JP2017068246A - Curable liquid developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable liquid developer that prevents contamination of members inside the apparatus to maintain high image quality for a long period, and exhibits excellent fixability in a humid environment.SOLUTION: There is provided a curable liquid developer containing toner particles, a polymerization initiator, and a cationic polymerizable liquid monomer, wherein the cationic polymerizable liquid monomer contains a compound represented by the following formula (A): (R-CH=CH-O-)-CH, wherein m represents an integer of 12 or more and 50 or less; n represents an integer of 2 or more; R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, inclusive.SELECTED DRAWING: None

Description

  The present invention relates to a liquid developer used in an image forming apparatus using an electrophotographic method such as electrophotographic method, electrostatic recording method, and electrostatic printing.

In the electrophotographic system, the surface of an image carrier such as a photoconductor is uniformly charged (charging process), and an electrostatic latent image is formed on the surface of the image carrier by exposure (exposure process). The electrostatic latent image is developed with a developer made of colored resin particles (development process), the developer image is transferred to a recording medium such as paper or plastic film (transfer process), and the transferred developer image is recorded on the recording medium. It is a method of obtaining a printed matter by fixing (fixing step).
In this case, the developer is a liquid developer in which colored resin particles composed of a material including a colorant such as a pigment and a binder resin are used in a dry state, and liquid development in which the colored resin particles are dispersed in an electrically insulating liquid. It is roughly divided into agents.
In recent years, there is an increasing need for colorization and high-speed printing for image forming apparatuses such as copying machines, facsimiles, and printers that use electrophotography. In color printing, a high-resolution and high-quality image is required. Therefore, a developer capable of forming a high-resolution and high-quality image and corresponding to high-speed printing is required.
A liquid developer is known as an advantageous developer for color image reproducibility. In the liquid developer, since the aggregation of the colored resin particles in the liquid developer is difficult to occur during storage, fine toner particles can be used. Therefore, the liquid developer can easily obtain characteristics excellent in fine line image reproducibility and gradation reproducibility. Taking advantage of these excellent features, development of a high-quality high-speed digital printing apparatus using electrophotographic technology in which toner particles of a liquid developer are charged and the developer is developed and transferred by electrophoresis is being actively developed. Under such circumstances, development of a liquid developer having better characteristics is demanded.
Conventionally, a liquid developer in which colored resin particles are dispersed in an electrically insulating liquid such as a hydrocarbon organic solvent or silicone oil is known. However, if the electrically insulating liquid remains on a recording medium such as paper or plastic film, the image quality may be significantly deteriorated, and the electrically insulating liquid needs to be removed. For removing the electrically insulating liquid, a method of volatilizing and removing the electrically insulating liquid by applying heat energy is generally used. However, this method is not preferable from the viewpoint of environment and energy saving because there is a possibility that the organic solvent vapor may be released outside the apparatus or a large amount of energy is required.
As a countermeasure against this, a method of curing an electrically insulating liquid by photopolymerization has been proposed. As the photocurable liquid developer, a monomer having a reactive functional group is used as an electrically insulating liquid and a photopolymerization initiator is further dissolved. This photo-curable liquid developer is cured by irradiating light such as ultraviolet rays to react with a reactive functional group, and can cope with high speed. Such a photocurable liquid developer is proposed in Patent Document 1.
In Patent Document 1, an acrylate monomer such as urethane acrylate is exemplified as a monomer having a reactive functional group.
In Patent Document 2, it is proposed to use a curable liquid vehicle having a specific resistance range as the curable electrical insulating liquid. Examples of the curable liquid vehicle include cationic polymerization type curable developers such as epoxy compounds, vinyl ethers, and cyclic vinyl ethers.
Furthermore, in Patent Document 3, a vinyl ether monomer is used as a cationically polymerizable liquid monomer, and combined with a specific polymerization initiator, a decrease in volume resistance is prevented, and an ultraviolet curable liquid that achieves both high image density and fixability. Developers are illustrated.

JP 2003-57883 A Japanese Patent No. 3442406 Japanese Patent Laying-Open No. 2015-127812

However, since the acrylate monomer has a low volume resistance and tends to lower the potential of the electrostatic latent image in the development process, it is difficult to obtain a high image density and image blurring (resulting in an image with inferior sharpness) occurs. was there.
On the other hand, when the above cationic polymerizable curable liquid developer is used, the curing may be inhibited by humidity. In order to maintain the fixability of the liquid developer even in a humidity environment, at least a polyfunctional monomer having two or more vinyl ether groups in one molecule is used as a cationic polymerizable liquid monomer used in such a liquid developer. I think it is preferable.
As such a polyfunctional vinyl ether monomer, in Patent Document 2, 1,4-cyclohexanedimethanol divinyl ether, diethylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, octanediol divinyl ether, and decanediol divinyl ether are used. Illustrated.
In Patent Document 3, trimethylolpropane trivinyl ether, 2-ethyl-1,3-hexanediol divinyl ether, 2,4-diethyl-1,5-pentanediol divinyl ether, 2-butyl-2-ethyl Examples include -1,3-propanediol divinyl ether, neopentyl glycol divinyl ether, pentaerythritol tetravinyl ether, 1,2-decanediol divinyl ether, and the like.
Although the use of these polyfunctional vinyl ether monomers improved the fixability in a humidity environment, the above-mentioned conventional polyfunctional vinyl ether monomers were all low in boiling point and easily volatile. .

In an image forming apparatus using a curable liquid developer, after image formation and printing are completed, the developing roller, the intermediate transfer member, and the like in the apparatus are covered with a carrier liquid in the curable liquid developer. It will be in a standby state.
However, in the liquid developer using the conventional liquid monomer as described above, the carrier liquid is volatilized little by little. Although the diffusion to the outside of the apparatus can be prevented by providing a mechanism for adsorbing the volatilized component, the apparatus becomes large and expensive due to the installation of the adsorber.
On the other hand, it is possible to seal the device so that the volatilized carrier component is not diffused outside, but the carrier component volatilized inside the device contaminates other members. Among them, the charger is sensitive to contamination by volatile components, and when it is contaminated, the charging uniformity of the photoreceptor is lowered, and the image quality is adversely affected. Although the image quality is restored to some extent by cleaning the member, it is complicated and requires a running cost to perform the complete cleaning.
The present invention provides a liquid developer that solves the above problems. That is, the present invention has extremely low volatilization of the vinyl ether compound used in the curable liquid developer, prevents contamination of members inside the apparatus, maintains high image quality for a long time, and has excellent fixability even in a humidity environment. A curable liquid developer exhibiting the following is provided.

The present invention
A curable liquid developer containing toner particles, a polymerization initiator, and a cationic polymerizable liquid monomer,
The cationic polymerizable liquid monomer contains a compound represented by the following formula (A), and is a curable liquid developer.
(R—CH═CH—O—) _n —C _m H _{(2m + 2-n)} Formula (A)
[In the formula (A), m represents an integer of 12 or more and 50 or less, n represents an integer of 2 or more, and R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]

  According to the present invention, it is possible to provide a curable liquid developer exhibiting excellent fixability even in a humidity environment while preventing contamination of members inside the apparatus and maintaining high image quality for a long time.

Schematic configuration diagram of main parts of image forming apparatus Cross section of image forming unit ¹ H-NMR spectrum chart of Compound A-13 Enlarged view of FIG. Enlarged view of FIG. Enlarged view of FIG. FT-IR spectrum chart of Compound A-13

Hereinafter, the present invention will be described in detail.
The curable liquid developer of the present invention (hereinafter also simply referred to as a liquid developer) contains toner particles, a polymerization initiator, and a cationically polymerizable liquid monomer.
Hereinafter, each component contained in the curable liquid developer of the present invention will be described.

