JP5672024B2 - Liquid developer, developer cartridge, image forming method, and image forming apparatus - Google Patents

Description

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

  Patent Document 1 discloses a composition containing a colorant, a monomer having a specific structure or a polymer thereof, and a polyfunctional acrylate monomer or a polymer thereof in an aliphatic hydrocarbon solvent, or a copolymer thereof. An electrophotographic liquid developer is disclosed in which an ultraviolet fixing toner as a main component is dispersed.

  Patent Document 2 discloses a liquid developer in which toner particles mainly composed of a resin material are dispersed in an insulating liquid, and the insulating liquid contains a specific unsaturated fatty acid monoester, and the insulating liquid A liquid developer is disclosed in which the content of the unsaturated fatty acid monoester, the volumetric efficiency of the insulating liquid, and the weight average molecular weight Mw of the resin material are in a specific range.

  Patent Document 3 discloses an electrophotographic liquid development in which toner particles containing at least one thermoplastic resin and an aliphatic polyester oligomer in a specific content ratio are suspended and dispersed in an electrically insulating non-aqueous carrier liquid. Agents are disclosed.

  Patent Document 4 discloses a dry electrostatic image development characterized by comprising an ion-crosslinked amorphous vinyl polymer, a paraffin wax, and an alkylene bis-fatty acid amide wax having a specific structure. Toner is disclosed.

Japanese Patent Publication No. 6-25875 JP 2008-26571 A Japanese Patent Laid-Open No. 3-271552 JP-A-1-161255

  An object of the present invention is to provide a liquid developer that can achieve both a low minimum fixing temperature and an improvement in storage stability of an image obtained.

The above problem is solved by the following means. That is,
The invention according to claim 1
Carrier liquid,
Toner particles dispersed in the carrier liquid, comprising a binder resin and a radical polymerizable compound, the radical polymerizable compound being a liquid compound at 25 ° C., and 50 parts by mass of the carrier liquid; Toner particles that are poorly soluble compounds in which at least part of the radical polymerizable compound is not dissolved in the carrier liquid under a condition in which 1 part by mass of the radical polymerizable compound is mixed at 25 ° C .;
The binder resin is a liquid developer containing a styrene thermoplastic resin and a styrene thermoplastic elastomer resin .

The invention according to claim 2
The liquid developer according to claim 1, wherein the radical polymerizable compound has two or more polymerizable groups in one molecule.

The invention according to claim 3
The liquid developer according to claim 1, further comprising a polymerization initiator.

The invention according to claim 4
A developer cartridge containing the liquid developer according to any one of claims 1 to 3.

The invention according to claim 5
A latent image forming step of forming a latent image on the surface of the latent image holding member;
4. The toner developed by the liquid developer according to claim 1, wherein the latent image formed on the surface of the latent image holding member is held on the surface of the developer holding member. 5. A development process for forming an image;
A transfer step of transferring the toner image formed on the surface of the latent image holding member onto a recording medium;
A fixing step of fixing the toner image transferred to the recording medium to the recording medium to form a fixed image;
A stimulus applying step of applying a stimulus to the fixed image;
And an image forming method.

The invention according to claim 6
6. The image forming method according to claim 5, further comprising a polymerization initiator adding step of adding a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied by the stimulus applying step. .

The invention according to claim 7 provides:
A latent image carrier,
Latent image forming means for forming a latent image on the surface of the latent image holder;
The liquid developer according to any one of claims 1 to 3, wherein the liquid developer according to any one of claims 1 to 3 is contained, the developer holding body is provided, and the latent image formed on the surface of the latent image holding body is Developing means for developing with the liquid developer held on the surface of the developer holder to form a toner image;
Transfer means for transferring the toner image formed on the surface of the latent image holding member onto a recording medium;
Fixing means for fixing the toner image transferred to the recording medium to the recording medium to form a fixed image;
A stimulus applying means for applying a stimulus to the fixed image;
An image forming apparatus having

The invention according to claim 8 provides:
The image forming apparatus according to claim 7, further comprising a polymerization initiator adding unit that adds a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied by the stimulus applying unit. .

  According to the first aspect of the present invention, the minimum fixing temperature is kept low and the storability of the obtained image is improved as compared with the case where the toner particles do not contain the radical polymerizable compound.

  According to the second aspect of the present invention, the storage stability of the obtained image is improved as compared with the case where the radical polymerizable compound has one polymerizable group in one molecule.

  According to the third aspect of the present invention, an image with good storability can be formed without separately providing a polymerization initiator addition step as compared with the case where the liquid developer does not contain a polymerization initiator.

  According to the inventions according to claims 4 to 8, the minimum fixing temperature is suppressed and the storage stability of the obtained image is improved as compared with the case where the toner particles do not contain the radical polymerizable compound. It is compatible.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.

[Liquid developer]
The liquid developer according to the exemplary embodiment includes a carrier liquid and toner particles dispersed in the carrier liquid, and the toner particles include a binder resin and a radical polymerizable compound. The radical polymerizable compound is a compound that is liquid at 25 ° C., and the radical polymerizable compound is mixed under conditions where 50 parts by mass of the carrier liquid and 1 part by mass of the radical polymerizable compound are mixed at 25 ° C. At least a part of the compound is insoluble and does not dissolve in the carrier liquid.
Hereinafter, “liquid at 25 ° C.” may be referred to as “liquid”, and a compound that is liquid at 25 ° C. may be referred to as “liquid compound”. In addition, it indicates that at least a part of the radical polymerizable compound does not dissolve in the carrier liquid under the condition that 50 parts by mass of the carrier liquid and 1 part by mass of the radical polymerizable compound are mixed at 25 ° C. It may be expressed as “the polymerizable compound is hardly soluble in the carrier liquid”.

  Here, whether or not the radical polymerizable compound is hardly soluble in the carrier liquid is confirmed as follows. Specifically, for example, a mixed solution obtained by mixing 50 parts by mass of the carrier liquid and 1 part by mass of the radical polymerizable compound at 25 ° C. is stirred for 10 minutes to determine whether the radical polymerizable compound remains undissolved. The case where it is judged visually and the undissolved residue is visually confirmed is defined as “slightly soluble”.

The liquid developer according to the exemplary embodiment has the above-described configuration, so that the minimum fixing temperature can be suppressed lower and the storability of the obtained image can be improved as compared with the case where the toner particles do not contain the radical polymerizable compound. Are compatible. The reason is not clear, but is presumed as follows.
In the present embodiment, it is considered that the binder resin is plasticized due to the plasticizing effect of the radical polymerizable compound by including a liquid radical polymerizable compound in the toner particles. Therefore, as compared with the case where the radical polymerizable compound is not included (that is, the case where the radical polymerizable compound is not included or the case where a solid radical polymerizable compound is included instead of liquid), the fixing is performed at a lower temperature. Therefore, it is considered that the lower limit value of the temperature range at which the image is fixed (hereinafter sometimes referred to as “minimum fixing temperature”) is lowered.

Moreover, in this embodiment, since the radically polymerizable compound that is hardly soluble in the carrier liquid is included, for example, it is not hardly soluble in the carrier liquid (50 parts by mass of the carrier liquid and 1 part by mass of the radically polymerizable compound are added at 25 ° C. Compared to the case where there is no radically polymerizable compound that does not dissolve in the carrier liquid when mixed, the radically polymerizable compound is likely to be present at a high concentration in the toner particles, and the above plasticizing effect is likely to be obtained. .
Specifically, when a radical polymerizable compound that is not hardly soluble in the carrier liquid is used, the radical polymerizable compound can be dispersed by dispersing the toner particles in the carrier liquid even if the radical polymerizable compound is contained in the toner particles in the manufacturing process. It is considered that the compound is easily dissolved in the carrier liquid. Therefore, it is considered that the radical polymerizable compound is hardly present in the toner particles, and the plasticizing effect by the radical polymerizable compound is hardly obtained.

