JP2017054044A - Polymeric dispersant for liquid developer, liquid developer, and printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymeric dispersant for a liquid developer that gives an excellent image density and has excellent fixability and cold off-set resistance and excellent long-term storage stability.SOLUTION: The polymeric dispersant for a liquid developer is prepared by copolymerizing at least an ethylenically unsaturated monomer having an amino group, an ethylenically unsaturated monomer having at least one acid group selected from a carboxylic acid, a sulfonic acid, a phosphoric acid and a boronic acid, and an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms.SELECTED DRAWING: None

Description

  The present invention relates to a polymer dispersant for liquid developer, a liquid developer, and a printed matter.

  In an electrophotographic image forming apparatus using a liquid developer, a developer in which finely divided toner particles are dispersed in a carrier liquid is used. The electrostatic latent image formed on the photoreceptor by exposure is developed using toner particles in a carrier liquid. After development, the obtained electrostatic latent image is transferred, dried and fixed on a recording medium such as paper to form an image.

  In the liquid developer, since the toner particles are finely pulverized and dispersed under a wet condition, the toner particles can be made finer than a dry powder toner. Further, since the liquid developer uses an insulating liquid carrier liquid as a carrier, there is no problem due to scattering of toner particles in the image forming apparatus. Therefore, an image forming apparatus using a liquid developer has a feature that a high-definition image can be formed.

  The liquid developer is obtained by dispersing toner particles in an electrically insulating carrier liquid as described above, and the toner particles are required to have colorability, fixability, chargeability, and dispersion stability. The toner particles are composed of additives such as a colorant, a binder resin, and a dispersant. In order to obtain an excellent image, the toner particles are stably dispersed and charged stably. (For example, refer to Patent Documents 1 and 2).

  In order to uniformly disperse toner particles in an electrically insulating carrier liquid and to maintain better storage stability, investigations have been made on dispersants. However, if the toner particles are stably dispersed and the storage stability is improved, the amount of heat required for the toner particles to melt, contact, and coalesce in the fixing process during image output increases, and the substrate The fixability of the ink is reduced. In addition, a part of incompletely melted toner particles adheres to the surface of the thermocompression roller and causes a cold offset phenomenon in which the toner is transferred to the next paper. Therefore, it has been a difficult problem to achieve both fixing property and cold offset resistance and storage stability. Therefore, in order to achieve both the fixability and the storage stability of the liquid developer, studies have been made on a polymer dispersant that hardly inhibits the fixability (see, for example, Patent Document 3). However, there is a problem that the chargeability of the toner particles is lowered due to the influence of the polymer dispersant and a sufficient image density cannot be obtained, and the long-term stability of the image is lowered and the color development and color reproducibility are impaired. there were.

Japanese Patent No. 3248243 Patent No. 5191659 Patent No. 5003455

  As described above, the liquid developer has a room for improvement in obtaining a sufficient image density, achieving both storage stability, fixing property and cold offset resistance, and excellent image quality. was there. That is, there has been a demand for a liquid developer excellent in output image, which has excellent fixability and cold offset resistance and has excellent storage stability over a long period of time.

  Accordingly, an object of the present invention is to provide a polymer dispersant for a liquid developer that can obtain an excellent image density, is excellent in fixability and cold offset resistance, and is excellent in storage stability over a long period of time. . The present invention also provides a liquid developer capable of obtaining an excellent image density, excellent in fixability and cold offset resistance, and excellent in storage stability over a long period of time, and a printed matter obtained using the same. With the goal.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-described problems can be solved by the following embodiment, and have completed the present invention.

  The present invention relates to an ethylenically unsaturated monomer (c-1) having an amino group and ethylene having at least one acid group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group. Polymeric Dispersant for Liquid Developers Comprising a Copolymer of an Ethylenically Unsaturated Monomer (c-2) and an Ethylenically Unsaturated Monomer (c-3) Having an Alkyl Group of 9 to 24 Carbons About.

  In the present invention, the polymer dispersant has a weight average molecular weight Mw of 500 to 40,000, an amine value of 5 to 150 mgKOH / g, and an acid value of 5 to 40 mgKOH / g. The above-mentioned polymer dispersant for a liquid developer.

In the present invention, the copolymer comprises the monomer (c-1), the monomer (c-2), the monomer (c-3), and the following general formula (1). The above-mentioned polymer dispersant for liquid developer, which is a copolymer with an ethylenically unsaturated monomer (c-4) represented by
General formula (1)
CH ₂ = C (R ¹ ) COO (AO) _n R ²
(Wherein R ¹ represents a hydrogen atom or a methyl group,
R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms,
n represents an integer of 1 to 200,
A represents an alkylene group having 2 to 4 carbon atoms. )

  The present invention also provides a liquid developer comprising a binder resin (A) containing at least a polyester resin, a colorant (B), a polymer dispersant (C), and a carrier liquid (D). The liquid developer is characterized in that the agent (C) is the polymer dispersant.

  In the present invention, the binder resin (A) has an acid value of 5 to 40 mgKOH / g, and a glass transition temperature (Tg) of 50 to 65 ° C. It relates to a developer.

  The present invention also relates to the liquid developer, wherein the carrier liquid (D) is an aliphatic hydrocarbon.

  In the present invention, the ratio of primary carbon is 55% or more and the ratio of secondary carbon is 30% or less with respect to the total number of primary to tertiary carbons of the aliphatic hydrocarbon. The present invention relates to the liquid developer.

  In addition, the present invention relates to the liquid developer, wherein the carrier liquid (D) has a dry point of 230 to 360 ° C. and an aniline point of 75 to 100 ° C.

  The present invention also relates to a printed matter that is a developer of the liquid developer.

  According to an embodiment of the present invention, it is possible to provide a polymer dispersant for a liquid developer that can obtain an excellent image density, has excellent fixability and cold offset resistance, and has excellent storage stability over a long period of time. Can do. Further, according to another embodiment of the present invention, a liquid developer capable of obtaining an excellent image density, excellent in fixability and cold offset resistance, and excellent in storage stability over a long period of time, and using the same The obtained printed matter can be provided.

Hereinafter, the present invention will be described in detail.
The polymer dispersant according to the embodiment of the present invention includes at least an ethylenically unsaturated monomer (c-1) having an amino group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group. An ethylenically unsaturated monomer (c-2) having at least one acid group selected from the above and an ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms are copolymerized. It is a great feature. Further, the liquid developer according to another embodiment of the present invention contains at least a binder resin (A), a colorant (B), a polymer dispersant (C), and a carrier liquid (D). The molecular dispersant (C) is the polymer dispersant. In the liquid developer, the binder resin (A) and the colorant (B) are present as toner particles.

  The polymer dispersant (C) of the present invention is obtained by polymerizing an ethylenically unsaturated monomer (c-1) having an amino group, and preferably has a specific amine value, whereby The adsorbing rate of the polymer dispersant (C) is increased, the pulverization property of the toner particles is improved, the average particle size of the toner particles is small, and a liquid developer having a low viscosity can be efficiently obtained, the image density is high, and the color is developed. An image having excellent properties can be obtained. In addition, because of its excellent adsorptivity to toner particles, a liquid developer having excellent dispersion stability can be obtained, and stable images (printed images by copying machines, printed images by printers, etc.) and excellent storage stability can be obtained over a long period of time. A liquid developer having properties is obtained. The polymer dispersant (C) polymerizes an ethylenically unsaturated monomer (c-2) having an acid group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group. As a result, an acid-base reaction with the amino group to be copolymerized generates a charge, and the charge repulsion improves the dispersion stability of the toner particles, thereby obtaining a liquid developer having excellent storage stability. It is done. Furthermore, the polymer dispersant (C) is obtained by polymerizing an ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms, so that it can be dissolved in the carrier liquid (D). A liquid developer having improved image quality, excellent pulverization and dispersion stability of toner particles, and stable chargeability of toner particles in the carrier liquid (D), high image density, and excellent color development. Can be obtained.

  Hereinafter, the binder (A), the colorant (B), and the carrier liquid (D) contained in the polymer dispersant (C) according to the embodiment of the present invention and the liquid developer according to the embodiment of the present invention. ) Will be described in detail.

(Toner particles)
The toner particles used in the liquid developer include at least the binder resin (A) and the colorant (B), and it is also preferable to use additives such as a pigment dispersant, a charge control agent, and a release agent. The polymer dispersant (C) is preferably added when the toner particles are wet-dispersed in the carrier liquid (D), but can also be added to the toner particles when the toner particles are prepared.

(Binder resin (A))
In general, the binder resin has a function of uniformly dispersing a colorant such as a pigment or a dye in the resin and a function as a binder when fixing to a substrate such as paper. Examples of binder resins that can be used include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer Styrene copolymers such as polymers, styrene- (meth) acrylic acid ester copolymers, styrene-acrylonitrile copolymers, styrene-vinyl alkyl ether copolymers, styrene-butadiene copolymers, and crosslinked styrene copolymers. Polymer: Polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, polyester resin, polyurethane resin, polyamide resin, epoxy resin, petroleum resin, etc. It is done.

  The binder resin (A) used in the liquid developer preferably contains at least a polyester resin (a-1) from the viewpoints of pigment dispersibility, grindability, and fixability. Furthermore, the binder resin (A) preferably exhibits a colorless, transparent, white, or light color so as not to inhibit the hue of the color material of each color.

  The polyester resin (a-1) is preferably a thermoplastic polyester, and is preferably obtained by polycondensation of a divalent or trivalent or higher alcohol component and an acid component such as a carboxylic acid.

  Examples of the alcohol component include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, Diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, bisphenol A, hydrogenated bisphenol A-1,4-bis (hydroxy Methyl) cyclohexane, divalent alcohols such as bisphenol derivatives represented by the following general formula (2); glycerol, diglycerol, sorbit, butanetriol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaery Trihydric or higher alcohols such as Lithol; and the like. These are used alone or in combination of two or more.

