JP6666038B2 - Liquid developer - Google Patents

Description

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

In the electrophotographic method, the surface of an image carrier such as a photoreceptor is uniformly charged (charging step), and an electrostatic latent image is formed on the surface of the image carrier by exposure (exposure step). The electrostatic latent image is developed with a developer composed of colored particles (development step), the developer image is transferred to a recording medium such as paper or a plastic film (transfer step), and the transferred developer image is fixed on the recording medium. (Fixing step) to obtain a printed material.
In this case, the developer is a dry developer in which colored particles composed of a material including a colorant such as a pigment and a binder resin are used in a dry state, and a liquid in which the colored particles are dispersed in an electrically insulating liquid as a carrier liquid. It is roughly classified into a developer.
2. Description of the Related Art In recent years, needs for colorization and high-speed printing of image forming apparatuses such as a copying machine, a facsimile, and a printer using an electrophotographic method have been increasing. In color printing, a high-resolution and high-quality image is required. Therefore, a developer that can form a high-resolution and high-quality image and that can support high-speed printing is required.
A liquid developer is known as an advantageous developer with respect to reproducibility of a color image. Since the liquid developer hardly causes the aggregation of the colored particles in the developer, fine toner particles can be used. Therefore, the liquid developer easily obtains characteristics excellent in reproducibility of a fine line image and gradation reproducibility. The development of high-quality, high-speed digital printing apparatuses utilizing electrophotographic technology using a liquid developer, taking advantage of these excellent features, is becoming active. Under such circumstances, development of a liquid developer having better characteristics is required.
Various charge control agents (Charge Control Agents) have been studied to charge toner particles of a liquid developer and develop and transfer the developer by electrophoresis.
For example, Patent Document 1 proposes that a low-molecular compound such as lecithin effectively functions as a toner charge control agent (toner charge control agent) that negatively charges a toner.
On the other hand, Patent Document 2 proposes that a polymer compound containing a quaternary ammonium salt is a useful negatively chargeable toner charge control agent.
Further, in Patent Document 3, a charge auxiliary agent (Charge) for making a toner positively chargeable by containing a similar polymer compound containing a quaternary ammonium salt in toner particles.
Adjuvant).

Japanese Patent No. 3267716 JP-A-7-319223 JP-A-7-261467

However, in recent years, since the process speed of an image forming apparatus has been increased, the toner charge control agents proposed so far are insufficient, and a toner charge control agent and a charge assisting agent for further improving the electrophoretic mobility of toner particles are not sufficient. There is a need for the development of agents.
Therefore, the present invention provides a toner charge control agent and a charge auxiliary agent that further improve the charge amount and electrophoretic mobility of toner particles, and provide a liquid developer that can cope with an increase in the process speed of an image forming apparatus. Things.

［前記式（１）中、Ｒ_１〜Ｒ_４はそれぞれ独立して、水素原子及びアルキル基のいずれかを表し、Ａは単結合、カルボニル基、アルキレン基、アリーレン基及び−ＣＯＯＲ_７−（ただし、−ＣＯＯＲ_７−中のカルボニル基はＲ_１が結合した炭素原子に結合し、Ｒ_７は炭素数１以上４以下のアルキレンを表す）のいずれかを表し、Ｂはアルキレン基及びアリーレン基のいずれかを表す。］ The present invention is a liquid developer containing toner particles and a carrier liquid,
A liquid developer comprising a polymer compound having a structural unit represented by the following formula (1) in either the toner particles or the carrier liquid.

[In the formula (1), R _{1 to} R ₄ each independently represent any of a hydrogen atom and an alkyl group, and A represents a single bond, a carbonyl group, an alkylene group, an arylene group, and —COOR ₇ — , -COOR _7- is bonded to the carbon atom to which R ₁ is bonded, and R ₇ represents alkylene having 1 to 4 carbon atoms), and B represents any of an alkylene group and an arylene group. Represents. ]

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

Hereinafter, the present invention will be described in detail.
The liquid developer of the present invention is a liquid developer containing toner particles and a carrier liquid,
A polymer compound having a structural unit represented by the following formula (1) is contained in either the toner particles or the carrier liquid.

［上記式（１）中、Ｒ_１〜Ｒ_４はそれぞれ独立して、水素原子及びアルキル基のいずれかを表し、Ａは単結合、カルボニル基、アルキレン基、アリーレン基及び−ＣＯＯＲ_７−（ただし、−ＣＯＯＲ_７−中のカルボニル基はＲ_１が結合した炭素原子に結合し、Ｒ_７は炭素数１以上４以下のアルキレンを表す）のいずれかを表し、Ｂはアルキレン基及びアリーレン基のいずれかを表す。］

[In the above formula (1), R _{1 to} R ₄ each independently represent any of a hydrogen atom and an alkyl group, and A represents a single bond, a carbonyl group, an alkylene group, an arylene group, and —COOR ₇ — ( , -COOR _7- is bonded to the carbon atom to which R ₁ is bonded, and R ₇ represents alkylene having 1 to 4 carbon atoms), and B represents any of an alkylene group and an arylene group. Represents. ]

Hereinafter, the structural unit represented by the formula (1) and the polymer compound having the structural unit will be described in detail.
The structural unit represented by the formula (1) has excellent positive charge acceptability.
Therefore, by dissolving or dispersing the polymer compound having the structural unit in the carrier liquid, the polymer compound having the structural unit is adsorbed on the toner particles and receives a positive charge from the toner particles. As a result, the toner particles are negatively charged. That is, the high molecular compound having the structural unit functions as a toner charge control agent for negatively charging the toner particles.
On the other hand, when the toner particles contain a polymer compound having the structural unit, the toner particles receive a positive charge and act as a charge auxiliary for positively charging the toner particles.

In the above formula (1), the alkyl group for R ₁ is preferably an alkyl group having 1 to 4 carbon atoms. For example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and the like can be mentioned.
R ₁ in the above formula (1) can be arbitrarily selected from the above-listed substituents and hydrogen atoms, and is preferably a hydrogen atom or a methyl group from the viewpoint of production (polymerizability) of a polymer compound. .

