JP2007114226A - Liquid developer and method for manufacturing the liquid developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid developer that is superior in the charging characteristics of positive charging property, to provide and a method for manufacturing the developer. <P>SOLUTION: The liquid developer has positive charging property and contains toner particles dispersed in an insulating liquid, wherein the toner particles are characterized in that mother particles having an anionic group on the surface are coated with a polymer layer, having a repeating structural unit derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group. The resin material, constituting the mother particles, preferably contains at least either polyester resin or styrene-acrylate copolymer. The acid value of the resin material, constituting the mother particles, is preferably 8 to 50 KOHmg/g. The mother particles, preferably have a -COO- group and/or a -SO<SB>3</SB>- group as the anionic group on the surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As a developer used to develop the electrostatic latent image formed on the latent image carrier, a toner composed of a material containing a colorant such as a pigment and a binder resin is used as an electrically insulating carrier liquid (insulating property). Liquid developers dispersed in (liquid) are known.
Examples of the liquid developer include a negatively chargeable liquid developer and a positively chargeable liquid developer. When a negatively chargeable liquid developer is used, an image is formed inside the image forming apparatus. Ozone is generated, causing problems such as environmental problems and adverse effects on peripheral components in the image forming apparatus.

Therefore, in recent years, since it is possible to perform image formation by reducing the amount of discharge products such as ozone, development of a method for forming an image using a positively chargeable liquid developer has been promoted (for example, Patent Document 1).
In the positively chargeable liquid developer described in Patent Document 1, the toner particles are positively charged by adding a charge control agent.

By the way, as the resin material constituting the toner particles, a negatively chargeable one is generally widely used from the viewpoints of fixability and charging characteristics. When such a negatively chargeable resin material is used, it is difficult to positively charge the toner particles (liquid developer). In addition, it is conceivable to add a charge control agent to toner particles using a negatively chargeable resin material for positive charging, but it is difficult to obtain a sufficient charge amount.
Although it is conceivable to use a positively chargeable resin material as a constituent material of the toner particles, the positively chargeable resin material has low stability of the resin itself and is difficult to apply as a material constituting the toner particles. Met.

JP 10-319646 A

  An object of the present invention is to provide a liquid developer excellent in positive charging characteristics and a method for producing the same.

Such an object is achieved by the present invention described below.
The liquid developer of the present invention is a positively chargeable liquid developer in which toner particles are dispersed in an insulating liquid,
The toner particles are coated with a polymer layer having a repeating structural unit derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group, and a polymerizable group on a mother particle having an anionic group on the surface. It is characterized by being made.
As a result, the charge on the surface of the mother particle is canceled by the cationic group derived from the cationic polymerizable surfactant, and the cationic group derived from the cationic polymerizable surfactant is present on the toner particle surface. Therefore, a liquid developer having excellent positive charging characteristics can be obtained.

In the liquid developer of the present invention, it is preferable that the resin material constituting the mother particle contains at least one of a polyester resin and a styrene-acrylic acid ester copolymer.
Since these resin materials are generally highly negatively charged resins, it has been difficult to apply them to toner particles constituting a positively chargeable liquid developer. As a constituent material of toner particles constituting a positively chargeable liquid developer, even a highly negatively chargeable material is coated with a polymer layer having a repeating structural unit derived from a surfactant. can do.

In the liquid developer of the present invention, the acid value of the resin material constituting the mother particle is preferably 8 to 50 KOHmg / g.
When the acid value of the resin material constituting the mother particles is in such a range, a polymer layer can be suitably formed on the surface of the mother particles, and as a result, the charging characteristics of the liquid developer can be effectively improved. Can be improved. In addition, since the polymer layer can be formed firmly, unintentional dropping of the polymer layer can be effectively prevented.

In the liquid developer of the present invention, the base particles, on the surface, as the anionic group, -COO ^- group, -SO ₃ ^- of the group, it preferably has at least one.
The mother particles having such a group have a high affinity with the polymer layer, and can improve the durability of the toner particles. Further, the production is relatively easy and can be obtained at a relatively low cost, and as a result, the cost of producing the liquid developer can be further reduced.

The method for producing the liquid developer of the present invention includes:
Obtaining the mother particles having the anionic group on the surface;
A polymer layer forming step of coating the mother particle with a polymer layer by polymerizing the cationic polymerizable surfactant in the vicinity of the surface of the mother particle having the anionic group on the surface. To do.
Thereby, it is possible to easily provide a liquid developer excellent in positive charging characteristics.

In the method for producing a liquid developer of the present invention, the polymer layer forming step is preferably performed in an aqueous dispersion in which the mother particles having the anionic group on the surface are dispersed.
Thereby, it is possible to more easily provide a liquid developer excellent in positive charging characteristics.
In the method for producing a liquid developer of the present invention, in the polymer layer forming step, it is preferable to add the cationic polymerizable surfactant to the aqueous dispersion and mix, and then add a polymerization initiator to perform emulsion polymerization. .
Thereby, it is possible to more easily provide a liquid developer excellent in positive charging characteristics.

In the method for producing a liquid developer of the present invention, in the polymer layer forming step, the cationic polymerizable surfactant is added to and mixed with the aqueous dispersion, and then the hydrophobic monomer and the cationic polymerizable surfactant are added. In addition, it is preferably obtained by emulsion polymerization after adding a polymerization initiator after emulsification.
Thereby, unintentional peeling of the polymer layer covering the mother particles can be effectively prevented, and the durability of the toner particles can be improved.

In the method for producing a liquid developer of the present invention, in the polymer layer forming step, the cationic dispersion surfactant is added to the aqueous dispersion and mixed, and then subjected to treatment by irradiating with ultrasonic waves.
Adding a hydrophobic monomer and mixing;
Adding and mixing the cationic polymerizable surfactant and irradiating with ultrasonic waves;
It is preferable to sequentially perform the step of emulsion polymerization by adding a polymerization initiator.
Thereby, unintentional peeling of the polymer layer covering the mother particles can be effectively prevented, and the durability of the toner particles can be improved.

これにより、母粒子を被覆するポリマー層の不本意な剥がれ等を効果的に防止することができ、トナー粒子の耐久性を向上させることができる。 In the method for producing a liquid developer of the present invention, in the polymer layer forming step, the cationic dispersion surfactant is added to the aqueous dispersion and mixed, and then subjected to treatment by irradiating with ultrasonic waves.
Adding and mixing a hydrophobic monomer and a crosslinkable monomer and / or a monomer represented by the following general formula (1);
A step of adding a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group, mixing and irradiating with ultrasonic waves, and
It is preferable to sequentially perform the step of emulsion polymerization by adding a polymerization initiator.

Thereby, unintentional peeling of the polymer layer covering the mother particles can be effectively prevented, and the durability of the toner particles can be improved.

Hereinafter, preferred embodiments of the liquid developer of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a view showing an example of toner particles constituting the liquid developer of the present invention.
The liquid developer of the present invention is one in which toner particles are dispersed in an insulating liquid.
<Insulating liquid>
First, the insulating liquid will be described.
The insulating liquid used in the present invention may be a liquid having a sufficiently high insulating property. Specifically, it is preferable that the electric resistance at room temperature (20 ° C.) is 10 ⁹ Ωcm or more. ^It is more preferably ¹¹ Ωcm or more, and even more preferably 10 ¹³ Ωcm or more.
The dielectric constant of the insulating liquid is preferably 3.5 or less.

  Examples of the insulating liquid that satisfies such conditions include octane, isooctane, decane, isodecane, decalin, nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, various silicone oils, Vegetable oil such as linseed oil, soybean oil, Isopar E, Isopar G, Isopar H, Isopar L (Isopar; trade name of Exxon), Cielsol 70, Cielsol 71 (Cielsol; trade name of Ciel Oil), Amsco OMS, Amsco 460 solvent (Amsco; trade name of Spirits), liquid paraffin (Wako Pure Chemical Industries) and the like.

<Toner particles>
The toner particles constituting the liquid developer according to the present invention are such that the mother particles having an anionic group on the surface are derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group. It is coated with a polymer layer having a structural unit.
As shown in FIG. 1, the toner particle 100 has an anionic group 14 on the surface of the mother particle 1 and a cationic group 11 of a polymer layer 60 derived from a cationic polymerizable surfactant as described later. In the ionically bonded state, the mother particle 1 is covered with the polymer layer 60, and has a cationic group 11 ′ derived from a cationic polymerizable surfactant on the surface of the polymer layer 60. .

  By the way, as the resin material constituting the toner particles, a negatively chargeable one is generally widely used from the viewpoints of fixability and charging characteristics. When such a negatively chargeable resin material is used, it is difficult to positively charge the toner particles (liquid developer). In addition, it is conceivable to add a charge control agent to toner particles using a negatively chargeable resin material for positive charging, but it has been difficult to obtain a sufficient charge amount.

Although it is conceivable to use a positively chargeable resin material as a constituent material of the toner particles, the positively chargeable resin material has low stability of the resin itself and is difficult to apply as a material constituting the toner particles. Met.
On the other hand, by using toner particles in which mother particles having an anionic group on the surface are coated with a polymer layer derived from a cationic polymerizable surfactant, the charge on the surface of the mother particles is changed to a cation. It is countered by the cationic group derived from the polymerizable polymerizable surfactant and the cationic group derived from the cationic polymerizable surfactant is present on the surface of the toner particles, so that it has excellent positive charging characteristics. Liquid developer.