General formula (2)

 (In General Formula (2), R is an ethylene group or a propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)

  Examples of the acid component include divalent carboxylic acids such as benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride, or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, and sebacic acid, or anhydrides thereof. Succinic acid substituted with an alkyl group having 16 to 18 carbon atoms or an anhydride thereof; Unsaturated dicarboxylic acid such as fumaric acid, maleic acid, citraconic acid, itaconic acid or the anhydride; cyclohexanedicarboxylic acid; naphthalenedicarboxylic acid Diphenoxyethane-2,6-dicarboxylic acid or an anhydride thereof; and the like. Examples of the trivalent or higher carboxylic acid serving as a crosslinking component include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, benzophenonetetracarboxylic acid, and anhydrides thereof. These are used alone or in combination of two or more.

  Preferred alcohol components are those obtained by adding alkylene oxide (preferably 2 to 3 moles) to bisphenol A, ethylene glycol, neopentyl glycol, and the like. Preferred acid components are phthalic acid, terephthalic acid, isophthalic acid or anhydrides thereof; succinic acid, n-dodecenyl succinic acid or anhydrides thereof; dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride; trimellitic acid or anhydride thereof Tricarboxylic acids such as products.

  In the polycondensation of the polyester resin (a-1), the reaction may be promoted using a known and usual reaction catalyst such as at least one metal compound selected from antimony, titanium, tin, zinc and manganese. Specific examples of the reaction catalyst include di-n-butyltin oxide, stannous oxalate, and antimony trioxide. The addition amount of these reaction catalysts is usually preferably about 0.001 to 0.5 mol% with respect to the acid component in the obtained polyester resin (a-1).

  As the polycondensation method, a known bulk polymerization method can be used, and the molecular weight of the polyester resin, the kind of the carboxylic acid to be reacted to control the glass transition temperature, the molar ratio, the reaction temperature, The reaction time, reaction pressure, catalyst, etc. may be adjusted. Furthermore, it is also possible to use a commercial item as a polyester resin. For example, there are Diacron ER-502 and Diacron ER-508 (both manufactured by Mitsubishi Rayon Co., Ltd.).

  In the present invention, the binder resin (A) is used in order to improve pulverization and obtain dispersion stability, to have a low relative dielectric constant, to improve chargeability, and to obtain good color developability and image density. In addition to the polyester resin (a-1), at least one resin (a-2) selected from the group consisting of styrene resin, acrylic resin, and styrene-acrylic copolymer resin (hereinafter simply referred to as resin (a) -2).) Is particularly preferred.

The styrene-acrylic copolymer resin is obtained by polymerizing at least one of styrene monomers and at least one of (meth) acrylic acid and (meth) acrylic acid esters. Styrene monomers used for the resin (a-2) include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene and the like.

  Examples of (meth) acrylic acid esters used in the resin (A-2) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) Isobutyl acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, dimethylaminoethyl acrylate, (meth) Examples include diethylaminoethyl acrylate. A preferred styrenic monomer is styrene. Preferred (meth) acrylic acid esters are butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like.

  Moreover, in order to make the molecular weight of resin (a-2) larger, a polyfunctional monomer can be used as a crosslinking agent. Specifically, divinylbenzene, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri ( And (meth) acrylate.

  The resin (a-2) can be obtained by a known polymerization method such as a suspension polymerization method, a solution polymerization method, or an emulsion polymerization method. For example, to control the molecular weight and glass transition temperature of a styrene-acrylic copolymer resin, the type, molar ratio, reaction temperature and reaction of the styrene monomer, (meth) acrylic acid and (meth) acrylic acid esters What is necessary is just to adjust time, reaction pressure, a polymerization initiator, a crosslinking agent, etc. Furthermore, it is also possible to use a commercial item as a styrene-acrylic copolymer resin. For example, there are ALMATEX CPR100, CPR200, CPR300, CPR600B (Mitsui Chemicals).

  In order to obtain a binder resin (A) that is more uniformly dispersed by mixing the polyester resin (a-1) and the resin (a-2), the polyester resin (a-1) and the resin (a-2) Prepared separately and then mixed; in the presence of either one of the polyester resin (a-1) and the resin (a-2), the other resin monomer is added and polymerized, etc. There is. The latter is desirable for obtaining a more uniformly dispersed binder resin. Usually, after the polyester resin (a-1) is polycondensed by bulk polymerization, the obtained polyester resin (a-1) is dissolved in a solvent. In such a system, a method of synthesizing the resin (a-2) by solution polymerization while heating as necessary and removing the solvent is preferable. Furthermore, it is also preferable to synthesize by a known method described in Japanese Patent No. 3531980 and Japanese Patent Application Laid-Open No. 2006-178296.

  Moreover, when producing polyester resin (a-1) and resin (a-2) separately, or when using commercially available polyester resin and resin (a-2), polyester resin (a-1). And the resin (a-2) can be mixed to obtain the binder resin (A). At this time, either method may be used, in which both are dissolved in a solvent and mixing and desolvation are performed, or melt kneading is performed.

(Acid value)
The acid value of the binder resin (A) is preferably in the range of 5 to 40 mgKOH / g. More preferably, it is 10-30 mgKOH / g. The acid value can be measured using a “potentiometric automatic titrator AT-610” manufactured by Kyoto Electronics Industry Co., Ltd.

  When the acid value of the binder resin (A) is 5 mgKOH / g or more, adsorption due to salt formation with the amine of the polymer dispersant (C) is sufficient, and the pulverizability in wet pulverization is improved. Furthermore, since the dispersion stability of the toner particles is improved, the toner particles are prevented from agglomerating during long-term storage, and excellent storage stability can be obtained. Further, when the acid value is 40 mgKOH / g or less, the chargeability of the toner particles to which the polymer dispersant (C) is adsorbed becomes high, the transfer of the toner particles to the substrate is good, and a sufficient image density is obtained. be able to.

(Glass transition temperature (Tg))
The glass transition temperature of the binder resin (A) is preferably in the range of 50 to 65 ° C. More preferably, it is 50-60 degreeC. The glass transition temperature was 10 mg for a sample using a “differential scanning calorimeter DSC-60 PLUS” manufactured by Shimadzu Corporation under the conditions of a start temperature of 25 ° C., an end temperature of 150 ° C., and a temperature increase rate of 10.0 ° C./min. It was measured using.

  When the glass transition temperature of the binder resin (A) is 50 ° C. or higher, the thermal stability of the binder resin (A) is good, the polymer dispersant (C) is less detached from the toner particles, and is stored. The toner dispersion stability at the time is improved, and the initial toner state can be maintained. Further, when the glass transition temperature is 65 ° C. or less, the liquid developer has a low amount of heat for melting and coalescing of the toner particles adsorbed by the polymer dispersant (C), and has good fixability and cold offset resistance. Can be obtained.

(Softening temperature (T4))
The softening temperature of the binder resin (A) is preferably in the range of 80 to 140 ° C. More preferably, it is the range of 90 to 130 degreeC. The softening temperature was “Flow Tester CFT-500D” manufactured by Shimadzu Corporation, starting temperature 40 ° C., heating rate 6.0 ° C./min, test load 20 kgf, preheating time 300 seconds, die hole diameter 0.5 mm. The temperature when 4 mm of 1.0 g of the sample flows out under the condition of the die length of 1.0 mm is measured as the softening temperature (T4).

  When the softening temperature of the binder resin (A) is 80 ° C. or higher, it is not excessively softened during kneading, so that the dispersibility of the colorant (B) is improved and a sufficient image density as a liquid developer is obtained. be able to. Furthermore, in the fixing process during image output, the toner particles come into contact with the surface of the thermocompression roller in a molten state, so the cohesive force of the toner particles is smaller than the adhesive force between the substrate and the thermocompression roller, and part of it is completely The toner particles adhere to the surface of the thermocompression roller without being adhered to the surface, and the hot offset phenomenon that the toner particles are transferred to the next paper is less likely to occur. Further, when the softening temperature is 140 ° C. or lower, good fixability is obtained, the grindability is improved, and the color developability is enhanced.

(Average molecular weight)
The binder resin (A) has a weight average molecular weight (Mw) of 2,000 to 100 in terms of molecular weight measured by gel permeation chromatography (GPC) from the viewpoint of offset resistance, fixing property and image quality characteristics. 5,000 are preferable, and 5,000 to 50,000 are more preferable. When the weight average molecular weight (Mw) of the binder resin (A) is 2,000 or more, hot offset resistance, color reproducibility, and dispersion stability are improved. Cold offset property is improved. In addition, the binder resin (A) is a type having a molecular weight distribution curve of two peaks comprising a specific low molecular weight condensation polymer component and a specific high molecular weight condensation polymer component, or a single molecular weight distribution curve. Any of the types having

  In addition, the molecular weight and molecular weight distribution by said GPC can be measured on the following conditions using the gel permeation chromatography (HLC-8220) by Tosoh Corporation, for example. The column is stabilized in a 40 ° C. heat chamber, tetrahydrofuran (THF) as a solvent is allowed to flow through the column at this temperature at a flow rate of 0.6 mL / min, and 10 μL of a sample solution dissolved in THF is injected for measurement. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts.

Ten standard polystyrene samples with a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation are used as a standard polystyrene sample for preparing a calibration curve. An RI (refractive index) detector is used as the detector. In addition, three TSKgel SuperHM-M (made by Tosoh Corporation) are used for the column.

  The measurement sample is prepared as follows. Place the sample in THF and let stand for several hours, then shake well, mix well with THF until the sample is no longer united, and let stand for more than 12 hours. At this time, the standing time in THF is set to be 24 hours or longer. Thereafter, the obtained solution is passed through a sample processing filter to obtain a sample solution for GPC measurement. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / mL.

  The content of the binder resin (A) contained in the toner particles is preferably 60 to 95 parts by mass, more preferably 70 to 90 parts by mass with respect to 100 parts by mass of the toner particles. When it is 60 parts by mass or more, the fixing property and offset resistance are improved, and when it is 95 parts by mass or less, the ratio of the binder resin (A) to the colorant (B) becomes small, and the toner particles The coloring power is improved and the image density is increased.

(Colorant (B))
As the colorant (B), yellow, magenta, cyan, and black organic pigments shown below; organic dyes and salt-forming compounds thereof; carbon black; magnetic substances and the like are preferably used. These can be used alone or in admixture of two or more. The colorant (B) is preferably insoluble in the carrier liquid (D).

