WO2018092902A1 - Curable liquid developer - Google Patents

Abstract

The purpose of the present invention is to provide a toner charge control agent capable of achieving a low curing inhibition property and high electrophoretic mobility, and provide a curable liquid developer having a highly curable property and capable of responding to increased processing speed of an image forming device. The curable liquid developer contains toner particles insoluble in a cationic polymerizable liquid monomer, a polymerization initiator, and a cationic polymerizable monomer, and is characterized by containing a high molecular compound having a monometric unit represented by a specific structural formula.

Description

Curing type liquid developer

The present invention relates to a curable 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 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 fixed to the recording medium. (Fixing step) to obtain a printed matter.
In this case, the developer is a liquid obtained by dispersing colored particles composed of a material containing a colorant such as a pigment and a binder resin in a dry state, and a liquid in which the colored particles are dispersed in an electrically insulating liquid as a carrier liquid. Broadly divided into developers.
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. Since the liquid developer hardly causes aggregation of colored particles in the developer, fine toner particles can be used. Therefore, the liquid developer can easily obtain characteristics excellent in fine line image reproducibility and gradation reproducibility. Development of a high-quality, high-speed digital printing apparatus using an electrophotographic technique using a liquid developer, which takes advantage of these excellent features, is becoming popular. 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-based 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, in that case, there is a possibility that the vapor of the organic solvent may be released to the outside of the apparatus, and a great amount of energy is required, which is not necessarily preferable from the viewpoint of environment and energy saving.
As a countermeasure against this, a method of curing an electrically insulating liquid by polymerization has been proposed. As a curable liquid developer, a monomer or oligomer having a reactive functional group is used as an electrically insulating liquid, and a polymerization initiator is further dissolved. Examples of the curable liquid developer include those that are cured by irradiating light such as ultraviolet rays to react with a reactive functional group, and can cope with high speed. Such curable liquid developers are proposed in Patent Documents 1 and 2. In Patent Documents 1 and 2, the above-mentioned problems are solved by combining an electrically insulating liquid with a high-resistance cationic polymerizable monomer such as vinyl ether and a curing initiator to form a curable liquid developer. .
On the other hand, development of a toner charge control agent capable of achieving high electrophoretic mobility has been demanded due to the recent increase in process speed.
Known toner charge control agents for negatively charging toner particles include lecithin (for example, Patent Documents 1 to 3) and barium sulfonate-based control agents such as barium petronate (for example, Patent Documents 1 and 3).

Japanese Patent No. 3442406 Japanese Patent Laying-Open No. 2015-127812 Japanese Patent No. 3267716

However, when the conventional toner charge control agent as described above is used for a curable liquid developer, these materials have a property of inhibiting cationic polymerization, so that more polymerization initiator and energy are required for curing. There was a problem of need.
In order to solve the above problems, development of a toner charge control agent that has a small polymerization inhibition (curing inhibition) and can achieve high electrophoretic mobility has been demanded.
Accordingly, the present invention provides a toner charge control agent that has a small curing inhibition property and can achieve a high electrophoretic mobility, has a high curability, and can be used to increase the process speed of an image forming apparatus. Is to provide.

The present invention is a curable liquid developer comprising a cationic polymerizable liquid monomer, a polymerization initiator, and toner particles insoluble in the cationic polymerizable liquid monomer,
A curable liquid developer comprising a polymer compound having at least one of monomer units represented by the following formulas (1) and (2).

[In the formulas (1) and (2), R ₁ to R ₄ each independently represents a hydrogen atom or an alkyl group, A and B represent a divalent linking group, and X ⁻ represents a halogen atom. An ion or an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure is represented, and Y ⁻ represents an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure. ]

According to the present invention, it is possible to provide a curable liquid developer that has high curability and can cope with an increase in the process speed of the image forming apparatus.

In the present invention, the description of “XX or more and XX or less” or “XX to XX” representing a numerical range means a numerical range including a lower limit and an upper limit as end points unless otherwise specified.
Moreover, a monomer unit means the form which the monomer substance in a polymer or resin reacted.
Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.
The curable liquid developer of the present invention (hereinafter also simply referred to as a liquid developer) is a curable liquid developer containing a cationic polymerizable liquid monomer, a polymerization initiator, and toner particles insoluble in the cationic polymerizable liquid monomer. There,
It contains a polymer compound having at least one of monomer units represented by the following formulas (1) and (2).

[In the above formulas (1) and (2), R ₁ to R ₄ each independently represents either a hydrogen atom or an alkyl group, A and B represent a divalent linking group, and X ⁻ represents a halogen atom. An ion or an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure is represented, and Y ⁻ represents an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure. ]

Hereinafter, the monomer unit represented by Formula (1) or Formula (2) and the polymer compound having the monomer unit will be described in detail.
The monomer unit represented by Formula (1) or Formula (2) has excellent positive charge acceptability.
Therefore, by dissolving or dispersing the polymer compound having the monomer unit in the cationic polymerizable liquid monomer, the polymer compound having the monomer unit is adsorbed on the toner particles, and the toner particles are positively charged. Accept. As a result, the toner particles are negatively charged. That is, the polymer compound having the monomer unit acts as a toner charge control agent for negatively charging the toner particles.
On the other hand, when a cationically polymerizable monomer such as vinyl ether is polymerized and cured using a polymerization initiator or the like, the presence of a basic compound such as moisture or amine in the system inhibits the polymerization reaction and inhibits curing. In addition, certain additives and impurities can inhibit the absorption of light into the polymerization initiator and sensitizer, and can inhibit the curing process by inhibiting the energy transfer process from the sensitizer to the polymerization initiator. It is also possible to become.
In liquid developers, phospholipids such as lecithin, metal soaps such as naphthenic acid metal salts, metal sulfonates, and the like have been used for a long time as toner charge control agents for negatively charging toner particles. However, when these compounds are used in a cationic polymerizable liquid developer, there is a problem that they have a high property of inhibiting cationic polymerization and cause curing inhibition. The cause of these toner charge control agents causing cure inhibition has not been clarified, but it is expected that they are caused by any one or some combination of the above inhibition factors.

It has been found that the polymer compound having at least one of the monomer units represented by the above formulas (1) and (2) has a smaller property of inhibiting cationic polymerization than the conventional toner charge control agent, The present invention has been reached.
That is, by using a polymer compound having at least one of the monomer units represented by the above formulas (1) and (2) as a toner charge control agent of a cationic polymerizable liquid developer, A liquid developer having high electrophoretic mobility of particles and high curability can be provided.