[Cationically polymerizable liquid monomer]
In the present invention, the cationically polymerizable liquid monomer contains a compound represented by the following formula (A).
(R—CH═CH—O—) _n —C _m H _{(2m + 2-n)} Formula (A)
[In the formula (A), m represents an integer of 12 or more and 50 or less (preferably 12 or more and 25 or less, more preferably 18 or more and 25 or less), n represents an integer of 2 or more, and R represents a hydrogen atom or carbon. An alkyl group having a number of 1 or more and 3 or less is represented. ]

In the above formula (A),
(R—CH═CH—O—) _n (hereinafter referred to as formula (A1)) represents an embodiment of a vinyl ether group, and n represents the number of vinyl ether groups contained in one molecule of the compound.
In the present invention, since n is an integer of 2 or more, a polyfunctional monomer having a plurality of vinyl ether groups is shown. By using a polyfunctional monomer, it is possible to obtain a liquid developer that is hardly affected by polymerization inhibition due to moisture and has good fixability in a humidity environment.
In general, the cationic polymerization reaction is a polymerization reaction in which an acid decomposed from a polymerization initiator by irradiation with light reacts with a monomer to produce a cationic active species. As long as this cationic active species exists, the polymerization reaction proceeds one after another. Conceivable.
In the present invention, it is considered that the acid generated from the polymerization initiator and the vinyl ether structure react to produce a cationically active species. At this time, if water molecules are present in the vicinity of the monomer, this cationically active species is trapped, and further polymerization does not proceed.
That is, the chain reaction of one vinyl ether structure is stopped per water molecule. From the above, it is advantageous for fixing the liquid developer that the number of n is large.
On the other hand, when the number of n becomes large, the corresponding cationic polymerizable liquid monomer becomes difficult to obtain.
Considering these, n in the formula (A1) is preferably 2 or more, 6 or less, more preferably 2 or more and 4 or less, and further preferably 2 or more and 3 or less.

On the other hand, in the above formula (A),
_{-C m H (2m + 2-} n) ( hereinafter, represent the formula (A2)) is an alkane chain, m is the number of carbon atoms in the alkane chain. Hydrocarbons may be branched in the middle, and by increasing the carbon number of the alkane chain to 12 or more, the volatilization of the monomer can be substantially prevented. Further, if the carbon number is 18 or more, the volatilization of the monomer is completely prevented. Can be prevented.
On the other hand, as for the upper limit of the carbon number of the alkane chain, attention should be paid to the viscosity. The viscosity of the liquid developer is preferably 0.5 mPa · s or more and 100 mPa · s or less at 25 ° C., and 0.5 mPa · s or more and 30 mPa · s or less in order to maintain the electrophoresis speed of the toner particles. It is more preferable.
When the viscosity is higher than the above range, the electrophoresis speed of the toner particles tends to decrease, and the printing speed tends to decrease or the printing density tends to decrease.
In the curable liquid developer of the present invention, the viscosity of the cationic polymerizable liquid monomer is a cationic polymerization having a low viscosity other than the compound represented by the formula (A), the main component being the compound represented by the formula (A). The viscosity can be adjusted by adding a viscosity modifier such as an ionic liquid monomer or an oligomer having a high viscosity.
For this reason, the viscosity of the compound represented by the formula (A) is preferably 0.5 mPa · s or more and 100 mPa · S or less, and more preferably 0.5 mPa · s or more and 30 mPa · S or less. This is because it is not necessary to add a viscosity modifier.
On the other hand, regarding the carbon number of the alkane chain in the formula (A2), the viscosity of the monomer itself tends to increase as the carbon number increases. Considering these, the carbon number of the alkane chain in the formula (A2) (that is, the value of m) is preferably 50 or less, and more preferably 25 or less.

  Specific examples of the compound represented by the formula (A) [Exemplary Compounds A-1 to A-31] are shown below, but the present invention is not limited to these examples.

(In the exemplified compounds, C _x H _y represents a linear hydrocarbon)

  The compounds represented by the formula (A) can be used alone or in combination of two or more. Further, the content of the compound represented by the above formula (A) in the cationic polymerizable liquid monomer is preferably 60 parts by mass or more and 100 parts by mass or less in 100 parts by mass of the cationic polymerizable liquid monomer, and 70 parts by mass. The amount is more preferably 100 parts by mass or less.

In the present invention, the cationically polymerizable liquid monomer is selected from liquids having a high volume resistivity and electrical insulation and low viscosity near room temperature.
The cationically polymerizable liquid monomer is preferably selected from liquids that do not dissolve the binder resin contained in the toner particles.
Specifically, it may be selected from a combination of a cationic polymerizable liquid monomer and a binder resin such that the binder resin to be dissolved is 1 part by mass or less with respect to 100 parts by mass of the cationic polymerizable liquid monomer at a temperature of 25 ° C. preferable.
Here, the volume resistivity of the cationic polymerizable liquid monomer is preferably about 1 × 10 ⁹ Ω · cm to about 1 × 10 ¹⁵ Ω · cm, and preferably about 1 × 10 ¹⁰ Ω · cm to 1 × 10 ¹⁵ Ω. -More preferably, it is about cm or less.
When the volume resistivity is less than 1 × 10 ⁹ Ω · cm, the potential of the electrostatic latent image tends to drop, and it tends to be difficult to obtain a high optical density or to cause image blurring.
On the other hand, the viscosity of the cationically polymerizable liquid monomer is preferably about 0.5 mPa · s to less than 100 mPa · s at 25 ° C., more preferably about 0.5 mPa · s to less than 30 mPa · s.

In the curable liquid developer of the present invention, the cationically polymerizable liquid monomer contains a compound represented by the formula (A). The compound represented by the formula (A) is a vinyl ether compound having no hetero atom other than the vinyl ether structure (—CH═CH—O—C—).
Here, the hetero atom refers to an atom other than a carbon atom and a hydrogen atom.
When a heteroatom other than the vinyl ether structure is contained in the vinyl ether compound, the electron density tends to be biased in the molecule due to the difference in electronegativity between the heteroatom and the carbon atom. Since the pair or empty electron orbit may become a path of conduction electrons or holes, the volume resistivity is likely to decrease.
The compound represented by the formula (A) does not have a carbon-carbon double bond other than the vinyl ether structure in the compound. The carbon-carbon double bond has an electron occupied orbital with a high energy level and a non-electron occupied orbital with a low energy level, but these tend to be a path for electrons and holes, and tend to lower the volume resistivity.
When a carbon-carbon double bond other than the vinyl ether structure is contained in the compound, the volume resistivity tends to be lowered by such a mechanism.

Furthermore, the compound represented by the formula (A) has a structure having no cyclo ring. When it has a cyclo ring, the solubility parameter (Solubility Parameter, hereinafter abbreviated as SP value) tends to increase. When the SP value increases, the compound itself easily absorbs moisture, and therefore, in a high humidity environment, the water molecule absorbed by the compound tends to inhibit the curing of cationic polymerization, and may cause poor fixing of the liquid developer.
Here, the SP value is one of affinity parameters. In a regular solution, that is, in a solution having no action such as electrostatic interaction, association (hydrogen bond), dipole interaction, etc., two components are present. Since the acting force is assumed to be only an intermolecular force, the solubility parameter is used as a measure of the intermolecular force. Although an actual solution is not necessarily a regular solution, it is empirically known that the smaller the difference between the SP values of the two components, the greater the solubility.
The SP value of a vinyl ether compound is usually about 7.0 to 10.0 (cal / cm ³ ) ^1/2 , but in the case of a vinyl ether compound containing a cyclo ring structure, 8.5 to 10.0 (cal
/ Cm ³ ) ^{1/2, which} is a relatively large value. On the other hand, since the SP value of water is 23.4 (cal / cm ³ ) ^1/2, which is a large value compared to other solvents, the SP value of the vinyl ether compound is made as small as possible to dissolve water. It is good to prevent.
As the SP value calculation method, Hansen and Hoy calculation methods that are estimated from the molecular structure are known, but it is preferable to use the Fedors estimation method that is relatively simple.

  In view of the above points, the cationically polymerizable liquid monomer preferably has an alkane chain structure that does not have a heteroatom or a carbon-carbon double bond and does not have a cyclo ring in addition to the vinyl ether structure.