  As the yellow colorant, it is preferable to use a yellow organic pigment or a salt forming compound of a yellow dye. Examples of yellow organic pigments include benzimidazolone compounds, condensed azo compounds, isoindolinone compounds, anthraquinone compounds, quinophthalone compounds, azo metal complex compounds, methine compounds, and allylamide compounds. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 138, 139, 147, 150, 155, 168, 174, 176, 180, 181, 191 and 213 are preferably used. Among these, it is preferable to use a quinophthalone compound, a condensed azo compound, or a benzimidazolone compound. Further, as the salt forming compound of yellow dye, a salt forming compound of acidic dye or a salt forming compound of basic dye is used.

  As the magenta colorant, it is preferable to use a salt-forming compound of a magenta organic pigment or a magenta dye. As magenta organic pigments, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, lake compounds of basic dyes such as rhodamine lakes, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 122, 144, 146, 147, 150, 166, 169, 177, 184, 185, 202, 206, 209, 220, 221, 254, 255, 268, 269, etc., C.I. I. Pigment violet 1, 19 and the like are preferably used. Of these, quinacridone compounds and naphthol pigments are preferably used. Specifically, naphthol AS (CI Pigment Red 269 and the like), quinacridone (CI Pigment Red 122 and the like) Carmine 6B (CI Pigment Red 57: 1) are preferable materials. A combination of a quinacridone pigment and carmine 6B, which is a monoazo pigment, is preferable because it exhibits a good magenta or red color. Further, as a salt-forming compound of a magenta dye, a salt-forming compound of a rhodamine-based acidic dye or a salt-forming compound of a rhodamine-based basic dye is preferably used.

  As the cyan colorant, it is preferable to use cyan and blue organic pigments, cyan and blue dye salt forming compounds, cyan and blue dye oil-soluble dyes, and the like. As the cyan organic pigment, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 60, 62, 66 and the like are preferably used. Among them, C.I. I. It is preferable to use a copper phthalocyanine compound such as CI Pigment Blue 15: 3. It is also preferable to use a compound derived from a triarylmethane dye in a form used in combination with the organic pigment. Furthermore, in addition to the cyan or blue organic pigment, a green pigment can be used as a complementary color for the purpose of adjusting the hue. Specific examples of the green pigment include C.I. I. Halogenated phthalocyanine compounds such as CI Pigment Green 7 and 36 are preferred.

  From the viewpoint of cost and handling, it is preferable to use organic black pigments such as carbon black and perylene black, and organic black dyes such as nigrosine dyes and azo metal complex dyes as the black colorant. As carbon black, any of various types such as furnace black, channel black, acetylene black, carbon black derived from biomass can be used. Furnace black carbon and biomass carbon are preferable because they have an effect of reducing fog (background stain on the white background) in image characteristics. As the nigrosine dye, it is preferable to use a nigrosine base that is refined by wet pulverization or the like and has a volume average particle size of 0.5 to 2 μm. Since the refined nigrosine dye has a gloss, a glossy black color can be obtained. Further, black can be obtained by using a plurality of color pigments excluding black, such as yellow, magenta, cyan, green, and violet, without using carbon black which is a black colorant.

  Furthermore, in order to obtain black with good image density and contrast, it is preferable to use a colorant in which 1 to 10 parts by mass of a blue colorant is added to 100 parts by mass of the black colorant as a black colorant. . As the blue colorant, it is preferable to use a halogen-free metal phthalocyanine blue compound, a triarylmethane compound, a dioxazine violet pigment, or the like. In addition, the phthalocyanine blue compound and the triarylmethane compound have a stable positive charging property, which is effective in obtaining good black toner particles. Specifically, C.I. I. Pigment Blue 15: 3, Victoria Pure Blue Lake Pigment (CI Pigment Blue 1), C.I. I. Pigment violet 23, C.I. I. And CI pigment violet 19. These can be used alone or in admixture of two or more.

 In addition to various organic pigments, it is preferable to use a pigment derivative as the colorant (B) from the viewpoint of color development and color reproducibility. Examples of the pigment derivative include compounds having an azo-type, phthalocyanine-type, quinacridone-type, dioxazine-type, anthraquinone-type, or perylene-type pigment as a skeleton, and one or more acidic groups or basic groups introduced into the skeleton. For example, those described in JP-B-59-40172, JP-B-63-17102, JP-B-5-9469 and the like can be used, and these can be used alone or in admixture of two or more. be able to.

  The content of the colorant (B) contained in the toner particles varies depending on the type of the binder resin (A) used, but is usually 5 to 40 parts by mass, preferably 10 to 10 parts by mass with respect to 100 parts by mass of the toner particles. 30 parts by mass.

  When a full-color image using a liquid developer is obtained, a preferable image utilizing fixability and color developability can be obtained by using four basic process colors of Y, M, C, and Bk. In addition, intermediate colors such as violet and green can be used.

(Polymer dispersant (C))
Generally, a dispersant is added to a carrier liquid in which toner particles are present to uniformly disperse the toner particles and improve development characteristics. However, the polymer dispersant (C ) May be added to the carrier liquid or may be added to the toner particles during kneading in the toner production. When added to the carrier liquid and the toner particles are dispersed, the polymer dispersant (C) is adsorbed on the binder resin portion on the toner particle surface, particularly on the polyester resin portion that exhibits excellent dispersion stability. It is inferred that Thus, the polymer dispersant (C) is preferably present in a state of being adsorbed on the surface of the toner particles or dispersed inside the toner particles.

  The polymer dispersant (C) is at least selected from an ethylenically unsaturated monomer (c-1) having an amino group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group. A copolymer obtained from an ethylenically unsaturated monomer (c-2) having one acid group and an ethylenically unsaturated monomer (c-3) having an alkyl group having a prime number of 9 to 24, A suitable polymerization method for the polymer dispersant (C) is solution polymerization of a normal acrylic resin. The ratio of the ethylenically unsaturated monomer (c-1) having an amino group (molar ratio of charged amount) is preferably 1 to 50% by mass, more preferably 5 to 5%, based on the total amount of monomers. 40% by mass, most preferably 10-30% by mass. As a ratio of the ethylenically unsaturated monomer (c-2) having at least one acid group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group, with respect to the total amount of the monomers , Preferably it is 1-50 mass%, More preferably, it is 3-40 mass%, Most preferably, it is 5-20 mass%. The ratio of the ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms is preferably 5 to 90% by mass, more preferably 20 to 80%, based on the total amount of the monomers. % By mass, most preferably 40-75% by mass.

  In accordance with the molecular weight of the intended polymer dispersant (C), an ethylenically unsaturated monomer (c-1) having an amino group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid An ethylenically unsaturated monomer (c-2) having at least one acid group selected from a group, an ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms, and any A polymer dispersant (C) can be obtained by mixing and heating a polymerization initiator, a chain transfer agent, and the like. The reaction temperature is 40 to 150 ° C, preferably 50 to 110 ° C.

(Ethylenically unsaturated monomer having an amino group (c-1))
The ethylenically unsaturated monomer (c-1) having an amino group increases the adsorption rate of the polymer dispersant (C) to the toner particles, and contributes to a stable image and excellent storage stability over a long period of time. The amino group in the ethylenically unsaturated monomer (c-1) having an amino group is not particularly limited, but is preferably a secondary amino group or a tertiary amino group, and more preferably a tertiary amino group. . The amino group here does not include an amino group constituting an amide bond. For example, in alkyl (meth) acrylamides which are examples of an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms, the effect of the ethylenically unsaturated monomer (c-1) having an amino group is exerted. Can't get. Among the ethylenically unsaturated monomers (c-1) having an amino group, examples of the ethylenically unsaturated monomer having a tertiary amino group include N, N-dimethylaminoethyl (meth) acrylate, N N, N-dialkylamino group-containing (meth) acrylic acid esters such as N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate; N, N such as N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide -Dialkylamino group-containing (meth) acrylamides; Dimethylamino Styrene, diethylamino styrene; and the like are.

  Examples of the ethylenically unsaturated monomer having a secondary amino group include tert-butylaminoethyl (meth) acrylate, tetramethylpiperidinyl (meth) acrylate, and the like.

  Among these, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and the like are preferable from the viewpoint of dispersibility. Two or more ethylenically unsaturated monomers (c-1) having an amino group may be used in combination.

(An ethylenically unsaturated monomer (c-2) having at least one acid group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group)
Monomers having carboxylic acid groups include acrylic acid, acrylic acid dimer, methacrylic acid, crotonic acid, itaconic acid, itaconic anhydride, maleic acid, maleic anhydride, fumaric acid, citraconic acid, 2- (meth) acryloyloxy Ethyl succinic acid, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxypropyl phthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, 2- (meth) acryloyloxypropyl hexahydro Examples include ethylenically unsaturated carboxylic acids such as phthalate, ethylene oxide-modified succinic acid (meth) acrylate, β-carboxyethyl (meth) acrylate, or ω-carboxypolycaprolactone (meth) acrylate, or salts thereof. In terms of methacryl Acid, 2- (meth) acryloyloxyethyl succinic acid, and 2- (meth) acryloyloxyethyl hexahydrophthalate are preferable. These monomers can be used alone or in combination of two or more.

  Examples of the resin having a sulfonic acid group include a vinyl polymer containing a monomer having a sulfonic acid group as a polymerization component. Examples of the monomer having a sulfonic acid group include 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, allylsulfonic acid, Examples include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, 2-sulfoethyl methacrylate, 4-sulfobutyl methacrylate, and the like.

The phosphate group contained in the resin having a phosphate group may be a monovalent phosphate group represented by the general formula (3) or a divalent phosphate group represented by the general formula (4). Good.
General formula (3):

Formula (4):

As the monomer having a phosphoric acid group, for example, a monomer represented by the following general formula (5) represented by ethylene glycol methacrylate phosphate, propylene glycol methacrylate phosphate, ethylene glycol acrylate phosphate, propylene glycol acrylate phosphate Can be mentioned.
General formula (5):
(In general formula (5), R ³ represents hydrogen or a methyl group, R ⁴ represents an alkylene group, and u represents an integer of 1 to 20.)

Although the specific example of the monomer which has a phosphoric acid group is shown below, it is not restricted to this.