  In contrast, in the present embodiment, since a radically polymerizable compound that is hardly soluble in the carrier liquid is used, the radically polymerizable compound can be used as a carrier even if the toner particles previously incorporated with the radically polymerizable compound are dispersed in the carrier liquid. It is considered difficult to dissolve in the liquid. In this embodiment, since a radically polymerizable compound that is hardly soluble in the carrier liquid is used, even if the radically polymerizable compound is added after the toner particles are dispersed in the carrier liquid, the radically polymerizable compound in the carrier liquid is not changed. It is considered that the toner particles are easily absorbed. In this way, by using a radically polymerizable compound that is hardly soluble in the carrier liquid, it is easier for the radically polymerizable compound to be present in the toner particles than when a radically polymerizable compound that is not hardly soluble in the carrier liquid is used. Therefore, it is considered that the plasticizing effect is easily obtained.

In the present embodiment, since the radically polymerizable compound is contained in the toner particles, it is considered that the radically polymerizable compound reacts by generating a radical by applying a stimulus to the image and the image is cured. Therefore, in this embodiment, it is considered that an image having good storage stability is formed as compared with a case where the radical polymerizable compound is not included (for example, when a plasticizer other than the radical polymerizable compound is used).
As described above, in this embodiment, when the toner particles do not contain the radical polymerizable compound, the minimum fixing temperature is kept low and the preservation of the obtained image is improved. Guessed.

  The stimulus imparted to the image is selected according to the radical polymerizable compound used, and is not limited as long as the radical polymerization reaction of the radical polymerizable compound occurs. Specifically, for example, Examples include radiation and heat. Examples of radiation include α rays, γ rays, X rays, ultraviolet rays, visible rays, and electron beams. Among these, the form using ultraviolet rays or visible rays is considered to be low in cost and high in safety. Moreover, when using an ultraviolet-ray, visible light, etc. as a radiation, you may use together the polymerization initiator and sensitizer for starting superposition | polymerization of a radically polymerizable compound.

  In the present embodiment, by using a radically polymerizable compound having two or more polymerizable groups in one molecule (hereinafter sometimes referred to as “bifunctional or more radically polymerizable compound”), it is polymerizable in one molecule. Compared to the case of using a radically polymerizable compound having one group, the storability of the obtained image is further improved. The reason for this is not clear, but the radical polymerizable compound has two or more polymerizable groups, so there are more reactive points of the radical polymerizable compound than in the case of one polymerizable group, so the image is stimulated. This is presumably because it is easier to cure and a strong image can be easily obtained.

Further, in this embodiment, since the liquid developer contains a polymerization initiator, an image having good storage stability can be obtained without separately providing a polymerization initiator addition step as compared with the case where the liquid developer does not contain a polymerization initiator. And the image forming process is simplified.
Hereinafter, the components constituting the liquid developer will be described in more detail.

<Toner particles>
As described above, the toner particles include at least a binder resin and a radical polymerizable compound, and may include other components such as a colorant, a release agent, and a polymerization initiator as necessary.

-Binder resin-
The binder resin is not particularly limited. For example, polyester, polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-anhydrous. A maleic acid copolymer, polyethylene, polypropylene, etc. are mentioned. Furthermore, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, and paraffin wax may be used. As the binder resin, the above resins may be used alone, or two or more kinds of resins may be mixed and used.
Examples of the form in which two or more kinds of resins are mixed and used include, for example, a mixture of a thermoplastic resin and a thermoplastic elastomer, and more specifically, for example, a styrene thermoplastic resin and a styrene thermoplastic elastomer resin. And a mixture thereof.

  The styrene-based thermoplastic resin is a thermoplastic resin having a repeating unit derived from a monomer having a styrene skeleton (hereinafter sometimes referred to as “styrene-based monomer”). Here, “a repeating unit derived from a styrenic monomer” means a repeating unit generated as a result of the reaction of a styrene monomer among the repeating units constituting the polymer. The same applies to repeating units derived from other monomers.

  Examples of the styrene monomer include styrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-ter-butylstyrene, pn-hexylstyrene, and pn-octyl. Styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene and the like can be mentioned.

  The styrenic thermoplastic resin may be a copolymer of a styrene monomer and another monomer. Other monomers include, for example, monomers having an acrylate structure (hereinafter sometimes referred to as “acrylate monomers”) and other monomers having a vinyl group (hereinafter “vinyl”). And may be referred to as “system monomers”).

  Specific examples of the acrylate monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, (meth) acrylic acid. In addition to alkyl esters of (meth) acrylic acid such as isobutyl, n-octyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl acrylate, stearyl (meth) acrylate, 2-chloroethyl acrylate, ( (Meth) acrylic acid phenyl, α-methyl chloroacrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, glycidyl (meth) acrylate, Dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, bisugu Glycidyl methacrylate, polyethylene glycol dimethacrylate, etc. methacryloxyethyl phosphate and the like, may be used alone or in combination of two or more monomers. In addition, the above “(meth) acryl” means either or both of acrylic and methacrylic.

  Examples of other vinyl monomers include olefin monomers such as ethylene, propylene, butylene, butadiene, and isoprene, and vinyl ester monomers such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl benzoate. Acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid and crotonic acid and α- or β-alkyl derivatives thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid and the like Examples include ester derivatives or diester derivatives; succinic acid mono (meth) acryloyloxyethyl ester, (meth) acrylonitrile, acrylamide, and the like.

As a weight average molecular weight (Mw) of a thermoplastic resin, the range of 150,000 or more and 500,000 or less is mentioned, for example.
Moreover, as molecular weight distribution (Mw / Mn) of a thermoplastic resin, the range of 2-20 is mentioned, for example.
The thermoplastic resin may have a plurality of peaks and shoulders in the molecular weight distribution measured by gel permeation chromatography (GPC).

  The weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120 as a measuring device and a Tosoh column / TSKgel Super HM-M (15 cm). The weight average molecular weight is calculated from the measurement result using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample. The same applies to the measurement of the weight average molecular weight. The number average molecular weight (Mn) is also measured in the same manner as the weight average molecular weight (Mw), and the molecular weight distribution (Mw / Mn) is calculated from these values.

  The styrenic thermoplastic elastomer resin is a thermoplastic elastomer resin having a repeating unit derived from at least a styrenic monomer. Examples of the thermoplastic elastomer resin include those having rubber properties at normal temperature (for example, 25 ° C.) and softening properties similar to thermoplastics at high temperatures.

  Specific examples of the styrene thermoplastic elastomer resin include, for example, a block copolymer of the styrene monomer and the olefin monomer, and more specifically, for example, polystyrene-polybutadiene. Polystyrene, polystyrene-polybutadiene / butylene-polystyrene, polystyrene-polyethylene / butylene-polystyrene, polystyrene-polyisoprene-polystyrene, polystyrene-hydrogenated polybutadiene-polystyrene, polystyrene-hydrogenated polyisoprene-polystyrene, polystyrene-hydrogenated poly (isoprene). / Butadiene) -polystyrene and the like.

In the above specific examples, for example, “polystyrene-polybutadiene / butylene-polystyrene” is a block copolymer in which a polystyrene block, a polybutadiene block, and a polystyrene block are combined in this order, and the butadiene block is partially Indicates a hydrogenated structure. That is, the above-mentioned “polybutadiene / butylene” means a block in which a butadiene portion and a butylene portion hydrogenated with butadiene are mixed.
In the above specific examples, for example, “hydrogenated polybutadiene” indicates that hydrogen is added to the double bond of polybutadiene.

Moreover, in these block copolymers, you may use the block copolymer which introduce | transduced the polar group into the soft segment part pinched | interposed into polystyrene.
Examples of the polar group include a hydroxyl group, a carboxyl group, an amino group, and an acyl group.

