JP2016142789A - Liquid developer set and printed matter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer excellent in repeated transfer rate and color reproducibility.SOLUTION: The liquid developer set consists of at least 4 colors of yellow, magenta, cyanogen and black. Each liquid developer of yellow, magenta, cyanogen and black includes a binder resin (A), a colorant (B), a polymer dispersant (C) and a carrier liquid (D). Each binder resin (A) independently includes a polyester resin; each polymer dispersant (C) independently includes at least a polymer dispersant formed by polymerizing an ethylenically unsaturated monomer (c-1) having an amino group and an ethylenically unsaturated monomer (c-2) including a C9-24 alkyl group and having an amine value of 5-150 mgKOH/g; and each carrier liquid (D) is independently aliphatic hydrocarbon.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid developer set and a 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

  Usually, when color image formation is performed using a liquid developer, for example, a liquid developer of four basic processes of Y (yellow), M (magenta), C (cyan), and Bk (black) is transferred, dried, Further, by fixing, an image having excellent color reproducibility can be formed. In addition, an intermediate color such as violet or green can be used to form an image with further excellent color reproducibility. Until now, studies have been made to obtain a wide color reproduction region even in dry powder toners (see, for example, Patent Documents 1, 2, and 3).

  In general, a full-color image in four colors has a specific hue of single colors Y, M, and C, plus red with yellow and magenta, blue violet with magenta and cyan, and green with cyan and yellow. The color reproduction area is expanded and an image having excellent color reproducibility can be obtained. This multi-color secondary color provides excellent color reproducibility by transferring the post-printing toner particles onto the pre-printed toner layer on the recording medium, but the transfer property of the post-printing toner particles is excellent. If it is insufficient, sufficient color reproducibility cannot be obtained. In particular, in an image forming apparatus using a liquid developer, since the toner particles are present in the carrier liquid as compared with the dry powder toner, the charging efficiency to the toner particles is low, and moreover Even if the carrier liquid remaining in the pre-printed toner layer reduces the transferability of the toner particles for post-printing and has excellent transferability and color reproducibility in a single-color image, a composite image of secondary or higher colors is obtained. However, there was a problem that sufficient color reproducibility could not be obtained. In contrast, studies have been made to increase the color reproduction area by increasing the colorant concentration in the toner particles. However, the fixing property to the recording medium is deteriorated, and the toner particles are transferred to the non-image area. There was a problem that "phenomenon" occurred.

  Patent Documents 4 and 5 disclose developer sets using specific pigments, resins, and the like, but there is room for improvement in order to satisfy excellent transferability and color reproducibility.

JP 2001-312102 A JP 05-72810 A Japanese Patent No. 5109404 JP 2011-95585 A Japanese Patent Laid-Open No. 10-254185

As described above, in an image forming apparatus using a liquid developer, there is room for improvement in obtaining excellent transferability and color reproducibility, and a liquid developer set that solves this problem is demanded.

  Accordingly, an object of the present invention is to provide a liquid developer set having excellent transferability and color reproducibility. Moreover, it aims at providing the printed matter obtained using this.

  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.

That is, an embodiment of the present invention is a liquid developer set consisting of at least four colors of yellow, magenta, cyan, and black,
Each of the yellow, magenta, cyan, and black liquid developers includes a binder resin (A), a colorant (B), a polymer dispersant (C), and a carrier liquid (D).
The binder resin (A) independently includes a polyester resin (a-1),
The colorant (B) is a yellow liquid developer, C.I. I. Including any of CI Pigment Yellow 12, 13, and 14;
The magenta liquid developer is C.I. I. Pigment Red 57: 1, and C.I. I. Pigment red 122, 146, 147, 150, 269, and C.I. I. Including any one of Pigment Violet 19,
The cyan liquid developer is C.I. I. Including any of CI Pigment Blue 15: 3 and 15: 4,
The black liquid developer contains carbon black, and C.I. I. Any one of CI Pigment Blue 15: 3, 15: 4, and Pigment Violet 23,
The polymer dispersant (C) is independently an ethylenically unsaturated monomer having an amino group (c-1) and an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms ( c-2) and a polymer dispersant having an amine value of 5 to 150 mgKOH / g.
The present invention relates to a liquid developer set wherein the carrier liquid (D) is independently an aliphatic hydrocarbon.

  In the embodiment of the present invention, the binder resin (A) further contains at least one selected from a styrene resin, an acrylic resin, and a styrene-acrylic copolymer resin. Regarding the set.

  In the embodiment of the present invention, the softening temperature of the binder resin (A) is 80 to 140 ° C., and the weight average molecular weight (Mw) is 2000 ≦ Mw ≦ 100,000. About.

  In addition, the embodiment of the present invention relates to the above liquid developer set, wherein the carrier liquid (D) is an aliphatic hydrocarbon having a dry point in the distillation range of 200 ° C. to 280 ° C.

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

  According to the embodiment of the present invention, it is possible to provide a liquid developer set having excellent transferability and color reproducibility, and a printed matter obtained using the liquid developer set.

FIG. 1 shows a gamut of Examples 1 to 5. FIG. 2 shows the gamut of Example 2 and Examples 6-8. FIG. 3 shows gamuts of Example 2 and Comparative Examples 1 to 3. FIG. 4 is a gamut of red regions of Examples 1 to 8 and Comparative Examples 1 to 3. FIG. 5 is a gamut of the magenta region of Examples 1 to 8 and Comparative Examples 1 to 3. FIG. 6 is a gamut in the blue violet region of Examples 1-8 and Comparative Examples 1-3. FIG. 7 shows gamuts of green regions of Examples 1 to 8 and Comparative Examples 1 to 3.