In the above formulas (1) and (2), the alkyl group for R ₁ is preferably an alkyl group having 1 to 4 carbon atoms. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group.
R ₁ in the above formulas (1) and (2) can be arbitrarily selected from the substituents and hydrogen atoms listed above, but from the viewpoint of production (polymerizability) of the polymer compound, a hydrogen atom and a methyl group Is preferred.

In the above formulas (1) and (2), the alkyl group in R ₂ to R ₄ is preferably an alkyl group having 1 to 30 carbon atoms, and more preferably an alkyl group having 1 to 18 carbon atoms. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an n-octyl group, a 2-ethylhexyl group, a dodecyl group, and an octadecyl group. These alkyl groups may be further substituted and may be bonded to each other to form a ring.

In the above formulas (1) and (2), A is a divalent linking group that bonds the polymer main chain to the quaternary ammonium moiety, and includes an alkylene group, an arylene group, an aralkylene group, a-COOR ₅ -b, a-CONHR ₅ -b or a-OR ₅ -b (wherein a represents the bonding site with the carbon atom to which R ₁ is bonded, b represents the bonding site with the quaternary ammonium moiety, and R ₅ represents alkylene. A group or an arylene group).
The alkylene group in the linking group A may be either linear or branched, and is preferably an alkylene group having 1 to 4 carbon atoms. For example, a methylene group, ethylene group, propylene group, various butylene groups, etc. are mentioned.
Examples of the arylene group in the linking group A include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, And naphthalene-2,6-diyl group.
Examples of the aralkylene group in the linking group A include an aralkylene group having 7 to 15 carbon atoms.
The linking group A is a-COOR ₅ -b, a-CONHR ₅ -b, or a-OR ₅ -b (wherein, a represents a bonding site to the carbon atom to which R ₁ is bonded, and b represents a quaternary ammonium represents a binding site to site, for R ₅ represents an alkylene group or an arylene group), as the alkylene group for R _5, it may be straight-chain or branched, having 1 to 4 carbon atoms An alkylene group is preferred. For example, a methylene group, ethylene group, propylene group, various butylene groups, etc. are mentioned.
Examples of the arylene group for R ₅ include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a naphthalene-1,4-diyl group, and a naphthalene-1,5-diyl group. And naphthalene-2,6-diyl group.

The linking group A may be further substituted, and the substitution is not particularly limited as long as it does not significantly lower the charging characteristics of the polymer compound and the curability of the liquid developer.
The linking group A is not particularly limited as described above, but is preferably a-COOR ₅ -b from the viewpoint of availability of raw materials and ease of production.

In the above formula (2), B is a quaternary ammonium sites and its counter anion Y ^- is a divalent linking group that binds, for example, alkylene groups or arylene groups.
The alkylene group in the linking group B may be linear or branched, and is preferably an alkylene group having 1 to 4 carbon atoms.
For example, a methylene group, ethylene group, propylene group, various butylene groups, etc. are mentioned.
The arylene group in the linking group B includes 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, naphthalene-1,4-diyl group, naphthalene-1,5-diyl group, and naphthalene. -2,6-diyl group and the like.
The linking group B may be further substituted, and the substitution is not particularly limited as long as it does not significantly lower the charging characteristics of the polymer compound and the curability of the liquid developer.
The linking group B is not particularly limited as described above, but is more preferably a simple alkylene group such as a methylene group, an ethylene group or a propylene group from the viewpoint of availability of raw materials and ease of production.

In the above formula (1), X ⁻ is a counter anion of a quaternary ammonium moiety, and is a halogen ion or an anion having a COO ⁻ group or SO ₃ ⁻ group in the structure.
Examples of the halogen ion in X ⁻ include fluorine ion, chlorine ion, bromine ion, or iodine ion.
Examples of the anion having a COO ⁻ group in X ⁻ include an acetic acid anion, a propionic acid anion, and a benzoic acid anion.
Examples of the anion having an SO ₃ ^— group in X ⁻ include methanesulfonate anion, trifluoromethanesulfonate anion, benzenesulfonate anion, p-toluenesulfonate anion, and methylsulfate anion.

In the above formula (2), Y ⁻ is a counter anion at the quaternary ammonium moiety, and is covalently bonded to the quaternary ammonium moiety via the divalent linking group B. Y ^- is an anion having a COO ^- group or SO ₃ ^- group in the structure.
Examples of the anion having a COO ⁻ group in Y ⁻ include an acetic acid anion, a propionic acid anion, and a benzoic acid anion.
Examples of the anion containing an SO ₃ ^— group in Y ⁻ include methanesulfonate anion, trifluoromethanesulfonate anion, benzenesulfonate anion, p-toluenesulfonate anion, and methylsulfate anion.

The polymer compound is a copolymer having at least one monomer unit represented by the formula (1) and the formula (2) and a monomer unit represented by the following formula (3). Also good.

[In the above formula (3), R ₆ represents any one of a hydrogen atom and an alkyl group, and R ₇ represents any one of an alkyl group, a carboxylic acid ester group, a carboxylic acid amide group, an alkoxy group and an aryl group. ]

In the above formula (3), the alkyl group for R ₆ is preferably an alkyl group having 1 to 4 carbon atoms. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group.
In the above formula (3), R ₆ can be arbitrarily selected from the substituents listed above and a hydrogen atom, but is preferably a hydrogen atom or a methyl group from the viewpoint of production (polymerizability) of the copolymer. .
In the above formula (3), the alkyl group for R ₇ is preferably an alkyl group having 1 to 30 carbon atoms. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-hexyl group, an n-decyl group, an n-hexadecyl group, an octadecyl group, a docosyl group, and a triacontyl group.
In the above formula (3), examples of the aryl group for R ₇ include aryl groups such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.
In the above formula (3), the carboxylate group in R ₇ is —COOR ₈ (wherein R ₈ is any one of an alkyl group having 1 to 30 carbon atoms, a phenyl group, and a hydroxyalkyl group having 1 to 30 carbon atoms) Represents.). Specifically, methyl ester group, ethyl ester group, n-propyl ester group, isopropyl ester group, n-butyl ester group, tert-butyl ester group, octyl ester group, 2-ethylhexyl ester group, dodecyl ester group, octadecyl Examples include ester groups such as ester groups, docosyl ester groups, triacontyl ester groups, phenyl ester groups, and 2-hydroxyethyl ester groups.
In the above formula (3), as the carboxylic acid amide group in R ₇ , —CO—NR ₉ R ₁₀ (wherein R ₉ and R ₁₀ are each independently a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, and Represents any of phenyl groups). Specifically, N-methylamide group, N, N-dimethylamide group, N, N-diethylamide group, N-isopropylamide group, N-tert-butylamide group, Nn-decylamide group, Nn-hexa Examples include amide groups such as decylamide group, N-octadecylamide group, N-docosylamide group, N-triacontylamide group, and N-phenylamide group.
In the above formula (3), examples of the alkoxy group for R ₇ include an alkoxy group having 1 to 30 carbon atoms and a hydroxyalkoxy group having 1 to 30 carbon atoms. Specifically, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, n-hexyloxy group, cyclohexyloxy group, n-octyloxy group, 2-ethylhexyloxy group, dodecyloxy group And alkoxy groups such as octadecyloxy group, docosyloxy group, triacontyloxy group, and 2-hydroxyethoxy group.