Examples of the weight average molecular weight of the styrenic thermoplastic elastomer resin include a range of 30,000 to 300,000.
Examples of commercially available styrene-based thermoplastic elastomer resins include Tuftec M1911, Tuftec M1943, Tuftec MP10, Asaprene T439, Tufrene A, Kuraray DYNARON 8630P manufactured by Asahi Kasei Corporation.

  When the binder resin is a mixture of a thermoplastic resin and a thermoplastic elastomer resin, the content of the thermoplastic resin is, for example, 50% by mass or more and 90% by mass or less, and 50% by mass with respect to the entire toner particles. More than 70 mass% may be sufficient. The content of the thermoplastic elastomer resin is, for example, from 5% by weight to 50% by weight with respect to the entire toner particles, and may be from 10% by weight to 40% by weight.

-Radically polymerizable compounds-
A radically polymerizable compound is a compound that undergoes a polymerization reaction by radicals generated by stimulation such as radiation, and examples thereof include compounds having an ethylenically unsaturated bond, and specifically include, for example, an ethylenically unsaturated bond. Monomer.
In the liquid developer of this embodiment, the radically polymerizable compound contained in the toner particles is a liquid as described above and a compound that is hardly soluble in the carrier liquid.

Examples of the liquid radical polymerizable compound include the following (meth) acrylate compounds.
Specific examples of the monofunctional (one polymerizable group in one molecule) (meth) acrylate compound include, for example, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, isodecyl (meth) acrylate, stearyl ( (Meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexylglycol (meth) acrylate, 2-chloroethyl (meth) acrylate, butoxymethyl (meth) acrylate, 2, 2,2-tetrafluoroethyl (meth) acrylate, phenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dimethylaminomethyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate Relate, oligoethylene oxide monomethyl ether (meth) acrylate.

  Specific examples of the bifunctional (two polymerizable groups in one molecule) (meth) acrylate compound include, for example, 1,6-hexanediol di (meth) acrylate and 1,10-decandiol di (meth). Acrylate, neopentyl glycol di (meth) acrylate, 2,4-dimethyl-1,5-pentanediol di (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene Glycol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate Rate, oligo propylene glycol di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate.

  Specific examples of trifunctional (three polymerizable groups in one molecule) (meth) acrylate compound include, for example, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, and trimethylolpropane. Alkylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate , Dipentaerythritol propionate tri (meth) acrylate, tri ((meth) acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde modified dimethylolpropane tri (meth) Acrylate, sorbitol tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, ethoxylated glycerin triacrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate.

  Specific examples of tetrafunctional (four polymerizable groups in one molecule) (meth) acrylate compounds include, for example, pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, and ditrimethylolpropane tetra (meth). Examples thereof include acrylates, dipentaerythritol propionate tetra (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and tetramethylolmethane tetra (meth) acrylate.

Specific examples of pentafunctional (5 polymerizable groups in one molecule) (meth) acrylate compounds include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.
Specific examples of hexafunctional (6 polymerizable groups in one molecule) (meth) acrylate compounds include, for example, dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, and phosphazene alkylene oxide modified hexa (Meth) acrylate, captolactone-modified dipentaerythritol hexa (meth) acrylate, and the like.

Among the liquid radically polymerizable compounds, the radically polymerizable compound that is hardly soluble in the carrier liquid is selected according to the carrier liquid to be used.
Specifically, for example, when paraffin oil is used as the carrier liquid, examples of the radically polymerizable compound that is hardly soluble in the carrier liquid include, for example, ethylene oxide-modified bisphenol A diacrylate, propylene oxide-modified bisphenol A diacrylate, Examples include pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

  Examples of the combination of the carrier liquid and the radical polymerizable compound used in the present embodiment include a combination of Moresco White P40 and ethylene oxide-modified bisphenol A diacrylate, a combination of Moresco White P40 and dipentaerythritol hexaacrylate, A combination of Moresco White MT-30P and propylene oxide-modified bisphenol A diacrylate is exemplified.

Only one radical polymerizable compound may be used, or two or more radical polymerizable compounds may be used in combination.
Examples of the content of the radically polymerizable compound with respect to the toner particles include 5% by mass to 70% by mass, and may be 10% by mass to 50% by mass, and may be 10% by mass to 30% by mass. May be.
Examples of the molecular weight of the radical polymerizable compound include a range of 170 to 2000, and may be 250 to 1000.

Whether or not the radically polymerizable compound is contained in the toner particles can be determined, for example, by extracting only the toner particles from the liquid developer and analyzing the obtained toner particles by NMR or the like.
Specifically, for example, only the toner particles are extracted by filtering the liquid developer through a filter that does not pass through the toner particles. Then, after volatilizing the carrier liquid adhering to the surface of the obtained toner particles, the measurement sample is prepared by dissolving in a heavy solvent for measurement, and the components constituting the toner particles are analyzed with a ¹ H-NMR apparatus. .
Further, regarding the content of the radical polymerizable compound contained in the toner particles, the toner particles extracted by the above method are measured by ¹ H-NMR together with the internal standard substance having a known concentration, and separately, the radical polymerization having a known concentration is performed. calculated by comparing the measured value of ^{1 H-NMR} of only sex compound and internal standard.

-Other components-
In addition to the vinyl resin and the styrene thermoplastic elastomer resin, the toner particles may contain other components such as a colorant, a release agent, a polymerization initiator, a charge control agent, silica powder, and a metal oxide as necessary. You may contain. Details of the polymerization initiator will be described later. These other components may be added internally by, for example, kneading into the binder resin, or may be added externally by, for example, performing a mixing process after obtaining toner particles. When the toner particles are transparent toner, it is not necessary to include a colorant.

As the colorant, a known pigment or dye is used. Specific examples include yellow, magenta, cyan, and black pigments shown below.
Examples of the yellow pigment include compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex compounds, methine compounds, and allylamide compounds.
Examples of magenta pigments include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.
Examples of cyan pigments include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like.
Examples of black pigments include carbon black, aniline black, acetylene black, and iron black.

  The release agent is not particularly limited, and examples thereof include plant waxes such as carnauba wax, sugar wax, and wood wax; animal waxes such as beeswax, insect wax, whale wax, and wool wax; And synthetic hydrocarbon waxes such as Fischer-Tropsch wax (FT wax), polyethylene wax, polypropylene wax, and polyester wax. Only one type of release agent may be used, or two or more types may be used.

  There is no restriction | limiting in particular as a charge control agent, A conventionally well-known charge control agent is used. For example, positively chargeable charge control agents such as nigrosine dye, fatty acid-modified nigrosine dye, carboxyl group-containing fatty acid-modified nigrosine dye, quaternary ammonium salt, amine compound, amide compound, imide compound, organometallic compound; oxycarboxylic acid And a negatively chargeable charge control agent such as a metal complex of an azo compound, a metal complex salt dye, or a salicylic acid derivative. Only one type of charge control agent may be used, or two or more types may be used.

  The metal oxide is not particularly limited, and examples thereof include titanium oxide, aluminum oxide, magnesium oxide, zinc oxide, strontium titanate, barium titanate, magnesium titanate, and calcium titanate. Only one type of metal oxide may be used, or two or more types may be used.

-Toner Particle Manufacturing Method-
The method for producing the toner particles used in the present embodiment is not particularly limited. For example, the toner particles are produced by a method for producing pulverized toner particles, in-liquid emulsified dry toner particles, or polymerized toner particles.

Specifically, for example, a binder resin and, if necessary, other additives such as a colorant and a release agent are introduced into a mixing device such as a Henschel mixer and mixed, and this mixture is twin-screw extruded. After melt-kneading with a machine, etc., cool with a drum flaker, etc., coarsely pulverize with a pulverizer such as a hammer mill, and further finely pulverize with a pulverizer such as a jet mill, followed by classification using an air classifier, etc. Thus, pulverized toner particles are obtained.
When the pulverized toner particles are used, for example, the toner particles are dispersed in a carrier liquid by a method described later, and then the radically polymerizable compound is added to the carrier liquid and stirred to cause the toner particles to absorb the radically polymerizable compound. Also good.

