JP4760092B2 - Liquid developer, image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to a liquid developer, an image forming method, and an image forming apparatus.

A dry toner method in which a toner composed of a material containing a colorant such as a pigment and a binder resin is used in a dry state as a developer used to develop the electrostatic latent image formed on the latent image carrier. And a method using a liquid developer (for example, see Patent Document 1) in which toner is dispersed in an electrically insulating carrier liquid (insulating liquid).
The method using dry toner handles solid-state toner, so there are advantages in handling, but there are concerns about adverse effects on the human body due to powder, as well as contamination due to scattering of toner, and when toner is dispersed There is a problem with uniformity. Further, the dry toner has a problem that the particles are likely to aggregate and it is difficult to sufficiently reduce the size of the toner particles, and it is difficult to form a toner image with high resolution. In addition, when the size of the toner particles is relatively small, the problem due to the powder as described above becomes more remarkable.

  On the other hand, in the method using the liquid developer, the toner particles are effectively prevented from aggregating in the liquid developer, so that it is possible to use fine toner particles, and the binder resin has a low softening point. (Low softening temperature) can be used. As a result, in the method using a liquid developer, fine line image reproducibility is good, gradation reproducibility is good, color reproducibility is excellent, and it is also excellent as a high-speed image forming method. It has characteristics.

However, since the insulating liquid that has been used in conventional liquid developers is mainly composed of petroleum-based hydrocarbons, it adversely affects the environment when, for example, it goes out of an image forming apparatus or the like. There was concern.
In general, in a liquid developer, an insulating liquid adheres to the surface of toner particles during fixing. In the conventional liquid developer, there is also a problem that the insulating liquid adhering to the surface of the toner particles decreases the fixing strength.

JP 7-152256 A

  An object of the present invention is to provide a liquid developer which is excellent in fixing characteristics and long-term stability and is environmentally friendly. Another object of the present invention is to provide an image forming method and an image forming apparatus using such a liquid developer.

Such an object is achieved by the present invention described below.
The liquid developer of the present invention comprises an insulating liquid mainly having an unsaturated fatty acid glyceride, toner particles dispersed in the insulating liquid, an antioxidant for preventing oxidation of the unsaturated fatty acid glyceride, and a polyether. And an oxidative polymerization accelerator that promotes an oxidative polymerization reaction of the unsaturated fatty acid glyceride encapsulated by coating.
In the liquid developer of the present invention, the oxidative polymerization accelerator is preferably a fatty acid metal salt.
In the liquid developer of the present invention, the content of the oxidative polymerization accelerator in the liquid developer is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the unsaturated fatty acid glyceride.
In the liquid developer according to the aspect of the invention, it is preferable that the encapsulation is performed by adsorbing the oxidative polymerization accelerator to the porous body and then covering the porous body.
In the liquid developer of the present invention, the content of the antioxidant in the insulating liquid is preferably 0.01 to 10 wt%.
In the liquid developer of the present invention, the antioxidant is preferably vitamin C.
In the liquid developer of the present invention, the fatty acid metal salt is preferably zinc octylate .
In the image forming method of the present invention , a latent image is formed on the photoreceptor by exposure,
Insulating liquid mainly containing unsaturated fatty acid glyceride, toner particles dispersed in the insulating liquid, antioxidant for preventing oxidation of unsaturated fatty acid glyceride , and glyceride encapsulated by coating with polyether Developing the latent image using a liquid developer containing an oxidative polymerization accelerator that promotes the oxidative polymerization reaction of
Transfer the developed image to a recording medium,
The image transferred to the recording medium is heated and pressurized to be fixed on the recording medium .
With the above configuration, it is possible to provide an environmentally friendly liquid developer that is excellent in fixing characteristics and long-term stability.
The liquid developer of the present invention is a liquid developer in which toner particles are dispersed in an insulating liquid,
The insulating liquid is mainly composed of unsaturated fatty acid glycerides and contains an antioxidant,
The liquid developer contains an oxidative polymerization accelerator that accelerates the oxidative polymerization reaction of the glycerides,
The oxidation polymerization accelerator is contained in an encapsulated state.
Thereby, it is possible to provide a liquid developer that is excellent in fixing characteristics and long-term stability and is environmentally friendly.

In the liquid developer of the present invention, the oxidative polymerization accelerator is preferably a fatty acid metal salt.
Thereby, the oxidative polymerization of unsaturated fatty acid glycerides can be effectively advanced during fixing while more reliably maintaining the stability of the liquid developer during storage.

In the liquid developer of the present invention, the content of the oxidative polymerization accelerator in the liquid developer is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the glyceride.
Thereby, the oxidative polymerization reaction of unsaturated fatty acid glycerides can be more reliably advanced at the time of fixing while sufficiently preventing the oxidative polymerization reaction during storage of the liquid developer.
In the liquid developer of the present invention, the encapsulation is preferably performed by adsorbing the oxidative polymerization accelerator to the porous body and then coating the porous body with a polyether.
Thereby, the oxidative polymerization reaction of unsaturated fatty acid glycerides can be more reliably advanced at the time of fixing while sufficiently preventing the oxidative polymerization reaction during storage of the liquid developer. In addition, the dispersibility of unsaturated fatty acids in glycerides is higher.

In the liquid developer of the present invention, the content of the antioxidant in the insulating liquid is preferably 0.01 to 10 wt%.
As a result, during the storage of the liquid developer, the oxidative polymerization reaction of fats and oils composed of unsaturated fatty acids can be more reliably prevented.
In the liquid developer of the present invention, the thermal decomposition temperature of the antioxidant is preferably not more than the fixing temperature at the time of fixing.
Thereby, at the time of storage, the oxidative polymerization reaction can be effectively promoted at the time of heating such as fixing while preventing the unintended oxidative polymerization reaction from occurring.

In the liquid developer of the present invention, the thermal decomposition temperature of the antioxidant is preferably 200 ° C. or lower.
As a result, the function of the antioxidant can be sufficiently exerted during storage of the liquid developer, and the function of the antioxidant is lowered during fixing, and the oxidative polymerization reaction of unsaturated fatty acid glycerides. Can be promoted.

In the liquid developer of the present invention, the antioxidant is preferably vitamin C.
Vitamin C is an environmentally friendly component, and since it is a component that has a small influence on the liquid developer caused by oxidation of itself, the liquid developer can be made more environmentally friendly. Vitamin C has a relatively low thermal decomposition temperature, so that it can sufficiently function as an antioxidant during storage of a liquid developer, and as an antioxidant during fixing. The function can be reduced and the oxidative polymerization reaction of unsaturated fatty acid glycerides can be promoted.

Hereinafter, preferred embodiments of the liquid developer of the present invention will be described in detail.
The liquid developer of the present invention includes at least an insulating liquid, an oxidation polymerization accelerator, and toner particles.
<Insulating liquid>
First, the insulating liquid used for the liquid developer of the present invention will be described.

The insulating liquid used in the present invention is mainly composed of unsaturated fatty acid glycerides and contains an antioxidant. The unsaturated fatty acid glyceride refers to an ester of an unsaturated fatty acid and glycerin.
By the way, the conventional liquid developer has mainly used petroleum-based hydrocarbons as the insulating liquid. Insulating liquids that have been used in the past have been feared to adversely affect the environment when, for example, the insulating liquid is used outside the image forming apparatus.

In contrast, unsaturated fatty acid glycerides (hereinafter also simply referred to as unsaturated fatty acid glycerides) are environmentally friendly components. Accordingly, it is possible to reduce the influence on the environment due to volatilization of the insulating liquid during use such as fixing and disposal of the liquid developer. As a result, an environmentally friendly liquid developer can be provided.
Examples of the unsaturated fatty acid constituting the unsaturated fatty acid glyceride include monounsaturated fatty acids represented by oleic acid and palmitoleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid, docosahexaenoic acid ( DHA), polyunsaturated fatty acids represented by eicosapentaenoic acid (EPA) answer, and one or more of these can be used.