Hereinafter, the present invention will be described in detail.
In the liquid developer according to the embodiment of the present invention, at least for each of the yellow, magenta, cyan, and black liquid developers, the colorant (B) is used, and the yellow liquid developer is C.I. I. Pigment Yellow 12, 13, and 14 and the magenta liquid developer is C.I. I. Pigment Red 57: 1, and C.I. I. Pigment red 122, 146, 147, 150, 269, and C.I. I. Pigment Violet 19 and the cyan liquid developer is C.I. I. Pigment Blue 15: 3 and 15: 4, the black liquid developer contains carbon black, and C.I. I. A major feature is that any one of CI Pigment Blue 15: 3, 15: 4, and Pigment Violet 23 is included.

  The reason is not clear, but by using these colorants, when forming an overlaid image on a substrate, good overtransferability of the liquid developer can be obtained, and excellent color reproducibility can be obtained. Can do. This is presumably due to chemical interactions derived from the structure of the colorant.

  The binder resin (A) includes at least a polyester resin (a-1), and the polymer dispersant (C) includes at least an ethylenically unsaturated monomer having an amino group (c-1) and a carbon number. A toner of each color when superposed images are formed by polymerizing an ethylenically unsaturated monomer (c-2) containing 9 to 24 alkyl groups and having an amine value of 5 to 150 mgKOH / g The interaction between particles becomes stronger, and good overlay transfer and color reproducibility can be obtained.

  Hereinafter, the binder resin (A), the colorant (B), the polymer dispersant (C), the carrier liquid (D) 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 anhydride thereof; succinic acid, n-dodecenyl succinic acid or anhydride 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. To control the molecular weight, softening temperature, etc. of the polyester resin (a-1), the kind of alcohol component and carboxylic acid to be reacted, the molar ratio, The reaction temperature, reaction time, reaction pressure, catalyst, etc. may be adjusted. Furthermore, it is also possible to use a commercial item as a polyester resin. For example, there are Diacron ER-502 and Diacron ER-508 (both manufactured by Mitsubishi Rayon Co., Ltd.).

  Furthermore, in order to improve fixability and grindability and to obtain good color developability, the binder resin (A) is a polyester resin (a-1), a styrene resin, an acrylic resin, and a styrene-acrylic copolymer resin. It is preferable to include at least one resin (a-2) selected from the group consisting of (hereinafter also simply referred to as 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, to control the molecular weight and softening temperature of a styrene-acrylic copolymer resin, the types and molar ratios of the styrene monomer, (meth) acrylic acid and (meth) acrylic acid esters, and further the reaction temperature, reaction What is necessary is just to adjust time, reaction pressure, a polymerization initiator, a crosslinking agent, etc. Furthermore, it is also possible to use a commercial item as a styrene-acrylic copolymer resin. For example, there are ALMATEX CPR100, CPR200, CPR300, CPR600B (Mitsui Chemicals).

In order to obtain a binder resin (A) that is more uniformly dispersed by mixing the polyester resin (a-1) and the resin (a-2), the polyester resin (a-1) and the resin (a-2) 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 is 1 or less, the dispersibility of the colorant (B) and the pulverization property of the toner particles are improved, and the color developability and storage stability as a liquid developer are improved.

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

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

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

  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 exceeds 2, the offset resistance is increased and the non-offset region is widened to improve the low temperature fixability. When Mw / Mn is less than 20, the pulverizability of the toner particles becomes high, a sufficient image density is obtained, and the image characteristics are improved, such as high color developability.

  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. 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.

  A 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.

(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 higher than 3 mgKOH / g, the polymer dispersant (C) is easily adsorbed to the binder resin (A), the dispersion stability of the toner particles is improved, and the storage stability of the liquid developer is improved. . When the acid value is lower than 70 mgKOH / g, the chargeability of the toner particles is high, and sufficient image density and good color development / color reproducibility can be obtained. 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.

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

(Colorant (B))
As the colorant (B), the following organic pigments of yellow, magenta, cyan, and black; carbon black and the like are excellent in pigment dispersibility with respect to the binder resin (A), and the printing quality in a single color is good. In addition, since it is excellent in the overlap transfer rate, it is 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).

  Examples of yellow colorants include C.I. which is a condensed azo compound. I. Any one of CI Pigment Yellow 12, 13, and 14 organic pigments. The said organic pigment may be used independently and may be used in mixture of 2 or more types. The following organic pigments can be mixed and used as long as the quality of the organic pigment is not impaired. Examples of yellow organic pigments that may be mixed 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 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 138, 139, 147, 150, 155, 168, 174, 176, 180, 185, 181 and 191 are preferably used.

  Examples of the magenta colorant include C.I. I. Pigment Red 57: 1, and C.I. I. Pigment red 122, 146, 147, 150, 269, and C.I. I. Any of CI Pigment Violet 19 is included. C. I. These organic pigments used in combination with Pigment Red 57: 1 may be used singly or in combination of two or more. C. I. Pigment Red 57: 1, C.I. I. Pigment red 122, 146, 147, 150, 269, and C.I. I. It is preferable to use the pigment violet 19 in the range of 5 to 100% by weight. Furthermore, as long as quality is not impaired, organic pigments other than the above can be mixed and used. Examples of magenta organic pigments that may be mixed include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone, quinacridone compounds, lake compounds such as rhodamine lakes, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylenes. A compound is used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 81, 81: 1, 81: 2, 81: 3, 81: 4, 144, 166, 169, 177, 184, 185, 202, 206, 209, 220, 221, 254, 255, 268, etc., C.I. I. Pigment Violet 1 or the like is preferably used.

