JP2006309037A - Method for manufacturing liquid developer and liquid developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid developer excellent in charging and fixing characteristics, and to provide a method for manufacturing a liquid developer by which such a liquid developer can be efficiently manufactured, particularly to provide a liquid developer excellent in charging and fixing characteristics in an environmentally friendly way. <P>SOLUTION: The method for manufacturing a liquid developer manufactures a liquid developer in which toner particles are dispersed in an insulating liquid, and comprises: a step of preparing a dispersion in which a dispersoid consisting of materials including a resin material and a colorant is dispersed in a dispersion medium; a dispersion medium removing step of removing the dispersion medium by spraying the dispersion as droplets to obtain dry fine particles; and a dispersion step of dispersing the dry fine particles in an insulating liquid, wherein the colorant is a colorant in which pigment particles having a cationic group on the surface are coated with a polymer having a repeating structural unit derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group and a polymerizable group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

A dry toner method in which a toner composed of a material containing a colorant such as a pigment and a binder resin is used in a dry state as a developer used to develop the electrostatic latent image formed on the latent image carrier. And a method using a liquid developer in which toner is dispersed in an electrically insulating carrier liquid.
The method using dry toner handles solid-state toner, so there are advantages in handling, but there are concerns about adverse effects on the human body due to powder, as well as contamination due to scattering of toner, and when toner is dispersed There is a problem with uniformity. Further, the dry toner has a problem that the particles are likely to aggregate and it is difficult to sufficiently reduce the size of the toner particles, and it is difficult to form a toner image with high resolution. In addition, when the size of the toner particles is relatively small, the problem due to the powder as described above becomes more remarkable.

On the other hand, in the method using the liquid developer, the toner particles are effectively prevented from aggregating in the liquid developer, so that it is possible to use fine toner particles, and the binder resin has a low softening point. (Low softening temperature) can be used. As a result, in the method using a liquid developer, fine line image reproducibility is good, gradation reproducibility is good, color reproducibility is excellent, and it is also excellent as a high-speed image forming method. It has characteristics.
Conventionally, a liquid developer has conventionally been obtained by pulverizing a resin to produce a toner (see, for example, Patent Document 1), and polymerizing a monomer component in the electrically insulating liquid, thereby forming the electrically insulating liquid. It has been produced by a polymerization method for forming insoluble resin fine particles (for example, see Patent Document 2).

However, the conventional method for producing a liquid developer has the following problems.
That is, in the pulverization method, it is difficult to pulverize the toner particles to a sufficiently small size (for example, 5 μm or less), and the effect of using the liquid developer as described above is sufficiently increased. In order to make it a size that can be exhibited, a very long grinding energy was required for a very long time, and the productivity of the liquid developer was extremely low. Further, in the pulverization method, the particle size distribution of the toner particles tends to be wide (the variation in particle size is large), and the shape of the toner particles tends to be irregular and non-uniform. As a result, the variation in characteristics (for example, charging characteristics) among the toner particles tends to increase.

Also, in the polymerization method, it is difficult to make the conditions for the polymerization reaction suitable, so that a resin material having a suitable molecular weight can be formed, toner particles having a desired size can be formed, It is difficult to reduce the variation sufficiently. As a result, the stability and reliability of the toner quality tends to be low. Further, in the polymerization method, it takes a relatively long time to form toner particles, and the productivity of the liquid developer is poor.
In addition, with a liquid developer produced by a conventional method, it is difficult to stabilize the charge amount, and problems such as a decrease in image density and fogging are likely to occur. Further, since the colorant contained in the conventional toner particles has a low affinity for the recording medium, there is a problem that the fixing property of the toner particles to the recording medium is hindered depending on the content.

JP-A-7-234551 Japanese Patent Publication No.8-7470

  An object of the present invention is to provide a liquid developer excellent in charging characteristics and fixing characteristics, and to provide a method for producing a liquid developer capable of efficiently producing such a liquid developer. is there.

Such an object is achieved by the present invention described below.
The method for producing a liquid developer of the present invention is a method for producing a liquid developer in which toner particles are dispersed in an insulating liquid,
Preparing a dispersion in which a dispersoid composed of a resin material and a material containing a colorant is dispersed in a dispersion medium;
A step of removing the dispersion medium by spraying the dispersion as droplets to obtain a dry fine particle;
A dispersion step of dispersing the dry fine particles in an insulating liquid,
As the colorant, pigment particles having a cationic group on the surface are coated with a polymer having a repeating structural unit derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group, and a polymerizable group. It is characterized by using the same.
Thereby, a liquid developer excellent in charging characteristics and fixing characteristics can be provided.

In the method for producing a liquid developer of the present invention, the colorant is obtained by polymerizing the anionic polymerizable surfactant in an aqueous dispersion in which pigment particles having the cationic group on the surface are dispersed. The pigment particles are preferably coated with a polymer.
As a result, the charge on the surface of the pigment particles can be surely canceled by the anionic group derived from the anionic polymerizable surfactant, and the electrical stability of the entire liquid developer can be obtained.

これにより、着色剤の耐久性が向上し、例えば、液体現像剤を製造する際に、顔料を被覆するポリマーの不本意な剥がれ等を効果的に防止することができる。 In the method for producing a liquid developer of the present invention, it is preferable that the polymer further has a repeating structural unit derived from a hydrophobic monomer.
Thereby, the durability of the colorant is improved, and, for example, when the liquid developer is produced, unintentional peeling of the polymer covering the pigment can be effectively prevented.
In the method for producing a liquid developer of the present invention, the polymer further has a repeating structural unit derived from a crosslinkable monomer and / or a repeating structural unit derived from a monomer represented by the following general formula (1). Is preferred.

Thereby, the durability of the colorant is improved, and, for example, when the liquid developer is produced, unintentional peeling of the polymer covering the pigment can be effectively prevented.

In the method for producing a liquid developer of the present invention, the pigment constituting the pigment particles is preferably carbon black.
Carbon black has a strong tendency to inhibit the charging characteristics and fixing characteristics of the liquid developer, but by using the microencapsulated one, it is possible to prevent the charging characteristics and fixing characteristics of the liquid developer from being inhibited. .

In the method for producing a liquid developer of the present invention, the cationic group of the pigment particle is a group consisting of a primary amine cation group, a secondary amine cation group, a tertiary amine cation group, and a quaternary ammonium cation group. It is preferable that it is selected from.
As a result, a liquid developer excellent in charging characteristics and fixing characteristics can be provided more easily.

In the method for producing a liquid developer of the present invention, the anionic group of the anionic polymerizable surfactant includes a sulfonate anion group (—SO ₃ ⁻ ), a sulfinate anion group (—RSO ₂ ^— : R is C _1). it is preferably those selected from the group consisting ^of) - alkyl or phenyl and modified bodies -C _12), a carboxylate anion group (-COO.
As a result, a liquid developer excellent in charging characteristics and fixing characteristics can be provided more easily.

In the method for producing a liquid developer of the present invention, the hydrophobic group of the anionic polymerization surfactant is preferably selected from the group consisting of an alkyl group, an aryl group, and a group in which these are combined.
As a result, a liquid developer excellent in charging characteristics and fixing characteristics can be provided more easily.

In the method for producing a liquid developer of the present invention, the polymerizable group of the anionic polymerization surfactant is an unsaturated hydrocarbon group capable of radical polymerization, and includes a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, It is preferably one selected from the group consisting of a propenyl group, a vinylidene group, and a vinylene group.
As a result, a liquid developer excellent in charging characteristics and fixing characteristics can be provided more easily.

In the method for producing a liquid developer of the present invention, the colorant is added to the aqueous dispersion of pigment particles having a cationic group on the surface thereof, and the anionic polymerizable surfactant is added to the aqueous dispersion, followed by mixing, and then the anionic polymerization. It is preferably obtained by adding a surfactant and emulsifying, then adding a polymerization initiator and polymerizing in water.
As a result, the charge on the surface of the pigment particles can be canceled by the anionic group derived from the anionic polymerizable surfactant, and the electrical stability of the entire liquid developer can be obtained.

In the method for producing a liquid developer of the present invention, the colorant is prepared by adding the anionic polymerizable surfactant to an aqueous dispersion of pigment particles having the cationic group on the surface and mixing the mixture, and then adding the hydrophobic monomer and the It is preferably obtained by adding an anionic polymerizable surfactant and mixing, emulsifying, adding a polymerization initiator and polymerizing in water.
As a result, the durability of the colorant can be improved more effectively, and the charge on the surface of the pigment particles can be more reliably canceled out by the anionic group derived from the anionic polymerizable surfactant, and the liquid development The electrical stability as the whole agent can be obtained more effectively.

これにより、着色剤の耐久性をより効果的に向上させることができるとともに、顔料粒子表面の電荷を、アニオン性重合性界面活性剤由来のアニオン性基によってより確実に打ち消すことができ、液体現像剤全体としての電気的安定性をより効果的に得ることができる。 In the method for producing a liquid developer of the present invention, the colorant is mixed with the hydrophobic monomer after adding the anionic polymerizable surfactant to the aqueous dispersion of the pigment particles having the cationic group on the surface and mixing. And / or the monomer represented by the following general formula (1) and the anionic polymerizable surfactant are added and mixed, and after emulsification, a polymerization initiator is added and polymerization is performed in water. It is preferable.

As a result, the durability of the colorant can be improved more effectively, and the charge on the surface of the pigment particles can be more reliably canceled out by the anionic group derived from the anionic polymerizable surfactant, and the liquid development The electrical stability as the whole agent can be obtained more effectively.

In the method for producing a liquid developer of the present invention, it is preferable that the droplets are sprayed using a piezoelectric pulse in the dispersion medium removing step.
Thereby, a liquid developer excellent in charging characteristics and fixing characteristics can be obtained efficiently.
The liquid developer of the present invention is manufactured by the method of the present invention.
Thereby, it is possible to easily provide a liquid developer excellent in charging characteristics and fixing characteristics.

The liquid developer of the present invention preferably contains a charge control agent.
The contact between the colorant and the charge control agent may inhibit the function of the charge control agent. However, in the liquid developer finally obtained by using microencapsulated pigment as the colorant, In addition, since the colorant and the charge control agent can be present in a state where they are not in direct contact with each other, the obtained liquid developer has excellent charging characteristics while maintaining excellent color developability.

Hereinafter, preferred embodiments of the liquid developer of the present invention will be described in detail with reference to the accompanying drawings.
FIGS. 1 and 3 are diagrams showing a production process of a colorant applied to the liquid developer of the present invention, and FIGS. 2 and 4 are diagrams showing an example of a microencapsulated pigment applied to the toner of the present invention. FIG. 5 is a longitudinal sectional view schematically showing an example of the configuration of a kneader and a cooler for producing a kneaded product used for the preparation of an aqueous emulsion (aqueous dispersion), and FIG. 6 is a liquid of the present invention. FIG. 7 is a longitudinal sectional view schematically showing a preferred embodiment of a dry fine particle production apparatus used for producing a developer, and FIG. 7 is an enlarged cross-sectional view of the vicinity of the head portion of the dry fine particle production apparatus shown in FIG. Hereinafter, in FIG. 5, the left side is assumed to be “base end” and the right side is assumed to be “tip”.

<Constituent material of toner particles>
First, constituent materials of toner (toner particles) constituting the liquid developer will be described.
The toner particles include at least a binder resin (resin) and a colorant.
1. Resin (binder resin)
In the present invention, the resin (binder resin) is not particularly limited, and for example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer. Polymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester -Styrene resins such as methacrylic acid ester copolymer, styrene-α-chloroacrylic acid methyl copolymer, styrene-acrylonitrile-acrylic acid ester copolymer, styrene-vinyl methyl ether copolymer, etc. A homopolymer or copolymer, Polyester resin, epoxy resin, urethane modified epoxy resin, silicone modified epoxy resin, vinyl chloride resin, rosin modified maleic acid resin, phenyl resin, polyethylene resin, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl Examples include acrylate copolymers, xylene resins, polyvinyl butyral resins, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins. One or more of these can be used in combination.

  Although the softening temperature of resin (resin material) is not specifically limited, It is preferable that it is 50-130 degreeC, It is more preferable that it is 50-120 degreeC, It is further more preferable that it is 60-115 degreeC. In the present specification, the softening temperature is a measurement condition in a Koka type flow tester (manufactured by Shimadzu Corporation): temperature increase rate: 5 ° C./min, softening start temperature defined by a die hole diameter of 1.0 mm. Point to.

2. Colorant The toner particles contain a colorant.
The colorant used in the liquid developer of the present invention is a repetitive pigment particle having a cationic group on its surface derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group and a polymerizable group. A pigment coated with a polymer having a structural unit, that is, a microencapsulated pigment (hereinafter also simply referred to as a microencapsulated pigment).

As shown in FIG. 2, the microencapsulated pigment 100 includes an anion of a polymer (polymer layer) 60 derived from a cationic group 14 on the surface of the pigment particle 1 and an anionic polymerizable surfactant as described later. The pigment particles 1 are covered with the polymer layer 60 in a state in which the functional group is ionically bonded.
By the way, with a conventional liquid developer, it is difficult to stabilize the charge amount, and problems such as a decrease in image density and fogging are likely to occur. The reason for this is that pigments used as colorants usually have a cationic group on the surface to prevent poor dispersion in the resin due to agglomeration. Since many of them degrade the electrical characteristics (charging characteristics) of the particles, it is difficult to control the charge amount of the toner particles reliably even if the resin is selected. It is thought to be because of this. In addition, it is considered that even when a charge control agent is added to improve the charge characteristics, the charge control agent and the colorant come into contact with each other, and it is difficult to control the charge amount.

In contrast, by using the microencapsulated pigment as described above as the colorant, the charge on the surface of the pigment particles is canceled by the anionic group derived from the anionic polymerizable surfactant. Stable. As a result, a liquid developer having excellent charging characteristics (particularly charging stability) can be obtained.
In addition, the colorant used in the conventional liquid developer has low affinity with the recording medium, and depending on the content, the fixing property of the toner particles is hindered. As a result, the affinity of the pigment itself to the recording medium is improved, so that the fixing characteristics of the toner particles are improved.

  Further, by using the encapsulated pigment as described above, the affinity with the above-described resin is improved and the dispersibility in the resin is improved. As a result, the variation in the content of the colorant among the toner particles can be reduced, and the color developability is improved. Further, conventionally used colorants have a low affinity for the resin if the content in the toner particles is too high, which has reduced the durability of the toner particles. By using the pigment, it is possible to prevent a decrease in the durability of the toner particles even when the content in the toner particles is increased.

In addition, since the colorant conventionally used in liquid developers has a polar group (cationic group) on the surface, toner particles containing such a colorant are affected by moisture in the air. Although it is easily received and has low environmental stability, the use of the microencapsulated pigment as described above as a colorant can improve the environmental stability because the surface is electrically neutral.
In addition, since the pigment particles and the polymer are strongly electrically bonded, it is possible to prevent the polymer from unintentionally peeling off from the pigment surface, and it is possible to reliably prevent deterioration in charging characteristics. .

  Further, for example, when a charge control agent is contained in the toner particles, depending on the type of the colorant (particularly in the case of carbon black), the contact between the colorant and the charge control agent may Although the function may be hindered, by using a microencapsulated pigment as a colorant, the colorant and the charge control agent may be present in a state where they are not in direct contact with the toner particles finally obtained. Therefore, the finally obtained liquid developer has excellent charging properties while maintaining excellent color developability.

In addition, such encapsulated pigments are formed by electrically bonding the cationic groups on the surface of the pigment particles and the anionic groups of the surfactant. It can be small.
The average particle diameter of these microencapsulated pigments is preferably 400 nm or less, more preferably 300 nm or less, and even more preferably 20 to 200 nm. If the average particle size of the microencapsulated pigment is too large, it may be difficult to make the content of the colorant uniform among the toner particles depending on the size of the toner particles. The description of the particle size is described by the measured value of the laser light scattering method.)

  Further, the aspect ratio (long and short) of the microencapsulated pigment is 1.0 to 1.3, and the Zingg index is 1.0 to 1.3 (more preferably 1.0 to 1.2). It is preferable that Thereby, the dispersibility in the resin is improved, and even when the colorant (microencapsulated pigment) is present on the surface of the toner particles, the influence on the shape of the toner can be reduced. As a result, a toner with less variation in shape can be provided.

  When the short diameter of the microencapsulated pigment particles is b, the long diameter is l, and the thickness is t (l ≧ b ≧ t> 0), the aspect ratio (long / short) is 1 / b (≧ 1), and the flatness is b / t (≧ 1), Zingg index = long / shortness / flatness = (l · t) / b2. That is, the true sphere has an aspect ratio of 1 and a Zingg index of 1.

  When the Zingg index is larger than 1.3, the microencapsulated pigment becomes flatter and becomes less isotropy. Therefore, when the microencapsulated pigment is present on the surface of the toner particle, the shape of the toner particle is changed. May have an impact. The method for setting the aspect ratio and Zingg index within the above ranges is not particularly limited. However, a microencapsulated pigment in which pigment particles having a cationic group on the surface are coated with a polymer by the above-described emulsion polymerization method can easily satisfy this condition. Can meet.