  Further, the toner particles constituting the conventional liquid developer generally require heating at a relatively high temperature in order to be fixed on the recording medium. By coating with a polymer layer derived from a cationic polymerizable surfactant, high fixing strength can be obtained even when fixing at a relatively low temperature. This is because the polymer layer derived from the cationic polymerizable surfactant has a high affinity with a recording medium such as paper, and therefore the polymer layer is not fixed even at a relatively low temperature. This is considered to be because it adheres firmly to the recording medium.

In addition, the mother particles are not simply covered with the polymer layer, but the mother particles and the polymer layer are electrically strongly bonded, so that the polymer layer may be unintentionally peeled off from the pigment surface. Therefore, it is possible to prevent the deterioration of charging characteristics with certainty.
Further, by coating the mother particles with the polymer layer, the average particle diameter of the toner particles can be made appropriate.

The average particle size of such toner particles is preferably from 0.1 to 5 μm, more preferably from 0.4 to 4 μm, and even more preferably from 0.5 to 3 μm. 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 2.0 μm, and 0.1 to 1. More preferably, it is 0 μm. 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.

<Polymer layer 60>
The polymer layer 60 is composed of a polymer layer derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group, and a polymerizable group.
The cationic group of the cationic polymerizable surfactant is preferably a cationic group selected from the group consisting of a primary amine cation, a secondary amine cation, a tertiary amine cation, and a quaternary ammonium cation. The primary amine cation is a monoalkylammonium cation (RNH ₃ ⁺ ) or the like, the secondary amine cation is a dialkylammonium cation (R ₂ NH ₂ ⁺ ) or the like, and the tertiary amine cation is a trialkylammonium cation (R _3). NH ⁺ ) and the like, and examples of the quaternary ammonium cation include (R ₄ N ⁺ ) and the like. Here, R is a hydrophobic group and a polymerizable group, and examples thereof include those shown below.

Examples of the counter anion of the above-described cationic group include Cl ⁻ , Br ⁻ and I ⁻ .
The hydrophobic group is preferably selected from the group consisting of an alkyl group, an aryl group, and a group in which these are combined.
The polymerizable group is preferably an unsaturated hydrocarbon group, and more specifically 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. preferable. Among these, an acryloyl group and a methacryloyl group can be exemplified as preferable examples.
Specific examples of the cationic polymerizable surfactant include a cationic allylic acid derivative as described in JP-B-4-65824.

Examples of the cationic polymerizable surfactant used in the present invention include compounds represented by the general formula R _{[4- (l + m + n)]} R ¹ _l R ² _m R ³ _n N ⁺ · X ^−. (R is a polymerizable group, R ¹ , R ² , and R ³ are each an alkyl group or an aryl group, X is Cl, Br, or I, and l, m, and n are each 1 or 0. .) Here, as the polymerizable group, a hydrocarbon group having an unsaturated hydrocarbon group capable of radical polymerization can be preferably exemplified, and more specifically, an allyl group, an acroyl group, a methacryloyl group, a vinyl group, a propylene group, and a propylene group. Nyl group, vinylidene group, vinylene group and the like can be mentioned.

  Specific examples of the cationic polymerizable surfactant include dimethylaminoethyl methyl chloride methacrylate, dimethylaminoethyl benzyl methacrylate methacrylate, methacryloyloxyethyltrimethylammonium chloride, diallyldimethylammonium chloride, 2-hydroxy-3-methacryloxypropyl. Examples thereof include trimethylammonium chloride.

A commercial item can also be used as said cationic polymerizable surfactant. Examples include Acryester DMC (Mitsubishi Rayon Co., Ltd.), Acryester DML60 (Mitsubishi Rayon Co., Ltd.), C-1615 (Daiichi Kogyo Seiyaku Co., Ltd.), and the like.
The cationic 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 a cationic 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.

<Base particle 1>
The mother particles constituting the toner particles in the liquid developer of the present invention have an anionic group on the surface.
Hereinafter, the material which comprises the mother particle 1 is demonstrated.

1. Resin material (binder resin)
The mother particle 1 is mainly composed of a resin material.
In general, the functional group present on the surface of the mother particle is derived from the functional group of the resin material constituting the mother particle.
Therefore, it is preferable to use a resin material having an anionic group as the resin material constituting the mother particle 1. Thereby, an anionic group can exist reliably on the surface of the mother particle 1.

Examples of the anionic group, e.g., -COO ^- _group, ^-SO 3 -, -CO group, -OH group, -OSO ₃ ^- group, -COO- group, -SO ₃ - group, -OSO ₃ - group, - Examples include PO ₃ H ₂ , —PO ₄ ^— group, quaternary ammonium, and salts thereof.
Among the groups described above, in particular, -COO ^- group, -SO ₃ ^- group. Such a group has a high affinity with the polymer layer 60 and can effectively prevent the polymer layer 60 from being unintentionally peeled off. In addition, the resin material having such a group is relatively easy to manufacture and can be obtained relatively inexpensively. As a result, the cost of manufacturing the liquid developer can be further reduced.

The groups as described above are preferably present in the side chain of the polymer constituting the resin material. Thereby, an anionic group can be made to exist more reliably on the surface of the mother particle 1. In addition, anionic groups can be uniformly present on the surface of the mother particle 1, and as a result, the surface of the mother particle 1 can be uniformly coated with the polymer layer 60.
Examples of the resin material having an anionic group as described above include a resin material (raw material resin) or a monomer (monomer), a dimer (dimer), an oligomer, and the like, which will be described later. It can be produced by bonding a material having a functional group.

For example, -COO ^- resin material having a group, sparingly water-soluble or water-insoluble resin (raw material resin) to the unsaturated carboxylic acids can be polymerized graft copolymerization or block copolymerization, or a monomer constituting the thermoplastic resin And unsaturated carboxylic acids can be produced by random copolymerization.
Examples of unsaturated carboxylic acids include (meth) acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid, maleic anhydride, citraconic anhydride and the like. Saturated monocarboxylic acids or dicarboxylic acids or anhydrides thereof, monoesters of unsaturated carboxylic acids such as methyl, ethyl and propyl, esterified products such as diesters, alkali metal salts, alkaline earth metal salts, ammonium salts, etc. Unsaturated carboxylates and the like can be used.

Further, for example, a resin material having a —SO ₃ ^— group may be obtained by graft copolymerization or block copolymerization of an unsaturated sulfonic acid with a thermoplastic resin (raw material resin), or an unsaturated monomer constituting an addition polymerizable thermoplastic resin. Random copolymerization of monomers and monomers containing unsaturated sulfonic acids, or polycondensation of monomers constituting the polycondensation thermoplastic resin and monomers containing unsaturated sulfonic acids By making it, it can manufacture.

  As unsaturated sulfonic acids, for example, styrene sulfonic acids, sulfoalkyl (meth) acrylates, or metal salts, ammonium salts thereof, and the like can be used. Moreover, as a monomer containing sulfonic acids, sulfoisophthalic acids, sulfoterephthalic acids, sulfophthalic acids, sulfosuccinic acids, sulfobenzoic acids, sulfosalicylic acids, or a metal salt or ammonium salt thereof can be used.

  Examples of the raw material resin (raw resin) include (meth) acrylic resin, polycarbonate resin, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene -Styrene resin such as acrylic ester-methacrylic ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic ester copolymer, styrene-vinyl methyl ether copolymer Or a simple substance containing a styrene substitution product Polymer 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 acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, and the like. They can be used in combination.

Among the above-mentioned, since the polyester resin has high transparency, when the polyester resin is used, the color developability of the obtained image can be made higher.
Further, when the styrene-acrylic acid ester copolymer is used, the fixing property of the toner particles at a low temperature can be further improved.
As described above, polyester resin and styrene-acrylic acid ester copolymer have excellent properties as a resin, but since they are generally negatively chargeable resins, they constitute positively chargeable liquid developers. It was difficult to apply to toner particles. However, as in the present invention, by covering with a polymer layer having a repeating structural unit derived from a cationic polymerizable surfactant as described above, even a negatively chargeable material as described above, It can be suitably applied as a constituent material of toner particles constituting a positively chargeable liquid developer.

The resin material having an anionic group is, for example, polymerizing a precursor having a functional group as described above (for example, a corresponding monomer (monomer), dimer (dimer), oligomer, etc.). Can also be manufactured.
The number of anionic groups contained in the resin material is preferably 0.005 to 0.5 mol, and more preferably 0.01 to 0.1 mol, relative to 100 g of the resin material. Thereby, the number of anionic groups present on the surface of the mother particle 1 can be made suitable, and the surface of the mother particle 1 can be more reliably covered with the polymer layer 60.

  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.

