JP6248745B2 - Liquid developer set and printed matter using the same - Google Patents

Description

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

In the output by offset printing, a printing method using 5 to 7 color ink sets as a high saturation printing system has been established, and as a printing method using ink sets having respective specified hues, orange and green are used for four process colors. There are established 6 colors (hexachrome printing), and 7 colors (high fidelity printing) with orange, green, and purple added to 4 process colors. (See Patent Document 1)
In addition, studies have been made to obtain a wide range of image reproduction even with dry powder toners. (See Patent Documents 2, 3, 4, and 5)

 For an image forming apparatus using a liquid developer, a developer in which finely divided toner particles are dispersed in a carrier liquid is used, and an electrostatic latent image formed by exposure on a photoconductor is a carrier liquid. The electrostatic latent image developed using the toner particles therein is printed on a recording medium such as paper, for example, a basic process of Y (yellow), M (magenta), C (cyan) and Bk (black). By transferring, drying and fixing the four color liquid developers, an image having excellent color reproducibility can be formed. In addition, an image having further excellent color reproducibility can be formed by using an intermediate color such as violet or green.

  Since the image forming apparatus using the liquid developer performs fine pulverization and dispersion under wet conditions, it can be miniaturized, and since the carrier liquid of the insulating liquid is used as a carrier, there is a problem due to scattering of toner particles in the machine. As compared with the dry powder toner, 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. (For example, refer to Patent Documents 6 and 7).

 Full-color images in the four process colors have the specified hues of single colors Y, M, and C. In addition, the color reproduction area is red by yellow and magenta, blue violet by magenta and cyan, and green by cyan and yellow. And an image with 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 expand the color reproduction region by increasing the colorant concentration in the toner particles, but the toner particles not only in the image area but also in the non-image area where the fixability to the recording medium deteriorates. The “fogging phenomenon” is transferred, and there is room for improvement in order to satisfy all of these.

JP 2001-260516 A JP-A-9-171268 JP 2001-312102 A JP-A-5-72810 Japanese Patent Application No. 5109404 JP-A-5-333607 Special table 2007-505953 gazette

  As described above, the image forming apparatus using the liquid developer has room for improvement in obtaining both excellent color reproducibility and transferability, fogging and fixing properties. There is a need for a liquid developer set that solves this problem and has excellent color reproducibility.

  SUMMARY An advantage of some aspects of the invention is that it provides a liquid developer set having excellent 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, the present invention provides a liquid developer having a plurality of liquid developers comprising at least a binder resin (A), a colorant (B), a polymer dispersant (C), and a carrier liquid (D). A set,
At least the colorant (B) is C.I. I. Pigment Yellow 185, a yellow liquid developer, and the colorant (B) are C.I. I. It relates to a liquid developer set which comprises a magenta liquid developer containing Pigment Red 150.

In the present invention, the mass ratio [binder resin (A) / colorant (B)] of the binder resin (A) to the colorant (B) in all of the plurality of liquid developers is 2.6 to 12. The liquid developer set according to claim 1, wherein:

The present invention also relates to the above liquid developer set, wherein the binder resin (A) in all of the plurality of liquid developers includes at least a polyester resin.

In the present invention, the binder resin (A) of the magenta liquid developer contains a polyester resin and a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin. The present invention relates to a developer set.

In the present invention, the entire binder resin (A) in all of the plurality of liquid developers has a softening temperature of 80 to 140 ° C., and a weight average molecular weight Mw of 2000 ≦ Mw ≦ 100,000. It relates to a liquid developer set according to any claims 1-4 to.

In the present invention, the polymer dispersant (C) in all of the plurality of liquid developers includes at least an ethylenically unsaturated monomer having an amino group and an ethylene having an alkyl group having 9 to 24 carbon atoms. The liquid developer set according to the above, wherein the amine value is 5 to 150 mgKOH / g.

The present invention is also characterized in that the polymer dispersant (C) in all of the plurality of liquid developers is obtained by copolymerizing at least an ethylenically unsaturated monomer represented by the following general formula (1). The present invention relates to the liquid developer set.
General formula (1)
CH ₂ = C (R ¹ ) COO (AO) nR ²
Wherein R ¹ is H or CH ₃ , R ² is hydrogen or a hydrocarbon group having 1 to 22 carbon atoms, and n is 1
An integer of ˜200, A represents an alkylene group having 2 to 4 carbon atoms. )

In the present invention, the weight average molecular weight Mw of the polymer dispersant (C) in all of the plurality of liquid developers is 500 ≦ Mw ≦ 400.
The liquid developer set is characterized by being 00.

The present invention also relates to the above liquid developer set, wherein the carrier liquid (D) in all of the plurality of liquid developers is an aliphatic hydrocarbon.

  The present invention also relates to a printed matter obtained by printing using the above liquid developer set.

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

Gamut (yellow) Gamut (green) Gamut (red) Gamut (red) Gamut (Magenta) Gamut (Magenta) Gamut (blue violet) Gamut (blue violet)

Hereinafter, the present invention will be described in detail.
The liquid developer set according to the embodiment of the present invention includes a plurality of liquid developments including at least a binder resin (A), a colorant (B), a dispersant (C), and a carrier liquid (D). An agent set, wherein at least the colorant (B) is C.I. I. Pigment Yellow 185, a yellow liquid developer, and C.I. I. Pigment red 146, 147, 150, 269, and C.I. I. And a magenta liquid developer selected from the group consisting of CI Pigment Violet 19.

 C. I. Pigment Yellow 185 exhibits a bright yellow color and is excellent in color developability and transparency. Therefore, in the L * a * b * color system (CIE 1976), the b * value is large. I. Since CI Pigment Yellow 185 has high insulation properties, it has good transferability of overlapping, so that at least the colorant (B) is C.I. I. By using a yellow liquid developer having a pigment number of 185, an image having excellent color reproducibility in the red and green regions can be obtained.

C. I. Pigment red 146, 147, 150, 269, C.I. I. Pigment Violet 19 has good dispersibility with respect to the binder resin (A), so it has excellent color development and transparency, has a large a * value, and is difficult to elute into the carrier liquid (D). To at least the colorant (B) is C.I. I. Pigment red 146, 147, 150, 269, and C.I. I. By using a magenta liquid developer selected from the group consisting of Pigment Violet 19, an image having excellent color reproducibility in the red and blue violet regions can be obtained.

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

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

  Examples of yellow colorants include C.I. which is an isoindoline compound. I. It is preferable to use an organic pigment of CI Pigment Yellow 185. Although the said organic pigment may be used independently, 2 or more types can also be mixed and used as long as the quality at the time of using independently 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 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 138, 139, 147, 150, 168, 174, 176, 180, 181, 191 and the like are preferably used.

  Examples of the magenta colorant include C.I. I. Pigment red 146, 147, 150, 269, and C.I. I. It is preferable to use an organic pigment selected from the group consisting of CI Pigment Violet 19. These can be used alone or in admixture of two or more. Moreover, as long as quality is not impaired, it can be used even if it mixes organic pigments other than the above. As magenta colorants that may be mixed, basic dye lake compounds such as condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, 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, 57: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 122, 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.

