JP2015001711A - Liquid developer set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid developer set in which a black developer including nigrosine and a chromatic color developer can be fixed in the same temperature conditions, and the black developer and chromatic color developer have the same fixing quality.SOLUTION: There is provided a liquid developer set that includes a black developer including first toner particles and a chromatic color developer including second toner particles, where the first toner particles include a first polyester resin, black colorant, and nigrosine, and the second toner particles include a second polyester resin and chromatic color colorant, and the first toner particles and second toner particles satisfy the formula Mc(1-2a)<Mk<Mc(1-0.5a), where Mk represents the number average molecular weight of the first polyester resin; Mc represents the number average molecular weight of the second polyester resin and 10000≤Mc≤50000; and a represents the mass ratio of nigrosine and 0.01≤a≤0.20.

Description

  The present invention relates to a liquid developer set.

  Various liquid developers (also called wet developers) used in electrophotographic image forming apparatuses are known. For example, Japanese Patent Application Laid-Open No. 2011-27845 (Patent Document 1) is a liquid developer containing toner particles and a carrier liquid, and the toner particles contain a binder resin and a colorant, and the colorant is nigrosine. A liquid developer containing a pigment is disclosed.

JP 2011-27845 A

  The liquid developer has a feature that the particle size of toner particles is about 0.5 μm to 3 μm, and the particle size of toner particles is smaller than that of a dry developer. As a result, the liquid developer can achieve high image quality while reducing the adhesion amount of toner particles.

  In electrophotographic color image formation, a liquid developer set including a black developer and a chromatic developer such as a cyan developer is used. That is, a plurality of color liquid developers are simultaneously used in the image forming apparatus, and a color image is formed on the recording material by superimposing, transferring, and fixing the toner images of the respective colors onto the recording material.

  In consideration of such usage as a liquid developer set, the liquid developer of each color included in the liquid developer set can be fixed under the same temperature condition and has the same fixing quality between the color materials. Is desirable.

  However, as described below, in the prior art, the black developer and the other chromatic color developer are fixed at the same temperature condition, and the black developer and the other chromatic color developer have the same fixing quality. It was very difficult to have.

  As described above, the toner particles of the liquid developer have a smaller particle size than that of the dry developer, and can reduce the amount of adhesion. In order to maintain, it is necessary to set the colorant content of the toner particles high.

  Carbon black is widely used as a colorant for black developers. However, when the content of carbon black in the toner particles increases, the electrical resistance of the toner particles decreases, and the electrical characteristics required for electrophotographic image formation sometimes deteriorate.

  Conventionally, in order to prevent such a problem, an attempt has been made to use an organic colorant in combination with carbon black as a black colorant. However, the organic colorant has a weak coloring power as “black”, and when the addition amount is increased to compensate for this, the hue also deviates from “black”. Therefore, it has been proposed to add nigrosine, which is a purple black dye, to the black colorant in order to adjust the hue shift.

  On the other hand, from the viewpoint of lowering the fixing temperature, a crystalline resin such as a crystalline polyester resin has been proposed as a resin constituting the toner particles. As described above, since the resin constituting the toner particles is crystalline, there is an advantage that a property of being rapidly melted at a specific temperature, that is, a sharp melt property is imparted in fixing at a low temperature.

  However, when the black toner particles are composed of a crystalline resin and a black colorant containing nigrosine, the fixing temperature of the black toner particles is shifted to a high temperature side. And this tendency is so remarkable that the addition amount of nigrosine is increased. Although the details of the mechanism of this phenomenon are unknown, it is believed that nigrosine delays crystallization of the resin in some form.

  Therefore, when a liquid developer set is composed of a black developer containing nigrosine and other chromatic color developer, there is a difference in fixing temperature between black and other color materials, as well as fixing quality such as glossiness and fixing strength. Variation will also occur. So far, there has been no example in which sufficient solution means has been reported for such a problem as a liquid developer set.

  The present invention has been made in view of such a current situation, and an object of the present invention is to allow black developer containing nigrosine and chromatic color developer to be fixed under the same temperature condition, and black development. Another object of the present invention is to provide a liquid developer set in which the developer and the chromatic color developer have the same fixing quality.