In addition, in a microencapsulated pigment produced by a method other than an emulsion polymerization method such as an acid precipitation method or a phase inversion emulsification method, which will be described later, the aspect ratio and the Zingg index are unlikely to fall within the above ranges.
When the microencapsulated pigment is in the above aspect ratio and Zingg index range, it becomes a spherical shape. This improves the dispersibility in the resin, and the colorant (microencapsulated pigment) is a toner. Even when it is present on the particle surface, the influence on the toner shape and the like can be reduced. As a result, a toner with less variation in shape can be provided.

Next, the constituent components of the macroencapsulated pigment will be described in detail.
(2-1) Pigment particles 1
Examples of the pigment constituting the microencapsulated pigment used in the present invention include inorganic pigments and organic pigments.
In general, an amine substituent (primary amine, secondary amine, tertiary amine), quaternary ammonium group (—NR ₃ ⁺ ), quaternary phosphonium group (—PR ₃ ) is formed on the surface of the pigment particle. ⁺ ), And a cationic group such as a sulfonium group (—SR ₂ ⁺ ) or a pyridinium group. However, by encapsulating as described above, the surface of the pigment particles can be made electrically stable (neutral). As a result, the charging characteristics of the finally obtained liquid developer can be improved.

  Examples of such inorganic pigments include carbon blacks such as furnace black, lamb black, acetylene black, and channel black (C.I. pigment black 7), iron oxide pigments, and the like. Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxanes). Pigments, thioindigo pigments, isoindolinone pigments, or quinofuranone pigments), dye chelates (for example, basic dye-type chelates or acidic dye-type chelates), nitro pigments, nitroso pigments, or aniline black.

  More specifically, as an inorganic pigment used for black, the following carbon black, for example, No. manufactured by Mitsubishi Chemical Corporation is used. 2300, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, or No2200B, etc .; Columbia-made Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc .; 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc .; or Color Black FW1, Col Black FW2, Col FW2V, Col 200 or Black S150, Color Black S160, Color Black S170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6, Special Black 5, Special Black 4A, and SpecialBlack 4, and the like.

In particular, since carbon black as described above has a strong tendency to inhibit the charging characteristics and fixing characteristics of the liquid developer, the effect of the present invention by microencapsulation appears significantly.
Examples of the organic pigment for black include black organic pigments such as aniline black (C.I. Pigment Black 1).
Examples of organic pigments for yellow toner include C.I. l. Pigment Yellow 1 (Hansa Yellow), 2, 3 (Hansa Yellow 10G), 4, 5 (Hansa Yellow 5G), 6, 7, 10, 11, 12, 13, 14, 16, 17, 24 (Flavantron Yellow) , 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108 (anthrapyrimidine yellow), 109, 110, 113, 117 ( (Copper complex pigment), 120, 124, 128, 129, 133 (quinophthalone), 138, 139 (isoindolinone), 147, 151, 153 (nickel complex pigment), 154, 167, 172, 180, and the like.

  Further, organic pigments for magenta toner include C.I. l. Pigment Red 1 (Paral Red), 2, 3 (Toluidine Red), 4, 5 (lTR Red), 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21 , 22, 23, 30, 31, 32, 37, 38 (pyrazolone red), 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 88 (thioindigo), 112 (Naphthol AS series), 114 (Naphthol AS series), 122 (Dimethylquinacridone), 123, 144, 146, 149, 150, 166, 168 (Antanthrone orange), 170 (Naphthol AS series), 171, 175, 176 , 177, 178, 179 (berylene maroon), 184, 185, 187, 202, 209 (dichloroquinacridone), 219, 224 (berylene), 245 (naphthol AS yarn) ) Or C.I. I. Pigment violet 19 (quinacridone), 23 (dioxazine violet), 32, 33, 36, 38, 43, 50 and the like.

Furthermore, as organic pigments for cyan toner, C.I. l. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16 (metal-free phthalocyanine), 18 (alkali blue toner), 22, 25, 60 ( Slen Blue), 65 (Biolantron), 66 (Indigo), C.I. l. Vat blue 4, 60 etc. are mentioned.
Furthermore, as organic pigments used for color toners other than magenta, cyan or yellow toners, C.I. I. Pigment green 7 (phthalocyanine green), 10 (green gold), 36, 37; C.I. I. Pigment brown 3, 5, 25, 26; I. Pigment orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, and the like.

In the macroencapsulated pigment used in the liquid developer of the present invention, the above pigments can be used alone or in combination of two or more.
The average particle diameter of the pigment particles having such a cationic group on the surface is preferably 150 nm or less, and preferably 20 nm to 80 nm. Thereby, the average diameter of a microencapsulated pigment can be made suitable.

  Even if the pigment particles are electrically neutral or negatively charged and coated with a conventional resin material, the effect of the present invention cannot be obtained. For example, in the former case, since the average particle diameter of the pigment particles varies due to aggregation of the pigment particles, etc., the content of each toner component among the toner particles may vary. As a result, characteristics such as charging characteristics and fixing characteristics vary. In the latter case, for example, the colorant inhibits the electrical stability of the toner particles, and the charging characteristics of the liquid developer cannot be sufficiently obtained.

  The cationic group may be introduced later. That is, pigment particles having no cationic group or those having a cationic group introduced on the surface of pigment particles having an anionic group may be used. In such a case, a known pigment having no cationic group on the surface or pigment particles having an anionic group can be used as a material for the microencapsulated pigment. Thereby, the variation of the color which can be expressed can be increased.

Examples of the method for introducing a cationic group include the following methods.
The introduction of the cationic group can be performed, for example, by adding an aromatic group to the pigment by diazotization using a diazonium salt and replacing the pigment with a cationic group. Specifically, it can be prepared by reacting a pigment with a diazonium salt in a liquid reaction medium to bond at least one organic ionic group to the pigment surface. The diazonium salt can have an organic ionic group that is bonded to the carbon black.

  A diazonium salt is an organic compound having one or more diazonium groups. Diazonium salts are typically diazotizing agents such as ammonium nitrite, butyl nitrite, dicyclohexylammonium nitrite, ethyl nitrite, isoamyl nitrite, lithium nitrite, sodium nitrite, potassium nitrite, or zinc nitrite. Any metal or organic nitrite, and can include nitrous acid, nitric oxide, nitrogen dioxide, and mixtures thereof) and is generated by reacting the treating agent / reactant at suitable conditions. The cationic treatment agent itself can contain nitrite, in which case the diazonium salt is made by subsequent addition of acid. Thus, the treating agent can include a diazotizing agent (eg, nitrite) that can be made into a diazonium salt by adding an acid.

  For the method of introducing a cationic group on the surface, WO96 / 18688, US Pat. No. 5,554,739, WO96 / 18696, US Pat. Nos. 5,851,280, 5,837, No. 045, No. 5,803,959, No. 5,672,198, No. 5,571,311, No. 5,630,868, No. 5,707,432, No. No. 5,803,959, No. 5,698,016, No. 5,713,988, WO 97/47697, WO 97/47699.

(2-2) Polymer layer 60
The polymer layer 60 is composed of a polymer derived from an anionic polymerizable surfactant.
Examples of the anionic polymerizable surfactant used in the present invention include anions as described in JP-B-49-46291, JP-B-1-24142, or JP-A-62-104802. Allyl derivatives, anionic propenyl derivatives as described in JP-A-62-221431, JP-A-62-34947 or JP-A-55-11525 Examples thereof include anionic acrylic acid derivatives and anionic itaconic acid derivatives as described in JP-B-46-34898 or JP-A-51-30284.
As a specific example of the anionic polymerizable surfactant used in the present invention, the general formula (31):

で表される化合物、または、式（３２）：

Or a compound represented by formula (32):

で表される化合物が好ましい。

The compound represented by these is preferable.

  The polymerizable surfactant represented by the formula (31) is described in JP-A-5-320276 or JP-A-10-316909. By appropriately adjusting the type of R21 and the value of X in Formula (31), it is possible to correspond to the degree of hydrophilicity or hydrophobicity of the pigment particle surface. As a preferable polymerizable surfactant represented by the formula (31), a compound represented by the following formula (310) can be exemplified. Specifically, in the following formulas (31a) to (31d) Mention may be made of the compounds represented.

A commercial item can also be used as said anionic polymerizable surfactant. For example, Aqualon HS series (Aqualon HS-05, HS-10, HS-20, HS-1025) from Daiichi Kogyo Seiyaku Co., Ltd. or Adeka Soap SE-10N, SE-20N from Asahi Denka Kogyo Co., Ltd. Can be mentioned.
Asahi Denka Kogyo Co., Ltd. Adekaria Soap SE-10N is a compound represented by the formula (310), in which M ¹ is NH ₄ , R 31 is C ₉ H ₁₉ , and m = 10. Adekaria Soap SE-20N manufactured by Asahi Denka Kogyo Co., Ltd. is a compound represented by formula (310) in which M ¹ is NH ₄ , R 31 is C ₉ H ₁₉ , and m = 20.
Examples of the anionic polymerizable surfactant used in the present invention include a general formula (33):

で表される化合物が好ましい。式（３３）で表される好ましいアニオン性重合性界面活性剤としては、以下の化合物を挙げることができる。

The compound represented by these is preferable. Preferred examples of the anionic polymerizable surfactant represented by the formula (33) include the following compounds.

A commercial item can also be used as said anionic polymerizable surfactant. For example, Aqualon KH series (Aqualon KH-5, Aqualon KH-10) from Daiichi Kogyo Seiyaku Co., Ltd. can be mentioned. Aqualon KH-5 is a mixture of a compound represented by the above formula wherein r is 9 and s is 5 and a compound where r is 11 and s is 5. Aqualon KH-10 is a mixture of a compound represented by the above formula wherein r is 9 and s is 10, and a compound where r is 11 and s is 10.
Moreover, as an anionic polymerizable surfactant, the compound represented by a following formula (A) is also preferable.

The anionic polymerizable surfactants exemplified above can be used alone or as a mixture of two or more.
The polymer layer 60 may have a repeating structural unit derived from an anionic polymerizable surfactant and a hydrophobic monomer, or may have a repeating structural unit derived from a crosslinkable monomer. May be. These will be described in detail later.

(2-3) Production of Microencapsulated Pigment The microencapsulated pigment described above is prepared by adding an anionic polymerizable surfactant to an aqueous dispersion of pigment particles having a cationic group on the surface and mixing them, and then anionic. It can manufacture suitably by adding a polymerization surfactant and emulsifying, and then adding a polymerization initiator and carrying out emulsion polymerization. In addition, since the pigment particles can be encapsulated even if the pigment particles are relatively small by using such a method, the microencapsulated pigment is compared with the size of the toner particles. Can be made sufficiently small. As a result, the colorant content among the toner particles can be made more uniform.

In the following, description will be made with reference to possible dispersion states of pigment particles in a preferred method for producing a microencapsulated pigment. However, the dispersion state of the pigment particles listed below includes estimation.
First, a possible dispersion state of pigment particles will be described with reference to FIG. The pigment particles 1 having a cationic group 14 as a hydrophilic group dispersed in a solvent containing water as a main component (hereinafter also referred to as an aqueous solvent) are mixed with an anionic group 11, a hydrophobic group 12, and a polymerizable group 13. The anionic group 11 of the anionic polymerizable surfactant 2 having the above is arranged so as to face the cationic group 14 of the pigment particle 1 and adsorbs with a strong ionic bond.

In this state, for example, by adding a polymerization initiator, the polymerizable groups 13 of the adjacent anionic polymerizable surfactant 2 are polymerized to form the pigment particles 1 in the polymer layer 60 as shown in FIG. A microencapsulated pigment 100 coated with is produced.
According to such an emulsion polymerization method, the arrangement form of the anionic polymerizable surfactant existing around the pigment particles before the polymerization reaction is very highly controlled. Then, the anionic polymerizable surfactant is converted into a polymer by the emulsion polymerization reaction while maintaining this highly controlled form. Therefore, the structure of the microencapsulated pigment is controlled with extremely high accuracy. That is, since the cationic group on the surface of the pigment particle and the anionic group of the anionic polymerizable surfactant are ionically bonded in the polymerization system to form a polymer phase by a polymerization reaction, emulsion polymerization is performed. The arrangement form of the monomers existing around the pigment particles in the front affects the polarization state of the surface of the particles after polymerization, and can therefore be controlled with extremely high accuracy.
More specifically, the microencapsulated pigment is preferably produced by the following procedure.

(1) First, an anionic polymerizable surfactant is added to a dispersion in which a pigment having a cationic group on its surface is dispersed in water. A part of the added anionic polymerizable surfactant is adsorbed on the cationic group of the “pigment having a cationic group on the surface” and is ionically bound to be immobilized.
Addition of the anionic polymerizable surfactant to the pigment having the cationic group on the surface when the anionic polymerizable surfactant is added to the aqueous dispersion of pigment particles having the cationic group on the surface The amount is 0 with respect to the total number of moles of the cationic group based on the amount of the pigment having a cationic group on the surface (= weight of the pigment used (g) × anionic group on the pigment surface (mol / g)). The range of 0.5 to 2 times mol is preferable, and the range of 0.8 to 1.2 times mol is more preferable. By setting the addition amount to 0.5 times mole or more, the pigment particles having a cationic group are strongly ionically bound and can be easily encapsulated. By setting the addition amount to 2 times or less, the generation of an anionic polymerizable surfactant not adsorbed on the pigment particles can be reduced.

(2) Next, a polymerization initiator is added and polymerized in water. Specifically, emulsion polymerization is performed.
As such a polymerization initiator, a water-soluble polymerization initiator is preferable, and potassium persulfate, ammonium persulfate, sodium persulfate, 2,2-azobis- (2-methylpropionamidine) dihydrochloride, or 4,4 -Azobis- (4-cyanovaleric acid) and the like.
The addition of the polymerization initiator can be suitably carried out by dropping an aqueous solution in which a water-soluble polymerization initiator is dissolved in pure water.

The polymerization initiator is preferably added in an activated state.
The activation of the polymerization initiator can be preferably carried out by raising the temperature of the aqueous dispersion to a predetermined polymerization temperature.
The polymerization reaction preferably uses a reaction vessel equipped with an ultrasonic generator, a stirrer, a reflux condenser, a dropping funnel and a temperature controller.

  After completion of the polymerization, it is preferable to adjust the pH within the range of 7.0 to 9.0 and perform filtration. Here, as described above, the aqueous solvent is a solvent containing water as a main component. In addition to water, the aqueous solvent includes, as an optional component, for example, a water-soluble solvent such as glycerin or glycol. May be. The polymerization temperature is preferably in the range of 60 ° C to 90 ° C. In addition, when the pigment particles having a cationic group as a hydrophilic group on the surface are not in the state of an aqueous dispersion, as a pretreatment, a dispersion treatment is performed using a general disperser such as a ball mill, a roll mill, an Eiger mill, or a jet mill. It is preferable to carry out.

In the microencapsulated pigment obtained as described above, pigment particles having a small average particle diameter are completely covered with a polymer layer (no defect portion).
By the above procedure, a microencapsulated pigment coated with a polymer having a repeating structural unit derived from an anionic polymerizable surfactant can be suitably produced.
Other comonomer may be added for the purpose of improving the fixing property of the toner particles and improving the storage stability of the microencapsulated pigment.

  In addition, an anionic polymerizable surfactant and a hydrophobic monomer may be present in the aqueous dispersion as necessary during the polymerization. In this case, the polymer layer has an anionic polymerizable surfactant. It becomes a copolymer layer copolymerized from the agent and the hydrophobic monomer. That is, the microencapsulated pigment has a repeating structure in which pigment particles having a cationic group are derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group, and a polymerizable group and a hydrophobic monomer. It is coated with a polymer (copolymer) having structural units.

  In such a microencapsulated pigment, the anionic polymerizable surfactant is added to an aqueous dispersion of pigment particles having a cationic group on the surface and mixed, and then a hydrophobic monomer and an anionic polymerizable surfactant are added. In addition, after emulsification, it can be suitably produced by adding a polymerization initiator and emulsion polymerization. Thereby, a more durable colorant can be manufactured. As a result, when the liquid developer is produced, unintentional peeling of the polymer covering the pigment can be effectively prevented. Moreover, the affinity with the resin is improved, and the dispersibility in the resin can be further increased.

  The hydrophobic monomer has at least a hydrophobic group and a polymerizable group in its structure, and the hydrophobic group is selected from the group consisting of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Can be illustrated. Examples of the aliphatic hydrocarbon group include a methyl group, an ethyl group, and a propyl group. Examples of the alicyclic hydrocarbon group include a cyclohexyl group, a dicyclopentenyl group, a dicyclopentanyl group, and an isobornyl group, and an aromatic hydrocarbon group. Examples thereof include a benzyl group, a phenyl group, and a naphthyl group.

The polymerizable group is an unsaturated hydrocarbon group capable of radical polymerization, and is preferably selected from the group consisting of a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group. .
Specific examples of the hydrophobic monomer include styrene and methylstyrene, dimethylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, p-chloromethylstyrene, divinylbenzene, and other styrene derivatives; methyl acrylate, ethyl acrylate, acrylic acid n-butyl, butoxyethyl acrylate, benzyl acrylate, phenyl acrylate, phenoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, tetrahydrofurfuryl acrylate, isobol Monofunctional acrylic esters such as nyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate Butoxymethyl methacrylate, benzyl methacrylate, phenyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, etc. Monofunctional methacrylate esters of allyl compounds such as allylbenzene, allyl-3-cyclohexanepropionate, 1-allyl-3,4-dimethoxybenzene, allylphenoxyacetate, allylphenylacetate, allylcyclohexane, allyl polycarboxylic acid allyl, etc. ; Ester cheeks of fumaric acid, maleic acid, itaconic acid; radically polymerizable groups such as N-substituted maleimides and cyclic olefins Monomer, and the like that. As the hydrophobic monomer, those satisfying the above-mentioned required characteristics are appropriately selected, and the addition amount thereof is arbitrarily determined.