  These monomers having a phosphoric acid group can be produced by the methods described in JP-B-50-22536 and JP-A-58-128393. Commercially available products include Phosmer M, Phosmer CL, Phosmer PE, Phosmer MH (made by Unichemical Co., Ltd.), Light Ester P-1M (made by Kyoeisha Chemical Co., Ltd.), JAMP-514 (made by Johoku Chemical Industry Co., Ltd.), KAYAMER PM-2, KAYAMER PM-21 (manufactured by Nippon Kayaku Co., Ltd.) and the like.

  Examples of the monomer having a boronic acid group include (4-vinylphenyl) boronic acid, 4-ethenylphenylboronic acid, 4-vinylphenylboronic acid, 4-vinylphenylboronic acid, p-vinylphenylboronic acid, and 3-acrylamide. And phenylboronic acid.

(Ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms (c-3))
In the ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms, the alkyl group having 9 to 24 carbon atoms enhances solubility in the carrier liquid (D), and toner particles in wet pulverization In addition, when stored for a long period of time, aggregation of toner particles and increase in viscosity of the liquid developer are suppressed, and an excellent storage stability effect is exhibited. When the alkyl group has 9 or more carbon atoms, the solubility in the carrier liquid (D) is high, and the dispersion stability and storage stability of the toner particles are enhanced. When the alkyl group has 24 or less carbon atoms, when the liquid developer is fixed to the substrate, the alkyl group does not hinder the contact and coalescence of the toner particles, and the fixing property does not deteriorate. Furthermore, the chargeability of the toner particles is increased, the toner particles are easily transferred to the substrate, and a sufficient image density can be obtained.

  Moreover, the C9-24 alkyl group may have a substituent, and examples of the substituent include aromatic hydrocarbon groups such as a phenyl group, a naphthyl group, and a biphenyl group. In addition, the ethylenically unsaturated monomer (c-4) shown by General formula (1) mentioned later is not contained in the ethylenically unsaturated monomer which has a C9-C24 alkyl group. The ethylenically unsaturated monomer represented by the general formula (5) has a hydrocarbon group having 1 to 22 carbon atoms, but the ethylenically unsaturated monomer represented by the general formula (5). Depending on the body, the effect of the ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms cannot be obtained.

Examples of the ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms include nonyl (meth) acrylate, 8-methylnonyl (meth) acrylate, 2-methylnonyl (meth) acrylate, decyl ( (Meth) acrylate, 2-methyldecyl (meth) acrylate, undecyl (meth) acrylate, 2-methylundecyl (meth) acrylate, 9-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl (meth) ) Acrylate, 11-methyldodecyl (meth) acrylate, tridecyl (meth) acrylate, 2-methyltridecyl (meth) acrylate, tetradecyl (meth) acrylate, 2-methyltetradecyl (meth) acrylate, pentadecyl (meth) acrylate, -Methylpentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 2-methylheptadecyl (meth) acrylate, octadecyl (meth) acrylate, 2-methyl Octadecyl (meth) acrylate, nonadecyl (meth) acrylate, 2-methylnonadecyl (meth) acrylate, icosyl (meth) acrylate, heicosyl (meth) acrylate, docosyl (meth) acrylate, tertiary butylcyclohexyl (meth) acrylate, dicyclopenta Alkyl having an alkyl group of 9 to 24 carbon atoms such as nyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, etc. (Meth) (meth) acrylates such as acrylate;
N-nonyl (meth) acrylamide, N-decyl (meth) acrylamide, N-undecyl (meth) acrylamide, N- (1-methylundecyl) (meth) acrylamide, N-dodecyl (meth) acrylamide, N, N- Didodecyl (meth) acrylamide, N-tridecyl (meth) acrylamide, N-tetradecyl (meth) acrylamide, N-hexadecyl (meth) acrylamide, N, N-dihexadecyl (meth) acrylamide, N, N-dioctadecyl (meth) acrylamide Alkyl (meth) acrylamides having an alkyl group having 9 to 24 carbon atoms, such as N-icosyl (meth) acrylamide, N-henicosyl (meth) acrylamide, and N-docodecyl (meth) acrylamide;
4-nonylphenyl (meth) acrylate, 4′-decyl-4-biphenylyl (meth) acrylate, 3-pentadecylphenyl (meth) acrylate, N- (10-phenyldecyl) (meth) acrylamide, N- (4- Dodecylphenyl) (meth) acrylamide, N- [2- (1-naphthyl) ethyl] -N-dodecyl (meth) acrylamide, N- [4- (1-pyrenyl) butyl] -N-dodecyl (meth) acrylamide, (Meth) acrylates and (meth) acrylamides having an aromatic ring such as N-octadecyl-N- [2- (1-naphthyl) ethyl] (meth) acrylamide and an alkyl group having 9 to 24 carbon atoms;
1-undecene, 1-dodecene, 2-dodecene, 1-tridecene, 2-tridecene, 1-tetradecene, 2-tetradecene, 4-tetradecene, 1-pentadecene, 2-pentadecene, 4-pentadecene, 1-hexadecene, 2- C9-24 alkyl such as hexadecene, 4-hexadecene, 1-heptadecene, 2-heptadecene, 4-heptadecene, 1-octadecene, 2-octadecene, 4-octadecene, 1-docosene, 2-docosene, 4-docosene, etc. And α-olefins having a group;

  Among these, from the viewpoint of dispersibility, (meth) acrylates such as alkyl (meth) acrylate having an alkyl group having 9 to 24 carbon atoms are preferable. Examples of the alkyl group having 9 to 24 carbon atoms include a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, and a linear alkyl group or a branched alkyl group is preferable. Two or more types of ethylenically unsaturated monomers having an alkyl group having 9 to 24 carbon atoms may be used in combination.

(Ethylenically unsaturated monomer (c-4) represented by general formula (1))
Among the polymeric dispersants (C), the ethylenically unsaturated monomer (c-4) represented by the general formula (1) is effective in improving the fixability and can be copolymerized. Is the body. By including the ethylenically unsaturated monomer represented by the general formula (1), the compatibility with the binder resin (A) is improved, and in the fixing process, the melting of the toner particles is increased, so that The fixability of is improved. In addition, a cold offset phenomenon in which insufficiently melted toner particles adhere to the thermocompression roller and transfer to the next paper is less likely to occur. In addition, the dispersion stability of the toner particles is improved by having the ethylenically unsaturated monomer (c-4) represented by the general formula (1). Although the detailed factor is unknown, the ethylenically unsaturated monomer (c-4) represented by the general formula (1), which is a hydrophilic group, facilitates ionization of ions formed from an amine and an acid, resulting in charge repulsion. It is thought that the power is further improved. The ethylenically unsaturated monomer (c-4) represented by the general formula (1) is obtained by, for example, subjecting ethylene oxide to ring-opening polymerization with alkyl alcohol, and then converting the resulting reaction product with methyl (meth) acrylate. It is obtained by transesterification or by reacting with (meth) acrylic acid chloride.

General formula (1)
CH ₂ = C (R ¹ ) COO (AO) _n R ²
(In the general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and n represents 1 to 200. And A represents an alkylene group having 2 to 4 carbon atoms.)

  In the said General formula (1), an alkylene oxide group (AO) is a C2-C4 alkylene oxide group, for example, an ethylene oxide group, a propylene oxide group, or a butylene oxide group is mentioned. Moreover, the alkylene oxide group from which carbon number differs may exist in the same monomer.

The number (n) of alkylene oxide groups is an integer of 1 to 200, preferably an integer of 1 to 30. When it is 200 or less, sufficient compatibility with the ethylenically unsaturated monomer (c-2) having an alkyl group having 9 to 24 carbon atoms in the molecule can be obtained. R ² is hydrogen or a hydrocarbon group having 1 to 22 carbon atoms. When the number of carbon atoms is 22 or less, raw materials are easily available and practical. As the hydrocarbon group having 1 to 22 carbon atoms, a substituted or unsubstituted group can be selected, an unsubstituted group is preferable, and an unsubstituted alkyl group is preferable. As the unsubstituted alkyl group, those having a branch and those having no branch can be used. Two or more types of ethylenically unsaturated monomers (c-4) represented by the general formula (1) may be used in combination. R ² is more preferably hydrogen or a hydrocarbon group having 1 to 18 carbon atoms.

  Specific examples of the compound having an alkylene oxide chain include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, and poly (ethylene glycol-propylene glycol) mono (meta). ) Acrylate, poly (ethylene glycol-tetramethylene glycol) mono (meth) acrylate, poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate, polyethylene glycol mono (meth) acrylate monomethyl ether, polyethylene glycol mono (meth) acrylate Monobutyl ether, polyethylene glycol mono (meth) acrylate monooctyl ether, polyethylene glycol mono (me ) Acrylate monobenzyl ether, polyethylene glycol mono (meth) acrylate monophenyl ether, polyethylene glycol mono (meth) acrylate monodecyl ether, polyethylene glycol mono (meth) acrylate monododecyl ether, polyethylene glycol mono (meth) acrylate monohexadecyl ether , Polyethylene glycol mono (meth) acrylate monooctadecyl ether, poly (ethylene glycol-propylene glycol) mono (meth) acrylate octyl ether, poly (ethylene glycol-propylene glycol) mono (meth) acrylate octadecyl ether, poly (ethylene glycol-propylene Glycol) mono (meth) acrylate nonylphenyl ether etc. It is below. Two or more of these may be used in combination.

  When the polymer dispersant (C) contains the ethylenically unsaturated monomer (c-4) represented by the general formula (1), the blending ratio is 1 to 40 mass with respect to the total amount of the monomer. %, And more preferably 10 to 30% by mass.

(Other copolymerizable polymerizable monomers)
Other unsaturated compounds that may be included as polymerizable monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate. , Isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, etc. (Meth) acrylates such as alkyl (meth) acrylates having 1 to 8 alkyl groups;
N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-neopentyl (meth) acrylamide, N-hexyl (meth) acrylamide, (Meth) acrylamides such as Nn-heptyl (meth) acrylamide and N- (6-methylheptyl) (meth) acrylamide;
1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 4-ethyl-2-hexene, 1-heptene, 2-heptene, 1-octene, 2-octene, 1- Examples thereof include α-olefins having an alkyl group having 1 to 8 carbon atoms such as nonene, 2-nonene, 1-decene and 2-decene.