As the cyan colorant, it is preferable to use cyan or blue organic pigments. As the cyan organic pigment, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 60, 62, 66 and the like are preferably used. Among them, C.I. I. It is preferable to use a copper phthalocyanine compound such as CI Pigment Blue 15: 3.
It is also preferable to use a compound derived from a triarylmethane dye in a form used in combination with the organic pigment. Triarylmethane dyes are effective materials in terms of both charge control and colorability because they have good positive chargeability. In particular, C.I. I. A triarylmethane oil-soluble dye such as Solvent Blue 124 or a salt-forming compound of a triarylmethane basic dye is good. C. I. As the solvent blue 124, specifically, COPY BLUE PR manufactured by Clariant is a preferable material. This is C.I. I. It was obtained by condensing Basic Red 9 (paramagenta) and aniline.
Further, for the purpose of adjusting the hue, in addition to the cyan or blue organic pigment, the salt forming compound of cyan or blue dye, the oil-soluble dye of cyan or blue dye, a green pigment can be used as a complementary color. Specific examples of the green pigment include C.I. I. Halogenated phthalocyanine compounds such as CI Pigment Green 7 and 36 are preferred.

From the viewpoint of cost and handling, it is preferable to use organic black pigments such as carbon black and perylene black, and organic black dyes such as nigrosine dyes and azo metal complex dyes as the black colorant.
As carbon black, any of various types such as furnace black, channel black, acetylene black, carbon black derived from biomass can be used. Furnace black carbon and biomass carbon are preferable because they have an effect of reducing fog (background stain on the white background) in image characteristics.
As the nigrosine dye, it is preferable to use a nigrosine base that is refined by wet pulverization or the like and has a volume average particle size of 0.5 to 2 μm. Since the refined nigrosine dye has a gloss, a glossy black color can be obtained. Nigrosine refinement can be obtained by the method described in JP-A-2006-171501.
Further, as the black colorant, black can be obtained using the above three colorants of yellow, magenta, and cyan.

Furthermore, in order to obtain black with good image density and contrast, it is preferable to use a colorant in which 1 to 10 parts by mass of a blue colorant is added to 100 parts by mass of the black colorant as a black colorant. . As the blue colorant, it is preferable to use a halogen-free metal phthalocyanine blue compound, a triarylmethane compound, a dioxazine violet pigment, or the like. In addition, the phthalocyanine blue compound and the triarylmethane compound have a stable positive charging property, which is effective in obtaining good black toner particles. Specifically, C.I. I. Pigment Blue 15: 3, Victoria Pure Blue Lake Pigment (CI Pigment Blue 1), C.I. I. Pigment violet 23, C.I. I. Pigment Violet 19, a salt-forming compound composed of a triarylmethane-based basic dye and a substantially colorless organic acid (a salt-forming compound of CI Basic Blue 7 and an organic acid), a triarylmethane-based oil-soluble dye Etc. are preferably used.
Triarylmethane dyes are effective in controlling the chargeability of toner particles by exhibiting good positive charge, and among them, triarylmethane oil-soluble dyes having excellent dispersibility are preferred.

  The content of the colorant (B) contained in the toner particles varies depending on the type of the binder resin (A) used, but usually the mass ratio of the binder resin (A) to the colorant (B) [binder. Resin (A) / Colorant (B)] is 2.6-12, preferably 3-8. When the mass ratio is 2.6 or less, since the ratio of the binder resin (A) to the colorant (B) is small, the film forming property of the toner particles at the time of melting deteriorates and the fixing property deteriorates. In some cases, as compared with the binder resin (A), since the insulating property is low, the chargeability as the toner particles is inferior, which may cause fogging and decrease in the transfer rate. Further, when the mass ratio is 12 or more, the ratio of the colorant (B) is small, and problems such as insufficient image density and color developability may occur.

(Binder resin (A))
In general, the binder resin has a function of uniformly dispersing a colorant such as a pigment or a dye in the resin and a function as a binder when fixing to a substrate such as paper.
Examples of binder resins that can be used include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer Styrene-vinyl naphthalene copolymer, styrene- (meth) acrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, Styrene copolymers such as styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, and crosslinked. Styrene copolymer; Polyvinyl chloride , Phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral resin Terpene resin, coumarone indene resin, petroleum resin and the like.
As the binder resin (A) used in the liquid developer of the present invention, a polyester resin (a-1) is particularly preferable from the viewpoint of pigment dispersibility, grindability, and fixability. More preferably, it contains a polyester resin and a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin (a-2). More preferably, it includes a polyester resin and a styrene-acrylic copolymer resin. Furthermore, in order not to disturb the hue of the color material of each color, those exhibiting colorless, transparent, white or light color are preferable.

  The polyester resin is preferably a thermoplastic polyester, specifically, for example, obtained by polycondensation of a divalent or trivalent or higher alcohol component and an acid component such as carboxylic acid.

Examples of the alcohol component include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,4-butenediol, Diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, bisphenol A, hydrogenated bisphenol A, 1,4-bis (hydroxy Methyl) cyclohexane, divalent alcohols such as bisphenol derivatives represented by the following general formula (2),
Examples of trihydric or higher alcohols such as glycerol, diglycerol, sorbit, sorbitan, butanetriol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc. are used alone or in combination Used in combination.

（式中Ｒはエチレンまたはプロピレン基であり、ｘ、ｙはそれぞれ１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。） General formula (2)

(In the formula, R is an ethylene or 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 its anhydride;
And a succinic acid or anhydride thereof further substituted with an alkyl group having 16 to 18 carbon atoms;
Unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid or anhydrides thereof;
Examples thereof include cyclohexanedicarboxylic acid; naphthalenedicarboxylic acid; diphenoxyethane-2,6-dicarboxylic acid, and the like as trivalent or higher carboxylic acids acting as a crosslinking component are trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, butanetricarboxylic acid. Hexanetricarboxylic acid, tetra (methylenecarboxyl) methane, octanetetracarboxylic acid, benzophenonetetracarboxylic acid and anhydrides thereof, and the like are used alone or in combination of two or more.

  Preferred alcohol components are those obtained by adding 2 to 3 moles of alkylene oxide to bisphenol A, ethylene glycol, neopentyl glycol, etc., and preferred acid components are phthalic acid, terephthalic acid, isophthalic acid or its anhydride, succinic acid, n-dodecenyl succinic acid or its anhydride, dicarboxylic acids such as fumaric acid, maleic acid and maleic anhydride, and tricarboxylic acids such as trimellitic acid or its anhydride.

  Moreover, as a catalyst used for the polycondensation of the polyester resin (a-1), a known and usual reaction catalyst such as at least one metal compound selected from antimony, titanium, tin, zinc and manganese is used, and the reaction is promoted. Also good. 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 and softening temperature of the polyester resin, the kind and molar ratio of the alcohol component and carboxylic acid to be reacted, as well as the reaction temperature and reaction time. The 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.).