In the present invention, from the viewpoint of the SP value, if there is a methyl group at the end of the alkane chain, the SP value tends to be low. Therefore, the one having the methyl group remaining at the end of the alkane chain is less susceptible to curing inhibition by moisture. This is advantageous in terms of fixing properties.
That is, from the viewpoint of fixability, the compound represented by the above formula (A) is such that at least one vinyl ether group represented by the following formula (A1) in the formula (A) has the following formula (A) in the formula (A): It is preferably bonded to a carbon atom other than the terminal of the carbon atom forming the alkane chain represented by A2).
(R—CH═CH—O—) _n formula (A1)
_{-C m H (2m + 2-} n) Formula (A2)
[In the formulas (A1) and (A2), m represents an integer of 12 to 50 (preferably 12 to 25, more preferably 18 to 25), n represents an integer of 2 and R, Represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]

The compound represented by the above formula (A) may be synthesized by replacing the hydrogen atom of alkane with a plurality of hydroxyl groups and then converting the hydroxyl groups into vinyl ether.
The alkane used as the raw material preferably has 25 or less carbon atoms from the viewpoint of availability.
In particular, those having 12 or 18 carbon atoms can be suitably used because they can be collected from natural products such as castor oil.
There are also commercially available hydroxylated alkanes such as 1,2-dodecanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), 1,12-dodecanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), 1,12-octadecanediol (trade name). : HSTOL Ogura Gosei Kogyo Co., Ltd.), phytantriol (manufactured by Kuraray), etc.
As a method for obtaining a vinyl ether group from a hydroxyl group, a method using acetylene gas as described in WO2013 / 018302, AM. CHEM. SOC. 9, VOL. 124, NO. 8, 2002, 1590-1591, a method using vinyl acetate and an iridium complex, a method using palladium and bathophenanthroline, and the like are known.

In the present invention, the cationic polymerizable liquid monomer can contain various cationic polymerizable liquid monomers for the purpose of a viscosity modifier and the like in addition to the compound represented by the formula (A).
The cationic polymerizable liquid monomer that can be contained is not limited as long as it does not impair the developability and fixability of the liquid developer, and is represented by an acrylic monomer, a cyclic ether monomer such as epoxide and oxetane, and the formula (A). And cationically polymerizable liquid monomers such as vinyl ether compounds other than the above compounds.
Among them, in the present invention, vinyl ether compounds other than the compound represented by the formula (A), which can obtain a curable liquid developer having a high volume resistivity, a low viscosity, and a high sensitivity are preferable.
Specific examples of the vinyl ether compound other than the compound represented by the formula (A) [Exemplary compounds B-1 to B-22] are shown below, but the present invention is not limited to these examples.

These vinyl ether compounds can be used alone or in combination of two or more.
Among these, preferable in consideration of volatility, the number of carbon atoms in the alkane chain portion such as dodecyl vinyl ether (B-1), octadecyl vinyl ether (B-2), isostearyl vinyl ether (B-3) is 12 or more. Examples thereof include monofunctional vinyl ether compounds that are 50 or less.
Since these vinyl ether compounds are all monofunctional monomers having one vinyl ether group, they are poor in fixability in a humidity environment.
However, fixability in a humidity environment can be maintained by using together with the compound represented by the above formula (A).
The content of the monofunctional vinyl ether compound is preferably 40 parts by mass or less in 100 parts by mass of the cationic polymerizable liquid monomer (that is, the compound represented by the formula (A) is 60 parts by mass or more), and more preferably. Is 30 parts by mass or less (that is, the compound represented by the formula (A) is 70 parts by mass or more).

On the other hand, preferable polyfunctional monomers in consideration of fixing properties include cyclohexanedimethanol divinyl ether (B-15), trimethylolpropane trivinyl ether (B-16), 2-ethyl-1,3-hexanediol divinyl ether. (B-17), 2,4-diethyl-1,5-pentanediol divinyl ether (B-18), 2-butyl-2-ethyl-1,3-propanediol divinyl ether (B-19), pentaerythritol Examples thereof include tetravinyl ether (B-20) and 2-decanediol divinyl ether (B-21).
Although these vinyl ether compounds are all excellent in fixability in a humidity environment, the alkane chain portion has less than 12 carbon atoms. For this reason, when the cationic polymerizable liquid monomer is composed only of these vinyl ether compounds, the members inside the apparatus are contaminated due to volatilization of the vinyl ether compounds.
However, when used in combination with the compound represented by the above formula (A), contamination of members inside the apparatus can be prevented.
The content of the polyfunctional vinyl ether compound having less than 12 carbon atoms in the alkane chain portion is preferably 40 parts by mass or less in 100 parts by mass of the cationic polymerizable liquid monomer (that is, represented by the above formula (A)). The compound is 60 parts by mass or more), more preferably 30 parts by mass or less (that is, the compound represented by the above formula (A) is 70 parts by mass or more).

In the present invention, the cationic polymerizable liquid monomer may contain an oligomer in order to increase the viscosity of the cationic polymerizable liquid monomer.
A vinyl ether oligomer having a vinyl ether group at the end of the oligomer is a preferred embodiment because it is polymerized with a cationically polymerizable liquid monomer and exhibits excellent curability.
Specific examples of the vinyl ether oligomer [Exemplary Compounds C-1 to C-6] are shown below, but the present invention is not limited to these examples.

(In the above formula, m and n are each independently an integer such that the weight average molecular weight of the exemplified compound is 1,000 or more and 10,000 or less.)

The vinyl ether oligomer can be produced by using a hydrogenated polyolefin having a hydroxyl group at a terminal as a raw material and converting the hydroxyl group to vinyl ether.
The weight average molecular weight of the vinyl ether oligomer having a vinyl ether group at the terminal is preferably 10,000 or less in consideration of compatibility with the compound represented by the above formula (A). On the other hand, in order to develop the function as a thickener, the weight average molecular weight of the vinyl ether oligomer is preferably 1,000 or more.
When expressing the function as a thickener, the content of the vinyl ether oligomer is preferably about 1 part by mass or more and 30 parts by mass or less, preferably about 5 parts by mass or more and 20 parts by mass or less in 100 parts by mass of the cationic polymerizable liquid monomer. Is more preferable.

[Polymerization initiator]
In order to initiate the polymerization reaction of the cationic polymerizable liquid monomer, a reaction called an initiation reaction is required. A substance used for this purpose is a polymerization initiator.
In the present invention, examples of the polymerization initiator include the following.
Cationic polymerization initiators include, but are not limited to, onium salt compounds; nonionic compounds such as sulfonyldiazomethane compounds, oxime sulfonate compounds, imide sulfonate compounds, and trichloromethyltriazine compounds.
Examples of onium salt compounds include iodonium compounds (for example, IRGACURE (registered trademark) 250 manufactured by BASF, WPI-113, WPI-116, WPI-169, WPI-170, WPI-124 or more, Wako Pure Chemical Industries, Ltd.), And sulfonium-based compounds (triarylsulfonium salt-based compounds CPI-110P, CPI-210S or more, manufactured by San Apro, aromatic sulfonium salt-based compounds, Adekaoptomer SP-150 ADEKA Corporation).
Examples of the nonionic compound include the following compounds.
As sulfonyldiazomethane-based compounds, WPAG-145 (Bis (cyclohexylsulfonyl) diazomethane), WPAG-170 (Bis (t-butylsulfonyl) diazomethane), WPAG-199 (Bis (f-toluene)), WPAG-199 (Bis (f-toluene)) ).
As an oxime sulfonate-based compound, IRGACURE (registered trademark) PAG103 [(5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl) acetonitryl], IRGACURE (registered trademark) PAG108 [(5-octimyloxy) 5] -2-ylidene)-(2-methylphenyl) acetontrile)], IRGACURE (registered trademark) PAG121 [(5-p-toluenesulfonyloxyimino-5H-thiophene-2-ylidene)-(2-methylphenyl) acetonitrileBA, above Made It is below.
Examples of imide sulfonate compounds include N-trifluoromethylsulfuccinimide, N-Hydroxyphthalmide triflate, N-Hydroxy-5-norbornenene-2, 3-dicarboxene-2, 3-dicarboxenebide.
As a trichloromethyltriazine compound, 2- [2- (Furan-2-yl) ethylene] -4,6-bis (trichloromethyl) -s-triazine, 2- [2- (5-Methylfuran) manufactured by Sanwa Chemical Co., Ltd. -2-yl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- (methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [2- (3,4- Dimethylphenethyl) ethyl] -4,6-bis (trichloromethyl) -s-triazine.

