JP2015184496A - Liquid developer and printed matter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer exhibiting excellent storage stability and fixability and giving excellent image density in continuous printing without degradation in qualities.SOLUTION: The liquid developer comprises at least a binder resin (A), a colorant (B), a polymer dispersant (C), a carrier liquid (D), and an antioxidant (E). The binder resin (A) contains at least a polyester resin; the carrier liquid (D) comprises an aliphatic hydrocarbon having a dry point of 180°C to 280°C in a distillation range; and the antioxidant (E) can be dissolved by 10 mass% or more at 25°C in the carrier liquid (D).

Description

  The present invention relates to a liquid developer and printed matter using the same.

  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, and the toner particles are required to have coloring property, fixing property, charging property, 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. It is hoped that

  In an electrophotographic image forming apparatus using a liquid developer, a non-contact charging device (scorotron charger) is employed as a charging device for a latent image carrier of an organic photoreceptor or an amorphous silicon photoreceptor. However, when such a charging device is used, the carrier liquid is oxidized by the generated ozone, and the oxide adheres to the surface of the photoconductor, thereby deteriorating the image quality and the continuous printing stability. Arise.

  Patent Documents 1 and 2 describe that an antioxidant is added to the liquid developer, and the addition of the antioxidant is considered to suppress the oxidation of the carrier liquid by the generated ozone. However, these liquid developers have problems that a sufficient image density cannot be obtained, and that the fixability and storage stability are poor.

JP 2009-169262 A JP 2008-242039 A

  As described above, the liquid developer has excellent continuous printing stability and image quality, and there is room for improvement in obtaining excellent storage stability and fixability. There is a need for a liquid developer that solves this problem, has excellent storage stability and fixability, and has no image quality deterioration during continuous printing, and has an excellent image density.

  Therefore, an embodiment of the present invention provides a liquid developer having excellent continuous printing stability, excellent fixability and image density, and excellent storage stability over a long period of time, and a printed matter obtained using the same. The purpose is to do.

  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 embodiment of the present invention is a liquid developer comprising at least a binder resin (A), a colorant (B), a polymer dispersant (C), a carrier liquid (D), and an antioxidant (E). The binder resin (A) contains at least a polyester resin, the carrier liquid (D) is composed of an aliphatic hydrocarbon having a dry point in the distillation range of 180 ° C. to 280 ° C., and the antioxidant (E). The present invention relates to a liquid developer, which is an antioxidant that dissolves at 10% by mass or more at 25 ° C. with respect to the carrier liquid (D).

  An embodiment of the present invention also relates to the liquid developer, wherein the antioxidant (E) is compatible with the binder resin (A) at 25 ° C.

  An embodiment of the present invention also relates to the liquid developer, wherein the binder resin (A) further contains a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin.

  An embodiment of the present invention also relates to the liquid developer, wherein the antioxidant (E) is contained in an amount of 0.01 to 5.0% by mass in the liquid developer.

  An embodiment of the present invention also relates to the liquid developer, wherein the antioxidant (E) includes at least a phenolic antioxidant.

  In the embodiment of the present invention, the polymer dispersant (C) is ethylene containing at least an ethylenically unsaturated monomer having an amino group (c-1) and an alkyl group having 9 to 24 carbon atoms. The liquid developer obtained by polymerizing the polymerizable unsaturated monomer (c-2) and having an amine value of 5 to 150 mgKOH / g of the polymer dispersant (C).

Furthermore, other embodiment of this invention is related with the printed matter obtained using the said liquid developer.

  According to an embodiment of the present invention, a liquid developer having excellent continuous printing stability, excellent fixability and image density, and excellent storage stability over a long period of time, and a printed matter obtained using the same are provided. can do.

Hereinafter, the present invention will be described in detail.
The liquid developer according to the embodiment of the present invention includes at least a binder resin (A), a colorant (B), a polymer dispersant (C), a carrier liquid (D), and an antioxidant (E). A liquid developer, wherein the binder resin (A) contains at least a polyester resin, the carrier liquid (D) comprises an aliphatic hydrocarbon having a dry point in the distillation range of 180 ° C. to 280 ° C., and is oxidized A significant feature is that the inhibitor (E) is an antioxidant that dissolves at 10% by mass or more at 25 ° C. with respect to the carrier liquid (D).

  The presence of the antioxidant (E) in the liquid developer suppresses the oxidation of the carrier liquid by ozone generated in the scorotron charger, and suppresses the deterioration of print quality in continuous printing. Further, since the antioxidant (E) is dissolved in the carrier liquid (D) at 25 ° C. at 10% by mass or more, it is present in the carrier liquid without being adsorbed on the toner particles. The storage stability excellent as a liquid developer can be obtained without inhibiting the adsorption of the agent (C) to the toner particles.

  Further, the binder resin (A) contains at least a polyester resin, so that a liquid developer having excellent color developability and storage stability can be obtained from the excellent pigment dispersibility of the polyester resin. In addition, a liquid developer having excellent fixability and offset resistance can be obtained.

  Furthermore, by using aliphatic hydrocarbon as the carrier liquid (D), the binder resin (A) including at least the polyester resin is not dissolved, and the toner particles can be stably dispersed in the carrier liquid. A liquid developer having high storage stability can be obtained. Further, when the dry point in the distillation range of the carrier liquid is 180 ° C. to 280 ° C., the carrier liquid is sufficiently volatilized in the print drying process, and excellent fixability can be obtained. When the dry point is lower than 180 ° C., there is a problem that in the printing process, the carrier liquid is extremely dried on the roller, and good transferability cannot be maintained, and an excellent image density cannot be obtained. When the dry point is higher than 280 ° C., the fixing property is inferior, the viscosity as a liquid developer is likely to be high, the mobility of toner particles at the time of development is inferior, and high-speed development cannot be performed, and a sufficient image density is obtained. Problems such as inability to obtain.

  Hereinafter, the binder resin (A), the colorant (B), the polymer dispersant (C), the carrier liquid (D), the antioxidant (E), and the like included in 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 and a charge control 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. The binder resin (A) contains at least a polyester resin (a-1) from the viewpoints of pigment dispersibility, grindability, and fixability.

  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 (1); glycerol, diglycerol, sorbit, sorbitan, butanetriol, trimethylolethane, trimethylolpropane, pentaerythritol, dipe Data erythritol, trihydric or higher alcohols such as tripentaerythritol; and the like. These are used alone or in combination of two or more.

General formula (1)

(In the formula, 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).

  As the acid component, 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, sebacic acid and azelaic acid Or 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, glutaconic acid or the anhydride; cyclohexane Dicarboxylic acid; naphthalenedicarboxylic acid; diphenoxyethane-2,6-dicarboxylic acid or anhydride thereof; Trivalent or higher carboxylic acids that function as crosslinking components include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid, hexanetricarboxylic acid, tetra (methylenecarboxyl) methane, octanetetracarboxylic acid, benzophenonetetracarboxylic acid, Or these anhydrides etc. are mentioned. 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, antimony trioxide, titanium tetrabutoxide, manganese acetate, and zinc acetate. 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 in order to control the molecular weight, softening temperature, etc. of the polyester resin, the kind of alcohol component and carboxylic acid to be reacted, molar ratio, reaction temperature, reaction What is necessary is just to adjust time, reaction pressure, a catalyst, etc. 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.).