In the above formula (1), the alkyl group for R _{2 to} R ₄ is preferably an alkyl group having 1 to 18 carbon atoms. Examples 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 formula (1), A is a linking group which binds the polymer backbone and the phosphate ester moiety, a carbonyl group, an alkylene group, an arylene group, and -COOR ₇ - (However, -COOR ₇ - carbonyl group of medium Is bonded to the carbon atom to which R ₁ is bonded, and R ₇ represents an alkylene having 1 to 4 carbon atoms. Further, it may be directly connected to the polymer main chain by a single bond.
The alkylene group in the linking group A may be linear or branched, and is preferably an alkylene group having 1 to 4 carbon atoms.
For example, a methylene group, an ethylene group, a propylene group, various butylene groups and the like can be mentioned.
Examples of the arylene group in the linking group A include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, And a naphthalene-2,6-diyl group.
As —COOR ₇ — in the linking group A, the carbonyl group in —COOR ₇ — is bonded to the carbon atom to which R ₁ is bonded, and R ₇ is alkylene having 1 to 4 carbon atoms. The alkylene may be linear or branched.
These linking groups 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.
While the linking group A is not limited particularly as described above, the raw material availability and ease of manufacture of the viewpoint from the carbonyl group, or, -COOR 7 - _(However, -COOR 7 _- carbonyl group of medium is R ₁ is bonded to the bonded carbon atom, and R ₇ represents alkylene having 1 to 4 carbon atoms).

In the above formula (1), B is a linking group connecting the phosphate moiety and the quaternary ammonium moiety, and represents one of an alkylene group and an arylene group.
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, an ethylene group, a propylene group, various butylene groups and the like can be mentioned.
Examples of the arylene group in the linking group B include a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a naphthalene-1,4-diyl group, a naphthalene-1,5-diyl group, And a naphthalene-2,6-diyl group.
These linking groups 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.
The linking group B is not particularly limited as described above, but is preferably a simple alkylene group such as a methylene group and an ethylene group from the viewpoint of availability of raw materials and ease of production.

  In the present invention, either the toner particles or the carrier liquid may contain a structural unit represented by the above formula (1) and a copolymer having a structural unit represented by the following formula (2). preferable.

［上記式（２）中、Ｒ_５は水素原子及びアルキル基のいずれかを表し、Ｒ_６はアルキル基、カルボン酸エステル基、カルボン酸アミド基、アルコキシ基及びアリール基のいずれかを表す。］

[In the above formula (2), R ₅ represents any one of a hydrogen atom and an alkyl group, and R ₆ represents any one of an alkyl group, a carboxylic ester group, a carboxylic amide group, an alkoxy group, and an aryl group. ]

In the above formula (2), the alkyl group for R ₅ is preferably an alkyl group having 1 to 4 carbon atoms. For example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and the like can be mentioned.
In the above formula (2), R ₅ can be arbitrarily selected from the above-listed substituents and hydrogen atoms, but is preferably a hydrogen atom and a methyl group from the viewpoint of production (polymerizability) of the copolymer. .
In the above formula (2), the alkyl group for R ₆ is preferably an alkyl group having 1 to 30 carbon atoms. Examples 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 formula (2), examples of the aryl group for R ₆ include aryl groups such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.
In the above formula (2), the carboxylic acid ester group for R ₆ is -COOR ₈ (where 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 (2), the carboxylic acid amide group for R ₆ includes —CO—NR ₉ R ₁₀ (where R ₉ and R ₁₀ are each independently hydrogen, an alkyl group having 1 to 30 carbon atoms and phenyl). Represents any of the 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 Amide groups such as a decylamide group, an N-octadecylamide group, an N-docosylamide group, an N-triacontylamide group, and an N-phenylamide group.
In the above formula (2), examples of the alkoxyl group for R ₆ include an alkoxy group having 1 to 30 carbon atoms and a hydroxyalkoxy group having 1 to 30 carbon atoms. Specifically, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, n-hexyloxy, cyclohexyloxy, n-octyloxy, 2-ethylhexyloxy, dodecyloxy Octadecyloxy group, docosyloxy group, triacontyloxy group, and alkoxy group such as 2-hydroxyethoxy group.

In the above formula (2), the substituent of R ₆ may be further substituted, and is not particularly limited as long as it does not significantly lower the charging characteristics of the copolymer. In this case, examples of the substituent that may be substituted include an alkoxy group such as a methoxy group and an ethoxy group, an amino group such as an N-methylamino group and an N, N-dimethylamino group, an acyl group such as an acetyl group, and a fluorine atom. And a halogen atom such as a chlorine atom.
In the above formula (2), R ₅ and R ₆ can be arbitrarily selected from the substituents enumerated above, and an appropriate substituent may be selected depending on the use in which the copolymer is used.
For example, when used by dissolving and dispersing in a low-polarity carrier liquid as a toner charge control agent, it has a long-chain alkyl to improve solubility and dispersibility in the carrier liquid and reverse micelle forming ability. It is preferable to select such substituents.
On the other hand, when it is contained in the toner particles as a charge auxiliary, it is preferable to select a substituent that reduces the solubility in the carrier liquid and improves the affinity for the binder resin.

In the present invention, the copolymer composition ratio in the copolymer is not particularly limited, but the molar ratio of the structural unit represented by the formula (1) to the structural unit represented by the formula (2) is 0.1. The ratio is preferably from 01: 99.99 to 50:50, more preferably from 1:99 to 30:70.
When the copolymerization composition ratio is in the above range, the function as a charge control agent or a charge auxiliary agent is sufficiently exhibited, the solubility and dispersibility in the carrier liquid are excellent, and the affinity for the binder resin is also obtained. Also excellent.

The weight average molecular weight (Mw) of the polymer compound or copolymer is not particularly limited, but a molecular weight according to the intended use may be appropriately selected.
For example, when the toner charge control agent is used after being dissolved and dispersed in a carrier liquid, the weight average molecular weight (Mw) is preferably about 3000 to 300,000, more preferably 3000 to 150,000.
When Mw is 300,000 or more, the solubility and dispersibility in the carrier liquid are reduced, and the function as a toner charge control agent tends to be reduced.
Further, when it is contained in the toner particles as a charge auxiliary, the Mw is preferably from 3,000 to 300,000, more preferably from 3,000 to 150,000.
When Mw is less than 3,000, elution from the toner particles into the carrier liquid increases, and the function as a charge auxiliary agent tends to decrease. On the other hand, when Mw exceeds 300,000, the compatibility and dispersibility in the binder resin tend to decrease.

In the liquid developer of the present invention, the content of the high molecular compound or the copolymer is such that the structural unit represented by the above formula (1) is from 10 nmol% to 0.1 mmol% per unit mass of the toner particles. Is preferred.
By adjusting the content to the above range, a desired charge amount and electrophoretic mobility of the toner particles can be obtained, and the electric resistance of the liquid developer can be easily maintained, which affects the developability and transferability. Has no effect.
On the other hand, in the liquid developer of the present invention, the content of the polymer compound or copolymer when dissolved or dispersed in the carrier liquid is 0.01 mass with respect to 100 mass parts of the toner particles (solid content). And not more than about 10 parts by mass.
When the toner particles contain the above-mentioned polymer compound or copolymer, the content is preferably about 0.01% by mass to 10% by mass with respect to the toner particles (solid content).