Such unsaturated fatty acid glycerides can be obtained efficiently from natural oils such as oils derived from plants such as soybean oil, rapeseed oil, linseed oil and cottonseed oil, and oils derived from animals such as herring oil and sardine oil. Can do.
The “insulating liquid mainly composed of unsaturated fatty acid glycerides” means that the content of unsaturated fatty acid glycerides in the insulating liquid is 50 wt% or more, preferably 90 wt% or more. More preferably 95 wt% or more, and even more preferably 97 wt% or more.

In the liquid developer of the present invention, the insulating liquid contains an antioxidant in addition to the unsaturated fatty acid glyceride and the oxidative polymerization accelerator described above.
By the way, the unsaturated fatty acid glyceride as described above is a component that is generally easily oxidized. Therefore, in a liquid developer using an insulating liquid composed of unsaturated fatty acid glycerides, the insulating liquid is likely to deteriorate due to oxidation of unsaturated fatty acid glycerides, and the dispersibility of toner particles and the storage stability of the toner itself are reduced. The problem was easy to occur.

  However, the use of an antioxidant as in the present invention prevents deterioration of unsaturated fatty acid glycerides due to oxidation even when the liquid developer is stored for a long period of time or when the liquid developer is subjected to a relatively high temperature. be able to. That is, the storage stability (long-term stability) of the liquid developer is high. In addition, the dispersion state of the toner particles can be improved over a long period of time. That is, the storage stability of the liquid developer can be increased.

  Examples of the antioxidant as described above include vitamin E such as tocopherol, d-tocopherol, dl-α-tocopherol, acetic acid-α-tocopherol, dl-α-tocopherol acetate, tocopherol acetate, α-tocopherol and the like, ascorbic acid , Vitamin C such as ascorbate, ascorbic acid stearate, dibutylhydroxytoluene, butylhydroxyanisole, green tea extract, fresh coffee extract, sesamol, sesaminol, etc., one or more of these Can be used in combination.

  Among the above, when vitamin E is used, the following effects are obtained. In other words, vitamin E is an environmentally friendly component, and is a component that has a small influence on the liquid developer due to oxidation of the substance itself, so that the liquid developer can be made more environmentally friendly. . Vitamin E can be suitably used as an antioxidant because of its high dispersibility in unsaturated fatty acid glycerides as described above. In addition, the combined use of vitamin E and the unsaturated fatty acid glyceride as described above can further improve the affinity between the insulating liquid and the toner material, and as a result, the storage stability of the liquid developer is further improved. To do.

  Moreover, among the above-mentioned, when vitamin C is used, the following effects are acquired. That is, like the above-mentioned vitamin E, vitamin C is an environmentally friendly component, and since it is a component having a small influence on the liquid developer caused by oxidation of itself, the liquid developer is more environmentally friendly. It can be friendly to you. Vitamin C has a relatively low thermal decomposition temperature, so that it can fully function as an antioxidant when storing a liquid developer or idling an image forming apparatus, and at the time of fixing. In, the function as an antioxidant can be reduced, and the oxidative polymerization reaction of unsaturated fatty acid glycerides can be promoted by an oxidative polymerization accelerator described later.

Moreover, it is preferable to use a fat-soluble antioxidant as the antioxidant. Thereby, the dispersibility to unsaturated fatty acid glyceride improves.
Further, as the antioxidant, those having a thermal decomposition temperature equal to or lower than the fixing temperature at the time of fixing can be used. This more reliably prevents the unsaturated fatty acid glyceride from being oxidized during storage of the liquid developer or idling of the image forming apparatus, and in the insulating liquid adhering to the surface of the toner particles during fixing. The antioxidant can be thermally decomposed. Thereby, the effect of antioxidant falls and the oxidative polymerization reaction of unsaturated fatty acid glyceride can be efficiently promoted by the oxidative polymerization accelerator described later.

  Specifically, the thermal decomposition temperature of the antioxidant is preferably 200 ° C. or lower, and more preferably 180 ° C. or lower. As a result, the function of the antioxidant can be sufficiently exerted during storage of the liquid developer, and the function of the antioxidant is lowered during fixing, and the antioxidant is unsaturated by an oxidation polymerization accelerator described later. The oxidative polymerization reaction of fatty acid glycerides can be promoted.

The content of the antioxidant in the insulating liquid is preferably 0.01 to 10 wt%, more preferably 0.1 to 5 wt%, and more preferably 1 to 5 wt%. This can more reliably prevent the oxidation of unsaturated fatty acid glycerides during storage of the liquid developer and idling of the image forming apparatus.
The electrical resistance of the insulating liquid as described above at room temperature (20 ° C.) is preferably 1 × 10 ⁹ Ωcm or more, more preferably 1 × 10 ¹¹ Ωcm or more, and 1 × 10 ¹³ Ωcm or more. More preferably.

The dielectric constant of the insulating liquid is preferably 3.5 or less.
The iodine value of the insulating liquid is not particularly limited, but is preferably 90 or more, more preferably 120 to 180. As a result, the oxidation polymerization reaction can proceed efficiently, and the fixing strength when the toner particles are fixed on the recording medium can be further improved. Further, the affinity with the toner material can be made higher, and as a result, the storage stability of the liquid developer can be made higher.
The insulating liquid may contain components other than unsaturated fatty acid glycerides and antioxidants.

<Oxidation polymerization accelerator>
Next, the oxidation polymerization accelerator will be described.
An oxidative polymerization accelerator that accelerates the oxidative polymerization reaction of unsaturated fatty acid glycerides is dispersed in the insulating liquid.
By the way, normally, in a liquid developer, an insulating liquid adheres to the surface of toner particles at the time of fixing. In the conventional liquid developer, there is a problem that the insulating liquid adhering to the surface of the toner particles reduces the fixing strength.

However, as in the present invention, the insulating liquid that has been the cause of the decrease in the fixing strength is used to improve the fixing strength by curing the fat and oil composed of the unsaturated fatty acid used as the insulating liquid. Can do.
In particular, in the present invention, an oxidative polymerization accelerator is included in an encapsulated state. As a result, it is possible to prevent the oxidative polymerization reaction from proceeding during storage of the liquid developer or idling of the image forming apparatus, and at the time of fixing, the capsule is crushed by the pressure at the time of fixing, thereby promoting oxidative polymerization. The agent and unsaturated fatty acid glyceride come into contact with each other, and the unsaturated fatty acid glyceride is cured. As a result, the fixing strength is improved. In addition, since the unsaturated fatty acid glyceride is cured, it is possible to write the fixed toner image with an aqueous ballpoint pen.

Such an oxidative polymerization accelerator is preferably one that accelerates the oxidative polymerization reaction of unsaturated fatty acid glycerides by supplying oxygen on the recording medium during fixing. Thereby, it is possible to effectively promote the oxidative polymerization reaction at the time of heating such as fixing while preventing the unintended oxidative polymerization reaction from occurring during storage.
Such an oxidative polymerization accelerator is not particularly limited as long as it promotes the oxidative polymerization reaction of unsaturated fatty acid glycerides, and includes various fatty acid metal salts. Among these, one or more of these are combined. Can be used. This makes it possible to effectively advance the oxidative polymerization of unsaturated fatty acid glycerides during fixing while more reliably maintaining the stability of the liquid developer during storage of the liquid developer and idling of the image forming apparatus. Can do.

  Examples of such fatty acid metal salts include resin acid metal salts (for example, cobalt salts, manganese salts, lead salts, etc.), linolenic acid metal salts (for example, cobalt salts, manganese salts, lead salts, etc.), and metal octylates. Salt (for example, cobalt salt, manganese salt, lead salt, zinc salt, calcium salt, etc.), naphthenic acid metal salt (for example, zinc salt, calcium salt, etc.), etc. They can be used in combination.

  The content of the oxidative polymerization accelerator in the liquid developer is preferably 0.01 to 10 parts by weight, and 0.05 to 5 parts by weight with respect to 100 parts by weight of the unsaturated fatty acid glyceride described above. Is more preferable, and 0.1 to 3 parts by weight is more preferable. Thereby, the oxidative polymerization reaction of the unsaturated fatty acid glyceride can proceed more reliably during fixing while sufficiently preventing the oxidative polymerization reaction during storage of the liquid developer.