In the above formula (3), the substituent of R ₇ may be further substituted and is not particularly limited as long as it does not significantly lower the charge characteristics of the copolymer and the curability of the liquid developer. In this case, examples of the substituent which may be substituted include an alkoxy group such as a methoxy group and an ethoxy group, an acyl group such as an acetyl group, and a halogen atom such as a fluorine atom and a chlorine atom.
In the above formula (3), R ₆ and R ₇ can be arbitrarily selected from the substituents listed above, but the copolymer is dissolved and dispersed in a low-polar cation polymerizable liquid monomer as a toner charge control agent. In order to improve the solubility in the cationically polymerizable liquid monomer, the dispersibility, and the reverse micelle forming ability, it is preferable to select a substituent having a long-chain alkyl.

The content ratio of at least one of the monomer units represented by the above formulas (1) and (2) is 0.01 mol% or more and 50 mol% with respect to all the monomer units constituting the polymer compound. The content is preferably 1 mol% or less and more preferably 1 mol% or more and 30 mol% or less.
Further, the copolymer composition ratio in the copolymer is not particularly limited, but at least one of the monomer units represented by the above formulas (1) and (2) is a single monomer represented by the above formula (3). The molar ratio to the body unit is preferably 0.01: 99.99 to 50:50, and more preferably 1:99 to 30:70.
When the composition ratio in the polymer compound is in the above range, the function as a toner charge control agent is sufficiently exerted, and excellent solubility or dispersibility in the cationic polymerizable liquid monomer is exhibited.

The weight average molecular weight (Mw) of the polymer compound is not particularly limited, but when used as a toner charge control agent dissolved and dispersed in a cationically polymerizable liquid monomer, the weight average molecular weight (Mw) is 3000 to 300,000. The following degree is preferable, More preferably, it is 3000-150,000.
The content of the polymer compound in the liquid developer is such that the monomer unit represented by the formula (1) or (2) is 10 nmol% or more and 0.1 mmol% or less per unit mass of the toner particles. It is preferable that
By setting the content in the above range, it is possible to obtain a desired charge amount and electrophoretic mobility of toner particles, and it is easy to maintain the electric resistance of the liquid developer, which affects developability and transferability. Does not reach.
In the liquid developer, the content when the polymer compound is dissolved or dispersed in the cationically polymerizable liquid monomer as a toner charge control agent is 0.01 to 100 parts by mass of toner particles (solid content). It may be set to about 10 parts by mass or more.

The method for producing the polymer compound will be described in detail below.
Although the manufacturing method of a high molecular compound will not be specifically limited if the thing of said structure is obtained, For example, it can manufacture by the following methods.
That is, (i) a method for producing a vinyl monomer corresponding to the above formula (1) or (2) and then polymerizing the vinyl monomer, and (ii) a main polymer of the above formula (1) or (2) After synthesizing the polymer compound corresponding to the chain, it can be produced by a method in which the site corresponding to formula (1) or formula (2) is bonded by polymer reaction.
It is preferable to manufacture by the method shown in (i) from the viewpoint of availability of monomers and control of the amount of functional groups. Hereinafter, the method shown in (i) will be described in detail.
The vinyl monomer for introducing the monomer unit represented by the above formula (1) or formula (2) into the polymer compound includes a vinyl ether derivative and an acrylate derivative depending on the structure of the substituent R ₁ and the linking group A. , Methacrylate derivatives, acrylamide derivatives, methacrylamide derivatives, α-olefin derivatives, aromatic vinyl derivatives, etc. can be used, but from the viewpoint of ease of production of monomers, it is preferable to use acrylate derivatives or methacrylate derivatives. .
A commercially available product can be used as the corresponding acrylate derivative or methacrylate derivative.

Examples of the polymerization method of the vinyl monomer include radical polymerization and ionic polymerization, and living polymerization for the purpose of molecular weight distribution control and structure control can also be used. Industrially, it is preferable to use radical polymerization.
The radical polymerization can be performed by using a radical polymerization initiator, irradiation with light such as radiation or laser light, combined use of a photopolymerization initiator and light irradiation, heating, or the like.
The radical polymerization initiator is not particularly limited as long as it can generate radicals and initiate a polymerization reaction, and is selected from compounds that generate radicals by the action of heat, light, radiation, redox reaction, and the like.
Examples thereof include azo compounds, organic peroxides, inorganic peroxides, organometallic compounds, photopolymerization initiators, and the like.
More specifically, azo compounds such as 2,2′-azobisisobutyronitrile (AIBN) and 2,2′-azobis (2,4-dimethylvaleronitrile), benzoyl peroxide (BPO), tert- Organic peroxides such as butyl peroxypivalate and tert-butyl peroxyisopropyl carbonate, inorganic peroxides such as potassium persulfate and ammonium persulfate, hydrogen peroxide-iron (II) salt system, BPO-dimethylaniline system, Examples thereof include redox initiators such as cerium (IV) salt-alcohol. Examples of the photopolymerization initiator include acetophenone series, benzoin ether series, and ketal series. Two or more of these radical polymerization initiators may be used in combination.
The polymerization temperature of the vinyl monomer varies depending on the type of polymerization initiator used, and is not particularly limited. However, polymerization is generally performed at a temperature of −30 ° C. to 150 ° C., and more preferable. The temperature range is 40 ° C to 120 ° C.
The polymerization initiator used at this time is used in an amount of 0.1 to 20 parts by mass with respect to 100 parts by mass of the monomer, so that a polymer compound having a target molecular weight distribution can be obtained. Is preferably adjusted.
As the polymerization method, any method such as solution polymerization, suspension polymerization, emulsion polymerization, dispersion polymerization, precipitation polymerization, and bulk polymerization can be used, and it is not particularly limited.
The obtained polymer compound can be purified as necessary. There is no restriction | limiting in particular as a purification method, Methods, such as reprecipitation, dialysis, and column chromatography, can be used.
The structure of the produced polymer compound can be identified using various instrumental analyses. As an analytical instrument that can be used, a nuclear magnetic resonance apparatus (NMR), gel permeation chromatography (GPC), an inductively coupled plasma optical emission spectrometer (ICP-OES), or the like can be used.
The method for producing the copolymer is not particularly limited as long as the above structure is obtained, and is the same as the polymer compound.
For example, after manufacturing the vinyl monomer corresponding to said Formula (1) or Formula (2) and the vinyl monomer corresponding to said Formula (3), these are superposed | polymerized and the method of manufacturing is mentioned.
At this time, it is also possible to perform polymerization by further adding a vinyl monomer corresponding to the above formula (1) or (2) and a polymerizable monomer other than the vinyl monomer corresponding to the above formula (3).

