacturing equipment Example of liquid developer manufacturing equipment Example of image forming apparatus applicable to liquid developer

In the present invention, the description of “XX or more and XX or less” or “XX to XX” representing a numerical range means a numerical range including a lower limit and an upper limit as endpoints unless otherwise specified.
Below, the manufacturing method of the liquid developer of this invention is demonstrated.
[Step of preparing first dispersion]
In the step of preparing the first dispersion, the pigment is dispersed by mixing the pigment, the first solvent, and a binder resin that is soluble in the first solvent. The pigment, the first solvent, and the binder resin may be directly mixed to form the first dispersion, but the pigment may be preliminarily dispersed and applied as necessary.

For the step of preparing the first dispersion in which the pigment is dispersed and the preliminary dispersion of the pigment, for example, ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill A dispersing device such as an ultrasonic homogenizer, a pearl mill, or a wet jet mill can be used.
In order to improve the pigment dispersibility, a pigment dispersant as described below may be added.
In the case of predispersing the pigment, the pigment, the pigment dispersant, and the first solvent are mixed using the above-described apparatus, and at least the mixed solution and the binder resin or the solution of the binder resin in the first solvent are mixed. Thus, a first dispersion can be obtained. After obtaining the first dispersion, it is preferable to perform stirring to such an extent that the dispersion state of the pigment can be maintained until a step of obtaining a second dispersion described later.

[Step of obtaining second dispersion] (first stirring step, second stirring step)
In this step, the second solvent is added to the first dispersion. As the second solvent, it is necessary to use a so-called poor solvent that does not dissolve the binder resin. When the solubility of the binder resin is lowered by the addition of the poor solvent, the binder resin particles containing the pigment are precipitated. The pigment is preferably included in a binder resin.

Various materials that can be used for manufacturing the liquid developer will be described later.
As a result of the study by the present inventors, the toner is obtained by applying a high shear rate stirring share after the start of the addition of the poor solvent in this step or the start of the precipitation of the particles until the particle precipitation is almost finished. It was found that the particle size can be reduced. This is thought to be because the precipitation of the binder resin is still unstable at the initial stage of phase separation due to the addition of a poor solvent, so that it is possible to achieve finer particles by providing a high stirring share. It is done.

As a method of giving a high agitation share, there can be mentioned a method using ultrasonic waves and a method giving a lower frequency vibration, but mechanical shear agitation is used as a method that is easier to use for production and has a wider control range. A shearing stirrer can be suitably used.
As the shear stirring device, for example, a homogenizer or a homomixer can be used. Specifically, Talux (manufactured by IKA Japan Co., Ltd.), homomixer (manufactured by Primix Co., Ltd.), Claremix (manufactured by M Technique Co., Ltd.) and the like can be suitably used.

The shear share ability of these shear stirrers can be compared by the shear rate (1 / s). For example, each of the various shear stirring devices described above has a configuration in which a rotor that rotates with a clearance is provided inside a fixed stator. In this case, the shear rate (1 / s) is calculated by the following formula.
Shear speed (1 / s) = rotor peripheral speed (mm / s) / rotor-stator clearance (mm)

In order to obtain a liquid developer in which small-diameter toner particles that achieve excellent dot reproducibility, which is the object of the present invention, are obtained, the above-described initial stage of phase separation in this step (first stirring step described later) However, although it depends on the shape of the shear stirring device, specifically, the average value of the shear rate (the average value of the shear rate in the following first speed range) is preferably 15000 (1 / s) or more. 25000 (1 / s) or more is more preferable. On the other hand, the upper limit is not particularly limited, but is preferably 150,000 (1 / s) or less, more preferably 100,000 (1 / s) or less.
Although depending on the selection of the binder resin to be used, the first solvent, and the second solvent, the particle size can be reduced when the shear rate is 15000 (1 / s) or more.

However, if the stirring share at a high shear rate as described above is continued after the toner particles are almost completely precipitated in this step, coarse particles are generated or the yield of the liquid developer is deteriorated. Problem has occurred.
This is because the viscosity of the dispersion liquid is high before the particles are precipitated, and the viscosity of the dispersion liquid is decreased at the stage where the precipitation of the particles is almost completed. When a low-viscosity dispersion liquid is stirred at a high shear rate, the liquid flow of the dispersion liquid becomes violent and the dispersion liquid splatters outside the reaction vessel, causing a reduction in yield. Further, when the dispersion liquid stays in a portion outside the stirring region in the apparatus, the precipitated particles reaggregate to generate coarse particles. Further, bubbles are generated by strong stirring, and the stirring force is difficult to be transmitted in the vicinity of the bubbles, which also causes coarse particles due to reaggregation of the precipitated particles.

In order to avoid this problem, the present invention defines the first stirring step from the start of the addition of the poor solvent in this step or from the start of the precipitation of the particles to the stage where the precipitation of the particles is almost finished. Thus, a method of giving a high agitation share only during this process has been reached. And after particle | grain precipitation is almost complete | finished, it is set as a 2nd stirring process, and a dispersion liquid is stirred with a lower stirring share. That is, the step of obtaining the second dispersion includes a first stirring step in which the first dispersion is shear-stirred in a first speed range, and the dispersion after the first stirring step in a second speed range. A second stirring step of shearing stirring. The average value of the shear rate in the first speed range is faster than the average value of the shear rate in the second speed range.
Specifically, in the second stirring step, it is preferable to perform stirring at an average shear rate of 0 (1 / s) to 14000 (1 / s). More preferably, it is 0 (1 / s) or more and 10000 (1 / s) or less.
By using such a method, a liquid developer having excellent dot reproducibility can be produced.
The first stirring step may be started when the second solvent is added to the first dispersion, or may be started prior to the addition of the second solvent to the first dispersion. Good.