<Constituent material of toner particles>
Next, materials constituting the toner particles will be described.
The toner particles (toner) constituting the liquid developer of the present invention include at least a binder resin (resin material) and a colorant.
1. Resin Material The toner constituting the liquid developer is composed of a material containing a resin material as a main component.

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

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

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

Examples of the charge control agent include benzoic acid metal salt, salicylic acid metal salt, alkyl salicylic acid metal salt, catechol metal salt, metal-containing bisazo dye, nigrosine dye, tetraphenylborate derivative, quaternary ammonium salt, alkyl Examples include pyridinium salts, chlorinated polyesters, and nitrofunic 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, for example, zinc stearate, zinc oxide, cerium oxide, silica, titanium oxide, iron oxide, fatty acid, fatty acid metal salt, etc. are used as the constituent material (component) of the kneaded product. May be.
The average particle diameter of the toner particles composed of the above materials is preferably 0.1 to 5 μm, more preferably 0.1 to 4 μm, and further preferably 0.5 to 3 μm. preferable. When the average particle diameter of the toner particles is a value within the above range, the variation in characteristics among the toner particles is particularly small, and the reliability of the entire liquid developer is particularly high, while the liquid developer ( The resolution of the image formed by the toner can be made sufficiently high.

The standard deviation of the particle size between toner particles constituting the liquid developer is preferably 1.0 μm or less, more preferably 0.1 to 1.0 μm, and more preferably 0.1 to 0. More preferably, it is 8 μm. As a result, the variation in characteristics among the toner particles is particularly reduced, and the reliability of the entire liquid developer is further improved.
Further, the average value (average circularity) of the circularity R represented by the following formula (I) for the toner particles constituting the liquid developer is preferably 0.85 or more, and 0.90 to 0.00. 99 is more preferable, and 0.92 to 0.99 is even more preferable.

R = L ₀ / L ₁ (I)
(Where, L ₁ [μm] is the circumference of the projected image of the toner particles to be measured, and L ₀ [μm] is the circumference of a perfect circle having an area equal to the area of the projected image of the toner particles to be measured) Represents length)
Thereby, the transfer efficiency and mechanical strength of the toner particles can be made particularly excellent while the particle diameter of the toner particles is sufficiently small.
The standard deviation of the average circularity between the toner particles constituting the liquid developer is preferably 0.15 or less, more preferably 0.001 to 0.10, and 0.001 to 0. More preferably, .05. As a result, variations in characteristics such as charging characteristics and fixing characteristics among the toner particles are particularly reduced, and the reliability of the entire liquid developer is further improved.

Next, an example of a method for producing a liquid developer according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view schematically showing an example of the structure of a kneader and a cooler for producing a kneaded product used for the preparation of an aqueous emulsion, and FIG. 2 is used for producing the liquid developer of the present invention. FIG. 3 is an enlarged cross-sectional view of the vicinity of the head portion of the dry particle manufacturing apparatus shown in FIG. 2. Hereinafter, in FIG. 1, the left side is assumed to be “base end” and the right side is assumed to be “tip”.

The liquid developer of the present invention may be manufactured using any method, but the method of manufacturing the liquid developer according to the present embodiment is composed of a toner material as described above in a dispersion medium. A dispersion preparation step for obtaining a dispersion in which the dispersoid is dispersed, a dispersion medium removal step for removing the dispersion medium to obtain dry fine particles, and a dispersion step for dispersing the dry fine particles in the insulating liquid.
In this embodiment, a case where an aqueous dispersion in which a dispersoid is dispersed in an aqueous dispersion medium composed of an aqueous liquid is used as the dispersion. By using an aqueous dispersion, a liquid developer can be provided in an environmentally friendly manner.

The aqueous dispersion may be prepared by any method, but in the present embodiment, the aqueous dispersion is prepared using a kneaded material containing a colorant and a resin material.
As a constituent material (component) of the kneaded material, in addition to the material constituting the toner as described above, for example, a material used as a solvent such as an inorganic solvent or an organic solvent may be used. Thereby, for example, the efficiency of kneading can be improved, and a kneaded product in which the components are more uniformly mixed can be easily obtained.

<Kneaded material>
Next, an example of a method for obtaining the kneaded material K7 by kneading the raw material K5 containing the toner material as described above 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 includes the toner material as described above. In particular, since the raw material K5 contains a colorant, air contained in the raw material K5 in this step (especially, air entrapped by the colorant) can be efficiently removed, and bubbles are mixed inside the toner particles ( Remaining) can be effectively prevented. The raw material K5 used for kneading is preferably a mixture of these components.

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

In the process part K2, when the screw K22 and the screw K23 rotate, a shearing force is applied to the raw material K5 supplied from the feeder K4, and a uniform kneaded material K7 is obtained.
The total length of the process part K2 is preferably 50 to 300 cm, and more preferably 100 to 250 cm. If the total length of the process part K2 is less than the lower limit, it may be difficult to mix the components in the raw material K5 sufficiently uniformly. On the other hand, when the total length of the process part K2 exceeds the upper limit, depending on the temperature in the process part K2, the number of rotations of the screw K22, the screw K23, and the like, the material K5 is easily denatured by heat, and finally obtained. It may be difficult to sufficiently control the physical properties of the liquid developer (toner).

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

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

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

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

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

  The temperature of the kneaded material K7 in the internal space K31 (at least in the vicinity of the extrusion port K32) is not particularly limited, but is preferably a temperature equal to or higher than the softening temperature of the resin material contained in the raw material K5. As a result, the toner particles can be obtained as a mixture of the constituent components more uniformly, and variations in characteristics (charging characteristics, fixing properties, etc.) among the toner particles can be particularly reduced.

The specific temperature of the kneaded material K7 in the internal space K31 (at least the temperature near the extrusion port K32) is not particularly limited, but is preferably 80 to 150 ° C, more preferably 90 to 140 ° C. preferable. When the temperature of the kneaded material K7 in the internal space K31 is a value within the above range, the kneaded material K7 does not solidify in the internal space K31 and is easily extruded from the extrusion port K32.
In the illustrated configuration, the internal space K31 has a cross-sectional area gradually decreasing portion K33 in which the cross-sectional area gradually decreases in the direction of the extrusion port K32. By having such a cross-sectional area gradually decreasing portion K33, the extrusion amount of the kneaded material K7 extruded from the extrusion port K32 is stabilized, and the cooling rate of the kneaded material K7 in the cooling step described later is stabilized. As a result, the toner produced using the toner has a small variation in characteristics among the toner particles, and has excellent overall characteristics.

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

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

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

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

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

[Crushing process]
Next, the kneaded material K7 that has undergone the cooling process as described above is pulverized. Thus, by pulverizing the kneaded material K7, an aqueous emulsion to be described later can be obtained relatively easily as a dispersion of finer dispersoids. 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 such as a ball mill, a vibration mill, a jet mill, and a pin mill, and a crusher.
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 medium removing 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 the present embodiment, an aqueous emulsion is prepared using the kneaded material as described above.
By using the kneaded product K7 for the preparation of the 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, in the constituent materials of the toner, components (hereinafter also referred to as “hardly dispersible components”) having poor dispersibility with respect to the dispersion medium (aqueous dispersion medium) of the aqueous emulsion described later and aqueous emulsions are used. Even when a component having poor solubility in a solvent contained in a dispersion medium (hereinafter also referred to as “slightly soluble component”) is included, the dispersibility of the dispersoid in the aqueous emulsion is particularly excellent. In addition, in the aqueous suspension 3 (droplet 9) prepared using this aqueous emulsion, the dispersibility of the dispersoid 31 is 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.

  On the other hand, when the raw material which has not been kneaded is used for the preparation of the aqueous emulsion, the hardly dispersible component or the hardly soluble component aggregates and settles in the aqueous emulsion or the aqueous suspension described later. In the aqueous emulsion (and aqueous suspension described later), a dispersoid having a relatively large particle size, which is mainly composed of a hardly dispersible component or a hardly soluble component and is not sufficiently mixed with other components. (A dispersoid having a large particle size mainly composed of a hardly dispersible component and / or a hardly soluble component and a dispersoid mainly composed of a component other than the hardly dispersible component and the hardly soluble component are mixed) The dry fine particles (toner particles) obtained in the aqueous dispersion medium removing step described in detail later have large variations in composition, size, shape, etc. among the particles. As a result, the characteristics of the entire toner (the entire liquid developer) are degraded.