  Examples of cyan colorants include C.I. I. Any one of CI Pigment Blue 15: 3 and 15: 4. In addition, organic pigments other than those described above can be mixed and used as long as the quality of the organic pigment is not impaired. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 6, 60, 62, 66, etc. are preferably used. 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. In particular, a green pigment, C.I. I. Halogenated phthalocyanine compounds such as CI Pigment Green 7 and 36 are preferred.

  Examples of black colorants include carbon black, and C.I. I. Pigment Blue 15: 3, 15: 4, and Pigment Violet 23 are included. For carbon black, C.I. I. Pigment Blue 15: 3, 15: 4, and Pigment Violet 23 are preferably included in an amount of 1 to 10% by weight. Furthermore, organic black pigments such as perylene black and organic black dyes such as nigrosine dyes and azo metal complex dyes can be mixed and used as long as the quality is not impaired. 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 preferred because they have the effect of reducing the fog phenomenon (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.

  The content of the colorant (B) contained in the toner particles varies depending on the type of the binder resin (A) used, but usually the mass ratio of the binder resin (A) to the colorant (B) [binder. Resin (A) / Colorant (B)] is 2-15, preferably 3-8. When the mass ratio exceeds 2, the ratio of the binder resin (A) to the colorant (B) increases, the toner particles have good film-forming properties, and the fixing property to the base material is improved. On the other hand, when the mass ratio is 15 or less, the hot offset resistance is improved, and the coloring power and color developability as toner particles are further improved.

(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 an ethylenically unsaturated monomer (c-2) having at least an ethylenically unsaturated monomer (c-1) having an amino group and an alkyl group having 9 to 24 carbon atoms. And a copolymer having an amine value of 5 to 150 mgKOH / g. By using the copolymer, the dispersibility, the overlay transfer property, and the fixing property are improved. A suitable polymerization method for the polymer dispersant (C) is solution polymerization of a normal acrylic resin. The ratio of the ethylenically unsaturated monomer having an amino group (molar ratio of the charged amount) is preferably 1 to 50%, more preferably 5 to 40%, and most preferably 10 to 35%. . The ratio of the ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms is preferably 50 to 99%, more preferably 60 to 95%, and most preferably 65 to 90%.

  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 (c-1) having an amino group increases the adsorption rate of the polymer dispersant (C) to the toner particles, and contributes to a stable image and excellent storage stability over a long period of time. The amino group in the ethylenically unsaturated monomer 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 5 to 150 mgKHO / g, preferably 30 to 100 mgKHO / g. When the amine value is 5 mgKHO / g or more, the adsorptivity to the toner particles is high, and the pulverization property by wet pulverization is improved. Furthermore, during storage for a long period of time, aggregation of toner particles is suppressed, and a change in viscosity and average particle diameter of the liquid developer is small, so that good storage stability can be obtained. When the amine value is 150 mgKHO / g or less, the chargeability of the toner particles becomes high, the toner particles are easily transferred to the substrate, and a good image density can be obtained. Furthermore, the solubility in the carrier liquid is increased, and the grindability is improved. The amine value of the polymer dispersant (C) is the total amine value (mgKHO / g) measured according to the method of ASTM D2074.

  The ethylenically unsaturated monomer (c-2) containing an alkyl group having 9 to 24 carbon atoms increases the solubility of the alkyl group having 9 to 24 carbon atoms in the carrier liquid (D), and is pulverized in wet pulverization. Improve sexiness. Furthermore, during storage for a long period of time, aggregation of toner particles and increase in the viscosity of the liquid developer are suppressed, and an excellent storage stability effect is exhibited. When the carbon number of the alkyl group is larger than 9, the solubility in the carrier liquid (D) is high, and the dispersion stability and the storage stability are increased. When the carbon number of the alkyl group is less than 24, when the liquid developer is fixed to the substrate, the alkyl group does not hinder the contact and coalescence of the toner particles, and the fixing property is not lowered. Furthermore, the chargeability of the toner particles is increased, the toner particles are easily transferred to the substrate, and a sufficient image density can be obtained.

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

(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′-azobis (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 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 the first method, the carrier liquid (D) used in the liquid developer 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)
In addition, examples of the unsaturated compound that may be included as the polymerizable monomer include an ethylenically unsaturated monomer represented by the following general formula (2). In the polymerization of the polymer dispersant (C), the use of the ethylenically unsaturated monomer represented by the general formula (2) is effective in improving the fixability of the liquid developer.
General formula (2)

_{CH 2 = C (R1) COO} (AO) nR2

(Wherein R 1 represents a hydrogen atom or —CH ₃ ;
R2 represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms,
n represents an integer of 1 to 200,
A represents an alkylene group having 2 to 4 carbon atoms. )

  By including the ethylenically unsaturated monomer represented by the general formula (2), the compatibility with the binder resin (A) is improved, and in the fixing process, the molten state of the toner particles is improved, and the substrate Improves the fixing property. Further, it is possible to suppress the cold offset phenomenon in which the toner particles that are insufficiently melted adhere to the thermocompression roller and transfer to the next paper. The ethylenically unsaturated monomer represented by the general formula (2) is, for example, ring-opening polymerization of ethylene oxide with an alkyl alcohol, and then the obtained reaction product is transesterified with methyl (meth) acrylate. Alternatively, it can be obtained by reacting with (meth) acrylic acid chloride.