Of the cationic polymerization initiators, nonionic compounds such as sulfonyldiazomethane compounds, oxime sulfonate compounds, imide sulfonate compounds, and trichloromethyltriazine compounds are preferred. This is because even when the nonionic compound and the cationic polymerizable liquid monomer are mixed, the volume resistivity of the cationic polymerizable liquid monomer is hardly reduced.
About the said imide sulfonate type compound, a specific example is shown and further demonstrated.
Examples of the imide sulfonate compound include compounds represented by the following general formula (1).

[In General Formula (1), R ₁ and R ₂ are bonded to each other to form a ring structure, x represents an integer of 1 to 8, and y represents an integer of 3 to 17. ]

The compound represented by the general formula (1) is photolyzed by ultraviolet irradiation to generate a sulfonic acid that is a strong acid. It is also possible to use a sensitizer together and cause the polymerization initiator to decompose and sulfonic acid to be generated by using the sensitizer to absorb ultraviolet rays as a trigger.
Examples of the ring structure formed by combining R ₁ and R ₂ include 5-membered rings and 6-membered rings. Specific examples of the ring structure formed by combining R ₁ and R ₂ include succinimide structure, phthalimide structure, norbornene dicarboximide structure, naphthalene dicarboximide structure, cyclohexane dicarboximide structure, epoxy Examples thereof include a cyclohexene dicarboximide structure.
The ring structure may have an alkyl group, an alkyloxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, or the like as a substituent.

C _x F _y in the general formula (1) includes a linear alkyl group (RF1) in which a hydrogen atom is substituted with a fluorine atom, a branched alkyl group (RF2) in which a hydrogen atom is substituted with a fluorine atom, hydrogen Examples thereof include a cycloalkyl group (RF3) in which an atom is substituted with a fluorine atom, and an aryl group (RF4) in which a hydrogen atom is substituted with a fluorine atom.
Examples of the linear alkyl group (RF1) in which a hydrogen atom is substituted with a fluorine atom include a trifluoromethyl group (x = 1, y = 3), a pentafluoroethyl group (x = 2, y = 5), and hepta. Fluoro n-propyl group (x = 3, y = 7), nonafluoro n-butyl group (x = 4, y = 9), perfluoro n-hexyl group (x = 6, y = 13), and perfluoro n -An octyl group (x = 8, y = 17) etc. are mentioned.
Examples of the branched alkyl group (RF2) in which a hydrogen atom is substituted with a fluorine atom include a perfluoroisopropyl group (x = 3, y = 7) and a perfluoro-tert-butyl group (x = 4, y = 9). ), And a perfluoro-2-ethylhexyl group (x = 8, y = 17).
Examples of the cycloalkyl group (RF3) in which a hydrogen atom is substituted with a fluorine atom include a perfluorocyclobutyl group (x = 4, y = 7), a perfluorocyclopentyl group (x = 5, y = 9), Examples include a fluorocyclohexyl group (x = 6, y = 11) and a perfluoro (1-cyclohexyl) methyl group (x = 7, y = 13).
Examples of the aryl group (RF4) in which a hydrogen atom is substituted with a fluorine atom include a pentafluorophenyl group (x = 6, y = 5) and a 3-trifluoromethyltetrafluorophenyl group (x = 7, y = 7).
Of the C _x F _{y in} the general formula (1), from the viewpoint of availability and decomposability of the sulfonic acid ester portion, a linear alkyl group (RF1) or a branched alkyl group (RF2) is preferable. And an aryl group (RF4). More preferably, they are a linear alkyl group (RF1) and an aryl group (RF4). Particularly preferably, trifluoromethyl group (x = 1, y = 3), pentafluoroethyl group (x = 2, y = 5), heptafluoro n-propyl group (x = 3, y = 7), nonafluoro n- A butyl group (x = 4, y = 9), and a pentafluorophenyl group (x = 6, y = 5).

  Specific examples of the compound represented by the general formula (1) [Exemplary compounds D-1 to D-27] are listed below, but the present invention is not limited to these examples.

Among these, (D-23), (D-24), (D-25), (D-26), and (D-27) are preferable because high fixability is easily obtained in combination with a sensitizer. .
The said polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
Further, the content of the polymerization initiator in the curable liquid developer is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the cationic polymerizable liquid monomer. More preferably, they are 0.05 mass part or more and 1 mass part or less, More preferably, they are 0.1 mass part or more and 0.5 mass part or less.

[Toner particles]
The curable liquid developer of the present invention contains toner particles.
The toner particles preferably contain a binder resin and a colorant.
<Binder resin>
As the binder resin contained in the toner particles, a known binder resin can be used as long as it has fixability to an adherend such as paper or plastic film and is insoluble in the cationic polymerizable liquid monomer.
Here, the insolubility in the cationically polymerizable liquid monomer means that the binder resin to be dissolved is 1 part by mass or less with respect to 100 parts by mass of the cationically polymerizable liquid monomer at a temperature of 25 ° C.
Specific examples of the binder resin include resins such as epoxy resins, ester resins, (meth) acrylic resins, styrene- (meth) acrylic resins, alkyd resins, polyethylene resins, ethylene- (meth) acrylic resins, and rosin-modified resins. Can be mentioned. If necessary,
These can be used alone or in combination of two or more.
Although it does not specifically limit as content of binder resin, It is preferable that they are 50 mass parts or more and 1000 mass parts or less with respect to 100 mass parts of coloring agents.

[Colorant]
The colorant contained in the toner particles is not particularly limited, and all commercially available organic pigments, organic dyes, inorganic pigments, or pigments are dispersed in an insoluble resin or the like as a dispersion medium. Or those obtained by grafting a resin on the pigment surface can be used.
Examples of the pigment include W.W. Herbst, K.M. Examples include pigments described in Hunger “Industrial Organic Pigments”.
Specific examples of the pigment include, for example, the following ones exhibiting a yellow color.
C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; I. Bat yellow 1, 3, 20
Examples of those exhibiting red or magenta color include the following.
C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48: 2, 48: 3, 48: 4, 49, 50, 51, 52, 53, 54, 55, 57: 1, 58, 60, 63, 64, 68, 81: 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269; I. Pigment violet 19; C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35.
Examples of the pigment exhibiting blue or cyan include the following.
C. I. Pigment blue 2, 3, 15: 2, 15: 3, 15: 4, 16, 17; I. Bat Blue 6; C.I. I. Acid Blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton.
Examples of the green pigment include the following.
C. I. Pigment Green 7, 8, 36.
Examples of the orange pigment include the following.
C. I. Pigment Orange 66, 51.
Examples of black pigments include the following.
Carbon black, titanium black, aniline black.
Examples of white pigments include the following.
Basic lead carbonate, zinc oxide, titanium oxide, strontium titanate.
For the dispersion of the pigment in the toner particles, a dispersing means corresponding to the toner particle production method may be used. Examples of the apparatus that can be used as the dispersing means include, for example, a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, and a wet jet mill. There is.
It is also possible to add a pigment dispersant when dispersing the pigment. Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, a fatty acid An aromatic polyvalent carboxylic acid, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester, pigment derivative and the like can be mentioned. It is also preferable to use a commercially available polymer dispersant such as Solsperse series manufactured by Lubrizol.
Moreover, it is also possible to use the synergist according to various pigments as a pigment dispersion aid.
These pigment dispersant and pigment dispersion aid are preferably added in an amount of 1 part by weight to 50 parts by weight with respect to 100 parts by weight of the pigment.