Further, when the pulverized product of the kneaded product obtained as described above is directly used as toner particles without being used in the preparation of an aqueous emulsion as described later, the uniformity of components in the toner (dispersibility) There was a limit to raising it. Further, in such a method, it is particularly difficult to disperse (finely disperse) a pigment that is generally a relatively strong aggregate (which tends to be a strong aggregate).
On the other hand, by using the kneaded material as described above for the preparation of the aqueous emulsion, the toner particles finally obtained are those in which the respective components are sufficiently uniformly compatible and dispersed (finely dispersed).

  Further, in the aqueous emulsion as used in the present embodiment, the dispersoid is liquid (has fluidity and can be deformed relatively easily), so that the dispersoid has a circularity ( The tendency to become a shape with a large (sphericity). Therefore, a suspension (aqueous suspension) prepared using the aqueous emulsion also has a dispersoid having a relatively large circularity (sphericity), and is finally obtained as a result. The toner particles also have a relatively large circularity (sphericity). In addition, in the case of an emulsion in which the dispersoid is liquid (has fluidity and can be deformed relatively easily), the uniformity of the size of the dispersoid can be relatively easily achieved by, for example, stirring the emulsion. It can be high enough. On the other hand, when a suspension prepared for the production of dry fine particles described later is used without passing through an aqueous emulsion, the dispersoid contained in the suspension has a circularity. In particular, the variation in shape and particle diameter between particles is large. Further, in order to suppress such variation in shape, it is conceivable to perform a thermal spheronization treatment at the time of forming the dry fine particles as described later or after the formation of the dry fine particles. If the conditions of the thermal spheronization treatment are not relatively severe, it is difficult to sufficiently reduce the variation in the shape of the resulting dried fine particles. It is easy to cause deterioration of the constituent materials and breakage of the compatibilized state and finely dispersed state of each constituent component in the dry fine particles, and it is difficult to exert sufficient characteristics in the finally obtained liquid developer.

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

[Preparation of kneaded product solution (solution of kneaded product)]
In this embodiment, first, a kneaded product solution in which at least a part of the kneaded product is dissolved is obtained.
The solution can be prepared by mixing the kneaded product and a solvent capable of dissolving at least a part of the kneaded product.
The solvent used for the preparation of the solution may be any solvent as long as it can dissolve at least a part of the kneaded product. 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 specification, 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.

  Moreover, for the purpose of improving the dispersibility of the dispersoid, for example, a dispersant or the like may be used for preparing the aqueous emulsion. Examples of the dispersant include inorganic minerals such as viscosity minerals, silica and tricalcium phosphate, nonionic organic dispersants such as polyvinyl alcohol, carboxymethyl cellulose, and polyethylene glycol, and metal tristearate (for example, aluminum salt). ), Metal distearate (eg, aluminum salt, barium salt, etc.), metal stearate (eg, calcium salt, lead salt, zinc salt, etc.), metal salt of linolenic acid (eg, cobalt salt, manganese salt, lead salt) , Zinc salts, etc.), octanoic acid metal salts (eg, aluminum salts, calcium salts, cobalt salts, etc.), oleic acid metal salts (eg, calcium salts, cobalt salts, etc.), palmitic acid metal salts (eg, zinc salts, etc.) , Metal salts of dodecylbenzenesulfonic acid (for example, sodium salt), metal salts of naphthenic acid (for example, , Calcium salt, cobalt salt, manganese salt, lead salt, zinc salt, etc.), resinic acid metal salt (eg calcium salt, cobalt salt, manganese lead salt, zinc salt etc.), polyacrylic acid metal salt (eg sodium salt) Etc.), polymethacrylic acid metal salt (for example, sodium salt), polymaleic acid metal salt (for example, sodium salt), acrylic acid-maleic acid copolymer metal salt (for example, sodium salt), polystyrene sulfonate metal Anionic organic dispersants such as salts (for example, sodium salts) and the like, and cationic organic dispersants such as quaternary ammonium salts 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 as a toner composed of toner particles having a substantially spherical shape, a uniform shape and a uniform size.

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 more reliably preventing the dispersoids from binding (aggregating) in the aqueous emulsion.
The average particle size of the dispersoid in the aqueous emulsion is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.1 to 3 μm. As a result, it is possible to more reliably prevent the dispersoids from binding (aggregating) in the aqueous emulsion, and to optimize the size of the finally obtained toner particles. In the present specification, the “average particle diameter” refers to a volume-based average particle diameter.

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>
The aqueous emulsion obtained as described above may be used as it is in the aqueous dispersion medium removal step described later, but in the present embodiment, the liquid dispersoid is dispersed in the aqueous dispersion medium. The aqueous suspension 3 in which the solid dispersoid 31 is dispersed in the dispersion medium (aqueous dispersion medium) 32 is obtained from the aqueous emulsion, and the aqueous suspension 3 is subjected to the aqueous dispersion medium removal step.

Hereinafter, a method for preparing the aqueous suspension 3 will be described in detail.
The aqueous suspension 3 can be prepared by removing the solvent constituting the dispersoid from the aqueous emulsion.
The solvent can be removed by, for example, heating (heating) the aqueous emulsion or placing it in a reduced-pressure atmosphere, but it is preferable to remove the solvent by heating the aqueous emulsion under reduced pressure. . Thereby, the aqueous suspension 3 in which the dispersion of the size and shape of the dispersoid 31 is particularly small can be obtained relatively easily. Further, by removing the solvent as described above, deaeration treatment can be performed along with the removal of the solvent. Thereby, the dissolved amount of the gas in the aqueous suspension 3 can be reduced, and the dispersion medium 32 is removed from the droplet 9 of the aqueous suspension 3 in the dispersion medium removing unit M3 of the dry fine particle manufacturing apparatus M1. At this time, it is possible to effectively prevent bubbles and the like from being generated in the aqueous suspension 3. As a result, it is possible to more effectively prevent the irregularly shaped toner particles (hollow particles, missing particles, etc.) from being mixed into the finally obtained liquid developer.

When the aqueous emulsion is heated (warmed), the heating temperature is preferably 30 to 110 ° C, more preferably 40 to 100 ° C. When the heating temperature is a value within the above range, the generation of the irregularly shaped dispersoid 31 is sufficiently prevented (the solvent is surely prevented from evaporating (boiling) from the dispersoid of the aqueous emulsion). However, the solvent can be removed quickly.
Further, when the aqueous emulsion is placed in a reduced pressure atmosphere, the pressure of the atmosphere in which the aqueous emulsion is placed is preferably 0.1 to 50 kPa, and more preferably 0.5 to 5 kPa. When the pressure of the atmosphere in which the aqueous emulsion is placed is a value within the above range, the generation of the irregularly shaped dispersoid 31 is sufficiently prevented (the solvent rapidly vaporizes (boils from the inside of the aqueous emulsion dispersoid) The solvent can be removed quickly, while reliably preventing).

The removal of the solvent may be performed so long as the dispersoid is in a solid state, and may not remove substantially all of the solvent contained in the aqueous emulsion.
The average particle size of the dispersoid 31 in the aqueous suspension 3 is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.1 to 3 μm. As a result, it is possible to more reliably prevent dispersoids from being bonded (aggregated) and to optimize the size of the toner particles finally obtained.

<Aqueous dispersion medium removal process>
Next, dry fine particles corresponding to the dispersoid of the aqueous dispersion (aqueous suspension 3) are obtained by removing the aqueous dispersion medium from the aqueous dispersion (aqueous suspension 3) (aqueous dispersion medium removal step). . The dry fine particles thus obtained correspond to the toner particles of the liquid developer.
The removal of the aqueous dispersion medium may be performed by any method, but it is preferable to intermittently discharge droplets of the dispersion liquid (aqueous dispersion liquid) in which the dispersoid is dispersed in the aqueous dispersion medium. Thereby, the aqueous dispersion medium can be removed more efficiently while effectively preventing dispersoid aggregation and the like, and the productivity of the liquid developer is improved. Further, by removing the aqueous dispersion medium by intermittently discharging droplets of the aqueous dispersion liquid, even when a part of the solvent remains in the preparation of the aqueous suspension described above, This remaining solvent can be efficiently removed together with the aqueous dispersion medium.
In particular, in this embodiment, the aqueous dispersion medium is removed using a dry fine particle production apparatus (toner particle production apparatus) as shown in FIGS.