  In the said General formula (2), an alkylene oxide group (AO) is a C2-C4 alkylene oxide group, for example, an ethylene oxide group, a propylene oxide group, or a butylene oxide group is mentioned. Moreover, the alkylene oxide group from which carbon number differs may exist in the same monomer.

  The number (n) of alkylene oxide groups is an integer of 1 to 200, preferably an integer of 1 to 30. When it is 200 or less, sufficient compatibility with the above-described ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms in the molecule can be obtained. R2 is hydrogen or a hydrocarbon group having 1 to 22 carbon atoms. When the number of carbon atoms is 22 or less, raw materials are easily available and practical. As the hydrocarbon group having 1 to 22 carbon atoms, a substituted or unsubstituted group can be selected, an unsubstituted group is preferable, and an unsubstituted alkyl group is preferable. As the unsubstituted alkyl group, those having a branch and those having no branch can be used. Two or more types of ethylenically unsaturated monomers represented by the general formula (2) may be used in combination. R2 is more preferably hydrogen or a hydrocarbon group having 1 to 18 carbon atoms.

  Examples of the compound having an alkylene oxide chain include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, Poly (ethylene glycol-tetramethylene glycol) mono (meth) acrylate, poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate, polyethylene glycol mono (meth) acrylate monomethyl ether, polyethylene glycol mono (meth) acrylate monobutyl ether, Polyethylene glycol mono (meth) acrylate monooctyl ether, polyethylene glycol mono (meth) Acrylate monobenzyl ether, polyethylene glycol mono (meth) acrylate monophenyl ether, polyethylene glycol mono (meth) acrylate monodecyl ether, polyethylene glycol mono (meth) acrylate monododecyl ether, polyethylene glycol mono (meth) acrylate monotetradecyl ether , Polyethylene glycol mono (meth) acrylate monohexadecyl ether, polyethylene glycol mono (meth) acrylate monooctadecyl ether, poly (ethylene glycol-propylene glycol) mono (meth) acrylate octyl ether, poly (ethylene glycol-propylene glycol) mono ( (Meth) acrylate octadecyl ether, poly (ethylene glycol-pro Glycol) mono (meth) acrylate nonylphenyl ether and the like.

  Furthermore, examples of 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.

(Average molecular weight)
The weight average molecular weight (Mw) of the polymer dispersant (C) is not limited to a specific range, but in consideration of dispersibility and grindability when the toner particles are wet-dispersed, gel permeation chromatography (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 0.5-5 mass parts. When the amount is 0.1 part by mass or more, the dispersibility and pulverization properties of the toner particles are improved, and the storage stability is improved. When the addition amount is 10 parts by mass or less, the chargeability of the toner particles can be easily obtained, and a sufficient image density can be obtained by increasing the transfer rate. Further, the toner particles have a high film forming property and the fixing property is improved. When the toner particles contain the polymer dispersant (C), the above range is a range including the amount of the polymer dispersant (C) contained in the toner particles.

(Other dispersants)
As the dispersant, a dispersant conventionally used for a liquid developer may be used. Specifically, fatty acid metal salts such as cobalt naphthenate, zinc naphthenate, cobalt octylate and zirconium octylate, titanate coupling agents of organic titanates such as lecithin and titanium chelates, alkoxy titanium polymers, polyhydroxy titanium carboxylates Examples include compounds, titanium alkoxides, succinimide compounds, polyimine compounds, fluorine-containing silane compounds, and pyrrolidone compounds. 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.

(Carrier liquid (D))
The carrier liquid (D) used for the liquid developer is an aliphatic hydrocarbon. Aliphatic hydrocarbons have lipophilicity and are chemically stable and insulating. In particular, a desired toner particle diameter can be obtained by obtaining good storage stability and good dispersibility of toner particles. Examples of the aliphatic hydrocarbon include linear paraffinic hydrocarbons, isoparaffinic hydrocarbons, naphthenic hydrocarbons, and the like. Among these, paraffinic hydrocarbons with very little residual aromatic hydrocarbon are preferable. Further, 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 to 360 ° C, and more preferably in the range of 200 ° C to 280 ° C. When the dry point is 180 ° C. or higher, it is possible to maintain good transferability without drying the liquid developer on a roller such as a photoreceptor in the printing process, and an excellent image density can be obtained. In addition, when the dry point is 360 ° C. or lower, the carrier liquid (D) can be easily removed, so that sufficient fixability can be obtained. Furthermore, the viscosity of the liquid developer is kept low, the toner particle mobility during development is good, and it is suitable for high-speed development. Here, the dry point in the distillation range is determined by the method defined by ASTM D86, ASTM D1078, and JIS K2254.

  Moreover, it is preferable to use a carrier liquid (D) having a Kauri-butanol value (KB value: ASTM D1133) of 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 is 30 or less, or the aniline point is 60 ° C. or more, the solubility as a solvent is low, and the carrier liquid does not dissolve the toner particles. It is possible to prevent the problem that the carrier liquid becomes high and the base material such as paper is soiled. When the aniline point is 105 ° C. or lower, the compatibility with the dispersant and additives added when dispersing the toner particles in the carrier liquid is high, the dispersibility is improved, and a sufficient image density can be obtained. .