Further, for example, a binder resin, a radical polymerizable compound, and if necessary, other additives such as a colorant, a release agent, and a polymerization initiator are dissolved in a solvent such as ethyl acetate, and calcium carbonate is dissolved. After emulsifying / suspending in water to which a dispersion stabilizer has been added, removing the solvent, the particles obtained by removing the dispersion stabilizer are filtered and dried to obtain emulsion-dried toner particles in the liquid.
When using the above-mentioned emulsion-dried toner particles in the liquid, the toner particles may contain a radical polymerizable compound in the toner particle production process as described above, and the toner particles are dispersed in the carrier liquid in the same manner as the pulverized toner particles. Then, the radical polymerizable compound may be absorbed.
When using the above emulsion-dried toner particles in the liquid, the polymerization initiator may be included in the toner particle production process as described above, or may be included in the carrier liquid without being included in the toner particles. You may add later in an image formation process, without making it contain in a liquid developer.

  In addition, for example, a polymerizable monomer that forms a binder resin, if necessary, a colorant, a polymerization initiator (for example, benzoyl peroxide, lauroyl peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2, By adding a composition containing 4-dichloroylbenzoyl peroxide, methyl ethyl ketone peroxide, etc.) and other additives to the aqueous phase under stirring, granulating it, and then filtering and drying the particles after the polymerization reaction Polymerized toner particles are obtained.

The blending ratio of each material (thermoplastic elastomer and thermoplastic resin, if necessary, colorant, other additives, etc.) for obtaining the toner is set in consideration of required characteristics, color, etc. .
The toner particles obtained by the above method are, for example, finely pulverized in a carrier oil using a known pulverizer such as a ball mill, a bead mill, a high-pressure wet atomizer, and the like. Particles are obtained.

-Toner particle characteristics-
Examples of the volume average particle diameter D50v of the toner particles include a range of 0.5 μm to 5.0 μm, and may be 0.8 μm to 4.0 μm, and may be 1.0 μm to 3.0 μm. May be.

  The volume average particle diameter D50v of the toner particles is measured with a Coulter Multisizer (manufactured by Coulter) for toner particles of 2 μm or more. For toner particles smaller than 2 μm, a dynamic light scattering type particle size distribution measuring device (for example, LB-500 (manufactured by Horiba, Ltd.), Microtrac UPA (manufactured by Nikkiso Co., Ltd.), etc.) or laser diffraction / scattering type It is measured using a particle size distribution measuring device (for example, LS13 320 (manufactured by BECKMAN COULTER) or the like). With respect to the particle size range (channel) divided on the basis of the particle size distribution obtained by the above measurement, a cumulative distribution is drawn from the small diameter side with respect to the volume, and the particle diameter at which 50% is accumulated is defined as volume D50v.

  The toner particle content is, for example, in the range of 0.5% by mass to 40% by mass with respect to the entire liquid developer, and may be 1% by mass to 30% by mass.

<Carrier liquid>
The carrier liquid is a liquid that disperses the toner particles, and is not particularly limited. For example, a non-aqueous solvent having a volume low efficiency of 1.0 × 10 ¹⁰ Ω · cm or more can be used, and among these, the binder resin is particularly soluble. Non-aqueous solvents that are difficult to resist (that is, the toner particles are present as a solid in the liquid developer) are included.
The non-aqueous solvent refers to a solvent containing a solvent other than water, and may be a mixture of water and a solvent other than water, but may be a solvent that does not actively contain water.
Non-aqueous solvents include, for example, aliphatic hydrocarbon solvents such as paraffin oil (commercially available products are Moresco White MT-30P, Moresco White P40, Moresco White P70, Made by Matsumura Sekiyu, and Isopar L from Exxon Chemical Co., Ltd.) , Isopar M, etc.), hydrocarbon solvents such as naphthenic oil (commercially available products are Exol D80, Exol D110, Exol D130 manufactured by Exxon Chemical Co., Ltd., Naphthezol L, Naphthezol M, Naphthezol H, New Naphtezol 160 manufactured by Nippon Petrochemical Co., Ltd. , New Naphthezol 200, New Naphthezol 220, New Naphthezol MS-20P, etc.), and an aromatic compound such as toluene may be contained therein.
The non-aqueous solvent may be used alone or in combination of two or more of the above components. When the non-aqueous solvent is used as a mixture of two or more, for example, a paraffin type Examples include a mixed system of a solvent and vegetable oil, and a mixed system of a silicone solvent and vegetable oil.

-Characteristics of carrier liquid-
Examples of the volume resistivity of the carrier liquid include a range of 1.0 × 10 ¹⁰ Ω · cm to 1.0 × 10 ¹⁴ Ω · cm, and 1.0 × 10 ¹⁰ Ω · cm to 1.0 × It may be in a range of 10 ¹³ Ω · cm or less.

  The liquid developer may further contain other components as necessary. Examples of other components include polymerization initiators, curable materials, dispersants, emulsifiers, surfactants, antioxidants, wetting agents, thickeners, foaming agents, antifoaming agents, coagulants, and gelling agents. , Anti-settling agents, antistatic agents, anti-aging agents, softeners, plasticizers, fillers, flavoring agents, anti-tacking agents, release agents and the like.

<Polymerization initiator>
The polymerization initiator is an additive for initiating a polymerization reaction of the radical polymerizable compound, and generates a radical by stimulation to react with a polymerizable group in the radical polymerizable compound.
The polymerization initiator may be contained in the liquid developer, or may not be contained in the liquid developer, and the polymerization initiator may be added later in the image forming process. However, as described above, if a polymerization initiator is contained in the liquid developer, the image forming process is simplified because the image preservability is excellent even if the step of adding the polymerization initiator later is omitted.
Further, when the polymerization initiator is contained in the liquid developer, it may be contained in the toner particles or may be contained in the carrier liquid without being contained in the toner particles. However, for example, in the case of using a polymerization initiator that lowers the volume resistivity of the carrier liquid, the volume resistivity of the carrier liquid can be increased by including a polymerization initiator in the toner particles and not including the polymerization initiator in the carrier liquid. It is thought to be kept high.

A polymerization initiator is selected according to the kind of irritation | stimulations, such as a radically polymerizable compound to be used and a radiation to be used. Specifically, for example, when ultraviolet rays are used as radiation, a photopolymerization initiator is used as the polymerization initiator.
Specific examples of the polymerization initiator include, for example, acetophenone derivatives, benzophenone derivatives, benzyl derivatives, benzoin derivatives, benzoin ether derivatives, benzyl dialkyl ketal derivatives, thioxanthone derivatives, acylphosphine oxide derivatives, metal complexes, p-dialkylaminobenzoic acids. , An azo compound, a peroxide compound, and the like. These may be used alone or in combination of two or more, and may be used in combination with a sensitizer.

  Although the usage-amount of a polymerization initiator is not restrict | limited in particular, For example with respect to 100 mass parts of radically polymerizable compounds, 0.05 mass part or more and 20 mass parts or less are mentioned, for example, 0.1 mass part or more and 10 mass parts Or may be in the range of 1 to 5 parts by mass.

<Sensitizer>
Moreover, you may use a sensitizer with a polymerization initiator. The sensitizer is not activated by light irradiation alone, but when used together with the photopolymerization initiator, it is more effective than the photopolymerization initiator used alone, and amines are generally used. The sensitizer may also be included in the toner particles, may be included in the carrier liquid, or may be added before the curing step after image formation without being included in the liquid developer.