  Furthermore, cyclic alkyl (meth) acrylates such as cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate and dicyclopentenyloxyethyl (meth) acrylate; aromatic rings such as benzyl (meth) acrylate (meth) Acrylates: Vinyl such as styrene, α-methylstyrene, vinyl acetate, vinyl (meth) acrylate, or allyl (meth) acrylate can be exemplified. Unsaturated compounds other than those described above can also be used as long as they do not affect the physical properties.

  The acid value of the polymer dispersant (C) is preferably 5 to 40 mgKOH / g. More preferably, it is 5-20 mgKOH / g. When the acid value is 5 mgKOH / g or more, the ionic concentration for repelling the charge of the polymer dispersant (C) adsorbed on the toner particles is sufficient, and the pulverization property by wet pulverization is improved. Furthermore, during storage over a long period of time, aggregation of toner particles is suppressed and storage stability is improved. When the acid value is 40 mgKOH / g or less, the chargeability of the toner particles becomes high, the transfer to the substrate is good, and a sufficient image density can be obtained. The acid value can be measured using a “potentiometric automatic titrator AT-610” manufactured by Kyoto Electronics Industry Co., Ltd.

  The amine value of the polymer dispersant (C) is preferably 5 to 150 mgKOH / g. More preferably, it is 30-100 mgKOH / g. When the amine value is 5 mgKOH / g or more, the polymer dispersant (C) is highly adsorbed on the toner particles, and the pulverization property by wet pulverization is improved. Further, during storage for a long period of time, aggregation of toner particles is prevented, and a liquid developer having excellent storage stability can be obtained. When the amine value is 150 mgKOH / g or less, the chargeability of the toner particles to which the polymer dispersant (C) is adsorbed becomes high, the transfer of the toner particles to the substrate is good, and a sufficient image density can be obtained. it can. Furthermore, the solubility in the carrier liquid (D) is increased, and the grindability is improved. The amine value of the polymer dispersant (C) is the total amine value (mgKOH / g) measured according to the method of ASTM D2074.

  The weight average molecular weight (Mw) of the polymer dispersant (C) of the present invention is preferably 500 to 40,000 in terms of molecular weight measured by gel permeation chromatography (GPC), preferably 2,000 to More preferably, it is 30,000. When the weight average molecular weight (Mw) is 500 or more, the pulverization property and dispersion stability of the toner particles are improved, and a liquid developer having excellent storage stability can be obtained. When it is 40,000 or less, good fixability can be obtained. Further, a liquid developer having high chargeability of toner particles, sufficient image density, and excellent color developability can be obtained. The weight average molecular weight (Mw) can be measured by the method described above.

  The polymer dispersant (C) can be added in an amount of preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the liquid developer. More preferably, it is the range of 0.5-5 mass parts. When the amount is 0.1 part by mass or more, the dispersibility and pulverization properties of the toner particles are improved, and the storage stability is improved. When the addition amount is 10 parts by mass or less, the chargeability of the toner particles is increased, so that a sufficient image density can be obtained and the fixability is also improved. When the toner particles contain the polymer dispersant (C), the above range is a range including the amount of the polymer dispersant (C) contained in the toner particles.

(Other dispersants)
As the dispersant, in addition to the polymer dispersant (C) used in the present invention, a dispersant conventionally used in a liquid developer may be used. Specifically, fatty acid metal salts such as cobalt naphthenate, zinc naphthenate, cobalt octylate and zirconium octylate, titanate coupling agents of organic titanates such as lecithin and titanium chelates, alkoxy titanium polymers, polyhydroxy titanium carboxylates Examples include compounds, titanium alkoxides, succinimide compounds, polyimine compounds, fluorine-containing silane compounds, and pyrrolidone compounds. Among them, a titanium alkoxide, a succinimide compound, a fluorine-containing silane compound, a pyrrolidone-based compound, and the like may be mixed and used in an amount of 5 parts by mass or less with respect to 100 parts by mass of the liquid developer.

(Polymerization initiator)
Although it does not specifically limit as a polymerization initiator used by superposition | polymerization of a polymer dispersing agent (C), For example, an azo type compound and an organic peroxide can be used. In the polymerization, 0.001 to 5 parts by mass of a polymerization initiator can be arbitrarily used with respect to 100 parts by mass of all monomers.

  Examples of the azo compounds include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) ), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2 ′-[2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxy Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  These polymerization initiators can be used alone or in combination of two or more.

(Chain transfer agent)
As the chain transfer agent, thiol compounds such as mercaptan-based, thioglycol-based, β-mercaptopropionic acid-based, rosin-based compounds having allylic hydrogen, terpene-based compounds, and the like can be used. When using a chain transfer agent, the addition amount is 0.01 to 10.0 parts by mass, preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of all monomers.

(Polymerization solvent)
In the synthesis of the polymer dispersant (C), a known solvent is preferably used. However, when the polymer dispersant (C) is used as a liquid developer, the polymer dispersant (C) can be taken out in a state dissolved in the solvent of the carrier liquid (D) used in the liquid developer, or It is preferable that it can be taken out as a solid. When the polymer dispersant (C) is added when the toner particles are wet-dispersed in the carrier liquid (D), the polymer dispersant (C) is preferably dissolved in the carrier liquid (D). In the case where the molecular dispersant (C) is used by adding it to the toner particles when preparing the toner particles, the polymer dispersant (C) is preferably a solid. There are the following three methods for obtaining the polymer dispersant (C) dissolved in the carrier liquid (D). As a first method, the carrier liquid (D) used in the liquid developing toner is polymerized using a synthetic solvent. As a second method, polymerization is performed in a solvent that can be replaced with the carrier liquid (D), and then the carrier liquid (D) is added, and only the solvent used for the polymerization is distilled off. As a third method, polymerization is performed in a mixed solution of a solvent that can be replaced with the carrier liquid (D) and the carrier liquid (D), and then only the solvent other than the carrier liquid (D) is distilled off. Therefore, as the polymerization initiator, it is preferable to use a solvent that can be replaced with the carrier liquid (D) used for the liquid developer after the synthesis to the polymer dispersant (C) or a solvent that can be distilled off.

  As a solvent that can be solvent-substituted for the carrier liquid (D), a solvent having a boiling point lower than that of the carrier liquid (D) is preferable. For example, ethyl acetate, n-propyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, ethanol, propanol, butanol and the like are used. Two or more kinds of these polymerization solvents may be mixed and used. Among these, n-propyl acetate or toluene is particularly preferable from the viewpoints of polymerization temperature, simplicity of solvent evaporation, solvent polarity, and the like. In order to take it out as a solid, the solvent is distilled off after the polymerization of the polymer dispersant (C). The solvent that can be distilled off is not particularly limited, but a solvent that can be easily distilled off as described above is preferable.

(Carrier liquid (D))
The carrier liquid (D) used for the liquid developer is preferably an aliphatic hydrocarbon. Examples of the aliphatic hydrocarbon include linear paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and the like. Among these, paraffinic hydrocarbons with very little residual aromatic hydrocarbon are preferable. Further, those having lipophilic properties, chemically stable and insulating properties are preferred. Further, the carrier liquid is preferably chemically inert with respect to a substance or apparatus used in the image forming apparatus, in particular, a member for a development process such as a photosensitive member and its peripheral part.

  The dry point in the distillation range of the carrier liquid (D) is preferably in the range of 230 to 360 ° C. Especially preferably, it is the range of 240-320 degreeC. When the temperature is 230 ° C. or higher, the liquid developer does not dry at room temperature, and the compatibility with the polymer dispersant (C) is high, and good storage stability can be maintained. Further, since no solid matter is deposited, no sticking matter is generated on the developing roller or the regulating blade around the photosensitive member, and image contamination does not occur. When the temperature is 360 ° C. or lower, the carrier liquid (D) can be easily removed, so that excellent fixability can be obtained without hindering the melting and coalescence of the toner particles containing the polymer dispersant (C). Here, the dry point in the distillation range is determined by the method defined by ASTM D86, ASTM D1078, and JIS K2254.

  The carrier liquid (D) preferably has an aniline point (JIS K2256) of 75 to 100 ° C. More preferably, it is the range of 80-95 degreeC. When the aniline point is 75 ° C. or higher, the dissolving ability as a solvent is low, and the carrier liquid (D) does not dissolve the binder resin (A). Therefore, the toner particles exist stably, and the dispersion stability. Is good. Further, it is possible to prevent the occurrence of image contamination, such as the carrier liquid (D) being colored and soiling a substrate such as paper. When the aniline point is 105 ° C. or lower, a liquid developer having high compatibility with the polymer dispersant (C), improved pulverization and dispersion stability of toner particles, and excellent storage stability can be obtained.

  Furthermore, it is preferable to use a carrier liquid (D) having a Kauri-butanol value (KB value: ASTM D1133) of 40 or less. More preferably, it is the range of 20-30. When the Kauri-butanol value is 40 or less, the dissolving ability as a solvent is low, and the carrier liquid (D) does not dissolve the toner particles, so that the storage stability of the toner particles becomes high.

Specifically describing the insulating property of the carrier liquid (D), the dielectric constant is 10 or less, preferably 1 to 5, and more preferably 2 to 3. At the same time, the electric resistivity of the carrier liquid (D) is preferably 10 ⁹ Ω · cm or more, more preferably 10 ¹⁰ Ω · cm or more, and particularly preferably 10 ¹¹ to 10 ¹⁶ Ω · cm. Here, the electrical resistivity can be determined by combining a universal electrometer MMA-II-17D manufactured by Kawaguchi Electric Manufacturing Co., Ltd. and a liquid electrode LP-05. When the electrical resistivity is 10 ⁹ Ω · cm or more, the chargeability of the toner particles becomes high, and a sufficient image density can be obtained, and color reproducibility and color developability are improved.