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

Furthermore, the density (JIS K2249) of the carrier liquid (D) at 15 ° C. is preferably in the range of 0.70 to 0.90 g / cm ³ . More preferably, it is the range of 0.75-0.85 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) is preferably in the range of kinematic viscosity (ASTM D445) 1 to 25 mm ² / s. Especially preferably, it is the range of 2-15 mm < ² > / s. This range is preferable in that the charged particles can be moved at the time of the phenomenon, and the carrier liquid is sufficiently volatile so that the carrier liquid can be easily removed from the medium on which the final image is formed in the fixing step. . When the kinematic viscosity is higher than 1 mm ² / s, the liquid developer has a high viscosity, so that the transfer property to the developing roller is good, and a sufficient image density can be obtained. Further, the movement of toner particles after development is suppressed, and the fineness of the image is improved. If the kinematic viscosity is lower than 25 mm ² / s, the toner particles have good fluidity and are easily electrophoresed, so that a sufficient image density can be obtained. Furthermore, it has a high permeability to a substrate such as paper, and it becomes easy to remove the carrier liquid when the toner particles are fixed, and a sufficient fixing property can be obtained. In particular, the fixability in a superimposed image is greatly improved.

Specifically preferred carrier liquids (D) are branched paraffin solvent mixtures, in particular isoparaffinic, such as the trade names “Isopar ^™ M” (ExxonMobil), “IP Solvent 2028” (Idemitsu Kosan). Hydrocarbons or naphthenic hydrocarbons such as “Exol D110”, “Exsol D130” (Exxsol ™) (ExxonMobil), “AF Solvent No. 4”, “AF Solvent No. 5” (JX Nippon Oil & Energy) It is preferable.
It is preferable that it is 60-90 mass% with respect to 100 mass% of carrier liquid (D) liquid developers. When the content is 60% by mass or more, good fluidity of the liquid developer is obtained, and when the content is 90% by mass or less, good fixability and printing density are obtained.

(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 pulverization property 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 (3).
General formula (3)

P-Ln

(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 and copper phthalocyanine halide; aminoanthraquinone; Anthraquinone pigments such as anthrapyrimidine, flavantron, indanthrone, pyranthrone, violanthrone; quinacridone pigments; dioxazine pigments; perinone pigments; perylene pigments; thioindigo pigments; isoindolinone pigments; Pigments, selenium pigments, metal complex pigments, and the like.

  As the dye derivative, for example, those described in JP-A-63-305173, JP-B-59-40172, JP-B-63-17102, JP-B-5-9469 and the like can be used, These can be used alone or in admixture of two or more. The addition amount of the pigment derivative varies depending on the type of the colorant (B) to be used, but from the viewpoint of dispersion stability, it is preferably 0.5 part by mass with respect to 100 parts by mass of the colorant (B). As mentioned above, More preferably, it is 1 mass part or more. Further, from the viewpoint of heat resistance and light resistance, it is preferably 4 parts by mass or less, and more preferably 1.5 parts by mass or less with respect to 100 parts by mass of the colorant (B).

(Charge control agent)
The toner particles in the liquid developer may contain a 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.

  As the positive charge control agent, a quaternary ammonium salt compound, a quaternary ammonium salt, an organic tin oxide, a diorganotin borate, an electron donating substance such as a polymer having an amino group, or the like may be used alone or in combination of two or more. it can. Triarylmethane dyes can also be used as positive charge control agents. Further, instead of using the above charge control agent, a resin charge control agent can also be used. Examples of the resin charge control agent include a copolymer of acryloylamino-2-methyl-1-propanesulfonic acid and a vinyl monomer such as styrene or acrylate ester. Since these are colorless and transparent, they are suitable for use in color toners. Further, the resin charge control agent is usually added in an amount of preferably 1.0 to 20 parts by mass, more preferably 2.0 to 8 parts by mass with respect to 100 parts by mass of the binder resin (A).

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

(1) Preparation of Colored Master Batch for Toner Particles 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 or 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 (dispersion) step, the dispersant is adsorbed on 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 50 ° C. When the temperature is 50 ° C. or lower, the particle size distribution can be controlled without causing fusion of the toner particles.

  As a wet pulverizer that can be used for wet pulverization of toner particles, a pulverization medium is used, and examples thereof include a container drive medium mill and a medium stirring mill. Examples of the container drive medium mill include a rolling ball mill, a planetary ball mill, and a centrifugal fluidization mill. As a medium agitation mill, a tower pulverizer, an agitation 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 and evaporation of the solvent, and stable pulverization is possible.

  Major factors that determine the pulverization property in the wet pulverizer include the type and particle size of the pulverizing medium, the filling rate of the dispersion medium in the pulverizer, the solution concentration of the sample to be pulverized, the viscosity, the type of solvent, and the like. 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 to 80% by mass, NaO 12 to 16% by mass, etc.) and zircon beads (ZrO2 69% by mass) depending on the viscosity, specific gravity, required particle size of grinding and dispersion, and the like. %, SiO2 31 mass%), zirconia beads (ZrO2 95 mass% or more), alumina (Al2O3 90 mass% or more), titania (TiO2 77.7 mass%, Al2O3 17.4 mass%) or the like can be used. Of these, zirconia beads or zircon beads are preferably used in order to obtain good grindability. Moreover, although the particle diameter (diameter) of a grinding | pulverization media can be used in the range of 0.1 mm-3.0 mm, it is preferable that it is the range of 0.3-1.4 mm especially. When the thickness is larger than 0.1 mm, the load in the pulverizer can be reduced, and deterioration in pulverization due to melting of the toner particles due to heat generation can be suppressed. If it is smaller than 3.0 mm, sufficient pulverization can be performed. The filling rate of the dispersion medium is preferably 40 to 85% by mass. When the content is 85% by mass or less, the load in the pulverizer can be reduced, and a decrease in pulverization can be suppressed as described above. Further, when the content is 40% by mass or more, the pulverization efficiency is improved, so that miniaturization is easy. 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 a volume 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 volume average particle size (D50) is a cumulative 50 percent diameter value.
The carrier liquid (D) was used as a measurement solvent, and measurement was performed by ultrasonic treatment for 60 seconds before measurement.