Hereinafter, a method for producing the polymer compound and the copolymer (hereinafter, also collectively referred to as a polymer compound) will be described in detail.
The method for producing the polymer compound is not particularly limited as long as the compound having the above structure is obtained. For example, the polymer compound can be produced by the following method.
That is, (i) a method of producing a vinyl monomer corresponding to the above formula (1) and then polymerizing the same, and (ii) synthesizing a polymer compound corresponding to the polymer main chain of the above formula (1) And by a method of bonding the zwitterionic sites of formula (1) by a polymer reaction.
It is preferable to produce by the method shown in (i) from the viewpoint of the availability of the monomer and the control of the amount of the functional group. Hereinafter, the method shown in (i) will be described in detail.
The vinyl monomer for introducing the structural unit represented by the above formula (1) into the polymer compound includes, depending on the structure of the substituent R ₁ and the linking group A, a vinyl ether derivative, an acrylate derivative, a methacrylate derivative, α- Although an olefin derivative, an aromatic vinyl derivative, or the like can be used, it is preferable to use an acrylate derivative or a methacrylate derivative from the viewpoint of easy production of the monomer.
The corresponding acrylate derivative or methacrylate derivative can be produced by the method described in the following literature.
K. Ishihara and 2 others, "Polymer Journal", (Japan), The Society of Polymer Science, 1990, Vol. 22, p. 355-360.
Examples of the method for polymerizing 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, radical polymerization is preferably used.
The radical polymerization can be performed by using a radical polymerization initiator, irradiating light such as radiation or laser light, using a combination of the photopolymerization initiator and light irradiation, and heating.
The radical polymerization initiator may be any compound capable of generating a radical and initiating a polymerization reaction, and is selected from compounds that generate a radical by the action of heat, light, radiation, an oxidation-reduction reaction, or the like.
For example, an azo compound, an organic peroxide, an inorganic peroxide, an organometallic compound, a photopolymerization initiator and the like can be mentioned.
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 butylperoxypivalate and tert-butylperoxyisopropyl carbonate, inorganic peroxides such as potassium persulfate and ammonium persulfate, hydrogen peroxide-iron (II) salt system, BPO-dimethylaniline system, A redox initiator such as a cerium (IV) salt-alcohol system may be used. Examples of the photopolymerization initiator include acetophenone type, benzoin ether type, and ketal type. Two or more of these radical polymerization initiators may be used in combination.
The preferred polymerization temperature of the vinyl monomer varies depending on the type of the polymerization initiator used, and is not particularly limited. However, the polymerization is generally performed at a temperature of -30 ° C to 150 ° C, and is more preferably performed. The temperature range is between 40C and 120C.
The amount of the polymerization initiator used at this time is 0.1 to 20 parts by mass with respect to 100 parts by mass of the monomer, and is used so as to obtain a polymer compound having a target molecular weight distribution. 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 is not particularly limited.
The obtained polymer compound can be purified if necessary. The purification method is not particularly limited, and methods such as reprecipitation, dialysis, and column chromatography can be used.
The structure of the produced polymer compound can be identified using various types of instrumental analysis. As an analytical instrument that can be used, a nuclear magnetic resonance apparatus (NMR), a gel permeation chromatography (GPC), an inductively coupled plasma emission analyzer (ICP-OES), or the like can be used.
The method for producing the above copolymer is not particularly limited as long as it has the above structure, and is the same as the above polymer compound.
For example, there is a method of producing a vinyl monomer corresponding to the above formula (1) and a vinyl monomer corresponding to the above formula (2), and then polymerizing them.
At this time, it is also possible to polymerize by further adding a polymerizable monomer other than the vinyl monomer corresponding to the above formula (1) and the vinyl monomer corresponding to the above formula (2).

Hereinafter, each component contained in the liquid developer of the present invention will be described.
The liquid developer of the present invention comprises at least a carrier liquid, toner particles insoluble in the carrier liquid, and a polymer compound containing a structural unit represented by the above formula (1).
Further, the toner particles contain a binder resin and a colorant as constituent components.
When the polymer compound is used as a toner charge control agent, the polymer compound is dissolved or dispersed in the carrier liquid. On the other hand, when the polymer compound is used as a charge auxiliary, the polymer compound is contained in the toner particles.
The liquid developer has the toner particles dispersed in the carrier liquid.

[Carrier liquid]
The carrier liquid is not particularly limited as long as it has a high volume resistivity, has electrical insulation properties, and has a low viscosity at around room temperature.
Specifically, hydrocarbon solvents such as hexane, heptane, and octane; and liquid paraffinic solvents such as Isopar G, Isopar E, Isopar L (manufactured by ExxonMobil), and Moresco White P-40 (manufactured by MORESCO) Examples thereof include a solvent and a silicone compound.
The volume resistivity of the carrier liquid is preferably 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less, and more preferably 1 × 10 ¹⁰ Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less. More preferred.
When the volume resistivity is less than 1 × 10 ⁹ Ω · cm, the potential of the electrostatic latent image tends to decrease, and it tends to be difficult to obtain a high optical density, and the image tends to be blurred.
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 measurement cell (SC-C1R-C, manufactured by Toyo Corp.) filled with 1.2 mL of the sample is connected to the measurement device and adjusted to 25 ° C. The measurement is performed at an applied voltage of 3 V (effective value) while changing the frequency in the range of 1 MHz to 0.1 Hz. 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 a RC parallel equivalent circuit. Further, the volume resistivity is determined from the cell constant of the measurement cell.
On the other hand, the viscosity of the carrier liquid at 25 ° C. is preferably 0.5 mPa · s or more and less than 200 mPa · s, and more preferably 0.5 mPa · s or more and less than 100 mPa · s. If the viscosity is too high, the electrophoretic speed of the toner particles tends to decrease, and the printing speed tends to decrease.
In the present invention, the viscosity is measured by a rotary rheometer method.
Specifically, the measurement is performed as follows using a viscoelasticity measuring device (Physica MCR300, manufactured by Anton Paar).
A measuring device equipped with a cone plate type measuring jig (75 mm diameter, 1 °) is filled with about 2 mL of the sample 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 defined as the viscosity.