Hereinafter, each component contained in the liquid developer of the present invention will be described.
The liquid developer includes at least a cationic polymerizable liquid monomer, a polymerization initiator, toner particles insoluble in the cationic polymerizable liquid monomer, and monomer units represented by the above formula (1) or formula (2). It is comprised from the high molecular compound which has at least one.
The toner particles preferably contain a binder resin and a colorant as constituent components.
The polymer compound is a toner charge control agent, and the polymer compound is dissolved or dispersed in a cationically polymerizable liquid monomer.
The liquid developer is obtained by dispersing the toner particles in a cationic polymerizable liquid monomer.

[Cationically polymerizable liquid monomer]
The cationically polymerizable liquid monomer is preferably prepared and used so as to have the same physical property values as those of a normal carrier liquid for a liquid developer. Specifically, the volume resistivity at 25 ° C. is preferably 1 × 10 ⁹ Ω · cm to 1 × 10 ¹⁵ Ω · cm.
When the volume resistivity satisfies the above range, the potential drop of the electrostatic latent image is suppressed, a high optical density can be obtained, and the image blur is further suppressed.
In the present invention, the volume resistivity is measured by an impedance method.
Specifically, the measurement is performed as follows using a dielectric measurement system (125596WB, manufactured by Solartron).
A measuring cell (SC-C1R-C, manufactured by Toyo Technica Co., Ltd.) filled with 1.2 mL of sample is connected to a measuring apparatus and adjusted to 25 ° C. Measurement is performed while changing the frequency in the range of 1 MHz to 0.1 Hz at an applied voltage of 3 V (effective value). The obtained complex impedance is represented by a Nyquist plot, and the values of the resistance component and the capacitor component of the sample are calculated by fitting with an RC parallel equivalent circuit. Further, the volume resistivity is obtained from the cell constant of the measurement cell.

On the other hand, the viscosity of the cationic polymerizable liquid monomer is preferably 0.5 mPa · s or more and less than 100 mPa · s at 25 ° C., more preferably 0.5 mPa · s or more and less than 30 mPa · s.
When the viscosity satisfies the above range, the electrophoretic speed of the toner particles is difficult to decrease, and the printing speed can be maintained.
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.

The cationic polymerizable liquid monomer may be selected from a range that does not dissolve the binder resin. 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.
Examples of the cationic polymerizable liquid monomer include cyclic ether compounds such as vinyl ether compounds, acrylic compounds, epoxy compounds, and oxetane compounds.
Among these, it is preferable to use a vinyl ether compound from the viewpoint of safety to the human body, high sensitivity, high resistance, and low viscosity.
When a vinyl ether compound is used as the cationic polymerizable liquid monomer, other polymerizable liquid monomers may be used in combination so long as the characteristics of the present invention are not impaired.
The vinyl ether compound refers to a compound having a vinyl ether structure (—CH═CH—O—C—).
The vinyl ether structure is preferably represented by R′—CH═CH—O—C— (R ′ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or a methyl group. ).
In the present invention, it is also one of preferred embodiments that the vinyl ether compound is a compound having no hetero atom other than the vinyl ether structure.
Here, the hetero atom means an atom other than a carbon atom and a hydrogen atom.
When a heteroatom is contained in a vinyl ether compound, the electron density is likely to be biased in the molecule due to the difference in electronegativity between the heteroatom and the carbon atom. The resistance tends to decrease because the trajectory tends to be a path of conduction electrons or holes.
Furthermore, it is also one of preferred embodiments that the vinyl ether compound does not have a carbon-carbon double bond other than the vinyl ether structure in the vinyl ether compound. A 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 easily reduce resistance. When a carbon-carbon double bond other than the vinyl ether structure is contained in the vinyl ether compound, the resistance is likely to decrease due to such a mechanism.
Moreover, it is also one of the preferable aspects that a vinyl ether compound is what is represented by a following formula (A).

[In the formula (A), n represents the number of vinyl ether structures in one molecule and is an integer of 1 to 4. R is an n-valent hydrocarbon group. ]
n is preferably an integer of 1 to 3.
R is preferably a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 50 carbon atoms, a saturated or unsaturated alicyclic hydrocarbon group having 5 to 50 carbon atoms, and 6 carbon atoms. A group selected from an aromatic hydrocarbon group having 50 to 50, and the alicyclic hydrocarbon group and the aromatic hydrocarbon group have a saturated or unsaturated aliphatic hydrocarbon group having 1 to 30 carbon atoms. You may do it.
R is more preferably a linear or branched saturated aliphatic hydrocarbon group having 4 to 25 carbon atoms.

Specific examples of the vinyl ether compound [Exemplary compounds B-1 to B-61] are listed below, but the present invention is not limited to these examples.

 

Among these, preferred are dodecyl vinyl ether (B-3), dicyclopentadiene vinyl ether (B-8), cyclohexane-1,4-dimethanol divinyl ether (B-17), triethylene glycol divinyl ether (B- 18), tricyclodecane vinyl ether (B-10), trimethylolpropane trivinyl ether (B-24), 2-ethyl-1,3-hexanediol divinyl ether (B-25), 2,4-diethyl-1, 5-pentanediol divinyl ether (B-26), 2-butyl-2-ethyl-1,3-propanediol divinyl ether (B-27), neopentyl glycol divinyl ether (B-23), pentaerythritol tetravinyl ether ( B-28), 1,2-de Didiol divinyl ether (B-30), 1,2-dodecanediol divinyl ether (B-31), 1,12-dodecanediol divinyl ether (B-32), 1,12-octadecanediol divinyl ether (B-43) ), Phytanetriol trivinyl ether (B-51) and the like.