[Charge control agent]
The curable liquid developer of the present invention may contain a charge control agent as necessary. Known charge control agents can be used.
Specific examples of the compound include the following.
Oils and fats such as linseed oil and soybean oil; alkyd resins, halogen polymers, aromatic polycarboxylic acids, acidic group-containing water-soluble dyes, aromatic polyamine oxidation condensates, cobalt naphthenate, nickel naphthenate, iron naphthenate, naphthene Metal soaps such as zinc oxide, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate, aluminum stearate, cobalt 2-ethylhexanoate; petroleum metal sulfonates, Sulfonic acid metal salts such as metal salts of sulfosuccinic acid esters; phospholipids such as lecithin and hydrogenated lecithin; salicylic acid metal salts such as t-butylsalicylic acid metal complex; polyvinylpyrrolidone resin, polyamide resin, sulfonic acid-containing resin, hydroxybenzoic acid Derivatives, etc.

[Charge aid]
In the present invention, the toner particles may contain a charge auxiliary agent as needed for the purpose of adjusting the chargeability of the toner particles. As the charge auxiliary agent, known ones can be used.
Specific compounds include zirconium naphthenate, cobalt naphthenate, nickel naphthenate, iron naphthenate, zinc naphthenate, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate. , Metal soaps such as aluminum stearate, aluminum tristearate and cobalt 2-ethylhexanoate; metal sulfonates such as petroleum metal sulfonates and metal salts of sulfosuccinates; phospholipids such as lecithin; t- Salicylic acid metal salts such as butylsalicylic acid metal complexes; polyvinylpyrrolidone resins, polyamide resins, sulfonic acid-containing resins, hydroxybenzoic acid derivatives, and the like.

[Sensitizer]
If necessary, a sensitizer may be added to the curable liquid developer of the present invention for the purpose of improving the acid generation efficiency of the polymerization initiator and increasing the photosensitive wavelength.
The sensitizer is not particularly limited as long as it sensitizes the polymerization initiator by an electron transfer mechanism or an energy transfer mechanism.
Specifically, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone, and Michlerketone, heterocycles such as phenothiazine and N-aryloxazolidinone A ring compound is mentioned.
The content of the sensitizer is appropriately selected according to the purpose, but is generally 0.1 parts by mass or more and 10 parts by mass or less with respect to 1 part by mass of the polymerization initiator, preferably 1 part by mass or more and 5 parts by mass or less.
Further, a sensitizing aid may be added to the curable liquid developer of the present invention for the purpose of improving the electron transfer efficiency or energy transfer efficiency between the sensitizer and the polymerization initiator.
Specifically, naphthalene compounds such as 1,4-dihydroxynaphthalene, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol, 1,4 Examples thereof include benzene compounds such as -dihydroxybenzene, 1,4-dimethoxybenzene, 1,4-diethoxybenzene, 1-methoxy-4-phenol, and 1-ethoxy-4-phenol.
The content of the sensitizer is appropriately selected according to the purpose, but is generally 0.1 parts by mass or more and 10 parts by mass or less, preferably 1 part by mass with respect to 1 part by mass of the sensitizer. Is 0.5 parts by mass or more and 5 parts by mass or less.

[Cation polymerization inhibitor]
A cationic polymerization inhibitor may be added to the curable liquid developer of the present invention.
Examples of the cationic polymerization inhibitor include alkali metal compounds and / or alkaline earth metal compounds, or amines.
Examples of the amines include alkanolamines, N, N-dimethylalkylamines, N, N-dimethylalkenylamines, N, N-dimethylalkynylamines and the like.
Specifically, triethanolamine, triisopropanolamine, tributanolamine, N-ethyldiethanolamine, propanolamine, n-butylamine, sec-butylamine, 2-aminoethanol, 2-methylaminoethanol, 3-methylamino-1 -Propanol, 3-methylamino-1,2-propanediol, 2-ethylaminoethanol, 4-ethylamino-1-butanol, 4- (n-butylamino) -1-butanol, 2- (t-butylamino) ) Ethanol, N, N-dimethylundecanolamine, N, N-dimethyldodecanolamine, N, N-dimethyltridecanolamine, N, N-dimethyltetradecanolamine, N, N-dimethylpentadecanol Amine, N, N-dimethylnonadecylami N, N-dimethylicosylamine, N, N-dimethyleicosylamine, N, N-dimethylhenicosylamine, N, N-dimethyldocosylamine, N, N-dimethyltricosylamine, N, N- Dimethyltetracosylamine, N, N-dimethylpentacosylamine, N, N-dimethylpentanolamine, N, N-dimethylhexanolamine, N, N-dimethylheptanolamine, N, N-dimethyloctanolamine, N, N-dimethylnonanolamine, N, N-dimethyldecanolamine, N, N-dimethylnonylamine, N, N-dimethyldecylamine, N, N-dimethylundecylamine, N, N-dimethyldodecylamine, N , N-dimethyltridecylamine, N, N-dimethyltetradecylamine, N, N-dimethyl Pentadecyl amine, N, N-dimethyl hexadecylamine, N, N-dimethyl-hepta-decyl amine, N, N-dimethyl octadecyl amine. In addition to these, quaternary ammonium salts and the like can also be used. As the cationic polymerization inhibitor, a secondary amine is particularly preferable.
The content of the cationic polymerization inhibitor is preferably 1 ppm or more and 5000 ppm or less on a mass basis in the curable liquid developer.

[Radical polymerization inhibitor]
A radical polymerization inhibitor may be added to the curable liquid developer of the present invention.
For example, in the case of a curable liquid developer containing a vinyl ether compound, the polymerization initiator may be slightly decomposed during storage over time to form a radical compound, which may cause polymerization due to the radical compound. It is good to add to.
Applicable radical polymerization inhibitors include, for example, phenolic hydroxyl group-containing compounds, quinones such as methoquinone (hydroquinone monomethyl ether), hydroquinone, 4-methoxy-1-naphthol, hindered amine antioxidants, 1,1-diphenyl -2-picrylhydrazyl free radical, N-oxyl free radical compounds, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenol antioxidants, ascorbic acids, zinc sulfate, thiocyanates, Thiourea derivatives, various sugars, phosphate antioxidants, nitrites, sulfites, thiosulfates, hydroxylamine derivatives, aromatic amines, phenylenediamines, imines, sulfonamides, urea derivatives, oximes, dicyandiamide And polyalkyl Polycondensates down polyamine, sulfur-containing compounds such as phenothiazine, complexing agent to tetraazacyclododecane Anne based Len (TAA), and the like hindered amines.
From the viewpoint of preventing thickening of the curable liquid developer, preferably, a phenolic hydroxyl group-containing compound, an N-oxyl free radical compound, a 1,1-diphenyl-2-picrylhydrazyl free radical, a phenothiazine, a quinone, Hindered amines. More preferred are N-oxyl free radical compounds.
The content of the radical polymerization inhibitor is preferably 1 ppm or more and 5000 ppm or less on the mass basis in the curable liquid developer.

[Other additives]
In addition to the above description, the curable liquid developer of the present invention may be added in various known manners depending on the purpose of improving the compatibility of the recording medium, storage stability, image storability, and other performances as necessary. An agent may be used. For example, surfactants, lubricants, fillers, antifoaming agents, ultraviolet absorbers, antioxidants, anti-fading agents, antifungal agents, rust preventives and the like can be mentioned, and these can be appropriately selected and used.