[Dry particle production equipment]
As shown in FIG. 2, the dry fine particle production apparatus (toner particle production apparatus) M1 includes a head unit M2 that intermittently ejects the aqueous suspension (aqueous dispersion) 3 as droplets 9 as described above, An aqueous suspension supply unit (aqueous dispersion supply unit) M4 that supplies the aqueous suspension 3 to the head unit M2, and a droplet-shaped (particulate) aqueous suspension 3 (liquid) discharged from the head unit M2. A dispersion medium removing unit M3 that removes the dispersion medium 32 while transporting the droplets 9) to form dry fine particles (toner particles) 4, and a recovery unit M5 that collects the produced dry fine particles (toner particles) 4. ing.

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

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

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

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

Examples of such a material having liquid repellency include fluorine resins such as polytetrafluoroethylene (PTFE), silicone materials, and the like.
As shown in FIG. 3, the piezoelectric element M22 includes a lower electrode (first electrode) M221, a piezoelectric body M222, and an upper electrode (second electrode) M223 that are stacked in this order. In other words, the piezoelectric element M22 has a configuration in which the piezoelectric body M222 is interposed between the upper electrode M223 and the lower electrode M221.

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

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

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

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

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

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

  Further, the aqueous suspension 3 discharged from the head M2 may be cooled in advance. By cooling the aqueous suspension 3 in this manner, for example, unintentional evaporation (volatilization) of the dispersion medium 32 from the aqueous suspension 3 in the vicinity of the discharge unit M23 can be effectively prevented. As a result, it is possible to effectively prevent a change in the discharge amount of the aqueous suspension 3 due to the decrease in the opening area of the discharge portion over time, and the variation in size and shape among the particles is particularly small. Toner can be obtained.

Moreover, although the discharge amount for one drop of the aqueous suspension 3 is slightly different depending on the content of the dispersoid 31 in the aqueous suspension 3, it is preferably 0.05 to 500 pl, 0.5 to More preferably, it is 50 pl. By setting the discharge amount of one drop of the aqueous suspension 3 to a value in such a range, the dried fine particles 4 to be formed can have an appropriate particle size.
Further, the average particle diameter of the droplets 9 ejected from the head part M2 is slightly different depending on the content of the dispersoid 31 in the aqueous suspension 3, but is preferably 1.0 to 100 μm. More preferably, it is ˜50 μm. By setting the average particle diameter of the droplets 9 to a value in such a range, the formed dry fine particles 4 can have an appropriate particle diameter.

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

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

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

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

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

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

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

The dispersion medium removing unit M3 is configured by a cylindrical housing M31. For the purpose of keeping the temperature in the dispersion medium removal unit M3 within a predetermined range, for example, a heat source or a cooling source is installed inside or outside the housing M31, or a flow path for the heat medium or the cooling medium is formed in the housing M31. It may be a jacket.
In the illustrated configuration, the pressure in the housing M31 is adjusted by the pressure adjusting means M12. Thus, by adjusting the pressure in the housing M31, the dry fine particles 4 can be formed more efficiently, and as a result, the productivity of the liquid developer is improved. In the configuration shown in the figure, the pressure adjusting means M12 is connected to the housing M31 by a connecting pipe M121. Further, an enlarged diameter portion M122 having an enlarged inner diameter is formed in the vicinity of an end portion of the connection pipe M121 connected to the housing M31, and a filter M123 for preventing the suction of the dry fine particles 4 and the like is further provided. ing.

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

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

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

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

<Encapsulation of oxidation polymerization inhibitor>
Next, the encapsulation of the oxidation polymerization accelerator will be described.
The encapsulation of the oxidation polymerization accelerator can be performed, for example, as follows.
First, an oxidation polymerization accelerator is prepared.
Next, the oxidative polymerization accelerator is dissolved in a solvent.
Such a solvent is not particularly limited as long as the oxidative polymerization accelerator is soluble, and examples thereof include inorganic solvents such as carbon disulfide and carbon tetrachloride, methyl ethyl ketone (MEK), and methyl isopropyl ketone (MIPK). , Ketone solvents such as 2-heptanone, alcohol solvents such as pentanol, n-hexanol, 1-octanol and 2-octanol, ether solvents such as diethyl ether and anisole, hexane, pentane, heptane, cyclohexane, octane, Aliphatic hydrocarbon solvents such as isoprene, aromatic hydrocarbon solvents such as toluene, xylene, benzene, ethylbenzene and naphthalene, aromatic heterocyclic compounds solvents such as furan and thiophene, halogen compound solvents such as chloroform, acetic acid Ethyl, isopropyl acetate, isobutyl acetate, Examples include organic solvents such as ester solvents such as ethyl crylate, nitrile solvents such as acrylonitrile, nitro solvents such as nitromethane and nitroethane, and a mixture of one or more selected from these. be able to.

Next, a porous material such as hydrophilic silica, hydrophilic alumina, hydrophilic titanium oxide or the like is added to the obtained solution, and the solution is adsorbed on the porous material.
Next, the porous body on which the solution is adsorbed and a polyether such as polyethylene glycol or polypropylene glycol are mixed while heating.
The mixing ratio of the porous body and the polyether is preferably about 1: 0.5 to 1:10, more preferably about 1: 1 to 1: 5, by weight.

Moreover, it is preferable that the temperature at the time of mixing a porous body and polyether is 5-80 degreeC, and it is more preferable that it is 20-80 degreeC.
Next, after the obtained mixture is sufficiently dispersed in the petroleum-based hydrocarbon, it is cooled and the polyether is deposited on the surface of the porous body. Thereby, a polyether film is formed on the surface of the porous body.
Then, the encapsulated oxidative polymerization accelerator is obtained by filtering to remove petroleum hydrocarbons. The oxidative polymerization accelerator encapsulated in this way has a higher dispersibility in unsaturated fatty acid glycerides.

<Dispersing process>
Next, the dried fine particles 4 obtained as described above and the encapsulated oxidative polymerization accelerator are dispersed in the insulating liquid described above (dispersing step). Thereby, a liquid developer is obtained.
The dry fine particles 4 may be dispersed in the insulating liquid by any method, but it is preferable to add the dry fine particles 4 to the stirred insulating liquid. Thus, the liquid developer obtained can stably maintain a good dispersion state of the toner particles for a long period of time while preventing unintentional aggregation of the dry fine particles 4 at the time of adjusting the liquid developer. it can.

<Liquid developer>
The liquid developer obtained as described above has small variations in the shape and size of the toner particles. Therefore, such a liquid developer easily migrates in the insulating liquid (in the liquid developer), and is advantageous for high-speed development. In addition, since the variation in the shape and size of the toner particles is small and the insulating liquid as described above is used, the toner particles are excellent in dispersibility, and the toner particles settle in the liquid developer. Floating and the like are effectively prevented. Therefore, such a liquid developer is particularly excellent in storage stability.

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

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

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

Further, after the transfer of the toner image from the photoconductor to the intermediate transfer roller, the photoconductor is neutralized by the neutralizing light P21, and the residual transfer toner remaining on the photoconductor is a cleaning made of urethane rubber or the like. It is removed by the blade P22.
Similarly, residual toner remaining on the intermediate transfer roller P18 after transfer from the intermediate transfer roller P18 to the information recording medium P20 is removed by a cleaning blade P23 made of urethane rubber or the like.