  Further, in order to improve fixability and grindability, the binder resin (A) is a polyester resin (a-1) and a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin (a-2). Is preferably included. The styrene resin is the following styrene monoer, the acrylic resin is (meth) acrylic acid or the following (meth) acrylic ester, the styrene-acrylic copolymer resin (a-2) is the following styrene monomer, It is obtained by polymerizing at least one of acrylic acid and the following (meth) acrylic acid esters.

  Styrene monomers include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, p-ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert. -Butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, Examples include p-chlorostyrene and 3,4-dichlorostyrene.

  (Meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) acrylic acid Octyl, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-chloroethyl (meth) acrylate, phenyl (meth) acrylate, acrylic acid Examples include dimethylaminoethyl and diethylaminoethyl (meth) acrylate.

  A preferred styrenic monomer is styrene, and preferred (meth) acrylic acid esters are butyl (meth) acrylate, octyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

  In order to increase the molecular weight of the styrene resin, acrylic resin, or styrene-acrylic copolymer resin (a-2), 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 (meth) ) Acrylate.

  The styrene-acrylic copolymer resin composed of the styrene resin, acrylic resin, or styrene monomer and (meth) acrylic acid and (meth) acrylic acid ester is a suspension polymerization method, solution polymerization method, emulsion weight It can be obtained by a known polymerization method such as a combination method. To control the molecular weight and softening temperature of the styrene-acrylic copolymer resin, the types and molar ratios of the styrene monomer and (meth) acrylic acid and (meth) acrylic acid esters, as well as the reaction temperature, reaction time, and reaction What is necessary is just to adjust a pressure, a polymerization initiator, a crosslinking agent, etc. Further, a commercially available product can be used as the styrene-acrylic copolymer resin (a-2). 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 styrene-acrylic copolymer resin (a-2), the polyester resin (a-1 ) And a styrene-acrylic copolymer resin (a-2) or the like, and in the presence of either a polymerized polyester resin (a-1) or a styrene-acrylic copolymer resin (a-2), There is a method in which the other monomer is added for polymerization. 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 a styrene-acrylic copolymer resin (a-2) or the like 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, such as patent 3531980 and Unexamined-Japanese-Patent No. 2006-178296.

  In addition, when a polyester resin (a-1) and a styrene resin, or an acrylic resin, or a styrene-acrylic copolymer resin (a-2) are separately produced, a commercially available polyester resin, a styrene-acrylic copolymer resin When using, the binder resin (A) can be obtained by mixing the polyester resin (a-1) and the styrene-acrylic copolymer resin (a-2). At this time, either of them may be dissolved in a solvent, mixed and desolvent, or melt-kneaded.

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

(Softening temperature (T4))
The softening temperature of the binder resin (A) used in the present invention is preferably in the range of 80 to 140 ° C. More preferably, it is the range of 90 to 130 degreeC. The softening temperature in the present invention is as follows. Using a flow tester CFT-500D manufactured by Shimadzu Corporation, a starting temperature of 40 ° C., a heating rate of 6.0 ° C./min, a test load of 20 kg, a preheating time of 300 seconds, and a die hole diameter of 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 lower than 80 ° C., the binder resin (A) is excessively softened during kneading, the dispersion of the colorant (B) is deteriorated, and a sufficient image density as a liquid developer may not be obtained. is there. Furthermore, in the fixing process at the time of image output, the surface of the thermocompression roller and the toner image are in contact with each other in a molten state, so that the cohesive force of the toner particles is smaller than the adhesive force between the substrate and the thermocompression roller. The portion is not completely fixed, and the toner particles adhere to the surface of the thermocompression roller, and a hot offset phenomenon is likely to occur and transfer to the next paper. On the other hand, when the softening temperature is higher than 140 ° C., there are cases in which good fixability cannot be obtained, grindability is deteriorated, and dispersion stability and color developability are deteriorated.

(Weight average molecular weight (Mw))
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) in terms of offset resistance, fixing property and image quality characteristics. 000 is preferable, and 5,000 to 50,000 is more preferable. When the weight average molecular weight (Mw) of the binder resin (A) is smaller than 2,000, hot offset resistance, color reproducibility and dispersion stability are lowered, and when it is larger than 100,000, the fixing property is deteriorated. Problems may occur.
In addition, the binder resin (A) used in the present invention is a type having a molecular weight distribution curve of two peaks composed of a specific low molecular weight condensation polymer component and a specific high molecular weight condensation polymer component, or one peak. Any of the types having a single molecular weight distribution curve may be used.

  Furthermore, the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the binder resin (A), Mw / Mn, is preferably in the range of 2-15. When Mw / Mn is less than 2, the offset resistance is deteriorated, the non-offset region is narrowed, and the low temperature fixability is sometimes deteriorated. When Mw / Mn exceeds 15, the pulverizability of the toner particles may be deteriorated, and the image characteristics may be deteriorated such that a sufficient image density cannot be obtained or the color developability is deteriorated.

In addition, the molecular weight distribution by said GPC was 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.

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

  A measurement sample was 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. Then, the sample that has passed through the sample processing filter is used as a GPC measurement sample. The sample concentration was adjusted so that the resin component was 0.5 to 5 mg / ml.

(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) includes an ethylenically unsaturated monomer having a tertiary amino group, an ethylenically unsaturated monomer containing an alkyl group having 9 to 24 carbon atoms, and a compound represented by the general formula (1): It can be obtained from a copolymerizable monomer containing an ethylenically unsaturated monomer. The polymerization method of the polymer dispersant (C) suitable for the present invention is solution polymerization of a normal acrylic resin.

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

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

As the ethylenically unsaturated monomer having a tertiary amino group in the polymer dispersant (C), for example,
N, N such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, etc. -Dialkylamino group-containing (meth) acrylic acid esters; and
N, N such as N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide -Dialkylamino group-containing (meth) acrylamides; and
Examples thereof include dimethylaminostyrene and diethylaminostyrene.

  It can also be obtained by a weight monomer that can be polymerized with an ethylenically unsaturated monomer having a secondary amino group. 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, and N, N-dimethylaminopropyl (meth) acrylamide are preferable from the viewpoint of dispersibility.

  The amine value of the polymer dispersant (C) is preferably 5 to 150 mgKOH / g. More preferably, it is 30-100 mgKOH / g. When the amine value is lower than 5 mgKOH / g, the adsorption to the toner particles is weak and the pulverizability in wet pulverization may be lowered. Furthermore, during storage for a long period of time, the toner particles aggregate, the viscosity of the liquid developer and the average particle size of the toner particles may increase, and the storage stability may decrease. When the amine value is higher than 150 mgKOH / g, the chargeability of the toner particles becomes low, the toner particles are hardly transferred to the substrate, and a good image density may not be obtained. Furthermore, the solubility in the carrier liquid (D) is lowered, and the grindability may be lowered. The amine value of the polymer dispersant (C) is the total amine value (mgKOH / g) measured according to the method of ASTM D2074.