  The amount of the hydrophobic monomer added is preferably in the range of about 5 to 900 parts by weight, more preferably in the range of 10 to 500 parts by weight, and particularly preferably in the range of 15 to 200 parts by weight with respect to 100 parts by weight of the pigment. It is a range. The amount of the anionic polymerizable surfactant that forms the outermost shell of the capsule is preferably in the range of about 0.5 to 5 times the mole of the anionic polymerizable surfactant added first, more preferably 1-2. The range is about a double mole. By setting it in the range of 1 mol or more, the dispersibility and dispersion stability of the encapsulated particles are excellent. Since the addition amount of 2 mol or less can suppress the generation of an anionic polymerizable surfactant that does not contribute to encapsulation, the generation of polymer particles in addition to the encapsulated particles can be prevented.

The polymer that coats the pigment particles also preferably has a repeating structural unit derived from a crosslinkable monomer.
By having a repeating structural unit derived from a crosslinkable monomer, a crosslinked structure is formed in the polymer, and the durability of the polymer can be improved.
Examples of the crosslinkable monomer include compounds having two or more unsaturated hydrocarbon groups selected from vinyl group, allyl group, acryloyl group, methacryloyl group, propenyl group, vinylidene group, and vinylene group. , Ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, allyl acrylate, bis (acryloxyethyl) hydroxyethyl isocyanurate, bis (acryloxy neopentyl glycol) adipate 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate Rate, polypropylene glycol diacrylate, 2-hydroxy-1,3-diaacryloxypropane, 2,2-bis [4- (acryloxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy) phenyl] propane 2,2-bis [4- (acryloxyethoxy diethoxy) phenyl] propane, 2,2-bis [4- (acryloxyethoxy polyethoxy) phenyl] propane, hydroxypentylglycol diacrylate, 1 , 4-butanediol diacrylate, dicyclopentanyl diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate , Tetrabromopisphenol A diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, tris (acryloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate Methacrylate, polyethylene glycol dimethacrylate, propylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate 2-hydroxy-1,3-dimethacryloxypropane, 2,2 -Bis [41- (methacryloxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxydiethoxy) phenyl] propane, 2, 2-bis [4- (methacryloxyethoxypolyethoxy) phenyl] propane, tetrabromobisphenol A dimethacrylate, dicyclopentanyl dimethacrylate, dipentaerythritol hexamethacrylate, glycerol dimethacrylate, hydroxypentylglycol dipentaglycol dimethacrylate Dipentaerythritol monohydroxypentamethacrylate, ditrimethylolpropane tetramethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, Rig Lise over roll dimethacrylate, trimethylolpropane trimethacrylate, tris (methacryloxyethyl) isocyanurate, allyl methacrylate, divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, diethylene glycol bis allyl carbonate.
Moreover, it is preferable that the polymer which coat | covers a pigment particle further has the repeating structural unit induced | guided | derived from the monomer represented by following General formula (1).

The R ² group, which is a “bulky” group derived from the monomer represented by the general formula (1) in the polymer, reduces the flexibility of the polymer molecule, that is, restricts the mobility of the molecule. The mechanical strength and heat resistance of the polymer are improved.
In the general formula (1), examples of the alicyclic hydrocarbon group represented by R ² include a cycloalkyl group, a cycloalkenyl group, a benzyl group, a phenyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, and an adamantane. Group, tetrahydrofuran group, naphthyl group, t-butyl group, and the like.

As described above, a polymer having a repeating structural unit derived from a crosslinkable monomer and a polymer having a repeating structural unit derived from the monomer represented by the general formula (1) have high Tg, mechanical strength, and heat resistance. There is an advantage that it is excellent in durability such as resistance and solvent resistance.
Moreover, the following are mentioned as a specific example of the monomer represented by the said General formula (1).

Further, the following hydrophilic monomers can be used together with the anionic polymerizable surfactant. As such a hydrophilic monomer, for example, a hydrophilic monomer having an anionic group as a hydrophilic group can be used. In this case, the polymer layer can be a copolymer layer copolymerized from an anionic polymerizable surfactant and / or a hydrophilic monomer having an anionic group and a comonomer.
Preferable specific examples of the hydrophilic monomer having an anionic group include, for example, methacrylic acid, acrylic acid, phosphoric acid group-containing (meth) acrylate, sodium vinyl sulfonate, 2-sulfoethyl methacrylate, 2-acrylamido-2-methyl. And propanesulfonic acid.

Moreover, you may use hydrophilic monomers other than the hydrophilic monomer which has an anionic group. Examples of the hydrophilic monomer other than the hydrophilic monomer having an anionic group include those having a hydroxyl group, an ethylene oxide group, an amide group, or an amino group as the hydrophilic group.
Specific examples of the hydrophilic monomer include 2-hydroxyethyl methacrylate having an OH group, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, and the like, ethyldiethylene glycol acrylate having an ethylene oxide group, polyethylene glycol monomethacrylate, Methoxypolyethylene glycol methacrylate, amide group-containing acrylamide, N, N-dimethylacrylamide, etc., amino group-containing N-methylaminoethyl methacrylate, N-methylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl Alkylamines of acrylic acid or methacrylic acid such as methacrylate and diethylaminoethyl methacrylate Esters: N- (2-dimethylaminoethyl) acrylamide, N- (2-dimethylaminoethyl) methacrylamide, N, N-dimethylaminopropylacrylamide, and other unsaturated amides having an alkylamino group, and vinyl Examples thereof include monovinyl pyridines such as pyridine, vinyl ethers having an alkylamino group such as dimethylaminoethyl vinyl ether; vinyl imidazole, N-vinyl-2-pyrrolidone and the like.

  The microencapsulated pigment is produced by adding the anionic polymerizable surfactant to an aqueous dispersion of pigment particles having a cationic group as a hydrophilic group on the surface, and water or water and aqueous as necessary. After adding a solvent and mixing and irradiating ultrasonic waves for a predetermined time, the anionic polymerizable surfactant and / or the hydrophilic monomer (in addition to the above-mentioned hydrophobic monomer, crosslinkable monomer, general formula (1 The monomer represented by) can also be added.) If necessary, water is added and dispersed again by irradiating with ultrasonic waves for a predetermined time, and at a predetermined temperature (polymerization initiator) while performing ultrasonic irradiation and stirring. The temperature can be suitably increased by adding the polymerization initiator to activate the polymerization initiator and emulsion polymerization.

  When the hydrophobic monomer is used, more specifically, an anionic polymerizable property having an anionic group, a hydrophobic group, and a polymerizable group in an aqueous dispersion of pigment particles having the cationic group on the surface. An anionic polymerizable surfactant having an anionic group, a hydrophobic group, and a polymerizable group, a step of adding and mixing a surfactant and irradiating with ultrasonic waves, a step of adding and mixing a hydrophobic monomer, and an anionic group, a hydrophobic group and a polymerizable group It comprises a step of adding and mixing an agent and / or a hydrophilic monomer and irradiating with ultrasonic waves, and a step of emulsion polymerization by adding a polymerization initiator, and it is more preferably produced by carrying out in the order of the steps described above. Can do.

  In the case of using the crosslinkable monomer and / or the monomer represented by the general formula (1), more specifically, an anionic group is added to the aqueous dispersion of pigment particles having the cationic group on the surface. And a step of adding an anionic polymerizable surfactant having a hydrophobic group and a polymerizable group, mixing and irradiating with ultrasonic waves, a crosslinkable monomer and / or the general formula (1) A step of adding and mixing the monomer, a step of adding and mixing the anionic polymerizable surfactant and / or the hydrophilic monomer and irradiating with ultrasonic waves, and a step of emulsion polymerization by adding a polymerization initiator It can comprise more suitably by implementing in order of the said process.

  Further, when the crosslinkable monomer and / or the monomer represented by the general formula (1) is used, more specifically, an anionic group is added to the aqueous dispersion of pigment particles having the cationic group on the surface. And a step of adding an anionic polymerizable surfactant having a hydrophobic group and a polymerizable group, mixing and irradiating with ultrasonic waves, a crosslinkable monomer and / or the general formula (1) A step of adding and mixing a monomer and a monomer having a long-chain alkyl group, a step of adding and mixing an anionic polymerizable surfactant and / or the hydrophilic monomer and irradiating with ultrasonic waves, and a polymerization initiator It can be more suitably manufactured by carrying out the emulsion polymerization step and adding the step.

As described above, first, an anionic polymerizable surfactant is adsorbed to the cationic group on the surface of the pigment particle having a cationic group on the surface, and then a hydrophobic monomer is added, and then the anionic polymerizable surfactant and / or Alternatively, by adding a hydrophilic monomer and irradiating with ultrasonic waves, the arrangement of the polymerizable surfactant and monomer present around the pigment particles is extremely highly controlled. Then, by emulsion polymerization, the monomer is converted into a polymer in this highly controlled form, and the microencapsulated pigment according to this embodiment is obtained. Thereby, the production | generation of the water-soluble oligomer and polymer which are a by-product can be reduced.
In the microencapsulated pigment obtained as described above, pigment particles having a small average particle diameter are completely covered with a polymer layer (no defect portion).

Next, another dispersion state in which pigment particles can occur in the preferred method for producing a microencapsulated pigment described above will be described with reference to FIG. The anionic group 11 of the anionic polymerizable surfactant 2 having an anionic group 11, a hydrophobic group 12 and a polymerizable group 13 is added to the pigment particle 1 having a cationic group 14 on the surface as a hydrophilic group. It arrange | positions so that it may face 1 cationic group 14, and it adsorb | sucks by a strong ionic bond. Further, the surface of the pigment particle 1 has a cationic group 14 chemically bonded at a specific density, and has a hydrophobic region between the cationic groups 14, and an anionic polymerizable surfactant in the hydrophobic region. The anionic group of another anionic polymerizable surfactant 2 is arranged on the anionic group 11 of the anionic polymerizable surfactant 2. .
In this state, for example, a polymerization initiator is added to polymerize the polymerizable groups 13 of the adjacent anionic polymerizable surfactants 2, whereby the pigment particles 1 become polymer layers 60 as shown in FIG. A microencapsulated pigment 101 coated with 'is produced.

3. Other Components The toner may contain components other than those described above. Examples of such components include waxes, charge control agents, magnetic powders, and the like.
Examples of the wax include hydrocarbon waxes such as ozokerite, cercin, paraffin wax, microwax, microcrystalline wax, petrolatum, Fischer-Tropsch wax, carnauba wax, rice wax, methyl laurate, methyl myristate, palmitic acid. Methyl, methyl stearate, butyl stearate, candelilla wax, cotton wax, wood wax, beeswax, lanolin, montan wax, fatty acid ester ester wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax Olefin waxes such as 12-hydroxy stearamide, stearamide, phthalic anhydride amide wax, Lauro , Ketone waxes such as stearone, ether waxes, and the like, can be used singly or in combination of two or more of them.

Examples of the charge control agent include benzoic acid metal salts, salicylic acid metal salts, alkylsalicylic acid metal salts, stearic acid metal salts, catechol metal salts, metal-containing bisazo dyes, nigrosine dyes, tetraphenylborate derivatives, fourth Examples include quaternary ammonium salts, alkylpyridinium salts, chlorinated polyesters, and nitrofunnic acid.
Examples of the magnetic powder include magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, magnesium oxide, and other metal oxides, and magnetic materials such as Fe, Co, and Ni. The thing etc. which were comprised with the magnetic material containing a metal are mentioned.

In addition to the above materials, the toner may contain, for example, zinc stearate, zinc oxide, cerium oxide, silica, titanium oxide, iron oxide, fatty acid, fatty acid metal salt, and the like.
The other components described above may be contained in the liquid developer. For example, the other components may be contained in the toner particles or in the insulating liquid.

<Method for producing liquid developer>
Next, a preferred embodiment of the method for producing a liquid developer of the present invention will be described.
The method for producing a liquid developer according to the present invention includes a step of preparing a dispersion in which a dispersoid containing the toner constituent material as described above is dispersed in a dispersion medium, and spraying the dispersion as droplets to disperse the dispersion. A dispersion medium removing step of removing the medium to obtain dry fine particles, and a dispersion step of dispersing the dry fine particles in the insulating liquid.

In this embodiment, a case where an aqueous dispersion in which a dispersoid is dispersed in an aqueous dispersion medium composed of an aqueous liquid is used as the dispersion. By using an aqueous dispersion, a liquid developer can be provided in an environmentally friendly manner.
The aqueous dispersion may be prepared by any method, but in this embodiment, the aqueous dispersion is prepared using a kneaded material containing the colorant and the resin material as described above.
As a constituent material (component) of the kneaded material, in addition to the material constituting the toner as described above, for example, a material used as a solvent such as an inorganic solvent or an organic solvent may be used. Thereby, for example, the efficiency of kneading can be improved, and a kneaded product in which the components are more uniformly mixed can be easily obtained.

[Kneading process]
Hereinafter, the adjustment method of a kneaded material is demonstrated.
Since the colorant (microencapsulated pigment) used in the present invention has a high affinity with the resin material and a high dispersibility in the resin, it can be easily and uniformly dispersed in the kneaded product. Therefore, the liquid developer produced using the kneaded product has a small variation in characteristics among the toner particles.

The kneaded material K7 can be manufactured using, for example, an apparatus as shown in FIG.
The raw material K5 used for kneading contains the components as described above. In particular, in a composition containing a colorant, since the colorant easily embeds air, air tends to remain in the composition. However, by kneading in this step, In particular, air entrained by the colorant can be efficiently removed, and bubbles can be effectively prevented from being mixed (remaining) inside the toner particles.
The raw material K5 used for kneading is preferably a mixture of these components.

This embodiment demonstrates the structure which uses a biaxial kneading extruder as a kneading machine.
The kneading machine K1 includes a process part K2 for kneading while conveying the raw material K5, a head part K3 for extruding the kneaded raw material (kneaded material K7) into a predetermined cross-sectional shape, and a raw material K5 in the process part K2. And a feeder K4 to be supplied.
The process part K2 includes a barrel K21, a screw K22 and a screw K23 inserted into the barrel K21, and a fixing member K24 for fixing the head part K3 to the tip of the barrel K21.
In the process part K2, when the screw K22 and the screw K23 rotate, a shearing force is applied to the raw material K5 supplied from the feeder K4, and a uniform kneaded material K7 is obtained.

  The total length of the process part K2 is preferably 50 to 300 cm, and more preferably 100 to 250 cm. If the total length of the process part K2 is less than the lower limit, it may be difficult to mix the components in the raw material K5 sufficiently uniformly. On the other hand, when the total length of the process part K2 exceeds the upper limit, depending on the temperature in the process part K2, the number of rotations of the screw K22, the screw K23, and the like, the material K5 is easily denatured by heat, and finally obtained. It may be difficult to sufficiently control the physical properties of the liquid developer (toner).

  Moreover, although the raw material temperature at the time of kneading | mixes changes with compositions etc. of the raw material K5, it is preferable that it is 80-260 degreeC, and it is more preferable that it is 90-230 degreeC. Note that the raw material temperature in the process part K2 may be uniform or may vary depending on the part. For example, the process unit K2 includes a first region having a relatively low set temperature and a second region that is provided on the base end side from the first region and whose set temperature is higher than the first region. You may have.

  In addition, the residence time (time required for passage) of the raw material K5 in the process part K2 is preferably 0.5 to 12 minutes, and more preferably 1 to 7 minutes. If the residence time in the process part K2 is less than the lower limit, it may be difficult to mix the components in the raw material K5 sufficiently uniformly. On the other hand, if the residence time in the process part K2 exceeds the upper limit, the production efficiency is reduced. Depending on the temperature in the process part K2, the rotational speed of the screw K22, the screw K23, etc., the heat of the raw material K5 Modification is likely to occur, and it may be difficult to sufficiently control the physical properties of the finally obtained liquid developer (toner).

  The number of rotations of the screw K22 and the screw K23 varies depending on the composition of the binder resin and the like, but is preferably 50 to 600 rpm. If the rotational speeds of the screws K22 and K23 are less than the lower limit, it may be difficult to mix the components in the raw material K5 sufficiently uniformly. On the other hand, when the rotation speed of the screw K22 and the screw K23 exceeds the upper limit value, the molecular chain of the resin may be cut by shearing, and the resin characteristics may be deteriorated.

  Further, in the kneader K1 used in the present embodiment, the inside of the process unit K2 is connected to the pump P via the deaeration port K25. Thereby, the inside of the process part K2 can be degassed, and an increase in the pressure in the process part K2 due to heating or heat generation of the raw material K5 (kneaded material K7) can be prevented. As a result, the kneading process can be performed safely and efficiently. Further, since the inside of the process part K2 is connected to the pump P via the deaeration port K25, it is possible to effectively prevent bubbles (particularly relatively large bubbles) from being contained in the obtained kneaded material K7. And the properties of the liquid developer (toner) finally obtained can be made more excellent.

[Extrusion process]
The kneaded material K7 kneaded in the process part K2 is pushed out of the kneader K1 through the head part K3 by the rotation of the screw K22 and the screw K23.
The head part K3 has an internal space K31 into which the kneaded material K7 is fed from the process part K2, and an extrusion port K32 from which the kneaded material K7 is extruded.