The transition from the first stirring step to the second stirring step can be determined by checking the viscosity change of the dispersion.
Specifically, the dispersion is in a range of 1/50 to 1/5 (preferably 1/50 to 1/10) of the dispersion viscosity (initial viscosity) at the start of the step of obtaining the second dispersion. When the viscosity decreases, the process proceeds to the second stirring step. About the value of the viscosity which transfers to a 2nd stirring process, it can change with materials to be used and those mixing ratios. Therefore, it is preferable to set a more suitable value by sampling the dispersion liquid in the middle of the process and observing the degree of precipitation of particles.
The transition from the first stirring process to the second stirring process is not necessarily performed rapidly, and the speed may be changed gradually or the speed may be changed stepwise. The viscosity of the dispersion at the start of the step of obtaining the second dispersion is preferably 20 mPa · s or more and 300 mPa · s or less.

In this step and the step of obtaining the third dispersion, which is the next step, apart from the device that gives a high stirring share represented by a shear stirring device, in order to avoid reaggregation of the precipitated particles, the entire dispersion is homogeneous. It is desirable to have an agitation means for converting to
Specific examples of the stirring means include a method using a magnetic stirrer and a rotating magnetic stirrer, and a method using a stirring blade and a stirring blade.
The temperature of the dispersion liquid in this step is preferably controlled to be not lower than the freezing point and not higher than the boiling point of the first solvent and the second solvent, and not higher than the glass transition point of the binder resin. Specifically, a range of 0 ° C. or more and 60 ° C. or less is preferable.

[Step of obtaining third dispersion]
Following the step of obtaining the second dispersion, a step for distilling off the first solvent from the dispersion is performed. The step of obtaining the third dispersion is a step of distilling the first solvent from the second dispersion to disperse the pigment-containing binder resin particles in the liquid containing the second solvent. As a method for distilling off the first solvent, an evaporation method using a vacuum facility can be suitably used.
A general rotary evaporator can be used for the evaporation method. Further, as shown in an example of a liquid developer manufacturing apparatus described later, a process for continuously distilling off the first solvent from the process of obtaining the second dispersion using one apparatus is performed. You can also.
In this process, in order to avoid reaggregation of the precipitated particles and to homogenize the entire dispersion, the container itself has a mechanism that rotates or swings, or a magnetic stirrer, stirring blade, stirring blade, etc. It is preferable to use and stir.

In this step, the first solvent is distilled off by gradually or stepwise reducing the pressure in the container from atmospheric pressure to preferably 1000 Pa, more preferably to 100 Pa.
The temperature of the dispersion liquid in this step is preferably controlled to be not lower than the freezing point and not higher than the boiling point of the first solvent and the second solvent, and not higher than the glass transition point of the binder resin. Specifically, a range of 0 ° C. or more and 60 ° C. or less is preferable. In order to efficiently distill off the first solvent, it is more preferably in the range of 40 ° C. or more and 60 ° C. or less.

[Liquid developer preparation process]
It is also possible to use the third dispersion as it is as a liquid developer. However, as a liquid developer preparation step, another liquid is added to the third dispersion or the second contained in the third dispersion for the purpose of improving the function of the liquid developer or for other purposes. It is also possible to replace other solvents with other liquids.
In this step, various dispersants, charge control agents, and other various additives can be added. Furthermore, unit operations such as cleaning of toner particles can be appropriately added in this step.

Various materials that can be used for manufacturing the liquid developer will be described.
Examples of the binder resin include the following. Styrene such as polyester, modified polyester, polystyrene, poly-p-chlorostyrene, polyvinyltoluene and the like, and substituted polymers thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene copolymers such as styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-acrylonitrile copolymer; polyvinyl chloride, phenol resin, natural modified phenol resin, natural resin modified maleic acid resin , Le resins, methacrylic resins, polyvinyl acetate, silicone resin, polyurethane, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone - indene resins, and petroleum resins.
The amount of the binder resin used is preferably 20 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the first solvent.

  Further, the liquid developer may contain a wax component for improving the fixability.

The pigment as the colorant used in the liquid developer is not particularly limited, and all commercially available organic pigments and inorganic pigments, or pigments dispersed in an insoluble resin or the like as a dispersion medium, the pigment surface A resin grafted resin can be used.
Specific examples of the organic pigment and the inorganic pigment include, for example, the following ones exhibiting a yellow color. C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; I. Bat yellow 1, 3, 20

Examples of those exhibiting red or magenta color include the following. C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269; I. Pigment violet 19; C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35.
Examples of the pigment exhibiting blue or cyan include the following. C. I. Pigment blue 2, 3, 15: 2, 15: 3, 15: 4, 16, 17; I. Bat Blue 6; C.I. I. Acid Blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton.

  Examples of the green pigment include the following. C. I. Pigment Green 7, 8, 36. Examples of the orange pigment include the following. C. I. Pigment Orange 66, 51. Examples of black pigments include the following. Carbon black, titanium black, aniline black. Specific examples of the white pigment include the following. Basic lead carbonate, zinc oxide, titanium oxide, strontium titanate.

Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments may be used as required.
The amount of the pigment used is preferably 10 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the binder resin.

A pigment dispersant may be added when dispersing the pigment. Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a polyester and a modified product thereof. , Modified polyacrylates, aliphatic polycarboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, pigment derivatives, and the like.
The amount of the pigment dispersant used is preferably 5 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the pigment.

In order to stably disperse the toner particles, it is preferable to add a toner dispersant. Examples of the toner dispersant include commercially available Ajisper PB817 (manufactured by Ajinomoto Co.), Solsperse 11200, 13940, 17000, 18000 (manufactured by Nippon Lubrizol Co., Ltd.) and the like.
The amount of the toner dispersant used is preferably 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin.

The first solvent is not particularly limited as long as it dissolves the binder resin. For example, ethers such as tetrahydrofuran, ketones such as methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate, and halides such as chloroform. Can be mentioned. Furthermore, aromatic hydrocarbons such as toluene and benzene may be used when the resin has a dissolving ability.
The determination of whether or not to “dissolve the binder resin” (whether or not it is a poor solvent) is, for example, when the resin to be dissolved is 1 part by mass or less with respect to 100 parts by mass (25 ° C.) of solvent "No" (determined as a poor solvent).