  Sensitizers include amine compounds (aliphatic amines, amines containing aromatic groups, piperidine, reaction products of epoxy resins and amines, triethanolamine triacrylate, etc.), urea compounds (allylthiourea, o-tolylthiourea, etc.) ), Sulfur compounds (sodium diethyldithiophosphate, soluble salts of aromatic sulfinic acid, etc.), nitrile compounds (N, N-diethyl-p-aminobenzonitrile, etc.), phosphorus compounds (tri-n-butylphosphine, sodium diethyl) Dithiophosphide, etc.), nitrogen compounds (Michler ketone, N-nitrisohydroxylamine derivative, oxazolidine compound, tetrahydro-1,3-oxazine compound, formaldehyde or a condensate of acetaldehyde and diamine, etc.).

The amount of the sensitizer used may be, for example, from 0 to 10 parts by mass with respect to 100 parts by mass of the polymerization initiator, and may be in the range of 0.05 to 10 parts by mass. It may be 1 part by mass or more and 5 parts by mass or less.
The selection and combination of the polymerization initiator and the sensitizer, and the blending ratio may be selected according to the radical polymerizable compound used and the image forming apparatus.

<Method for producing liquid developer>
In the liquid developer, the toner particles, the carrier liquid, and other components as necessary are mixed using a dispersing machine such as a ball mill, a sand mill, an attritor, a roll mill, etc. It is obtained by dispersing in a liquid.
The dispersion of the toner particles in the carrier liquid is not limited to the disperser, and may be dispersed by rotating a special stirring blade like a mixer, or by the shearing force of a rotor / stator known as a homogenizer. Alternatively, it may be dispersed by ultrasonic waves.
Thereafter, the obtained dispersion liquid may be filtered using, for example, a membrane filter having a pore diameter of 100 μm to remove dust and coarse particles.

[Developer cartridge]
The developer cartridge according to the present embodiment is a developer cartridge in which the liquid developer according to the present embodiment is accommodated. For example, the liquid developer stored in the developer cartridge is supplied to the image forming apparatus through a supply pipe or the like. To the developing device. Since the developer cartridge is replaced when the remaining amount of the liquid developer in the developer cartridge runs out, the developer cartridge may be attached to and detached from the image forming apparatus.

[Image Forming Method and Image Forming Apparatus]
In the image forming method of the present embodiment, a latent image forming step for forming a latent image on the surface of the latent image holding member and the latent image formed on the surface of the latent image holding member are held on the surface of the developer holding member. In addition, the development process for forming the toner image by developing with the liquid developer of the present embodiment, the transfer process for transferring the toner image formed on the surface of the latent image holding member onto the recording medium, and the transfer onto the recording medium. An image forming method comprising: a fixing step of fixing the toner image on a recording medium to form a fixed image; and a stimulus applying step of applying a stimulus to the fixed image.

  The image forming method of the present embodiment may have a polymerization initiator addition step of adding a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied, if necessary. By using an image forming method having a polymerization initiator addition step, it is considered that an image having good storage stability can be obtained even when a liquid developer not containing a polymerization initiator is used. Since the liquid developer containing no polymerization initiator has good stability, for example, the polymerization reaction of the radical polymerizable compound proceeds before the use of the liquid developer, thereby reducing the plasticizing effect of the radical polymerizable compound. This is considered to be suppressed.

The image forming apparatus of this embodiment includes a latent image holding member, a latent image forming unit that forms a latent image on the surface of the latent image holding member, and a developer holding member, and is formed on the surface of the latent image holding member. The latent image is developed with the liquid developer of the present embodiment held on the surface of the developer holding member to form a toner image and a toner image formed on the surface of the latent image holding member. Image formation comprising: transfer means for transferring onto a recording medium; fixing means for fixing a toner image transferred to the recording medium to the recording medium to form a fixed image; and stimulus applying means for giving a stimulus to the fixed image Device.
The image forming apparatus according to the present exemplary embodiment may include a polymerization initiator addition unit that adds a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied, if necessary. By using an image forming apparatus having a polymerization initiator addition means, it is considered that an image having good storage stability can be obtained even when a liquid developer not containing a polymerization initiator is used.

  The stimulus applying step only needs to apply a stimulus to the fixed image. The number of times of applying the stimulus in the image forming step may be one time or two times or more, and the fixing step and the stimulus applying step are performed simultaneously. May be.

The stimulus applying means may be provided with stimulus applying means corresponding to the stimulus applying step. In addition, when the stimulus applying process is performed twice or more, two or more stimulus applying means corresponding to each stimulus applying process may be provided, and one stimulus applying means corresponds to two or more stimulus applying processes. May be. The fixing unit may also serve as the stimulus applying unit.
When ultraviolet light or visible light is used as the stimulus, the stimulus applying means (that is, the light source that irradiates ultraviolet light or visible light) is, for example, a low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a carbon arc lamp, a xenon lamp, a chemical lamp, LED ( Light emitting diode).
Hereinafter, an image forming method and an image forming apparatus using a liquid developer in the present embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present exemplary embodiment. 1 includes a polymerization initiator addition device (polymerization initiator addition means) for adding a polymerization initiator to a toner image transferred to an intermediate transfer member, and irradiates a fixed image fixed on a recording medium with ultraviolet rays. An image forming apparatus provided with an ultraviolet irradiation device (stimulus imparting means).

The image forming apparatus 100 includes, for example, a photosensitive member 10 (latent image holding member), a charging device 20, an exposure device 12 (the charging device 20 and the exposure device 12 constitute an electrostatic latent image forming unit), and a developing device 14 (developing). Means), intermediate transfer member 16, cleaner 18, transfer fixing roller 28 (the intermediate transfer member 16 and transfer fixing roller 28 constitute transfer means, and the transfer fixing roller 28 also serves as fixing means), and a polymerization initiator addition device 32. , And an ultraviolet irradiation device 34 (radiation irradiation means). The photosensitive member 10 has a cylindrical shape, and a charging device 20, an exposure device 12, a developing device 14, an intermediate transfer member 16, and a cleaner 18 are sequentially provided on the outer periphery of the photosensitive member 10.
The operation of the image forming apparatus 100 will be briefly described below.

The charging device 20 charges the surface of the photoconductor 10 to a predetermined potential, and based on the image signal, the exposure device 12 exposes the charged surface with, for example, a laser beam to form an electrostatic latent image.
The developing device 14 includes a developing roller 14a (developer holder) and a developer storage container 14b. The developing roller 14a is provided so that a part thereof is immersed in the liquid developer 24 stored in the developer storage container 14b. The developer storage container 14b may be configured such that the liquid developer 24 is supplied from a liquid developer cartridge (not shown). The liquid developer cartridge may be configured to be attached to and detached from the image forming apparatus so that the liquid developer cartridge can be replaced when the remaining amount of the liquid developer 24 runs out.

  In the liquid developer 24, the toner particles are dispersed. For example, the liquid developer 24 is further stirred by a stirring member provided in the developer storage container 14b, so that the toner particles in the liquid developer 24 are maintained. Variations in the position of the concentration of may be reduced. Thus, the liquid developer 24 with reduced toner particle density variation is supplied to the developing roller 14a rotating in the direction of arrow A in the figure.

  The liquid developer 24 supplied to the developing roller 14a is transported to the photoconductor 10 in a state where the supply amount is limited by the regulating member, and electrostatically develops at a position where the developing roller 14a and the photoconductor 10 come close (or contact). Supplied to the latent image. As a result, the electrostatic latent image is visualized and becomes a toner image 26.

  The developed toner image 26 is conveyed to the photosensitive member 10 that rotates in the direction of arrow B in the figure and transferred to the paper (recording medium) 30. In this embodiment, the photosensitive member 10 is transferred before being transferred to the paper 30. The toner image is temporarily transferred to the intermediate transfer member 16 in order to improve the transfer efficiency to the recording medium including the separation efficiency of the toner image from the toner and to perform fixing simultaneously with the transfer to the recording medium. At this time, a peripheral speed difference may be provided between the photosensitive member 10 and the intermediate transfer member 16.