  The acid value of the resin material is not particularly limited, but is preferably 8 to 50 KOH mg / g, more preferably 9 to 40 KOH mg / g, and still more preferably 10 to 38 KOH mg / g. If the acid value of the resin material constituting the mother particles is in such a range, the polymer layer can be firmly formed, and therefore the polymer layer can be effectively prevented from unintentionally falling off. . Further, in the method described later, a polymer layer can be suitably formed on the surface of the mother particle, and as a result, the charging characteristics of the liquid developer can be effectively improved. On the other hand, if the acid value of the resin material is less than the lower limit, the coating with the polymer layer may be insufficient depending on the type of anionic group, the type of the resin material, and the like. May become unstable, and problems such as a decrease in image density and an increase in fog may occur. On the other hand, when the acid value of the resin material exceeds the above upper limit, the amount of anionic groups is increased more than necessary, and the electric resistance may become unstable. Further, the dispersibility of the toner particles in the insulating liquid may be reduced.

The resin material may include a resin material other than the resin having an anionic group as described above. As such a resin material (resin material other than the resin having an anionic group), for example, those exemplified above as the raw material resin can be used.
In the above description, the anionic group has been described as being introduced by processing the resin material. However, for example, the anionic group may be originally contained in the resin material, or resin It may be introduced by forming a particle with a material or the like and then subjecting the particle to a surface treatment. The latter will be described in detail later.

2. Colorant The mother particles may contain a colorant in addition to the resin material described above. Examples of the colorant that can be used include pigments and dyes. Examples of such pigments and dyes include carbon black, spirit black, lamp black (CI No. 77266), magnetite, titanium black, chrome lead, cadmium yellow, mineral fast yellow, navel yellow, and naphthol yellow S. , Hansa Yellow G, Permanent Yellow NCG, Chrome Yellow, Benzidine Yellow, Quinoline Yellow, Tartrazine Lake, Red Mouth Lead, Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Permanent Red 4R, Watching Red Calcium salt, eosin lake, brilliant carmine 3B, manganese purple, fast violet B, methyl violet lake, bitumen, cobalt blue, al Reblue Lake, Victoria Blue Lake, First Sky Blue, Indanthrene Blue BC, Ultramarine, Aniline Blue, Phthalocyanine Blue, Calco Oil Blue, Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake, Phthalocyanine Green, Final Yellow Green G, Rhodamine 6G, quinacridone, rose bengal (C.I. No. 45432), C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 5: 1, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Basic Green 6, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 162, nigrosine dye (CI No. 50415B), metal complex dye, silica, aluminum oxide, magnetite, maghemite, various ferrites, cupric oxide, nickel oxide, zinc oxide, zirconium oxide, titanium oxide, Examples thereof include metal oxides such as magnesium oxide, and magnetic materials containing magnetic metals such as Fe, Co, and Ni, and one or more of these can be used in combination.

3. Other components Moreover, the mother particles 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 mother particles 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 toner particles (base particles) or in an 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.
FIG. 2 is a longitudinal sectional view schematically showing an example of the configuration of a kneader and a cooler for producing a kneaded product.
In the following description, a case where a liquid developer is produced using a kneaded material K7 containing a colorant and a resin material will be described. In the following description, a case where a resin material having an anionic group is used will be described.
The kneaded material K7 can be manufactured using, for example, an apparatus as shown in FIG.

[Kneading process]
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, air contained in the raw material K5 ( In particular, air entrained by the colorant can be efficiently removed, and bubbles can be effectively prevented from being mixed (residual) 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 | mixing 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 step, 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 step 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 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 (kneaded solution))
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), polymer layer rain 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) Examples thereof include anionic organic dispersants such as sodium salts and the like, and cationic organic dispersants such as quaternary ammonium salts (for example, dodecyltrimethylammonium chloride and the like). 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 5.0 μm, and more preferably 0.05 to 4.0 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 benzoic acid metal salts, salicylic acid metal salts, alkyl salicylic acid metal salts, catechol metal salts, metal-containing bisazo dyes, nigrosine dyes, tetraphenylborate derivatives, quaternary ammonium salts, 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]
In the present embodiment, a solid dispersoid (the mother particle 1 having an anionic group 14 on the surface) is dispersed in the aqueous dispersion medium 32 from the aqueous emulsion in which the liquid dispersoid is dispersed in the aqueous dispersion medium. The aqueous suspension is obtained, and the polymer layer 60 is formed on the surface of the mother particle 1 using the aqueous suspension.
Hereinafter, a method for preparing the aqueous suspension will be described in detail.
The aqueous suspension 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, an aqueous suspension with particularly small variation in the size and shape of the dispersoid 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 gas in the aqueous suspension can be reduced, and when the dispersion medium 32 is removed from the droplets 9 of the dispersion 3 in the dispersion medium removal unit M3 of the toner particle manufacturing apparatus M1 described later. In addition, it is possible to effectively prevent bubbles and the like from being generated in the dispersion liquid 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 irregularly shaped toner particles 100 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 irregularly shaped dispersoids is sufficiently prevented (the solvent is rapidly vaporized (boiling) from within the dispersoids of the aqueous emulsion). The solvent can be removed quickly while reliably preventing this).

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 diameter of the dispersoid (base particle 1 having anionic group 14 on the surface) in the aqueous suspension is not particularly limited, but is preferably 0.01 to 5 μm, and 0.05 to 4 μm. Is more preferable. Thereby, the unintentional coupling | bonding (aggregation) of dispersoids can be prevented more reliably.

  In the above description, the case where an anionic group is introduced onto the surface of the mother particle by using a resin material having an anionic group has been described. For example, a resin material having no anionic group is used. An anionic group may be introduced by preparing an aqueous suspension and subjecting the formed mother particles to a surface treatment. In this case, for example, the following surface treatment agent can be used.

Preferred examples of the anionic group-imparting agent for treating the surface of the mother particles include a sulfur-containing treatment agent.
Examples of the treatment agent containing sulfur include sulfuric acid, fuming sulfuric acid, sulfur trioxide, chlorosulfuric acid, fluorosulfuric acid, amidosulfuric acid, sulfonated pyridine salt, and sulfamic acid. Among them, sulfur trioxide, sulfonated pyridine salt, or sulfamine. Sulfonating agents such as acids are preferred. These can be used individually or in mixture of 2 or more types.

In addition, a solvent capable of forming a complex with the sulfur trioxide (a basic solvent such as N, N-dimethylformamide dioxane, pyridine, triethylamine, and trimethylamine, nitromethane, acetonitrile, etc.) and a solvent described later. It is also useful to form a complex with a mixed solvent of one or more kinds.
In particular, if sulfur trioxide itself is too reactive to decompose or alter the resin itself, or it is difficult to control the reaction with a strong acid, a complex of sulfur trioxide and a tertiary amine is used as described above. It is preferable to use the surface treatment of the mother particles.
In addition, when sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, etc. are used alone, the mother particles easily dissolve, and it is necessary to suppress the reaction for strong acids that react per molecule. It is necessary to pay attention to the type of solvent and the amount used.

  The solvent used in the reaction is selected from those which do not react with the treatment agent containing sulfur and in which the above-mentioned pigment becomes insoluble or hardly soluble, and sulfolane, N-methyl-2-pyrrolidone, dimethylacetamide, Examples include quinoline, hexamethylphosphoric triamide, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, dichloromethane, nitromethane, nitrobenzene, liquid sulfur dioxide, carbon disulfide, and trichlorofluoromethane.

The treatment with the treatment agent containing sulfur is performed by dispersing the mother particles in a solvent, adding the treatment agent containing sulfur to the dispersion, heating to 60 to 200 ° C., and stirring for 3 to 10 hours. At this time, the determination of the amount of the anionic group introduced largely depends on the reaction conditions and the type of the treatment agent containing sulfur. After this heat treatment, the processing agent containing the solvent and residual sulfur is removed from the slurry of the base particles. Removal is carried out by repeatedly washing with water, ultrafiltration, reverse osmosis, etc., centrifugation, filtration and the like.
Furthermore, by treating the sulfonic acid (—SO ₃ H) described above with an alkali compound, mother particles having a sulfonic acid anion group (—SO ₃ ^— ) on the surface can be obtained.

As the alkali compound, a cation is an alkali metal ion or a chemical formula (R ₁ R ₂ R ₃ R ₄ N) ⁺ (R ₁ , R ₂ , R ₃ and R ₄ may be the same or different, and a hydrogen atom, an alkyl group, An alkaline compound that is a monovalent ion represented by (showing a hydroxyalkyl group or an alkyl halide group) is selected. Preferably, an alkaline compound in which the cation is an alkanolamine cation such as lithium ion (Li ⁺ ), potassium ion (K ⁺ ), sodium ion (Na ⁺ ), ammonium ion (NH 4 ⁺ ), and triethanolamine cation. is there.

  Hydroxyl anion is preferably used as the anion of the alkali compound. Specific examples thereof include ammonia, alkanolamine (monoethanolamine, diethanolamine, N, N-butylethanolamine, triethanolamine, propanolamine, aminomethyl). Propanol, 2-aminoisopropanol, etc.) and monovalent alkali metal hydroxides (LiOH, NaOH, KOH).