The temperature of the kneaded material K7 in the internal space K31 (at least in the vicinity of the extrusion port K32) is not particularly limited, but is preferably a temperature equal to or higher than the softening temperature of the resin material contained in the raw material K5. As a result, the toner particles can be obtained as a mixture of the constituent components more uniformly, and variations in characteristics (charging characteristics, fixing properties, etc.) among the toner particles can be particularly reduced.
The specific temperature of the kneaded material K7 in the internal space K31 (at least the temperature near the extrusion port K32) is not particularly limited, but is preferably 80 to 150 ° C, more preferably 90 to 140 ° C. preferable. When the temperature of the kneaded material K7 in the internal space K31 is a value within the above range, the kneaded material K7 does not solidify in the internal space K31 and is easily extruded from the extrusion port K32.

  In the illustrated configuration, the internal space K31 has a cross-sectional area gradually decreasing portion K33 in which the cross-sectional area gradually decreases in the direction of the extrusion port K32. By having such a cross-sectional area gradually decreasing portion K33, the extrusion amount of the kneaded material K7 extruded from the extrusion port K32 is stabilized, and the cooling rate of the kneaded material K7 in the cooling step described later is stabilized. As a result, the toner produced using the toner has a small variation in characteristics among the toner particles, and has excellent overall characteristics.

[Cooling process]
The softened kneaded material K7 extruded from the extrusion port K32 of the head portion K3 is cooled and solidified by the cooler K6.
The cooler K6 includes rolls K61, K62, K63, and K64, and belts K65 and K66.

The belt K65 is wound around a roll K61 and a roll K62. Similarly, the belt K66 is wound around the roll K63 and the roll K64.
The rolls K61, K62, K63, and K64 rotate around the rotation axes K611, K621, K631, and K641 in the directions indicated by e, f, g, and h in the drawing. Thereby, the kneaded material K7 extruded from the extrusion port K32 of the kneading machine K1 is introduced between the belt K65 and the belt K66. The kneaded material K7 introduced between the belt K65 and the belt K66 is cooled while being formed into a plate shape having a substantially uniform thickness. The cooled kneaded material K7 is discharged from the discharge portion K67. The belts K65 and K66 are cooled by a method such as water cooling or air cooling. When such a belt type is used as the cooler, the contact time between the kneaded product extruded from the kneader and the cooling body (belt) can be increased, and the cooling efficiency of the kneaded product is particularly excellent. Can be.

  By the way, in the kneading process, since shearing force is applied to the raw material K5, phase separation (particularly macrophase separation) is sufficiently prevented, but the kneaded product K7 that has finished the kneading process is not subjected to shearing force. Therefore, depending on the constituent materials of the kneaded product, phase separation (macrophase separation) or the like may occur again if left for a long period of time. Therefore, it is preferable to cool the kneaded material K7 obtained as described above as soon as possible. Specifically, the cooling rate of the kneaded material K7 (for example, the cooling rate when the kneaded material K7 is cooled to about 60 ° C.) is preferably 3 ° C./second or more, and is preferably 5-100 ° C./second. Is more preferable. Further, the time required from the end of the kneading step (when the shearing force is no longer applied) to the completion of the cooling step (for example, the time required for cooling the temperature of the kneaded product K7 to 60 ° C. or lower) is 20 seconds. Or less, more preferably 3 to 12 seconds.

In the present embodiment, the configuration using a continuous biaxial kneading extruder as the kneading machine has been described, but the kneading machine used for kneading the raw materials is not limited to this. For kneading the raw materials, for example, various kneaders such as a kneader, a batch type triaxial roll, a continuous biaxial roll, a wheel mixer, and a blade type mixer can be used.
In the illustrated configuration, a kneader having two screws has been described. However, the number of screws may be one or three or more. Further, the kneading apparatus may have a disc (kneading disc) portion.

Further, in the present embodiment, the configuration using one kneader has been described, but kneading may be performed using two kneaders. In this case, the heating temperature of the raw material, the rotational speed of the screw, and the like may be different between one kneader and the other kneader.
In the present embodiment, a configuration using a belt type as the cooler has been described. However, for example, a roll type (cooling roll type) cooler may be used. Further, the cooling of the kneaded product extruded from the extrusion port K32 of the kneader is not limited to the one using the above-described cooler, and may be performed by, for example, air cooling.

[Crushing process]
Next, the kneaded material K7 that has undergone the cooling process as described above is pulverized. Thus, by pulverizing the kneaded material K7, an aqueous dispersion (aqueous emulsion or aqueous suspension) described later can be obtained as a dispersion of finer dispersoids relatively easily. As a result, the liquid developer finally obtained can also have a smaller toner particle size and can be suitably used for high-resolution image formation.

The pulverization method is not particularly limited, and can be performed using various pulverizers and crushers such as a ball mill, a vibration mill, a jet mill, and a pin mill.
The pulverization process may be performed in multiple steps (for example, two stages of a coarse pulverization process and a fine pulverization process). In addition, after such a pulverization step, a classification process or the like may be performed as necessary. For the classification treatment, for example, a sieve, an airflow classifier or the like can be used.

  By kneading the raw material K5 as described above, the air contained in the raw material K5 can be effectively removed. In other words, the kneaded material K7 obtained by kneading as described above contains almost no air (bubbles) inside. Thereby, it is possible to effectively prevent the generation of irregularly shaped particles (hollow particles, missing particles, fused particles, etc.) in the aqueous dispersion spraying step described later. As a result, in the finally obtained liquid developer, it is possible to effectively prevent problems such as a decrease in transferability and cleaning property due to irregularly shaped toner particles.

In this embodiment, an aqueous dispersion is prepared using the kneaded material as described above. In particular, in this embodiment, an aqueous emulsion is once prepared using the kneaded material as described above, and then an aqueous suspension is prepared using the aqueous emulsion.
By using the kneaded material K7 for the preparation of the aqueous dispersion (aqueous emulsion), the following effects can be obtained. That is, even when the toner constituent materials contain components that are difficult to disperse or compatible with each other, each component is sufficiently compatible and finely dispersed in the resulting kneaded product by kneading. State. In particular, pigments (coloring agents) usually have low dispersibility in liquids used as solvents as described later, but are kneaded in advance before being dispersed in the solvent, so that resin particles and the like are surrounded by pigment particles. Thus, the dispersibility of the pigment in the solvent is improved (particularly fine dispersion in the solvent is possible), and the color development property of the finally obtained toner is also improved. For this reason, a component (hereinafter referred to as “hardly dispersible component”) having poor dispersibility with respect to the dispersion medium (aqueous dispersion medium) of the aqueous dispersion liquid (aqueous emulsion liquid, aqueous suspension) described later in the constituent material of the toner. ) And components that are poorly soluble in the solvent contained in the dispersion medium of the aqueous emulsion (hereinafter also referred to as “hardly soluble components”). In particular, the dispersibility of the dispersoid in the aqueous suspension) can be made particularly excellent. As a result, even in the finally obtained liquid developer, variations in composition and characteristics among the toner particles are reduced, and the overall characteristics are particularly excellent.

<Aqueous emulsion preparation process>
Next, using the kneaded material K7 as described above, an aqueous emulsion in which the dispersoid composed of the toner material is dispersed in the aqueous dispersion medium composed of the aqueous liquid is prepared (aqueous emulsion preparation step). .
In an aqueous emulsion, the dispersoid is liquid (has fluidity and can be deformed relatively easily), so the dispersoid has a shape with a large degree of circularity (sphericity) due to its surface tension. Show the trend. Therefore, the suspension (aqueous suspension) prepared using the aqueous emulsion also has a relatively high circularity (sphericity) in the shape of the dispersoid. The circularity (sphericity) is relatively large. In addition, in the case of an emulsion in which the dispersoid is liquid (has fluidity and can be deformed relatively easily), the uniformity of the size of the dispersoid can be relatively easily achieved by, for example, stirring the emulsion. It can be high enough.

  The method for preparing the aqueous emulsion is not particularly limited. In this embodiment, a solution of the kneaded product K7 in which at least a part of the kneaded product K7 is dissolved is obtained, and the aqueous emulsion is dispersed by dispersing the solution in the aqueous liquid. Prepare. In the present specification, “emulsion (emulsion, emulsion, emulsion)” refers to a dispersion in which a liquid dispersoid (dispersed particles) is dispersed in a liquid dispersion medium, “Suspension” refers to a dispersion (including suspension colloid) in which a solid (solid) dispersoid (suspension particles) is dispersed in a liquid dispersion medium. Further, when the liquid dispersoid and the solid dispersoid coexist in the dispersion, the total volume of the liquid dispersoid in the dispersion is larger than the total volume of the solid dispersoid. The larger one is used as an emulsified liquid, and in the dispersion liquid, the total volume of the solid dispersoid is larger than the total volume of the liquid dispersoid.

Hereinafter, a method for preparing the aqueous emulsion will be described in detail.
[Preparation of kneaded product solution (solution of kneaded product)]
In this embodiment, first, a kneaded product solution in which at least a part of the kneaded product is dissolved is obtained.
The solution can be prepared by mixing the kneaded product and a solvent capable of dissolving at least a part of the kneaded product.
The solvent used for the preparation of the solution may be any solvent as long as it can dissolve at least a part of the kneaded product, but is usually used with an aqueous liquid described later (an aqueous liquid used for preparing an aqueous emulsion). Those having low compatibility (for example, a liquid having a solubility of 10 g or less in 100 g of an aqueous liquid at 25 ° C.) are used.

  Examples of such solvents include inorganic solvents such as carbon disulfide and carbon tetrachloride, ketone solvents such as methyl ethyl ketone (MEK), methyl isopropyl ketone (MIPK), and 2-heptanone, pentanol, n-hexanol, Alcohol solvents such as 1-octanol and 2-octanol, ether solvents such as diethyl ether and anisole, aliphatic hydrocarbon solvents such as hexane, pentane, heptane, cyclohexane, octane and isoprene, toluene, xylene, benzene and ethylbenzene , Aromatic hydrocarbon solvents such as naphthalene, aromatic heterocyclic compound solvents such as furan and thiophene, halogen compound solvents such as chloroform, ester solvents such as ethyl acetate, isopropyl acetate, isobutyl acetate, ethyl acrylate, Acrylonitrile, etc. Nitrile solvents, nitromethane an organic solvent such as nitro-based solvents such as nitroethane and the like, can be used a mixture of one or two or more selected from these.

Although the content rate of the solvent in a solution is not specifically limited, It is preferable that it is 5-75 wt%, It is more preferable that it is 10-70 wt%, It is further more preferable that it is 15-65 wt%. If the solvent content is less than the lower limit, depending on the solubility (solubility) of the kneaded product in the solvent, it may be difficult to sufficiently dissolve the kneaded product. On the other hand, when the content of the solvent exceeds the upper limit, the time required for removing the solvent in the subsequent processing becomes longer, and the productivity of the liquid developer is lowered. In addition, if the content of the solvent is too high, components that are sufficiently uniformly mixed may be phase-separated in the above-described kneading step, whereby each toner in the finally obtained liquid developer. It may be difficult to sufficiently reduce the variation in particle characteristics.
In the solution, it is sufficient that at least a part of the components constituting the kneaded material is dissolved (including swelling), and insoluble matter that is not dissolved may exist in the solution.

[Preparation of aqueous emulsion]
Next, an aqueous emulsion is obtained by mixing the above solution with an aqueous liquid. In this aqueous emulsion, the dispersoid containing the solvent and the constituent material of the kneaded material is usually dispersed in an aqueous dispersion medium composed of the aqueous liquid.
In the present invention, the “aqueous liquid” refers to a liquid containing at least water (H ₂ O), and is preferably composed mainly of water. The content of water in the aqueous liquid is preferably 50 wt% or more, preferably 80 wt% or more, and preferably 90 wt% or more. The aqueous liquid may contain components other than water. For example, the aqueous liquid may include a component having excellent compatibility with water (for example, a substance having a solubility in 100 g of water at 25 ° C. of 30 g or more). Examples of such components include alcohol solvents such as methanol, ethanol and propanol, ether solvents such as 1,4-dioxane and tetrahydrofuran (THF), and aromatic heterocyclic compound solvents such as pyridine, pyrazine and pyrrole. Amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, and aldehyde solvents such as acetaldehyde.

  Further, for the preparation of the aqueous emulsion (aqueous dispersion), for example, a dispersant may be used for the purpose of improving the dispersibility of the dispersoid. Examples of the dispersant include inorganic dispersants such as tricalcium phosphate, nonionic organic dispersants such as polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol, metal tristearate (for example, aluminum salt), and metal distearate. Salt (eg, aluminum salt, barium salt, etc.), stearic acid metal salt (eg, calcium salt, lead salt, zinc salt, etc.), linolenic acid metal salt (eg, cobalt salt, manganese salt, lead salt, zinc salt, etc.) , Octanoic acid metal salts (for example, aluminum salts, calcium salts, cobalt salts, etc.), oleic acid metal salts (for example, calcium salts, cobalt salts, etc.), palmitic acid metal salts (for example, zinc salts, etc.), dodecylbenzenesulfonic acid Metal salts (for example, sodium salts), naphthenic acid metal salts (for example, calcium salts, Baltic salts, manganese salts, lead salts, zinc salts, etc.), resinate metal salts (eg calcium salts, cobalt salts, manganese lead salts, zinc salts etc.), polyacrylic acid metal salts (eg sodium salts), poly Methacrylic acid metal salt (for example, sodium salt), polymaleic acid metal salt (for example, sodium salt), acrylic acid-maleic acid copolymer metal salt (for example, sodium salt), polystyrene sulfonic acid metal salt (for example, Anionic organic dispersants such as sodium salts) and cationic organic dispersants such as quaternary ammonium salts (such as dodecyltrimethylammonium chloride). By using the dispersant as described above for the preparation of the aqueous emulsion, the dispersibility of the dispersoid is improved and the dispersion of the shape and size of the dispersoid in the aqueous emulsion is relatively small. In addition, the shape of the dispersoid can be substantially spherical. As a result, the final liquid developer can be obtained in a substantially spherical shape and composed of toner particles having a uniform shape and size. Moreover, the storage stability of an aqueous emulsion can be made especially excellent by using the above dispersing agents for preparation of an aqueous emulsion.

The mixing of the solution and the aqueous liquid is preferably performed while stirring at least one of the liquids. Thereby, an emulsion (aqueous emulsion) in which a dispersoid having a small variation in size and shape is uniformly dispersed can be easily and reliably obtained.
As a specific method of mixing the solution and the aqueous liquid, for example, a method of adding the solution to the aqueous liquid in the container (for example, a method of dropping), a method of adding the aqueous liquid to the solution in the container (for example, And the like). In these cases, it is preferable to add at least the other liquid to the stirred liquid. Thereby, the effect mentioned above is exhibited more notably.

The content of the dispersoid in the aqueous emulsion is not particularly limited, but is preferably 5 to 55 wt%, and more preferably 10 to 50 wt%. Thereby, the productivity of toner particles (liquid developer) can be made particularly excellent while preventing unintentional bonding (aggregation) between dispersoids in the aqueous emulsion more reliably.
The average particle size of the dispersoid in the aqueous emulsion is not particularly limited, but is preferably 0.01 to 1.0 μm, and more preferably 0.05 to 0.5 μm. As a result, unintentional bonding (aggregation) between the dispersoids in the aqueous emulsion can be more reliably prevented, and the size of the toner particles finally obtained can be optimized. In the present specification, “average particle diameter” refers to an average particle diameter based on volume.
In the above description, the components in the kneaded product are described as being included in the dispersoid in the aqueous emulsion, but some of the components of the kneaded product may be included in the dispersion medium.
Moreover, components other than the above may be contained in the aqueous emulsion. Examples of such components include a charge control agent and magnetic powder.

Examples of the charge control agent include a metal salt of benzoic acid, a metal salt of salicylic acid, a metal salt of alkyl salicylic acid, a metal salt of catechol, a metal-containing bisazo dye, a nigrosine dye, a tetraphenylborate derivative, a quaternary ammonium salt, Examples thereof include alkyl pyridinium salts, chlorinated polyesters, and nitrohumic acid.
Examples of the magnetic powder include magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, magnesium oxide, and other metal oxides such as Fe, Co, and Ni. The thing comprised with the magnetic material containing a magnetic metal etc. are mentioned.
In addition to the above materials, for example, zinc stearate, zinc oxide, cerium oxide or the like may be added to the aqueous emulsion.

<Aqueous suspension preparation process>
The aqueous emulsion obtained as described above may be used as it is as a spray liquid for producing toner particles, but in this embodiment, an aqueous system (a liquid dispersoid dispersed in an aqueous dispersion medium) is used. An aqueous suspension 3 in which a solid dispersoid 31 is dispersed in a dispersion medium (aqueous dispersion medium) 32 is obtained from the emulsion, and the aqueous suspension 3 is used as a spray liquid for producing toner particles. As a result, inadvertent aggregation between the dispersoids and between the toner particles can be prevented more effectively, and as a result, the uniformity of the shape and size of the toner particles can be made particularly excellent. . Further, deaeration treatment can be performed along with the removal of the solvent, and the formation of irregularly shaped toner particles can be more effectively prevented. Further, along with the removal of the solvent, the aqueous dispersion medium (water) can efficiently penetrate (substitute) into the dispersoid, and as a result, the final toner particles can be obtained with an appropriate water content. .