  Further, among the polymer dispersant (C), the ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms has a solubility in the carrier liquid (D) of the alkyl group having 9 to 24 carbon atoms. It improves the pulverization property of the toner particles in wet pulverization, and further suppresses the aggregation of toner particles and the increase in viscosity of the liquid developer during storage for a long period of time, and exhibits an excellent storage stability effect. . When the alkyl group has less than 9 carbon atoms, the solubility in the carrier liquid (D) is low, and the dispersion stability and storage stability of the toner particles are low. When the carbon number of the alkyl group is larger than 24, when the liquid developer is fixed to the substrate, the long alkyl group may interfere with contact and coalescence of the toner particles, and the fixability may be lowered. Furthermore, the chargeability of the toner particles may be lowered, causing the toner particles to be difficult to be transferred to the substrate and causing problems such as insufficient image density.

  Of the polymer dispersant (C), the ethylenically unsaturated monomer of the general formula (1) is effective for improving the fixing property. If the ethylenically unsaturated monomer of the general formula (1) is not included, the compatibility with the binder resin (A) is lowered, and in the fixing process, the molten state of the toner particles becomes incomplete and the substrate becomes a substrate. The fixability of the ink may deteriorate. In addition, there may be a case where a cold offset phenomenon in which insufficiently melted toner particles adhere to the thermocompression roller and transfer to the next paper is likely to occur.

Examples of the ethylenically unsaturated monomer having an alkyl group having 9 to 24 carbon atoms include:
Nonyl (meth) acrylate, 8-methylnonyl (meth) acrylate, 2-methylnonyl (meth) acrylate, decyl (meth) acrylate, 2-methyldecyl (meth) acrylate, undecyl (meth) acrylate, 2-methylundecyl (meth) Acrylate, 9-methylundecyl (meth) acrylate, dodecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, 11-methyldodecyl (meth) acrylate, tridecyl (meth) acrylate, 2-methyltridecyl (meth) Acrylate, tetradecyl (meth) acrylate, 2-methyltetradecyl (meth) acrylate, pentadecyl (meth) acrylate, 2-methylpentadecyl (meth) acrylate, hexadecyl (meth) acrylate, 2- Tylhexadecyl (meth) acrylate, heptadecyl (meth) acrylate, 2-methylheptadecyl (meth) acrylate, octadecyl (meth) acrylate, 2-methyloctadecyl (meth) acrylate, nonadecyl (meth) acrylate, 2-methylnonadecyl (meth) acrylate , (Meth) acrylates such as alkyl (meth) acrylate having an alkyl group having 9 to 24 carbon atoms, such as 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- Tilundecyl) (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 (Meth) acrylamide, N-heptadecyl (meth) acrylamide, N- (1-methylheptadecyl (meth) acrylamide), N-octadecyl (meth) acrylamide, N, N-dioctadecyl (meth) acrylamide, N-nonade Alkyl (meth) acrylamides having an alkyl group having 9 to 24 carbon atoms such as ru (meth) acrylamide, N-icosyl (meth) acrylamide, N-henicosyl (meth) acrylamide, N-docodesyl (meth) acrylamide; and 4 -Nonylphenyl (meth) acrylate, 4'-decyl-4-biphenylyl (meth) acrylate, 3-pentadecylphenyl (meth) acrylate, N- (10-phenyldecyl) (meth) acrylamide, N- (4-dodecyl) Phenyl) (meth) acrylamide, N- [2- (1-naphthyl) ethyl] -N-dodecyl (meth) acrylamide, N- [4- (1-pyrenyl) butyl] -N-dodecyl (meth) acrylamide, N -Octadecyl-N- [2- (1-naphthyl) ethyl] (meth) act (Meth) acrylates and (meth) acrylamides having an aromatic ring such as ruamide and an alkyl group having 9 to 24 carbon atoms; and 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-hexadecene, 4-hexadecene, 1-heptadecene, 2-heptadecene, 4-heptadecene, 1-octadecene, Examples thereof include α-olefins having an alkyl group having 9 to 24 carbon atoms, such as 2-octadecene, 4-octadecene, 1-docosene, 2-docosene, and 4-docosene.

  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.

  The ethylenically unsaturated monomer represented by the general formula (1) is, for example, a ring-opening polymerization of ethylene oxide with an alkyl alcohol and then a transesterification reaction with methyl (meth) acrylate or a reaction with (meth) acrylic acid chloride. Can be obtained.

General formula (1)
_{CH 2 = C (R1) COO} (AO) nR2
(Wherein, R1 is H or CH _3, R2 is a hydrocarbon group of hydrogen or carbon atoms 1 to 22, n is an integer of 1 to 200, A represents an alkylene group having 2 to 4 carbon atoms.)

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

The number (n) of alkylene oxide groups is an integer of 1 to 200, preferably an integer of 1 to 30. When exceeding 200, sufficient compatibility with the ethylenically unsaturated monomer which has a C9-C24 alkyl group in the molecule | numerator mentioned above may not be acquired.
R2 is hydrogen or a hydrocarbon group having 1 to 22 carbon atoms. A carbon number of 23 or more is not practical because the raw material is expensive. 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 (1) may be used in combination.

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

Other unsaturated compounds that may be included include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and 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) acrylate, etc. (Meth) acrylates such as alkyl (meth) acrylates having 1 to 8 alkyl groups; and N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N -Butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-isopentyl (meth) acrylamide, N-neopentyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-isohexyl (meth) acrylamide, N (Meth) acrylamides such as -n-heptyl (meth) acrylamide, N- (6-methylheptyl) (meth) acrylamide, N-octyl (meth) acrylamide, N- (7-methyloctyl) (meth) acrylamide; And 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 -1-8 carbon atoms such as nonene, 2-nonene, 1-decene, 2-decene And α-olefins having the following alkyl groups.

further,
Cyclohexyl (meth) acrylate, Tertiarybutylcyclohexyl (meth) acrylate, Dicyclopentanyl (meth) acrylate, Dicyclopentanyloxyethyl (meth) acrylate, Dicyclopentenyl (meth) acrylate, Dicyclopentenyloxyethyl (meth) ) Acrylates or cyclic alkyl (meth) acrylates such as isobornyl (meth) acrylate;
(Meth) acrylates having an aromatic ring such as benzyl (meth) acrylate;
Examples thereof include vinyls such as styrene, α-methylstyrene, vinyl acetate, vinyl (meth) acrylate, and allyl (meth) acrylate.
Unsaturated compounds other than those described above can also be used as long as they do not affect the physical properties.

  The weight average molecular weight (Mw) of the polymer dispersant (C) is not limited to a specific range, but is 500 to 40,000 in consideration of dispersibility and grindability when the toner particles are wet-dispersed. It is preferable.