  Binder resin (A) can use other resin together as needed. Preferred binder resins that can be used in combination include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene-p-chlorostyrene copolymer, and styrene-vinyltoluene copolymer. Polymer, styrene-vinyl naphthalene copolymer, styrene- (meth) acrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Styrene copolymers such as styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, and cross-linking Styrene copolymer; poly Vinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral resin, Examples include terpene resins, coumarone indene resins, and petroleum resins. 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.

  Furthermore, in order to improve fixability and grindability, the binder resin (A) is at least selected from the group consisting of a polyester resin (a-1), a styrene resin, an acrylic resin, and a styrene-acrylic copolymer resin. It is preferable to contain 1 type of resin (a-2) (henceforth only resin (a-2)). 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, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p -Methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, and the like.

  Examples of the (meth) acrylic acid esters used for 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, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-chloroethyl (meth) acrylate, Examples include phenyl (meth) acrylate, dimethylaminoethyl acrylate, and diethylaminoethyl (meth) 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, in order to control the molecular weight and softening temperature of styrene-acrylic copolymer resin, the types and molar ratios of the styrene monomer, (meth) acrylic acid and (meth) acrylic acid ester, as well as the reaction temperature and reaction time. The reaction pressure, polymerization initiator, crosslinking agent, etc. may be adjusted. 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) And a method of polymerizing by adding a monomer for the other resin in the presence of one of the polymerized polyester resin (a-1) and resin (a-2). . 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 | combine by well-known methods like the method of the patent 3531980 and Unexamined-Japanese-Patent 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, it may be either a method in which both are dissolved in a solvent and mixing and desolvation are performed, or melt kneading is performed.

  Furthermore, the mass ratio [(a-2) / (a-1)] of the polyester resin (a-1) and the resin (a-2) contained in the binder resin (A) is preferably 1 or less. More preferably, the mass ratio is 0.5 or less. When the mass ratio exceeds 1, the pulverizability of the toner particles is lowered, and the color developability and storage stability as a liquid developer are lowered.

(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 85 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).

  If the softening temperature of the binder resin (A) is lower than 80 ° C., the binder resin (A) is too soft at the time of kneading, the dispersibility of the colorant (B) is lowered, and it becomes difficult to obtain a sufficient image density as a liquid developer. There is a case. 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 and transfer to the next paper, and a hot offset phenomenon is likely to occur. On the other hand, when the softening temperature is higher than 140 ° C., it is difficult to obtain good fixability, and there are cases where problems such as lowering of pulverizability and lowering of color developability may occur.

(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 smaller than 2,000, the hot offset resistance, color reproducibility, and dispersion stability may be deteriorated. When the weight average molecular weight (Mw) is larger than 100,000, the fixing property and Cold offset resistance may be reduced. 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

  Furthermore, in the molecular weight measured by gel permeation chromatography (GPC), the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the binder resin (A) is in the range of 2-18. It is preferable that When Mw / Mn is less than 2, the offset resistance is lowered, the non-offset region is narrowed, and the low-temperature fixability is sometimes lowered. When Mw / Mn exceeds 18, the pulverizability of the toner particles becomes low, and there are cases where the image characteristics are deteriorated such that a sufficient image density cannot be obtained and the color developability is lowered.

  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. If the amount is less than 60 parts by mass, the fixability and offset resistance may decrease. If the amount exceeds 95 parts by mass, the ratio of the binder resin (A) to the colorant (B) increases, and toner particles As a result, the coloring power may decrease, and the image density may decrease.

(Acid value)
The acid value of the binder resin (A) is preferably 3 to 70 mgKOH / g, and more preferably 10 to 40 mgKOH / g. When the acid value is lower than 3 mg KOH / g, the polymer dispersant is hardly adsorbed on the binder resin, the dispersion stability of the toner particles is deteriorated, and the storage stability of the liquid developer is deteriorated. When the acid value is higher than 70 mgKOH / g, the chargeability of the toner particles is lowered, and problems such as insufficient image density and poor color development and color reproducibility are caused. The acid value of the binder resin (A) is the number of mg of potassium hydroxide (KOH) necessary for neutralizing the acid contained in 1 g of the binder resin (A), and is an ethanol / toluene mixed solvent. It is the value titrated with KOH solution.

(Colorant (B))
As the colorant (B), yellow, magenta, cyan, and black organic pigments and organic dyes shown below, in particular, salt-forming compounds thereof; carbon black; magnetic substances 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, 168, 174, 176, 180, 181, 191 and the like 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. Examples of the salt forming compound of the acid dye include C.I. I. It is preferable to use a salt-forming compound comprising acid yellow 11 or 23 (tartrazine) and a quaternary ammonium salt compound. By constituting the quaternary ammonium salt, the toner particles can maintain a stable positive charge.

  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, 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, rhodamine lake pigments, naphthol pigments, and the like are preferably used. Specifically, naphthol AS (CI Pigment Red 269 etc.), rhodamine lake (CI Pigment Red 81, 81: 1, 81: 2, 81: 3, 81: 4, 169 etc.), quinacridone (C.I. Pigment Red 122 etc.) Carmine 6B (C.I. Pigment Red 57: 1) is a preferred material. A combination of a quinacridone pigment and a monoazo pigment Carmine 6B (CI Pigment Red 57: 1) 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. Examples of the salt forming compound of the basic dye include C.I. I. It is preferable to use a salt-forming compound comprising Basic Red 1 or Basic Violet 10 and colorless (does not inhibit coloring of the pigment) organic sulfonic acid or organic carboxylic acid. Since the basic dye exhibits a good positive charge, the toner particles can maintain a stable positive charge. As the organic sulfonic acid, naphthalenesulfonic acid, naphtholsulfonic acid, naphthylaminesulfonic acid and the like are preferably used. As the organic carboxylic acid, salicylic acid derivatives, higher fatty acids and the like are 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. Triarylmethane dyes are effective materials in terms of both charge control and colorability because they have good positive chargeability. In particular, C.I. I. A triarylmethane oil-soluble dye such as Solvent Blue 124 or a salt-forming compound of a triarylmethane basic dye is good. C. I. As the solvent blue 124, specifically, COPY BLUE PR manufactured by Clariant is a preferable material. This is C.I. I. It was obtained by condensing Basic Red 9 (paramagenta) and aniline. Further, for the purpose of adjusting the hue, in addition to the cyan or blue organic pigment, the salt forming compound of cyan or blue dye, the oil-soluble dye of cyan or blue dye, a green pigment can be used as a complementary color. 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. Nigrosine refinement can be obtained by the method described in JP-A-2006-171501. Further, as the black colorant, black can be obtained using the above three colorants of yellow, magenta, and cyan.