Hereinafter, a method for preparing the aqueous suspension 3 will be described in detail.
The aqueous suspension 3 can be prepared by removing the solvent constituting the dispersoid from the aqueous emulsion.
The solvent can be removed by, for example, heating (heating) the aqueous emulsion or placing it in a reduced-pressure atmosphere, but it is preferable to remove the solvent by heating the aqueous emulsion under reduced pressure. . Thereby, the aqueous suspension 3 in which the dispersion of the size and shape of the dispersoid 31 is particularly small can be obtained relatively easily. Further, by removing the solvent as described above, deaeration treatment can be performed along with the removal of the solvent. Thereby, the dissolved amount of the gas in the aqueous suspension 3 can be reduced, and the dispersion medium 32 is removed from the droplet 5 of the aqueous suspension 3 in the dispersion medium removing unit M3 of the liquid developer manufacturing apparatus M1. In doing so, it is possible to effectively prevent bubbles and the like from being generated in the aqueous suspension 3. As a result, it is possible to more effectively prevent the irregularly shaped toner particles (hollow particles, missing particles, etc.) from being mixed into the finally obtained liquid developer.

When the aqueous emulsion is heated (warmed), the heating temperature is preferably 30 to 110 ° C, more preferably 40 to 100 ° C. When the heating temperature is a value within the above range, the generation of the irregularly shaped dispersoid 31 is sufficiently prevented (the solvent is surely prevented from evaporating (boiling) from the dispersoid of the aqueous emulsion). However, the solvent can be removed quickly.
Further, when the aqueous emulsion is placed in a reduced pressure atmosphere, the pressure of the atmosphere in which the aqueous emulsion is placed is preferably 0.1 to 50 kPa, and more preferably 0.5 to 5 kPa. When the pressure of the atmosphere in which the aqueous emulsion is placed is a value within the above range, the generation of the irregularly shaped dispersoid 31 is sufficiently prevented (the solvent is rapidly vaporized (boiling from the inside of the dispersoid of the aqueous emulsion). The solvent can be removed quickly, while reliably preventing).
The removal of the solvent may be performed so long as the dispersoid is in a solid state, and may not remove substantially all of the solvent contained in the aqueous emulsion.
The average particle size of the dispersoid 31 in the aqueous suspension 3 is not particularly limited, but is preferably 0.01 to 1.0 μm, and more preferably 0.05 to 0.5 μm. Thereby, the unintentional coupling | bonding (aggregation) of dispersoids can be prevented more reliably.

<Aqueous dispersion medium removal step (dispersion medium removal step)>
Next, dry fine particles corresponding to the dispersoid of the aqueous dispersion (aqueous suspension 3) are obtained by removing the aqueous dispersion medium from the aqueous dispersion (aqueous suspension 3) (aqueous dispersion medium removal step). . The dry fine particles thus obtained correspond to the toner particles of the liquid developer.
In the present invention, droplets are formed by spraying the dispersion, and the aqueous dispersion medium is removed from the droplets to obtain dry fine particles.

  The spraying of the dispersion liquid (aqueous suspension) may be performed by any method, but it is preferable to intermittently discharge droplets of the aqueous suspension. As a result, the aqueous dispersion medium can be removed more efficiently while effectively preventing unintentional aggregation of the dispersoid, and the productivity of the liquid developer is improved. In addition, even when a part of the solvent remains in the preparation of the aqueous suspension described above, the aqueous dispersion medium is removed by intermittently discharging droplets of the aqueous suspension to remove the aqueous dispersion medium. The remaining solvent can be efficiently removed together with the aqueous dispersion medium.

In particular, in the present embodiment, the aqueous dispersion medium is removed using a liquid developer manufacturing apparatus as shown in FIGS.
As shown in FIG. 6, the dry fine particle manufacturing apparatus (toner particle manufacturing apparatus) M1 includes a head unit M2 that intermittently discharges the aqueous suspension (aqueous dispersion) 3 as droplets 9 as described above, An aqueous suspension supply unit (aqueous dispersion supply unit) M4 that supplies the aqueous suspension 3 to the head unit M2, and a droplet-shaped (particulate) aqueous suspension 3 (liquid) discharged from the head unit M2. A dispersion medium removing unit M3 that removes the dispersion medium 32 while transporting the droplets 9) to form dry fine particles (toner particles) 4, and a recovery unit M5 that collects the produced dry fine particles (toner particles) 4. ing.

  The aqueous suspension supply unit M4 may have any function as long as it has a function of supplying the aqueous suspension 3 to the head unit M2, but in this embodiment, as shown in FIG. Means M41 is provided. Thereby, for example, even if the dispersoid 31 is difficult to disperse in the dispersion medium (aqueous dispersion medium) 32, the aqueous suspension 3 in which the dispersoid 31 is sufficiently uniformly dispersed is transferred to the head portion M2. Can be supplied.

The head part M2 has a function of discharging the aqueous suspension 3 as fine droplets (fine particles) 9.
The head unit M2 includes a dispersion liquid storage unit M21, a piezoelectric element M22, and a discharge unit M23.
The aqueous suspension 3 is stored in the dispersion liquid storage unit M21.
The aqueous suspension 3 stored in the dispersion liquid storage unit M21 is discharged as a droplet 9 from the discharge unit M23 forming the nozzle to the dispersion medium removal unit M3 by the pressure pulse (piezoelectric pulse) of the piezoelectric element M22. .

The shape of the discharge portion M23 (nozzle discharge port) is not particularly limited, but is preferably substantially circular. As a result, the sphericity of the discharged aqueous suspension 3 and the dry fine particles 4 formed in the dispersion medium removing unit M3 can be increased.
When the discharge part M23 has a substantially circular shape, the diameter (nozzle diameter) is preferably, for example, 5 to 500 μm, and more preferably 10 to 200 μm. If the diameter of the ejection part M23 is less than the lower limit, clogging is likely to occur, and the variation in the size of the ejected droplets 9 may increase. On the other hand, when the diameter of the discharge part M23 exceeds the upper limit, depending on the force relationship between the negative pressure of the dispersion liquid storage part M21 and the surface tension of the nozzle, the discharged aqueous suspension 3 (droplet 9) There is a possibility of embracing bubbles.

Further, the vicinity of the discharge portion M23 of the head portion M2 (particularly, the inner surface of the opening of the discharge portion M23 and the surface on the side where the discharge portion M23 of the head portion M2 is provided (the lower surface in the drawing)) The turbid liquid 3 preferably has liquid repellency (water repellency). Thereby, it can prevent effectively that the aqueous suspension 3 adheres to discharge part vicinity. As a result, it is possible to effectively prevent a so-called poor liquid runout or a discharge failure of the aqueous suspension 3. In addition, since the aqueous suspension 3 is effectively prevented from adhering to the vicinity of the discharge portion, the stability of the shape of the discharged droplet is improved (the variation in shape and size among the droplets). The variation in shape and size of the toner particles finally obtained is also reduced.
Examples of such a material having liquid repellency include fluorine resins such as polytetrafluoroethylene (PTFE), silicone materials, and the like.

As shown in FIG. 3, the piezoelectric element M22 includes a lower electrode (first electrode) M221, a piezoelectric body M222, and an upper electrode (second electrode) M223 that are stacked in this order. In other words, the piezoelectric element M22 has a configuration in which the piezoelectric body M222 is interposed between the upper electrode M223 and the lower electrode M221.
The piezoelectric element M22 functions as a vibration source, and the diaphragm M24 vibrates due to the vibration of the piezoelectric element (vibration source) M22 and has a function of instantaneously increasing the internal pressure of the dispersion liquid storage unit M21. It is.

  The head unit M2 is in a state where a predetermined ejection signal is not input from a piezoelectric element driving circuit (not shown), that is, a state where no voltage is applied between the lower electrode M221 and the upper electrode M223 of the piezoelectric element M22. Then, the piezoelectric body M222 is not deformed. For this reason, no deformation occurs in the diaphragm M24, and no volume change occurs in the dispersion liquid storage unit M21. Therefore, the aqueous suspension 3 is not discharged from the discharge part M23.

  On the other hand, when a predetermined ejection signal is input from the piezoelectric element drive circuit, that is, when a predetermined voltage is applied between the lower electrode M221 and the upper electrode M223 of the piezoelectric element M22, the piezoelectric body M222 is deformed. Arise. As a result, the diaphragm M24 bends greatly (deflects downward in FIG. 7), and the volume of the dispersion liquid storage unit M21 decreases (changes). At this time, the pressure in the dispersion liquid storage part M21 increases instantaneously, and the granular aqueous suspension 3 is discharged from the discharge part M23.

  When one discharge of the aqueous suspension 3 is completed, the piezoelectric element driving circuit stops applying the voltage between the lower electrode M221 and the upper electrode M223. Thereby, the piezoelectric element M22 returns almost to its original shape, and the volume of the dispersion liquid storage part M21 increases. At this time, pressure (pressure in the positive direction) from the aqueous suspension supply unit M4 toward the discharge unit M23 acts on the aqueous suspension 3. For this reason, air is prevented from entering the dispersion liquid storage part M21 from the discharge part M23, and an amount of the aqueous suspension 3 corresponding to the discharge amount of the aqueous suspension 3 is transferred from the aqueous suspension supply part M4 to the dispersion liquid. Supplied to the reservoir M21.

By applying the voltage as described above at a predetermined cycle, the piezoelectric element M22 vibrates and the granular aqueous suspension 3 is repeatedly discharged.
Thus, by discharging (injecting) the aqueous suspension 3 with the pressure pulse generated by the vibration of the piezoelectric body M222, the aqueous suspension 3 can be intermittently discharged one by one. The shape of the droplet 9 of the aqueous suspension 3 is stabilized. As a result, the variation in shape and size among the toner particles can be made particularly small, and the produced toner particles have high sphericity (geometrically close to a perfect sphere). Can be made relatively easy.

Further, by using the vibration of the piezoelectric body for discharging the dispersion liquid, the dispersion liquid can be discharged more reliably at a predetermined interval. For this reason, it is possible to effectively prevent the ejected droplets 9 from colliding with each other and agglomerating, and to more effectively prevent the formation of irregularly shaped dry fine particles 4.
The initial velocity of the aqueous suspension 3 (droplet 9) discharged from the head part M2 to the dispersion medium removing part M3 is, for example, preferably 0.1 to 10 m / second, and 2 to 8 m / second. Is more preferable. When the initial speed of the aqueous suspension 3 is less than the lower limit, toner productivity is reduced. On the other hand, when the initial speed of the aqueous suspension 3 exceeds the upper limit, the sphericity of the finally obtained toner particles tends to decrease.

  The viscosity of the aqueous suspension 3 discharged from the head M2 is not particularly limited, but is preferably 0.5 to 200 [mPa · s], for example, 1 to 25 [mPa · s]. More preferably. When the viscosity of the aqueous suspension 3 is less than the lower limit, it becomes difficult to sufficiently control the size of the discharged aqueous suspension 3 and the dispersion of finally obtained toner particles becomes large. There is. On the other hand, when the viscosity of the aqueous suspension 3 exceeds the upper limit, the diameter of the formed particles increases, the discharge speed of the aqueous suspension 3 decreases, and the energy required to discharge the aqueous suspension 3 The amount tends to increase. Further, when the viscosity of the aqueous suspension 3 is particularly large, the aqueous suspension 3 cannot be discharged as droplets.

Further, the aqueous suspension 3 discharged from the head M2 may be cooled in advance. By cooling the aqueous suspension 3 in this manner, for example, unintentional evaporation (volatilization) of the dispersion medium 32 from the aqueous suspension 3 in the vicinity of the discharge unit M23 can be effectively prevented. As a result, it is possible to effectively prevent a change in the discharge amount of the aqueous suspension 3 due to the decrease in the opening area of the discharge portion over time, and the variation in size and shape among the particles is particularly small. Toner can be obtained.
Moreover, although the discharge amount for one drop of the aqueous suspension 3 is slightly different depending on the content of the dispersoid 31 in the aqueous suspension 3, it is preferably 0.05 to 500 pl, 0.5 to More preferably, it is 50 pl. By setting the discharge amount of one drop of the aqueous suspension 3 to a value in such a range, the dried fine particles 4 to be formed can have an appropriate particle size.

  In the present embodiment, the content of the dispersoid 31 in the aqueous suspension 3 and the content of the dispersoid 31 in the aqueous suspension 3 are prevented so as to prevent the droplet 9 discharged from the discharge portion M23 (nozzle) from containing two or more dispersoids 31. The particle size is set. As a result, as shown in FIG. 3, the formed droplets 9 include one dispersoid 31 in the dispersion medium 32 or are substantially composed of only the dispersion medium 32 without the dispersoid 31. It will be.

Then, by removing the dispersion medium 32 from the droplet 9 containing one dispersoid 31 in the dispersion medium 32, the dry fine particles 4 derived from one dispersoid 31 are obtained. Therefore, only by making the dispersoid 31 have a uniform shape and a small width of the particle size distribution, the obtained dry fine particles 4 can also have a uniform shape and a small width of the particle size distribution.
On the other hand, the liquid droplets which are substantially free of the dispersoid 31 and are constituted only by the dispersion medium 32 are removed when the dispersion medium 32 is removed. Further, since the particle size of the dispersoid 31 with respect to the particle size of the droplet 9 is relatively large, even when a sub-droplet having a particle size smaller than the required main droplet is generated in forming the droplet, It is possible to prevent the dispersoid 31 from being present in the sub-droplet. Such a sub-droplet does not include the dispersoid 31 and is substantially composed only of the dispersion medium 32. Therefore, the dispersion medium 32 is removed and disappears, and the particle size distribution of the obtained dry fine particles 4 is reduced. Does not increase the width.

  The frequency (frequency of the piezoelectric pulse) of the piezoelectric element M22 is not particularly limited, but is preferably 1 kHz to 500 MHz, and more preferably 5 kHz to 200 MHz. When the frequency of the piezoelectric element M22 is less than the lower limit, toner productivity is reduced. On the other hand, when the vibration frequency of the piezoelectric element M22 exceeds the upper limit value, the discharge of the granular aqueous suspension 3 cannot follow, and the variation in size of one drop of the aqueous suspension 3 increases, resulting in formation. There is a possibility that the variation in the size of the dried fine particles (toner particles) 4 will increase.

The dry particle manufacturing apparatus M1 having the illustrated configuration has a plurality of head portions M2. Then, the granular aqueous suspension 3 (droplet 9) is discharged from each of the head portions M2 to the dispersion medium removing portion M3.
Each head portion M2 may discharge the aqueous suspension 3 (droplet 9) almost simultaneously, but at least two adjacent head portions discharge the aqueous suspension 3 (droplet 9). It is preferable that the timing is controlled to be different. This more effectively prevents the droplets 9 from colliding with each other before the dry fine particles 4 are formed from the droplets 9 ejected from the adjacent head part M2 to cause unintentional aggregation. Can do.

  Further, as shown in FIG. 2, the dry particulate manufacturing apparatus M1 has a gas flow supply means M10, and the gas supplied from the gas flow supply means M10 passes through the duct M101 to the head portion M2-. From each gas injection port M7 provided between the head parts M2, it becomes the structure injected by substantially uniform pressure. Thereby, it is possible to form the dry fine particles 4 while maintaining the interval between the droplets 9 intermittently ejected from the ejection unit M23 and effectively preventing the droplets 9 from colliding with each other. As a result, the variation in size and shape of the formed dry fine particles 4 can be further reduced.

  Further, by injecting the gas supplied from the gas flow supply means M10 from the gas injection port M7, a gas flow that flows in almost one direction (downward in the figure) can be formed in the dispersion medium removal unit M3. . When such a gas flow is formed, the dry fine particles 4 formed in the dispersion medium removing unit M3 can be transported more efficiently. Thereby, the collection efficiency of the dry fine particles 4 is improved, and the productivity of the liquid developer is improved.

Further, when gas is ejected from the gas ejection port M7, an airflow curtain is formed between the droplets 9 ejected from the respective head portions M2, for example, between the droplets ejected from the adjacent head portions. It is possible to more effectively prevent the collision and aggregation.
A heat exchanger M11 is attached to the gas flow supply means M10. Thereby, the temperature of the gas injected from the gas injection port M7 can be set to a preferable value, and the dispersion medium 32 can be efficiently removed from the granular aqueous suspension 3 discharged to the dispersion medium removal unit M3. Can do.

Further, with such a gas flow supply means M10, the removal rate of the dispersion medium 32 from the aqueous suspension 3 discharged from the discharge unit M23 can be easily adjusted by adjusting the supply amount of the gas flow. It is also possible to control.
Although the temperature of the gas injected from the gas injection port M7 differs depending on the composition of the dispersoid 31 and the dispersion medium 32 contained in the aqueous suspension 3, it is usually preferably 0 to 70 ° C. More preferably, it is 60 ° C. When the temperature of the gas ejected from the gas ejection port M7 is within such a range, the resulting dried fine particles 4 are contained in the droplets 9 while the shape uniformity and stability of the dried fine particles 4 are sufficiently high. The dispersion medium 32 can be efficiently removed.

  Further, the humidity of the gas injected from the gas injection port M7 is, for example, preferably 50% RH or less, and more preferably 30% RH or less. When the humidity of the gas injected from the gas injection port M7 is 50% RH or less, the dispersion medium 32 included in the aqueous suspension 3 can be efficiently removed in the dispersion medium removal unit M3 described later. The productivity of the dry fine particles 4 is further improved.