(Other dispersants)
As the dispersant, in addition to the polymer dispersant (C) used in the present invention, a dispersant conventionally used in a liquid developer may be used. Specifically, fatty acid metal salts such as cobalt naphthenate, zinc naphthenate, copper naphthenate, manganese naphthenate, cobalt octylate and zirconium octylate, titanate coupling agents of organic titanates such as lecithin and titanium chelate, alkoxy Examples include titanium polymers, polyhydroxy titanium carboxylate compounds, titanium alkoxides, succinimide compounds, polyimine compounds, fluorine-containing silane compounds, and pyrrolidone compounds. In particular, titanium alkoxide, a succinimide compound, a fluorine-containing silane compound, a pyrrolidone-based compound, and the like may be mixed and used in an appropriate amount within a range of 5 parts by mass or less with respect to 100 parts by mass of the liquid developer.
In this case, the dispersant is used in such a manner that the dispersant having the same polarity as the toner particles is adsorbed on the toner particles, and the dispersant having the opposite polarity to the toner particles is not adsorbed on the toner particles and dispersed in the carrier liquid. It becomes a form to make it. At this time, the standard for discussing the polarity is the polarity with respect to the carrier liquid. In addition, this behavior is determined after an actual image test and is obtained empirically.

(Carrier liquid (D))
The carrier liquid (D) used for the liquid developer is preferably an aliphatic hydrocarbon. Examples of the aliphatic hydrocarbon include linear paraffin hydrocarbons, isoparaffin hydrocarbons, and naphthene hydrocarbons. Among these, paraffinic hydrocarbons with very little residual aromatic hydrocarbon are preferable. Further, those having lipophilic properties, chemically stable and insulating properties are preferred. Further, the carrier liquid needs to be chemically inert to a substance or device used in the image forming apparatus, in particular, a member for a development process such as a photosensitive member and members around the member.

The dry point in the distillation range of the carrier liquid (D) is preferably in the range of 180 to 360 ° C. Especially preferably, it is the range of 200-340 degreeC. When the temperature is lower than 180 ° C., the liquid developer is dried at room temperature, solid matter is deposited, and the regulation blade around the development is fixed, which may cause image contamination. On the other hand, when the temperature is higher than 360 ° C., it may be difficult to remove the carrier liquid (D) and the fixability may be lowered.
Here, the dry point in the distillation range is determined by the method defined by ASTM D86, ASTM D1078, and JIS K2254.

Moreover, as a carrier liquid (D), it is preferable to use what has a Kauri butanol numerical value (KB value: ASTM D1133) 30 or less. More preferably, it is the range of 20-30. The aniline point (JIS K2256) is preferably in the range of 60 to 105 ° C., more preferably 70 to 95 ° C., in order to obtain a stable carrier liquid.
When the Kauributanol value exceeds 30 or the aniline point is lower than 60 ° C., the solubility as a solvent is high and the carrier liquid dissolves the toner particles, so the storage stability and color reproducibility of the toner particles are low. In some cases, the carrier liquid may be colored to contaminate a substrate such as paper. When the aniline point exceeds 105 ° C., the compatibility with the dispersant and additives added when dispersing the toner particles in the carrier liquid is low, causing problems such as poor dispersion and insufficient image density. There is a case.

Specifically describing the insulating properties of the carrier liquid (D), the dielectric constant is 5 or less, preferably 1 to 5, and more preferably 1 to 3.
At the same time, the electric resistivity of the carrier liquid (D) is preferably 10 9 Ω · cm or more, more preferably 10 10 Ω · cm or more, and particularly preferably 10 10 to 10 16 Ω · cm. Here, the electrical resistivity can be determined by combining a universal electrometer MMA-II-17D manufactured by Kawaguchi Electric Manufacturing Co., Ltd. and a liquid electrode LP-05. When the electrical resistivity is less than 10 9 Ω · cm, the chargeability of the toner particles becomes low, a sufficient image density cannot be obtained, and color reproducibility and color developability may be lowered.

Further, the density (JIS K2249) at 15 ° C. of the carrier liquid (D) is preferably in the range of 0.67 to 0.9 g / cm 3. More preferably, it is 0.70 to 0.85 g / cm3. This range is preferable because toner particles and a dispersant can exist stably, and thus excellent fixing properties and image density can be obtained.
The carrier liquid (D) preferably has a kinematic viscosity (ASTM D445) in the range of 1 to 25 mm2 / s. Especially preferably, it is the range of 3-15. This range is preferable in that the charged particles can be moved at the time of the phenomenon, and have sufficient volatility, and the carrier liquid can be easily removed from the medium on which the final image is formed in the fixing step.
If the kinematic viscosity is less than 1 mm 2 / s, the liquid developer has a low viscosity, so that the transfer property to the developing roller is low, and a sufficient image density may not be obtained. Further, since the toner particles after development are likely to move, the fineness of the image may be easily lost. On the other hand, if the kinematic viscosity is greater than 25 mm 2 / s, the fluidity of the toner particles cannot be obtained and electrophoresis is difficult to occur, and a sufficient image density may not be obtained. Furthermore, since the permeability to a substrate such as paper is low, it is difficult to remove the carrier liquid when the toner particles are fixed, and sufficient fixability may not be obtained. In particular, the fixability in a superimposed image may be greatly reduced.

  Particularly preferred carrier liquids (D) are branched paraffin solvent mixtures, in particular isoparaffinic hydrocarbons or “Exol”, such as, in particular, the trade name “Isopar ™ M” (Exxon Mobil Corporation). Preferably, it is a naphthenic hydrocarbon such as D110 "," Exol D130 "(Exxsol ™) (Exxon Mobil Corporation).

(Other additives)
(Pigment dispersant)
Examples of pigment dispersants that are internally added to the toner particles include polyamine-based resin-type dispersant Solsperse 24000SC, Solsperz 32000 (manufactured by Lubrizol Corp.), Azisper PB821 (manufactured by Ajinomoto Fine-Techno Corp.), and acrylic copolymer resin-type dispersant BYK-116 (manufactured by Big Chemie) or the like can be used. In particular, when it is produced through a colored master batch having a high pigment concentration, it is preferably added 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).

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

  As the positive charge control agent, quaternary ammonium salt compounds (for example, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylbenzylammonium tetrafluoroborate), quaternary ammonium salt organic tin oxide (for example, dibutyltin) Oxide, dioctyltin oxide, dicyclohexyltin oxide), diorganotin borate (eg, dibutyltin borate, dioctyltin borate, dicyclohexyltin borate), an electron donating substance such as a polymer having an amino group, or a combination of two or more. Can be used. Needless to say, the triarylmethane dye described above is preferable.

Further, instead of using the charge control agent, a resin charge control agent can be used.
For positive charging, if it is shown as an example of styrene-butyl acrylate,
Formula _{- {CH 2 -CH (C 6} H 5)} a- {CH 2 -CH (COOC 4 H 9)} b- {CH 2 -C (CH 3) COOC 2 H 4 N + CH 3 (C 2 H ₅ ) ₂ CH ₃ (C ₆ H ₄ ) SO ₃ —} c
(Of these, the quaternary ammonium salt part (c) is 3 to 35% by mass, the styrene part (a) and the acrylic part (b) are 97 to 65% by mass, and the values of a, b and c are thereby determined. And a styrene-acrylic polymer copolymerized with a styrene-acrylic resin using a quaternary ammonium salt as a functional group.
Specifically, 2-ethylhexyl acrylate / acryloylamino-2-methyl-1-propanesulfonic acid / styrene copolymer, butyl acrylate / N, N-diethyl-N-methyl-2- (methacryloyloxy) ethyl Ammonium = p-toluenesulfonate / styrene copolymer and the like. 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 1.0 to 20 parts by mass, 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 of the present invention will be described.
The liquid developer of the present invention is preferably obtained through the following five processes.