In the present invention, the method for producing the curable liquid developer is not particularly limited, and examples thereof include known methods such as a coacervation method and a wet pulverization method.
As a general production method, a pigment, a binder resin, other additives, and a dispersion medium are mixed and pulverized using a bead mill or the like to obtain a dispersion of toner particles. A production method for obtaining a liquid developer by mixing the obtained dispersion of toner particles, a polymerization initiator, a cationic polymerizable liquid monomer, and the like can be exemplified.
Details of the coacervation method are described in, for example, JP-A No. 2003-241439, International Publication No. 2007/000974, or International Publication No. 2007/000975.
In the coacervation method, a pigment, a resin, a solvent that dissolves the resin, and a solvent that does not dissolve the resin are mixed, the solvent that dissolves the resin is removed from the mixed solution, and the solution in a dissolved state is obtained. By precipitating the resin, the toner particles embedded with the pigment can be dispersed in a solvent that does not dissolve the resin.
On the other hand, details of the wet pulverization method are described in, for example, International Publication No. 2006/126666 or International Publication No. 2007/108485.
In the wet pulverization method, the toner particles are electrically pulverized by kneading the pigment and the binder resin at a melting point of the binder resin or higher and then dry pulverizing the resulting pulverized material in an electrically insulating medium. Can be dispersed in.
In the present invention, such a known method can be used.
The toner particles preferably have a volume average particle diameter of 0.05 μm or more and 5 μm or less, more preferably 0.05 μm or more and 1 μm or less from the viewpoint of obtaining a high-definition image.
In the present invention, the toner particle concentration in the curable liquid developer can be arbitrarily adjusted according to the image forming apparatus to be used, but is preferably about 1% by mass to 70% by mass.

[Physical properties of curable liquid developer]
The curable liquid developer of the present invention is preferably prepared and used so as to have the same physical properties as those of a normal liquid developer.
The volume resistivity of the curable liquid developer is preferably 1 × 10 ¹⁰ Ω · cm or more and 1 × 10 ¹³ Ω · cm or less in that the potential of the electrostatic latent image is not lowered. In the present invention, it is possible to prepare a curable liquid developer satisfying the above physical property values while obtaining high curability.

[Image forming apparatus]
The curable liquid developer of the present invention can be suitably used in general electrophotographic image forming apparatuses.
Hereinafter, an example of an embodiment in which the curable liquid developer of the present invention is applied to an electrophotographic image forming apparatus (hereinafter simply referred to as an image forming apparatus) that is a liquid image forming apparatus will be described.
FIG. 1 is a schematic configuration diagram of a main part of an image forming apparatus according to the present embodiment.
The image forming apparatus includes image forming units 50C, 50M, 50Y, and 50K, primary transfer units 60C, 60M, 60Y, and 60K, a secondary transfer unit 30, and a developer curing unit 90.
The image forming units 50C, 50M, 50Y, and 50K develop latent images with cyan (C) liquid developer, magenta (M) liquid developer, yellow (Y) liquid developer, and black (K) liquid developer, respectively. It has a function to do.
The image forming units 50C, 50M, 50Y, and 50K supply the developer from the developer containers 10C, 10M, 10Y, and 10K that store the liquid developers to the developing units 51C, 51M, 51Y, and 51K. The pumps 13C, 13M, 13Y, and 13K and the photoconductors 52C, 52M, 52Y, and 52K are configured such that a charger, an exposure unit, a cleaning unit, and a static eliminator are arranged around the photoconductors.
Since the image forming units 50C, 50M, 50Y, and 50K have the same configuration, the image forming unit 50C will be described below.

FIG. 2 is a sectional view of the image forming unit 50C. A charging unit 57C, an exposure unit 56C, a developing unit 51C, a primary transfer unit 60C (FIG. 1), a recovery blade 59C, and a charge eliminating unit 58C are arranged along the rotation direction of the photoconductor 52C. The photoconductor 52C is a cylindrical shape. It has a substrate and a photosensitive layer formed on the outer peripheral surface thereof, and can rotate around a central axis. In this embodiment, it rotates clockwise. The surface of the photoreceptor 52C is formed of amorphous silicon (a-Si). An organic photoreceptor (OPC) or the like can also be used as the material of the photoreceptor.
The charging unit 57C is a device for charging the photoconductor 52C. Either a corotron charger or a roller charger can be used.
The exposure unit 56C has a semiconductor laser, a polygon mirror, an F-θ lens, and the like, and irradiates the modulated laser onto the charged photoconductor 52C to form a latent image. As the laser light source, a light emitting diode (LED) or an organic light emitting diode (OLED) can be arranged.
The neutralization unit 58C is a device for neutralizing the photoreceptor 52C. Either a corona discharge charger or a roller contact charger can be used.
The collection blade 59C is composed of a rubber part made of urethane rubber or the like that comes into contact with the surface of the photoreceptor 52C, and a plate made of metal or the like that supports the rubber part, and scrapes the liquid developer remaining on the photoreceptor 52C into the collection unit 12C. Drop and remove.
The developing unit 51C includes a developing roller 53C, a concentration roller 54C, a cleaning roller 55C, and a film forming counter electrode 11C.
The developing roller 53C is a cylindrical member, and rotates in the opposite direction of the photoconductor 52C around the central axis as shown in FIG. The developing roller 53C is provided with an elastic body such as conductive urethane rubber, a resin layer, and a rubber layer on the outer peripheral portion of a metal inner core such as iron.
The film-forming counter electrode 11C is disposed with a gap with the developing roller 53C of at least 100 μm or more and is made of a metal member.
The concentration roller 54C is a cylindrical member, and rotates in the opposite direction of the developing roller 53C as shown in FIG. 2 around the central axis. The concentration roller 54C is made of metal such as iron.
The cleaning roller 55C is a cylindrical member and rotates about the central axis in the opposite direction of the developing roller 53C as shown in FIG.
The developer container 10C stores a cyan liquid developer for developing the latent image formed on the photoreceptor 52C. From the developer container 10C, the liquid developer whose density has been adjusted is supplied to the developing unit 51C through a communication pipe in which the developer supply pump 13C is arranged, and excess developer is supplied through a connecting pipe in which the developer collection pump 14C is arranged. Return to the developer container 10C. Developer container 10C
The toner particle concentration in the internal liquid developer is adjusted to at least 2% by mass or more.
The liquid developer whose toner particle concentration is adjusted is supplied between the rotating developing roller 53C and the film-forming counter electrode 11C, and a bias is set between the developing roller 53C and the film-forming counter electrode 11C. Is coated with a liquid developer. The bias can be set to at least 100 V and can be set up to the discharge limit.
The surplus of the supplied liquid developer is recovered from the recovery unit 12C through a communication pipe provided with a recovery pump, sent to a recovery tank (not shown), and reused.

The primary transfer units 60C, 60M, 60Y, and 60K include the intermediate transfer belt 40, primary transfer rollers 61C, 61M, 61Y, and 61K, and photoconductors 52C, 52M, 52Y, and 52K. The intermediate transfer belt 40 is an endless belt stretched between a belt driving roller and a driven roller, and is rotationally driven while being in contact with the photoreceptors 52C, 52M, 52Y, and 52K.
On the intermediate transfer belt 40, the primary transfer units 60C, 60M, 60Y, and 60K including the intermediate transfer belt 40, the primary transfer rollers 61C, 61M, 61Y, and 61K and the photoconductors 52C, 52M, 52Y, and 52K are used. The four color liquid developers are sequentially transferred to each other to form a full-color image.
The secondary transfer unit 30 includes a belt driving roller, a secondary transfer roller 31, a pre-wet roller 20, and a pre-wet counter roller 21, and is formed with a single color liquid developer image or a full color liquid developer formed on the intermediate transfer belt 40. The image is transferred to a recording medium 80 such as paper.
The pre-wet roller 20 is a cylindrical member and rotates about the central axis in the opposite direction of the intermediate transfer belt 40 as shown in FIG.
The pre-wet roller 20 is fed from a carrier tank (not shown) to form a carrier film of 1.0 μm or less on the surface, and then a monochromatic liquid developer image or full-color liquid developer formed on the intermediate transfer belt 40. The pre-wet roller 20 is brought into contact with the agent image to adjust the liquid film amount of the single color liquid developer image or the full color liquid developer image.
The developer curing unit 90 cures a reactive functional group by irradiating the monochromatic liquid developer image or full color liquid developer image transferred onto the recording medium 80 with light such as ultraviolet rays. The curing unit is composed of an LED lamp, but is not limited to an LED as long as it can irradiate ultraviolet rays, and a heating device, an EB irradiation device, or the like can also be used.