Further, the carrier liquid (D) preferably has a kinematic viscosity (ASTM D445) in the range of 1 to 25 mm ² / s. Especially preferably, it is the range of 3-15 mm < ² > / s. This range is preferable in that the charged particles can be moved during the phenomenon, and the carrier liquid can be easily removed from the medium on which the image is formed in the fixing step. When the kinematic viscosity is 1 mm ² / s or more, the viscosity of the liquid developer increases, so that the transfer property to the developing roller is high, and a sufficient image density can be obtained. Further, when the kinematic viscosity is 25 mm ² / s or less, the fluidity of the toner particles is improved and electrophoresis tends to occur, so that a sufficient image density can be obtained.

 In the present invention, when an aliphatic hydrocarbon is used as the carrier liquid (D), the ratio of primary carbon is 55% or more with respect to the total number of primary to tertiary carbons of the aliphatic hydrocarbon. Also preferred are those in which the ratio of secondary carbon is 30% or less. Aliphatic hydrocarbons with a primary carbon content of 55% or more and secondary carbon content of 30% or less are excellent in oxidation resistance to ozone generated by the charging device, and deteriorate in image quality and continuous printing stability. It is possible to obtain a liquid developer that does not occur.

  Specific examples of preferred carrier liquid (D) include trade names “Shellsol ™” (manufactured by Shell Chemicals), “IP Solvent 2028” (manufactured by Idemitsu Kosan Co., Ltd.), “Isopar M”, “Isopar L” (Exxon). Mention may be made of branched paraffin solvent mixtures such as “Exor D40”, “Exor D110”, “Exor D130” (Exxsol ™) (Exxon Mobil Corporation), such as branched paraffin solvent mixtures such as Mobil Corporation. In particular, isoparaffinic hydrocarbons such as “Shellsol TM”, “IP Solvent 2028”, “Isopar M” are preferably used.

(Other additives)
(Pigment dispersant)
As the pigment dispersant internally added to the toner particles, Solsperse 24000SC, Solsperse 32000 (manufactured by Lubrizol), which is a polyamine-based resin-type dispersant, Addisper PB821 (manufactured by Ajinomoto Fine Techno Co.); resin type of acrylic copolymer Dispersant BYK-116 (manufactured by Big Chemie) or the like can be used. In particular, when producing via a colored master batch having a high pigment concentration, it is preferable to add at the time of producing the master batch. The addition amount of the pigment dispersant is preferably 3 parts by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the colorant (B) from the viewpoint of improving the dispersibility of the toner particles. Further, from the viewpoint of improving the grindability and productivity of the toner particles, the amount is preferably 40 parts by mass or less, more preferably 30 parts by mass or less with respect to 100 parts by mass of the colorant (B).

(Charge control agent)
The toner particles in the liquid developer may contain a colorless or light-color charge control agent as long as the hue does not hinder the hue. As the charge control agent, a positive charge control agent or a negative charge control agent is used according to the polarity of the electrostatic image on the electrostatic latent image carrier to be developed. In the liquid developer, the toner particles are preferably positively charged, and a positive charge control agent is usually used.

  As the positive charge control agent, quaternary ammonium salt compounds (for example, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate), quaternary ammonium salt organotin oxide (for example, dioctyltin oxide), diorganotin borate (For example, dibutyltin borate), an electron donating substance such as a polymer having an amino group, or the like can be used alone or in combination of two or more. Triarylmethane dyes can also be used as positive charge control agents. Furthermore, instead of using the charge control agent, a resin charge control agent can be used. Examples of the resin charge control agent include a copolymer of acryloylamino-2-methyl-1-propanesulfonic acid and a vinyl monomer such as styrene or acrylate ester. Further, the resin charge control agent is usually added in an amount of preferably 1.0 to 20 parts by mass, more preferably 2.0 to 8 parts by mass with respect to 100 parts by mass of the binder resin (A).

(Production method)
A method for producing the liquid developer will be described. The liquid developer is preferably obtained, for example, through the following five processes.

(1) Preparation of Colored Master Batch for Toner Particles The binder resin (A) and the colorant (B) are heated in such a ratio that the concentration of the colorant (B) in the master batch is 10 to 60 parts by mass. Kneading is performed using a roll or the like, and after cooling, coarse crushing is performed to obtain a colored master batch. In addition to the binder resin (A) and the colorant (B), a pigment dispersant, a dye derivative, and the like can also be added.

(2) Preparation of toner particle chips (dilution of colored master batch)
The colored masterbatch obtained in (1) and the binder resin (A) are mixed with a mixer such as a super mixer, preliminarily dispersed, and then melt-kneaded, whereby the colored masterbatch is bound to the binder resin (A). Diluted in and developed to obtain a chip for toner particles. At the time of performing preliminary dispersion and melt-kneading here, a pigment dispersant, a polymer dispersant (C), a charge control agent, a release agent and the like may be added. Further, it is preferable that the toner particle chip has a particle size of 10 mm or less by rough crushing with a hammer mill, a sample mill or the like. In addition, the steps (1) and (2) can be integrated. In that case, all steps during the preliminary dispersion in the step (2) without passing through the coloring masterbatch step (1). The material may be charged to produce a toner particle chip. As the melt-kneading, a known kneader such as a pressure kneader, a uniaxial or biaxial extruder can be used.

(3) Dry pulverization of toner particles The toner particle chip obtained in (2) is pulverized into toner particles. For fine pulverization, it is usually preferable to use a jet airflow pulverizer such as a jet mill or a mechanical pulverizer such as a turbo mill.

(4) Wet pulverization of toner particles The dry pulverized toner particles obtained in (3) are developed in a solvent having the same composition as that of the carrier liquid (D), and the average particle size is measured using a wet pulverizer (disperser). Is pulverized to a range of 0.5 to 4 μm, preferably 1 to 3 μm. At this time, it is effective to add a polymer dispersant (C) having a function of adsorbing the toner particles. Through the wet pulverization and dispersion process, the polymer dispersant (C) is adsorbed in the toner particles and is also stabilized in terms of charging. When performing wet pulverization (dispersion), it is desirable to cool so that the temperature during pulverization does not exceed 50 ° C. When the temperature is 50 ° C. or lower, the particle size distribution can be controlled without causing fusion of the toner particles.

  As a wet pulverizer that can be used for wet pulverization of toner particles, a pulverization medium is used, and examples thereof include a container drive medium mill and a medium stirring mill. Examples of the container drive medium mill include a rolling ball mill and a planetary ball mill. Examples of the medium agitation mill include a stirring tank mill and a flow tank mill (horizontal type, vertical type). Any of the above is useful as a wet pulverizer, but it is preferable to use a medium stirring mill from the viewpoints of pulverizing ability, control of particle size distribution, and the like. Furthermore, it is possible to use a wet pulverizer classified as a horizontal circulation tank mill, which is sealed and horizontal, and is filled with microbeads and used as a medium (medium), in order to perform precise wet pulverization and dispersion. Is preferable. Specific examples include Dino Mill manufactured by Shinmaru Enterprises. In the horizontal type wet pulverizer, since the dispersion medium is hardly affected by gravity, a uniform distribution close to ideal can be obtained in the pulverizer.

  In the wet pulverizer, the major factors that determine the pulverization properties are the type of pulverization media, the particle size of the pulverization media, the filling rate of the dispersion media in the pulverizer, the type of agitator disk, the concentration of the sample to be pulverized, the solvent Types are listed. Among these, the type of pulverized media and the particle size of the media greatly contribute to pulverization.

The types of grinding media include glass beads (SiO ₂ 70-80%, NaO 12-16%, etc.), zircon beads (ZrO ₂ 69%), depending on the viscosity, specific gravity, required particle size of grinding and dispersion, and the like. , SiO2 31%), zirconia beads (ZrO ₂ 95% or more), alumina (Al ₂ O ₃ 90% or more), titania (TiO ₂ 77.7%, Al ₂ O ₃ 17.4%), etc. can be used. Among them, it is preferable to use zirconia beads or zircon beads in order to obtain good grindability. Moreover, although the particle diameter (diameter) of a grinding | pulverization media can be used in the range of 0.1 mm-3.0 mm, it is preferable that it is the range of 0.3-1.4 mm especially. When it is 0.1 mm or more, the load in the pulverizer is reduced, the toner particles are prevented from melting due to heat generation, and good pulverizability is obtained. When the thickness is 3.0 mm or less, sufficient pulverization can be performed. The filling rate of the dispersion medium is preferably 40 to 85% by mass.

(5) Purification of liquid developer The toner particles (containing at least the binder resin (A) and the colorant (B)) obtained by the wet pulverization obtained in (4), the carrier liquid (D), and the dispersant are used. A carrier liquid (D) and, if necessary, a dispersant are further added to and mixed with the contained material, and the liquid developer is purified while controlling the concentration of toner particles. The polymer dispersant (C) may be added in any of the steps (1) to (5), but should be added to the material obtained in the step (4) together with the carrier liquid (D) for preparation. Thus, a liquid developer in which toner particles are stably dispersed can be obtained.

(Liquid developer properties)
The toner particles preferably have an average particle diameter (D50) of 0.5 to 4 μm, more preferably 1 to 3 μm. In the present invention, the particle size is measured using a laser diffraction scattering particle size analyzer Microtrac HRA manufactured by Nikkiso Co., Ltd., and the average particle size (D50) is a cumulative 50 percent diameter value.

  Further, development for obtaining color developability is that 50% by volume or less of toner particles having a particle size of 2 μm or less with respect to all the toner particles and 35% by volume or less of toner particles having a particle size of 5 μm or more are contained. More preferable in terms of characteristics. When the toner particles having a particle size of 2 μm or less are 50% by volume or less, the polymer dispersant (C) is highly adsorbed to the toner particles, and excellent storage stability is obtained. Furthermore, the pulverization property becomes high in wet pulverization of toner particles, and the viscosity control of the liquid developer becomes easy. When the toner particles having a particle diameter of 5 μm or more are 35% by volume or less, there are effects that a sufficient image density can be obtained and color development and color reproducibility are improved.

  The concentration of the toner particles in the liquid developer is preferably 10 to 30% by mass with respect to 100% by mass of the liquid developer. More preferably, it is 12-25 mass%. When the content is 10% by mass or more, the carrier liquid (D) can be easily removed, and the fixability of the toner particles is improved. When the content is 30% by mass or less, the viscosity of the liquid developer is lowered, the mobility of the toner particles is improved, and a sufficient image density is obtained. Furthermore, toner particle aggregation is weakened and storage stability is increased.