In order to make the liquid developer of the present invention an ultraviolet curable type, a polymerizable monomer may be used for the carrier liquid.
The polymerizable monomer that can be used is not particularly limited as long as the characteristics of the carrier liquid are satisfied.
Examples of the polymerizable monomer include a vinyl ether compound, an epoxy compound, an acrylic compound, and an oxetane compound.
Among them, vinyl ether compounds are preferred from the viewpoints of safety to human body, high resistance, and low viscosity.
The vinyl ether compound refers to a compound having a vinyl ether structure (-CH = CH-OC-).
The vinyl ether structure is preferably represented by R-CH = CH-OC- (R is hydrogen or alkyl having 1 to 3 carbon atoms, preferably hydrogen or methyl).
In a preferred embodiment of the present invention, the vinyl ether compound is a compound having no hetero atom other than the above vinyl ether structure.
Here, the hetero atom means an atom other than a carbon atom and a hydrogen atom.
When a hetero atom 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 hetero atom and the carbon atom, or a lone electron pair or an empty electron The resistance tends to decrease because the orbit may easily become the path of conduction electrons or holes.
Further, in the present invention, it is also a preferable embodiment that the vinyl ether compound has no carbon-carbon double bond other than the vinyl ether structure in the vinyl ether compound. Although the carbon-carbon double bond has an electron occupied orbital having a high energy level and a non-electron occupied orbital having a low energy level, these tend to be paths for electrons and holes, and tend to lower the resistance. When the vinyl ether compound contains a carbon-carbon double bond other than the vinyl ether structure, the resistance tends to decrease due to such a mechanism.
In the present invention, the vinyl ether compound is preferably represented by the following formula (C).

［式（Ｃ）中、ｎは、一分子中のビニルエーテル構造の数を示し、１以上４以下の整数である。Ｒはｎ価の炭化水素基である。］
上記ｎは、１以上３以下の整数であることが好ましい。
Ｒは、好ましくは、炭素数１以上２０以下の直鎖又は分岐の飽和又は不飽和の脂肪族炭化水素基、炭素数５以上１２以下の飽和又は不飽和の脂環式炭化水素基、及び炭素数６以上１４以下の芳香族炭化水素基から選択される基であり、該脂環式炭化水素基及び該芳香族炭化水素基は、炭素数１以上４以下の飽和又は不飽和の脂肪族炭化水素基を有していてもよい。
上記Ｒは、より好ましくは炭素数４以上１８以下の直鎖又は分岐の飽和脂肪族炭化水素基である。
該ビニルエーテル化合物としては、例えば、ｎ−オクチルビニルエーテル、２−エチルヘキシルビニルエーテル、ドデシルビニルエーテル、オクタデシルビニルエーテル、ベンジルビニルエーテル、ジシクロペンタジエンビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、トリシクロデカンビニルエーテル、トリメチロールプロパントリビニルエーテル、２−エチル−１，３−ヘキサンジオールジビニルエーテル、２，４−ジエチル−１，５−ペンタンジオールジビニルエーテル、２−ブチル−２−エチル−１，３−プロパンジオールジビニルエーテル、ネオペンチルグリコールジビニルエーテル、ペンタエリスリトールテトラビニルエーテル、及び１，２−デカンジオールジビニルエーテルなどが挙げられる。

[In the formula (C), n represents the number of vinyl ether structures in one molecule, and is an integer of 1 or more and 4 or less. R is an n-valent hydrocarbon group. ]
The above n is preferably an integer of 1 or more and 3 or less.
R is preferably a linear or branched saturated or unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, a saturated or unsaturated alicyclic hydrocarbon group having 5 to 12 carbon atoms, and carbon A group selected from aromatic hydrocarbon groups having a number of 6 or more and 14 or less, wherein the alicyclic hydrocarbon group and the aromatic hydrocarbon group are a saturated or unsaturated aliphatic hydrocarbon having 1 to 4 carbon atoms. It may have a hydrogen group.
R is more preferably a linear or branched saturated aliphatic hydrocarbon group having 4 to 18 carbon atoms.
Examples of the vinyl ether compound include n-octyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, benzyl vinyl ether, dicyclopentadiene vinyl ether, cyclohexane dimethanol divinyl ether, tricyclodecane vinyl ether, trimethylolpropane trivinyl ether, and -Ethyl-1,3-hexanediol divinyl ether, 2,4-diethyl-1,5-pentanediol divinyl ether, 2-butyl-2-ethyl-1,3-propanediol divinyl ether, neopentyl glycol divinyl ether, Examples thereof include pentaerythritol tetravinyl ether and 1,2-decanediol divinyl ether.

  When the liquid developer of the present invention is of an ultraviolet curable type, a photopolymerization initiator, a photopolymerization sensitizer, and a photopolymerization sensitizer can be used in combination with the polymerizable monomer. The photopolymerizable initiator, the photopolymerization sensitizer and the photopolymerization sensitizer do not reduce the volume resistivity of the liquid developer too much, and any known compounds as long as the viscosity does not become too high. But it can be used.

[Toner charge control agent]
The carrier liquid may contain other toner charge control agents together with the polymer compound for the purpose of adjusting the chargeability of the toner particles.
As other toner charge control agents that can be used in combination, known toner charge control agents can be used as long as the volume resistivity of the liquid developer does not decrease too much and the viscosity does not increase too much.
Specific compounds include oils and fats such as linseed oil and soybean oil, alkyd resins, halogen polymers, aromatic polycarboxylic acids, acidic group-containing water-soluble dyes, oxidative condensates of aromatic polyamines, zirconium naphthenate, and naphthenic acid. Cobalt, nickel naphthenate, iron naphthenate, zinc naphthenate, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate, aluminum stearate, cobalt 2-ethylhexanoate, etc. Metal soaps, sulfonic acid metal salts such as petroleum sulfonic acid metal salts and sulfosuccinate metal salts, phospholipids such as lecithin, metal complexes such as salicylic acid and benzylic acid, polyvinylpyrrolidone resins, polyamide resins, and sulfonic acid-containing Resin, hydroxybenzoic acid Body and the like.

In the present invention, when the polymer compound is contained in the toner particles as a charge auxiliary, it is preferable to add a toner charge control agent to the carrier liquid.
The added charge control agent is preferably one that positively charges the toner particles, and a metal salt or a metal complex of an organic acid is suitably used.
Specifically, for example, zirconium naphthenate, cobalt naphthenate, nickel naphthenate, iron naphthenate, zinc naphthenate, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate And metal soaps such as aluminum stearate and cobalt 2-ethylhexanoate, and metal (eg, aluminum, chromium, zinc, zirconium and boron) complexes such as salicylic acid and benzylic acid.
In this case, the addition amount is preferably from 0.01 to 10 parts by mass, and more preferably from 0.05 to 5 parts by mass with respect to 100 parts by mass of the toner particles (solid content). More preferred.