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

(2) Preparation of toner particle chips (dilution of colored master batch)
The colored masterbatch obtained in (1) and the binder resin (A) are mixed with a mixer such as a super mixer, preliminarily dispersed, and then melt-kneaded, whereby the colored masterbatch is bound to the binder resin (A). Diluted in and developed to obtain a chip for toner particles. At the time of performing preliminary dispersion and melt-kneading here, a pigment dispersant, a polymer dispersant (C), a charge control agent, and the like may be added. Further, it is preferable that the toner particle chip has a particle size of 10 mm or less by rough crushing with a hammer mill, a sample mill or the like.
In addition, the steps (1) and (2) can be integrated. In that case, all steps during the preliminary dispersion in the step (2) without passing through the coloring masterbatch step (1). The material may be charged to produce a toner particle chip. As the melt-kneading, a known kneader such as a pressure kneader, a 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 7 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 or a kryptron.

(4) Wet pulverization of toner particles The dry pulverized toner particles obtained in (3) are developed in a solvent having the same composition as that of the carrier liquid (D), and the average particle size is measured using a wet pulverizer (disperser). Is pulverized to a range of 0.5 to 4 μm, preferably 1 to 3 μm. At this time, it is also effective to add a polymer dispersant (C) having a function of adsorbing the toner particles. Through the wet pulverization and dispersion steps, the dispersant is adsorbed in the toner particles and stabilized in terms of charging.
When performing wet pulverization (dispersion), it is desirable to cool so that the temperature during pulverization does not exceed 50 ° C. When the temperature exceeds 50 ° C., the toner particles are fused, and the particle size distribution cannot be controlled.

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

  In the wet pulverizer used in the present invention, the major factors that determine the pulverizability include the type of pulverizing media, the particle size of the pulverizing media, the filling rate of the dispersion media in the pulverizer, the type of agitator disk, and the solution of the sample to be pulverized. Concentration, type of solvent, etc. 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 weight, NaO 12 to 16% by weight, etc.), zircon beads (ZrO2 weight 69) according to the viscosity, specific gravity, required particle size of grinding and dispersion, and the like. %, SiO2 weight 31%), zirconia beads (ZrO2 weight 95% or more), alumina (Al2O3 weight 90% or more), titania (TiO2 weight 77.7%, Al2O3 weight 17.4%), steel balls, etc. can be used. However, it is preferable to use zirconia beads or zircon beads in order to obtain good grindability.
The particle diameter (diameter) of the pulverization media can be used in the range of 0.1 mm to 3.0 mm, and in particular, the range of 0.3 to 1.4 mm is preferable. If it is smaller than 0.1 mm, the load in the pulverizer increases, and the toner particles may melt due to heat generation, making pulverization difficult. Moreover, when larger than 3.0 mm, sufficient grinding | pulverization may not be performed. The filling rate of the dispersion medium is preferably 40 to 85% by mass. If it exceeds 85 mass%, the load in the pulverizer increases, and the toner particles may melt due to heat generation, which may make pulverization difficult. Moreover, when it will be less than 40 mass%, a grinding | pulverization efficiency may fall and refinement | miniaturization may become difficult. When the concentration of toner particles in the slurry is high (concentration of 40 to 50% by mass), the filling rate is preferably 40 to 70% by mass.

  An agitator disk inside the wet pulverizer preferably used in the present invention is also important for controlling the pulverizability. The peripheral speed of the disk is preferably 4 to 16 m / s, and if it is less than 4 m / s, it takes time to grind. On the other hand, if it is higher than 16 m / s, heat is generated due to contact with the pulverized media (medium), and the toner particles may be fused. Examples of the material of the agitator disk include hardened steel, stainless steel, alumina, zirconia, polyurethane, polyethylene, and engineering plastic. Among them, zirconia is preferably used.

  Examples of the material of the grinding cylinder on the inner wall of the wet pulverizer include special hardened steel, stainless steel, alumina, zirconia, ZTA, glass, and polyethylene. Among them, it is preferable to use zirconia reinforced alumina ceramics called ZTA.

(5) Purification of liquid developer The material containing the toner particles, the carrier liquid, and the dispersant obtained by the wet pulverization obtained in (4) is further mixed with a carrier liquid and, if necessary, a dispersant, and mixed. The liquid developer is purified while controlling the concentration of toner particles.
A liquid developer in which toner particles are stably dispersed can be obtained by adding the dispersant to the material obtained in the step (4) together with a carrier liquid for adjustment.

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

  Further, toner particles having a particle size of 2 μm or less with respect to all toner particles are contained in an amount of 50% by volume or less, toner particles having a particle size of 1 to 3 μm are contained in an amount of 5 to 60% by volume, and the particle size is 5 μm or more The toner particles are more preferably 35% by volume or less from the viewpoint of development characteristics for obtaining color developability. When the amount of toner particles having a particle size of 2 μm or less is more than 50% by volume, the polymer dispersant (C) may be less adsorbed on the toner particles, and excellent storage stability may not be obtained. Furthermore, in the wet pulverization of toner particles, the pulverizability becomes low, and the viscosity control of the liquid developer may be difficult. If the amount of toner particles having a particle size of 5 μm or more exceeds 35% by volume, there may be problems such as insufficient image density and poor color development and color reproducibility. The toner particles having a particle diameter of 1 to 3 μm are preferably contained in an amount of 5 to 60% by volume in order to obtain dispersion stability of the toner particles and excellent storage stability over a long period of time.

  In the present invention, the concentration of the toner particles in the liquid developer is preferably 10 to 30% by mass with respect to 100% by mass of the liquid developer. More preferably, it is 12-25 mass%. When the amount is less than 10% by mass, it is difficult to remove the carrier liquid (D), and the fixability of toner particles may be lowered. When the amount is more than 30% by mass, the viscosity of the liquid developer increases, the mobility of toner particles decreases, and a sufficient image density may not be obtained. Further, the toner particles may be strongly aggregated and storage stability may be deteriorated.

  The liquid developer of the present invention preferably has a surface potential of 0.4 kV or more after 1 second of corona charging. The surface potential of the liquid developer was measured as follows. That is, the liquid developer sample is put in a black anodized aluminum container (a cylinder with a diameter of 40 mm and a height of 10 mm) and placed on a grounded metal plate. Set the distance to 10 mm. Corona discharge was performed for 10 seconds under an atmosphere condition of 25 ° C. and 50%, and immediately after that, measurement was performed using a surface potentiometer (conforms to JIS C 61340-2-1).