The dispersion medium removing unit M3 is configured by a cylindrical housing M31. For the purpose of keeping the temperature in the dispersion medium removal unit M3 within a predetermined range, for example, a heat source or a cooling source is installed inside or outside the housing M31, or a flow path for the heat medium or the cooling medium is formed in the housing M31. It may be a jacket.
The temperature in the housing M31 is preferably equal to or lower than the glass transition temperature of the dispersoid 31. In other words, it is preferable that the dry fine particle production process is performed at a temperature below the glass transition point of the dispersoid 31. This makes it difficult for the dispersoids 31 to stick to each other when forming the droplets 9 of the dispersion 3, thereby preventing the bonding between the dry fine particles 4 derived from the dispersoids 31.

  In the illustrated configuration, the pressure in the housing M31 is adjusted by the pressure adjusting means M12. Thus, by adjusting the pressure in the housing M31, the dry fine particles 4 can be formed more efficiently, and as a result, the productivity of the liquid developer is improved. In the configuration shown in the figure, the pressure adjusting means M12 is connected to the housing M31 by a connecting pipe M121. Further, an enlarged diameter portion M122 having an enlarged inner diameter is formed in the vicinity of an end portion of the connection pipe M121 connected to the housing M31, and a filter M123 for preventing the suction of the dry fine particles 4 and the like is further provided. ing.

  The pressure in the housing M31 is not particularly limited, but is preferably 150 kPa or less, more preferably 100 to 120 kPa, and even more preferably 100 to 110 kPa. If the pressure in the housing M31 is a value within the above range, for example, rapid removal of the dispersion medium 32 (boiling phenomenon) from the droplets 9 can be effectively prevented, and the irregularly shaped dry fine particles 4 can be prevented. The dry fine particles 4 can be more efficiently produced while sufficiently preventing the occurrence of the above. Note that the pressure in the housing M31 may be substantially constant at each part or may be different at each part.

The housing M31 is connected to voltage application means M8 for applying a voltage. By applying a voltage having the same polarity as that of the dry fine particles 4 (droplets 9) to the inner surface side of the housing M31 by the voltage applying means M8, the following effects can be obtained.
Usually, the dry fine particles 4 are charged positively or negatively. For this reason, if there is a charged substance charged with a polarity different from that of the dry fine particles 4, a phenomenon occurs in which the dry fine particles 4 are electrostatically attracted and attached to the charged substance. On the other hand, if there is a charged substance charged with the same polarity as the dry fine particles 4, the charged substance and the dry fine particles 4 repel each other, effectively preventing the phenomenon that the dry fine particles 4 adhere to the surface of the charged substance. be able to. Therefore, by applying a voltage having the same polarity as that of the granular dry fine particles 4 to the inner surface side of the housing M31, it is possible to effectively prevent the dry fine particles 4 from adhering to the inner surface of the housing M31. Thereby, generation | occurrence | production of the dry fine particle 4 of irregular shape can be prevented more effectively, and the collection | recovery efficiency of the dry fine particle 4 also improves.

Further, the housing M31 has a reduced diameter portion M311 in which the inner diameter decreases in the downward direction in FIG. 6 in the vicinity of the recovery portion M5. By forming such a reduced diameter portion M311, the dry fine particles 4 can be efficiently recovered.
Then, the dry fine particles 4 formed as described above are collected in the collection unit M5.
The dried fine particles 4 obtained as described above usually have a size and shape corresponding to each dispersoid 31. As a result, the finally obtained liquid developer contains toner particles having a relatively small particle diameter, high circularity (sphericity), and small variation in shape size among the particles.

Further, the dry fine particles 4 obtained as described above may be any granular material obtained by removing the dispersion medium 32 of the aqueous suspension 3. For example, a part of the dispersion medium remains in the interior. You may do it.
The obtained dry fine particles 4 may be directly subjected to a dispersion step described later or may be subjected to various treatments such as heat treatment. As a result, the mechanical strength (shape stability) of the dry fine particles can be further improved, and the water content in the dry fine particles can be reduced. Also, the water content can be reduced in the same manner as described above by subjecting the obtained dry fine particles 4 to a treatment such as aeration or leaving the dry fine particles 4 in a reduced pressure atmosphere.
Moreover, you may perform various processes, such as a classification process and an external addition process, with respect to the above-mentioned dry particulates 4 as needed.

<Dispersing process>
Next, the dried fine particles 4 obtained as described above are dispersed as toner particles in the insulating liquid 5 (dispersing step). Thereby, a liquid developer in which the toner particles as the dry fine particles 4 are dispersed in the insulating liquid 5 (supporting liquid) is obtained. In the present embodiment, the dry fine particles 4 taken out from the recovery unit M5 are charged into a container M6 that contains the insulating liquid 5 and stirred to obtain a liquid developer.

The insulating liquid is not particularly limited as long as it has insulating properties, and a known liquid blended in a liquid developer can be used. Specifically, the electrical resistance at room temperature (20 ° C.) ( The volume resistivity is preferably 10 ⁹ Ω · cm or more, more preferably 10 ¹¹ Ω · cm or more, and even more preferably 10 ¹³ Ω · cm or more.
The dielectric constant of the insulating liquid is preferably 3.5 or less.

More specifically, examples of the insulating liquid include saturated hydrocarbon compounds, silicone oils, vegetable oils, and the like.
Examples of the saturated hydrocarbon compound include octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, isoparaffin, normal paraffin, and the like. Examples of the oil include dimethylsilicone, methylphenylsilicone, cyclic dimethylpolysiloxane, and fluorosilicone. Examples of the vegetable oil include soybean oil, sunflower oil, rapeseed oil, castor oil, linseed oil, and modified oils thereof. Of these, one of them can be used alone or two or more of them can be used in combination.

  Specific examples of commercially available products of this insulating liquid include petroleum-based saturated hydrocarbon compounds such as Isopar G, H, L, M (trade names manufactured by Exxon Chemical) and Norpar 12 (trade names manufactured by Exxon Chemical). Cielsol 70, Cielsol 71 (Cielsol; trade name of Ciel Oil), Amsco OMS, Amsco 460 solvent (Amsco; trade name of Spirits), and the like. Examples of silicone oil include SH-200 (Toray Dow). -Coming Silicone Co., Ltd. trade name), KF-96 (Shin-Etsu Chemical Co., Ltd. trade name), L-45 (Nihon Unicar Co., Ltd. trade name), and the like.

By using the insulating liquid as described above, the toner particles of the obtained liquid developer have excellent charging characteristics.
In addition, for the purpose of improving the dispersibility of the toner particles, adjusting the charge of the toner particles, adjusting the viscosity of the liquid developer, and the like for the insulating liquid, a metal soap such as a metal salt of octylic acid or a metal salt of naphthenic acid or titanium It may contain known charge control agents such as alkoxides and aluminum-containing chelate compounds, and also surfactants such as dodecyltrimethylammonium chloride and alkylbenzenesulfonate, fatty acid ester compounds and derivatives thereof, silica fine particles, An additive such as solid fine particles insoluble in an insulating liquid such as alumina fine particles and titania fine particles may be contained.

Further, the volume resistivity of the insulating liquid is preferably 1 × 10 ⁹ to 1 × 10 ¹⁸ Ω · cm, and more preferably 1 × 10 ¹¹ to 1 × 10 ¹⁸ Ω · cm. Thereby, the toner particles of the obtained liquid developer have excellent charging characteristics.
The viscosity of the insulating liquid is not particularly limited, but is preferably, for example, 10 to 10000 [mPa · s], and more preferably 50 to 1000 [mPa · s]. Thereby, the dispersibility of the dry fine particles 4 can be improved while the handling property of the liquid developer at the time of manufacture and use is excellent.

  The dispersion of the dry fine particles 4 in the insulating liquid may be performed by any method, but is preferably performed by adding the dry fine particles 4 to the stirred insulating liquid. As a result, the liquid developer obtained can stably maintain a good dispersion state of toner particles for a long period of time while preventing unintentional aggregation of the dry fine particles 4 during the preparation of the liquid developer. it can.

<Liquid developer>
The average particle size of the toner particles in the liquid developer obtained as described above is preferably 0.1 to 5 μm, more preferably 0.4 to 4 μm, and 0.5 to 3 μm. Is more preferable. When the average particle diameter of the toner particles is within the above range, the dispersion of characteristics such as charging characteristics and fixing characteristics among the toner particles is particularly small, and the reliability of the entire liquid developer is particularly high. In addition, the resolution of the image formed by the liquid developer (toner) can be made sufficiently high.

The standard deviation of the particle size between toner particles constituting the liquid developer is preferably 3.0 μm or less, more preferably 0.1 to 2 μm, and preferably 0.1 to 1.0 μm. More preferably. As a result, variations in characteristics such as charging characteristics and fixing characteristics among the toner particles are particularly reduced, and the reliability of the entire liquid developer is further improved.
Further, the average value (average circularity) of the circularity R represented by the following formula (I) for the toner particles constituting the liquid developer is preferably 0.85 or more, and 0.90 to 0.00. 99 is more preferable, and 0.95-0.99 is even more preferable.
R = L ₀ / L ₁ (I)
(Where L ₁ [μm] is the circumference of the projected image of the toner particles to be measured, and L ₀ [μm] is the circumference of a perfect circle having an area equal to the area of the projected image of the toner particles to be measured. Represents length)

Thereby, the transfer efficiency and mechanical strength of the toner particles can be made particularly excellent while the particle diameter of the toner particles is sufficiently small.
The standard deviation of the average circularity between the toner particles constituting the liquid developer is preferably 0.15 or less, more preferably 0.001 to 0.10, and 0.001 to 0. More preferably, .05. As a result, variations in characteristics such as charging characteristics and fixing characteristics among the toner particles are particularly reduced, and the reliability of the entire liquid developer is further improved.
Further, the content of the toner particles (dried fine particles 4) in the liquid developer is preferably 5 to 50 wt%, and more preferably 10 to 35 wt%.
As a result, the image density is sufficiently secured and the dispersion of the toner particles in the liquid developer is stabilized, so that the effect of stabilizing the image quality over a long period of time can be obtained.

As described above, in the present embodiment, the droplet 9 ejected from the ejection unit M23 (nozzle) is prevented from containing two or more dispersoids 31 and the formed droplet 9 is dispersed. It is assumed that the medium 32 includes one dispersoid 31 or that the medium 32 does not include the dispersoid 31 and is substantially constituted only by the dispersion medium 32.
Then, by removing the dispersion medium 32 from the droplet 9 containing one dispersoid 31 in the dispersion medium 32, the dry fine particles 4 derived from one dispersoid 31 are obtained. Therefore, only by making the dispersoid 31 have a uniform shape and a small width of the particle size distribution, the obtained dry fine particles 4 can also have a uniform shape and a small width of the particle size distribution.

  On the other hand, the liquid droplets which are substantially free of the dispersoid 31 and are constituted only by the dispersion medium 32 are removed when the dispersion medium 32 is removed. Further, since the particle size of the dispersoid 31 with respect to the particle size of the droplet 9 is relatively large, even when a sub-droplet having a particle size smaller than the required main droplet is generated in forming the droplet, The presence of the dispersoid 31 in the sub-droplet can be prevented. Such a sub-droplet does not include the dispersoid 31 and is substantially composed only of the dispersion medium 32. Therefore, the dispersion medium 32 is removed and disappears, and the particle size distribution of the obtained dry fine particles 4 is reduced. Does not increase the width.

In particular, since the aqueous dispersion (aqueous suspension 3) is used, it is possible to produce a liquid developer in which toner particles having a uniform shape and a small width of particle size distribution are dispersed by an environmentally friendly method. Further, the dry fine particles 4 contain water and have excellent dispersibility in the insulating liquid 5. As a result, the obtained liquid developer has excellent storage stability.
In the present invention, toner particles may be obtained as an aggregate of the dispersoid 31. In this case, even if the particle size and shape of the dispersoid 31 vary, the total amount of the dispersoid 31 contained in the droplets 9 can be made substantially equal between the droplets 9. Therefore, even if the particle size and shape of the dispersoid 31 vary, the particle size and shape of the toner particles can be made uniform. As a result, a liquid developer having a uniform shape and having dispersed therein toner particles having a small particle size distribution width can be produced efficiently (with good productivity).

Next, a preferred embodiment of the image forming apparatus to which the liquid developer of the present invention as described above is applied will be described.
FIG. 8 shows an example of a contact-type image forming apparatus to which the liquid developer of the present invention is applied. The image forming apparatus P1 includes a drum of a cylindrical photosensitive member P2, and after the surface is uniformly charged by a charger P3 made of epichlorohydrin rubber or the like, information to be recorded by a laser diode or the like In accordance with the exposure P4, an electrostatic latent image is formed.

  The developing device P10 includes a coating roller P12 and a developing roller P13, part of which is immersed in a developer container P11. The application roller P12 is, for example, a metal gravure roller such as stainless steel, and rotates to face the developing roller P13. Further, a liquid developer coating layer P14 is formed on the surface of the coating roller P12, and the thickness thereof is kept constant by the metering blade P15.

  Then, the liquid developer is transferred from the coating roller P12 to the developing roller P13. The developing roller P13 has a low hardness silicone rubber layer on a roller core P16 made of metal such as stainless steel, and a conductive PFA (polytetrafluoroethylene-perfluorovinyl ether copolymer) resin on the surface thereof. A layer is formed, and rotates at the same speed as the photosensitive member P2 to transfer the liquid developer to the latent image portion. The liquid developer remaining on the developing roller P13 after being transferred to the photoreceptor P2 is removed by the developing roller cleaning blade P17 and collected in the developer container P11.

Further, after the transfer of the toner image from the photoconductor to the intermediate transfer roller, the photoconductor is neutralized by the neutralizing light P21, and the residual transfer toner remaining on the photoconductor is a cleaning made of urethane rubber or the like. It is removed by the blade P22.
Similarly, residual toner remaining on the intermediate transfer roller P18 after transfer from the intermediate transfer roller P18 to the information recording medium P20 is removed by a cleaning blade P23 made of urethane rubber or the like.
After the toner image formed on the photoreceptor P2 is transferred to the intermediate transfer roller P18, a transfer current is passed through the secondary transfer roller P19, and the information recording medium P20 such as paper passing between them. The toner image on the information recording medium P20 such as paper is fixed using the fixing device shown in FIG.

  FIG. 9 shows an example of a non-contact type image forming apparatus to which the liquid developer of the present invention is applied. In the non-contact method, the developing roller P13 is provided with a charging blade P24 made of a phosphor bronze plate having a thickness of 0.5 mm. The charging blade P24 has a function of making frictional charging in contact with the liquid developer layer, and since the application roller P12 is a gravure roll, a developer layer corresponding to the unevenness of the surface of the gravure roll is formed on the development roller P13. Therefore, it functions to uniformly level the unevenness, and the arrangement direction may be either the counter direction or the trail direction with respect to the rotation direction of the developing roller, and may be a roller shape instead of a brate shape.

Further, an interval of 200 μm to 800 μm is provided between the developing roller P13 and the photosensitive member P2, and a frequency of 500 to 3000 Vpp superimposed on a direct current voltage of 200 to 800 V is applied between the developing roller P13 and the photosensitive member P2. An AC voltage of 50 to 3000 Hz is preferably applied. The rest is the same as the image forming apparatus described with reference to FIG.
In FIGS. 8 and 9, image formation using a single color liquid developer has been described. However, in the case of forming an image using a plurality of color toners, each color image is formed using a plurality of color developers. Thus, a color image can be formed.

  FIG. 10 is a cross-sectional view of the fixing device. F1 is a heat fixing roll, F1a is a halogen lamp, F1b is a roll base, F1c is an elastic body, F2 is a pressure roll, F2a is a rotating shaft, F2b is a roll base, F2c is an elastic body, F3 is a heat-resistant belt, F4 is a belt tension member, F4a is a protruding wall, F5 is a sheet material, F5a is an unfixed toner image, F6 is a cleaning member, F7 is a frame, F9 is a spring, and L is pressing It is a part tangent.

As shown in the figure, the fixing device F40 includes a heat fixing roll (hereinafter also referred to as a heating roll) F1, a pressure roll F2, a heat-resistant belt F3, a belt stretching member F4, and a cleaning member F6.
The heat fixing roll F1 is formed by covering a pipe member having an outer diameter of about 25 mm and a wall thickness of about 0.7 mm with a roll base material F1b and an elastic body F1c having a thickness of about 0.4 mm on the outer periphery thereof. 1,050W as a heat source and two columnar halogen lamps F1a are built in and can be rotated counterclockwise as indicated by an arrow in the figure. Further, the pressure roll F2 has a pipe material having an outer diameter of about 25 mm and a wall thickness of about 0.7 mm as a roll base material F2b with a thickness of 0. The elastic body F2c having a thickness of about 2 mm is formed so as to cover the heat fixing roll F1 and the pressure roll F2 with a pressure contact force of 10 kg or less, a nip length of about 10 mm, and disposed opposite the heat fixing roll F1. It can be rotated in the clockwise direction indicated by an arrow.