  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. Pigment Violet 19, a salt-forming compound composed of a triarylmethane-based basic dye and a substantially colorless organic acid (a salt-forming compound of CI Basic Blue 7 and an organic acid), a triarylmethane-based oil-soluble dye Etc. are preferably used. Triarylmethane dyes are effective in controlling the chargeability of toner particles by exhibiting good positive charge, and among them, triarylmethane oil-soluble dyes having excellent dispersibility are preferred.

  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 containing toner particles to uniformly disperse the toner particles and improve development characteristics. However, the polymer dispersant (C) is a carrier. It may be added in the liquid or in 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 not particularly limited and known ones can be used, but at least an ethylenically unsaturated monomer (c-1) having an amino group and an alkyl having 9 to 24 carbon atoms. A copolymer obtained from a copolymerizable polymerizable monomer containing an ethylenically unsaturated monomer (c-2) having a group is preferred from the viewpoint of dispersibility.

 In accordance with the molecular weight of the intended polymer dispersant (C), an ethylenically unsaturated monomer (c-1) having an amino group and an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms The polymer dispersant (C) can be obtained by mixing and heating the body (c-2) and optionally a polymerization initiator, a chain transfer agent and the like. The reaction temperature is 40 to 150 ° C, preferably 50 to 110 ° C.

  The ethylenically unsaturated monomer 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 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, alkyl (meth) acrylamides, which are examples of an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms, cannot obtain the effect exhibited by an ethylenically unsaturated monomer having an amino group. Among the ethylenically unsaturated monomers having an amino group, examples of the ethylenically unsaturated monomer having a tertiary amino group include N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl. N, N-dialkylamino group-containing (meth) acrylic acid esters such as (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate; N, N-dimethyl Contains N, N-dialkylamino groups such as aminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, and N, N-diethylaminopropyl (meth) acrylamide (Meth) acrylamides; dimethylaminostyrene, Ethylamino styrene; and the like.

  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 types of ethylenically unsaturated monomers having an amino group may be used in combination.

  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 lower than 5 mgKOH / g, the adsorption to the toner particles is weak, and the pulverizability in wet pulverization may be deteriorated. Furthermore, during storage for a long period of time, toner particles may aggregate, resulting in an increase in the viscosity and average particle size of the liquid developer, which may deteriorate storage stability. When the amine value is higher than 150 mgKOH / g, the chargeability of the toner particles is deteriorated, the toner particles are hardly transferred to the substrate, and a good image density may not be obtained. Furthermore, the solubility in the carrier liquid is lowered, and the grindability may be deteriorated. The amine value of the polymer dispersant (C) is the total amine value (mgKOH / g) measured according to the method of ASTM D2074.

  Moreover, among the polymer dispersant (C), the ethylenically unsaturated monomer (c-2) containing an alkyl group having 9 to 24 carbon atoms has an alkyl group having 9 to 24 carbon atoms to the carrier liquid. It improves the solubility, improves the pulverization property in wet pulverization, and exerts effects such as suppressing the increase in the viscosity of the liquid developer. Furthermore, during storage for a long period of time, aggregation of toner particles and increase in the viscosity of the liquid developer can be suppressed, and excellent storage stability can be obtained. When the carbon number of the alkyl group is larger than 24, when the liquid developer is fixed to the substrate, the long alkyl group may interfere with the contact of the toner particles and the fixability may be deteriorated. Furthermore, the chargeability of the toner particles is deteriorated, the toner particles are difficult to be transferred to the substrate, and a sufficient image density may not be obtained.

Examples of the ethylenically unsaturated monomer (c-2) containing 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- (meth) acrylate methyldecyl (meth) acrylate, undecyl (meth) acrylate, 2-methyl Undecyl (meth) acrylate, 9-ethylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, 11-methyldodecyl (meth) acrylate, tridecyl (meth) acrylate, 2-methyl Tridecyl (meth) acrylate, tetradecyl (meth) acrylate, 2-methyltetradecyl (meth) acrylate, pentadecyl (meth) acrylate, 2-methylpentadecyl (meth) acrylate, hexadecyl (meta Acrylate, 2-methylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 2-methylheptadecyl (meth) acrylate, octadecyl (meth) acrylate, 2-methyloctadecyl (meth) acrylate, nonadecyl (meth) acrylate, 2 -(Meth) acrylates such as alkyl (meth) acrylates having 9 to 24 carbon atoms such as methylnonadecyl (meth) acrylate, icosyl (meth) acrylate, heicosyl (meth) acrylate, docosyl (meth) acrylate; and
N-nonyl (meth) acrylamide, N- (8-methylnonyl) (meth) acrylamide, N-decyl (meth) acrylamide, N, N-didecyl (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- (1-methyltridecyl) (meth) acrylamide, N-tetradecyl (meth) acrylamide, N, N-ditetradecyl (meth) acrylamide, N-pentadecyl (meth) acrylamide, N- (1-methylpentadecyl) (meth) acrylamide, N-hexadecyl (meth) acrylamide, N, N-dihexadecyl acrylic Nido, N-heptadecyl (meth) acrylamide, N- (1-methylheptadecyl) acrylamide, N-octadecyl (meth) acrylamide, N, N-dioctadecylacrylamide, N-nonadecyl (meth) acrylamide, N-icosyl (meta) ) Alkyl (meth) acrylamides having 9 to 24 carbon atoms such as acrylamide, N-henicosyl (meth) acrylamide, N-docodecyl (meth) acrylamide; and
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 containing an aromatic ring and an alkyl group having 9 to 24 carbon atoms, such as N-octadecyl-N- [2- (1-naphthyl) ethyl] (meth) acrylamide;
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. Examples thereof include α-olefins containing a group.

  Among these, (meth) acrylates such as alkyl (meth) acrylates having 9 to 24 carbon atoms are preferable from the viewpoint of dispersibility.

(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.

(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, heptyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) ) (Meth) acrylates such as alkyl (meth) acrylates having 1 to 8 carbon atoms such as acrylate; N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acryl Amide, N-butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-isopentyl (meth) acrylamide, N-neopentyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-isohexyl (meth) (Meth) such as acrylamide, Nn-heptyl (meth) acrylamide, N- (6-methylheptyl) (meth) acrylamide, N-octyl (meth) acrylamide, N- (7-methyloctyl) (meth) acrylamide Acrylamides: 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-nonene, 2-nonene, 1-decene, 2-decene, etc. α- olefins having 8 alkyl group; and the like.

  Further, the weight average molecular weight (Mw) of the polymer dispersant (C) is not limited to a specific range, but in consideration of dispersibility and pulverization properties when the toner particles are wet-dispersed, gel permeation chromatography ( The molecular weight measured by GPC) is preferably 500 to 40,000, and more preferably 2,000 to 30,000. The weight average molecular weight (Mw) can be measured by the method described above.