  The surface potential of the liquid developer is greatly influenced by the components constituting the liquid developer, and the binder resin (A) or the colorant (B) and unreacted compounds, by-products generated when they are synthesized, Alternatively, when the surface treatment agent of the colorant (B) is eluted into the carrier liquid (D), the insulating property of the liquid developer may be lowered and the surface potential may be lowered. When the surface potential after 1 second of corona charging is less than 0.4 kV, the charge amount of the toner particles becomes insufficient, and developability and transferability deteriorate. As a result, problems such as insufficient color reproducibility are caused due to the occurrence of fogging phenomenon and a decrease in the transfer efficiency of superposition.

The viscosity (η) of the liquid developer of the present invention is preferably 5 to 180 mPa · s, and the volume specific resistance is preferably 10 ¹⁰ to 10 ¹⁵ Ω · cm.
The viscosity (η) of the liquid developer can be measured using, for example, an E-type viscometer TV-22 manufactured by Toki Sangyo Co., Ltd. After adjusting the solid content in the liquid developer to 25% and fully acclimatizing to 25 ° C, set the 1 ° 34 'cone in the TV-22 type viscosity shape, and measure the viscosity after 1 minute at 20 rpm. Can be obtained. If the viscosity (η) is less than 5 mPa · s, the fineness of the image after development is lacking, and if it exceeds 180 mPa · s, the mobility of toner particles during development is reduced and high-speed development is not possible, and sufficient image density is obtained. Problems such as inability to occur.
The volume resistivity can be measured in the same manner as the carrier liquid measuring method described above. If it is 10 ¹⁰ Ω · cm or less, the electrostatic latent image on the photoreceptor cannot be retained, which is not preferable.

  In the use of the liquid developer of the present invention, a development process that can be preferably used is to supply the liquid developer to a developing roller made of conductive rubber, neutralize before transfer using an amorphous silicon photoconductor exposed to LED, Development is preferably performed via a 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.

  The printed matter printed with the liquid developer is not particularly limited, but is used for general commercial use, paper package, packaging film, seal / label use and the like. For example, for general commercial use, high-quality paper, catalogs and magazines such as coated paper, magazines, etc., for paper packaging, packaging containers and outer boxes using coated paper or cardboard, and PET for packaging films Examples thereof include flexible packaging containers using sheets and PP sheets.

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, “parts” are all “unless otherwise noted”.
"Parts by mass". However, Examples 1, 2, 4 to 6 are reference examples.

  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. The resulting binder resin had a softening temperature (T4) of 112 ° C. and a weight average molecular weight (Mw) of 11,000.

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

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

(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 was introduced with stirring, and the mixture was further heated to the boiling point of toluene, and 2 mixed solutions containing styrene monomers, acrylic esters, and di-t-butyl peroxide as a polymerization initiator shown in Table 2 were obtained. Solution polymerization was carried out while dropping over time. After completion of the dropwise addition, the reaction was further continued at the boiling point of toluene for 2 hours, and 1 part of di-t-butyl peroxide was added to terminate the polymerization. Next, it heated up to 180 degreeC and toluene was removed, and the binder resin 2 containing a polyester resin and a styrene-acryl copolymer resin was obtained. The resulting binder resin had a softening temperature (T4) of 120 ° C. and a weight average molecular weight (Mw) of 12,800.

(Synthesis example 1 of polymer dispersant)
Into a reaction vessel equipped with a nitrogen gas introduction tube, a thermometer, a condenser, and a stirrer, 90.1 parts of Exol D110 (naphthenic hydrocarbon solvent, manufactured by ExxonMobil) was charged and replaced with nitrogen gas. The reaction vessel was heated to 110 ° C., 20.0 parts of N, N-dimethylaminoethyl methacrylate, 60.0 parts of stearyl methacrylate, polyethylene glycol mono (meth) acrylate monomethyl ether (in the general formula (1), R ¹ = CH ₃ ) 20.0 parts, and 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 for 2 hours Over the course of the 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 resulting polymer dispersant 1 had an amine value of 65 mg KOH / g and a weight average molecular weight (Mw) of 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 1 solution so that the nonvolatile content of the polymer dispersant solution was 50 mass%. As a result, a 50% by mass solution of the polymer dispersant 1 with a nonvolatile content was obtained.

(Synthesis example 2 of polymer dispersant)
Synthesis was performed in the same manner as in Synthesis Example 1 except that the raw materials and preparation amounts shown in Table 3 were used, and a polymer dispersant 2 solution was obtained. The resulting polymer dispersant 2 had an amine value of 65 mg KOH / g and a weight average molecular weight (Mw) of 6,940. Exol D110 was added so that the nonvolatile content of the polymer dispersant solution was 50% by mass. As a result, a 50% by mass solution of the polymer dispersant 2 with a nonvolatile content was obtained.

In the table: DM: N, N-dimethylaminoethyl methacrylate SMMA: stearyl methacrylate C-1: R ¹ = CH _{3 in the} general formula (1)

(Coloring agent)
Yellow colorant C.I. I. Pigment Yellow 185 (Isoindoline Yellow)
Paliotor Yellow D1155 (BASF)
C. I. Pigment Yellow 74 (Monoazo Yellow)
Fast Yellow 7415 (manufactured by Sanyo Dye)
C. I. Pigment Yellow 12 (Disazo Yellow)
Parment Yellow DHG (manufactured by Clariant)
Magenta colorant C.I. 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.)
C. I. Pigment Red 57: 1 (Kermin 6B)
Permanent Rubin L6B (manufactured by Clariant)
Cyan colorant C.I. I. Pigment Blue 15: 3 (copper phthalocyanine blue)
Lionol Blue FG7919 (Toyo Color)

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

(Carrier liquid)
Exol D130 Naphthenic hydrocarbon (manufactured by ExxonMobil)
Dry point: 313 ° C. Aniline point: 89 ° C. Kinematic viscosity: 6.12 mm ² / s
Density: 0.824 g / cm ³

(Preparation of liquid developer)
C. I. Pigment Yellow 185
Paliotor Yellow D1155 (manufactured by BASF) 18 parts by weight binder resin 1 80 parts by weight Solspers 24000SC 2 parts by weight After mixing the above materials (total 5 kg) with a Henschel mixer having a volume of 20 L (3,000 rpm, 3 minutes) The mixture was melt-kneaded with a twin-screw kneading extruder (PCM30) at a supply rate of 6 kg / hr and a discharge temperature of 145 ° C., and further kneaded with three rolls having a roll temperature of 140 ° C. After cooling and solidifying, coarsely pulverized with a hammer mill and then finely pulverized with an I-type jet mill (IDS-2 type) to obtain a yellow pulverized product 1 having an average particle diameter of 5.0 μm.

further,
Yellow pulverized product 1 25 parts by weight Exol D130 72 parts by weight Polymer dispersant 1 3 parts by weight were weighed and mixed thoroughly to disperse Yellow pulverized product 1 in the Exol D130 solution (slurry concentration was 25 masses). %).
The slurry in which the yellow pulverized product 1 is dispersed is subjected to a circulation operation for 60 minutes using a wet pulverizer which is a medium agitating mill, Dino Mill Multilab (Shinmaru Enterprises Co., Ltd., capacity 1.4 L), and wet pulverization is performed. went.
The wet pulverization conditions at this time were as follows.
Agitator disk (material: zirconia) peripheral speed 10 m / s, cylinder ZTA, media (material: zirconia) diameter 1.25 mm, filling rate 70%, solution flow rate 45 kg / h, cooling water 5 L / min, pressure 0.1 kg / cm ²
After wet pulverization for 60 minutes, the slurry was taken out and passed through a mesh having a mesh size of 33 μm (manufactured by SUS304) to obtain a yellow liquid developer 1Y (including yellow toner particles 1). When the particle size distribution of the yellow toner particles 1 was confirmed, the average particle size (D50) was 2.6 μm.