  Thus, since the outer diameters of the heat fixing roll F1 and the pressure roll F2 are configured to be as small as about 25 mm, the sheet material F5 after fixing does not wrap around the heat fixing roll F1 or the heat-resistant belt F3. A means for forcibly removing the sheet material is not necessary. Further, by providing a PFA layer of about 30 μm on the surface layer of the elastic body F1c of the heat fixing roll F1, the rigidity is improved accordingly. Thereby, although the thicknesses of the elastic bodies F1c and F2c are different, the elastic bodies F1c and F2c are substantially uniformly elastically deformed to form a so-called horizontal nip, and with respect to the peripheral speed of the heat fixing roll F1. Since there is no difference in the conveyance speed of the heat-resistant belt F3 or the sheet material F5, extremely stable image fixing is possible.

  In addition, two halogen lamps F1a and F1a constituting a heating source are built in the heat fixing roll F1, and the heating elements of these halogen lamps F1a and F1a are arranged at different positions. The halogen lamps F1a and F1a are selectively turned on, so that the fixing nip portion where the heat-resistant belt F3 is wound around the heat fixing roll F1 and the portion where the belt stretching member F4 is in sliding contact with the heat fixing roll F1 are different. Temperature control can be easily performed under conditions and different conditions between a wide sheet material and a narrow sheet material.

  The heat-resistant belt F3 is an endless annular belt which is stretched around the outer periphery of the pressure roll F2 and the belt tension member F4 and is movable, and is sandwiched between the heat fixing roll F1 and the pressure roll F2. is there. The heat-resistant belt F3 has a thickness of 0.03 mm or more, and its front surface (the surface on which the sheet material F5 comes into contact) is formed of PFA, and the back surface (contacts with the pressure roll F2 and the belt stretching member F4). It is formed of a seamless tube having a two-layer structure in which the surface on the side to be formed is made of polyimide. The heat-resistant belt F3 is not limited to this, and can be formed of other materials such as a metal tube such as a stainless steel tube or a nickel electroformed tube, or a heat-resistant resin tube such as silicon.

  The belt stretching member F4 is disposed upstream of the fixing nip portion between the heat fixing roll F1 and the pressure roll F2 in the conveying direction of the sheet material F5, and has an arrow P around the rotation axis F2a of the pressure roll F2. It is arranged so that it can swing in the direction. The belt stretching member F4 is configured to stretch the heat-resistant belt F3 in the tangential direction of the heat fixing roll F1 in a state where the sheet material F5 does not pass through the fixing nip portion. If the fixing pressure is large at the initial position where the sheet material F5 enters the fixing nip portion, the entry may not be smoothly performed and the sheet material F5 may be fixed with the leading end of the sheet material F5 broken. By adopting a configuration in which F3 is stretched in the tangential direction of the heat fixing roll F1, an introduction port portion of the sheet material F5 through which the sheet material F5 smoothly enters can be formed, and to the stable fixing nip portion of the sheet material F5. Can enter.

  The belt stretching member F4 is inserted into the inner periphery of the heat-resistant belt F3 and cooperates with the pressure roll F2 to apply a tension f to the heat-resistant belt F3 (the heat-resistant belt F3 is a belt). Sliding on the tension member F4). The belt stretching member F4 is disposed at a position where the heat-resistant belt F3 is wound around the heat fixing roll F1 side from the pressing portion tangent L between the heat fixing roll F1 and the pressure roll F2 to form a nip. The protruding wall F4a protrudes from one end or both ends of the belt stretching member F4 in the axial direction. The protruding wall F4a is formed by the heat-resistant belt F3 when the heat-resistant belt F3 approaches one of the axial ends. The contact to the end of the heat-resistant belt F3 is regulated by contacting the wall F4a. A spring F9 is contracted between the end of the protruding wall F4a opposite to the heat fixing roll F1 and the frame, and the protruding wall F4a of the belt stretching member F4 is lightly pressed by the heat fixing roll F1, so that the belt tension is increased. The frame member F4 is positioned in sliding contact with the heat fixing roll F1.

  In order to stretch the heat-resistant belt F3 with the pressure roll F2 and the belt stretching member F4 and drive it stably with the pressure roll F2, the friction coefficient between the pressure roll F2 and the heat-resistant belt F3 is changed to the belt stretching member. It is good to set larger than the friction coefficient of F4 and heat-resistant belt F3. However, the friction coefficient is such that foreign matter enters between the heat-resistant belt F3 and the pressure roll F2 or between the heat-resistant belt F3 and the belt stretching member F4, or the heat-resistant belt F3, the pressure roll F2, and the belt stretching member. It may become unstable due to wear of the contact portion with F4.

  Therefore, the belt tension member F4 and the heat-resistant belt F3 have a winding angle smaller than the winding angle of the pressure roll F2 and the heat-resistant belt F3, and the diameter of the belt stretching member F4 is smaller than the diameter of the pressure roll F2. Set as follows. As a result, the length that the heat-resistant belt F3 slides on the belt stretching member F4 is shortened, which can be avoided from instability factors such as changes with time and disturbances, and the heat-resistant belt F3 is stably driven by the pressure roll F2. Will be able to.

  Further, a cleaning member F6 is disposed between the pressure roll F2 and the belt stretching member F4. The cleaning member F6 is in sliding contact with the inner peripheral surface of the heat-resistant belt F3, and foreign matter on the inner peripheral surface of the heat-resistant belt F3. It cleans and wear powder. By cleaning the foreign matter, wear powder, and the like in this way, the heat-resistant belt F3 is refreshed, and the above-described factor of instability of the friction coefficient is removed. Further, the belt tension member F4 is provided with a recess F4f, and the recess F4f is suitable for storing foreign matter, abrasion powder, and the like removed from the heat-resistant belt F3.

  The position where the belt tension member F4 is lightly pressed against the heat fixing roll F1 is the nip initial position, and the position where the pressure roll F2 is pressed against the heat fixing roll F1 is the nip end position. Then, the sheet material F5 enters the fixing nip portion from the initial nip position, passes between the heat-resistant belt F3 and the heat fixing roll F1, and exits from the nip end position, whereby an unfixed sheet formed on the sheet material F5. The toner image F5a is fixed, and then discharged in the tangential direction L of the pressing portion of the pressure roll F2 to the heat fixing roll F1.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to this.
For example, each part constituting the dry fine particle production apparatus can be replaced with an arbitrary one that exhibits the same function, or another structure can be added.
Further, the liquid developer of the present invention is not limited to those applied to the image forming apparatus as described above.

  In the above-described embodiment, the dry fine particles obtained in the dispersion medium removing step are once collected and then used for the dispersion step. However, the dry fine particles are directly collected in the dispersion step without being collected as a powder. May be provided. For example, the dry fine particle manufacturing apparatus as shown in the figure may have a dispersion unit that stores the insulating liquid and is supplied with the manufactured dry fine particles. Thereby, while being able to manufacture a liquid developer more efficiently, unintentional aggregation between dry fine particles etc. can be prevented more effectively.

Further, as shown in FIG. 11, an acoustic lens (concave lens) M25 may be installed in the head portion M2. By installing such an acoustic lens M25, for example, the pressure pulse (vibration energy) generated by the piezoelectric element M22 can be converged by the pressure pulse converging unit M26 in the vicinity of the ejection unit M23. As a result, the vibration energy generated by the piezoelectric element M22 can be efficiently used as energy for discharging the aqueous suspension 3. Therefore, even if the aqueous suspension 3 stored in the dispersion liquid storage unit M21 has a relatively high viscosity, it can be reliably discharged from the discharge unit M23. Further, even if the aqueous suspension 3 stored in the dispersion liquid storage unit M21 has a relatively large cohesive force (surface tension), it can be discharged as fine droplets. In addition, the particle size of the dry fine particles (toner particles) 9 can be controlled to a relatively small value.
Thus, by adopting the configuration as shown in the figure, the dry fine particles 4 can be formed in a desired shape, even when a higher viscosity material or a material having a high cohesive force is used as the aqueous suspension 3. Since the size can be controlled, the range of material selection is particularly wide, and a toner having desired characteristics can be obtained more easily.

  Further, in the case of the configuration shown in the figure, since the aqueous suspension 3 is discharged by the converged pressure pulse, the aqueous suspension to be discharged is discharged even when the area (opening area) of the discharge portion M23 is relatively large. The size of the liquid 3 can be made relatively small. That is, even when it is desired to make the particle size of the dry fine particles 4 relatively small, the area of the discharge portion M23 can be increased. Thereby, even if the aqueous suspension 3 has a relatively high viscosity, it is possible to more effectively prevent the occurrence of clogging in the discharge part M23.

The acoustic lens is not limited to a concave lens, and for example, a Fresnel lens, an electronic scanning lens, or the like may be used.
Furthermore, as shown in FIGS. 12 to 14, a diaphragm member M13 having a converging shape may be disposed between the acoustic lens M25 and the discharge unit M23 toward the discharge unit M23. Thereby, the convergence of the pressure pulse (vibration energy) generated by the piezoelectric element M22 can be assisted, and the pressure pulse generated by the piezoelectric element M22 can be used more efficiently.

In the above-described embodiment, the toner component is described as a solid component contained in the dispersoid. However, at least a part of the toner component may be contained in the dispersion medium.
In the above-described embodiment, the dispersion liquid (aqueous suspension) is intermittently ejected from the head portion by the piezoelectric pulse. However, another method is used as the dispersion liquid ejection method (injection method). You can also For example, as a method for discharging (injecting) the dispersion liquid, a method such as a spray drying method or a so-called bubble jet (“Bubble Jet” is a registered trademark) method is used, and “the dispersion liquid is pressed against a smooth surface with a gas flow. A method of injecting a dispersion into droplets using a nozzle that is thinly stretched to form a thin laminar flow and ejects the thin laminar flow as fine droplets away from the smooth surface (Japanese Patent Application No. 2002-321889). Or the like) ”or the like. The spray drying method is a method of obtaining liquid droplets by spraying (spraying) a liquid (dispersion) using a high-pressure gas. Moreover, as a method to which a so-called bubble jet (“bubble jet” is a registered trademark) method is applied, a method described in the specification of Japanese Patent Application No. 2002-169348 can be cited. That is, as a method for ejecting (injecting) the dispersion liquid, a “method for intermittently ejecting the dispersion liquid from the head portion by a change in gas volume” can be applied.

Further, in the above-described embodiment, it has been described that dry fine particles having a size and shape corresponding to each dispersoid in the aqueous suspension are obtained. However, the dry fine particles are, for example, a plurality of dispersions of the aqueous suspension. Aggregates formed by agglomerating (bonding) fine particles corresponding to the quality may be used.
In the above-described embodiment, the aqueous emulsion is prepared using the pulverized product of the kneaded product, but the pulverizing step of the kneaded product may be omitted.

Moreover, the preparation method of an aqueous emulsion and aqueous suspension is not limited to the method as mentioned above. For example, the dispersion in which the solid state dispersoid is dispersed may be heated so that the dispersoid is once liquefied to obtain an aqueous emulsion, and the aqueous emulsion may be cooled to obtain an emulsion suspension.
In the above-described embodiment, the aqueous suspension is once obtained using the aqueous emulsion, and then the dry fine particles are produced using the aqueous suspension. However, the aqueous suspension is used. Alternatively, a configuration in which dry fine particles are obtained directly from an aqueous emulsion may be used. For example, dry fine particles may be obtained by discharging an aqueous emulsion into droplets and removing the dispersion medium together with the solvent in the dispersion medium from the droplets.

[1] Production of toner (Example 1)
<Manufacture of colorant (microencapsulated pigment)>
Prior to toner production, the following colorants were produced.
First, a carbon black pigment composed of pigment particles having a cationic group on the surface was prepared.

4 g of Aqualon KH-10 represented by the following general formula as an anionic polymerizable surfactant was added to and mixed with an aqueous dispersion obtained by dispersing 15 g of this carbon black pigment in 75 g of ion-exchanged water. Was irradiated for 15 minutes. Next, 2 g of anionic polymerizable surfactant Aqualon KH-10 and 20 g of ion-exchanged water were added and mixed, and then ultrasonic waves were irradiated again for 30 minutes. This was put into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a temperature controller, a nitrogen introduction tube and an ultrasonic generator. After the internal temperature of the reaction vessel was raised to 80 ° C., an aqueous potassium persulfate solution in which 0.03 g of potassium persulfate was dissolved as a polymerization initiator was added dropwise to 10 g of ion-exchanged water. Polymerized for hours. After the polymerization is completed, the pH is adjusted to 8 and unreacted substances are removed by ultrafiltration. Then, coarse particles are removed by a membrane filter having a pore size of 1 μm to obtain a dispersion of the target microencapsulated pigment “AMP carbon black”. Obtained.
The volume average particle diameter of the obtained dispersion was measured using a laser Doppler type particle size distribution analyzer Microtrac UPA150 manufactured by Leeds & Northrop Co. As a result, it was 130 nm.
Thereafter, the dispersion was heated and dried under reduced pressure to obtain an AMP carbon black pigment.

<Manufacture of toner>
First, as a binder resin, an epoxy resin (softening temperature: 97 ° C.): 80 parts by weight and an AMP carbon black pigment as a colorant: 20 parts by weight were prepared.
These components were mixed using a 20 L type Henschel mixer to obtain a raw material for toner production.

Next, this raw material (mixture) was kneaded using a twin-screw kneading extruder (Ikegai, PCM-30) as shown in FIG.
The total length of the process part of the biaxial kneading extruder was 160 cm.
Moreover, it set so that the temperature of the raw material in a process part might be 130-140 degreeC.
The screw rotation speed was 120 rpm, and the raw material charging speed was 20 kg / hour.

The time required for the raw material to pass through the process part, determined from such conditions, is about 4 minutes.
The kneading as described above was performed while degassing the inside of the process unit by operating a vacuum pump connected to the process unit via a degassing port.
The raw material (kneaded material) kneaded in the process part was extruded outside the biaxial kneading extruder through the head part. The temperature of the kneaded material in the head part was adjusted to 110 ° C.

Thus, the kneaded material extruded from the extrusion port of the biaxial kneading extruder was cooled using a cooling machine as shown in FIG. The temperature of the kneaded material immediately after the cooling step was about 45 ° C.
The cooling rate of the kneaded product was 9 ° C./second. In addition, the time required from the end of the kneading process to the end of the cooling process was 10 seconds.
The kneaded material cooled as described above was coarsely pulverized to obtain a powder having an average particle size of 1.5 mm. A hammer mill was used for coarse pulverization of the kneaded product.

Next, 100 parts by weight of the coarsely pulverized product of the kneaded product was added to 250 parts by weight of toluene, and the mixture was treated with an ultrasonic homogenizer (output: 400 μA) for 1 hour to dissolve the epoxy resin of the kneaded product. A solution was obtained.
On the other hand, an aqueous liquid composed of 700 parts by weight of ion-exchanged water was prepared.
The stirring speed of the aqueous liquid was adjusted with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.).

The above solution (a kneaded toluene solution) was dropped into the agitated aqueous liquid. As a result, an aqueous emulsion in which the dispersoid having an average particle diameter of 2.6 μm was uniformly dispersed was obtained.
Thereafter, toluene in the aqueous emulsion was removed under the conditions of temperature, 100 ° C., and atmospheric pressure: 80 kPa, and further cooled to room temperature to obtain an aqueous suspension in which solid fine particles were dispersed. In the obtained aqueous suspension, substantially no toluene remained. The solid content (dispersoid) concentration of the obtained aqueous suspension was 28.8 wt%. The average particle size of the dispersoid (solid fine particles) dispersed in the suspension was 1.5 μm. The average particle size of the dispersoid was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

  The suspension obtained as described above was charged into the aqueous suspension supply unit of the dry particle manufacturing apparatus having the configuration shown in FIGS. While stirring the aqueous suspension in the aqueous suspension supply unit with the stirring means, the aqueous suspension was supplied to the head unit by a metering pump and discharged (injected) from the discharge unit to the dispersion medium removal unit. The discharge part had a circular shape with a diameter of 25 μm. Further, as the head portion, a head portion that has been subjected to a hydrophobic treatment with a fluororesin (polytetrafluoroethylene) coat in the vicinity of the discharge portion is used. The temperature of the aqueous suspension in the aqueous suspension supply unit was adjusted to 25 ° C.

  For the discharge of the aqueous suspension, the temperature of the dispersion liquid in the head part is 25 ° C., the frequency of the piezoelectric body is 10 kHz, the initial speed of the dispersion liquid discharged from the discharge part is 3 m / second, and the aqueous suspension is discharged from the head part. It was performed in a state where the discharge amount of one drop of the turbid liquid was adjusted to 0.4 pl (particle size: 2.08 μm). In addition, the aqueous suspension was discharged so that the discharge timing of the aqueous suspension was shifted at least between the head portions adjacent to each other among the plurality of head portions.

  Further, when discharging the aqueous suspension, air having a temperature of 25 ° C., a humidity of 27% RH, and a flow velocity of 3 m / sec was jetted vertically downward from the gas injection port. The temperature (atmosphere temperature) in the housing was set to 45 ° C. The pressure in the housing was about 1.5 kPa. The length of the dispersion medium removing portion (length in the transport direction) was 1.0 m.

In addition, a voltage was applied to the housing of the dispersion medium removing portion so that the potential on the inner surface side was −200 V, thereby preventing the aqueous suspension (dry fine particles) from adhering to the inner wall.
In the dispersion medium removing section, the dispersion medium was removed from the discharged aqueous suspension, and a large number of dry fine particles (toner particles) having a shape and size corresponding to each dispersoid were formed. The volume standard average particle diameter of the toner particles was 1.2 μm.