  Conventionally, as a means for adjusting the fixing temperature of toner particles, a method of adjusting the molecular weight of a constituent resin of toner particles is known. However, when the present inventor tried to match the fixing temperature of the black toner particles and the chromatic toner particles by this means, the molecular weight of the resin is decreased in order to lower the fixing temperature of the black toner particles containing nigrosine. A new problem was encountered in that the carrier liquid easily enters between the resin and the strength of the toner film after fixing decreases.

  However, the present inventor is not limited to this, and means for adjusting the fixing temperature of the black toner particles and the chromatic toner particles without changing the resin type, the molecular weight, the addition amount of nigrosine, etc. to reduce the fixing strength of the black toner particles. As a result of intensive studies, we obtained knowledge that the above problems could be solved by adjusting the molecular weight of the resin constituting the black toner particles in accordance with the amount of nigrosine added, and further studies were made based on this knowledge. Therefore, when the resin molecular weight of the black toner particles, the resin molecular weight of the chromatic toner particles, and the amount of nigrosine added to the black toner particles satisfy a specific relationship, fixing is possible under the same temperature condition and excellent fixing quality. And the present invention has been completed.

  That is, the liquid developer set of the present invention is a liquid developer set including a black developer including first toner particles and a chromatic color developer including second toner particles, and the first toner particles include 1 polyester resin, a black colorant and nigrosine, and the second toner particles include a second polyester resin and a chromatic colorant and satisfy the following formula (1).

Mc (1-2a ^0.5 ) <Mk <Mc (1-0.5a ^0.5 ) (1)
Here, in the formula (1), Mk represents the number average molecular weight of the first polyester resin, Mc represents the number average molecular weight of the second polyester resin, 10000 ≦ Mc ≦ 50000, and a is the above-mentioned nigrosine. The mass ratio with respect to the total solid content contained in the black developer is shown, and 0.01 ≦ a ≦ 0.20.

  Here, the first polyester resin and the second polyester resin include a common structural unit in the molecular structure, and the common structural unit accounts for 80% or more of the total structural units in each molecular structure. It is preferable that the first polyester resin and the second polyester resin are substantially the same polymer species.

  Further, the first polyester resin and the second polyester resin are preferably crystalline resins having heats of fusion by differential scanning calorimetry satisfying the following formulas (2) and (3), respectively.

5 ≦ H1 ≦ 70 (2)
0.2 ≦ H2 / H1 ≦ 1.0 (3)
Here, in the formulas (2) and (3), H1 represents the heat of fusion (J / g) at the time of the first temperature rise by differential scanning calorimetry, and in formula (3), H2 is from the differential scanning calorimetry. The heat of fusion (J / g) during the second temperature increase is shown.

  The first polyester resin and the second polyester resin are each preferably a urethane-modified polyester resin in which at least two or more polyesters are bonded by a structural unit derived from a compound having an isocyanate group.

  Further, the liquid developer set preferably satisfies the following condition 1 and / or condition 2.

  Condition 1: The first toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surface of the core particles containing the core resin, and the core resin is the first polyester resin. is there.

  Condition 2: The second toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surfaces of core particles containing a core resin, and the core resin is the second polyester resin. is there.

  In the liquid developer set, the chromatic colorant is preferably a cyan pigment.

  Since the liquid developer set of the present invention has the above-described configuration, the black developer containing nigrosine and the chromatic developer can be fixed under the same temperature condition, and the black developer and the chromatic color can be fixed. It has an excellent effect that the developer has the same fixing quality.

1 is a schematic conceptual diagram of an electrophotographic image forming apparatus.

Hereinafter, embodiments according to the present invention will be described in more detail.
<Liquid developer set>
The liquid developer set of the present embodiment includes a black developer and a chromatic developer. Here, at least one chromatic color developer is included, and a plurality of chromatic color developers may be included.

  Here, the chromatic color means a color other than black, white, and gray. Typical examples of such chromatic colors include cyan, magenta, yellow, and the like.