The adsorption rate of the polymeric dispersant (C) to the toner particles in the liquid developer is defined as: adsorption rate = (amount of dispersant adsorbed on the toner particles) / (dispersant content in the liquid toner) It can be measured as follows. 10 g of liquid developer is weighed and centrifuged at 19,000 rpm for 20 minutes using a centrifuge CR22H manufactured by Hitachi Koki Co., Ltd. 1 g of the separated supernatant solution is weighed, and the carrier liquid (D) is volatilized in an oven at 180 ° C. for 1 hour. The residual polymer dispersant (C) is weighed, and the adsorption rate to the toner particles is calculated from the obtained value. The adsorption rate is preferably 50% or more. More preferably, it is 70% or more. If it exceeds 50%, the dispersion stability of the toner particles becomes high, and the average particle diameter and viscosity of the liquid developer do not increase even during long-term storage, and stable color development and color reproducibility can be obtained. . In order for the adsorption rate of the polymer dispersant (C) to the toner particles to be 50% or more, the amine value of the polymer dispersant (C), the carbon number of the alkyl group of the ethylenically unsaturated monomer, the acid group ethylenically unsaturated monomer having a (c-2) of the acid groups of the type and R ^3, the carbon number of R ^4, further, may control the respective mass ratios.

The viscosity (η) of the liquid developer of the embodiment is preferably 5 to 180 mPa · s, and the electrical resistivity of the liquid developer is preferably 10 ¹⁰ to 10 ¹⁵ Ω · cm. The viscosity (η) of the liquid developer can be measured using, for example, an E-type viscometer TV-22 manufactured by Toki Sangyo Co., Ltd. When the viscosity (η) is 5 mPa · s or more, the fineness of the image after development is improved, and when it is 180 mPa · s or less, the mobility of toner particles during development is increased and high-speed development is possible. There is an effect that the image density can be obtained. The electrical resistivity can be measured in the same manner as in the carrier liquid measurement method described above. When it is 10 ¹⁰ Ω · cm or more, the electrostatic latent image on the photosensitive member can be easily held.

(Development of liquid developer)
A development process that can be preferably used for forming a printed product that is a development product of a liquid developer is to supply the liquid developer to a development roller made of a conductive rubber, and to remove static electricity before transfer using an amorphous silicon photoconductor exposed to LED. The development is preferably performed via an intermediate transfer member. The photoreceptor preferably has a surface potential of +450 to 550 V, a residual potential of +50 V or less, and the bias applied to the developing roller is preferably in the range of +250 to 450 V.

  The printing substrate to be printed with the liquid developer is not particularly limited, and examples include generally used fine paper, coated paper, PET sheet, and PP sheet. As the coated paper, all widely used coated papers that have been used for various purposes in the past can be used. Specifically, for example, fine coated paper, coated paper, art paper, matte coated paper, cast coated paper. These thicknesses and shapes are not limited at all. These may have a smooth surface of the printing substrate, may have irregularities, or may be transparent, translucent, or opaque. Further, two or more of these printing substrates may be bonded to each other. Furthermore, a peeling adhesive layer or the like may be provided on the opposite side of the printing surface, and an adhesive layer or the like may be provided on the printing surface after printing.

  Although the printed matter printed with the liquid developer is not particularly limited, it is used for general commercial use, paper package, packaging film, seal, label use and the like. For example, in general commercial use, catalogs using high-quality paper, coated paper, etc., books or forms such as magazines, in paper container packages, packaging containers or outer boxes using coated paper, cardboard, etc., in packaging films , Flexible packaging containers using PET sheets, PP sheets and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the embodiment of the present invention is not limited to these examples. In the following, “part” means “part by mass” unless otherwise specified.

  Moreover, in the Example, it carried out using the material described below.

(Synthesis example of binder resin 1)
Into a flask equipped with a reflux condenser, distillation, etc., a nitrogen gas introduction tube, a thermometer, and a stirrer, the polyhydric alcohol and polybasic acid shown in Table 1 and 2 parts of dibutyltin oxide as a catalyst were added and stirred. While introducing nitrogen gas, the mixture was heated to 200 ° C. and reacted for 4 hours while maintaining the temperature of the reaction system. Furthermore, it was made to react under reduced pressure for 1 hour. The pressure was returned to normal pressure, the temperature of the reaction system was lowered to 100 ° C. or lower, and polycondensation was stopped to obtain a binder resin 1 which was a polyester resin.

  Among the compositions described in Table 1, the bisphenol A propylene oxide adduct represents a compound in which R = propylene group and x = y = 2 in the chemical formula (1). The bisphenol A ethylene oxide adduct represents a compound in which R = ethylene group and x = y = 2 in the chemical formula (1).

(Synthesis example of binder resin 2)
The obtained binder resin 1 was put in an equal amount of toluene and heated to be dissolved. Nitrogen gas was introduced with stirring, and the mixture was further heated to the boiling point of toluene, and 2 mixed solutions containing styrene monomers, acrylic esters, and di-t-butyl peroxide as a polymerization initiator shown in Table 2 were obtained. Solution polymerization was carried out while dropping over time. After completion of the dropwise addition, the reaction was further continued at the boiling point of toluene for 2 hours, and 1 part of di-t-butyl peroxide was added to terminate the polymerization. Next, it heated up to 180 degreeC and toluene was removed, and the binder resin 2 containing a polyester resin and a styrene-acryl copolymer resin was obtained.

(Synthesis example of binder resins 3 and 4)
Synthesis was performed in the same manner as in Synthesis Example 1 except that the raw materials, preparation amounts, and reaction conditions described in Table 3 were used, and binder resins 3 and 4 were obtained.

Table 4 shows the physical property values of the obtained binder resins 1 to 4.

(Synthesis Example of Polymer Dispersant 1)
Into a reaction vessel equipped with a nitrogen gas introduction tube, a thermometer, a condenser, and a stirrer, 90.1 parts of Exol D110 (naphthenic hydrocarbon solvent, manufactured by ExxonMobil) was charged and replaced with nitrogen gas. The reaction vessel was heated to 110 ° C., 20.0 parts of N, N-dimethylaminoethyl methacrylate, 70.0 parts of stearyl methacrylate, 10 parts of vinyl sulfonic acid, and 2,2′-azobis ( A mixture containing 9.0 parts of 2-methylpropionic acid) dimethyl (V-601 (manufactured by Wako Pure Chemical Industries, Ltd.)) was dropped over 2 hours to carry out a polymerization reaction. After completion of the dropwise addition, the mixture was further reacted at 110 ° C. for 3 hours, 0.9 part of V-601 (manufactured by Wako Pure Chemical Industries) was added, and the reaction was further continued at 110 ° C. for 1 hour to obtain a polymer dispersant 1 solution. Got. The weight average molecular weight (Mw) of the polymer dispersant 1 was 7,120, the acid value was 18 mgKOH / g, and the amine value was 65 mgKOH / g. 1 g of this was sampled and heat-dried at 180 ° C. for 20 minutes to measure the nonvolatile content. Exol D110 was added to the polymer dispersant 1 solution so that the nonvolatile content of the polymer dispersant solution was 50 mass%. As a result, a 50% by mass solution of the polymer dispersant 1 with a nonvolatile content was obtained.

(Synthesis Example of Polymer Dispersant 2-13)
Synthesis was performed in the same manner as in Synthesis Example 1 except that the raw materials and preparation amounts shown in Table 5 were used, and solutions of polymer dispersants 2 to 13 were obtained. The physical property values of each polymer dispersant were as shown in Table 6.

(Synthesis example of comparative polymer dispersants 1 to 3)
Synthesis was carried out in the same manner as in Synthesis Example 1 except that the raw materials and preparation amounts shown in Table 5 were used, and solutions of comparative polymer dispersants 1 to 3 were obtained. The physical property values of each polymer dispersant were as shown in Table 6.

Abbreviations listed in Table 5 are as follows.
DM: N, N-dimethylaminoethyl methacrylate (c-1)
STMA: Stearyl methacrylate (c-3)
LMA: Lauryl methacrylate (c-3)
VSA: vinyl sulfonic acid (c-2)
MESS: 2-methacryloyloxyethyl succinic acid (c-2)
MEAP: 2-methacryloylethyl acid phosphate (c-2)
AmPBA: 3-acrylamidophenylboronic acid (c-2)
2-EHA: 2-ethylhexyl acrylate C-1: R1 = CH3, R2 = CH3, n = 9 in the general formula (1), A = ethylene group (c-4)
C-2: R1 = CH3, R2 = H, n = 9, A = propylene group (c-4) in the general formula (1)

  Table 6 shows physical property values of the obtained polymer dispersant including the weight average molecular weight.

(Coloring agent)
Cyan colorant C.I. I. Pigment Blue 15: 3 (copper phthalocyanine blue)
Lionol Blue FG7919 (Toyo Color)
Magenta colorant C.I. I. Pigment Red 122 (Quinacridone Magenta)
Hosterperm Pink E (manufactured by Clariant)
C. I. Pigment Red 57: 1 (Kermin 6B)
Permanent Rubin L6B (manufactured by Clariant)
Yellow colorant C.I. I. Pigment Yellow 180 (Benz Imidazolone Yellow)
Novoperm Yellow P-HG (manufactured by Clariant)
Black colorant carbon black NIPEX150 (Degussa)
As the blue component, C.I. I. Pigment Blue 15: 3 added

(Pigment dispersant)
Solsperse 24000SC Acid value: 25 mgKOH / g
Basic resin type dispersant (polyamine resin)

(Carrier liquid)
As the carrier liquid, those described in Table 7 were used.

C. I. Pigment Blue 15: 3
(Lionol Blue FG7919) 18 parts by weight binder resin 1 80 parts by weight Solsperse 24000SC 2 parts by weight The above materials (total 5 kg) were mixed in a Henschel mixer having a volume of 20 L (3,000 rpm, 3 minutes) and then biaxially kneaded. Melting and kneading were performed with an extruder (PCM30) at a supply rate of 6 kg / hr and a discharge temperature of 145 ° C., and further, kneading was performed with three rolls having a roll temperature of 140 ° C. After cooling and solidifying, coarsely pulverized with a hammer mill and then finely pulverized with an I-type jet mill (IDS-2 type) to obtain a pulverized cyan product 1 having an average particle size of 5.0 μm.