After the toner image formed on the photoreceptor P2 is transferred to the intermediate transfer roller P18, a transfer current is passed through the secondary transfer roller P19, and the information recording medium P20 such as paper passing between them. The toner image on the information recording medium P20 such as paper is fixed using the fixing device shown in FIG.
FIG. 5 shows an example of a non-contact type image forming apparatus to which the liquid developer of the present invention is applied. In the non-contact method, the developing roller P13 is provided with a charging blade P24 made of a phosphor bronze plate having a thickness of 0.5 mm. The charging blade P24 has a function of making frictional charging in contact with the liquid developer layer, and since the application roller P12 is a gravure roll, a developer layer corresponding to the unevenness of the surface of the gravure roll is formed on the development roller P13. Therefore, it functions to uniformly level the unevenness, and the arrangement direction may be either the counter direction or the trail direction with respect to the rotation direction of the developing roller, and may be a roller shape instead of a brate shape.

Further, an interval of 200 μm to 800 μm is provided between the developing roller P13 and the photosensitive member P2, and a frequency of 500 to 3000 Vpp superimposed on a direct current voltage of 200 to 800 V is applied between the developing roller P13 and the photosensitive member P2. An AC voltage of 50 to 3000 Hz is preferably applied. The rest is the same as the image forming apparatus described with reference to FIG.
In FIGS. 4 and 5, image formation using a single color liquid developer has been described. However, when an image is formed using a plurality of color toners, each color image is formed using a plurality of color developing devices. Thus, a color image can be formed.

  FIG. 6 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. Thereby, although the thicknesses of the elastic bodies F1c and 2c are different, 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.

  The fixing temperature for fixing the unfixed toner image is preferably 100 to 200 ° C, more preferably 100 to 180 ° C. At such a fixing temperature, the function of the antioxidant can be effectively reduced, and the oxidative polymerization reaction of the unsaturated fatty acid glyceride by the oxidative polymerization accelerator when oxygen is supplied is more efficiently advanced. be able to. As a result, the fixing strength of the toner can be improved more effectively.

As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
For example, the liquid developer of the present invention is not limited to the one manufactured by the method described above, and may be manufactured by any method. For example, in an unsaturated fatty acid glyceride, the pulverized product as described above may be heated and dispersed, cooled, and then added by adding an oxidative polymerization accelerator or an antioxidant. .

The method for encapsulating the oxidation polymerization accelerator is not limited to the method described above.
Moreover, each part which comprises a dry fine particle manufacturing apparatus can also be substituted with the arbitrary things which exhibit the same function, or can add another structure.
Further, the liquid developer of the present invention is not limited to those applied to the image forming apparatus as described above.

In the above-described embodiment, the configuration in which the encapsulated oxidative polymerization accelerator is dispersed in the insulating liquid has been described. However, the present invention is not limited to this. For example, the encapsulated oxidation polymerization accelerator may be contained in the toner particles. It may adhere to the toner particle surface. When adhering to the surface of the toner particles, the unsaturated fatty acid glyceride can be more reliably cured when fixing.
The unsaturated fatty acid glyceride used in the present invention may be synthesized.

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

As shown in FIG. 7, an acoustic lens (concave lens) M25 may be installed in the head portion M2. By installing such an acoustic lens M25, for example, the pressure pulse (vibration energy) generated by the piezoelectric element M22 can be converged by the pressure pulse converging unit M26 in the vicinity of the ejection unit M23. As a result, the vibration energy generated by the piezoelectric element M22 can be efficiently used as energy for discharging the aqueous suspension 3. Therefore, even if the aqueous suspension 3 stored in the dispersion liquid storage unit M21 has a relatively high viscosity, it can be reliably discharged from the discharge unit M23. Further, even if the aqueous suspension 3 stored in the dispersion liquid storage unit M21 has a relatively large cohesive force (surface tension), it can be discharged as fine droplets. In addition, the particle size of the dry fine particles (toner particles) 9 can be controlled to a relatively small value.
Thus, by adopting the configuration as shown in the figure, the dry fine particles 4 can be formed in a desired shape, even when a higher viscosity material or a material having a high cohesive force is used as the aqueous suspension 3. Since the size can be controlled, the range of material selection is particularly wide, and a toner having desired characteristics can be obtained more easily.

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

The acoustic lens is not limited to a concave lens, and for example, a Fresnel lens, an electronic scanning lens, or the like may be used.
Furthermore, as shown in FIGS. 8 to 10, 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 toner component is described as a solid component contained in the dispersoid. However, at least a part of the toner component may be contained in the dispersion medium.
In the above-described embodiment, the dispersion liquid (aqueous suspension) is intermittently ejected from the head portion by the piezoelectric pulse. However, another method is used as the dispersion liquid ejection method (injection method). You can also. For example, as a method for discharging (injecting) the dispersion liquid, a method such as a spray drying method or a so-called bubble jet (“Bubble Jet” is a registered trademark) method is used, and “the dispersion liquid is pressed against a smooth surface with a gas flow. A method of injecting a dispersion into droplets using a nozzle that is thinly stretched to form a thin laminar flow and ejects the thin laminar flow as fine droplets away from the smooth surface (Japanese Patent Application No. 2002-321889). Or the like) ”or the like. The spray drying method is a method of obtaining liquid droplets by spraying (spraying) a liquid (dispersion) using a high-pressure gas. Moreover, as a method to which a so-called bubble jet (“bubble jet” is a registered trademark) method is applied, a method described in the specification of Japanese Patent Application No. 2002-169348 can be cited. That is, as a method for ejecting (injecting) the dispersion liquid, a “method for intermittently ejecting the dispersion liquid from the head portion by a change in gas volume” can be applied.

Further, the formation of the dry fine particles may not be performed by discharging a dispersion liquid (aqueous suspension). For example, by filtering an aqueous suspension, fine particles corresponding to the dispersoid may be filtered off, and this may be used as dry fine particles.
Further, in the above-described embodiment, it has been described that dry fine particles having a size and shape corresponding to each dispersoid in the aqueous suspension are obtained. However, the dry fine particles are, for example, a plurality of dispersions of the aqueous suspension. Aggregates formed by agglomerating (bonding) fine particles corresponding to the quality may be used.

In the above-described embodiment, the aqueous emulsion is prepared using the pulverized product of the kneaded product, but the pulverizing step of the kneaded product may be omitted.
Moreover, the preparation method of an aqueous emulsion and aqueous suspension is not limited to the method as mentioned above. For example, the 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 aqueous suspension is once obtained using the aqueous emulsion, and then the dry fine particles are produced using the aqueous suspension. However, the aqueous suspension is used. Alternatively, a configuration in which dry fine particles are obtained directly from an aqueous emulsion may be used. For example, dry fine particles may be obtained by discharging an aqueous emulsion into droplets and removing the dispersion medium together with the solvent in the dispersion medium from the droplets.

[1] Production of liquid developer (Example 1)
[Preparation of dry fine particles]
First, an epoxy resin as a binder resin (softening temperature: 128 ° C.): 80 parts by weight and a cyan pigment as a colorant (Pigment Blue 15: 3 manufactured by Dainichi Seika Co., Ltd.): 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 mixture was treated with an ultrasonic homogenizer (output: 400 μA) for 1 hour to dissolve the epoxy resin of the kneaded product. A solution was obtained. 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., Ltd.).
The above solution (a kneaded toluene solution) was dropped into the agitated aqueous liquid. As a result, an aqueous emulsion in which the dispersoid having an average particle diameter of 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 (solid fine particles) dispersed in the suspension was 1.2 μm. The average particle size of the dispersoid was measured using a laser diffraction / scattering particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

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

  For the discharge of the aqueous suspension, the temperature of the dispersion liquid in the head part is 25 ° C., the frequency of the piezoelectric body is 10 kHz, the initial speed of the dispersion liquid discharged from the discharge part is 3 m / second, and the aqueous suspension is discharged from the head part. It was performed in a state where the discharge amount of one drop of the turbid liquid was adjusted to 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, thereby preventing the aqueous suspension (dry fine particles) from adhering to the inner wall.
In the dispersion medium removing section, the dispersion medium was removed from the discharged aqueous suspension, and a large number of dry fine particles (toner particles) having a shape and size corresponding to each dispersoid were formed.
The dry fine particles formed in the dispersion medium removing unit were collected with a cyclone to obtain dry fine particles.