The amount of the alkali compound added is preferably at least the neutralization equivalent of the sulfonic acid group of the mother particle. Further, for volatile additives such as ammonia and alkanolamine, addition of 1.5 times or more of the neutralization equivalent is generally preferable.
In addition, operation can be performed by putting the mother particle in which the sulfonic acid group is chemically bonded to the surface in an alkali compound and shaking with a paint shaker or the like.

Moreover, a carboxylating agent can also be mentioned suitably as an anionic group provision agent for processing the surface of a mother particle.
As a carboxylating agent, an oxidant such as hypohalite such as sodium hypochlorite or potassium hypochlorite is used to cut a partial bond (C = C, CC) on the surface of the mother particle. And by oxidizing.

As an example of the treatment with the carboxylating agent, the mother particles are dispersed in advance in an aqueous medium to obtain a dispersion. Next, a hypohalite such as sodium hypochlorite having an effective halogen concentration of 10 to 30% is mixed in an appropriate amount of water and heated to 60 to 80 ° C. for about 5 to 10 hours, preferably 10 It is performed by stirring for more than an hour. This operation involves a considerable amount of heat and requires safety precautions. Thereafter, the solvent and the remaining carboxylating agent are removed from the slurry of the surface-treated mother particles by heat treatment. If necessary, water washing, ultrafiltration, reverse osmosis, etc., centrifugation, filtration, etc. are repeated.
Then, by treating the mother particles having a carboxylic acid group (-COOH) with an alkaline compound, a carboxylic acid anion group - it can be a mother particle having a surface ^(-COO).
The kind of alkali compound and the treatment method with the alkali compound are the same as described above.

[Formation Step of Polymer Layer 60 (Formation Step of Toner Particle 100)]
Next, the polymer layer 60 is formed on the surface of the mother particles (mother particles having an anionic group on the surface) 1 contained in the aqueous suspension obtained as described above. That is, the dispersion liquid 3 in which the toner particles 100 are dispersed in the aqueous dispersion medium 32 is obtained.
FIG. 3 is a diagram showing an example of a process for forming a polymer layer on the surface of the mother particle, FIG. 4 is a diagram showing another example of a process for forming the polymer layer on the surface of the mother particle, and FIG. 5 is a liquid of the present invention. It is a figure which shows another example of the toner particle which comprises a developing agent.
The polymer layer 60 is prepared by adding a cationic polymerizable surfactant to an aqueous suspension of the mother particle 1 having an anionic group 14 on the surface and mixing, then adding a cationic polymerizable surfactant and emulsifying, and then a polymerization initiator. Can be suitably formed by emulsion polymerization.

Hereinafter, in the formation process of the polymer layer 60, it demonstrates, mentioning the dispersion | distribution state which a mother particle may occur. However, the following dispersed state of the mother particles includes estimation.
First, the possible dispersion state of the mother particles will be described with reference to FIG. The cationic group 11 of the cationic polymerizable surfactant 2 having a cationic group 11, a hydrophobic group 12, and a polymerizable group 13 is formed on the mother particle 1 having an anionic group 14 on the surface in an aqueous suspension. Cationic polymerizable interface which is arranged to face the anionic group 14 of the mother particle 1 and adsorbs with a strong ionic bond, and further has a cationic group 11 ′, a hydrophobic group 12 ′ and a polymerizable group 13 ′. The hydrophobic group 12 ′ and the polymerizable group 13 ′ of the activator 2 ′ are adsorbed by the hydrophobic interaction between the hydrophobic group 12 and the polymerizable group 13 of the cationic polymerizable surfactant 2, and the cationic polymerizable interface The cationic group 11 ′ of the activator 2 ′ is arranged so as to face the direction in which the aqueous dispersion medium exists (water phase side), that is, the direction away from the mother particle 1.

In this state, for example, by adding a polymerization initiator, the polymerizable groups 13 of the adjacent cationic polymerizable surfactants 2 are polymerized to form the mother particles 1 as shown in FIG. Can be coated.
According to such an emulsion polymerization method, the anionic group on the surface of the mother particle having an anionic group on the surface and the cationic group of the cationic polymerizable surfactant are ionically bonded in the polymerization system. In addition, since the polymer layer phase is formed by the polymerization reaction, the arrangement form of the monomer existing around the mother particle before the emulsion polymerization affects the polarization state of the particle surface after the polymerization, and thus is controlled with extremely high accuracy. be able to.

More specifically, the polymer layer 60 is suitably formed by the following procedure.
(1) First, a cationic polymerizable surfactant is added to an aqueous suspension in which mother particles having an anionic group on the surface are dispersed. A part of the added cationic polymerizable surfactant is adsorbed on the anionic group of the “mother particle having an anionic group on the surface” and is ionically bound to be immobilized.

  When the cationic polymerizable surfactant is added to the aqueous suspension of mother particles having an anionic group on the surface, the amount of the cationic polymerizable surfactant added is the amount of the surface of the mother particles in the aqueous suspension. The range of 0.5-2 times mol is preferable with respect to the total number of moles of an anionic group, More preferably, it is the range of 0.8-1.2 times mol. By setting the addition amount to 0.5 times mol or more, the polymer layer can be easily formed by strongly ionically binding to the mother particle having an anionic group. By setting the addition amount to 2 times mol or less, the generation of the cationic polymerizable surfactant not adsorbed on the mother particles can be reduced.

(2) Next, a polymerization initiator is added and 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 suspension to a predetermined polymerization temperature. 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.

As described above, a dispersion 3 is obtained in which particles (toner particles) in which the surfaces of the mother particles are completely covered with the polymer layer are dispersed.
Other comonomer may be added for the purpose of improving the toner particle fixing property and storage stability.
Further, in the polymerization, if necessary, a cationic polymerizable surfactant and a hydrophobic monomer may be present in the aqueous suspension. In this case, the polymer layer is a cationic polymerizable interface. It becomes a copolymer layer copolymerized from the activator and the hydrophobic monomer. In other words, the toner particle has a repeating structural unit in which the mother particle having an anionic group on the surface thereof is derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group and a hydrophobic monomer. It is covered with a polymer layer (copolymer layer) having

  In such toner particles, the cationic polymerizable surfactant is added to the aqueous suspension of the mother particles having the anionic group on the surface and mixed, and then the hydrophobic monomer and the cationic polymerizable surfactant are added. It can manufacture suitably by adding a polymerization initiator after emulsification and carrying out emulsion polymerization. Thereby, toner particles with higher durability can be produced. Thereby, unintentional peeling of the polymer layer covering the mother particles can be effectively prevented.

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. 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 15 to 200 parts by weight with respect to 100 parts by weight of the base particles. Part range. The addition amount of the cationic polymerizable surfactant that forms the outermost contour of the polymer layer is preferably in the range of about 0.5 to 5 times mol of the cationic polymerizable surfactant added first, more preferably 1 to 1. The range is about 2 mol. By setting it in the range of 1 mol or more, the dispersibility and dispersion stability of the toner particles are excellent. Generation of a cationic polymerizable surfactant that does not contribute to the formation of the polymer layer can be suppressed by adjusting the addition amount to 2 times mol or less.
Moreover, it is also preferable that the polymer layer which coat | covers a base particle has a repeating structural unit induced | guided | derived from the crosslinkable monomer.
By having a repeating structural unit derived from a crosslinkable monomer, a crosslinked structure is formed in the polymer layer, and the durability of the polymer layer 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 layer which coat | covers a base particle has a repeating structural unit induced | guided | derived from the monomer further 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 layer, reduces the flexibility of molecules in the polymer layer, that is, restricts the mobility of the molecules. Therefore, the mechanical strength and heat resistance of the polymer layer 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, the polymer layer having a repeating structural unit derived from a crosslinkable monomer and the polymer layer having a repeating structural unit derived from the monomer represented by the general formula (1) have high Tg and mechanical strength. There is an advantage of excellent durability such as heat resistance and solvent resistance.
Moreover, the following are mentioned as a specific example of the monomer represented by the said General formula (1).

The following hydrophilic monomers can be used together with the cationic polymerizable surfactant. Examples of such hydrophilic monomers include those having a hydroxyl group, an ethylene oxide group, an amide group, or an amino group as a hydrophilic group.
Examples of the hydrophilic monomer include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 2-hydroxybutyl methacrylate having an OH group, ethyldiethylene glycol acrylate having an ethylene oxide group, polyethylene glycol monomethacrylate, methoxypolyethylene glycol methacrylate, and the like. N-methylaminoethyl methacrylate, N-methylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl methacrylate, amino group-containing N-methylaminoethyl methacrylate, N-N-dimethylacrylamide, etc. Alkylamino esters of acrylic acid or methacrylic acid such as N- (2-dimethylaminoethyl) acrylamide, N- (2-dimethylaminoethyl) methacrylamide, N, N-dimethylaminopropylacrylamide, and other unsaturated amides having an alkylamino group, and vinylpyridine Examples thereof include vinyl ethers having an alkylamino group such as monovinyl pyridines and dimethylaminoethyl vinyl ether; vinyl imidazole and the like, N-vinyl-2-pyrrolidone, and the like.