  Further, the toner particles having a particle diameter of 2 μm or less with respect to all toner particles are contained in an amount of 50% by volume or less, the toner particles having a particle diameter of 1 to 3 μm are contained in an amount of 5 to 60% by volume, and the particle diameter is 5 μm or more. It is more preferable that the toner particles have 35% by volume or less from the viewpoint of development characteristics for obtaining color developability. When the toner particles having a particle size of 2 μm or less are 50% by volume or less, the polymer dispersant (C) is highly adsorbed to the toner particles, and excellent storage stability is obtained. Furthermore, the pulverization property becomes high in wet pulverization of toner particles, and the viscosity control of the liquid developer becomes easy. When the amount of toner particles having a particle diameter of 5 μm or more is less than 35% by volume, a sufficient image density can be obtained, and the effects of improving color development and color reproducibility can be obtained. Further, 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.

  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%. By setting the content to 10% by mass or more, the carrier liquid (D) can be easily removed, and high fixability of toner particles can be obtained. Further, when the content is 40% by mass or less, the viscosity of the liquid developer is lowered, the mobility of the toner particles is improved, and a sufficient image density is obtained. Furthermore, aggregation of toner particles can be suppressed, and storage stability is improved.

The viscosity (η) of the liquid developer of the embodiment is preferably 5 to 150 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. When the viscosity (η) is 5 mPa · s or more, the fineness of the image after development is improved. When the viscosity (η) is 150 mPa · s or less, the mobility of the toner particles during development is increased and high-speed development is possible. Concentration is also obtained. The electrical resistivity can be measured in the same manner as in the carrier liquid measurement method described above. When it is 10 ¹⁰ Ω · cm or more, the electrostatic latent image on the photosensitive member can be easily held.

  In the use of the liquid developer, a development process that can be preferably used is to supply the liquid developer to a developing roller made of a conductive rubber, and use an amorphous silicon photoreceptor that is charged by a scorotron charger and exposed to an LED. It is preferable to perform static elimination before transfer and development via an intermediate transfer member. The photoreceptor preferably has a surface potential of +450 to 550 V, a residual potential of +50 V or less, and the bias applied to the developing roller is preferably in the range of +250 to 450 V.

  The printing substrate to be printed with the liquid developer is not particularly limited, and examples include generally used fine paper, coated paper, PET sheet, and PP sheet. As 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。 Table 1

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)
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, and mixed with styrene monomers, acrylic acid, acrylic esters shown in Table 2, and di-t-butyl peroxide as a polymerization initiator. 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 up to 180 degreeC and toluene was removed, and the binder resin 2 containing a polyester resin and a styrene-acryl copolymer resin was obtained.

Table 2

(Binder Resin Synthesis Example 3)
In the same manner as in Synthesis Example 1, polyhydric alcohol, polybasic acid shown in Table 3 and 2 parts of dibutyltin oxide as a catalyst were added, nitrogen gas was introduced with stirring, and the reaction system was heated to 200 ° C. The reaction was continued for 7 hours while maintaining the temperature of. Furthermore, it was made to react under reduced pressure for 2 hours. 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 polyester resin 3. Furthermore, the obtained polyester resin 3 was put into 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, and mixed with styrene monomers, acrylic acid, acrylic esters, and di-t-butyl peroxide as a polymerization initiator shown in Table 4. 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 3

Table 4

  Table 5 shows the physical property values of the obtained binder resins 1 to 3.

  As binder resin 4, styrene acrylic resin Altex CPR400 manufactured by Mitsui Chemicals, Inc. was used.

Table 5

(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 (naphthenic hydrocarbon solvent, Exxon Mobil) 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 7380. 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 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 (Mw) of each polymer dispersant were as shown in Table 6.

Table 6

  As the polymer dispersant 3, Antaron-V216, which is a vinylpyrrolidone-hexadecene copolymer manufactured by ISP Japan, was used.

(Coloring agent)
Yellow colorant C.I. I. Pigment Yellow 12 (Disazo Yellow)
Parmanet Yellow DHG (manufactured by Clariant)
C. I. Pigment Yellow 13 (Disazo Yellow)
Palmet Yellow GR04 (manufactured by Clariant)
C. I. Pigment Yellow 14 (Disazo Yellow)
Irgarite Yellow D2175 (manufactured by BASF)
C. I. Pigment Yellow 74 (Monoazo Yellow)
Fast Yellow 7415 (manufactured by Sanyo Dye)
Magenta colorant C.I. I. Pigment Red 57: 1 (Kermin 6B)
Permanent Rubin L6B (manufactured by Clariant)
C. I. Pigment Red 122 (Quinacridone)
TONER MAGENTA E-02 (manufactured by Clariant)
C. I. Pigment Red 146 (Naphthol)
Permanent Carmine FBB-02 (manufactured by Clariant)
C. I. Pigment Red 147 (Naphthol)
Permanent Pink F3B01 (manufactured by Clariant)
C. I. Pigment Red 150 (Naphthol)
Toshiki Red 150T (manufactured by Tokyo Color Material Industries)
C. I. Pigment Red 269 (Naphthol)
Permanent Carmine 3810 (manufactured by Sanyo Dye)
C. I. Pigment Violet 19 (Quinacridone)
Chromo Fine Red 6835 (manufactured by Dainichi Seika Co., Ltd.)
Cyan colorant C.I. I. Pigment Blue 15: 3 (copper phthalocyanine blue)
Lionol Blue FG7919 (Toyo Color)
C. I. Pigment Blue 15: 4 (copper phthalocyanine blue)
Hostaperm Blue BT-617-D (manufactured by Clariant)
Black colorant carbon black NIPEX35 (manufactured by Orion Engineered Carbon)
C. I. Pigment Blue 15: 3 (copper phthalocyanine blue)
Lionol Blue FG7919 (Toyo Color)
C. I. Pigment Violet 23 (Dioxazine Violet)
Lionogen Violet R6200 (Toyo Color)