[Toner particles]
The toner particles contain a binder resin and a colorant as constituent components. When the polymer compound is used as a charge auxiliary, the toner particles contain the polymer compound.
(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 a plastic film and is insoluble in a carrier liquid.
Here, regarding “insoluble in carrier liquid”, an index is that the binder resin to be dissolved is 1 part by mass or less with respect to 100 parts by mass of the carrier liquid at a temperature of 25 ° C.
Specific examples of the binder resin include resins such as epoxy resin, polyester resin, (meth) acrylic resin, styrene- (meth) acrylic resin, alkyd resin, polyethylene resin, ethylene- (meth) acrylic resin, and rosin-modified resin. No. If necessary, these can be used alone or in combination of two or more.
The content of the binder resin is not particularly limited, but is preferably 50 to 1000 parts by mass with respect to 100 parts by mass of the colorant.

[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. And those obtained by grafting a resin to the surface of a pigment can be used.
Examples of the pigment include W.I. Herbst, K .; Hunger "Industrial Organic Pigments".
Specific examples of the pigment include, for example, those exhibiting 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, C. 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.
The following are given as those exhibiting red or magenta.
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; I. Butt Red 1,2,10,13,15,23,29,35.
The pigments exhibiting blue or cyan colors include the following.
C. I. Pigment Blue 2, 3, 15: 2, 15: 3, 15: 4, 16, 17;
I. Bat blue 6; I. Acid Blue 45, a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton.
The following are examples of green pigments.
C. I. Pigment Green 7, 8, 36.
The following are examples of orange pigments.
C. I. Pigment Orange 66, 51.
The following are examples of black pigments.
Carbon black, titanium black, aniline black.
The following are examples of the white pigments.
Basic lead carbonate, zinc oxide, titanium oxide, strontium titanate.
For dispersion of the pigment in the toner particles, a dispersing means corresponding to a method for producing the toner particles 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.

When dispersing the pigment, it is also possible to add a pigment dispersant. 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 high molecular weight polycarboxylic acid salt, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, and a fat. Group polycarboxylic acids, naphthalenesulfonic acid formalin condensates, polyoxyethylene alkyl phosphates, and pigment derivatives. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series of Lubrizol.
In addition, as a pigment dispersing aid, a synergist corresponding to various pigments can be used.
These pigment dispersants and pigment dispersing aids are preferably added in an amount of 1 to 50 parts by mass based on 100 parts by mass of the pigment.

[Charge auxiliary agent]
The toner particles may contain other charge auxiliary agents together with the polymer compound for the purpose of adjusting the chargeability of the toner particles.
As the other charge auxiliary agent that can be used in combination, known ones can be used as long as the granulating properties of the toner particles and the pigment dispersibility in the toner particles are not significantly reduced.
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 Soaps, such as metal salts of petroleum-based sulfonic acids and 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 derivative.
There is no particular limitation on the method for incorporating the polymer compound and other charge adjuvants used in the toner particles as charge adjuvants as long as the charge adjuvant can be retained in the toner particles.
For example, in a granulation step of toner particles, a method of adding together with a binder resin and a colorant, and a method of bonding or adsorbing to the toner particle surface by a chemical or physical method after granulating the toner particles. Can be used. It is advisable to select the most suitable method for these methods according to the method for producing the liquid developer.
The charge auxiliary agent added to the toner particles detaches from the toner particles and, when dissolved or dispersed in the carrier liquid, lowers the volume resistivity of the liquid developer or inhibits the action of the charge control agent in the carrier liquid. Or may be. Therefore, it is preferable to select a structure that reduces the solubility in the carrier liquid and improves the affinity of the toner particles with the constituent material.
In addition, when the removal of the charge auxiliary agent into the carrier liquid is remarkable, a method of removing the released charge auxiliary agent from the carrier liquid by a technique such as adsorption with an adsorbent, replacement of the carrier liquid, or dialysis is used. It can also be used.

[Other additives]
In the liquid developer of the present invention, in addition to those described above, if necessary, according to the purpose of improving the compatibility of the recording medium, storage stability, image storability, and other various properties, various known additives may be used. May be used. For example, surfactants, lubricants, fillers, defoamers, ultraviolet absorbers, antioxidants, anti-fading agents, sunscreens, rust inhibitors and the like can be appropriately selected and used.

In the present invention, the 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 and 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 in which a liquid developer is obtained by mixing the obtained dispersion of toner particles, a charge controlling agent, a carrier liquid, and the like can be exemplified.
The coacervation method is described in detail in, for example, JP-A-2003-241439, WO 2007/000974, or WO 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, and the solvent that dissolves the resin is removed from the mixed solution. By depositing the resin, the toner particles having the pigment embedded therein can be dispersed in a solvent that does not dissolve the resin.
On the other hand, the details of the wet pulverization method are described in, for example, WO 2006/126566 or WO 2007/108485.
In the wet pulverization method, the pigment and the binder resin are kneaded at a temperature equal to or higher than the melting point of the binder resin, followed by dry pulverization, and the resulting pulverized material is wet-pulverized in an electrically insulating medium. Can be dispersed inside.
In the present invention, such a known method can be used.
The toner particles preferably have a volume average particle size of 0.05 μm or more and 5 μm or less, and 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 concentration of the toner particles in the liquid developer may be in the range of about 1% by mass to 70% by mass.

[Characteristics of liquid developer]
The liquid developer of the present invention is preferably prepared and used so as to have the following physical properties. That is, the viscosity of the liquid developer is from 0.5 mPa · s to 100 mPa · s at 25 ° C. when the concentration of the toner particles is 2% by mass, from the viewpoint that an appropriate electrophoretic mobility of the toner particles is obtained. Preferably, there is.
Further, the volume resistivity of the liquid developer is preferably 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less from the viewpoint of not lowering the potential of the electrostatic latent image.

The measuring method and the evaluation method used in the present invention will be described below.
(1) Composition analysis The structure of the polymer compound was determined by the following method.
¹ H-NMR and ¹³ C-NMR spectra were measured using ECA-400 (400 MHz) manufactured by JEOL Ltd.
The measurement was performed at 25 ° C. in a deuterated solvent containing tetramethylsilane as an internal standard. Chemical shift values are ppm shift values (δ with respect to tetramethylsilane as an internal standard substance being 0).
Value).