  The polymer layer is formed by adding the cationic polymerizable surfactant to an aqueous suspension of mother particles having an anionic group on the surface, and adding water or water and an aqueous solvent as necessary. Then, after irradiation with ultrasonic waves for a predetermined time, the cationic polymerization surfactant and / or the hydrophilic monomer (in addition to these, the above-mentioned hydrophobic monomer, crosslinkable monomer, general formula (1)) Monomers can also be added.) And water is added if necessary, and again irradiated with ultrasonic waves for a predetermined time to disperse, and at a predetermined temperature (temperature at which the polymerization initiator is activated) while performing ultrasonic irradiation and stirring. ), The polymerization initiator is added to activate the polymerization initiator, and emulsion polymerization is performed suitably.

  In the case of using the hydrophobic monomer, more specifically, cationic polymerization having a cationic group, a hydrophobic group, and a polymerizable group in an aqueous suspension of the mother particle having the anionic group on the surface. A cationic polymerizable interface having a cationic 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 a cationic group It comprises a step of adding and mixing an activator and / or a hydrophilic monomer and irradiating with ultrasonic waves, and a step of emulsion polymerization by adding a polymerization initiator. be able to.

  When the crosslinkable monomer and / or the monomer represented by the general formula (1) is used, more specifically, the aqueous suspension of the mother particle having the anionic group on the surface is cationic. A step of adding a cationic polymerizable surfactant having a group, 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 cationic polymerizable surfactant and / or the hydrophilic monomer and irradiating with ultrasonic waves, and a step of emulsion polymerization by adding a polymerization initiator And can be more suitably manufactured by carrying out in the order of the steps.

  Further, when the crosslinkable monomer and / or the monomer represented by the general formula (1) is used, more specifically, the aqueous suspension of the mother particles having the anionic group on the surface is cationic. A step of adding a cationic polymerizable surfactant having a group, a hydrophobic group, and a polymerizable group, mixing and irradiating with ultrasonic waves, a crosslinkable monomer and / or the general formula (1). Adding a monomer having a long-chain alkyl group and mixing, a step of adding a cationic polymerizable surfactant and / or the hydrophilic monomer, mixing and irradiating with ultrasonic waves, and initiation of polymerization It comprises a step of emulsion polymerization by adding an agent, and can be more suitably manufactured by carrying out in the order of the steps.

  As described above, first, the cationic polymerizable surfactant is adsorbed on the anionic group on the surface of the mother particle having an anionic group on the surface, then a hydrophobic monomer is added, and the cationic polymerizable surfactant and / or Alternatively, by adding a hydrophilic monomer and irradiating with ultrasonic waves, the arrangement of the polymerizable surfactant and monomer existing around the mother particle is extremely highly controlled. Then, by the emulsion polymerization, the monomer is converted into the polymer layer in this highly controlled form to form the polymer layer. Thereby, the production | generation of the water-soluble oligomer and polymer layer which are a by-product can be reduced.

The reaction preferably uses a reaction vessel equipped with an ultrasonic generator, a stirrer, a reflux condenser, a dropping funnel and a temperature controller.
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 activation of the polymerization initiator can be preferably carried out by raising the temperature of the aqueous suspension to a predetermined polymerization temperature. 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. When the mother particles having an anionic group as a hydrophilic group on the surface are not in the state of an aqueous suspension, as a pretreatment, dispersion 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 the treatment.

Next, another dispersion state in which mother particles may occur in the polymer layer forming step described above will be described with reference to FIG. The cationic group 11 of the cationic polymerizable surfactant 2 having a cationic group 11, a hydrophobic group 12, and a polymerizable group 13 is added to the mother particle 1 having an anionic group 14 on the surface as a hydrophilic group. It arrange | positions so that it may face 1 anionic group 14, and it adsorb | sucks by a strong ionic bond. The surface of the mother particle 1 has an anionic group 14 chemically bonded at a specific density, and has a hydrophobic region 50 between the anionic groups 14, and a cationic polymerizable interface is formed in the hydrophobic region 50. The hydrophobic group 12 and the polymerizable group 13 of the activator 2 face each other, and the cationic group 11 of this cationic polymerizable surfactant 2 is arranged with the cationic group of another cationic polymerizable surfactant 2. Is done. And the cationic polymerizable surfactant which has the cationic group 11 ', the hydrophobic group 12', and the polymerizable group 13 'in the hydrophobic group 12 and the polymerizable group 13 of the cationic polymerizable surfactant 2 The 2 ′ hydrophobic group 12 ′ and the polymerizable group 13 ′ are adsorbed by hydrophobic interaction, and the cationic group 11 ′ of the cationic polymerizable surfactant 2 ′ is in the direction in which the aqueous dispersion medium is present (water phase). Side), that is, facing away from the mother particle 1.
In this state, for example, by adding a polymerization initiator, the polymerizable groups 13 of the adjacent cationic polymerizable surfactant 2 are polymerized with each other, so that the mother particles 1 are polymer layers 60 as shown in FIG. Toner particles 101 covered with 'are formed.

[Aqueous dispersion medium removal step (dispersion medium removal step)]
Next, toner particles are obtained by removing the aqueous dispersion medium 32 from the dispersion 3 obtained as described above (aqueous dispersion medium removal step).
In the present embodiment, droplets are formed by spraying the dispersion 3, and the aqueous dispersion medium is removed from the droplets to obtain toner particles.

  The spraying of the dispersion liquid 3 may be performed by any method, but is preferably performed by intermittently discharging the droplets of the dispersion liquid 3. As a result, the aqueous dispersion medium can be removed more efficiently while effectively preventing unintentional aggregation of the toner particles, and the productivity of the liquid developer is improved. Further, by removing the aqueous dispersion medium intermittently by discharging droplets of the dispersion liquid, even when a part of the solvent remains in the preparation of the aqueous suspension described above, 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 toner particle manufacturing apparatus as shown in FIGS.
FIG. 6 is a longitudinal sectional view schematically showing a preferred embodiment of a toner particle manufacturing apparatus used for manufacturing the liquid developer of the present invention, and FIG. It is an expanded sectional view. Hereinafter, in FIG. 6, the left side is described as “base end” and the right side is described as “tip”.

  As shown in FIG. 6, the toner particle manufacturing apparatus M1 includes a head M2 that intermittently discharges the dispersion 3 as described above as droplets 9, and a dispersion supply that supplies the dispersion 3 to the head M2. The dispersion medium 32 is removed while the droplet (particulate) dispersion 3 (droplet 9) discharged from the section (aqueous dispersion supply section) M4 and the head section M2 is conveyed to form toner particles 100. It has a dispersion medium removing unit M3 and a collecting unit M5 that collects the manufactured toner particles 100.

  The dispersion supply unit M4 only needs to have a function of supplying the dispersion 3 to the head unit M2, but in the present embodiment, as illustrated, the dispersion supply unit M4 includes a stirring unit M41 that stirs the dispersion 3. is there. Thereby, for example, even if the toner particles 100 are difficult to disperse in the dispersion medium (aqueous dispersion medium) 32, the dispersion liquid 3 in which the toner particles 100 are sufficiently uniformly dispersed is supplied to the head unit M2. be able to.

The head portion M2 has a function of discharging the dispersion liquid 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 dispersion liquid 3 is stored in the dispersion liquid storage part M21.

The dispersion 3 stored in the dispersion storage part M21 is discharged as droplets 9 to the dispersion medium removal part M3 from the discharge part M23 forming the nozzle 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 dispersion liquid 3 and the toner particles 100 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 dispersion liquid 3 (droplet 9) may have bubbles. There is a possibility of embracing.

  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 figure)) is a dispersion liquid. 3 preferably has liquid repellency (water repellency). Thereby, it can prevent effectively that the dispersion liquid 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 dispersion 3. Further, by effectively preventing the dispersion liquid 3 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 between the droplets is small). Variation in the 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. 7, 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 dispersion liquid 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 dispersion liquid 3 is discharged from the discharge part M23.

  When one discharge of the dispersion liquid 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, a pressure (pressure in the positive direction) acting from the dispersion liquid supply unit M4 to the discharge unit M23 acts on the dispersion liquid 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 dispersion liquid 3 corresponding to the discharge amount of the dispersion liquid 3 is supplied from the dispersion liquid supply part M4 to the dispersion liquid storage part M21. The

By applying the voltage as described above at a predetermined cycle, the piezoelectric element M22 vibrates and the granular dispersion liquid 3 is repeatedly discharged.
In this way, by performing the discharge (injection) of the dispersion liquid 3 by the pressure pulse generated by the vibration of the piezoelectric body M222, the dispersion liquid 3 can be intermittently discharged one by one. The shape of the droplet 9 becomes stable. 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. Therefore, the ejected droplets 9 can be effectively prevented from colliding and aggregating, and the formation of irregularly shaped toner particles 100 can be more effectively prevented.
The initial velocity of the dispersion 3 (droplet 9) discharged from the head M2 to the dispersion medium removal unit M3 is, for example, preferably 0.1 to 10 m / sec, and preferably 2 to 8 m / sec. More preferred. When the initial speed of the dispersion liquid 3 is less than the lower limit, the productivity of the toner is lowered. On the other hand, when the initial velocity of the dispersion liquid 3 exceeds the upper limit, the sphericity of the finally obtained toner particles tends to decrease.