  The polymer dispersant (C) is preferably added in an amount of 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 0.1-5 mass parts. When the amount is less than 0.1 part by mass, the dispersibility and pulverization property of the toner particles may be lowered, and the storage stability may be lowered. It is possible to improve the dispersibility and grindability of the toner particles by changing the dispersion method and lengthening the dispersion time, but this causes an increase in the viscosity of the liquid developer, thereby reducing the transferability and color developability. It may be a cause. When the addition amount is more than 10 parts by mass, the chargeability of the toner particles is lowered, and there may be a problem that a sufficient image density cannot be obtained and the fixing property is lowered. 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, a dispersant conventionally used for a liquid developer may be used. Specifically, fatty acid metal salts such as cobalt naphthenate, zinc naphthenate, copper naphthenate, manganese naphthenate, cobalt octylate and zirconium octylate, titanate coupling agents of organic titanates such as lecithin and titanium chelate, alkoxy Examples include titanium polymers, polyhydroxy titanium carboxylate compounds, titanium alkoxides, succinimide compounds, polyimine compounds, fluorine-containing silane compounds, and pyrrolidone compounds. In particular, titanium alkoxide, a succinimide compound, a fluorine-containing silane compound, a pyrrolidone-based compound, and the like may be mixed and used in an appropriate amount within a range of 5 parts by mass or less with respect to 100 parts by mass of the liquid developer. In this case, the dispersant is used in such a manner that the dispersant having the same polarity as the toner particles is adsorbed on the toner particles, and the dispersant having the opposite polarity to the toner particles is not adsorbed on the toner particles and dispersed in the carrier liquid. It becomes a form to make it. At this time, the standard for discussing the polarity is the polarity with respect to the carrier liquid. In addition, this behavior is determined after an actual image test and is obtained empirically.

(Carrier liquid (D))
As the carrier liquid (D) used in the liquid developer, those having lipophilicity, chemically stable and insulating properties are preferable, and good storage stability and good toner particle dispersibility are obtained. In order to obtain the desired toner particle size, aliphatic hydrocarbons are preferred. Examples of the aliphatic hydrocarbon include linear paraffin hydrocarbons, isoparaffin hydrocarbons, and naphthene hydrocarbons. Among these, paraffinic hydrocarbons with very little residual aromatic hydrocarbon are preferable. 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 180 ° C to 280 ° C. When the dry point is less than 180 ° C., the carrier liquid is remarkably dried on a roller such as a photoreceptor in the printing process, and good transferability cannot be maintained, and an excellent image density cannot be obtained. There's a problem. On the other hand, if the dry point is higher than 280 ° C., it becomes difficult to remove the carrier liquid and the fixability is inferior, and the viscosity as a liquid developer tends to be high. Problems such as inability to develop and sufficient image density cannot occur. Here, the dry point in the distillation range is determined by the method defined by ASTM D86, ASTM D1078, and JIS K2254. Moreover, as a carrier liquid (D), it is preferable to use what has a Kauri butanol numerical value (KB value: ASTM D1133) 30 or less. More preferably, it is the range of 20-30. The aniline point (JIS K2256) is preferably in the range of 60 to 105 ° C., more preferably 70 to 95 ° C., in order to obtain a stable carrier liquid. When the Kauributanol value exceeds 30 or the aniline point is lower than 60 ° C., the solubility as a solvent is high and the carrier liquid dissolves the toner particles, so the storage stability and color reproducibility of the toner particles are low. In some cases, the carrier liquid may be colored to contaminate a substrate such as paper. When the aniline point exceeds 105 ° C., the compatibility with the dispersant and additives added when dispersing the toner particles in the carrier liquid is low, causing problems such as poor dispersion and insufficient image density. There is a case.

Specifically describing the insulating properties of the carrier liquid (D), the dielectric constant is 5 or less, preferably 1 to 5, and more preferably 1 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 ¹⁰ 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 less than 10 ⁹ Ω · cm, the chargeability of the toner particles becomes low, a sufficient image density cannot be obtained, and color reproducibility and color developability may be lowered.

Further, the density (JIS K2249) at 15 ° C. of the carrier liquid (D) is preferably in the range of 0.70 to 0.85 g / cm ³ . More preferably, it is the range of 0.73-0.83 g / cm < ³ >. This range is preferable because toner particles and a dispersant can exist stably, and thus excellent fixing properties and image density can be obtained. The carrier liquid (D) preferably has a kinematic viscosity (ASTM D445) in the range of 1 to ²⁰ mm ² / s. Especially preferably, it is the range of 1-15. This range is preferable in that the charged particles can be moved at the time of the phenomenon, and have sufficient volatility, and the carrier liquid can be easily removed from the medium on which the final image is formed in the fixing step. If the kinematic viscosity is less than 1 mm ² / s, the liquid developer has a low viscosity, so that the transfer property to the developing roller is low, and a sufficient image density may not be obtained. Further, since the toner particles after development are likely to move, the fineness of the image may be easily lost. On the other hand, if the kinematic viscosity is greater than 20 mm ² / s, the fluidity of the toner particles cannot be obtained and electrophoresis is difficult to occur, and a sufficient image density may not be obtained. Furthermore, since the permeability to a substrate such as paper is low, it is difficult to remove the carrier liquid when the toner particles are fixed, and sufficient fixability may not be obtained. In particular, the fixability in a superimposed image may be greatly reduced.

Specifically preferred carrier liquids (D) are branched paraffins such as “Isopar ^™ M” (Exxon Mobil Corporation), “IP Solvent 2028” (Idemitsu Kosan), in particular. Solvent mixtures, especially isoparaffinic hydrocarbons, or naphthenic hydrocarbons such as “Exsol D110” (Exxsol ™) (Exxon Mobil Corporation), “AF Solvent No. 4” (JX Nippon Oil & Energy) It is preferable.

(Antioxidant (E))
When the carrier liquid (D) is oxidized by the ozone generated by the scorotron charger, the oxide adheres to the surface of the photoreceptor, and a sufficient image density cannot be obtained. Degradation of image quality such as no image output. Furthermore, in continuous printing over a long period of time, the oxide of the carrier liquid (D) accumulates on the surface of the photoconductor, damaging the intermediate transfer body, the image density is not stable, and unnecessary line streaks are generated. cause. The antioxidant (E) can suppress oxidation of the carrier liquid (D) due to its antioxidant effect.

  The antioxidant (E) used in the present invention dissolves 10% by mass or more at 25 ° C. with respect to the carrier liquid (D). When the solubility in the carrier liquid is less than 10% by mass, the antioxidant exists on the surface of the toner particles and inhibits the adsorption of the polymer dispersant (C) to the toner particles. Deteriorates. For the evaluation of solubility, a 10% by mass antioxidant solution is prepared with respect to the carrier liquid, stirred at 50 ° C. for 1 hour, cooled to 25 ° C., and the state of the solution after 2 hours is visually determined. .

  Antioxidant (E) should just dissolve | melt at 10 mass% or more at 25 degreeC in the carrier liquid to be used, and well-known things, such as a phenolic antioxidant, an amine antioxidant, and a phosphorus antioxidant, are used. Can be used alone or in combination. Among these, since antioxidant performance is favorable, it is preferable to contain a phenolic antioxidant.