(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 measurement of the molecular weight by GPC was performed as shown below.
A sample was added to the following eluent so that the sample concentration was 1% by mass, and the solution was allowed to stand at room temperature for 24 hours and dissolved. The solution was filtered through a solvent-resistant membrane filter having a pore size of 0.45 μm. And measured under the following conditions.
Apparatus: High-speed GPC GPC-104 (manufactured by Showa Denko KK)
Column: Duplex of GPC HFIP-603, 604 (manufactured by Showa Denko KK)
Eluent: hexafluoroisopropanol (HFIP) (containing 10 mmol / l sodium trifluoroacetate)
Flow rate: 0.2ml / min
Oven temperature: 40 ° C
Sample injection volume: 20 μL
In calculating the molecular weight distribution of the sample, a molecular weight calibration curve created using 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 the toner particles is determined using a dynamic light scattering (DLS) particle size distribution analyzer (trade name: Nanotrack 150, manufactured by Nikkiso Co., Ltd.). Measurements were made in the liquid.

(4) Evaluation of electrophoretic mobility The electrophoretic mobility of the prepared liquid developer was measured as described below.
A sample diluted with a carrier liquid so that the toner particle concentration became 1% by mass was held by capillary force between parallel plate electrodes having a thickness of 300 μm and a width of 20 mm and opposed to each other by 100 μm.
The state of electrophoresis when a potential difference of 100 V was applied between the parallel plate electrodes (electric field intensity 1 × 10 ⁶ V / m) was photographed with a high-speed camera (FASTCAM SA-1 manufactured by Photron) connected to an optical microscope. .
The obtained image was loaded into image processing software ImageJ (developed by Wayne Rasband (NIH)), and the average migration mobility of the particles was calculated by a particle image flow velocity measurement method (PIV method). The migration polarity of the particles was negative when migrated to the positive electrode and positive when migrated to the negative electrode.
The evaluation of the electrophoretic mobility was determined based on 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 and 1 × 10 ⁻⁹ m ² / V · s Less than C: average migration mobility is 3 × 10 ⁻¹⁰ m ² / V · s or more and 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: Average migration mobility is less than 1 × 10 ⁻¹⁰ m ² / V · s Average migration mobility is 7 × 10 ⁻¹⁰ m ² / V · s If it was above (A or B rank), the electrophoretic mobility and the charge amount were high and judged to be good.

  Hereinafter, the present description will be specifically described with reference to examples, but the present invention is not limited to these examples. All "parts" described in Examples are parts by mass.

(Production of polymer compound a)
17.9 parts of 2- (methacryloyloxy) ethyl 2- (trimethylammonio) ethyl phosphate, 82.1 parts of octadecyl methacrylate, and azobis were added to a reaction vessel equipped with a cooling pipe, a stirrer, a thermometer, and a nitrogen introduction pipe. 4.1 parts of isobutyronitrile and 900 parts of n-butanol were charged, and nitrogen bubbling was performed for 30 minutes. The obtained 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, the polymer was dried under reduced pressure at 50 ° C. and 0.1 kPa or less to obtain a polymer compound a.
When the obtained polymer compound a was analyzed by the above-mentioned analysis method, the weight-average molecular weight (Mw) was 11,800, and the structural unit represented by the formula (1) contained 21 mol% in all the monomer units. I confirmed that.

(Production of polymer compound b)
The above polymer compound except that 17.1 parts of 2- (acryloyloxy) ethyl 2- (trimethylammonio) ethyl phosphate are used instead of 2- (methacryloyloxy) ethyl phosphate 2- (trimethylammonio) ethyl Polymer compound b was produced in the same manner as in the production of a.

(Production of polymer compound c)
The above polymer compound except that 20.5 parts of 2- (methacryloyloxy) ethyl 2- (triethylammonio) ethyl phosphate is used instead of 2- (methacryloyloxy) ethyl 2- (trimethylammonio) ethyl phosphate Polymer compound c was produced in the same manner as in the production of a.

(Production of polymer compound d)
Except that 18.8 parts of 2- (methacryloyloxy) -1-methylethyl 2- (trimethylammonio) ethyl phosphate are used in place of 2- (methacryloyloxy) ethyl phosphate 2- (trimethylammonio) ethyl Polymer compound d was produced in the same manner as in the production of polymer compound a.

(Production of polymer compound e)
Using 19.6 parts of 2- (methacryloyloxy) ethyl 1,2-dimethyl-2- (trimethylammonio) ethyl phosphate instead of 2- (methacryloyloxy) ethyl 2- (trimethylammonio) ethyl phosphate Except for the above, a polymer compound e was produced in the same manner as in the production of the polymer compound a.

(Production of polymer compound f)
Polymer compound f was produced in the same manner as in the production of polymer compound a, except that 78.7 parts of octadecyl acrylate was used instead of octadecyl methacrylate.

(Production of polymer compound g)
Polymer compound g was produced in the same manner as in the production of polymer compound a, except that 48.1 parts of octyl methacrylate were used instead of octadecyl methacrylate.

(Production of polymer compound h)
Polymer compound h was prepared in the same manner as in the preparation of polymer compound a, except that 34.5 parts of butyl methacrylate was used instead of octadecyl methacrylate.

(Production of polymer compound i)
Other than using 136.4 parts of 2- (methacryloyloxy) ethyl 2- (dimethyldodecylammonio) ethyl phosphate instead of 2- (methacryloyloxy) ethyl phosphate 2- (trimethylammonio) ethyl and octadecyl methacrylate A polymer compound i was produced in the same manner as in the production of the polymer compound a.

(Production of Comparative Polymer Compound j)
2- (methacryloyloxy) ethyl phosphate 2- (methacryloyloxy) ethyltrimethylammonium chloride Instead of 2- (methacryloyloxy) ethyltrimethylammonium chloride, 12.6 parts are used in the same manner as in the production of the polymer compound a. Comparative polymer compound j was produced.

  Table 1 shows the composition ratios and weight average molecular weights (Mw) of the polymer compounds a to j produced as described above. In Table 1, X represents a bonding site of the structural unit represented by the formula (1) with the polymer main chain, and X ′ represents a bonding site of the structural unit represented by the formula (1) with the phosphate site. Y represents a binding site of the structural unit represented by the formula (1) to the phosphate ester site, and Y ′ represents a binding site of the structural unit represented by the formula (1) to the quaternary ammonium salt site. , Z each represent a binding site of the structural unit represented by the formula (2) with the polymer main chain.