A polymerization initiator is added to the toner image transferred to the intermediate transfer body 16 by a polymerization initiator addition device 32.
As a method for adding a polymerization initiator to a toner image, for example, a method in which a solution in which a polymerization initiator is dissolved in a solvent that does not dissolve the toner image is added to the toner image by, for example, coating or spraying, or a liquid or solid Examples thereof include a method of adding a polymerization initiator (for example, a powdered solid) as it is to a toner image by, for example, spraying, but the method is not limited thereto.
Examples of the solvent that does not dissolve the toner image include a mixed solvent of hexane and IPA (isopropyl alcohol) (for example, a hexane / IPA mixing ratio in the range of 10/1 to 5/1).
In this embodiment, a polymerization initiator is added to the toner image transferred to the intermediate transfer body 16, but after the toner image is formed by the developing device 14 and before the ultraviolet ray is irradiated by the ultraviolet irradiation device 34. The polymerization initiator may be added during the time period, the polymerization initiator may be added to the toner image on the photoreceptor 10, or the polymerization initiator may be added to the fixed image 29 fixed on the recording medium. Good.

Next, the toner image conveyed in the direction of the arrow C by the intermediate transfer member 16 is transferred and fixed to the paper 30 at the contact position with the transfer fixing roller 28.
The transfer fixing roller 28 sandwiches the paper 30 together with the intermediate transfer member 16, and causes the toner image on the intermediate transfer member 16 to be in close contact with the paper 30. As a result, the toner image is transferred to the paper 30, and the toner image is fixed on the paper to form a fixed image 29. The fixing of the toner image may be performed by applying pressure and heating by providing a heat generating body on the transfer fixing roller 28. Examples of the fixing temperature include 100 ° C. or higher and 180 ° C. or lower.

If the intermediate transfer member 16 has a roller shape as shown in FIG. 1, it constitutes a roller pair with the transfer fixing roller 28. Therefore, the intermediate transfer member 16 and the transfer fixing roller 28 respectively conform to the fixing roller and the pressure roller in the fixing device. It shows a fixing function. That is, when the sheet 30 passes through the contact portion between the transfer fixing roller 28 and the intermediate transfer member 16, for example, a toner image is transferred and is heated and pressed against the intermediate transfer member 16 by the transfer fixing roller 28. Thereby, for example, the binder resin in the toner particles constituting the toner image is softened, and the toner image is infiltrated into the fibers of the paper 30 to form a fixed image 29 on the paper 30.
In this embodiment, fixing is performed simultaneously with the transfer to the paper 30. However, the transfer process and the fixing process may be performed separately, and the fixing may be performed after the transfer.

Thereafter, the ultraviolet irradiation device 34 irradiates the fixed image 29 fixed on the paper 30 with ultraviolet rays. Thereby, for example, the polymerization initiator contained in the fixed image 29 starts the curing reaction of the radiation curable material contained in the fixed image 29, and the fixed image 29 is cured.
The irradiation energy of the ultraviolet rays applied to the fixed image 29 may be within a range where the fixed image 29 is cured, and examples thereof include 10 mJ / cm ² or more and 1 J / cm ² or less. Examples of the ultraviolet irradiation time include 0.1 seconds to 60 seconds.

  On the other hand, in the photoconductor 10 in which the toner image 26 is transferred to the intermediate transfer body 16, the toner particles that are not transferred and remain on the photoconductor 10 are conveyed to a contact position with the cleaner 18 and are collected by the cleaner 18. If the transfer efficiency is close to 100% and residual toner does not cause a problem, the cleaner 18 need not be provided.

The image forming apparatus may further include a neutralization device (not shown) that neutralizes the surface of the photoreceptor 10 after the transfer and before the next charging.
For example, all of the charging device 20, the exposure device 12, the developing device 14, the intermediate transfer member 16, the transfer fixing roller 28, and the cleaner 18 included in the image forming apparatus 100 are synchronized with the rotational speed of the photosensitive member 10. It may be operated.

Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention. In the text, “parts” and “%” represent “parts by mass” and “mass%”, respectively, unless otherwise specified. Example 9 corresponds to a reference example.

[Example 1]
<Adjustment of liquid developer A1>
To 60 parts of thermoplastic resin 1 (styrene-butyl acrylate resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FSR-053, weight average molecular weight: 380,000), cyan pigment C.I. I. 40 parts of Pigment Blue 15: 3 (manufactured by Clariant Co., Ltd.) was added and kneaded with a pressure kneader. The kneaded product was coarsely pulverized to prepare a cyan pigment master batch.

Next, a mixture having the following composition was kneaded again with a pressure kneader to obtain a mixture 1.
-Cyan pigment master batch: 25 parts-Thermoplastic resin 2 (styrene-butyl acrylate resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FSR-051, weight average molecular weight: 320,000, acid value: 10): 55 Parts / thermoplastic elastomer resin 1 (manufactured by Asahi Kasei Corporation, trade name: SOE-SSL611X, hydrogenated product of styrene-butadiene-styrene block copolymer): 20 parts

The obtained mixture was pulverized with a jet mill to obtain cyan particles having a volume average particle diameter of 10 μm.
In 35 parts of the obtained cyan particles, 103 parts of a non-volatile paraffin oil which is a non-aqueous solvent (manufactured by Matsumura Oil Co., Ltd., trade name: Moresco White P40) and a dispersant (manufactured by Lubrizol Corporation, trade name) : 1.5 parts of Solsperse 17000) and finely pulverized with a ball mill, 210 parts of the paraffin oil and a liquid radical polymerizable compound (manufactured by Toagosei Co., Ltd., trade name: Aronix M211B) , 45 parts of a 40% by weight methanol solution of polymerizable group: 2) were added, and dispersion was carried out for 10 minutes using an ultrasonic washer (manufactured by ASONE Co., Ltd., model number: US-3R). Thereafter, methanol was removed under reduced pressure to obtain a liquid developer A1 containing toner particles having a volume average particle diameter of 1.1 μm.

In addition, the liquid mixture which mixed 50 mass parts of carrier liquids (namely, mixture of the said paraffin oil and a dispersing agent) and 1 mass part of radically polymerizable compounds which were used for adjustment of liquid developer A1 by the said method at 25 degreeC. In the above, it was confirmed that there was a radical polymerizable compound that did not dissolve in the carrier liquid, and it was confirmed that the radical polymerizable compound was hardly soluble in the carrier liquid.
Further, the toner particles were extracted from the obtained liquid developer A1 by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer A1 was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
A carrier liquid (paraffin oil, manufactured by Matsumura Oil Co., Ltd., trade name: Moresco White P40) is added to the obtained liquid developer, so that the toner particle content with respect to the entire liquid developer is 2.5% by mass. It diluted so that it might become, and it put into the disposable (polystyrene property).
Two transparent electrodes facing each other with a 1 mm gap were immersed in the disposable cell, and a voltage of 300 V was applied for 30 seconds. The electrode was pulled up, and the toner deposited on the plus electrode was transferred to an OHP sheet (manufactured by Fuji Xerox Co., Ltd., model number: V-516). The amount of deposited toner was measured and found to be 3.6 g / m ² . The obtained transfer image was fixed by an external fixing device under the conditions of roller temperature: 100 ° C., contact part length: 6 mm, fixing speed: 126 mm / sec, and a fixed image was obtained.

Next, Irgacure 184 (Ciba Specialty Chemicals Co., Ltd.) 0.3 parts, Irgacure 819 (Ciba Specialty Chemicals Co., Ltd.) 0.4 parts, Triethanolamine 0.5 parts, Hexane 56.3 parts And 22.5 parts of isopropanol were mixed to prepare an initiator solution.
On the surface of the fixed image, 100 μL of the initiator solution was supplied per 10 cm ² of the image and dried.
Thereafter, the surface of the dried fixed image was exposed at 1.9 J / cm ² with a metal halide lamp to obtain an evaluation image A1.