Examples of the phenolic antioxidant include 2,6-di-tert-butylphenol (hereinafter, tertiary butyl is abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol, 2 , 6-Di-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl 6-t-butylphenol, 4,4′-methylenebis (2,6-diphenol) -T-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 4,4'-bis (2-methyl-6-t-butylphenol), 2,2'-methylenebis (4 -Methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4 ' -Iso Propylidenebis (2,6-di-t-butylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,2'-methylenebis (4-methyl-6-nonylphenol), 2,2 ' -Isobutylidenebis (4,6-dimethylphenol), 2,6-bis (2'-hydroxy-3'-t-butyl-5'-methylbenzyl) -4-methylphenol, 3-t-butyl- 4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4-hydroxy-3,5-di -T-butylphenyl) stearyl propionate, oleyl 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4-hydroxy- , 5-Di-t-butylphenyl) dodecyl propionate, 3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, 3- (4-hydroxy-3,5-di-t -Butylphenyl) octylpropionate, tetrakis {3- (4-hydroxy-3,5-di-t-butylphenyl) propionyloxymethyl} methane, 3- (4-hydroxy-3,5-di-t-butyl) Phenyl) propionic acid glycerin monoester, ester of 3- (4-hydroxy-3,5-di-t-butylphenyl) propionic acid and glycerin monooleyl ether, 3- (4-hydroxy-3,5-di-) t-butylphenyl) propionic acid butylene glycol diester, 3- (4-hydroxy-3,5-di-t-butylphenyl) propion Thiodiglycol diester, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 2,2′-thiobis (4- Methyl-6-tert-butylphenol), 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4- (N, N′-dimethylaminomethylphenol) ), Bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide, tris {(3,5-di-t-butyl-4-hydroxyphenyl) propionyl-oxyethyl} isocyanurate, tris (3 5-Di-tert-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate Bis {2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl} sulfide, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6- Dimethylbenzyl) isocyanurate, tetraphthaloyl-di (2,6-dimethyl-4-tert-butyl-3-hydroxybenzylsulfide), 6- (4-hydroxy-3,5-di-tert-butylanilino) -2 , 4-bis (octylthio) -1,3,5-triazine, 2,2-thio- {diethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl)} propionate, N, N′-hexamethylene bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamide), 3,9-bis [1,1-dimethyl-2- {β- (3-t-butyl-4- Hydro Ci-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-t -Butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, bis {3,3'-bis- (4 '-Hydroxy-3'-t-butylphenyl) butyric acid} glycol ester, styrenated phenol, distyrenated phenol, tristyrenated phenol, and the like.
Among them, 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, 2,6-di-butyl-4-methylphenol, 2,6-di-t-butyl -4-Ethylphenol, 2,4-dimethyl 6-tert-butylphenol, alkyl 3- (4-hydroxy-3,5-di-tert-butylphenyl) propionate, and styrenated phenols are added to the carrier liquid (D ) And the solubility is favorable.

Examples of amine-based antioxidants include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2. -Naphthylamine antioxidants such as naphthylamine; N, N'-diisopropyl-p-phenylenediamine, N, N'-diisobutyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N ' -Di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N '-Phenyl-p-phenylenediamine, dioctyl-p-phenyle Phenylenediamine antioxidants such as diamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine; dipyridylamine, diphenylamine, p, p'-di-n-butyldiphenylamine, p, p'-di- t-butyldiphenylamine, p, p'-di-t-pentyldiphenylamine, p, p'-dioctyldiphenylamine, p, p'-dinonyldiphenylamine, p, p'-didecyldiphenylamine, p, p'-didodecyl Diphenylamine oxidation such as diphenylamine, p, p'-distyryldiphenylamine, p, p'-dimethoxydiphenylamine, 4,4'-bis (4-α, α-dimethylbenzoyl) diphenylamine, p-isopropoxydiphenylamine, dipyridylamine Inhibitor; phenothiazi And phenothiazine antioxidants such as N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazinecarboxylic acid ester and phenoselenadine.
Among these, a diphenylamine antioxidant is preferable because of its good solubility in the carrier liquid (D).

Examples of phosphorus antioxidants include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, trimethyl phosphite, triethyl phosphite, tri-n-butyl phosphite, trioctyl phosphite, tris. (2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, trioleyl phosphite, tristridecyl phosphite, tricetyl phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, Diphenyl mono (tridecyl) phosphite, trilauryl thiophosphite, diethyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, diphe Hydrogen phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, tetra (C12-C15 alkyl) -4,4'-isopropylidene diphenyldiphosphite, bis (tridecyl) Examples include pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl phosphite), and the like.
Among them, trioctyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, trioleyl phosphite, tristridecyl phosphite and the like have solubility in the carrier liquid (D). Good and preferred.

  As the known antioxidant, since the carrier liquid (D) made of an aliphatic hydrocarbon is nonpolar, the polar hydroxyl group, amino group, and phosphite group are preferably monofunctional.

  Moreover, it is preferable that antioxidant (E) used for this invention is compatible with binder resin (A) at 25 degreeC. If the compatibility with the binder resin (A) is poor, the toner particles are transferred to the base material, and when the carrier liquid (D) is removed, the contact and coalescence of the toner particles are deteriorated. It becomes difficult to form a film. As a result, problems such as degradation of image quality such as insufficient image density and degradation of fixability to the substrate may occur. For the evaluation of compatibility, a MEK solution of a binder resin and an antioxidant is prepared and applied on a glass plate with a wet film thickness of 20 μm, and then the state of the coating film after MEK drying is visually determined.

  Further, the antioxidant (E) is preferably contained in the liquid developer in an amount of 0.01 to 5.0% by mass. If the content is less than 0.01%, the antioxidant effect may not be obtained. If the content exceeds 5.0%, problems such as deterioration in storage stability and chargeability of the liquid developer may occur. is there.

(Other additives)
(Pigment dispersant)
Examples of pigment dispersants that are internally added to the toner particles include polyamine-based resin-type dispersant Solsperse 24000SC, Solsperse 32000 (manufactured by Lubrizol Corporation), Azisper PB821 (manufactured by Ajinomoto Fine-Techno Corporation); resin-type dispersant of acrylic copolymer 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).

(Dye derivative)
In the toner particles, it is also possible to use a dye derivative as long as the color developability of the colorant (B) is not impaired. Examples of the dye derivative include a compound in which a basic substituent, an acidic substituent, or an optionally substituted phthalimidomethyl group is introduced into an organic dye (organic pigment, organic dye), anthraquinone, acridone, or triazine. Can be mentioned. Of these, pigment derivatives are preferred, and the structure is a compound represented by the following general formula (2).
P-Ln Formula (2)
(Wherein P is an organic pigment residue, anthraquinone residue, acridone residue or triazine residue, L is a basic substituent, an acidic substituent, or an optionally substituted phthalimidomethyl group, n Is an integer from 1 to 4)
Examples of the organic pigment constituting the organic pigment residue of P include, for example, diketopyrrolopyrrole pigments; azo pigments such as azo, disazo and polyazo; phthalocyanine pigments such as copper phthalocyanine, halogenated copper phthalocyanine and metal-free phthalocyanine Anthraquinone pigments such as aminoanthraquinone, diaminodianthraquinone, anthrapyrimidine, flavantron, anthanthrone, indanthrone, pyranthrone, violanthrone; quinacridone pigments; dioxazine pigments; perinone pigments; perylene pigments; thioindigo pigments; Indoline pigments; isoindolinone pigments; quinophthalone pigments;
Slen pigments; metal complex pigments and the like.