<Evaluation of polymer compound as toner charge control agent>
<Example 1>
[Production of toner particle dispersion]
Into a reaction vessel equipped with a stirrer and a thermometer, 25 parts of Nucrel N1525 (ethylene-methacrylic acid resin, manufactured by DuPont-Mitsui Polychemicals) and 75 parts of Isopar L (manufactured by ExxonMobil) are charged at 200 rpm. While stirring, the temperature was raised to 130 ° C. over 1 hour in an oil bath. After holding at 130 ° C. for 1 hour, the mixture was gradually cooled at a temperature lowering rate of 15 ° C. per hour to prepare a binder resin dispersion. The obtained binder resin dispersion was in the form of a white paste.
60 parts of the above binder resin dispersion, 5 parts of Pigment Blue 15: 3, and 35 parts of Isopar L were filled together with zirconia beads having a diameter of 0.5 mm into a planetary bead mill (Fritsch Classic Line P-6), and room temperature was added. At 200 rpm for 4 hours to obtain a toner particle dispersion (solid content: 20% by mass). The toner particles contained in the obtained toner particle dispersion had a volume average particle size of 0.85 μm.
[Preparation of Toner Charge Control Agent Dispersion]
In a reaction vessel equipped with a stirrer and a thermometer, 6.2 parts of the polymer compound a and 68.2 parts of tetrahydrofuran (THF) were charged, and the temperature was raised to 60 ° C. to dissolve the polymer compound a. After charging 71.3 parts of Isopar L, THF was distilled off under reduced pressure at 50 ° C. and 4 kPa to obtain a charge control agent dispersion as a transparent reverse micelle liquid.
[Preparation of liquid developer]
A liquid developer of Example 1 was prepared by mixing 10.0 parts of the above toner particle dispersion, 0.125 parts of a toner charge control agent dispersion, and 89.98 parts of Isopar L.

<Examples 2 to 9>
Liquid developers of Examples 2 to 9 were produced in the same manner as in Example 1 except that polymer compounds b to i were used instead of polymer compound a.

<Example 10>
[Production of binder resin]
In a reaction vessel equipped with a reflux condenser, a water / alcohol separator, a nitrogen gas inlet pipe, a thermometer and a stirrer, 1500 parts of ethylene oxide adduct of bisphenol A (Sigma-Aldrich) and terephthalic acid (Sigma-Aldrich) Was added and nitrogen gas was introduced with stirring, and a dehydration / dealcoholization polycondensation reaction was performed at a temperature of 200 to 240 ° C. After one hour, the temperature of the reaction system was lowered to 100 ° C. or lower, and the polycondensation was stopped. The obtained polyester resin had Mw of 9,000, a number average molecular weight (Mn) of 2,100, a glass transition temperature (Tg) of 68 ° C, and an acid value of 12.0 mgKOH / g.
In the following steps, a liquid developer of Example 10 was produced in the same manner as in Example 1 except that the polyester resin produced above was used instead of Nuclell N1525 as a binder resin.

<Example 11>
A liquid developer of Example 11 was manufactured in the same manner as in Example 1 except that dodecyl vinyl ether (manufactured by Sigma-Aldrich) was used instead of Isopar L as the carrier liquid.

<Example 12>
[Production of toner particle dispersion]
A toner particle dispersion was produced in the same manner as in Example 1 except that the polyester resin produced in Example 10 was used instead of Nuclell N1525, and dodecyl vinyl ether was used instead of Isopar L.
[Preparation of Toner Charge Control Agent Dispersion]
A toner charge control agent dispersion was prepared in the same manner as in Example 1 except that dodecyl vinyl ether was used instead of Isopar L.
[Preparation of liquid developer]
After mixing 0.125 parts of the toner charge control agent dispersion, 79.04 parts of dodecyl vinyl ether, and 9.68 parts of cyclohexane dimethanol divinyl ether with 10.0 parts of the above toner particle dispersion, N-hydroxy was used as a photopolymerization initiator. 0.29 parts of naphthalimido nonafluorobutanesulfonate, 0.48 parts of 2,4-diethylthioxanthone as a photopolymerization sensitizer, and 0.48 parts of 1,4-diethoxynaphthalene as a photopolymerization sensitizer Was mixed and dissolved to produce an ultraviolet-curable liquid developer. The composition of the carrier liquid of the liquid developer was referred to as "ultraviolet curable vinyl ether mixture 1."

<Example 13>
[Preparation of liquid developer]
To 10.0 parts of the toner particle dispersion prepared in Example 12, 0.125 part of the toner charge control agent dispersion prepared in Example 12, 16.10 parts of dodecyl vinyl ether, and 2-butyl-2-ethyl-1 After mixing 72.63 parts of 2,3-propanediol divinyl ether, 0.29 parts of N-hydroxynaphthalimidononafluorobutanesulfonate as a photopolymerization initiator and 2,4-diethylthioxanthone 0.48 as a photopolymerization sensitizer Parts and 0.48 part of 1,4-diethoxynaphthalene as a photopolymerization sensitizing aid were mixed and dissolved to produce an ultraviolet-curable liquid developer. The composition of the carrier liquid of the liquid developer was referred to as “ultraviolet curable vinyl ether mixture 2”.
The volume resistivity and the viscosity at 25 ° C. of the above Isopar L and dodecyl vinyl ether were 8.4 × 10 ¹³ Ω · cm, 1.2 mPa · s, and 2.7 × 10 ¹² Ω · cm, respectively. It was 2.8 mPa · s. The volume resistivity and the viscosity at 25 ° C. of cyclohexanedimethanol divinyl ether and 2-butyl-2-ethyl-1,3-propanediol divinyl ether are 1.3 × 10 ¹⁰ Ω · cm and 4. The values were 2 mPa · s, 9.4 × 10 ¹² Ω · cm, and 2.7 mPa · s.

<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 a was not used as the charge control agent.

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

<Comparative Example 3>
A liquid developer of Comparative Example 3 was produced in the same manner as in Example 1 except that polymer compound j was used instead of polymer compound a.
The results of evaluation of the electrophoretic mobility of the liquid developer produced above are shown in Table 2 below.

  As shown in Table 2, when the high molecular compounds a to i are added to the carrier liquid as the charge control agent, the negative chargeability of the toner particles is improved, and the liquid developer has a high electrophoretic mobility. I understand.

<Evaluation of polymer compound as charge auxiliary>
<Example 14>
[Production of toner particles]
Into a reaction vessel equipped with a stirrer and a thermometer, 25 parts of Nucrel N1525 (ethylene-methacrylic acid resin manufactured by DuPont-Mitsui Polychemicals Co., Ltd.) and 75 parts of Isopar L (manufactured by ExxonMobil) are charged and stirred at 200 rpm. While heating, the temperature was raised to 130 ° C. over 1 hour in an oil bath. After holding at 130 ° C. for 1 hour, the mixture was gradually cooled at a temperature lowering rate of 15 ° C. per hour to prepare a binder resin dispersion. The obtained binder resin dispersion was in the form of a white paste.
60 parts of the binder resin dispersion, 0.2 part of a polymer compound a as a charge auxiliary,
5 parts of Pigment Blue 15: 3 and 35.8 parts of Isopar L are filled together with zirconia beads having a diameter of 0.5 mm into a planetary bead mill (classical line P-6 manufactured by Fritsch) and pulverized at room temperature for 4 hours at 200 rpm. Thus, 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.
[Preparation of Toner Charge Control Agent Dispersion]
6.2 parts of aluminum salicylate complex (Bontron E-108, manufactured by Orient Chemical Co., Ltd.) and 71.3 parts of Isopar L were mixed and dispersed at room temperature for 10 minutes using an ultrasonic homogenizer to obtain a charge control agent dispersion. .
[Preparation of liquid developer]
A liquid developer of Example 14 was prepared by mixing 0.125 parts of a toner charge control agent dispersion and 89.98 parts of Isopar L with 10.0 parts of the toner particle dispersion.