[Example 2]
<Adjustment of liquid developer A2>
To 60 parts of thermoplastic resin 1 (styrene-butyl acrylate resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FSR-053, weight average molecular weight: 380,000), cyan pigment C.I. I. 40 parts of Pigment Blue 15: 3 (manufactured by Clariant Co., Ltd.) was added and kneaded with a pressure kneader. The kneaded product was coarsely pulverized to prepare a cyan pigment master batch.

Next, a mixture having the following composition was dissolved and decomposed in a ball mill for 24 hours to obtain a mixed solution.
-Cyan pigment master batch: 25 parts-Thermoplastic resin 2 (styrene-butyl acrylate resin, manufactured by Fujikura Kasei Co., Ltd., trade name: FSR-051, weight average molecular weight: 320,000, acid value: 10): 60 Part / thermoplastic elastomer resin 2 (Asahi Kasei Co., Ltd., trade name: Asaprene T439, styrene-butadiene-styrene block copolymer): 10 parts / thermoplastic elastomer resin 3 (Asahi Kasei Co., Ltd., trade name: Toughprene) A, styrene-butadiene-styrene block copolymer): 5 parts, ethyl acetate: 200 parts

  In the obtained mixed solution, 30 parts of a liquid radical polymerizable compound (manufactured by Toagosei Co., Ltd., trade name: Aronix M211B, number of polymerizable groups: 2), 3 parts of Irgacure 184, and 6 parts of Irgacure 819 And further dissolved and dispersed for 1 hour to obtain a mixture.

On the other hand, 20 parts of calcium carbonate (manufactured by Maruo Calcium Co., Ltd., Luminous) is added as a dispersion stabilizer to an aqueous solution in which 20 parts of sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved in 135 parts of ion-exchanged water. And dispersed for 24 hours to obtain a dispersion medium.
100 parts of the mixture was added to 170 parts of this dispersion medium, and emulsified at 8000 rpm for 1 minute in an emulsifying apparatus (manufactured by SMT Co., Ltd., IKA, HIGH-FLEX HOMOGENIZER Ultra Tarrax T-25) and then emulsified at 24000 rpm for 1 minute. To obtain a suspension.

  The above suspension was placed in a separable flask equipped with a stirrer, a thermometer, and a condenser, and stirred at 40 ° C. under reduced pressure for 1 hour to remove ethyl acetate, thereby obtaining a reaction solution. After cooling, 150 parts of 10% aqueous hydrochloric acid was added to the reaction solution to decompose calcium carbonate, and solid-liquid separation was performed by centrifugation. The obtained particles were washed with 1 L of ion exchange water three times, and then vacuum dried at 30 ° C. to obtain cyan particles.

  A mixture of 14 parts of dried cyan particles, 82 parts of volatile paraffin oil (product name: Isopar L, manufactured by Exxon), 3 parts of triethanolamine, and 0.5 part of Solsperse was mixed with a ball mill. By finely pulverizing, a liquid developer A2 containing toner particles having an average particle diameter of 1.1 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A2 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A2.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
Evaluation image A2 was obtained in the same manner as evaluation image A1, except that liquid developer A2 was used instead of liquid developer A1 and the initiator solution was not supplied to the obtained fixed image.

[Example 3]
<Adjustment of liquid developer A3>
As liquid developer A1, except that Aronix M215 (manufactured by Toagosei Co., Ltd., trade name: Aronix M215, number of polymerizable groups: 2) was used instead of Aronix M211B, A liquid developer A3 containing toner particles having an average particle diameter of 1.1 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A3 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A3.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A3 was obtained in the same manner as the evaluation image A1, except that the liquid developer A3 was used instead of the liquid developer A1.

[Example 4]
<Adjustment of liquid developer A4>
As a liquid radical polymerizable compound, Aronix M1600 (manufactured by Toagosei Co., Ltd., trade name: Aronix M1600, number of polymerizable groups: 2) was used instead of Aronix M211B, in the same manner as in liquid developer A1, A liquid developer A4 containing toner particles having an average particle diameter of 1.2 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A4 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A4.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A4 was obtained in the same manner as the evaluation image A1, except that the liquid developer A4 was used instead of the liquid developer A1.

[Example 5]
<Adjustment of liquid developer A5>
The same as liquid developer A1 except that DPHA (manufactured by Daicel Cytec Co., Ltd., compound name: dipentaerythritol hexaacrylate, polymerizable group number: 6) was used as the liquid radical polymerizable compound instead of Aronix M211B. Thus, a liquid developer A5 containing toner particles having an average particle diameter of 1.2 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A5 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A5.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A5 was obtained in the same manner as the evaluation image A1, except that the liquid developer A5 was used instead of the liquid developer A1.

[Example 6]
<Adjustment of liquid developer A6>
As a liquid radical polymerizable compound, pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: A-TMMT, number of polymerizable groups: 3, hereinafter abbreviated as PETA) is used in place of Aronix M211B. In the same manner as Liquid Developer A1, Liquid Developer A6 containing toner particles having an average particle diameter of 1.2 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A6 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A6.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A6 was obtained in the same manner as the evaluation image A1, except that the liquid developer A6 was used instead of the liquid developer A1.

[Example 7]
<Adjustment of liquid developer A7>
Liquid developer A2 except that 2-phenoxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd., number of polymerizable groups: 1, hereinafter abbreviated as PEA) was used as the liquid radical polymerizable compound instead of Aronix M211B. Similarly, a liquid developer A7 containing toner particles having an average particle diameter of 1.1 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A7 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A7.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A7 was obtained in the same manner as the evaluation image A2, except that the liquid developer A7 was used instead of the liquid developer A2.

[Example 8]
<Production of evaluation image>
An evaluation image A8 was obtained in the same manner as the evaluation image A1 except that OK top coat paper (manufactured by Oji Paper Co., Ltd., 128 g / m ² ) was used instead of the OHP sheet.

[ Reference Example 9] <Adjustment of Liquid Developer A9>
A liquid developer A9 containing toner particles having an average particle diameter of 1.2 μm was prepared in the same manner as the liquid developer A1 except that the amount of the thermoplastic resin 2 was changed to 75 parts and the thermoplastic elastomer resin 1 was not used. Obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A9 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A9.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A9 was obtained in the same manner as the evaluation image A1, except that the liquid developer A9 was used instead of the liquid developer A1.

[Example 10]
<Adjustment of liquid developer A10>
Except for changing the thermoplastic resin 2 to a polyester resin (manufactured by Kao Corporation, weight average molecular weight: 14000, acid value: 10), toner particles having an average particle diameter of 1.2 μm were obtained in the same manner as the liquid developer A1. A liquid developer A10 containing was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A10 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A10.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A10 was obtained in the same manner as the evaluation image A1, except that the liquid developer A10 was used instead of the liquid developer A1.

[Example 11]
<Adjustment of liquid developer A11>
A liquid developer A11 containing toner particles having an average particle diameter of 1.2 μm was obtained in the same manner as the liquid developer A1, except that 45 parts of the methanol solution of the liquid radical polymerizable compound was changed to 23 parts.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A11 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A11.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A11 was obtained in the same manner as the evaluation image A1, except that the liquid developer A11 was used instead of the liquid developer A1.

[Example 12]
<Adjustment of liquid developer A12>
A liquid developer A12 containing toner particles having an average particle diameter of 1.2 μm was obtained in the same manner as the liquid developer A1 except that 45 parts of the methanol solution of the liquid radical polymerizable compound was changed to 12 parts.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer A12 is hardly soluble in the said carrier liquid used for adjustment of liquid developer A12.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image A12 was obtained in the same manner as the evaluation image A1, except that the liquid developer A12 was used instead of the liquid developer A1.