The second solvent is electrically insulating (insulating liquid), and it is necessary that the above-described binder resin is not dissolved (poor solvent). Electrically insulating preferably has a volume resistivity of 1 × 10 ⁹ to 1 × 10 ¹³ Ωcm. The said 2nd solvent can be used as a carrier liquid which comprises a liquid developer as it is. If necessary, another insulating liquid may be added to form a carrier liquid, or the toner particles and the second solvent may be separated and replaced with another insulating liquid.
As an insulating liquid that can be added to or substituted for the second solvent and the second solvent, a hydrocarbon-based organic solvent such as an isoparaffin-based solvent or silicone oil can be suitably used. However, in order to further improve the dot reproducibility of the toner particles, a curable solvent may be used without imparting fixing properties to the toner particles.
The amount of the second solvent added in the step of obtaining the second dispersion is preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the binder resin.

The curable solvent can be selected from polymerizable liquid monomers. Examples of the polymerizable liquid monomer include acrylic monomers, vinyl ether compounds, and cyclic ether monomers such as epoxy and oxetane.
A vinyl ether compound is preferred as the second solvent or insulating liquid. The vinyl ether compound refers to a compound having a vinyl ether structure (—CH═CH—O—C—).
The vinyl ether structure is preferably represented by R—CH═CH—O—C— (R is hydrogen or alkyl having 1 to 3 carbon atoms, preferably hydrogen or methyl).
Among them, particularly preferred are dodecyl vinyl ether (DDVE) dipropylene glycol divinyl ether, dicyclopentadiene vinyl ether, cyclohexanedimethanol divinyl ether, tricyclodecane vinyl ether, trimethylolpropane trivinyl ether, 2-ethyl-1,3-hexane. Diol divinyl ether, 2,4-diethyl-1,5-pentanediol divinyl ether, 2-butyl-2-ethyl-1,3-propanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol tetravinyl ether, 2,2 -Bis (4-hydroxycyclohexyl) propane divinyl ether, 1,2-decanediol divinyl ether and the like.

The SP value of the binder resin, the first solvent, and the second solvent is preferably larger in the order of the binder resin, the first solvent, and the second solvent, and the difference between the SP values of the binder resin and the second solvent. Is preferably 2.5 or more. The SP value (solubility parameter: solubility parameter) is a factor that determines the solubility of the resin and the solvent. In general, polar resins tend to be soluble in polar solvents and difficult to dissolve in nonpolar solvents. On the other hand, non-polar resins tend to reverse. A factor for determining the strength of this affinity is the solubility parameter (SP value), which is indicated by δ. In general, the smaller the difference between the SP values of the solvent and the solute, the greater the solubility. The SP value is a value obtained by calculation from the evaporation energy and molar volume of atoms and atomic groups by Fedors described in coating basics and engineering (page 53, Yuji Harasaki, Processing Technology Study Group). The unit of the SP value is (cal / cm ³ ) ^1/2 , but 1 (cal / cm ³ ) ^1/2 = 2.046 × 10 ³ (J / m ³ ) ^1/2 (J / m ³ ) Can be converted to ^1/2 units.

In addition, when the carrier liquid is cured using light energy such as ultraviolet rays, it is preferable to add a photopolymerization initiator to the carrier liquid. A photopolymerization initiator is a compound for generating acid and radicals by sensing light of a predetermined wavelength. Examples of such a cationic photopolymerization initiator include, but are not limited to, onium salt compounds, sulfone compounds, sulfonic acid ester compounds, sulfonimide compounds, diazomethane compounds, and the like. Examples of the radical photopolymerization initiator include, but are not limited to, benzoin derivatives. Although the usage-amount of a photoinitiator is not specifically limited, It is preferable that it is 0.01-5 mass parts with respect to 100 mass parts of polymerizable liquid monomers.
In addition to the photopolymerization initiator, a sensitizer may be added as necessary for the purpose of, for example, improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength.

In addition, a polymerization inhibitor can be added so that the polymerization does not start before the curable carrier liquid receives predetermined light energy. Examples of the cationic polymerization inhibitor include alkali metal compounds, alkaline earth metal compounds, and amines.
Examples of radical polymerization inhibitors include phenolic hydroxyl group-containing compounds, quinones such as methoquinone (hydroquinone monomethyl ether), hydroquinone, 4-methoxy-1-naphthol, hindered amine antioxidants, 1,1-diphenyl-2. -Picrylhydrazyl free radicals, N-oxyl free radical compounds, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenol antioxidants, ascorbic acids, zinc sulfate, thiocyanates, thiourea Derivatives, various sugars, phosphate antioxidants, nitrites, sulfites, thiosulfates, hydroxylamine derivatives, aromatic amines, phenylenediamines, imines, sulfonamides, urea derivatives, oximes, dicyandiamide and poly Alkylene poly Polycondensates Min, sulfur-containing compounds such as phenothiazine, complexing agents based on tetraazacyclododecane Anne Ren, like hindered amines.
The addition amount of the polymerization inhibitor is preferably 1 to 5000 ppm on a mass basis with respect to the liquid developer.

The liquid developer may contain a charge control agent as necessary. A well-known thing can be utilized as a charge control agent. Specific compounds include
Oils and fats such as linseed oil and soybean oil; alkyd resins, halogen polymers, aromatic polycarboxylic acids, acidic group-containing water-soluble dyes, aromatic polyamine oxidation condensates, cobalt naphthenate, nickel naphthenate, iron naphthenate, naphthene Metal soaps such as zinc oxide, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate, aluminum stearate, cobalt 2-ethylhexanoate; petroleum metal sulfonates, Sulfonic acid metal salts such as metal salts of sulfosuccinic acid esters; Phospholipids such as lecithin; Salicylic acid metal salts such as t-butyl salicylic acid metal complexes; Polyvinylpyrrolidone resins, polyamide resins, sulfonic acid-containing resins, hydroxybenzoic acid derivatives, etc. It is done.
In addition, the colored resin dispersion may contain other additives as necessary.