<Liquid developer>
The liquid developer included in the liquid developer set of the present embodiment includes at least an insulating liquid (carrier liquid) and toner particles, and the toner particles are dispersed in the insulating liquid. Such a liquid developer can contain other arbitrary components as long as these components are contained. Other components include, for example, a toner dispersant (in contrast to a pigment dispersant described later contained in the toner particles, a dispersant contained in the insulating liquid for dispersing the toner particles. And a charge control agent, a thickener, and the like.

  The mixing ratio of the liquid developer can be, for example, 10 to 50% by mass of toner particles, and the remainder can be an insulating liquid or the like. If the blending amount of the toner particles is less than 10% by mass, the toner particles are likely to settle, and the stability over time during long-term storage tends to decrease. In addition, a large amount of liquid development is required to obtain the required image density. It is necessary to supply the agent, the amount of the insulating liquid adhering to the recording material such as paper increases, it becomes necessary to dry it at the time of fixing, and the generated vapor may cause environmental problems. is there. On the other hand, when the blending amount of the toner particles exceeds 50% by mass, the viscosity of the liquid developer becomes too high, which tends to be difficult in production and handling.

  Such a liquid developer is useful as a developer for an electrophotographic image forming apparatus. More specifically, electrophotographic liquid developers, paints, electrostatic recording liquid developers, and ink jet printers used in electrophotographic image forming apparatuses such as copying machines, printers, digital printing machines, and simple printing machines. It can be used as an oil-based ink or an electronic paper ink.

<Toner particles>
The toner particles contained in the liquid developer include a resin and a colorant dispersed in the resin. Such toner particles can contain any other component as long as these components are contained. Examples of other components include pigment dispersants, waxes, charge control agents, and the like. Here, the blending ratio of the resin and the colorant may be determined so that the concentration expressed when the toner particles are applied in a desired adhesion amount becomes a desired concentration.

  In the present embodiment, the median diameter of the toner particles is preferably 0.5 μm or more and 5.0 μm or less. Such a median diameter is smaller than the particle diameter of toner particles of a conventional dry developer, which is one of the features of the present embodiment. However, when the median diameter is less than 0.5 μm, the particles are If the diameter is too small, the mobility in the electric field may be deteriorated and the developability may be deteriorated. If it exceeds 5 μm, the uniformity may be deteriorated and the image quality may be deteriorated. The median diameter here refers to D50. A more preferable median diameter is 0.5 μm or more and 2.0 μm or less.

  In the exemplary embodiment, the average circularity of the toner particles is preferably 0.85 or more and 0.95 or less, and the standard deviation of the circularity is preferably 0.01 or more and 0.1 or less. This is because the average circularity of the toner particles and the standard deviation of the circularity occupy such a range, thereby providing an effect of improving transferability and cleaning properties.

  The circularity referred to here is a numerical value obtained by dividing the perimeter of a circle having the same area as the particle area projected in two dimensions by the perimeter of the particle, and the average circularity is an arithmetic average value of the numerical values. Is shown.

  In the present embodiment, the median diameter, average circularity, and standard deviation of circularity of toner particles are all determined using a flow particle image analyzer (trade name: “FPIA-3000S”, manufactured by Sysmex Corporation). Can do. This apparatus is preferable because the insulating liquid can be used as a dispersion medium as it is, and thus the state of particles in an actual dispersion state can be measured as compared with a system in which measurement is performed in an aqueous system.

<Black developer and chromatic developer>
In the present embodiment, the black developer includes first toner particles, and the first toner particles include a first polyester resin, a black colorant, and nigrosine. The chromatic developer includes second toner particles, and the second toner particles include a second polyester resin and a chromatic colorant.

<First polyester resin and second polyester resin>
In the present embodiment, the first polyester resin and the second polyester resin have the number average molecular weight of the first polyester resin as Mk, the number average molecular weight of the second polyester resin as Mc, and the total solid content contained in the black developer. When the mass ratio of nigrosine to is a, the following formula (1) is satisfied.