[Encapsulation of oxidative polymerization accelerator]
On the other hand, an encapsulated oxidation polymerization accelerator was prepared as follows.
First, 10 g of zinc octylate as an oxidative polymerization accelerator was dissolved in 15 ml of acetone, and the obtained solution was adsorbed on porous hydrophilic silica gel to obtain a core material.
Next, 10 g of the obtained core material and 20 g of polyethylene glycol (PEG) were heated and mixed to obtain a mixture.
Next, this mixture was put into 400 ml of AF6 Solvent manufactured by Nisseki Mitsubishi Corporation and sufficiently dispersed with a homomixer, and then slowly cooled to deposit PEG.
Thereafter, the solvent was removed by filtration to obtain an encapsulated oxidation polymerization accelerator.

[Preparation of insulating liquid]
On the other hand, an insulating liquid was prepared as follows.
First, sardine oil: 130 parts by volume was charged into the flask, and then boiled water: 100 parts by volume was poured into the flask and the flask was stoppered.
Next, the flask was shaken to mix unrefined sardine oil and boiling water.

Next, the flask was allowed to stand until the mixed liquid in the flask was separated into three layers.
After complete separation was confirmed, the flask was transferred to a freezer and left for 24 hours.
Thereafter, the components that were not frozen were transferred to another flask.
The same operation as described above was repeated for the unfrozen component, and the obtained non-frozen component was taken out to obtain a crude oil or fat.

Next, the crude oil and fat obtained as described above: 100 parts by volume and the activated clay mainly composed of hydrous aluminum silicate: 35 parts by volume were mixed and stirred in the flask.
Next, the obtained mixture was stored under pressure (0.18 MPa) for 48 hours to completely precipitate the activated clay.
Thereafter, the precipitate was removed to obtain fats and oils mainly composed of unsaturated fatty acid glycerides.

The obtained fats and oils: 500 parts by weight and α-tocopherol (thermal decomposition temperature: 200 ° C. or higher): 5 parts by weight as an antioxidant were mixed to obtain an insulating liquid.
The obtained insulating liquid contains glycerides of oleic acid (main component), eicosapentaenoic acid, palmitoleic acid, docosahexaenoic acid as unsaturated fatty acid glycerides, and the content of unsaturated fatty acid glycerides is 75 wt%. Met. Moreover, the electrical resistance of this insulating liquid at room temperature (20 ° C.) was 2.0 × 10 ¹³ Ωcm. The iodine value of the insulating liquid was 170.

[Dispersion of dry fine particles and oxidative polymerization accelerator]
Insulating liquid obtained as described above: 505 parts by weight, surfactant (dodecyltrimethylammonium chloride): 1 part by weight, encapsulated oxidation polymerization accelerator: 1.25 parts by weight (oxidation polymerization promotion) 1 part by weight) and 75 parts by weight of the above-mentioned dry fine particles were stirred and mixed for 10 minutes with a homomixer (made by Tokushu Kika Kogyo Co., Ltd.) to obtain a liquid developer.

(Examples 2 to 5)
Other than adjusting the content of unsaturated fatty acid glycerides in the insulating liquid as shown in Table 1 by changing the preparation conditions of the insulating liquid using the oxidation polymerization accelerators and antioxidants shown in Table 1 Prepared a liquid developer in the same manner as in Example 1.
(Examples 6 and 7)
In the preparation of the kneaded product, liquid development was performed in the same manner as in Example 1 except that the binder resin shown in Table 1 was used and the contents of the oxidation polymerization accelerator and the antioxidant were shown in Table 1. An agent was prepared.

(Example 8)
In the preparation of the kneaded material, a liquid developer was prepared in the same manner as in Example 6 except that the binder resin shown in Table 1 was used and the insulating liquid prepared as follows was used. did.
First, 130 parts by volume of linseed oil was added to the flask, and then 100 parts by volume of boiled water: 100 parts by volume was poured into the flask to plug the flask.

Next, the flask was shaken to mix unrefined linseed oil and boiling water.
Next, the flask was allowed to stand until the mixed liquid in the flask was separated into three layers.
After complete separation was confirmed, the flask was transferred to a freezer and left for 24 hours.
Thereafter, the components that were not frozen were transferred to another flask.
The same operation as described above was repeated for the unfrozen component, and the obtained non-frozen component was taken out to obtain a crude oil or fat.

Next, the crude oil and fat obtained as described above: 100 parts by volume and the activated clay mainly composed of hydrous aluminum silicate: 35 parts by volume were mixed and stirred in the flask.
Next, the obtained mixture was stored under pressure (0.18 MPa) for 48 hours to completely precipitate the activated clay.
Thereafter, the precipitate was removed to obtain fats and oils mainly composed of unsaturated fatty acid glycerides.

The obtained fats and oils: 500 parts by weight and α-tocopherol (thermal decomposition temperature: 200 ° C. or higher): 5 parts by weight as an antioxidant were mixed to obtain an insulating liquid.
The obtained insulating liquid contains glycerides of α-linolenic acid (main component), oleic acid, and linoleic acid as unsaturated fatty acid glycerides, and the content of unsaturated fatty acid glycerides was 97 wt%. It was. Moreover, the electrical resistance of this insulating liquid at room temperature (20 ° C.) was 2.2 × 10 ¹³ Ωcm. The iodine value of the insulating liquid was 190.

Example 9
A liquid developer was prepared in the same manner as in Example 6 except that the insulating liquid prepared as follows was used.
First, 130 parts by volume of soybean oil was put into a flask, and then 100 parts by volume of boiled water: 100 parts by volume was poured into the flask to plug the flask.

Next, the flask was shaken to mix crude soybean oil and boiling water.
Next, the flask was allowed to stand until the mixed liquid in the flask was separated into three layers.
After complete separation was confirmed, the flask was transferred to a freezer and left for 24 hours.
Thereafter, the components that were not frozen were transferred to another flask.
The same operation as described above was repeated for the unfrozen component, and the obtained non-frozen component was taken out to obtain a crude oil or fat.

Next, the crude oil and fat obtained as described above: 100 parts by volume and the activated clay mainly composed of hydrous aluminum silicate: 35 parts by volume were mixed and stirred in the flask.
Next, the obtained mixture was stored under pressure (0.18 MPa) for 48 hours to completely precipitate the activated clay.
Thereafter, the precipitate was removed to obtain fats and oils mainly composed of unsaturated fatty acid glycerides.

The resulting fat / oil: 500 parts by weight and α-tocopherol as an antioxidant: 5 parts by weight were mixed to obtain an insulating liquid.
The obtained insulating liquid contains glycerides of linoleic acid (main component), oleic acid and α-linolenic acid as unsaturated fatty acid glycerides, and the content of unsaturated fatty acid glycerides was 98 wt%. It was. Moreover, the electrical resistance of this insulating liquid at room temperature (20 ° C.) was 2.5 × 10 ¹³ Ωcm. The iodine value of the insulating liquid was 200.
(Example 10)
A liquid developer was prepared in the same manner as in Example 8 except that the antioxidant shown in Table 1 was used.

(Comparative Example 1)
A liquid developer was produced in the same manner as in Example 1 except that Isopar G was used as the insulating liquid and no oxidation polymerization accelerator was used.
(Comparative Example 2)
A liquid developer was prepared in the same manner as in Example 1 except that the oxidation polymerization accelerator was not used.

(Comparative Example 3)
A liquid developer was prepared in the same manner as in Example 1 except that the oxidation polymerization accelerator was not encapsulated.
(Comparative Example 4)
A liquid developer was prepared in the same manner as in Example 1 except that the antioxidant was not used.

  Table 1 shows the manufacturing conditions of the liquid developer for each of the above Examples and Comparative Examples. In the table, oleic acid is OL, palmitoleic acid is PT, linoleic acid is LN, α-linolenic acid is LL, docosahexaenoic acid is DHA, eicosapentaenoic acid is EPA, zinc octylate is O-Zn, calcium naphthenate N-Ca, cobalt linolenate is L-Co, α-tocopherol is VE, dibutylhydroxytoluene is BHT, butylhydroxyanisole is BHA, and ascorbic acid stearate is VC.