(Liquid developer production equipment)
The present invention is an apparatus for producing a liquid developer comprising at least particles containing a pigment and a binder resin, and an insulating liquid which is a poor solvent for the binder resin,
A means for adding and mixing the insulating liquid while stirring the dispersion containing the pigment and binder resin, and a means for monitoring the viscosity of the dispersion during stirring.
The present invention relates to an apparatus for producing a liquid developer, which has a mechanism for changing a stirring speed in accordance with a change in a monitored value of viscosity.
Hereinafter, an example of the liquid developer production apparatus of the present invention will be described and described with reference to FIGS.
The reaction vessel 1 is made of glass, has an inner diameter of 150 mm, an inner height of 150 mm, and a volume of about 2.6 liters. The side of the container can be controlled with hot / cold water and a ribbon heater. The stainless steel container lid 2 has an O-ring arranged on the contact surface with the reaction container, and has a structure that can be evacuated. Each component introduced into the container can be similarly vacuum sealed.
A stirring blade 3 and a shear stirring device 4 are respectively introduced into the reaction vessel 1. A thermometer or a thermocouple (not shown) may be introduced into the reaction vessel 1.
A motor (not shown) (three-one motor manufactured by Shinto Kagaku Co., Ltd.) and a torque meter capable of displaying and outputting the rotational torque of the motor are connected to the shaft of the stirring blade 3.
The dispersion liquid containing the pigment and the binder resin is stirred by the stirring blade 3. The dispersion containing the pigment and the binder resin is preferably a dispersion containing the pigment, the first solvent described above, and a binder resin that is soluble in the first solvent.
Examples of means for adding and mixing the insulating liquid while stirring the dispersion include means for providing a liquid supply port (not shown) and adding the mixture using a known liquid feed pump.

  In the step of obtaining the third dispersion, the shear stirring device 4 is removed from the container lid 2 and the vacuum exhaust port 5 is introduced. Connected to the vacuum exhaust port 5 is a vacuum exhaust facility comprising at least a reflux condenser, a solvent trap ball, and a vacuum pump (not shown). The first solvent can be distilled off by the evacuation equipment. The vacuum evacuation equipment preferably has the ability to evacuate the reaction vessel 1 quickly to 1000 Pa, more preferably to 100 Pa. The reaction vessel 1 and each component preferably have a vacuum resistance of 100 Pa or less.

From the torque value of the motor connected to the stirring blade 3, the viscosity of the dispersion during stirring can be monitored as follows. A correlation table or correlation equation between the torque value and the viscosity of the dispersion is obtained in advance from the actually measured torque value when the stirring blade 3 is rotated at 100 rpm and the viscosity of the dispersion using a viscometer. Thereby, the motor torque value of the stirring blade 3 becomes a means for monitoring the viscosity of the dispersion during stirring. Furthermore, you may provide the control mechanism which can change the rotation speed of the shear stirring apparatus 4 automatically according to the monitor value of the dispersion viscosity computed from the torque value of a motor.
Further, the means for monitoring the viscosity of the dispersion is not limited to the method of measuring the motor torque of the stirring blade 3, but the method of directly introducing the measuring part of the viscometer into the reaction vessel 1, the load using a piezoelectric element or the like. A method of introducing a measuring device into the reaction vessel 1 can also be used.

As a mechanism for changing the stirring speed in accordance with the change in the monitor value of the viscosity, the viscosity of the dispersion during stirring is from 1/50 to 1/5 of the viscosity of the dispersion before adding the insulating liquid (preferably Includes a means for changing the stirring speed when the viscosity of the dispersion is lowered to a range of 1/50 to 1/10. Examples of the change in the stirring speed include a mode in which the shear rate (average speed) is changed from the first speed range to the second speed range.
When the liquid developer having the same specification is produced a plurality of times, it is not always necessary to have a means for monitoring the viscosity of the dispersion in the apparatus. In this case, the time during which the number of revolutions of the shearing stirring device 4 is changed by adding a second solvent or sampling the mixture in the middle of the process to measure the viscosity, or confirming the generation of particles using a microscope, etc. Determine the amount. At the time of producing a plurality of times, the number of rotations of the shear stirring device 4 may be changed at the stage determined by this method or when the second solvent has been added.

(Measurement methods and evaluation indices for various physical properties)
Below, the measuring method and evaluation index of various physical properties of the liquid developer and its raw materials used in this embodiment will be described.
<Measurement of weight average molecular weight of binder resin>
The binder resin was dissolved using tetrahydrofuran as a solvent, and HLC8120 GPC (
Using a detector: RI) (manufactured by Tosoh Corporation), the molecular weight analysis of the polyester resin constituting the toner particles was performed, and the weight average molecular weight was calculated.

<Yield of liquid developer>
The yield of the liquid developer was calculated from the following formula.
Developer weight obtained after the step of obtaining the third dispersion / Developer charge weight × 100
Evaluation index:
The yield of the liquid developer is A: 94% or more B: 90% or more and less than 94% C: 85% or more and less than 90% D: less than 85%

<Measurement of viscosity of liquid mixture in production of liquid developer>
Eight levels of standard solutions of 1 mPa · s to 1000 mPa · s were prepared in advance. This was put into the liquid developer production apparatus in this example and stirred. At this time, the stable value of the torque meter value of the motor attached to the shaft of the stirring blade 3 was measured. Separately, the viscosity of the standard solution was measured at a shear rate of 1000 (1 / s) using a viscometer (ARES-G2 manufactured by TA Instruments Japan Co., Ltd.).
The torque value and viscosity of the stirring blade 3 in each of the obtained standard solutions were plotted, and a calibration curve was created so that the viscosity of the mixed solution could be calculated from the torque value of the stirring blade.

<Measurement of Volume Average Particle Diameter (Mv) of Toner Particles Constructing Liquid Developer>
0.05 ml of liquid developer was diluted with 4 ml of dodecyl vinyl ether (DDVE) and stirred using a shaker. The volume average particle diameter (Mv) was measured using a particle size distribution analyzer Nanotrac-Wave EX150 manufactured by Microtrack Bell Co., Ltd.