Mc (1-2a ^0.5 ) <Mk <Mc (1-0.5a ^0.5 ) (1)
As described above, the liquid developer set according to the present embodiment includes the molecular weight of the polyester resin constituting the black toner particles (first toner particles) and the chromatic toner according to the mass ratio of nigrosine contained in the black developer. By adjusting the molecular weight of the polyester resin constituting the particles (second toner particles) so as to satisfy a specific relationship, the black developer containing nigrosine and the chromatic developer can be fixed under the same temperature condition. In addition, an excellent effect that the black developer and the chromatic color developer have the same fixing quality is exhibited.

  Here, in said formula (1), Mc needs to be 5000 or more and 50000 or less. This is because if the Mc is less than 5000, the polyester resin becomes excessively soft, and therefore offset tends to occur. If it exceeds 50000, the polyester resin is difficult to melt, and the fixing strength tends to decrease. Because. In addition, the more preferable range of Mc is 10,000 or more and 30000 or less.

  In the present embodiment, the first toner particles contain nigrosine. And in said Formula (1), a needs to be 0.01 or more and 0.2 or less, Preferably it is 0.03 or more and 0.15 or less. This is because when a is less than 0.01, a desired image density tends to be difficult to obtain, and when it exceeds 0.20, the effect of crystallization delay by nigrosine increases, and the black toner particles are fixed by adjusting the molecular weight. This is because it is difficult to match the temperature and the fixing temperature of the chromatic toner particles.

In the above formula (1), if Mk exceeds Mc (1-0.5a ^0.5 ), the fixing temperature of the black toner particles becomes higher than that of the chromatic toner particles, and the black toner particles are difficult to melt at the time of fixing. The desired glossiness cannot be obtained as a liquid developer set. On the other hand, if Mk is lower than Mc (1-2a ^0.5 ), the molecular weight of the resin constituting the black toner particles becomes excessively low, and the carrier liquid is easily taken up between the resins. As a result, the toner film strength of the black toner particles is lower than the toner film strength of the chromatic color toner particles, so that a desired fixing strength cannot be obtained as a liquid developer set. Therefore, the liquid developer set of the present embodiment needs to satisfy the above formula (1).

  As the liquid developer set of the present embodiment, for example, a liquid developer set in which the relationship of the above formula (1) is satisfied between a black developer and a cyan developer, that is, a chromatic colorant is a cyan pigment. And a liquid developer set. In practice, since a black developer and a cyan developer are frequently used as a set, a liquid developer set satisfying the above relationship at least between the black developer and the cyan developer is This is one of the preferred aspects of the embodiment.

  However, in the present embodiment, when the liquid developer set includes a plurality of chromatic color developers, the relationship of the above formula (1) between any one or more chromatic color developers and the black developer. If the condition is satisfied, the effect of the present invention is shown. In addition, as long as the black developer and at least one chromatic color developer satisfy the above relationship, even if a chromatic color developer that does not satisfy the above relationship is included, the scope of the present invention is satisfied. It does not deviate.

<Urethane modified polyester resin>
In the present embodiment, the first polyester resin and the second polyester resin are preferably urethane-modified polyester resins. Here, the urethane-modified polyester resin is a resin having a structure in which the end of the polyester is chain-lengthened with a urethane bond. That is, the urethane-modified polyester resin is a resin in which at least two or more polyesters are bonded by a structural unit derived from a compound having an isocyanate group. Such a urethane-modified polyester resin is obtained by first obtaining a polyester resin as a skeleton by polymerization, and chain-extending the terminal of the polyester resin with di (tri) isocyanate. Di (tri) isocyanate means diisocyanate and / or triisocyanate.

  By using a urethane-modified polyester resin as the first polyester resin and the second polyester resin, an excellent effect of increasing the toughness of the resin and improving the offset resistance and the fixing strength is imparted.