Next, the recovered dry fine particles were dispersed in an insulating liquid to obtain a liquid developer. As the insulating liquid, (saturated fatty acid: 14.4 wt%, linoleic acid: 54.7 wt%, other unsaturated fatty acid: 30.9 wt%) 400 parts by weight, and 100 parts by weight of linoleic acid glyceride purified from sunflower oil A mixture of 1 part by weight of a surfactant (dodecyltrimethylammonium chloride) and 5 parts by weight of α-tocopherol as an antioxidant was used. The insulating liquid had an electric resistance (volume resistivity) at room temperature (20 ° C.) of 1.5 × 10 ¹⁵ Ω · cm, and the insulating liquid had a relative dielectric constant of 2.2. Further, the content of the dry fine particles in the obtained liquid developer was 15 wt%.

(Example 2)
A liquid developer was produced in the same manner as in Example 1 except that the colorant produced as described below was used and a polyester resin (softening temperature: 99 ° C.) was used as the binder resin.
<Manufacture of colorant (microencapsulated pigment)>
First, a cyan pigment (CI Pigment Blue 15: 3) composed of pigment particles having a cationic group on the surface was prepared.

4 g of Aqualon KH-10 as an anionic polymerizable surfactant was added to and mixed with an aqueous dispersion in which 15 g of cyan pigment particles were dispersed in 75 g of ion-exchanged water, and then irradiated with ultrasonic waves for 15 minutes. Next, 6 g of benzyl methacrylate, 4 g of dodecyl methacrylate, 2 g of anionic polymerizable surfactant Aqualon KH-10, 0.5 g of 2-acrylamido-2-methylpropanesulfonic acid and 50 g of ion-exchanged water as hydrophilic monomers were added. Then, the mixture was again irradiated with ultrasonic waves for 30 minutes. This was put into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a temperature controller, a nitrogen introduction tube and an ultrasonic generator. After the internal temperature of the reaction vessel was raised to 80 ° C., an aqueous potassium persulfate solution in which 0.4 g of potassium persulfate was dissolved as a polymerization initiator was added dropwise to 20 g of ion-exchanged water. Polymerized for hours. After the polymerization is completed, the pH is adjusted to 8, and unreacted substances are removed by ultrafiltration. Then, coarse particles are removed by a membrane filter having a pore size of 1 μm to obtain a dispersion of the desired microencapsulated pigment “AMP cyan pigment”. Obtained.
The volume average particle diameter of the obtained dispersion was measured using a laser Doppler type particle size distribution analyzer Microtrac UPA150 manufactured by Leeds & Northrop Co. As a result, it was 130 nm.
Thereafter, the dispersion was heated and dried under reduced pressure to obtain an AMP cyan pigment.

(Example 3)
A liquid developer was produced in the same manner as in Example 1 except that the colorant produced as follows was used.
<Manufacture of colorant (microencapsulated pigment)>
First, a yellow pigment composed of pigment particles having a cationic group on the surface (CI Pigment Yellow 180) was prepared.

4 g of Aqualon KH-10 as an anionic polymerizable surfactant was added to and mixed with an aqueous dispersion obtained by dispersing 15 g of this yellow pigment particle in 75 g of ion-exchanged water, and then irradiated with ultrasonic waves for 15 minutes. Next, 6 g of benzyl methacrylate, 4 g of dodecyl methacrylate, 2 g of anionic polymerizable surfactant Aqualon KH-10, 0.5 g of 2-acrylamido-2-methylpropanesulfonic acid and 50 g of ion-exchanged water as hydrophilic monomers were added. Then, the mixture was again irradiated with ultrasonic waves for 30 minutes. This was put into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a temperature controller, a nitrogen introduction tube and an ultrasonic generator. After the internal temperature of the reaction vessel was raised to 80 ° C., an aqueous potassium persulfate solution in which 0.4 g of potassium persulfate was dissolved as a polymerization initiator was added dropwise to 20 g of ion-exchanged water. Polymerized for hours. After the polymerization is completed, the pH is adjusted to 8, and unreacted substances are removed by ultrafiltration. Then, coarse particles are removed by a membrane filter having a pore size of 1 μm to obtain a dispersion of the target microencapsulated pigment “AMP yellow pigment”. Obtained.
The volume average particle diameter of the obtained dispersion was measured using a laser Doppler type particle size distribution analyzer Microtrac UPA150 manufactured by Leeds & Northrop Co. As a result, it was 130 nm.
Thereafter, the dispersion was heated and dried under reduced pressure to obtain an AMP yellow pigment.

Example 4
A liquid developer was produced in the same manner as in Example 2 except that the colorant produced as described below was used.
<Manufacture of colorants>
First, a magenta pigment (CI Pigment Red 122) composed of pigment particles having a cationic group on the surface was prepared.

4 g of Aqualon KH-10 as an anionic polymerizable surfactant was added to and mixed with an aqueous dispersion obtained by dispersing 15 g of this magenta pigment particle in 75 g of ion-exchanged water, and then irradiated with ultrasonic waves for 15 minutes. Next, 6 g of benzyl methacrylate, 4 g of dodecyl methacrylate, 2 g of anionic polymerizable surfactant Aqualon KH-10, 0.5 g of 2-acrylamido-2-methylpropanesulfonic acid and 50 g of ion-exchanged water as hydrophilic monomers were added. Then, the mixture was again irradiated with ultrasonic waves for 30 minutes. This was put into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a temperature controller, a nitrogen introduction tube and an ultrasonic generator. After the internal temperature of the reaction vessel was raised to 80 ° C., an aqueous potassium persulfate solution in which 0.4 g of potassium persulfate was dissolved as a polymerization initiator was added dropwise to 20 g of ion-exchanged water. Polymerized for hours. After the polymerization is completed, the pH is adjusted to 8, and unreacted substances are removed by ultrafiltration. Then, coarse particles are removed by a membrane filter having a pore size of 1 μm to obtain a dispersion of the target microencapsulated pigment “AMP magenta pigment”. Obtained.
The volume average particle diameter of the obtained dispersion was measured using a laser Doppler type particle size distribution analyzer Microtrac UPA150 manufactured by Leeds & Northrop Co. As a result, it was 130 nm.
Thereafter, the dispersion was heat-dried under reduced pressure to obtain an AMP magenta pigment.

(Comparative Example 1)
A liquid developer was produced in the same manner as in Example 1 except that the pigment particles were not encapsulated.
(Comparative Example 2)
A liquid developer was produced in the same manner as in Example 2 except that the pigment particles were not encapsulated.

(Comparative Example 3)
A liquid developer was produced in the same manner as in Example 3 except that the pigment particles were not encapsulated.
(Comparative Example 4)
A liquid developer was produced in the same manner as in Example 4 except that the pigment particles were not encapsulated.

[2] Evaluation Each toner obtained as described above was evaluated for charging uniformity, fogging, and fixing strength.
[2.1] Uniformity of charging A glass electrode of parallel plate ITO film deposition is immersed in the liquid developer obtained in each of the examples and comparative examples, and the distance between the electrodes is 2.0 mm, the applied voltage is 200 V, and the voltage application time is 10. The toner adhesion amounts m1 and m2 per unit area on both electrode surfaces were measured by electrophoresis under conditions of seconds. The uniformity was evaluated as (m1 / m2) × 100. The larger this value, the more uniform the chargeability.

[2.2] Cover evaluation A mending tape manufactured by Sumitomo 3M Co., Ltd. is affixed to plain paper manufactured by Fuji Xerox Office Supply Co., Ltd. (product name J). The color of this tape was measured with a color difference meter CR-221 manufactured by Minolta Co., Ltd., and this value was used as a reference value.
An image forming apparatus as shown in FIG. 8 was used, and the toner to be evaluated was put in a developing machine, and white (solid white) was printed. Stop the printer during printing, take out the photoconductor, and place the mending tape in the area between the point where the photoconductor and the intermediate transfer roller are in contact (transfer nip) and the point where the developing roller and photoconductor are close (development nip). Affixing and fogging toner were adhered, and this was affixed to J paper. The color difference between this tape and the reference value was measured. Note that the smaller the color difference, the less the fogging.

[2.3] Fixing Strength Using an image forming apparatus as shown in FIG. 8, images of a predetermined pattern using the liquid developer obtained in each of the above examples and each of the comparative examples were printed on a recording paper manufactured by Seiko Epson Corporation. Paper LPCPPA4). Thereafter, the image formed on the recording paper was thermally fixed by an oven. This heat fixing was performed under the condition of 120 ° C. × 30 minutes.

Thereafter, after confirming the non-offset area, the fixed image on the recording paper is erased twice (rubber eraser “LION 261-11” manufactured by Lion Business Machine Co., Ltd.) with a pressing load kgf, and the residual ratio of the image density is X -Measured by "X-Rite model 404" manufactured by Rite Inc, and evaluated according to the following three-stage criteria.
○: Image density residual ratio is 90% or more.
Δ: Image density remaining ratio is 70% or more and less than 90%.
X: Image density residual ratio is less than 70%.
These results are shown in Table 1.

As is clear from Table 1, all of the liquid developers of the present invention (Examples 1 to 4) were excellent in charging uniformity, fogging, and fixing strength. On the other hand, all of the toners of the comparative examples were inferior in charging uniformity, fogging, and fixing strength.
In addition, when the liquid developer obtained in each example and each comparative example was allowed to stand for 6 months at 35 ° C. and a relative humidity of 65%, the liquid developer obtained in each example was precipitated, floated or aggregated. Was not recognized. On the other hand, precipitation, floating or aggregation was confirmed in the liquid developers obtained in the respective comparative examples.

  Moreover, in each Example and each comparative example, as a coloring agent, a copper phthalocyanine pigment, pigment red 57: 1, C.I. I. A liquid developer was prepared in the same manner except that Pigment Yellow 93 and carbon black (Printex L, manufactured by Degussa Co., Ltd.) were encapsulated, and these liquid developers were evaluated in the same manner as described above. went. As a result, the same results as those of the respective Examples and Comparative Examples were obtained.

It is a figure which shows the manufacturing process of the coloring agent applied to the toner of this invention. It is a figure which shows an example of the microencapsulation pigment applied to the toner of this invention. It is a figure which shows the manufacturing process of the coloring agent applied to the toner of this invention. It is a figure which shows an example of the microencapsulation pigment applied to the toner of this invention. FIG. 3 is a longitudinal sectional view schematically showing an example of the configuration of a kneader and a cooler used in the toner production method of the present invention. FIG. 2 is a longitudinal sectional view schematically showing a preferred embodiment of a dry fine particle production apparatus (toner particle production apparatus) used for production of the liquid developer of the present invention. FIG. 7 is an enlarged cross-sectional view of the vicinity of the head portion of the dry particle manufacturing apparatus shown in FIG. 1 is a cross-sectional view illustrating an example of a contact-type image forming apparatus to which a liquid developer of the present invention is applied. 1 is a cross-sectional view illustrating an example of a non-contact type image forming apparatus to which a liquid developer of the present invention is applied. FIG. 3 is a cross-sectional view illustrating an example of a fixing device to which the liquid developer of the present invention is applied. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus.

Explanation of symbols

K1 ... kneading machine K2 ... process part K21 ... barrel K22, K23 ... screw K24 ... fixing member K25 ... deaeration port K3 ... head part K31 ... internal space K32 ... extrusion port K33 ... cross-sectional area gradually decreasing part K4 ... feeder K5 ... raw material K6 ... Cooling machines K61, K62, K63, K64 ... Rolls K611, K621, K631, K641 ... Rotating shaft K65, K66 ... Belt K67 ... Discharge part K7 ... Kneaded material 1 ... Pigment particles 11 ... Anionic group 12 ... Hydrophobic group 13 ... Polymerizable group 14 ... Cationic group 2 ... Anionic polymerizable surfactant 60 ... Polymer layer 100, 101 ... Microencapsulated pigment M1 ... Dry fine particle production apparatus (toner particle production apparatus) M2 ... Head part M21 ... Dispersion Reservoir M22 ... Piezoelectric element M221 ... Lower electrode M222 ... Piezoelectric body M223 ... Upper electrode M DESCRIPTION OF SYMBOLS 3 ... Discharge part M24 ... Diaphragm M25 ... Acoustic lens M26 ... Pressure pulse convergence part M3 ... Dispersion medium removal part M31 ... Housing M311 ... Reduced diameter part M4 ... Aqueous suspension supply part (aqueous dispersion supply part) M41 ... Stirring Means M5 ... Recovery part M6 ... Container M7 ... Gas injection port M8 ... Voltage application means M10 ... Gas flow supply means M101 ... Duct M11 ... Heat exchanger M12 ... Pressure adjusting means M121 ... Connection pipe M122 ... Expanded part M123 ... Filter M13 ... throttle member P ... pump 3 ... aqueous suspension (aqueous dispersion) 31 ... dispersoid 32 ... dispersion medium (aqueous dispersion medium) 4 ... dry fine particles (toner particles) 5 ... insulating liquid 9 ... droplet P1 ... image Forming device P2 ... photoconductor P3 ... charger P4 ... exposure P10 ... developer P11 ... developer container P12 ... coating roller P13 ... developing roller P14 ... liquid developer coating Layer P15 ... Metering blade P16 ... Roller core P17 ... Development roller cleaning blade P18 ... Intermediate transfer roller P19 ... Secondary transfer roller P20 ... Information recording medium P21 ... Static elimination light P22 ... Cleaning blade P23 ... Cleaning blade P24 ... Charging blade F40 Fusing unit F1 Heat fixing roll (heating roll) F1a Columnar halogen lamp F1b Roll base material F1c Elastic body F2 Pressure roller F2a Rotating shaft F2b Roll base material F2c Elastic body F3 Heat-resistant belt F4 Belt tension member F4a ... Projection wall F4f ... Concavity F5 ... Sheet material F5a ... Unfixed toner image F6 ... Cleaning member F9 ... Spring

Claims (15)

A method for producing a liquid developer in which toner particles are dispersed in an insulating liquid,
Preparing a dispersion in which a dispersoid composed of a resin material and a material containing a colorant is dispersed in a dispersion medium;
A step of removing the dispersion medium by spraying the dispersion as droplets to obtain a dry fine particle;
A dispersion step of dispersing the dry fine particles in an insulating liquid,
As the colorant, pigment particles having a cationic group on the surface are coated with a polymer having a repeating structural unit derived from an anionic polymerizable surfactant having an anionic group, a hydrophobic group, and a polymerizable group. A method for producing a liquid developer, wherein   The colorant is obtained by coating the pigment particles with a polymer by polymerizing the anionic polymerizable surfactant in an aqueous dispersion in which the pigment particles having a cationic group on the surface are dispersed. The method for producing a liquid developer according to claim 1.   The method for producing a liquid developer according to claim 1, wherein the polymer further has a repeating structural unit derived from a hydrophobic monomer. The liquid according to any one of claims 1 to 3, wherein the polymer further has a repeating structural unit derived from a crosslinkable monomer and / or a repeating structural unit derived from a monomer represented by the following general formula (1). A method for producing a developer.

  The method for producing a liquid developer according to claim 1, wherein the pigment constituting the pigment particles is carbon black.   The cationic group of the pigment particle is selected from the group consisting of a primary amine cation group, a secondary amine cation group, a tertiary amine cation group, and a quaternary ammonium cation group. 6. A method for producing a liquid developer as described in any one of 5 above. The anionic group of the anionic polymerizable surfactant is a sulfonate anion group (—SO ₃ ^— ), a sulfinate anion group (—RSO ₂ ^— : R is a C _{1 to} C ₁₂ alkyl group or a phenyl group, and The method for producing a liquid developer according to claim 1, which is selected from the group consisting of a modified product) and a carboxylate anion group (—COO ⁻ ).   8. The liquid developer according to claim 1, wherein the hydrophobic group of the anionic polymerizable surfactant is selected from the group consisting of an alkyl group, an aryl group, and a group in which these are combined. Manufacturing method.   The polymerizable group of the anionic polymerizable surfactant is an unsaturated hydrocarbon group capable of radical polymerization, and includes a vinyl group, an allyl group, an acryloyl group, a methacryloyl group, a propenyl group, a vinylidene group, and a vinylene group. 9. The method for producing a liquid developer according to claim 1, wherein the liquid developer is selected from the group.   The colorant is prepared by adding the anionic polymerizable surfactant to the aqueous dispersion of pigment particles having the cationic group on the surface and mixing, and then adding the anionic polymerizable surfactant and emulsifying, followed by polymerization. The method for producing a liquid developer according to any one of claims 1 to 9, which is obtained by adding an agent and polymerizing in water.   The colorant is prepared by adding the anionic polymerizable surfactant to an aqueous dispersion of pigment particles having the cationic group on the surface and mixing, and then adding a hydrophobic monomer and the anionic polymerizable surfactant. The method for producing a liquid developer according to claim 1, which is obtained by mixing, emulsifying, adding a polymerization initiator and polymerizing in water. The colorant is prepared by adding the anionic polymerizable surfactant to an aqueous dispersion of pigment particles having the cationic group on the surface and mixing the mixture, and then mixing the hydrophobic monomer and the crosslinkable monomer and / or the following general formula (1) The monomer represented by the above formula and the anionic polymerizable surfactant are added and mixed, and after emulsification, a polymerization initiator is added, and polymerization is performed in water. A method for producing a liquid developer.

  The method for producing a liquid developer according to claim 1, wherein in the dispersion medium removing step, the droplets are sprayed using a piezoelectric pulse.   A liquid developer produced by the method according to claim 1. The liquid developer according to claim 14, comprising a charge control agent.

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