Furthermore, cyan pulverized product 1 25 parts by mass Exol D130 72 parts by mass polymer dispersant 1 3 parts by mass were weighed, sufficiently stirred and mixed to disperse cyan pulverized product 1 in the Exol D130 solution (slurry concentration was 25% by mass). The slurry in which the cyan pulverized product 1 is dispersed is subjected to a circulation operation for 60 minutes using a wet pulverizer which is a medium agitating mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises Co., Ltd., capacity 1.4 L), Wet grinding was performed. The wet pulverization conditions at this time were as follows. Agitator disk (material: zirconia) peripheral speed 10 m / s, cylinder ZTA, media (material: zirconia) diameter 1.25 mm, filling rate 70%, solution flow rate 45 kg / h, cooling water 5 L / min, pressure 0.1 kg / cm ² . After wet pulverization for 60 minutes, the slurry was taken out and passed through a mesh having an opening of 33 μm (manufactured by SUS304) to obtain a liquid developer 1C (including cyan toner particles 1). When the particle size distribution of the cyan toner particles 1 was confirmed, the average particle size (D50) was 2.4 μm. The viscosity (η) of the liquid developer 1C was 52 mPa · s.

  Using the raw materials shown in Table 8 and Table 9 in the same manner as in Example 1, toner pulverized products and liquid developers were produced, respectively. The particle size was measured using a Nikkiso Co., Ltd. laser diffraction / scattering particle size analyzer Microtrac HRA, the solvent using Exol D80 (Exxsol ™) (ExxonMobil Corporation), and under an environmental condition of 23 ° C. and 50% RH. It is measured. The viscosity (η) of the liquid developer was measured using an E-type viscometer TV-22 manufactured by Toki Sangyo Co., Ltd. After adjusting the solid content in the liquid developer to 25% and fully acclimatizing to 25 ° C, set the 1 ° 34 'cone in the TV-22 type viscosity shape, and measure the viscosity after 1 minute at 20 rpm. Asked.

  In the live-action test, a commercially available liquid developing copier (Savin 870: manufactured by Sabin) was used, an amorphous silicon photoconductor was used under an environmental condition of 23 ° C./50% RH, and the surface potential of the photoconductor was +450. An image test of 1000 sheets was performed from the initial stage with ˜500 V, a residual potential of +50 V or less, and a developing roller bias of +250 to 450 V. The 1000th image was used for the evaluation of the image density and the fixing rate, and the 951th and subsequent images were used for the evaluation of the cold offset resistance. At this time, the image was produced in a single color for each color, the paper was OK topcoat made by Oji Paper, and the thermocompression bonding was performed at a speed of 30 m / min and 160 ° C.

(Image density)
First, the image density was measured by X-Rite 504 in the solid image portion. Here, it is practically preferable that the density value of each color is 1.2 or more for yellow, 1.4 or more for magenta and cyan, and 1.6 or more for black. More preferably, yellow is 1.3 or more, magenta and cyan are 1.5 or more, and black is 1.7 or more.

(Fixing rate)
For the fixing rate, an image density ID (ID1) at the time of output was measured using a printed image in which a solid portion of 1 cm × 1 cm was output. Thereafter, a mending tape (Scotch (registered trademark) 810 manufactured by 3M) was attached to the printed matter, and a 1 kg cylindrical brass weight was rolled and reciprocated once. Thereafter, the mending tape was removed, the image density ID (ID2) was measured again, and a value obtained by calculating (ID2) / (ID1) × 100 was obtained as a fixing rate (%). Here, if the fixing rate is 80% or more, it is practically preferable, and if it is 90% or more, it is more preferable.

(Cold offset resistance)
With respect to cold offset resistance, after being output by the above liquid developing copier, ten output images are sequentially thermocompression bonded by an external fixing device at a speed of 30 m / min and a nip thickness of 6 mm. When the output image was thermocompression bonded, it was confirmed whether or not there was a re-transferred toner image on the tenth output image (paper). The temperature at which the re-transferred toner image does not exist was evaluated in four ranks. Here, if the thermocompression-bonding roll temperature is less than 140 ° C, it is practically preferable, and if it is less than 120 ° C, it is more preferable.
A: Thermocompression roll temperature is less than 120 ° C B: Thermocompression roll temperature is 120 ° C or more and less than 140 ° C C: Thermocompression roll temperature is 140 ° C or more and less than 160 ° C D: Thermocompression roll temperature is 160 ° C or more

(Adsorption rate)
The adsorption rate of the polymer dispersant (C) to the toner particles in the liquid developer was evaluated as follows. 10 g of the obtained liquid developer was weighed, centrifuged at 19,000 rpm for 20 minutes with a centrifugal machine CR22H manufactured by Hitachi Koki Co., Ltd., and 1 g of the separated supernatant solution was weighed, and then heated in a 180 ° C. oven for 1 hour. The carrier liquid (D) is volatilized. Thereafter, the remaining polymer dispersant (C) was weighed, and the adsorption rate to the toner particles was calculated from the obtained value. When the adsorption rate is 50% or more, the dispersion stability of the toner particles becomes high, which is practically preferable, and more preferably 70% or more.
A: Adsorption rate is 70% or more B: Adsorption rate is 50% or more and less than 70% C: Adsorption rate is less than 50%

(Storage stability)
The storage stability of the liquid developer was evaluated as follows. The obtained liquid developer was allowed to stand in a constant temperature and humidity atmosphere at 25 ° C. and 50% for 3 months. The average particle diameter (D50) and viscosity (η) of the liquid developer after 3 months of standing were measured by the methods described above, and evaluated at a rate increased from the value before the start of the test.

(Average particle size (D50))
A: Average particle diameter after test (D50) / average particle diameter before test (D50) is less than 1.1 B: average particle diameter after test (D50) / average particle diameter before test (D50) is 1. 1 or more and less than 1.2 C: average particle diameter after test (D50) / average particle diameter before test (D50) is 1.2 or more Here, average particle diameter after test (D50) / average particle diameter before test If (D50) is less than 1.2, it is practically preferable, and if it is less than 1.1, it is more preferable.

(Viscosity (η))
A: Viscosity after testing (η) / viscosity before testing (η) is less than 1.1 B: viscosity after testing (η) / viscosity before testing (η) is 1.1 or more and less than 1.4 C: Viscosity after test (η) / viscosity before test (η) is 1.4 or more Here, viscosity after test (η) / viscosity before test (η) is less than 1.4, which is practically preferable. If it is less than 1.1, it is more preferable.

Detailed physical property values and test results of the liquid developer are shown in Table 10.

  Comparative Examples 1 and 4 to 6 do not include an ethylenically unsaturated monomer (c-2) having at least one acid group selected from carboxylic acid, sulfonic acid, phosphoric acid, and boronic acid. Sufficient storage stability cannot be obtained, and fixing rate and cold offset resistance are inferior. In Comparative Example 2, since the ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms was not included, sufficient storage stability could not be obtained. Since Comparative Example 3 does not contain an ethylenically unsaturated monomer (c-1) having an amino group, the average particle size is large, a sufficient image density cannot be obtained, and sufficient storage stability is obtained. I couldn't. On the other hand, the liquid developer using the polymer dispersant (C) has practical areas of image density, fixing rate, cold offset resistance, and storage stability. In addition, among liquid developers using cyan toner, it was found that Examples 5 and 6 were particularly excellent in terms of image density, fixing rate, and storage stability. In addition, a printed matter excellent in color development and color reproducibility was obtained because of excellent density, fixing property, and cold offset resistance.

  The polymer dispersant for a liquid developer according to an embodiment of the present invention is excellent in color developability, storage stability, fixability, and cold offset resistance, and uses an electrophotographic method, an electrostatic recording method, or the like. It is preferably used as a polymer dispersant used for developing an electrostatic latent image in an electronic copying machine, a printer, an on-demand printing machine or the like that is formed.

Claims (9)

 An ethylenically unsaturated monomer (c-1) having an amino group and an ethylenically unsaturated monomer having at least one acid group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, and a boronic acid group A polymer dispersant for a liquid developer comprising a copolymer of a monomer (c-2) and an ethylenically unsaturated monomer (c-3) having an alkyl group having 9 to 24 carbon atoms.  The polymer dispersant has a weight average molecular weight Mw of 500 to 40,000, an amine value of 5 to 150 mgKOH / g, and an acid value of 5 to 40 mgKOH / g. Item 2. The polymer dispersant for liquid developer according to Item 1. The copolymer is ethylenic represented by the monomer (c-1), the monomer (c-2), the monomer (c-3), and the following general formula (1). The polymer dispersant for liquid developer according to claim 1, which is a copolymer with an unsaturated monomer (c-4).
General formula (1)
CH ₂ = C (R ¹ ) COO (AO) _n R ²
(Wherein R ¹ represents a hydrogen atom or a methyl group,
R ² represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms,
n represents an integer of 1 to 200,
A represents an alkylene group having 2 to 4 carbon atoms. )   A liquid developer comprising at least a binder resin (A) containing a polyester resin, a colorant (B), a polymer dispersant (C), and a carrier liquid (D), wherein the polymer dispersant (C) is: A liquid developer, which is the polymer dispersant according to claim 1.  The liquid development according to claim 4, wherein the acid value of the binder resin (A) is 5 to 40 mgKOH / g, and the glass transition temperature (Tg) is 50 to 65 ° C. Agent.  The liquid developer according to claim 4, wherein the carrier liquid (D) is an aliphatic hydrocarbon.  The ratio of primary carbon is 55% or more and the ratio of secondary carbon is 30% or less with respect to the total number of primary to tertiary carbons of the aliphatic hydrocarbon. The liquid developer according to claim 6.  The liquid developer according to claim 6 or 7, wherein the carrier liquid (D) has a dry point of 230 to 360 ° C and an aniline point of 75 to 100 ° C.  A printed matter which is a developer of the liquid developer according to claim 4.