[2] Evaluation Each liquid developer obtained as described above was evaluated for fixing strength, storage stability, and long-term stability.
[2.1] Fixing Strength Using an image forming apparatus as shown in FIG. 4, an image of a predetermined pattern with a liquid developer obtained in each of the above examples and each of the comparative examples was recorded on a recording paper (manufactured by Seiko Epson Corporation, It was formed on fine 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 determined as X -Measured according to "X-Rite model 404" manufactured by Rite Inc, and evaluated according to the following five-step criteria.
A: Image density residual ratio is 95% or more.
A: Image density residual ratio is 90% or more and less than 95%.
○: Image density remaining rate is 80% or more and less than 90%.
Δ: Image density remaining rate is 70% or more and less than 80%.
X: Image density remaining rate is less than 70%.

[2.2] Preservability The liquid developers obtained in the respective Examples and Comparative Examples were allowed to stand for 6 months in an environment at a temperature of 15 to 25 ° C. Thereafter, the state of the toner in the liquid developer was visually confirmed and evaluated according to the following five-step criteria.
A: No floating or coagulation sedimentation of toner particles is observed.
A: Floating toner particles and coagulation sedimentation are hardly observed.
○: Slight floating or coagulation sedimentation of toner particles is observed, but as a liquid developer
There is no problem.
Δ: Floating or coagulating sedimentation of toner particles is clearly observed.
X: Remarkably floating and coagulating sedimentation of toner particles are observed.

[2.3] Long-term stability The liquid developers obtained in the above Examples and Comparative Examples were allowed to stand for 6 months in an environment of 35 ° C. and a relative humidity of 65%. Thereafter, the state of the liquid developer was observed and evaluated according to the following five-step criteria.
A: No thickening / discoloration of the liquid developer is observed.
A: Viscosity / discoloration of the liquid developer is hardly recognized.
○: Slight thickening / discoloration of liquid developer is observed, but no problem as liquid developer
It is the range.
Δ: The thickening / discoloration of the liquid developer is clearly recognized. ×: The thickening / discoloration of the liquid developer is noticeable.

The results are shown in Table 2 together with the average circularity R, circularity standard deviation, number-based average particle diameter, and particle diameter standard deviation of the toner particles. The circularity was measured using a flow type particle image analyzer (FPIA-2000, manufactured by Toa Medical Electronics Co., Ltd.). However, the circularity R is represented by the following formula (I).
R = L ₀ / L ₁ (I)
(Wherein, L ₁ [μm] is the circumference of the projected image of the particle to be measured, and L ₀ [μm] is the circumference of a perfect circle having an area equal to the area of the projected image of the particle to be measured To express.)

As is apparent from Table 2, the liquid developer of the present invention was excellent in fixing strength, storage stability, and long-term stability. On the other hand, satisfactory results were not obtained with the liquid developers of the comparative examples. Since vitamin C has a relatively weaker antioxidant effect than vitamin E, Example 10 has a slightly lower long-term stability than Example 8.
Further, as is clear from Table 2, in all of the liquid developers of the present invention, the toner particles had a large circularity and a small width of the particle size distribution. Further, the variation in the shape of the toner particles (standard deviation of circularity) was small.

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.
Also, the structure near the head of the dry particle manufacturing apparatus is changed from the structure shown in FIG. 3 to the structure shown in FIGS. As a result of production and evaluation, results similar to the above were obtained. Moreover, in the dry particle manufacturing apparatus provided with the head part as shown in FIGS. 7 to 10, even when the diameter of the discharge part is reduced and the concentration of the aqueous suspension is relatively high, the discharge is preferably performed The results were obtained as above. In addition, since a high-concentration aqueous suspension was used, the time required for drying could be shortened, and productivity was improved.

It is a longitudinal cross-sectional view which shows typically an example of a structure of the kneading machine for manufacturing the kneaded material used for preparation of an aqueous emulsion, and a cooler. FIG. 2 is a longitudinal sectional view schematically showing a preferred embodiment of a dry fine particle production apparatus (toner particle production apparatus) used for production of the liquid developer of the present invention. FIG. 3 is an enlarged cross-sectional view of the vicinity of the head portion of the dry particle manufacturing apparatus shown in FIG. 1 is a cross-sectional view illustrating an example of a contact-type image forming apparatus to which a liquid developer of the present invention is applied. 1 is a cross-sectional view illustrating an example of a non-contact type image forming apparatus to which a liquid developer of the present invention is applied. FIG. 3 is a cross-sectional view illustrating an example of a fixing device to which the liquid developer of the present invention is applied. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus. It is a figure which shows typically the other examples of the structure of the head part vicinity of a dry fine particle manufacturing apparatus.

Explanation of symbols

K1 ... kneading machine K2 ... process part K21 ... barrel K22, K23 ... screw K24 ... fixing member K25 ... deaeration port K3 ... head part K31 ... internal space K32 ... extrusion port K33 ... cross-sectional area gradually decreasing part K4 ... feeder K5 ... raw material K6 ... Coolers K61, K62, K63, K64 ... Rolls K611, K621, K631, K641 ... Rotating shafts K65, K66 ... Belt K67 ... Discharge part K7 ... Kneaded product M1 ... Dry particle production device (toner particle production device) M2 ... Head M21 ... Dispersion storage unit M22 ... Piezoelectric element M221 ... Lower electrode M222 ... Piezoelectric body M223 ... Upper electrode M23 ... Discharge unit M24 ... Diaphragm M25 ... Acoustic lens M26 ... Pressure pulse converging unit M3 ... Dispersion medium removing unit M31 ... Housing M311 ... Reduced diameter part M4 ... Aqueous suspension supply part (Aqueous dispersion supply part) 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 Squeezing member P ... pump 3 ... aqueous suspension (aqueous dispersion) 31 ... dispersoid 32 ... dispersion medium (aqueous dispersion medium) 4 ... dry fine particles (toner particles) 9 ... droplet P1 ... image forming apparatus P2 ... photosensitive Body P3 ... Charger P4 ... Exposure P10 ... Developer P11 ... Developer container P12 ... Applying roller P13 ... Developing roller P14 ... Liquid developer coating layer P15 ... Metering blade P16 ... Roller core P17 ... Developing roller cleaning blade P18 ... Intermediate transfer roller P19 ... secondary transfer roller P20 ... information recording medium P21 ... static elimination light P22 ... cleaning Raid P23 ... Cleaning blade P24 ... Charging blade F40 ... Fixing device F1 ... Heat fixing roll (heating roll) F1a ... Column-shaped 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 ... concave F5 ... sheet material F5a ... unfixed toner image F6 ... cleaning member F9 ... spring

Claims (8)

Encapsulated by coating with an insulating liquid mainly containing an unsaturated fatty acid glyceride, toner particles dispersed in the insulating liquid, an antioxidant for preventing oxidation of the unsaturated fatty acid glyceride, and a polyether And a oxidative polymerization accelerator that promotes an oxidative polymerization reaction of the unsaturated fatty acid glyceride.   The liquid developer according to claim 1, wherein the oxidative polymerization accelerator is a fatty acid metal salt.   3. The liquid developer according to claim 1, wherein the content of the oxidative polymerization accelerator in the liquid developer is 0.01 to 10 parts by weight with respect to 100 parts by weight of the unsaturated fatty acid glyceride.   The liquid developer according to any one of claims 1 to 3, wherein the encapsulation is performed by adsorbing the oxidative polymerization accelerator to a porous body and then coating the porous body.   5. The liquid developer according to claim 1, wherein a content of the antioxidant in the insulating liquid is 0.01 to 10 wt%.   The liquid developer according to claim 1, wherein the antioxidant is vitamin C.   The liquid developer according to claim 2, wherein the fatty acid metal salt is zinc octylate. Exposure to form a latent image on the photoreceptor,
Insulating liquid mainly containing unsaturated fatty acid glyceride, toner particles dispersed in the insulating liquid, antioxidant for preventing oxidation of unsaturated fatty acid glyceride , and glyceride encapsulated by coating with polyether Developing the latent image using a liquid developer containing an oxidative polymerization accelerator that promotes the oxidative polymerization reaction of
Transfer the developed image to a recording medium,
An image forming method , wherein the image transferred to the recording medium is heated and pressurized to be fixed on the recording medium .

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