  Examples of the dye derivative are described in JP-A-63-305173, JP-B-57-15620, JP-B-59-40172, JP-B-63-17102, JP-B-5-9469, and the like. What is currently used can be used, These can be used individually or in mixture of 2 or more types. The addition amount of the pigment derivative is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the colorant from the viewpoint of improving dispersibility. Further, from the viewpoint of heat resistance and light resistance, it is preferably 4 parts by mass or less, more preferably 1.5 parts by mass or less, with respect to 100 parts by mass of the colorant.

  In the liquid developer, the appropriate addition amount of the dye derivative varies depending on the type of the colorant (B) to be used, but generally it is in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the colorant (B). It is preferable to use in. Thereby, the dispersion stability of the toner particles is maintained, and the stability of the charging polarity of the toner particles can be maintained. In the liquid developer, it is preferable to use a basic dye derivative since the toner particles have positive chargeability.

(Charge control agent)
The toner particles in the liquid developer may contain a known charge control agent of colorless or light color as long as it does not interfere with the hue as necessary. 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.

(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 Binder resin (A) and colorant (B) are mixed at a ratio of 10 to 60 parts by mass of the colorant (B) in the master batch. Kneading is performed using a shaft extruder, a hot roll, etc., and after cooling, coarse pulverization 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 wax and the like may be added. Further, it is preferable that the toner particle chip has a particle diameter of 5 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 Banbury mixer, a uniaxial or biaxial extruder can be used.

(3) Dry pulverization of toner particles The toner particle chip obtained in (2) is finely pulverized to an average particle size of 100 μm or less. 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, a kryptron, or a hammer 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 also effective to add a polymer dispersant (C) having a function of adsorbing the toner particles. Through the wet pulverization and dispersion steps, the dispersant is adsorbed in the toner particles and stabilized in terms of charging. When performing wet pulverization (dispersion), it is desirable to cool so that the temperature during pulverization does not exceed 60 ° C. If the temperature exceeds 60 ° C., the toner particles may be fused, and the particle size distribution may not be controlled.

  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, a vibrating ball mill, a planetary ball mill, a centrifugal fluidizing mill, and the like, and examples of the medium agitating mill include a tower type pulverizer, a stirring tank type mill, a distribution tank type mill (horizontal type, Vertical type), annular mill and the like. In any of the above apparatuses, miniaturization by wet pulverization is possible, but among them, the use of a medium stirring mill is preferable from the viewpoint of productivity, pulverization ability, control of particle size distribution, and the like. Furthermore, among them, the use of a wet pulverizer classified as a horizontal distribution tank type mill, which is sealed and horizontal, is filled with microbeads and used as a medium (medium), enables precise wet pulverization and dispersion. It is preferable in carrying out. Specific examples include a dyno mill (DYNO-MILL) manufactured by WAB (Shinmaru Enterprises), a sand mill, and the like. 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. Further, since it has a completely sealed structure, there is no loss of balance due to foaming or evaporation of the solvent, and stable pulverization is possible.

 In wet pulverizers, the major factors that determine pulverization include the type of pulverizing media, the particle size of the pulverizing media, the filling rate of the dispersion media in the pulverizer, the solution concentration of the sample to be pulverized, the viscosity, the type of solvent, etc. Can be mentioned. 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 (SiO2 70-80%, NaO 12-16%, etc.), zircon beads (ZrO2 69%, SiO2) depending on the viscosity, specific gravity, required particle size of grinding and dispersion, and the like. 31%), zirconia beads (ZrO2 95% or more), alumina (Al2O3 90% or more), titania (TiO2 77.7%, Al2O3 17.4%), steel balls, etc. can be used. In order to obtain properties, it is preferable to use zirconia beads or zircon beads. The particle diameter (diameter) of the pulverization media can be used in the range of 0.1 mm to 3.0 mm, and in particular, the range of 0.3 to 1.4 mm is preferable. If it is smaller than 0.1 mm, the load in the pulverizer increases, and the toner particles may melt due to heat generation, making pulverization difficult. Moreover, when larger than 3.0 mm, sufficient grinding | pulverization may not be performed. The filling rate of the dispersion medium is preferably 40 to 85% by mass. If it exceeds 85 mass%, the load in the pulverizer increases, and the toner particles may melt due to heat generation, which may make pulverization difficult. Moreover, when it will be less than 40 mass%, a grinding | pulverization efficiency may fall and refinement | miniaturization may become difficult. When the concentration of toner particles in the slurry is high (concentration of 40 to 50% by mass), the filling rate is preferably 40 to 70% 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, toner particles having a particle size of 2 μm or less with respect to all toner particles are contained in an amount of 50% by volume or less, toner particles having a particle size of 1 to 3 μm are contained in an amount of 5 to 60% by volume, and the particle size is 5 μm or more The toner particles are more preferably 35% by volume or less from the viewpoint of development characteristics for obtaining color developability. When the amount of toner particles having a particle size of 2 μm or less is more than 50% by volume, the polymer dispersant (C) may be less adsorbed on the toner particles, and excellent storage stability may not be obtained. Furthermore, in the wet pulverization of toner particles, the pulverizability becomes low, and it may be difficult to control the viscosity of the liquid developer. If the amount of toner particles having a particle size of 5 μm or more exceeds 35% by volume, there may be problems such as insufficient image density and poor color development and color reproducibility. The toner particles having a particle diameter of 1 to 3 μm are preferably contained in an amount of 5 to 60% by volume in order to obtain dispersion stability of the toner particles and excellent storage stability over a long period of time.

  The concentration of the toner particles in the liquid developer is preferably 10 to 40% by mass with respect to 100% by mass of the liquid developer. More preferably, it is 12-35 mass%. When the amount is less than 10% by mass, it is difficult to remove the carrier liquid (D), and the fixability of the toner particles may be lowered. If it exceeds 40% by mass, the viscosity of the liquid developer increases, the mobility of the toner particles decreases, and a sufficient image density may not be obtained. Further, the toner particles may be strongly aggregated and the storage stability may be lowered.

The viscosity (η) of the liquid developer of the embodiment is preferably 3 to 80 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. 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. Can be obtained. If the viscosity (η) is less than 3 mPa · s, the fineness of the image after development is lacking, and if it exceeds 80 mPa · s, the mobility of toner particles during development is reduced and high-speed development cannot be performed, and sufficient image density is obtained. Problems such as inability to occur. The electrical resistivity can be measured in the same manner as in the carrier liquid measurement method described above. If it is 10 ¹⁰ Ω · cm or less, there is a tendency that an electrostatic latent image on the photoreceptor cannot be retained.