[Polymerization initiator]
The liquid developer contains a polymerization initiator for polymerizing and curing the cationic polymerizable liquid monomer.
The polymerization initiator is not particularly limited as long as it is a compound capable of generating cationic species capable of initiating cationic polymerization of a cationic polymerizable liquid monomer by reacting with externally input energy such as light and heat. It is preferable to select a photopolymerization initiator from the viewpoint of energy efficiency of the curing step and polymerizability of the cationic polymerizable liquid monomer.
The photopolymerization initiator should be one that significantly lowers the volume resistivity of the liquid developer, significantly inhibits the action of the toner charge control agent of the polymer compound, or significantly increases the viscosity of the liquid developer. Although there is no restriction | limiting in particular, The photoinitiator represented by following formula (4) is preferable.

[In Formula (4), R ₁₁ and R ₁₂ 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 photopolymerization initiator represented by the above formula (4) 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 initiator to decompose and generate sulfonic acid, triggered by absorption of ultraviolet rays by the sensitizer.
Examples of the ring structure formed by combining R ₁₁ and R ₁₂ include a 5-membered ring and a 6-membered ring. Specific examples of the ring structure formed by combining R ₁₁ and R ₁₂ are 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 above formula (4) 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, a hydrogen atom And a cycloalkyl group (RF3) substituted with a fluorine atom, and an aryl group (RF4) wherein 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), 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 thereof 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 above formula (4), from the viewpoint of availability and decomposability of the sulfonic acid ester moiety, 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).

The said polymerization initiator can be used individually by 1 type or in combination of 2 or more types.
The content of the polymerization initiator is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.05 parts by mass with respect to 100 parts by mass of the cationic polymerizable liquid monomer. The amount is 1 part by mass or less, more preferably 0.1 part by mass or more and 0.5 part by mass or less.

Specific examples of the photopolymerization initiator represented by the above formula (4) [Exemplary compounds C-1 to C-27] are listed below, but the present invention is not limited to these examples.

 

 

 

 

Among these, (C-23), (C-24), (C-25), (C-26), and (C-27) are preferable because they can easily obtain high fixability in combination with a sensitizer. .

[Toner particles]
The toner particles preferably contain a binder resin and a colorant as constituent components. Moreover, you may contain additives, such as a charge adjuvant, as needed.
(Binder resin)
As the binder resin, 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, regarding “insoluble in the cationically polymerizable liquid monomer”, an indicator is 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, polyester resins, (meth) acrylic resins, styrene- (meth) acrylic resins, alkyd resins, polyethylene resins, ethylene- (meth) acrylic resins, and rosin-modified resins. Can be mentioned. Moreover, these can be used individually or in combination of 2 or more types as needed.
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.

(Coloring agent)
The colorant is not particularly limited, and all commercially available organic pigments, organic dyes, inorganic pigments, or pigments dispersed in an insoluble resin as a dispersion medium, or the pigment surface A resin-grafted resin can be used.
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 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. and so on.

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, a naphthalenesulfonic acid formalin condensate, a polyoxyethylene alkyl phosphate ester, a pigment derivative, and the like. 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.
The addition amount of these pigment dispersant and pigment dispersion aid is preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the pigment.

[Charge aid]
The toner particles may contain a charge auxiliary agent for the purpose of adjusting the chargeability of the toner particles.
As the charge auxiliary agent, known ones can be used as long as the granulation property of the toner particles and the pigment dispersibility in the toner particles are not significantly lowered and the polymerization property of the cationic polymerizable liquid monomer is not significantly inhibited.
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 and cobalt 2-ethylhexanoate; metal sulfonates such as petroleum metal salts and metal salts of sulfosuccinates; phospholipids such as lecithin; metal complexes of t-butylsalicylate Salicylic acid metal salts such as polyvinylpyrrolidone resin, polyamide resin, sulfonic acid-containing resin, and hydroxybenzoic acid derivatives.
The method for incorporating the charge auxiliary agent in the toner particles is not particularly limited as long as the charge auxiliary agent can be retained in the toner particles.
For example, in the step of granulating toner particles, a method of adding together with a binder resin and a colorant, or a method of granulating the toner particles and then bonding or adsorbing them to the surface of the toner particles by a chemical or physical method. Can be used. For these methods, an optimal method may be selected in accordance with the manufacturing method of the liquid developer.
When the charge auxiliary agent added to the toner particles is detached from the toner particles and dissolved or dispersed in the cation polymerizable liquid monomer, the volume resistivity of the liquid developer is lowered or the toner in the cation polymerizable liquid monomer is reduced. There is a possibility of inhibiting the action of the charge control agent. Therefore, it is preferable to select a structure that lowers the solubility in the cationically polymerizable liquid monomer and improves the affinity of the toner particles to the constituent materials.
In addition, if the charge auxiliary agent desorbs into the cation polymerizable liquid monomer, it can be removed from the cation polymerizable liquid monomer by adsorption with an adsorbent, substitution of the cation polymerizable liquid monomer, or dialysis. It is also possible to use a method for removing the charge auxiliary agent.

[Sensitizer and sensitizer]
The liquid developer may contain a sensitizer as necessary for the purpose of, for example, improving the acid generation efficiency of the photopolymerization initiator and increasing the photosensitive wavelength. The sensitizer is not particularly limited as long as it sensitizes the photopolymerization initiator by an electron transfer mechanism or an energy transfer mechanism.
Specifically, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene, perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone, diethylthioxanthone, Michler ketone, phenothiazine, N-aryloxazolidinone And the like.
The sensitizers can be used alone or in combination of two or more.
The content of the sensitizer is appropriately adjusted according to the purpose, but is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 1 part by mass of the photopolymerization initiator. 1.0 parts by mass or more and 5.0 parts by mass or less.

In addition, the liquid developer may contain a sensitizing aid as necessary for the purpose of improving the electron transfer efficiency or energy transfer efficiency between the sensitizer and the photopolymerization initiator.
Examples of sensitizing aids include naphthalene series such as 1,4-dihydroxynaphthalene, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol And benzene compounds such as 1,4-dihydroxybenzene, 1,4-dimethoxybenzene, 1,4-diethoxybenzene, 1-methoxy-4-phenol, 1-ethoxy-4-phenol, and the like.
The sensitizing aid can be used alone or in combination of two or more.
The content of the sensitizer is appropriately selected according to the purpose, but is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 1 part by mass of the sensitizer. 0.5 parts by mass or more and 5.0 parts by mass or less.