[light source]
The curable liquid developer of the present invention is given energy promptly after transfer to a recording medium, and the image is fixed by being cured.
The energy source used in the present invention is not particularly limited, but ultraviolet rays are preferably used. Here, as a light source for irradiating ultraviolet rays, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a hot cathode tube, a black light, an LED (light emitting diode), and the like are applicable. A strip-shaped metal halide lamp, a cold cathode tube, a hot cathode tube, a mercury lamp or black light, and an LED are preferable.
The dose of ultraviolet rays is preferably 0.1 mJ / cm ² or more 1000 mJ / cm ² or less.

The measurement method used in the present invention will be described below.
<Measurement method of viscosity>
In the present invention, the viscosity is measured by a rotational rheometer method.
Specifically, using a viscoelasticity measuring device (Physica MCR300, manufactured by Anton Paar Co., Ltd.), measurement is performed as follows.
About 2 mL of the sample is filled in a measuring apparatus equipped with a cone plate type measuring jig (75 mm diameter, 1 °) and adjusted to 25 ° C. The viscosity is measured while continuously changing the shear rate from 1000 s ⁻¹ to 10 s ^−1, and the value at 10 s ⁻¹ is taken as the viscosity.

<Structural analysis>
The structure of the compound is determined using a nuclear magnetic resonance apparatus ( ¹ H-NMR) and an FT-IR spectrum.
The apparatus and measurement method used for the measurement are described below.
(I) ¹ H-NMR
Measuring apparatus: FT NMR apparatus JNM-ECA400 (manufactured by JEOL Ltd.)
Measurement frequency: 500 MHz
Pulse condition: 10 μs
Frequency range: 10330Hz
Integration count: 16 times Measurement temperature: 25 ° C
A sample of 50 mg is put into a sample tube having an inner diameter of 5 mm, deuterated chloroform (CDCl ₃ ) is added as a solvent, and this is dissolved at 25 ° C. to prepare a measurement sample. It measured on the said conditions using the said measurement sample.
(Ii) FT-IR spectrum measuring apparatus: Spectrum One (manufactured by Perkin-Elmer)
Measuring method: single reflection ATR method Range Start: 4000 cm ⁻¹
End: 400 cm ⁻¹ (ATR crystal of KRS-5)
Scan number: 40
Resolution: 4.00 cm ⁻¹
Advanced: With CO ₂ / H ₂ O correction 0.01 g of sample is precisely weighed on the ATR crystal, and the sample is pressurized with a pressure arm. The sample was measured under the above conditions.

Hereinafter, the curable liquid developer will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.
In the following description, unless otherwise specified, “part” and “%” mean “part by mass” and “% by mass”, respectively.

<Synthesis example of cationic polymerizable liquid monomer>
(Synthesis of Exemplary Compound A-13)

Di-μ-chlorobis (1,5-cyclooctadiene) diiridium (I) [Ir (cod) Cl] ₂ (0.15 mg, 0.2 mmol) and potassium carbonate (13.5 g, 98 mm)
ol) to a toluene (40.0 ml) mixture, 1,12-octadecanediol (6.73 g, 24.7 mmol) and vinyl acetate (16 g, 186 mmol) shown in starting material 1 are added, and the mixture is added under an argon atmosphere. Stir at 6 ° C. for 6 hours. When the reaction solution was analyzed by gas chromatography, the conversion rate of starting material 1 was 93%, and a bifunctional vinyl ether monomer represented by compound A-13 was produced at a yield of 55%. The organic phase and the aqueous phase were separated using a separatory funnel, and the organic phase was purified by column, concentrated under reduced pressure, and dried to obtain Compound A-13 (weight average molecular weight: 338.6). The obtained compound was a slightly brown transparent viscous liquid. It was confirmed by FT-IR measurement of Compound A-13 that the peak derived from the hydroxyl group disappeared.

<Example 1>
(Production of toner particles)
In a separable flask, 25 parts of Nucrel N1525 (ethylene-methacrylic acid resin, manufactured by Mitsui DuPont Polychemical Co., Ltd.) and 75 parts of dodecyl vinyl ether (Exemplary Compound B-1) are charged and stirred at 200 rpm using a three-one motor. However, the temperature was raised to 130 ° C. in an oil bath over 1 hour. After being held at 130 ° C. for 1 hour, it was gradually cooled at a temperature drop rate of 15 ° C. per hour to prepare a binder resin dispersion. The obtained binder resin dispersion was a white paste.
59.40 parts of the binder resin dispersion, pigment blue 15: 3 (4.95 parts) as a pigment, 0.20 parts of aluminum tristearate as a charge auxiliary agent, and 35.45 parts of dodecyl vinyl ether, 0.5 mm in diameter The zirconia beads are filled into a planetary bead mill (Classic Line P-6, manufactured by Fritsch) and pulverized at 200 rpm at room temperature for 4 hours to contain 80.00 parts of dodecyl vinyl ether (Exemplary Compound B-1). A toner particle dispersion (solid content: 20% by mass) was obtained.
The toner particles contained in the obtained toner particle dispersion had a volume average particle size of 0.85 μm [dynamic light scattering method (DLS) particle size distribution measuring device, trade name: Nanotrack 150, manufactured by Nikkiso Co., Ltd. Measured at].
(Preparation of curable liquid developer)
10.00 parts of the toner particle dispersion, 0.10 parts of hydrogenated lecithin (Resinol S-10, manufactured by Nikko Chemicals Co., Ltd.) as a charge control agent, and the synthesized compound A-13 as a cationic polymerizable liquid monomer. 00 parts, 12.00 parts of Exemplified Compound B-1 used in the production of the toner particle dispersion as a viscosity adjusting monomer, and then Exemplified Compound D-26 (0.30 part) as a polymerization initiator, sensitization As a sensitizer, 0.50 part of 2,4-diethylthioxanthone and 0.50 part of 1,4-diethoxynaphthalene as a sensitizer were mixed to obtain a curable liquid developer. The obtained curable liquid developer contains 8.00 parts for the preparation of the toner particle dispersion, 12.00 parts for the viscosity adjustment, and 20.00 parts in total for the exemplified compound B-1.

<Evaluation>
The curable liquid developer was evaluated by the following evaluation method. The results are shown in Table 1.
(Image formation)
An image was formed on the obtained curable liquid developer on a polyethylene terephthalate (PET) sheet using the image forming apparatus shown in FIGS. 1 and 2, and the quality of the obtained image was confirmed.
The specific procedure is as follows.
(1) The developing roller 53, the photosensitive member 52, and the primary transfer roller 61 are separated from each other and driven to rotate in the direction of the arrow in FIG. The rotational speed at this time was 250 mm / sec.
(2) The developing roller 53 and the photosensitive member 52 were brought into contact with each other with a pressing pressure of 5 N / cm, and a bias was set using a DC power source. Since the developing bias is preferably in the range of 100 to 400V, it is set to 200V.
(3) The photosensitive member 52 and the primary transfer roller 61 were brought into contact with each other with a constant pressing pressure, and a bias was set using a DC power source. The transfer bias was 1000V.
(4) The secondary transfer unit 30 and the secondary transfer roller 31 were brought into contact with each other with a constant pressing pressure, and a bias was set using a DC power source. The transfer bias was 1000V.
(5) A curable liquid developer is supplied to the developer container 10C, and a polyethylene terephthalate (PET) sheet (manufactured by Teijin Chemicals, Panlite: PC-2151) is formed on a part of an OK top coat (manufactured by Oji Paper) as a recording medium 80. , With a thickness of 0.3 mm), a solid image of full-surface printing was formed on a PET sheet and evaluated.
Image formation was performed in the initial stage, 1 day, and 3 days after the image forming apparatus was cleaned and the curable liquid developer was set. During this period, the inside of the apparatus was not cleaned. The quality of the image was confirmed visually.
(Evaluation criteria)
5: A uniform solid image with high density was obtained 4: Density unevenness and image blur were not observed, and a good image was obtained 3: Some density unevenness or some image blur was observed, A generally good image was obtained 2: Vigorous density unevenness and image blurring occurred, an insufficiently developed part was observed, and cleaning in the apparatus was necessary 1: almost no development was possible, and cleaning in the apparatus was not possible Was necessary

(Fixability)
In an environment of room temperature of 25 ° C. and humidity of 50%, a curable liquid developer was dropped on a polyethylene terephthalate film (manufactured by Teijin Chemicals, Panlite: PC-2151, thickness 0.3 mm), and a wire bar (No. 6). ) Bar coating is performed using [Supplier: Matsuo Sangyo Co., Ltd.] (the formed film thickness is 8.0 μm), and irradiation is performed by irradiating light with a wavelength of 365 nm with a high-pressure mercury lamp having a lamp output of 120 mW / cm ^2. A film was formed. The irradiation light quantity when the surface was completely cured without tack (adhesiveness) was measured and evaluated according to the following criteria.
5: 100 mJ / cm ²
4: 200 mJ / cm ²
3: 400 mJ / cm ²
2: 1,000 mJ / cm ²
1: Not cured at 2,000 mJ / cm ^{2 In the} above initial stage, one day later, three days later, the image quality and the fixability rank were all 3 or more. These evaluation results are shown in Table 1.