  The development process that can be preferably used in the use of the liquid developer is that the liquid developer is supplied to a developing roller made of conductive rubber, and is transferred using an amorphous silicon photoconductor charged with a scorotron charger and exposed to LED. It is preferable to carry out development through an intermediate transfer member after pre-charging. 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 coated paper, all widely used coated papers that have been used for various purposes in the past are all targeted. Specifically, for example, fine coated paper, lightweight coated paper, coated paper, art paper, mat coated paper And cast coated paper, and the thickness and shape thereof are not limited at all. Particularly in coated paper, by using the liquid developer of this embodiment, good image quality can be obtained, and sharp characters and barcodes can be printed. 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.

(Binder Resin Synthesis Example 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.

ビスフェノールＡプロピレンオキサイド付加物：一般式（１）において、Ｒ＝プロピレン基であり、ｘ＝ｙ＝２である化合物。
ビスフェノールＡエチレンオキサイド付加物：一般式（１）において、Ｒ＝エチレン基であり、ｘ＝ｙ＝２である化合物。

Bisphenol A propylene oxide adduct: a compound in which R = propylene group and x = y = 2 in the general formula (1).
Bisphenol A ethylene oxide adduct: A compound in which R = ethylene group and x = y = 2 in the general formula (1).

(Binder Resin Synthesis Example 2)
As in Synthesis Example 1, the polyhydric alcohol and polybasic acid shown in Table 2 and 2 parts of dibutyltin oxide as a catalyst were introduced, nitrogen gas was introduced with stirring, and the reaction system was heated to 180 ° C. The reaction was continued for 7 hours while maintaining the temperature of. 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 less, and polycondensation was stopped to obtain a binder resin 2 which was a polyester resin.

(Binder Resin Synthesis Example 3)
The obtained binder resin 1 was put in an equal amount of toluene and heated to be dissolved. Nitrogen gas is introduced with stirring, and the mixture is further heated to the boiling point of toluene. A mixture containing styrene monomers, acrylic acid, acrylic esters, and di-t-butyl peroxide as a polymerization initiator shown in Table 3 Solution polymerization was performed while dropping the solution over 2 hours. 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 to 180 degreeC and toluene was removed, and the binder resin 3 containing a polyester resin and a styrene-acryl copolymer resin was obtained.

  Table 4 shows the physical property values of the obtained binder resins 1 to 3.

  As the binder resin 4, styrene acrylic resin FCA-201-PS manufactured by Fujikura Kasei Co., Ltd. was used.

(Synthesis example 1 of polymer dispersant)
(Synthesis example 1 of polymer dispersant)
A reaction vessel equipped with a nitrogen gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 90.1 parts of Exol D110 (manufactured by ExxonMobil) and replaced with nitrogen gas. The reaction vessel is heated to 110 ° C., 20.0 parts of N, N-dimethylaminoethyl methacrylate, 60.0 parts of stearyl methacrylate, 20.0 parts of butyl acrylate, and 2,2′-azobis as a polymerization initiator. A mixture of 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 polymeric dispersant 1 was about 6940. 1 g of this was sampled, heated and dried at 180 ° C. for 20 minutes to measure the nonvolatile content, and Exol D110 was added so that the nonvolatile content of the polymer dispersant solution was 50%. From this, a 50% nonvolatile solution of the polymer dispersant 1 was obtained.

(Synthesis example 2 of polymer dispersant)
90.1 parts of Exol D110 (naphthenic hydrocarbon solvent, manufactured by ExxonMobil) was charged into the same reaction vessel as in Synthesis Example 1 of the polymer dispersant, and replaced with nitrogen gas. The reaction vessel is heated to 110 ° C., 20.0 parts of N, N-dimethylaminoethyl methacrylate, 60.0 parts of stearyl methacrylate, 20.0 parts of polyethylene glycol (addition number of ethylene oxide: 9) monomethacrylate monomethyl ether Further, a mixture containing 9.0 parts of 2,2′-azobis (2-methylpropionic acid) dimethyl (V-601 (manufactured by Wako Pure Chemical Industries)) as a polymerization initiator was added dropwise over 2 hours to conduct a polymerization reaction. It was. 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, Ltd.) was added, and the reaction was further continued at 110 ° C. for 1 hour. Got. The weight average molecular weight (Mw) of the polymer dispersant 2 was 7,000. 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 2 solution such that the nonvolatile content of the polymer dispersant solution was 50 mass%. As a result, a 50% by mass solution of the polymer dispersant 2 with a nonvolatile content was obtained.

The amine value and weight average molecular weight of each polymer dispersant were as shown in Table 5.

(Coloring agent)
Cyan colorant C.I. I. Pigment Blue 15: 3 (copper phthalocyanine blue)
Lionol Blue FG7919 (Toyo Color)

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

(Carrier liquid)
Isopar M Isoparaffin hydrocarbon (manufactured by ExxonMobil)
Dry point: 254 ° C. Aniline point: 91 ° C. Density: 0.789 g / cm ³ Kinematic viscosity: 3.77 mm ² / s
IP Solvent 2028 Isoparaffinic hydrocarbon (made by Idemitsu Kosan Co., Ltd.)
Dry point: 262 ° C. Aniline point: 89 ° C. Density: 0.790 g / cm ³ Kinematic viscosity: 3.50 mm ² / s
Exol D110 Naphthenic hydrocarbon (manufactured by ExxonMobil)
Dry point: 265 ° C. Aniline point: 83 ° C. Density: 0.808 g / cm ³ Kinematic viscosity: 3.43 mm ² / s
AF Solvent No. 5 Naphthenic hydrocarbon (manufactured by JX Nippon Oil & Energy Corporation)
Dry point: 300 ° C. Aniline point: 92 ° C. Density: 0.810 g / cm ³ Kinematic viscosity: 5.50 mm ² / s
Exol D30 Naphthenic hydrocarbon (manufactured by ExxonMobil)
Dry point: 163 ° C. Aniline point: 65 ° C. Density: 0.767 g / cm ³ Kinematic viscosity: 1.04 mm ² / s
KF-96-2CS Dimethyl silicone oil (manufactured by Shin-Etsu Silicone)
Soybean white oil (Nisshin Oilio)

(Antioxidant)
Antage SP styrenated phenol (manufactured by Kawaguchi Chemical Co., Ltd.)
Antage BHT 2,6-di-t-butyl-p-cresol (manufactured by Kawaguchi Chemical Co., Ltd.)
Adeka Stab AO-50 3- (4-Hydroxy-3,5-di-t-butylphenyl) propionic acid octadecyl (manufactured by ADEKA)
Antage OD Diphenylamine derivative (manufactured by Kawaguchi Chemical Industry Co., Ltd.)
Antage LDA Diphenylamine derivative (manufactured by Kawaguchi Chemical Industry Co., Ltd.)
JP-310 tridecyl phosphite (Johoku Chemical Industry Co., Ltd.)
ADK STAB AO-40 6,6'-di-t-butyl-4,4'-butylidene-m-cresol (manufactured by ADEKA)
Antage DDA Diphenylamine derivative (manufactured by Kawaguchi Chemical Industry Co., Ltd.)
JPE-10 bis (decyl) pentaerythritol diphosphite (manufactured by Johoku Chemical Industry Co., Ltd.)

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 cyan toner pulverized product 1 having an average particle diameter of 7.0 μm.