[Cation polymerization inhibitor]
The liquid developer may contain a cationic polymerization inhibitor for the purpose of improving storage stability and adjusting the curing rate.
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-dimethylhencosylamine, 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. Besides these, quaternary ammonium salts and the like can also be used.
The content of the cationic polymerization inhibitor is preferably 1 ppm or more and 5000 ppm or less based on mass in the liquid developer.

[Radical polymerization inhibitor]
The liquid developer may contain a radical polymerization inhibitor.
For example, in a liquid developer containing a vinyl ether compound, the polymerization initiator may be slightly decomposed during storage with time to form a radical compound, which may cause polymerization due to the radical compound. In order to prevent this, it is preferable to contain a radical polymerization inhibitor.
Examples of radical polymerization inhibitors include 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 radicals, 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 polyalkylenes Polya Polycondensates of emissions, 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 liquid developer, phenolic hydroxyl group-containing compounds, N-oxyl free radical compounds, 1,1-diphenyl-2-picrylhydrazyl free radical, phenothiazine, quinones, and hindered amines are preferable. 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 in terms of mass in the liquid developer.

[Other additives]
In addition to the above-described additives, the liquid developer contains various known additives as necessary according to the purpose of improving the compatibility of the recording medium, storage stability, image storage stability, and other performances. It may be used. For example, surfactants, lubricants, fillers, antifoaming agents, ultraviolet absorbers, antioxidants, antifading agents, antifungal agents, rust inhibitors, and the like can be used, and these can be appropriately selected and used. .

A method for producing the 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 toner charge control agent, a cationic polymerizable liquid monomer, and the like can be exemplified.
Details of the coacervation method are described, for example, in 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 the 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.
The toner particle concentration in the 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.

[Characteristics of liquid developer]
The liquid developer may be prepared and used so as to have the following physical property values.
That is, the viscosity of the liquid developer is about 0.5 mPa · s or more and 30 mPa · s or less at 25 ° C. when the toner particle concentration is 2% by mass from the viewpoint that an appropriate electrophoretic mobility of toner particles can be obtained. It is good to.
The volume resistivity of the liquid developer at 25 ° C. is preferably about 1 × 10 ⁹ Ω · cm to 1 × 10 ¹⁵ Ω · cm from the viewpoint of not lowering the potential of the electrostatic latent image.

The measurement method and evaluation method used in the present invention are shown below.
(1) Composition analysis The following method was used to determine the structure of the polymer compound.
Using ECA-400 (400 MHz) manufactured by JEOL Ltd., ¹ H-NMR and ¹³ C-NMR spectra were measured.
Measurement was performed at 25 ° C. in a deuterated solvent containing tetramethylsilane as an internal standard substance. The chemical shift value was shown as a ppm shift value (δ value) with tetramethylsilane as an internal standard substance being zero.

(2) Measurement of molecular weight distribution The molecular weight distribution of the polymer compound was calculated by gel permeation chromatography (GPC) in terms of monodisperse polymethyl methacrylate. The molecular weight was measured by GPC as shown below.
The sample solution was added to the eluent below so that the sample concentration was 1% by mass, and the solution was allowed to stand at room temperature for 24 hours and dissolved, and then filtered through a solvent-resistant membrane filter with a pore diameter of 0.45 μm. And measured under the following conditions.
Equipment: High-speed GPC GPC-104 (made by Showa Denko)
Column: GPC HFIP-603, 604 (made by Showa Denko)
Eluent: hexafluoroisopropanol (HFIP) (containing 10 mmol / L sodium trifluoroacetate)
Flow rate: 0.2 mL / min
Oven temperature: 40 ° C
Sample injection volume: 20 μL
In calculating the molecular weight distribution of the sample, a molecular weight calibration curve prepared with a standard polymethyl methacrylate resin (EasiVial PM Polymer Standard Kit manufactured by Agilent Technologies) was used.

(3) Measurement of Volume Average Particle Size The volume average particle size of toner particles is determined using a dynamic light scattering (DLS) particle size distribution measuring device (trade name: Nanotrack 150, manufactured by Nikkiso Co., Ltd.). Measurements were made in a polymerizable liquid monomer.

(4) Evaluation of electrophoretic mobility The electrophoretic mobility of the produced liquid developer was measured as follows.
A sample diluted with a cationically polymerizable liquid monomer so that the toner particle concentration was 1% by mass was held by a capillary force between parallel plate electrodes, which were opposed to each other with a metal electrode having a thickness of 300 μm and a width of 20 mm separated by 100 μm.
The state of electrophoresis when a potential difference of 100 V was applied between parallel plate electrodes (electric field intensity 1 × 10 ⁶ V / m) was photographed with a high-speed camera (FASTCAM SA-1 manufactured by Photoron) connected to an optical microscope. .
The obtained image was taken into image processing software ImageJ (developer: Wayne Rasband (NIH)), and the average electrophoretic mobility of the particles was calculated by a particle image velocimetry (PIV method). The migration polarity of the particles was negative when migrating to the positive electrode and positive when migrating to the negative electrode.
The electrophoretic mobility was evaluated according to the following criteria.
A: Average migration mobility is 1 × 10 ⁻⁹ m ² / V · s or more B: Average migration mobility is 7 × 10 ⁻¹⁰ m ² / V · s or more, 1 × 10 ⁻⁹ m ² / V · s Less than C: Average migration mobility is 3 × 10 ⁻¹⁰ m ² / V · s or more, less than 7 × 10 ⁻¹⁰ m ² / V · s D: Average migration mobility is 1 × 10 ⁻¹⁰ m ² / V · s s or more and less than 3 × 10 ⁻¹⁰ m ² / V · s E: the average migration mobility is less than 1 × 10 ⁻¹⁰ m ² / V · s or does not show clear migration, and the average migration mobility is 7 × 10 ^{If it was −10} m ² / V · s or higher (A or B rank), it was judged that the electrophoretic mobility and the charge amount were high and good.