<Evaluation of the amount of coarse particles in the liquid developer>
0.02 ml of liquid developer was placed on a transparent slide glass, a cover glass was placed, and observed with a digital microscope VHX-200 manufactured by Keyence Corporation at a magnification of 1000, and evaluated according to the following indices.
Evaluation index:
The number of particles of 5 μm or more in one field of view of 1000 times is A: 0 B: 1 to 2 C: 3 or more

<Evaluation of dot reproduction>
In the dot reproducibility evaluation, a fixed image of 600 dpi 1 dot 1 space was observed with a digital microscope VHX-200 (manufactured by Keyence Corporation) 1000 times, and evaluation was performed using the following indices.
Evaluation index:
A: The dots are uniform and have no chipping.
B: The dots are independent and there are no harmful effects such as scattering.
C: A dot can be recognized.
D: Many portions where dots cannot be recognized are observed.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples. “Parts” and “%” are based on mass unless otherwise specified.
(Manufacture of liquid developer 1)
<Process of adjusting the first dispersion>
An isocyanate group is charged with 100 parts by mass of a toluene solution (solid content 50%) of a polycarbodiimide compound having a carbodiimide equivalent of 262 having an isocyanate group and 8.5 parts by mass of N-methyldiethanolamine and maintained at about 100 ° C. for 3 hours. And a hydroxyl group were reacted.
Next, 39.6 parts of an ε-caprolactone self-polycondensate having a carboxyl group at the terminal and having a number average molecular weight of 8500 was charged and held at about 80 ° C. for 2 hours to react the carbodiimide group and the carboxyl group, and then under reduced pressure. The toluene was distilled off to obtain a pigment dispersant (solid content 100%) having a number average molecular weight of about 13,000.
Pigment C.I. I. Pigment Blue 2; manufactured by Dainichi Seika Kogyo Co., Ltd .: 10 parts by mass. Pigment dispersant: 10 parts by mass. Tetrahydrofuran (first solvent): 130 parts by mass. Mix glass beads having a diameter of 0.5 mm. The pigment dispersion 1 was obtained by stirring and mixing with a bead mill.
-Pigment dispersion 1: 100 parts by mass-Polyester resin 1 solution (a copolymer comprising 50 parts by weight of terephthalic acid and 10 parts by weight of trimellitic acid as acid units, and 60 parts by weight of bisphenol A as alcohol units, Binder resin soluble in the above solvent, weight average molecular weight 15000) and tetrahydrofuran premixed in a mass ratio of 1: 1): 120 parts by mass Azisper PB-817; Ajinomoto Fine Techno Co., Ltd .: 5 mass Part The above was introduced into the liquid developer production apparatus shown in FIG. 1, and the stirring blade 3 was rotated at 100 rpm and mixed to obtain a first dispersion.

<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 98.0 mPa · s (motor torque value 0.111 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From a liquid supply port (not shown in FIG. 1), 190 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for polyester resin 1, is added at a constant drop rate of 10.3 ml / min. The shear stirring device 4 was rotated at 24000 rpm (shear speed 45220 (1 / s)) at the same time as the dropping was started. (First stirring step)
26 minutes after the start of dropping, the first dispersion viscosity became 2.5 mPa · s (1/40 of initial viscosity, motor torque value 0.021 N · m), and at the same time, the rotational speed of the shear stirring device 4 was 5000 rpm. (Shear rate 9420 (1 / s)). (Second stirring step)
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.

<Step of obtaining third dispersion>
The shear stirrer 4 and the liquid supply port were removed from the container lid 2, the vacuum exhaust port 5 shown in FIG. 2 was attached, and vacuum exhaust was started while the stirring blade 3 continued to rotate (100 rpm). At this time, the temperature was adjusted so that the temperature of the dispersion was 50 ° C. After 40 minutes from the start of evacuation, the inside of the reaction vessel became 500 Pa, and the evacuation was continued as it was and the atmosphere was released 60 minutes after the start of evacuation to obtain a third dispersion. The yield of the third dispersion with respect to the charged amount was 95% and was sufficiently high.

<Liquid developer preparation process>
100 parts by mass of the obtained third dispersion liquid, 0.10 parts by mass of resinol S-10 (hydrogenated lecithin, manufactured by Nikko Chemicals Co., Ltd.), a poor solvent for polyester resin 1, and insulating dipropylene glycol di 90 parts by mass of vinyl ether, 0.30 parts by mass of a photopolymerization initiator represented by the following formula (A-1), 1 part by mass of KAYAKUURE-DETX-S (manufactured by Nippon Kayaku Co., Ltd.) are added, and a liquid developer 1 was obtained.

The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 1 was measured. As a result, the volume average particle size (Mv) was 0.84 μm.
The evaluation result of the amount of coarse particles of the liquid developer 1 was a liquid developer in which there were no coarse particles having a particle size of 5 μm or more in one field of view and toner particles having a uniform particle size were dispersed. (Evaluation A)

(Manufacture of liquid developer 2)
<Process of adjusting the first dispersion>
-Pigment dispersion 1 used in the production of the liquid developer 1: 100 parts by mass-Polyester resin 2 (copolymer consisting of 45 parts by weight of terephthalic acid and 15 parts by weight of trimellitic acid as acid units and 60 parts by weight of bisphenol A as alcohol units) Binder resin soluble in the first solvent; weight average molecular weight 25000) and tetrahydrofuran premixed in a mass ratio of 1: 1): 120 parts by mass Ajisper PB-817; Ajinomoto Fine Techno ( Co., Ltd .: 5 parts by mass The above was introduced into the liquid developer production apparatus shown in FIG. 1, and the stirring blade 3 was rotated and mixed at 100 rpm to obtain a first dispersion.

<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 215.0 mPa · s (motor torque value 0.221 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 155 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, is started to be dripped at a constant dropping rate of 9.7 ml / min. Was rotated at 20000 rpm (shear speed 37680 (1 / s)). (First stirring step)
28 minutes after the start of dropping, the first dispersion viscosity became 4.3 mPa · s (1/50 of initial viscosity, motor torque value 0.023 N · m), and at the same time, the rotational speed of the shear stirring device 4 was 5000 rpm. (Shear rate 9420 (1 / s)). (Second stirring step)
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.