  Here, the number average molecular weight (Mk) of the first polyester resin and the number average molecular weight (Mc) of the second polyester resin are, for example, a polycarboxylic acid component when synthesizing a polyester resin that is a raw material of a uretan-modified polyester resin. Equivalent ratio ([acid group] / [hydroxyl group]) of the acid group amount of the polyol component and the hydroxyl group amount of the polyol component, the isocyanate group amount of the compound having an isocyanate group for bonding the polyester resins together, and the hydroxyl group amount of the polyester resin And the equivalent ratio ([isocyanate group] / [hydroxyl group]) can be adjusted to a desired range.

<Number average molecular weight (Mn) and weight average molecular weight (Mw)>
In the present specification, the number average molecular weight (hereinafter also referred to as “Mn”) and the weight average molecular weight (hereinafter also referred to as “Mw”) of a resin (excluding a polyurethane resin) are allowed to be tetrahydrofuran (hereinafter abbreviated as “THF”). The dissolved content was measured using gel permeation chromatography (GPC (Gel Permeation Chromatography), hereinafter abbreviated as “GPC”) under the following conditions. The number average molecular weight (Mk) of the first polyester resin and the number average molecular weight (Mc) of the second polyester resin were measured by this method.

Measuring device: “HLC-8120” manufactured by Tosoh Corporation
Column: “TSKgelGMHXL” (2) manufactured by Tosoh Corporation and “TSKgelMultiporeHXL-M” (1) manufactured by Tosoh Corporation
Sample solution: 0.25 mass% THF solution Injection amount of sample solution to the column: 100 μl
Flow rate: 1 ml / min Measurement temperature: 40 ° C
Detector: Refractive index detector Reference material: 12 standard polystyrene (TSK standard POLYSTYRENE) manufactured by Tosoh Corporation (Molecular weight: 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000, 2890000).

  Moreover, in this specification, Mn and Mw of a polyurethane resin are measured on condition of the following using GPC.

Measuring device: “HLC-8220GPC” manufactured by Tosoh Corporation
Column: “TSK guardcolumn α” (1) manufactured by Tosoh Corporation and “TSKgel α-M” (1) manufactured by Tosoh Corporation
Sample solution: 0.125 mass% dimethylformamide solution Injection amount of dimethylformamide solution to the column: 100 μl
Flow rate: 1 ml / min Measurement temperature: 40 ° C
Detector: Refractive index detector Reference material: 12 standard polystyrene (TSK standard POLYSTYRENE) manufactured by Tosoh Corporation (Molecular weight: 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000, 2890000).

<Crystallinity>
In the present embodiment, the first polyester resin and the second polyester resin are preferably crystalline polyester resins. By using a crystalline polyester resin, a desired glossiness tends to be easily obtained at a low temperature, which is preferable.

  Here, in the present embodiment, the “crystalline” resin means the heat of fusion by differential scanning calorimetry (hereinafter, also referred to as “DSC (Differential scanning calorimetry)).” The following formulas (2) and (3) The resin which satisfy | fills is shown.

5 ≦ H1 ≦ 70 (2)
0.2 ≦ H2 / H1 ≦ 1.0 (3)
In formulas (2) and (3), H1 represents the heat of fusion (J / g) at the first temperature rise by differential scanning calorimetry, and in formula (3), H2 represents the second rise by differential scanning calorimetry. The heat of fusion (J / g) when warm is shown.

  In the present specification, heat of fusion of the first polyester resin and the second polyester resin by DSC is shown below using a differential scanning calorimeter (for example, product name: “DSC210”, manufactured by Seiko Instruments Inc.). It was measured according to conditions.

  That is, using standard polyester as a standard sample, the standard sample and the measurement target resin are heated from 0 ° C. to 180 ° C. at a rate of 10 ° C./min, and the difference between the heat amount of the standard sample and the measurement target resin is measured. . And the difference of the calorie | heat amount measured at this time is made into the heat of fusion by DSC of measurement object resin.