(5) Evaluation of curability In an environment of room temperature of 25 ° C. and humidity of 50% RH, a liquid developer was dropped on a polyethylene terephthalate film (manufactured by Toray, Lumirror: 75E20, thickness 75 μm), and a wire bar (No. 6). ) Bar coating using [Supplier: Matsuo Sangyo Co., Ltd.] (formed film thickness 13.7 μm), irradiating light with a wavelength of 365 nm with a high-pressure mercury lamp with a lamp output of 120 mW / cm ² , and cured film Formed. The irradiation light quantity when the surface was completely cured without tack (adhesiveness) was measured and evaluated according to the following criteria.
A: 200mJ / cm ² less B: 200mJ / cm ² or more, 400 mJ / cm ² less than C: 400mJ / cm ² or more, 700 mJ / cm ² less than D: 700mJ / cm ² or more, 1000 mJ / cm ² less than E: 1000 mJ / cm ² or more, or the irradiation light quantity not cured is less than 400 mJ / cm ² (a or B rank), high curability was judged to be good.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. All “parts” described in the examples represent parts by mass.
(Production of polymer compound 1)
In a reaction vessel equipped with a condenser, a stirrer, a thermometer and a nitrogen inlet tube, 15.8 parts of [2- (methacryloyloxy) ethyl] trimethylammonium chloride (80% aqueous solution), 82.1 parts of octadecyl methacrylate, azobis 4.1 parts of isobutyronitrile and 900 parts of n-butanol were charged, and nitrogen bubbling was performed for 30 minutes. The resulting reaction mixture was heated at 65 ° C. for 8 hours under a nitrogen atmosphere to complete the polymerization reaction. After cooling the reaction solution to room temperature, the solvent was distilled off under reduced pressure. The obtained residue was dissolved in chloroform and purified by dialysis using a dialysis membrane (Spectra / Por7 MWCO 1 kDa manufactured by Spectrum Laboratories). After the solvent was distilled off under reduced pressure, polymer compound 1 was obtained by drying under reduced pressure at 50 ° C. and 0.1 kPa or less.
When the obtained polymer compound 1 was analyzed by the above analytical method, the weight average molecular weight (Mw) was 23500, and the monomer unit (unit 1) represented by the formula (1) was all monomers. It was confirmed that the unit contained 23 mol%.

(Production of polymer compound 2)
In the same manner as in the production of the polymer compound 1, except that 17.1-part of [2- (methacryloyloxy) ethyl] trimethylammonium methylsulfate is used instead of [2- (methacryloyloxy) ethyl] trimethylammonium chloride. Molecular compound 2 was produced.

(Production of polymer compound 3)
Other than using 13.1 parts of N-carboxymethyl-N, N-dimethyl-N- [2- (methacryloyloxy)] ethylammonium betaine instead of [2- (methacryloyloxy) ethyl] trimethylammonium chloride Polymer compound 3 was produced in the same manner as in the production of molecular compound 1.

(Production of polymer compound 4)
Use 17.0 parts of N, N-dimethyl-N- [2- (methacryloyloxy) ethyl] -N- (3-sulfopropyl) ammonium betaine instead of [2- (methacryloyloxy) ethyl] trimethylammonium chloride. Except for the above, polymer compound 4 was produced in the same manner as in the production of polymer compound 1.

(Production of polymer compound 5)
A polymer compound 5 was produced in the same manner as the polymer compound 1 except that 48.1 parts of octyl methacrylate was used instead of octadecyl methacrylate.

(Production of polymer compound 6)
In place of [2- (methacryloyloxy) ethyl] trimethylammonium chloride, 12.2 parts of N- [2- (acryloyloxy)] ethyl-N-carboxymethyl-N, N-dimethylammonium betaine are used instead of octadecyl methacrylate. The polymer compound 6 was produced in the same manner as the polymer compound 1 except that 78.7 parts of octadecyl acrylate was used.

(Production of polymer compound 7)
A polymer compound 7 was produced in the same manner as the polymer compound 1 except that 12.8 parts of (vinylbenzyl) trimethylammonium chloride was used instead of [2- (methacryloyloxy) ethyl] trimethylammonium chloride.

(Production of polymer compound 8)
In place of [2- (methacryloyloxy) ethyl] trimethylammonium chloride and octadecyl methacrylate, 109.8 parts of N, N-dimethyl-N-dodecyl-N- [2- (methacryloyloxy) ethyl] ammonium chloride were added. A polymer compound 8 was produced in the same manner as in the production of the polymer compound 1 except that it was used.

Table 1 shows the composition ratios and weight average molecular weights (Mw) of the polymer compounds 1 to 8 produced as described above. In Table 1, “a” is the bonding site with the carbon atom to which R _{1 in} Formula (1) or Formula (2) is bonded, “b” is the binding site with the quaternary ammonium moiety, and “c”. Represents the bonding site to the carbon atom to which R ₆ in Formula (3) is bonded.

 

<Example 1>
[Manufacture of binder resin]
In a reaction vessel equipped with a reflux condenser, water / alcohol separator, nitrogen gas inlet tube, thermometer and stirrer, 1500 parts of bisphenol A ethylene oxide adduct (Sigma Aldrich) and 700 parts of terephthalic acid (Sigma Aldrich) was added, nitrogen gas was introduced while stirring, and dehydration / dealcoholization polycondensation reaction was performed at a temperature of 200 to 240 ° C.
After 1 hour, the temperature of the reaction system was lowered to 100 ° C. or less to stop polycondensation. The obtained polyester resin had a weight average molecular weight (Mw) of 9000, a number average molecular weight (Mn) of 2100, a glass transition temperature (Tg) of 68 ° C., and an acid value of 12.0 mgKOH / g.

[Production of toner particle dispersion]
In a reaction vessel equipped with a stirrer and a thermometer, 25 parts of the polyester resin and 75 parts of dodecyl vinyl ether (Exemplary Compound B-3) are charged and stirred at 200 rpm for 1 hour up to 130 ° C. in an oil bath. The temperature rose. 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.
60 parts of the above binder resin dispersion, 5 parts of Pigment Blue 15: 3, and 35 parts of dodecyl vinyl ether are filled together with zirconia beads having a diameter of 0.5 mm in a planetary bead mill (Fritsch Classic Line P-6) at room temperature. Was pulverized at 200 rpm for 4 hours to obtain a toner particle dispersion (solid content 20 mass%). The toner particles contained in the obtained toner particle dispersion had a volume average particle size of 0.91 μm.

[Preparation of toner charge control agent solution]
In a reaction vessel equipped with a stirrer and a thermometer, 6.2 parts of the polymer compound 1 and 68.2 parts of tetrahydrofuran (THF) were charged, and the temperature was raised to 60 ° C. to dissolve the polymer compound 1. . After adding 71.3 parts of dodecyl vinyl ether, THF was distilled off under reduced pressure at 50 ° C. and 4 kPa to obtain a transparent toner charge control agent solution.