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

(Carrier liquid)
Exol D110 Naphthenic hydrocarbon (manufactured by ExxonMobil)
Dry point: 266 ° C. Aniline point: 83 ° C. Density: 0.808 g / cm ³ Kinematic viscosity: 3.43 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 D130 Naphthenic hydrocarbon (manufactured by ExxonMobil)
Dry point: 313 ° C. Aniline point: 88 ° C. Density: 0.827 g / cm ³ Kinematic viscosity: 6.12 mm ² / s

(Preparation of liquid developer)
Permanent Yellow DHG 12 parts by weight Binder resin 1 80 parts by weight Solsperse 24000SC 2 parts by weight The above materials (total 5 kg) were mixed (3,000 rpm, 3 minutes) with a Henschel mixer having a volume of 20 L, and then a twin-screw kneading extruder (PCM30) was melt-kneaded at a supply rate of 6 kg / hr and a discharge temperature of 145 ° C., and further kneaded with three rolls at a roll temperature of 140 ° C. After cooling and solidifying, coarsely pulverized with a hammer mill and then finely pulverized with an I-type jet mill (IDS-2 type) to obtain a pulverized toner Y1 having an average particle diameter of 7.0 μm.

Then
Toner pulverized product Y1 25 parts by weight Exol D110 73 parts by weight Polymeric dispersant 1 2 parts by weight were weighed and sufficiently stirred and mixed to disperse Yellow pulverized product 1 in the Exol D110 solution (the slurry concentration was 25 parts by weight). %). The slurry in which the yellow pulverized product 1 was dispersed was subjected to a circulation operation for 60 minutes using a wet pulverizer which is a medium stirring mill, Dino Mill Multilab (Shinmaru Enterprises Co., Ltd., capacity 1.4 L), Wet grinding was performed. The wet pulverization conditions at this time were as follows. Agitator disk (material: zirconia) peripheral speed 10 m / s, cylinder ZTA, media (material: zirconia) diameter 1.25 mm, filling rate 70%, solution flow rate 45 kg / h, cooling water 5 L / min, pressure 0.1 kg / cm ^{2 After} 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 a liquid developer Y1. When the particle size distribution was confirmed, the average particle size (D50) was 2.6 μm. The viscosity (η) was 10.0 mPa · s.

  Using the raw materials shown in Tables 7 and 8, a pulverized toner product and a liquid developer were prepared in the same manner as in the pulverized toner product Y1 and liquid developer Y1, respectively. The particle size was measured using a Nikkiso Co., Ltd. laser diffraction / scattering particle size analyzer Microtrac HRA, using Exol D80 (Exxon Mobil) as the solvent, and at 23 ° C. and 50% RH environmental conditions. Yes, the average particle size (D50) is the value of the cumulative 50 percent diameter. The viscosity (η) of the liquid developer was measured using an E-type viscometer TV-22 manufactured by Toki Sangyo Co., Ltd. After adjusting the solid content in the liquid developer to 25% and fully acclimatizing to 25 ° C, set the 1 ° 34 'cone in the TV-22 type viscosity shape, and measure the viscosity after 1 minute at 20 rpm. Asked.

Table 7

Table 8

  Table 9 shows the physical property values of the obtained liquid developer.

Table 9

(Live-action test)
In the live-action test, a commercially available liquid developing copier (Savin 870: manufactured by Sabin) was used, an amorphous silicon photoconductor was used under an environmental condition of 23 ° C./50% RH, and the surface potential of the photoconductor was +450. An image test of 100 sheets was performed from the initial stage with ˜500 V, residual potential +50 V or less, and developing roller bias set to +250 to 450 V. The 100th image was used for image evaluation. At this time, single color image preparation is solid with yellow, magenta, cyan, and black single colors, and red (yellow x magenta), blue violet (magenta x cyan), and green (cyan x yellow) two-color superimposed image preparation is single color. After the solid printing, a solid color was printed. 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 120 ° C.

(Single color output image evaluation)
For single-color image evaluation, yellow, magenta, cyan, and black single-color image outputs were performed at a toner particle concentration of 25%. The density of the solid portion of the obtained monochromatic image sample was measured with X-Rite 504. Generally, the image density of each process color (in the case of filter Status-T) is a density value of 0.9 or more for yellow, 1.4 or more for magenta, 1.5 for cyan, and 1.7 or more for black. Practically preferred. The standard for evaluating the monochrome density for each color is shown below. A density value of ◯ or higher is preferred for practical use, and more preferably a density of ◎ or higher.
Yellow ◎: 1.0 or more ○: 0.9 or more and less than 1.0 ×: Less than 0.9 Magenta ◎: 1.5 or more ○: 1.4 or more and less than 1.5 ×: Less than 1.4 cyan ◎: 1 .6 or more ○: 1.5 or more and less than 1.6 ×: less than 1.5 Black ◎: 1.8 or more ○: 1.7 or more and less than 1.8 ×: less than 1.7

(Overlapping output image evaluation)
All color reproduction areas that can be represented by printed matter are called color rendering areas (gamuts). The simplest way to represent gamuts is to create a single-color solid part (a * on the horizontal axis and b * vertical axis in a two-dimensional space. The values of a * vs. b * for a total of six colors, yellow, magenta, and cyan) and the overlapped solid portion (red, blue violet, and green), can be expressed as a plotted hexagonal area. The larger the gamut area, the wider the color reproduction area.