The raw materials shown in Tables 4 and 5 were prepared using the same method as that for the yellow liquid developer 1Y so that the average particle diameter of the toner particles and the toner particles in the liquid developer were 2.6 μm or less, respectively. . The particle size was measured using a Nikkiso Laser Diffraction and Scattering Particle Size Analyzer Microtrac HRA, the solvent using Exol D80 (Exxsol ^™ ) Exxon Mobil Corporation, and at 23 ° C. and 50% RH environmental conditions. The average particle size (D50) is a cumulative 50 percent diameter value.

(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 evaluation of image density and fixing rate. At this time, single color images are produced with solid colors of yellow, magenta, and cyan, and red (yellow x magenta), blue violet (magenta x cyan), and green (cyan x yellow) are overlaid with monochromatic solid images. After that, 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.

(Colorimetry)
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. (Yellow, Magenta, Cyan) and single color solid overprinted part (Yellow x Magenta, Magenta x Cyan, Cyan x Yellow) A total of 6 colors a * vs. b * should be expressed as a plotted hexagonal area. Is possible. The larger the gamut area, the wider the color reproduction area.

Generally, it is practically preferable that 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, 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 1.0 to 1.1 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 sample is L * of a single color (yellow, magenta, cyan) and a superimposed secondary color (yellow x magenta, magenta x cyan, cyan x yellow) by X-Rite 504 (filter Status-T). , A *, b * values were measured. The results are shown in Table 6, and the gamut is shown in FIGS.

(Surface potential)
The surface potential of the liquid developer was measured with a surface potential meter immediately after charging the particles by corona discharge for 10 seconds. The value one second after the end of charging by corona discharge was taken as the surface potential of the liquid developer. If the surface potential after 1 second is 0.4 kv or more, it is practically preferable, and if it is 0.6 kv or more, it is more preferable.

(Cover)
Evaluation of occurrence of “fogging phenomenon” in which toner particles are transferred not only to an image portion but also to a non-image portion was performed by measuring reflectance with a photovolt 577. If it is less than 1.0%, it is practically preferable, and if it is less than 0.5, it is more preferable.

◎: Reflectance is less than 0.5 ○: Reflectance is 0.5% or more and less than 1.0% Δ: Reflectance is 1.0% or more and less than 1.5% ×: Reflectance is 1.5% that's all

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

A: Fixing rate is 90% or more B: Fixing rate is 80% or more and less than 90% X: Fixing rate is less than 80%

(Overlay transfer efficiency measurement)
The liquid developer layer of the photosensitive member before and after the passage of the liquid developer from the photosensitive member to the intermediate transfer member at the time of overprinting of the superposed color is collected with a tape and attached on a paper, and then X-Rite 504 The concentration was measured.
The transfer efficiency of superimposition was determined by (density before passage) / ((density before passage) + (density after passage)) × 100. The transfer efficiency is desirably 90% or more if practical, and more preferably 95% or more. The measurement results are shown in Table 7.

◎: Transfer efficiency is 95% or more ○: Transfer efficiency is 90% or more and less than 95% ×: Transfer efficiency is less than 90%

Detailed test results are shown in Table 7.

In Comparative Examples 21 and 22, since Pigment Yellow 185 is not used, the b * value of yellow is small, and the color gamut of the red and green regions is narrow. In Comparative Examples 23 and 24, the transfer efficiency at the time of overlapping is poor, Since the color gamut of the red or blue violet region is narrow, sufficient color reproducibility cannot be obtained. Further, in Comparative Examples 21 and 24, fog occurs in the monochromatic output image.
On the other hand, in the example, a printed matter with no fog and excellent color reproducibility was obtained. In particular, in Examples 3 and 7, printed matter having a wide color gamut in the red region and excellent in color reproducibility was obtained.

  The liquid developer set according to an embodiment of the present invention is excellent in color reproducibility without fogging, and is an electronic copying machine, printer, on-demand printing 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 in a machine or the like.

Claims (9)

At least a liquid developer set having a plurality of liquid developers composed of a binder resin (A), a colorant (B), a polymer dispersant (C), and a carrier liquid (D),
At least the colorant (B) is C.I. I. Pigment Yellow 185, a yellow liquid developer, and the colorant (B) are C.I. I. A liquid developer set comprising a magenta liquid developer containing CI Pigment Red 150. The mass ratio [binder resin (A) / colorant (B)] of the binder resin (A) to the colorant (B) in all of the plurality of liquid developers is 2.6-12. The liquid developer set according to claim 1. 3. The liquid developer set according to claim 1, wherein the binder resin (A) in all of the plurality of liquid developers includes at least a polyester resin. 4. Binder resin of the magenta liquid developer (A) is a polyester resin, styrene resin, or acrylic resin, or styrene - characterized in that it comprises an acrylic copolymer resin, according to any one of claims 1 to 3 Liquid developer set. The softening temperature of the entire binder resin (A) in all of the plurality of liquid developers is 80 to 140 ° C., and the weight average molecular weight Mw is 2000 ≦ Mw ≦ 100,000. 4. The liquid developer set according to any one of 4 above. The polymer dispersant (C) in all of the plurality of liquid developers contains at least an ethylenically unsaturated monomer having an amino group and an ethylenically unsaturated monomer having 9 to 24 carbon atoms. preparative be copolymerized, claim 1-5 liquid developer set according any one, wherein the amine value of 5~150mgKOH / g. Polymeric dispersant in all of the plurality of liquid developing agent (C) is at least one of claims 1 to 6, characterized in that by copolymerizing the ethylenically unsaturated monomers of the following general formula (1) Or a liquid developer set.
General formula (1)
CH ₂ = C (R ¹ ) COO (AO) nR ²
Wherein R ¹ is H or CH ₃ , R ² is hydrogen or a hydrocarbon group having 1 to 22 carbon atoms, and n is 1
An integer of ˜200, A represents an alkylene group having 2 to 4 carbon atoms. ) The weight average molecular weight Mw of the polymeric dispersing agent (C) in all the plurality of liquid developers, claim 1-7 liquid developer set according any one, which is a 500 ≦ Mw ≦ 40000. Carrier liquid in all the plurality of liquid developers (D) is, the liquid developer set according to any one of claims 1-8, characterized in that the aliphatic hydrocarbon.

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