<Example 15>
A liquid developer of Example 15 was produced in the same manner as in Example 14 except that a chromium salicylate complex (Bontron E-81 manufactured by Orient Chemical Co., Ltd.) was used instead of the aluminum salicylate complex as a toner charge control agent.

<Example 16>
A liquid developer of Example 16 was produced in the same manner as in Example 14 except that a zinc salicylate complex (Bontron E-84, manufactured by Orient Chemical Co., Ltd.) was used instead of the aluminum salicylate complex as a toner charge control agent.

<Example 17>
A liquid developer of Example 17 was manufactured in the same manner as in Example 14 except that a zirconium salicylate complex (TN-105 manufactured by Hodogaya Chemical Industry Co., Ltd.) was used instead of the aluminum salicylate complex as the toner charge control agent.

<Example 18>
A liquid developer of Example 18 was produced in the same manner as in Example 14 except that a boron benzylate complex (LR-147, manufactured by Nippon Carlit Co., Ltd.) was used instead of the aluminum salicylate complex as the toner charge control agent.

<Example 19>
The above-described procedure was repeated except that a solution in which 6.7 parts of zirconium naphthenate (manufactured by Kishida Chemical Co., Ltd.) was dissolved in 24.3 parts of Isopar L instead of the Isopar L dispersion of aluminum salicylate complex was used as the toner charge control agent dispersion. A liquid developer of Example 19 was produced in the same manner as in Example 14.

<Example 20>
A liquid developer of Example 20 was produced in the same manner as in Example 14 except that the polyester resin produced in Example 10 was used instead of Nuclell N1525 as the binder resin.

<Example 21>
A liquid developer of Example 21 was produced in the same manner as in Example 14 except that dodecyl vinyl ether (manufactured by Sigma-Aldrich) was used instead of Isopar L as the carrier liquid.

<Example 22>
A liquid developer of Example 22 was produced in the same manner as in Example 14 except that the aluminum salicylate complex was not used as the toner charge control agent.

<Example 23>
A liquid developer of Example 23 was produced in the same manner as in Example 14 except that the polymer compound i was used as the charge auxiliary.

<Example 24>
[Production of toner particle dispersion]
A toner particle dispersion was produced in the same manner as in Example 14 except that the polyester resin produced in Example 10 was used in place of Nuclell N1525 as the binder resin, and dodecyl vinyl ether was used in place of Isopar L as the carrier liquid.
[Preparation of Toner Charge Control Agent Dispersion]
A toner charge control agent dispersion was prepared in the same manner as in Example 14 except that dodecyl vinyl ether was used instead of Isopar L.
[Preparation of liquid developer]
After mixing 0.125 parts of the toner charge control agent dispersion, 79.04 parts of dodecyl vinyl ether, and 9.68 parts of cyclohexane dimethanol divinyl ether with 10.0 parts of the above toner particle dispersion, N-hydroxy was used as a photopolymerization initiator. 0.29 parts of naphthalimido nonafluorobutanesulfonate, 0.48 parts of 2,4-diethylthioxanthone as a photopolymerization sensitizer, and 0.48 parts of 1,4-diethoxynaphthalene as a photopolymerization sensitizer Was mixed and dissolved to produce an ultraviolet-curable liquid developer. The composition of the carrier liquid of the liquid developer was referred to as “ultraviolet curable vinyl ether mixture 3”.

<Comparative Example 4>
A liquid developer of Comparative Example 4 was produced in the same manner as in Example 14 except that the polymer compound a and the aluminum salicylate complex were not used.

<Comparative Example 5>
A liquid developer of Comparative Example 5 was produced in the same manner as in Example 14 except that lecithin (derived from soybean manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of the polymer compound a.

<Comparative Example 6>
A liquid developer of Comparative Example 6 was produced in the same manner as in Example 14 except that polymer compound j was used instead of polymer compound a.
The results of evaluating the electrophoretic mobility of the liquid developer produced above are shown in Table 3 below.

  As shown in Table 3, when the polymer compounds a and i are added to the toner particles as the charge auxiliary, the positive chargeability of the toner particles is improved, and the liquid developer has a high electrophoretic mobility. I understand.

  According to the present invention, a toner charge control agent and a charge auxiliary agent that further improve the charge amount and electrophoretic mobility of toner particles are provided, and a liquid developer that can cope with an increase in the process speed of an image forming apparatus is provided. be able to.

Claims (7)

A liquid developer containing toner particles and a carrier liquid,
A liquid developer comprising a polymer compound having a structural unit represented by the following formula (1) in either the toner particles or the carrier liquid.

[In the formula (1), R _{1 to} R ₄ each independently represent any of a hydrogen atom and an alkyl group, and A represents a single bond, a carbonyl group, an alkylene group, an arylene group, and —COOR ₇ — , -COOR _7- is bonded to the carbon atom to which R ₁ is bonded, and R ₇ represents alkylene having 1 to 4 carbon atoms), and B represents any of an alkylene group and an arylene group. Represents. ]   The liquid developer according to claim 1, wherein the carrier liquid contains a polymer compound having a structural unit represented by the formula (1). The liquid developer according to claim 1, wherein the carrier liquid contains a copolymer having a structural unit represented by the formula (1) and a structural unit represented by the following formula (2). 4.

[In the formula (2), R ₅ represents any one of a hydrogen atom and an alkyl group, and R ₆ represents any one of an alkyl group, a carboxylic ester group, a carboxylic amide group, an alkoxy group, and an aryl group. ]   The liquid developer according to claim 1, wherein the toner particles contain a polymer compound having a structural unit represented by the formula (1).   The liquid developer according to claim 4, wherein the carrier liquid contains a metal salt or a metal complex of an organic acid.   The liquid developer according to any one of claims 1 to 5, wherein the toner particles contain a polyester resin. The liquid developer according to claim 1, wherein the carrier liquid contains a vinyl ether compound having a volume resistivity of 1 × 10 ⁹ Ω · cm or more and 1 × 10 ¹⁵ Ω · cm or less.