[Preparation of liquid developer]
To 10.0 parts of the above toner particle dispersion, 0.125 parts of a toner charge control agent solution, 16.10 parts of dodecyl vinyl ether, 2-butyl-2-ethyl-1,3-propanediol divinyl ether (Exemplary Compound B- 27) After mixing 72.63 parts, 0.29 part of N-hydroxynaphthalimide nonafluorobutanesulfonate (Exemplary Compound C-26) as a photopolymerization initiator and 0.48 of 2,4-diethylthioxanthone as a sensitizer The liquid developer of Example 1 was produced by mixing and dissolving 0.48 parts of 1,4-diethoxynaphthalene as a sensitizing aid.

<Examples 2 to 8>
Liquid developers of Examples 2 to 8 were produced in the same manner as in Example 1 except that the polymer compounds 2 to 8 were used in place of the polymer compound 1, respectively.

<Example 9>
In the [preparing liquid developer] step of Example 1, 79.04 parts of dodecyl vinyl ether was used, and cyclohexane-1,4-dimethanol was used instead of 2-butyl-2-ethyl-1,3-propanediol divinyl ether. A liquid developer of Example 9 was produced in the same manner as in Example 1 except that 9.68 parts of divinyl ether (Exemplary Compound B-17) was used.

<Example 10>
Example 1 except that N-hydroxyphthalimidononafluorobutanesulfonate (Exemplary Compound C-11) is used instead of N-hydroxynaphthalimidenonafluorobutanesulfonate in the [Preparation of Liquid Developer] step of Example 1. In the same manner as described above, the liquid developer of Example 10 was produced.

<Example 11>
In the [Production of Toner Particle Dispersion] step of Example 1, in the same manner as in Example 1 except that Nucrel N1525 (ethylene-methacrylic acid resin, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used instead of the polyester resin. Thus, a liquid developer of Example 11 was produced.

<Example 12>
In the [Production of toner particle dispersion] step of Example 1, 1,12-octadecanediol divinyl ether (Exemplary Compound B-43) was used instead of dodecyl vinyl ether, and in the [Preparation of liquid developer] step, dodecyl vinyl ether was used. And the liquid of Example 12 in the same manner as in Example 1 except that 88.73 parts of 1,12-octadecanediol divinyl ether was used instead of 2-butyl-2-ethyl-1,3-propanediol divinyl ether. A developer was produced.

<Example 13>
A liquid developer of Example 13 was produced in the same manner as in Example 12 except that the polymer compound 3 was used instead of the polymer compound 1.
The above dodecyl vinyl ether (Exemplary Compound B-3), 2-butyl-2-ethyl-1,3-propanediol divinyl ether (Exemplary Compound B-27), cyclohexane-1,4-dimethanol divinyl ether (Exemplary Compound) The volume resistivity of B-17) and 1,12-octadecanediol divinyl ether (Exemplary Compound B-43) at 25 ° C. was 2.7 × 10 ¹² Ω · cm and 9.4 × 10 ¹² Ω, respectively. · Cm, 1.3 × 10 ¹⁰ Ω · cm and 8.4 × 10 ¹² Ω · cm.

<Comparative Example 1>
A liquid developer of Comparative Example 1 was produced in the same manner as in Example 1 except that the polymer compound 1 was not used as the toner charge control agent.

<Comparative example 2>
A liquid developer of Comparative Example 2 was produced in the same manner as in Example 1 above, except that lecithin (derived from soybeans manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of the polymer compound 1 as the toner charge control agent.

<Comparative Example 3>
A liquid developer of Comparative Example 3 was produced in the same manner as in Example 1 above, except that barium sulfonate (Molesco Amber SB-50N manufactured by Moresco) was used instead of the polymer compound 1 as the toner charge control agent.

<Comparative example 4>
The liquid developer of Comparative Example 4 was used in the same manner as in Example 1 except that sodium di (2-ethylhexyl) sulfosuccinate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of the polymer compound 1 as the toner charge control agent. Manufactured.

Table 2 below shows the electrophoretic mobility and curability evaluation results of the liquid developer produced above.

As shown in Table 2, it can be seen that when the polymer compounds 1 to 8 are added to the liquid developer as a toner charge control agent, a curable liquid developer having high electrophoretic mobility and curability is obtained.

According to the present invention, it is possible to provide a curable liquid developer that has high curability and can cope with an increase in the process speed of the image forming apparatus.

Claims (8)

1. A curable liquid developer comprising a cationic polymerizable liquid monomer, a polymerization initiator, and toner particles insoluble in the cationic polymerizable liquid monomer,
   A curable liquid developer comprising a polymer compound having at least one of monomer units represented by the following formulas (1) and (2).
   

   

   
   [In the formulas (1) and (2), R ₁ to R ₄ each independently represents a hydrogen atom or an alkyl group, A and B represent a divalent linking group, and X ⁻ represents a halogen atom. An ion or an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure is represented, and Y ⁻ represents an anion having a COO ⁻ group or an SO ₃ ⁻ group in the structure. ]
2. The polymer compound is a copolymer having at least one monomer unit represented by the formula (1) and the formula (2) and a monomer unit represented by the following formula (3). The curable liquid developer according to claim 1.
   

   

   
   [In the formula (3), R ₆ represents any one of a hydrogen atom and an alkyl group, and R ₇ represents any one of an alkyl group, a carboxylic acid ester group, a carboxylic acid amide group, an alkoxy group and an aryl group. ]
3. A represents an alkylene group, an arylene group, an aralkylene group, a-COOR ₅ -b, a-CONHR ₅ -b, and a-OR ₅ -b (where a represents a bonding site with the carbon atom to which R ₁ is bonded). Or b represents a bonding site with a quaternary ammonium moiety, R ₅ represents an alkylene group or an arylene group, and B represents either an alkylene group or an arylene group. The curable liquid developer described in 1.
4. The content ratio of at least one of the monomer units represented by the formulas (1) and (2) is 0.01 mol% or more and 50 mol% with respect to all the monomer units constituting the polymer compound. The curable liquid developer according to any one of claims 1 to 3, which is as follows.
5. The curable liquid developer according to any one of claims 1 to 4, wherein the cationically polymerizable liquid monomer contains a vinyl ether compound.
6. The curable liquid developer according to any one of claims 1 to 5, wherein the polymerization initiator contains a photopolymerization initiator represented by the following formula (4).
   

   

   
   [In Formula (4), R ₁₁ and R ₁₂ 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. ]
7. The curable liquid developer according to any one of claims 1 to 6, wherein the toner particles contain a polyester resin.
8. The cationic polymerizable liquid monomer contains a vinyl ether compound;
   The curable liquid developer according to any one of claims 1 to 7, wherein the vinyl ether compound has a volume resistivity at 25 ° C of 1 × 10 ⁹ Ω · cm to 1 × 10 ¹⁵ Ω · cm. .