<Step of obtaining third dispersion>
The shear stirrer 4 and the liquid supply port were removed from the container lid 2, the vacuum exhaust port 5 shown in FIG. 2 was attached, and vacuum exhaust was started while the stirring blade 3 continued to rotate (100 rpm). At this time, the temperature was adjusted so that the temperature of the second dispersion was 50 ° C. After 40 minutes from the start of evacuation, the inside of the reaction vessel became 500 Pa, and the evacuation was continued as it was and the atmosphere was released 60 minutes after the start of evacuation to obtain a third dispersion. The yield of the third dispersion with respect to the charged amount was 91%, which was inferior to that of the liquid developer 1, but was judged to be a satisfactory value.

<Liquid developer preparation process>
100 parts by mass of the obtained third dispersion liquid, 0.10 parts by mass of resinol S-10 (hydrogenated lecithin, manufactured by Nikko Chemicals Co., Ltd.), a poor solvent and insulating property of polyester resin 2, dipropylene glycol di 113 parts by mass of vinyl ether, 0.30 parts by mass of photopolymerization initiator (A-1), and 1 part by mass of KAYAKUURE-DETX-S (manufactured by Nippon Kayaku Co., Ltd.) were added to obtain liquid developer 2.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 2 was 0.82 μm, and coarse particles of 5 μm or more were present at a frequency of about 1 in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 3)
<Process of adjusting the first dispersion>
A first dispersion was obtained in exactly the same manner as in the production of the liquid developer 1.
<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 98.0 mPa · s (motor torque value 0.111 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 190 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, starts to be dripped at a constant drip rate of 10.3 ml / min. Was rotated at 8000 rpm (shear speed 15070 (1 / s)). (First stirring step)
26 minutes after the start of dropping, the first dispersion viscosity became 2.5 mPa · s (1/40 of initial viscosity, motor torque value 0.021 N · m), and at the same time, the rotational speed of the shear stirring device 4 was 5000 rpm. (Shear rate 9420 (1 / s)). (Second stirring step)
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 95%.
Thereafter, a liquid developer 3 was obtained in exactly the same manner as in the <liquid developer preparation step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 3 is 1.32 μm, and coarse particles of 5 μm or more exist at a frequency of about two in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 4)
<Process of adjusting the first dispersion>
A first dispersion was obtained in exactly the same manner as in the production of the liquid developer 1.
<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 98.0 mPa · s (motor torque value 0.111 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 190 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, starts to be dripped at a constant drip rate of 10.3 ml / min. Was rotated at 24000 rpm (shear speed 45220 (1 / s)). (First stirring step)
26 minutes after the start of dropping, the first dispersion viscosity was 2.5 mPa · s (1/40 of the initial viscosity,
At the same time as the motor torque value was 0.021 N · m), the rotational speed of the shear stirring device 4 was changed to 7400 rpm (shear speed 13940 (1 / s)). (Second stirring step)
In the second stirring step, the liquid flow of the mixed liquid was more turbulent than in the production of the liquid developers 1 to 3, but there was no foam and the mixed liquid was kept in a uniformly stirred state. .
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 90%, which was inferior to the production of liquid developers 1 to 3, but was an acceptable yield.
Thereafter, a liquid developer 4 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 4 was 0.83 μm, and coarse particles of 5 μm or more were present at a frequency of about 1 in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 5)
<Process of adjusting the first dispersion>
A first dispersion was obtained in exactly the same manner as in the production of the liquid developer 2.
<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 215.0 mPa · s (motor torque value 0.221 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 155 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, is started to be dripped at a constant dropping rate of 9.7 ml / min. Was rotated at 20000 rpm (shear speed 37680 (1 / s)). (First stirring step)
24 minutes after the start of dropping, the first dispersion viscosity became 5.4 mPa · s (1/40 of the initial viscosity, motor torque value 0.024 N · m), and at the same time, the rotation of the shear stirring device 4 was stopped. . (Shear rate 0 (1 / s)) (second stirring step)
In the second stirring step, the disturbance of the liquid flow of the mixed liquid was gentle, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 2. The yield of the third dispersion was 94%, which was sufficiently high.
Thereafter, a liquid developer 5 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 2.
The toner particles constituting the liquid developer 5 had a volume average particle diameter (Mv) of 0.81 μm, and no coarse particles of 5 μm or more were observed. (Evaluation A)

(Manufacture of liquid developer 6)
<Process of adjusting the first dispersion>
A first dispersion was obtained in exactly the same manner as in the production of the liquid developer 2.
<Step of obtaining second dispersion>
A homomixer Mark II2.5 type manufactured by Primix Co., Ltd. was introduced as the shear stirring device 4 in the liquid developer production apparatus shown in FIG. It was 215.0 mPa · s (motor torque value 0.221 N · m) of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm. The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 190 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, starts to be dripped at a constant drip rate of 10.3 ml / min. Was rotated at 10,000 rpm (shear speed 26170 (1 / s)). (First stirring step)
26 minutes after the start of dropping, the first dispersion viscosity became 5.4 mPa · s (1/40 of initial viscosity, motor torque value 0.024 N · m) and at the same time, the rotational speed of the shear stirring device 4 was 5000 rpm. (Shear rate 13080 (1 / s)). (Second stirring step)
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 94%, which was sufficiently high.
Thereafter, a liquid developer 6 was obtained in exactly the same manner as in the <liquid developer preparation step> in the production of the liquid developer 1.
The toner particles constituting the liquid developer 6 had a volume average particle diameter (Mv) of 0.85 μm, and no coarse particles of 5 μm or more were observed. (Evaluation A)