  Moreover, the viscosity of the dispersion 3 discharged from the head part M2 is not particularly limited, but is preferably 0.5 to 200 [mPa · s], for example, 1 to 25 [mPa · s]. Is more preferable. When the viscosity of the dispersion liquid 3 is less than the lower limit, it is difficult to sufficiently control the size of the discharged dispersion liquid 3, and the dispersion of toner particles finally obtained may increase. On the other hand, when the viscosity of the dispersion liquid 3 exceeds the upper limit, the diameter of the formed particles increases, the discharge speed of the dispersion liquid 3 decreases, and the amount of energy required for discharging the dispersion liquid 3 tends to increase. Show. In addition, when the viscosity of the dispersion 3 is particularly large, the dispersion 3 cannot be ejected as droplets.

Moreover, the dispersion liquid 3 discharged from the head part M2 may be cooled in advance. By cooling the dispersion 3 in this manner, for example, unintentional evaporation (volatilization) of the dispersion medium 32 from the dispersion 3 near 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 dispersion liquid 3 due to a decrease in the opening area of the discharge portion over time, and a toner with particularly small variation in size and shape between the particles. Obtainable.
Further, the discharge amount of one droplet of the dispersion liquid 3 is slightly different depending on the content of the toner particles 100 in the dispersion liquid 3 and the like, but is preferably 0.05 to 500 pl, and preferably 0.5 to 50 pl. Is more preferable. By setting the discharge amount of one droplet of the dispersion 3 to a value in such a range, the formed toner particles 100 can have an appropriate particle size.

  In the present embodiment, the content and particle size of the toner particles 100 in the dispersion 3 are prevented so that two or more toner particles 100 are not included in the droplet 9 discharged from the discharge portion M23 (nozzle). Etc. are set. As a result, as shown in FIG. 3, the formed droplets 9 include one toner particle 100 in the dispersion medium 32 or are substantially composed of only the dispersion medium 32 without the toner particles 100. It will be.

Then, the dispersion medium 32 is removed from the droplet 9 containing one toner particle 100 in the dispersion medium 32, whereby the toner particle 100 is obtained.
On the other hand, the liquid droplets that are substantially composed of only the dispersion medium 32 without including the toner particles 100 are removed when the dispersion medium 32 is removed. Further, since the particle size of the toner particles 100 is relatively large with respect to the particle size of the droplet 9, even when a sub-droplet having a smaller particle size than the required main droplet is generated in forming the droplet, It is possible to prevent the toner particles 100 from being present in the sub-droplet. Such a sub-droplet does not contain the toner particles 100 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 toner particles 100 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, the discharge of the granular dispersion liquid 3 cannot follow, and the dispersion of the size of one drop of the dispersion liquid 3 increases, and as a result, toner particles are formed. There is a possibility that the variation in the size of 100 becomes large.

The toner particle manufacturing apparatus M1 having the illustrated configuration has a plurality of head portions M2. And granular dispersion liquid 3 (droplet 9) is discharged from these head parts M2 to dispersion medium removal part M3, respectively.
Each head unit M2 may discharge the dispersion liquid 3 (droplet 9) almost simultaneously, but at least two adjacent head units have different discharge timings of the dispersion liquid 3 (droplet 9). It is preferable that these are controlled. This more effectively prevents the droplets 9 from colliding with each other before the toner particles 100 are formed from the droplets 9 ejected from the adjacent head part M2 to cause unintentional aggregation. Can do.

  Further, as shown in FIG. 6, the toner particle 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. Accordingly, the toner particles 100 can be formed while maintaining the interval between the droplets 9 ejected intermittently 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 toner particles 100 to be formed 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 toner particles 100 formed in the dispersion medium removing unit M3 can be transported more efficiently. Thereby, the collection efficiency of the toner particles 100 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 dispersion 3 discharged to the dispersion medium removal unit M3. .
Further, with such a gas flow supply means M10, the removal rate of the dispersion medium 32 from the dispersion 3 discharged from the discharge unit M23 is easily controlled by adjusting the supply amount of the gas flow. It is also possible.

  The temperature of the gas ejected from the gas ejection port M7 varies depending on the composition of the toner particles 100 and the dispersion medium 32 contained in the dispersion 3, but is usually preferably 0 to 70 ° C, and 15 to 60 ° C. It is more preferable that When the temperature of the gas ejected from the gas ejection port M7 is within such a range, the resulting toner particles 100 are contained in the droplet 9 while the uniformity and stability of the shape of the toner particles 100 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 ejected from the gas ejection port M7 is 50% RH or less, the dispersion medium 32 contained in the dispersion 3 can be efficiently removed in the dispersion medium removal unit M3 described later, and toner particles The productivity of 100 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 resin material constituting the toner particles 100. In other words, the toner particle manufacturing process is preferably performed at a temperature below the glass transition point of the resin material constituting the toner particle 100. This makes it difficult for the toner particles 100 to stick to each other when forming the droplets 9 of the dispersion liquid 3, thereby preventing the joining of the toner particles 100.

  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 toner particles 100 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 toner particles 100 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. When the pressure in the housing M31 is a value within the above range, for example, rapid removal of the dispersion medium 32 from the droplet 9 (boiling phenomenon) or the like can be effectively prevented, and the irregularly shaped toner particles 100 can be prevented. The toner particles 100 can be more efficiently produced while sufficiently preventing the occurrence of the toner. 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 toner particles 100 (droplets 9), that is, a positive voltage, to the inner surface of the housing M31 by the voltage applying means M8, the toner particles 100 are effectively adhered to the inner surface of the housing M31. Can be prevented. As a result, the generation of irregularly shaped toner particles 100 can be more effectively prevented, and the collection efficiency of the toner particles 100 can be improved.

Further, the housing M31 has a reduced diameter portion M311 in which the inner diameter becomes smaller in the vicinity of the recovery portion M5 in the downward direction in FIG. By forming such a reduced diameter portion M311, the toner particles 100 can be efficiently collected.
The toner particles 100 formed as described above are collected by the collection unit M5.
In addition, the toner particles 100 obtained as described above may be any particulate material obtained by removing the dispersion medium 32 of the dispersion liquid 3. For example, a part of the dispersion medium remains inside the toner particles 100. May be.

The obtained toner particles 100 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 toner particles can be further improved, and the water content in the toner particles can be reduced. Also, the water content can be reduced in the same manner as described above by subjecting the obtained toner particles 100 to a treatment such as aeration or leaving the toner particles 100 in a reduced-pressure atmosphere.
In addition, the toner particles 100 as described above may be subjected to various processes such as a classification process and an external addition process as necessary.

[Dispersion process]
Next, the toner particles 100 obtained as described above are dispersed in an insulating liquid (dispersing step). Thereby, a liquid developer in which the toner particles 100 are dispersed in the insulating liquid (supported liquid) is obtained.
The toner particles 100 can be dispersed in the insulating liquid by any method, but it is preferable to add the toner particles 100 to the stirred insulating liquid. As a result, while preventing the toner particles 100 from unintentionally agglomerating when adjusting the liquid developer, the obtained liquid developer can stably maintain a good dispersion state of the toner particles for a long period of time. it can.

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 the two. 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. 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, the image formation using the liquid developer of one color has been described. However, when forming an image using a plurality of color toners, an image of each color is formed using a developer of a plurality of colors. 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 columnar halogen lamp, F1b is a roll base, F1c is an elastic body, F2 is a pressure roll, F2a is a rotating shaft, and F2b is a roll base. F2c is an elastic body, F3 is a heat-resistant belt, F4 is a belt stretching 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, L is It is a pressing 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. As a result, the elastic bodies F1c and 2c have different thicknesses, but the elastic bodies F1c and 2c 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 columnar halogen lamps F1a and F1a constituting a heat source are built in the heat fixing roll F1, and the heating elements of these columnar halogen lamps F1a and F1a are arranged at different positions. Yes. Then, by selectively lighting each columnar halogen lamp F1a, F1a, a fixing nip portion where the heat-resistant belt F3 is wound around the heat fixing roll F1 and a portion where the belt stretching member F4 is in sliding contact with the heat fixing roll F1 are formed. Temperature control can be easily performed under different conditions or 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 these.
For example, each part constituting the toner particle manufacturing 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.

  Further, in the above-described embodiment, the toner particles obtained in the aqueous dispersion medium removing step are once collected and then used for the dispersion step. However, the toner particles are directly collected in the dispersion step without being collected as a powder. You may use for. For example, a toner particle manufacturing apparatus as shown in the figure may have a dispersion unit that stores an insulating liquid and is supplied with the manufactured toner particles. As a result, the liquid developer can be produced more efficiently and unintentional aggregation between the toner particles can be more effectively prevented.