(Overlay transfer efficiency measurement)
At the time of output of the superimposed image, the liquid developer layer of the photosensitive member before and after the liquid developer was transferred from the photosensitive member to the intermediate transfer member was collected with a tape, adhered on paper, and density measurement was performed with X-Rite 504. The transfer efficiency of superposition is
Transfer efficiency = (density before passage) / ((density before passage) + (density after passage)) × 100
It calculated | required by the calculation formula of. The transfer efficiency is desirably 90% or more if practical, and more preferably 95% or more.
◎: Transfer efficiency is 95% or more ○: Transfer efficiency is 90% or more and less than 95% ×: Transfer efficiency is less than 90%

  Table 11 shows the results of measuring the transfer efficiency of the overlapping. Overlapping image output is performed in the order of cyan, magenta, yellow, Y / M transfer efficiency is yellow on magenta, Y / C transfer efficiency is yellow on cyan, and M / C transfer efficiency is transfer efficiency on yellow on cyan. Indicates.

(Colorimetry)
Generally, the image density of each process color is practically preferable if the density value is 0.9 or more for yellow, 1.4 or more for magenta, and 1.5 or more for cyan. Therefore, in order to compare the color rendering regions (gamut), the solid image density of a process single color is 0.9 to 1.0 for yellow, 1.4 to 1.5 for magenta, and 1.5 to 1.6 for cyan. The toner sample concentration was adjusted and the bias of the developing roller was adjusted so as to be within the range, and an image sample was output. The output image samples are X-Rite 504 (filter Status-T), L *, a *, b of single colors (yellow, magenta, cyan) and superimposed secondary colors (red, blue violet, green). * Measured value.

  The results are shown in Table 10, and the gamut is shown in FIGS. Further, FIGS. 4 to 7 show enlarged views of the gamut red region, magenta region, blue violet region, and green region.

Table 10

  In the monochromatic output image evaluation, all of the yellow, magenta, and cyan liquid developers and the black liquid developers K1 to K4, K6, and K7 have good image densities. In the liquid developer K5, since the colorant (B) is only carbon black, a sufficient monochrome image density cannot be obtained. In the superimposed image output evaluation, Examples 1 to 7 have good overlay transfer efficiency and a wide color reproduction region. In particular, Examples 2 to 6 have excellent overlap transfer efficiency and color reproduction area. In Comparative Example 1, in the colorant (B), the yellow colorant does not contain Pigmented Yellow 12, 13, and 14, and the magenta colorant is only Pigment Red 57: 1. However, the color reproduction range of red, magenta, and blue violet is narrowed. In Comparative Example 2, since the binder resin (A) does not contain polyester, the transfer efficiency of the overlap is lowered, and the color reproduction regions of red, blue violet, and green are narrowed. In Comparative Example 3, the polymer dispersant is 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 a polymer dispersant having an amine value of 5 to 150 mgKOH / g is not included, and therefore, the transfer efficiency of superposition is lowered, and red, blue violet, and green color reproduction regions are produced. Narrow.

  The liquid developer of the present invention is excellent in superimposing transfer rate and color reproducibility, and is used in an electrophotographic copying machine, a printer, an on-demand printing machine, etc., in which an image is formed using an electrophotographic method, an electrostatic recording method, or the like. It can be preferably used as a liquid developer set used for developing an electrostatic latent image.

Claims (5)

A liquid developer set consisting of at least four colors of yellow, magenta, cyan and black,
Each of the yellow, magenta, cyan, and black liquid developers includes a binder resin (A), a colorant (B), a polymer dispersant (C), and a carrier liquid (D).
The binder resin (A) independently includes a polyester resin (a-1),
The colorant (B)
Yellow liquid developer is C.I. I. Including any of CI Pigment Yellow 12, 13, and 14;
The magenta liquid developer is C.I. I. Pigment Red 57: 1, and C.I. I. Pigment red 122, 146, 147, 150, 269, and C.I. I. Including any one of Pigment Violet 19,
The cyan liquid developer is C.I. I. Including any of CI Pigment Blue 15: 3 and 15: 4,
The black liquid developer contains carbon black, and C.I. I. Any one of CI Pigment Blue 15: 3, 15: 4, and Pigment Violet 23,
The polymer dispersant (C) is independently an ethylenically unsaturated monomer having an amino group (c-1) and an ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms ( c-2) and a polymer dispersant having an amine value of 5 to 150 mgKOH / g.
The liquid developer set, wherein each of the carrier liquids (D) is independently an aliphatic hydrocarbon.   The liquid developer set according to claim 1, wherein the binder resin (A) further contains at least one selected from a styrene resin, an acrylic resin, and a styrene-acrylic copolymer resin.   The liquid developer set according to claim 1, wherein the binder resin (A) has a softening temperature of 80 to 140 ° C. and a weight average molecular weight (Mw) of 2000 ≦ Mw ≦ 100,000.   The liquid developer set according to any one of claims 1 to 3, wherein the carrier liquid (D) is an aliphatic hydrocarbon having a dry point in a distillation range of 200 ° C to 280 ° C. Printed matter obtained using the liquid developer set according to claim 1.

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