(Manufacture of liquid developer 7)
<Process of adjusting the first dispersion>
A first dispersion was obtained in exactly the same manner as in the production of the liquid developer 1.
<Step of obtaining second dispersion>
As a shear stirrer 4 in the liquid developer production apparatus shown in FIG. 1, TALAX T25 manufactured by IKA Japan Co., Ltd. was introduced. The initial viscosity of the first dispersion calculated from the motor torque value of the stirring blade 3 maintaining the rotation speed of 100 rpm was 98.0 mPa · s (motor torque value 0.111 N · m). The initial temperature of the first dispersion was adjusted to 20 ° C.
From the liquid supply port (not shown in FIG. 1), 190 parts by mass of insulating liquid dodecyl vinyl ether (DDVE), which is a poor solvent for the polyester resin 1, starts to be dripped at a constant drip rate of 10.3 ml / min. Was rotated at 24000 rpm (shear speed 45220 (1 / s)). (First stirring step)
23 minutes after the start of dropping, the first dispersion viscosity became 19.6 mPa · s (1/5 of initial viscosity, motor torque value 0.037 N · m), and at the same time, the rotational speed of the shear stirring device 4 was 5000 rpm. (Shear rate 9420 (1 / s)). (Second stirring step)
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 94%.
Thereafter, a liquid developer 7 was obtained in exactly the same manner as in the <liquid developer preparation step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 7 is 1.02 μm, and coarse particles of 5 μm or more exist at a frequency of about 1 in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 8)
In the second stirring step of <the step of obtaining the second dispersion> in the production of the liquid developer 5, the liquid development is performed except that the rotational speed of the shear stirring device 4 is 7600 rpm (shear speed 14320 (1 / s)). The process up to the second stirring step was performed in exactly the same manner as in the preparation of Agent 5.
In the mixed liquid in the second stirring step, the liquid flow of the mixed liquid was slightly disturbed, and some bubbling was observed.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 2. The yield of the third dispersion was 86%, which was an acceptable yield.
Thereafter, a liquid developer 8 was obtained in exactly the same manner as in the <liquid developer preparation step> in the production of the liquid developer 2.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 8 was 0.85 μm, and coarse particles of 5 μm or more existed at a frequency of about two in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 9)
In the first stirring step of <the step of obtaining the second dispersion> in the production of the liquid developer 1, the liquid development is performed except that the rotational speed of the shear stirring device 4 is 7800 rpm (shear speed 14700 (1 / s)). The process up to the second stirring step was performed in exactly the same manner as in the preparation of Agent 1.
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 94%, which was sufficiently high.
Thereafter, a liquid developer 9 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 9 is 1.45 μm, and coarse particles of 5 μm or more exist at a frequency of about two in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 10)
In the second stirring step of <the step of obtaining the second dispersion> in the production of the liquid developer 1, the liquid is used except that the rotational speed of the shear stirring device 4 is not changed from 24000 rpm (shear speed 45220 (1 / s)). The process up to the second stirring step was performed in exactly the same manner as in the production of Developer 1.
In the second stirring step, the liquid flow of the mixed liquid was greatly disturbed, foaming occurred, and the mixed liquid was scattered outside the system.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 75%, which was extremely inferior.
Thereafter, a liquid developer 10 was obtained in exactly the same manner as in the <liquid developer preparation step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 10 is 0.83 μm, and coarse particles of 5 μm or more exist at a frequency of about 10 in one field of view of 1000 times. (Evaluation C)

(Manufacture of liquid developer 11)
From the first stirring step of <the step of obtaining the second dispersion> in the production of the liquid developer 1, the rotational speed of the shear stirring device 4 is set to 7400 rpm (shear speed 13940 (1 / s)). The second stirring step was performed in exactly the same manner as in the production of the liquid developer 1 except that the rotational speed was not changed.
In the second stirring step, there was little disturbance in the liquid flow of the mixed liquid, no bubbles were formed, and the mixed liquid was maintained in a uniformly stirred state.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 91%.
Thereafter, a liquid developer 11 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 11 is 1.62 μm, and coarse particles of 5 μm or more exist at a frequency of about two in one field of view of 1000 times. (Evaluation B)

(Manufacture of liquid developer 12)
In <the step of obtaining the second dispersion> in the production of the liquid developer 1, after 45 minutes from the start of the first stirring step, the viscosity of the first dispersion is 1.0 mPa · s (1/100 of the initial viscosity, motor (Torque value 0.020 N · m) At the same time, the rotational speed of the shear stirring device 4 was changed to 5000 rpm (shear speed 9420 (1 / s)). (Second stirring step)
From the latter half of the first stirring step, the liquid flow of the mixed liquid was greatly disturbed, foaming occurred, and the mixed liquid was scattered outside the system.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. The yield of the third dispersion was 82%, which was not sufficient.
Thereafter, a liquid developer 12 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 12 is 0.83 μm, and coarse particles of 5 μm or more exist at a frequency of about 10 in one field of view of 1000 times. (Evaluation C)

(Manufacture of liquid developer 13)
In <the step of obtaining the second dispersion> in the production of the liquid developer 1, after 10 minutes from the start of the first stirring step, the viscosity of the first dispersion is 24.5 mPa · s (¼ of the initial viscosity, motor (Torque value 0.042 N · m) At the same time, the rotational speed of the shear stirring device 4 was changed to 5000 rpm (shear speed 9420 (1 / s)). (Second stirring step)
In the second stirring step, the liquid flow of the mixed liquid was less disturbed, but coarse particles that could be visually observed were observed.
The dropping was finished 60 minutes after the start of dropping to obtain a second dispersion.
Thereafter, a third dispersion was obtained in exactly the same manner as in <Process for obtaining third dispersion> in the production of liquid developer 1. Even in <the step of obtaining the third dispersion>, foaming of the mixture was observed. The yield of the third dispersion was 94%.
Thereafter, a liquid developer 13 was obtained in exactly the same manner as in the <liquid developer preparing step> in the production of the liquid developer 1.
The volume average particle diameter (Mv) of the toner particles constituting the liquid developer 13 could not be measured with a particle size distribution meter, and many coarse particles of 5 μm to 20 μm were observed. (Evaluation C)