[Comparative Example 1]
<Adjustment of liquid developer B1>
The average particle size is the same as that of the liquid developer A1, except that the amount of paraffin oil added after pulverization is changed from 210 parts to 228 parts and 45 parts of a methanol solution of a liquid radical polymerizable compound is not used. A liquid developer B1 containing 1.0 μm toner particles was obtained.

<Production of evaluation image>
An evaluation image B1 was obtained in the same manner as the evaluation image A1, except that the liquid developer B1 was used instead of the liquid developer A1.

[Comparative Example 2]
<Adjustment of liquid developer B2>
Instead of 45 parts of the methanol solution of the liquid radically polymerizable compound, 18 parts of the liquid radically polymerizable compound Aronix M220 (manufactured by Toagosei Co., Ltd., trade name: Aronix M220, number of polymerizable groups: 2) is used under reduced pressure. A liquid developer B2 containing toner particles having an average particle size of 1.0 μm was obtained in the same manner as the liquid developer A1 except that the step of removing methanol was not performed.

In addition, in the mixed liquid obtained by mixing 50 parts by mass of the carrier liquid used for the adjustment of the liquid developer B2 and 1 part by mass of the radical polymerizable compound at 25 ° C., the radical polymerizable compound that does not dissolve in the carrier liquid is obtained. It was confirmed that it did not exist, and it was confirmed that the radical polymerizable compound was easily soluble (not hardly soluble) in the carrier liquid.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image B2 was obtained in the same manner as the evaluation image A1, except that the liquid developer B2 was used instead of the liquid developer A1.

[Comparative Example 3]
<Adjustment of liquid developer B3>
An average particle size of 1.2 μm was obtained in the same manner as the liquid developer A1, except that the 40% by mass methanol solution of the radical polymerizable compound was changed to a 4% by mass methanol solution of tricresyl phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.). A liquid developer B3 containing the toner particles was obtained.

<Production of evaluation image>
An evaluation image B3 was obtained in the same manner as the evaluation image A1, except that the liquid developer B3 was used instead of the liquid developer A1.

[Comparative Example 4]
<Adjustment of liquid developer B4>
As a liquid radical polymerizable compound, except that Aronix M220 (manufactured by Toagosei Co., Ltd., trade name: Aronix M220, polymerizable group number: 2) was used instead of Aronix M211B, the same as liquid developer A2, A liquid developer B4 containing toner particles having an average particle diameter of 1.2 μm was obtained.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer B4 is easily soluble (it is not hardly soluble) in the said carrier liquid used for adjustment of liquid developer B4. .
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image B4 was obtained in the same manner as the evaluation image A2, except that the liquid developer B4 was used instead of the liquid developer A2.

[Comparative Example 5]
<Adjustment of liquid developer B5>
Instead of a liquid radical polymerizable compound, a radical polymerizable compound N ′, N′-methylenebisacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd., number of polymerizable groups: 2, hereinafter abbreviated as MBA) that is solid at 25 ° C. A liquid developer B5 containing toner particles having an average particle diameter of 1.3 μm was obtained in the same manner as in the liquid developer A2 except that it was used.

In addition, by the said method, it was confirmed that the said radically polymerizable compound used for adjustment of liquid developer B5 is hardly soluble in the said carrier liquid used for adjustment of liquid developer B5.
Further, the toner particles were extracted from the obtained liquid developer by the above method and subjected to NMR measurement. As a result, it was confirmed that the radical polymerizable compound was contained in the toner particles.
Further, the content of the radical polymerizable compound contained in the toner particles in the obtained liquid developer was measured by the above method. The results are shown in Table 1.

<Production of evaluation image>
An evaluation image B5 was obtained in the same manner as the evaluation image A2, except that the liquid developer B5 was used instead of the liquid developer A2.

[Evaluation]
<Evaluation of fixing temperature>
In the production of the evaluation image, in the step of fixing the obtained transfer image to obtain a fixed image, the roller temperature of the external fixing device is increased from 70 ° C. to 130 ° C. every 20 ° C., and fixing is performed at each temperature. It was visually confirmed whether or not the transparency of the image was increased by fixing.
Of the fixing temperatures at which the transparency of the image is increased by fixing, A is the lowest fixing temperature of less than 70 ° C., B is the case of 70 ° C. or more and less than 90 ° C., and C is the case of 90 ° C. or more and less than 110 ° C. The case of ℃ or higher was evaluated as D. The evaluation results are shown in Table 1.

<Evaluation of image preservation>
The obtained evaluation image was vacuum-dried at 40 ° C. for 1 hour to volatilize the carrier liquid, and then the image surfaces of the two evaluation images were superposed on each other in an environment with a temperature of 50 ° C. and a humidity of 85%. The sample was allowed to stand for 3 days with a load of 500 g / cm ² applied thereto. The superimposed images were peeled off, and the presence or absence of fusing of the images between the recording sheets and the transfer to the non-image area was visually observed. A level where there is no problem in image storability, B is a level where some change is observed in the image but there is no practical problem, and C is a level where fusing or transfer is observed in the image and is not acceptable in practice. evaluated. The evaluation results are shown in Table 1.

  As can be seen from the results in Table 1, it can be seen that in the example, the minimum fixing temperature is kept low and the storage stability of the obtained image is improved as compared with the comparative example.

10 Photoconductor (latent image carrier)
12 Exposure device 14 Developing device (Developing means)
14a Development roller (developer holder)
16 Intermediate transfer body 18 Cleaner 20 Charging device (charging means)
24 Liquid developer 26 Toner image 28 Transfer fixing roller (transfer means, fixing means)
29 Fixed image 30 Paper (recording medium)
32 Polymerization initiator addition device 34 UV irradiation device (stimulus imparting means)
100 Image forming apparatus

Claims (8)

Carrier liquid,
Toner particles dispersed in the carrier liquid, comprising a binder resin and a radical polymerizable compound, the radical polymerizable compound being a liquid compound at 25 ° C., and 50 parts by mass of the carrier liquid; Toner particles that are poorly soluble compounds in which at least part of the radical polymerizable compound is not dissolved in the carrier liquid under a condition in which 1 part by mass of the radical polymerizable compound is mixed at 25 ° C .;
And the binder resin contains a styrene-based thermoplastic resin and a styrene-based thermoplastic elastomer resin .   The liquid developer according to claim 1, wherein the radical polymerizable compound has two or more polymerizable groups in one molecule.   The liquid developer according to claim 1, further comprising a polymerization initiator.   A developer cartridge containing the liquid developer according to any one of claims 1 to 3. A latent image forming step of forming a latent image on the surface of the latent image holding member;
4. The toner developed by the liquid developer according to claim 1, wherein the latent image formed on the surface of the latent image holding member is held on the surface of the developer holding member. 5. A development process for forming an image;
A transfer step of transferring the toner image formed on the surface of the latent image holding member onto a recording medium;
A fixing step of fixing the toner image transferred to the recording medium to the recording medium to form a fixed image;
A stimulus applying step of applying a stimulus to the fixed image;
An image forming method.   The image forming method according to claim 5, further comprising a polymerization initiator adding step of adding a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied by the stimulus applying step. A latent image carrier,
Latent image forming means for forming a latent image on the surface of the latent image holder;
The liquid developer according to any one of claims 1 to 3, wherein the liquid developer according to any one of claims 1 to 3 is contained, the developer holding body is provided, and the latent image formed on the surface of the latent image holding body is Developing means for developing with the liquid developer held on the surface of the developer holder to form a toner image;
Transfer means for transferring the toner image formed on the surface of the latent image holding member onto a recording medium;
Fixing means for fixing the toner image transferred to the recording medium to the recording medium to form a fixed image;
A stimulus applying means for applying a stimulus to the fixed image;
An image forming apparatus.   The image forming apparatus according to claim 7, further comprising a polymerization initiator adding unit that adds a polymerization initiator to at least one of the toner image and the fixed image before the stimulus is applied by the stimulus applying unit.