  In the above formula (2), H1 is an index of the melting rate of the polyester resin. In general, a resin having heat of fusion has a sharp melt property and can be melted with a small amount of energy. Therefore, if a resin having heat of fusion is selected as the first polyester resin and the second polyester resin, the energy required for fixing can be reduced. If the H1 of the first polyester resin and the second polyester resin exceeds 70, it is difficult to reduce the energy required for fixing, the fixability of the toner particles is lowered, and the adhesion to the medium (recording material) is lowered. However, this is not preferable because it causes a document offset. Further, if H1 is less than 5, the energy required for fixing becomes excessively small, and in this case also, document offset tends to occur. However, when H1 occupies the range of the above formula (2), it is possible to prevent the fixing property from being lowered and suppress the occurrence of document offset. Here, H1 is preferably 15 ≦ H1 ≦ 68, and more preferably 35 ≦ H1 ≦ 65.

  H2 / H1 in the above formula (3) is an index of the crystallization speed of the polyester resin. In general, when particles made of resin (resin particles) are melted and then cooled and used, if the crystal component in the resin particles is not crystallized, the resistance value of the resin particles decreases, or the resin There is a problem that the particles are plasticized. When such a malfunction occurs, the performance of the resin particles obtained by cooling may differ from the originally designed performance. From the above, it is necessary to quickly crystallize the crystal component in the resin particles so as not to affect the performance of the resin particles. H2 / H1 is more preferably 0.3 or more, and further preferably 0.4 or more. Further, if the crystallization speed of the polyester resin is high, H2 / H1 approaches 1.0. Therefore, H2 / H1 preferably takes a value close to 1.0.

  Note that H2 / H1 in the above formula (3) does not theoretically exceed 1.0, but it may exceed 1.0 in the actual measurement value by DSC. Even when the actual measurement value (H2 / H1) by DSC exceeds 1.0, the above equation (3) is satisfied.

  H1 and H2 can be measured according to JIS-K7122 (1987) “Method for measuring the transition heat of plastic”. Specifically, first, 5 mg of the measurement target resin is collected and placed in an aluminum pan. Using a differential scanning calorimeter (for example, product name: “RDC220”, manufactured by SII Nano Technology Inc., or product name: “DSC20”, Seiko Instruments Inc., etc.) The temperature (melting point) at the endothermic peak of the resin due to melting is measured at 10 ° C., and the area S1 of the endothermic peak is obtained. And H1 is computable from the area | region S1 of the calculated | required endothermic peak. After calculating H1, after cooling to 0 ° C. with a cooling rate of 90 ° C./min, the temperature (melting point) at the endothermic peak of the resin due to melting was measured at a rate of temperature increase of 10 ° C. per minute. The area S2 is obtained. And H2 is computable from the area | region S2 of the calculated | required endothermic peak.

  The resin having such crystallinity can be obtained by appropriately selecting the constituent components of the first polyester resin and the second polyester resin. From the viewpoint of improving crystallinity, it is preferable to use, for example, a monomer having a linear alkyl skeleton having 4 or more carbon atoms as a constituent component of the polyester resin. As such monomers, for example, aliphatic dicarboxylic acids and aliphatic diols are suitable. These are merely preferred examples, and may contain an aromatic dicarboxylic acid, an aromatic diol, or the like as long as crystallinity is exhibited.

  Hereinafter, the monomer which comprises the urethane-modified polyester resin which is a suitable example of a 1st polyester resin and a 2nd polyester resin is demonstrated.

  Preferred examples of the aliphatic dicarboxylic acid that is a starting material for the polyester resin include alkane dicarboxylic acids having 4 to 20 carbon atoms, alkene dicarboxylic acids having 4 to 36 carbon atoms, and ester-forming derivatives thereof. . More preferred aliphatic dicarboxylic acids are succinic acid, adipic acid, sebacic acid, maleic acid, fumaric acid and the like, or ester-forming derivatives thereof.

  Further, preferred as the aliphatic diol which is a starting material of the polyester resin is ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, or 1 , 10-decanediol.

  Next, a compound having an isocyanate group for making a urethane-modified polyester resin by bonding and linking polyester resins obtained by polymerizing the dicarboxylic acid monomer and the diol monomer as described above Will be described.