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. Therefore, even if the dispersion liquid 3 stored in the dispersion liquid storage part M21 has a relatively high viscosity, it can be reliably discharged from the discharge part M23. Moreover, even if the dispersion liquid 3 stored in the dispersion liquid storage unit M21 has a relatively large cohesive force (surface tension), it can be discharged as fine droplets. The particle diameter of the toner particles 100 can be controlled to a relatively small value.
In this way, by adopting the configuration as shown in the figure, the toner particles can have a desired shape and size even when a material having higher viscosity or a material having a high cohesive force is used as the dispersion liquid 3. Since it 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 as shown in the figure, since the dispersion liquid 3 is discharged by the converged pressure pulse, the size of the dispersion liquid 3 to be discharged is large even when the area (opening area) of the discharge portion M23 is relatively large. The thickness can be made relatively small. That is, even when it is desired to make the particle size of the toner particles relatively small, the area of the discharge portion M23 can be increased. Thereby, even if the dispersion liquid 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 or the like may be disposed between the acoustic lens M25 and the ejection unit M23 toward the ejection 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 dispersion liquid is intermittently ejected from the head portion by the piezoelectric pulse. However, other methods can be used as a dispersion liquid ejection method (injection method). 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. 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, the removal of the dispersion medium may not be performed by discharging the dispersion liquid. For example, the toner particles may be filtered off and dried by filtering the dispersion.
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 aqueous dispersion may be obtained by heating the dispersion in which the dispersoid in the solid state is dispersed to temporarily convert the dispersoid into a liquid state, and cooling the aqueous emulsion to obtain an aqueous suspension.
In the above-described embodiment, the polymer layer is formed on the surface of the mother particle in the aqueous suspension. However, the polymer layer may be formed after the mother particle is once dried and isolated. .

[1] Production of toner (Example 1)
First, as a resin material, a polyester resin having a —SO ₃ ^— group (sulfonic acid Na group) in the side chain (softening temperature: 120.5 ° C., acid value: 28.8): 80 parts by weight, and as a colorant Cyan pigment (manufactured by Dainichi Seika Co., Ltd., Pigment Blue 15: 3): 20 parts by weight was prepared. The polyester resin had 0.1 mol of —SO ₃ ^— group in 100 g of the polyester resin.

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 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 125-135 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 130 ° 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 40 ° 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 is added to 250 parts by weight of toluene, and the mixture is treated for 1 hour using an ultrasonic homogenizer (output: 400 μA), whereby the self-dispersing resin of the kneaded product is obtained. A dissolved solution was obtained. In such a solution, the pigment was uniformly finely dispersed.

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.).
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 3 μm was uniformly dispersed was obtained.
Thereafter, toluene in the aqueous emulsion was removed under 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 25.0 wt%. The volume average particle diameter of the dispersoid (mother particles) dispersed in the suspension was 1.0 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.).

  Next, after adding 1.25 parts by weight of dimethylaminoethylmethyl chloride methacrylate as a cationic polymerizable surfactant to 400 parts by weight of the obtained aqueous suspension and mixing, ultrasonic waves were irradiated for 15 minutes. And processed. Next, 12 parts by weight of isobornyl methacrylate and 8 parts by weight of dodecyl methacrylate were mixed and mixed with stirring. Further, dimethylaminoethyl methyl chloride methacrylate: 1.5 parts by weight was added and mixed, and the mixture was ultrasonicated again. Was irradiated 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 raising the internal temperature of the reaction vessel to 80 ° C., 0.6 part by weight of 2,2′-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator was dissolved in 20 parts by weight of ion-exchanged water 2 2,2′-Azobis (2-methylpropionamidine) dihydrochloride aqueous solution was added dropwise, and polymerization was carried out at 80 ° C. for 6 hours while introducing nitrogen. After completion of the polymerization, the pH was adjusted to around 6 with disodium citrate and ultrafiltration was performed to obtain a dispersion in which toner particles were dispersed in an aqueous dispersion medium.

The volume average particle diameter of the toner particles in the obtained dispersion was measured and found to be 1.15 μm. The volume average particle size of the toner particles was measured using a laser diffraction / scattering particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.).
The dispersion liquid obtained as described above was put into the dispersion liquid supply section of the toner particle manufacturing apparatus having the configuration shown in FIGS. While stirring the aqueous suspension in the dispersion supply unit with the stirring means, the metering pump supplied the head suspension to the head unit and discharged (jetted) 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. Note that the temperature of the dispersion in the dispersion supply unit was adjusted to 25 ° C.

  The dispersion liquid is discharged at a dispersion temperature of 25 ° C. in the head part, 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 discharged from the head part. It was performed in a state where the discharge amount of one drop was adjusted to 4 pl (particle size: 20.8 μm). Further, the dispersion liquid was discharged so that the discharge timing of the dispersion liquid was shifted in at least adjacent head parts among the plurality of head parts.

Further, at the time of discharging the dispersion, air having a temperature of 25 ° C., a humidity of 27% RH, and a flow velocity of 3 m / second was jetted vertically downward from the gas jetting 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 to prevent the dispersion liquid (dried fine particles) from adhering to the inner wall.

In the dispersion medium removing section, the dispersion medium was removed from the discharged dispersion, and a large number of dry fine particles (toner particles) were formed.
The dried fine particles formed in the dispersion medium removing unit were collected with a cyclone. The water content of the collected dry fine particles was 0.42 wt%.
Next, the recovered dry fine particles: 20 parts by weight, polyamine-based dispersant: 2 parts by weight, aluminum stearate as a charge control agent: 0.25 parts by weight, insulating liquid: 80 parts by weight A liquid developer was obtained by dispersing. As the insulating liquid, liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd .; trade name “liquid paraffin”) was used. The electrical resistance of this insulating liquid at room temperature (20 ° C.) was 2.4 × 10 ¹⁵ Ωcm, and the dielectric constant of the insulating liquid was 2.3.

(Example 2)
Except for using a styrene-acrylic acid ester copolymer having a —SO ₃ ^— group (sulfonic acid anion group) in the side chain (softening temperature: 130.5 ° C., acid value: 10.2) as the resin material, A liquid developer was produced in the same manner as in Example 1.
(Example 3)
As the resin material, -COO the side chain ^- group (carboxylate anion group) polyester resin having a (softening temperature: 120.5 ° C., acid value: 8.0) except for using, in the same manner as in Example 1 Thus, a liquid developer was produced.

(Examples 4 to 6)
A liquid developer was produced in the same manner as in Example 1 except that a polyester resin having an acid value shown in Table 1 was used.
(Example 7)
A liquid developer was produced in the same manner as in Example 1 except that the polymer layer was formed as follows.

Aqueous suspension obtained in the same manner as in Example 1: 1.25 parts by weight of dimethylaminoethyl methyl chloride methacrylate as a cationic polymerizable surfactant was added to and mixed with 400 parts by weight, followed by ultrasonication. Was irradiated for 15 minutes. Next, 20 parts by weight of isobornyl methacrylate: 20 parts by weight are mixed and mixed by stirring. Further, dimethylaminoethyl methyl chloride methacrylate: 1.5 parts by weight is added and mixed, and again irradiated with ultrasonic waves for 30 minutes. did. 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 raising the internal temperature of the reaction vessel to 80 ° C., 0.6 part by weight of 2,2′-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator was dissolved in 20 parts by weight of ion-exchanged water 2 2,2′-Azobis (2-methylpropionamidine) dihydrochloride aqueous solution was added dropwise, and polymerization was carried out at 80 ° C. for 6 hours while introducing nitrogen. After completion of the polymerization, the pH was adjusted to around 6 with disodium citrate and ultrafiltration was performed to obtain a dispersion in which toner particles were dispersed in an aqueous dispersion medium.
The volume average particle diameter of the toner particles in the obtained dispersion was measured and found to be 1.03 μm. The volume average particle size of the toner particles was measured using a laser diffraction / scattering particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.).

(Comparative Example 1)
First, a polyester resin as a binder resin (polyester resin having no sulfonic acid anion group: softening temperature: 120.5 ° C.): 80 parts by weight and a cyan pigment as a colorant (manufactured by Dainichi Seika Co., Ltd., pigment) Blue 15: 3): 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 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 105-115 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 130 ° 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 polyester resin of the kneaded product was dissolved by treating with an ultrasonic homogenizer (output: 400 μA) for 1 hour. A solution was obtained. In such a solution, the pigment was uniformly finely dispersed.

On the other hand, an aqueous liquid in which sodium dodecylbenzenesulfonate as a dispersant: 1 part by weight and ion-exchanged water: 700 parts by weight were uniformly mixed was prepared.
The stirring speed of the aqueous liquid was adjusted with a homomixer (manufactured by Tokushu Kika Kogyo Co.).
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 3 μm was uniformly dispersed was obtained.

  Thereafter, the toluene in the aqueous emulsion is removed under the conditions of temperature: 100 ° C. and atmospheric pressure: 80 kPa, and after cooling to room temperature, the concentration of the solid fine particles is adjusted by adding a predetermined amount of water. A dispersed aqueous suspension was obtained. 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 (mother particles) dispersed in the suspension was 1.03 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 dispersion liquid supply unit of the toner particle manufacturing apparatus having the configuration shown in FIGS. While stirring the aqueous suspension in the dispersion supply unit with the stirring means, the metering pump supplied the head suspension to the head unit, and discharged (jetted) 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 dispersion 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 4 pl (particle size: 20.8 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 to prevent 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 dry fine particles formed in the dispersion medium removing unit were collected with a cyclone to obtain dry fine particles.