Further, cyan toner pulverized product 1 25 parts by mass Isopar M 71.5 parts by mass Polymer Dispersant 1 3 parts by mass Antage SP 0.5 parts by mass are thoroughly weighed and mixed, and cyan toner is added to the Isopar M solution. The pulverized product 1 was dispersed (slurry concentration was 25% by mass). The slurry in which the toner particles 1 are dispersed is subjected to a circulation operation for 60 minutes using a wet pulverizer which is a medium stirring mill, Dino Mill Multilab (manufactured by Shinmaru Enterprises Co., Ltd., capacity 1.4 L), and is 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} 60 minutes of wet pulverization, the slurry was taken out and passed through a mesh having a mesh size of 33 μm (manufactured by SUS304) to obtain liquid developer 1. When the particle size distribution was confirmed, the average particle size (D50) was 2.6 μm. The viscosity (η) was 10.0 mPa · s.

 Cyan toner pulverized products and liquid developers were prepared using the raw materials shown in Table 6 and Table 7 in the same manner as in Example 1. The particle size was measured using a Nikkiso Co., Ltd. laser diffraction / scattering particle size analyzer Microtrac HRA, the solvent was Exol D80 (Exxsol ™) (Exxon Mob48il Corporation), and 23 ° C. and 50% RH. The average particle diameter (D50) is a value of a cumulative 50 percent diameter, and the viscosity (η) of the liquid developer is measured with 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., a 1 ° 34 ′ cone was set in the TV-22 type viscosity form, and after 1 minute at 20 rpm. The viscosity of was measured.

  Table 8 shows the evaluation of the solubility between the antioxidant (E) and the carrier liquid (D) used in Examples and Comparative Examples, and the compatibility between the antioxidant (E) and the binder resin (A). Results are shown.

(Solubility of antioxidant in carrier liquid)
A 10% by mass antioxidant solution is prepared with respect to the carrier liquid, stirred at 50 ° C. for 1 hour, cooled to 25 ° C., and the state of the solution after 2 hours is determined by visual judgment.
◯: There is no undissolved material and it is transparent.
X: There exists an undissolved substance and it precipitates or becomes cloudy.

(Compatibility of antioxidant and resin)
A 10% by weight MEK solution of the binder resin is prepared, and an antioxidant is added in the same amount as the binder resin. After confirming dissolution of the antioxidant, it is applied to a glass plate with a wet film thickness of 20 μm. After drying MEK in an oven at 40 ° C. for 30 minutes, the state of the coating film at 25 ° C. was visually judged.
◯: Transparent coating film ×: Cloudy coating film

  In the actual image test, a commercially available liquid developing copier (Savin 870: manufactured by Sabin Co., Ltd.) was used, and an amorphous silicon photoconductor and a scorotron charger were used under an environmental condition of 23 ° C./50% RH. The body surface potential was set to +450 to 500 V, the residual potential was +50 V or less, the developing roller bias was set to +250 to 450 V, and 3000 image tests were performed from the initial stage. The 3000th image was used for evaluation of image quality, image density, and fixing rate. The paper was OK top coat made by Oji Paper, and the thermocompression bonding was performed under the conditions of a speed of 30 m / min and 160 ° C.

(Image density)
The image density was measured with a Gretag Macbeth densitometer (D-196). Here, it is practically preferable that the density value of cyan is 1.4 or more. More preferably, it is 1.5 or more.
◎: Density value 1.5 or more ○: Density value 1.4 or more and less than 1.5 Δ: Density value 1.3 or more and less than 1.4 ×: Density value less than 1.3

(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 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.
◎: 90% or more ○: 80% or more and less than 90% △: 70% or more and less than 80% ×: less than 70%

(Image quality)
Regarding the image quality, whether or not image streaks are generated due to adhesion of oxide to the photoconductor was visually evaluated for a solid portion of 10 cm × 10 cm.
◯: No image streak occurred ×: Image streak occurred

(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 and evaluated at a rate increased from the value before the start of the test.

Average particle size (D50)
○: Average particle size after test (D50) / average particle size before test (D50) is less than 1.2 ×: Average particle size after test (D50) / average particle size before test (D50) is 1. 2 or more

Viscosity (η)
○: Viscosity after test (η) / viscosity before test (η) is less than 1.4 ×: viscosity after test (η) / viscosity before test (η) is 1.4 or more

  Detailed physical property values and test results of the liquid developer are shown in Table 9.

 Examples 1 to 8 have a good particle size and viscosity, and are excellent in storage stability, printing density, and fixability. Further, there is no image streak in continuous printing, and excellent image quality is obtained. Since Comparative Examples 1 to 3 have poor solubility of the antioxidant (E) in the carrier liquid (D), the storage stability of the liquid developer is poor. Since Comparative Example 4 does not contain the antioxidant (E), adhesion of oxide to the photoreceptor is observed during continuous printing, and image streaks are generated. Since Comparative Example 5 does not contain a polyester resin in the binder resin (A), excellent pigment dispersibility cannot be obtained, and printing density and storage stability are poor. In Comparative Example 6, the dry point of the carrier liquid (D) is high and the fixability is poor. In Comparative Example 7, the dry point of the carrier liquid (D) is low, the drying on the printing roller such as the photoreceptor is remarkable, and the printing density is inferior. In Comparative Examples 8 and 9, since the carrier liquid (D) is not an aliphatic hydrocarbon, the toner particles are inferior in dispersibility and therefore in storage stability. Further, since the liquid developer has a high viscosity and a large particle diameter, a good printing density cannot be obtained.

The liquid developer of the present invention is excellent in continuous printing stability, fixing property, image density, and storage stability, and is an electrophotographic copier, printer, and the like that can form an image using electrophotography, electrostatic recording method, etc. It can be preferably used as a liquid developer used for developing an electrostatic latent image in an on-demand printing machine.

Claims (7)

A liquid developer comprising at least a binder resin (A), a colorant (B), a polymer dispersant (C), a carrier liquid (D), and an antioxidant (E),
The binder resin (A) includes at least a polyester resin,
The carrier liquid (D) comprises an aliphatic hydrocarbon having a dry point in the distillation range of 180 ° C. to 280 ° C., and the antioxidant (E) is 10% at 25 ° C. with respect to the carrier liquid (D). A liquid developer, which is an antioxidant that dissolves by mass% or more.
The liquid developer according to claim 1, wherein the antioxidant (E) is compatible with the binder resin (A) at 25 ° C.
The liquid developer according to claim 1, wherein the binder resin (A) further contains a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin.
The liquid developer according to claim 1, wherein the antioxidant (E) is contained in an amount of 0.01 to 5.0% by mass in the liquid developer.
The liquid developer according to any one of 1 to 4, wherein the antioxidant (E) contains at least a phenolic antioxidant.
The polymer dispersant (C) includes at least an ethylenically unsaturated monomer (c-1) having an amino group and an ethylenically unsaturated monomer (c-) containing an alkyl group having 9 to 24 carbon atoms. 2), and
6. The liquid developer according to claim 1, wherein the polymer dispersant (C) has an amine value of 5 to 150 mgKOH / g.
A printed matter obtained using the liquid developer according to claim 1.