Example 1
The liquid developer 1 was introduced into the image forming apparatus shown in FIG. 3, and the dot reproducibility of the fixed image was evaluated.
The configuration of the image forming apparatus used in this embodiment will be described below.
The liquid developer 1 was charged into the 100 g developer tank 16 as a uniform concentration solution. The liquid developer 1 is applied to the supply roller 15 adjusted to a predetermined potential and is carried to the developing roller 13. The liquid developer 1 that has moved to the developing roller 13 is adjusted to a desired developer concentration (25 to 35 mass%) by the squeegee roller 14 and is carried to the developing nip between the developing roller 13 and the photosensitive drum 10.
The photosensitive drum 10 was an amorphous silicon drum, and the surface was charged to −600 V by a charger 11 upstream of the developing nip. After charging, a latent image of one dot and one space of 600 dpi was formed by the exposure device 12 so that the potential of the image portion was −200V. The peripheral speed of the photosensitive drum was 700 mm / s.
A bias of −400 V is applied to the developing roller 13, and the negatively charged developer selectively moves to the image portion. The carrier liquid is separated into both the developing roller 13 and the photosensitive drum 10 at the developing nip portion. Therefore, the developer concentration is sent to the subsequent process while becoming higher.
A voltage of +200 V was applied to the intermediate transfer roller 17 to primarily transfer the developer developed on the latent image portion on the photosensitive drum 10.
The toner particles and carrier liquid remaining on the photosensitive drum 10 are scraped off by the cleaning blade 21.
A voltage of +1000 V was applied to the secondary transfer roller 18, and the developer on the intermediate transfer roller 17 was secondarily transferred to a medium 20 such as paper held on the secondary transfer roller 18.
The developer on the second-transferred medium is accompanied by a small amount of carrier liquid, and the carrier liquid is cured by ultraviolet rays, so that the image is fixed on the medium by irradiation with ultraviolet rays. In this embodiment, the curing lamp 19 is an ultraviolet irradiation device having an illuminance peak in the wavelength range of 385 ± 5 nm. The fixing process was performed by the media passing under the curing lamp 19.
The image in this example using the liquid developer 1 was A evaluation in dot reproducibility evaluation, high uniformity, smooth and excellent image quality.

(Example 2)
The obtained liquid developer 2 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was inferior to that of Example 1 and the image quality was satisfactory for practical use although it was evaluated as B.
(Example 3)
The obtained liquid developer 3 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was slightly different from that in Example 1 in the dot shape. The dot reproducibility evaluation was B evaluation.

Example 4
The obtained liquid developer 4 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was slightly lower than that of Example 1. The dot reproducibility evaluation was B evaluation.
(Example 5)
The obtained liquid developer 5 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was excellent as in Example 1, and the evaluation was A.

(Example 6)
The obtained liquid developer 6 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was excellent as in Example 1, and the evaluation was A.
(Example 7)
The obtained liquid developer 7 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, the image quality was lower than that of Example 1. The dot reproducibility evaluation was B evaluation.

(Example 8)
The obtained liquid developer 8 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, it was possible to recognize the dots although scattering was observed, and the C evaluation was made.
Example 9
The obtained liquid developer 9 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, although it was greatly inferior to Example 1, it was possible to recognize dots, and C evaluation was made.

(Comparative Example 1)
The obtained liquid developer 10 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, many missing dots and scattering were observed. The dot reproducibility evaluation was D evaluation.
(Comparative Example 2)
The obtained liquid developer 11 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, there were many portions where the image density was uneven and could not be recognized as dots. The dot reproducibility evaluation was D evaluation.

(Comparative Example 3)
The obtained liquid developer 12 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1, and dot reproducibility was evaluated in the same manner as in Example 1.
As a result, many missing dots and scattering were observed. The dot reproducibility evaluation was D evaluation.
(Comparative Example 4)
The obtained liquid developer 13 was introduced into the image forming apparatus shown in FIG. 1 in the same manner as in Example 1. However, the toner particles carried to the developing nip between the developing roller 13 and the photosensitive drum 10 were remarkably small, and the image evaluation was It was impossible.
Table 1 summarizes the developer evaluation results and dot reproducibility evaluation results of the above examples and comparative examples.

1: reaction container, 2: container lid, 3: stirring blade, 4: shear stirring device, 5: vacuum exhaust port, 10: photosensitive drum, 11: charger, 12: exposure device, 13: developing roller, 14: squeegee roller , 15: supply roller, 16: developer tank, 17: intermediate transfer member, 18: secondary transfer roller, 19: curing lamp, 20: medium, 21: cleaning blade

Claims (3)

(1) A step of preparing a first dispersion in which the pigment is dispersed by mixing a pigment, a first solvent, and a binder resin soluble in the first solvent;
(2) A second solvent, which is a poor solvent for the binder resin, is added to the first dispersion liquid to precipitate particles of the binder resin containing the pigment, and the second particles are dispersed. And (3) a third dispersion in which the first solvent is distilled off from the second dispersion, and the particles are dispersed in a liquid containing the second solvent. A method of producing a liquid developer, comprising the step of obtaining a liquid,
The second solvent is electrically insulating;
The step of obtaining the second dispersion includes a first stirring step of shearing and stirring the first dispersion at a first speed range, and a shearing of the dispersion after the first stirring step at a second speed range. A second stirring step of stirring,
The average value of the shear rate in the first speed range is faster than the average value of the shear rate in the second speed range,
In the step of obtaining the second dispersion, when the viscosity of the first dispersion becomes 1/50 or more and 1/5 or less of the viscosity at the start of the step of obtaining the second dispersion. A method for producing a liquid developer, wherein the process is shifted from the stirring step to the second stirring step.   In the step of obtaining the second dispersion, the average value of the shear rate in the first speed range is 15000 (1 / s) or more, and the average value of the shear rate in the second speed range is 0 (1 2. The method for producing a liquid developer according to claim 1, wherein the liquid developer is 1 / s or more and 14000 (1 / s) or less. An apparatus for producing a liquid developer comprising at least particles containing a pigment and a binder resin, and an insulating liquid which is a poor solvent for the binder resin,
A means for adding and mixing the insulating liquid while stirring the dispersion containing the pigment and binder resin, and a means for monitoring the viscosity of the dispersion during stirring.
An apparatus for producing a liquid developer, comprising a mechanism for changing a stirring speed in accordance with a change in a monitored value of viscosity.

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