<Example 2>
In Example 1 (preparation of toner particles), a toner particle dispersion was prepared using Compound A-13 instead of Dodecyl Vinyl Ether (Exemplary Compound B-1). Furthermore, also in (Preparation of curable liquid developer), a curable liquid developer was prepared using Compound A-13 instead of Exemplary Compound B-1. In Example 2, all of the cationically polymerizable liquid monomer was Compound A-13.

<Examples 3-12, Comparative Examples 1-4>
A curable liquid developer was prepared in the same manner as in Example 1 except that the toner particle dispersion used in Example 1 was used and a polymerization initiator and a cationic polymerizable liquid monomer were blended so as to have the composition shown in Table 1. Obtained.
In Examples 7 to 12 and Comparative Examples, CPI-210S (manufactured by San Apro Co., Ltd .; triarylsulfonium salt-based polymerization initiator, expressed as D-28) was used as the polymerization initiator, and the addition amount was 1.00. The part.
Evaluation similar to Example 1 was performed using the thus obtained curable liquid developer. The evaluation results are shown in Table 1.

As shown in the examples of Table 1, by using a curable liquid developer in which the compound represented by the formula (A) is used as the main component of the cationic polymerizable liquid monomer, the fixability can be obtained even in a humidity environment. Excellent images with excellent density and no unevenness were obtained. Further, even when an image was formed after one day and three days, there was little deterioration in image quality. This means that contamination of the members inside the apparatus is prevented.
When Example 7 and Example 8 were compared, Example 7 with a higher content of the compound represented by the formula (A) in the cationically polymerizable liquid monomer showed better image quality after 3 days.
Further, the carbon number of the alkane chain of the compound represented by the formula (A) used in Example 8 was 18, whereas the carbon of the alkane chain of the compound used in Example 9 and Example 10 was used. The number was 12, and in Example 8 with a larger number of carbons, the image quality was less deteriorated after one day than in Examples 9 and 10.
In Example 11 and Example 12, the compound represented by the formula (A) used an alkane chain having about 50 carbon atoms. However, since the image density at the initial stage was slightly thin, image formation was evaluated. It became 3.
This is probably because the viscosity of the curable liquid developer was high, so that the electrophoretic speed of the toner particles was reduced and the amount of toner particles adhering to the charging roller was reduced.
The viscosity of the curable liquid developers of Examples 11 and 12 was 100 mPa · s, whereas the viscosity of the curable liquid developers of other Examples was 5 to 20 mPa · s. Therefore, the upper limit of the carbon number of the alkane chain of the compound represented by the formula (A) is considered to be about 50.
The compounds represented by formula (A) used in Example 9 and Example 10 have the same number of carbons in the alkane chain and the same molecular weight.
The compound represented by the formula (A) used in Example 9 is a carbon atom other than the terminal of the carbon atom in which at least one vinyl ether group in the formula (A) forms the alkane chain in the formula (A). Compound A-1 bonded to is used.
On the other hand, the compound represented by the formula (A) used in Example 10 was obtained by using the compound A-2 having vinyl ether groups at both ends of the carbon atom forming the alkane chain in the formula (A). Yes.
Regarding fixing property, Example 9 using a compound having a vinyl ether group in addition to the terminal of the carbon atom forming the alkane chain was better. This is presumably because the SP value of Compound A-1 was smaller than the SP value of Compound A-2 and it was difficult for moisture to be adsorbed. When the SP value was calculated by the Fedors estimation method, the SP value of compound A-1 was 8.27, and the SP value of compound A-2 was 8.36.
In Comparative Example 1, bifunctional vinyl ether (Exemplary Compound B-21) having 10 carbon atoms in the alkane chain was used as the main component of the cationic polymerizable liquid monomer. On the other hand, in Comparative Example 2, bifunctional vinyl ether (Exemplary Compound B-15) having an alkane chain having 8 carbon atoms was used as the main component of the cationically polymerizable liquid monomer. Comparative Example 1 and Comparative Example 2 were not inferior in fixability as compared with the Examples, but when an image was formed after 1 day, the image quality was significantly lowered. The members inside the apparatus were contaminated and needed to be cleaned. When the members inside the apparatus were cleaned, the image immediately after that was good.
Although the carbon number of the alkane chain of the compounds used in Comparative Example 3 and Comparative Example 4 is 12 or more, both are monofunctional vinyl ether compounds, and the fixability is remarkably lowered.

  According to the present invention, the volatilization of the vinyl ether compound used in the curable liquid developer is extremely low, the contamination of the members inside the apparatus is prevented and high image quality is maintained for a long time, and excellent fixability even in a humidity environment A curable liquid developer exhibiting the following can be provided.

10C, 10M, 10Y, 10K: developer container, 11C: film-forming counter electrode, 12C: recovery unit, 13C, 13M, 13Y, 13K: developer supply pump, 14C: developer recovery pump, 20: pre-wet roller, 21: Pre-wet facing roller, 30: Secondary transfer unit, 31: Secondary transfer roller, 40: Intermediate transfer belt, 50C, 50M, 50Y, 50K: Image forming unit, 51C, 51M, 51Y, 51K: Development unit 52C, 52M, 52Y, 52K: photoconductor, 53C: developing roller, 54C: concentration roller, 55C: cleaning roller, 56C: exposure unit, 57C: charging unit, 58C: static elimination unit, 59C: recovery blade, 60C, 60M, 60Y, 60K: primary transfer unit, 61C, 61M, 61Y, 61K: primary Continuous roller, 80: recording medium, 90: developer curing unit

Claims (6)

A curable liquid developer containing toner particles, a polymerization initiator, and a cationic polymerizable liquid monomer,
The curable liquid developer, wherein the cationic polymerizable liquid monomer contains a compound represented by the following formula (A).
(R—CH═CH—O—) _n —C _m H _{(2m + 2-n)} Formula (A)
[In the formula (A), m represents an integer of 12 or more and 50 or less, n represents an integer of 2 or more, and R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ] In the formula (A), at least one vinyl ether group represented by the following formula (A1) is carbon other than the terminal of the carbon atom forming the alkane chain represented by the following formula (A2) in the formula (A). The curable liquid developer according to claim 1, which is bonded to an atom.
(R—CH═CH—O—) _n formula (A1)
_{-C m H (2m + 2-} n) Formula (A2)
[In the formula (A1) and the formula (A2), m represents an integer of 12 to 50, n represents an integer of 2 or more, and R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ]   The curable liquid developer according to claim 1, wherein m is an integer of 12 or more and 25 or less in the formula (A).   The curable liquid developer according to claim 1, wherein in the formula (A), m is an integer of 18 or more and 25 or less.   The content of the compound represented by the formula (A) is 70 parts by mass or more and 100 parts by mass or less in 100 parts by mass of the cationic polymerizable liquid monomer. A curable liquid developer. The curable liquid developer according to claim 1, wherein the polymerization initiator contains a compound represented by the following general formula (1).

[In General Formula (1), R ₁ and R ₂ are bonded to each other to form a ring structure, x represents an integer of 1 to 8, and y represents an integer of 3 to 17. ]