Next, the collected dried fine particles: 20 parts by weight, polyamine-based dispersant: 2 parts by weight, and aluminum stearate as a charge control agent: 1.0 part by weight in an insulating liquid: 80 parts by weight A liquid developer was obtained by dispersing. As the insulating liquid, liquid paraffin (manufactured by Wako Pure Chemical Industries, Ltd .; trade name “liquid paraffin”): 80 parts by weight was used. The electrical resistance of this insulating liquid at room temperature (20 ° C.) was 2.4 × 10 ¹⁵ Ωcm, and the dielectric constant of the insulating liquid was 2.3.

(Comparative Example 2)
A liquid developer was produced in the same manner as in Comparative Example 1 except that a styrene-acrylic acid ester copolymer having no anionic group (softening temperature: 130.5 ° C.) was used as the resin material.
(Comparative Example 3)
A liquid developer was produced in the same manner as in Comparative Example 1 except that a quaternary ammonium group-containing styrene-acrylic acid copolymer (softening temperature 127.4 ° C.) was used as the positively chargeable resin material.
Table 1 shows the manufacturing conditions and the like of the liquid developer for each of the above Examples and Comparative Examples.

[2] Evaluation Each liquid developer 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 polymer layer deposition was immersed in the liquid developer obtained in each of Examples and Comparative Examples, and the distance between the electrodes was 2.0 mm, the applied voltage was 200 V, and the voltage was applied. Toner adhesion amounts m1 [g / m ² ] and m2 [g / m ² ] per unit area on both electrode surfaces were measured by electrophoresis under conditions of 10 seconds. The uniformity was evaluated as (m1 / (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.
Using an image forming apparatus as shown in FIG. 8, the liquid developer to be evaluated was put in a developing machine, and the entire surface was printed in white (solid white). Stop the printer during printing, take out the photoconductor, and put the mending tape on the area 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%.

[2.4] Durability Using an image forming apparatus as shown in FIG. 8, a continuous printing test of 1000 sheets is performed, and the image density Xs at the start time and the image density Xe of the 1000th sheet are manufactured by X-Rite Inc. It measured by "X-Rite model 404", and evaluated the value of Xe / Xs according to the following four steps of criteria. ◎ 0.95 or more (almost no change in image density and excellent durability) ○ 0.85 or more to less than 0.95 (image density slightly changes, but is acceptable) △ 0.75 or more Less than 0.85 (the image density is changed and the durability is inferior) x smaller than 0.75 (the image density is significantly lowered and the durability is very inferior)
These results are shown in Table 2.

As apparent from Table 2, all of the liquid developers of the present invention (Examples 1 to 7) were excellent in charging uniformity, fogging, fixing strength, and durability. On the other hand, all of the liquid developers of the comparative examples were inferior in charging uniformity, fogging, fixing strength, and durability.
In addition, the liquid developer was manufactured and evaluated in the same manner as described above except that Pigment Red 122, Pigment Yellow 180, and Carbon Black (Printex L, manufactured by Degussa) were used as the colorant instead of the cyan pigment. As a result, the same result as above was obtained.

  Further, the structure near the head portion of the toner particle manufacturing apparatus is changed from the configuration shown in FIG. 7 to the configuration shown in FIGS. As a result of production and evaluation, results similar to the above were obtained. In addition, in the toner particle manufacturing apparatus provided with the head portion as shown in FIGS. 11 to 14, even when the diameter of the discharge portion is reduced and the concentration of the dispersion liquid is relatively high, the toner particles are preferably discharged. The results were obtained in the same manner as above. In addition, since a high-concentration dispersion was used, the time required for drying could be shortened, and productivity was improved.

FIG. 4 is a diagram illustrating an example of toner particles constituting the liquid developer of the present invention. It is a longitudinal cross-sectional view which shows typically an example of a structure of the kneader used for the manufacturing method of the liquid developer of this invention, and a cooler. It is a figure which shows an example of the process of forming a polymer layer in the mother particle surface. It is a figure which shows another example of the process of forming a polymer layer on the mother particle surface. FIG. 6 is a diagram illustrating another example of toner particles constituting the liquid developer of the present invention. FIG. 2 is a longitudinal sectional view schematically showing a preferred embodiment of a 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 toner particle manufacturing apparatus shown in FIG. 6. 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 toner particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a toner particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a toner particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a toner 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 section K7 ... Kneaded material 1 ... Base particles 11, 11 '... Cationic groups 12, 12 '... hydrophobic group 13, 13' ... polymerizable group 14, 14 '... anionic group 2,2' ... cationic polymerizable surfactant 50 ... hydrophobic region 60, 60 '... polymer layer 100, 101 ... toner particles M1 ... Toner particle manufacturing apparatus M2 ... Head part M21 ... Dispersion storage part M22 ... Piezoelectric element M221 ... Part electrode M222 ... Piezoelectric body M223 ... Upper electrode M23 ... Discharge part M24 ... Diaphragm M25 ... Acoustic lens M26 ... Pressure pulse converging part M3 ... Dispersion medium removal part M31 ... Housing M311 ... Reduced diameter part M4 ... Dispersion supply part (aqueous system) Dispersion supply unit) M41 ... Stirring means M5 ... Recovery part M7 ... Gas injection port M8 ... Voltage application means M10 ... Gas flow supply means M101 ... Duct M11 ... Heat exchanger M12 ... Pressure adjusting means M121 ... Connecting pipe M122 ... Diameter expansion Part M123 ... Filter M13 ... Diaphragm member P ... Pump 3 ... Dispersion liquid 32 ... Dispersion medium (aqueous dispersion medium) 9 ... Droplet P1 ... Image forming apparatus P2 ... Photoconductor P3 ... Charger P4 ... Exposure P10 ... Developer P11 ... Developer container P12 ... coating roller P13 ... developing roller P14 ... liquid developer coating layer P15 ... metery Blade P16 ... roller core P17 ... developing roller cleaning blade P18 ... intermediate transfer roller P19 ... secondary transfer roller P20 ... information recording medium P21 ... neutralizing light P22 ... cleaning blade P23 ... cleaning blade P24 ... charging blade F40 ... fixing device F1 ... heat fixing roll (heating roll) F1a ... column halogen lamp F1b ... roll base material F1c ... elastic body F2 ... pressure roll F2a ... rotating shaft F2b ... roll base material F2c ... elastic body F3 ... heat-resistant belt F4 ... belt stretching member F4a ... Projection wall F4f ... Recess F5 ... Sheet material F5a ... Unfixed toner image F6 ... Cleaning member F9 ... Spring

Claims (10)

A positively chargeable liquid developer in which toner particles are dispersed in an insulating liquid,
The toner particles are coated with a polymer layer having a repeating structural unit derived from a cationic polymerizable surfactant having a cationic group, a hydrophobic group, and a polymerizable group on a mother particle having an anionic group on the surface. A liquid developer, characterized in that   The liquid developer according to claim 1, wherein the resin material constituting the mother particle includes at least one of a polyester resin and a styrene-acrylic acid ester copolymer.   3. The liquid developer according to claim 1, wherein an acid value of a resin material constituting the mother particle is 8 to 50 KOH mg / g. The base particles on its surface, as the anionic group, -COO ^- group, -SO ₃ ^- of the groups, the liquid developer according to any one of claims 1 to 3 and has at least one. A method for producing a liquid developer according to any one of claims 1 to 4,
Obtaining the mother particles having the anionic group on the surface;
A polymer layer forming step of coating the mother particle with a polymer layer by polymerizing the cationic polymerizable surfactant in the vicinity of the surface of the mother particle having the anionic group on the surface. A method for producing a liquid developer.   The method for producing a liquid developer according to claim 5, wherein the polymer layer forming step is performed in an aqueous dispersion in which the base particles having the anionic group on the surface are dispersed.   The method for producing a liquid developer according to claim 6, wherein in the polymer layer forming step, the cationic polymerizable surfactant is added to the aqueous dispersion and mixed, and then a polymerization initiator is added to perform emulsion polymerization.   In the polymer layer forming step, the cationic polymerizable surfactant is added to and mixed with the aqueous dispersion, followed by emulsification by adding a hydrophobic monomer and a cationic polymerizable surfactant, followed by emulsification by adding a polymerization initiator. The method for producing a liquid developer according to claim 6 or 7, which is obtained by polymerization. In the polymer layer forming step, the step of adding the cationic polymerizable surfactant to the aqueous dispersion and mixing and irradiating with ultrasonic waves; and
Adding a hydrophobic monomer and mixing;
Adding and mixing the cationic polymerizable surfactant and irradiating with ultrasonic waves;
The method for producing a liquid developer according to claim 6, wherein the step of emulsion polymerization by adding a polymerization initiator is sequentially performed. In the polymer layer forming step, the step of adding the cationic polymerizable surfactant to the aqueous dispersion and mixing and irradiating with ultrasonic waves; and
Adding and mixing a hydrophobic monomer and a crosslinkable monomer and / or a monomer represented by the following general formula (1);
A step of adding a cationic polymerizable surfactant having a cationic group, a hydrophobic group and a polymerizable group, mixing and irradiating with ultrasonic waves, and
The method for producing a liquid developer according to claim 6, wherein the step of emulsion polymerization by adding a polymerization initiator is sequentially performed.

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