  As the compound having an isocyanate group of the present embodiment, a compound having a plurality of isocyanate groups in the molecule is preferable. Examples of such compounds include chain aliphatic polyisocyanates and cyclic aliphatic polyisocyanates.

  Examples of chain aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as “HDI”), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2, and the like. 4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2, Examples include 6-diisocyanatohexanoate, or a combination of two or more of these.

  Examples of the cycloaliphatic polyisocyanate include isophorone diisocyanate (hereinafter abbreviated as “IPDI”), dicyclohexylmethane-4,4′-diisocyanate (hereinafter also referred to as “hydrogenated MDI”), cyclohexylene diisocyanate, methylcyclohexyl. Silylene diisocyanate (hereinafter also referred to as “hydrogenated TDI”), bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, and 2,6-norbornane diisocyanate, Or these 2 or more types combined use etc. are mentioned.

  In the liquid developer set of the present embodiment, the closer the resin constituting the black toner particles (first toner particles) and the chromatic toner particles (second toner particles) is, the more remarkable the effect of the present invention is. It will be a thing. This is because the closer the first polyester resin and the second polyester resin are, the more precisely the fixing temperature, glossiness and fixing strength can be matched.

  Therefore, it is preferable that the first polyester resin and the second polyester resin have a common structural unit composed of the above-described monomers in each other's molecular structure, and more preferably, the common polyester The structural unit preferably occupies 80% or more of the total structural units in each molecular structure.

  And it is especially preferable that the first polyester resin and the second polyester resin are substantially the same polymer species. Here, “substantially the same polymer species” means that the main components constituting the polymer are equal, and as described above, the first polyester resin and the second polyester resin are common in the molecular structure. This means that the common structural unit occupies 90% or more of the total structural units in each molecular structure.

  Thus, when the first polyester resin and the second polyester resin are substantially the same polymer species and the monomer components constituting the resin are the same, the molecular weight of the polyester resin is, for example, a polycarboxylic acid component. And by adjusting the polymerization number of the polyol component, it can be controlled within a desired range. In addition, when the first polyester resin and the second polyester resin are urethane-modified polyester resins, in order to make substantially the same polymer species, the compounds having an isocyanate group for bonding the polyester resins to each other, It is necessary to use the same in the synthesis of the resin.

<Method for producing toner particles>
The toner particles (that is, the first toner particles and the second toner particles) in the present embodiment can be manufactured based on a conventionally known technique such as a granulation method or a pulverization method.

  Here, the pulverization method is a method in which a resin and a colorant such as a pigment are previously melt-kneaded and pulverized. Such pulverization can be performed in a dry state or in a wet state in an insulating liquid.

  In addition, the granulation method includes suspension polymerization method, emulsion polymerization method, fine particle aggregation method, method of adding a poor solvent to a resin solution to precipitate, spray drying method, etc. There is also a manufacturing method in which the resin composition of the toner particles is made into a core / shell structure with different resins.

  The method for producing toner particles of the present embodiment is not particularly limited, but in order to obtain toner particles having a small diameter and a sharp particle size distribution, it is preferable to employ a granulation method rather than a pulverization method. This is because highly meltable resins and highly crystalline resins are soft and difficult to grind even at room temperature. According to the granulation method, even such a resin is suitable because a desired particle size can be easily obtained.

  In addition, among the above production methods, the resin is dissolved in a good solvent to form a core resin solution, and the core resin solution is mixed with an interfacial tension modifier for a poor solvent having an SP value different from that of the good solvent. According to the method of forming a droplet by forming shear droplets and then volatilizing the good solvent to form the core resin fine particles, the shearing method, the difference in interfacial tension, or the interfacial tension modifier (shell resin fine particles) By adjusting, the particle size and shape of the toner particles can be controlled to a high degree, which is suitable as a method for obtaining toner particles having a desired particle size distribution and shape.

<Core-shell type toner particles>
Features such as the median diameter and circularity of toner particles, which is one of the preferred aspects of the present embodiment described above, are realized by the toner particles being core-shell type toner particles having a core-shell structure. Cheap.

  Therefore, the first polyester resin and / or the second polyester resin of the present embodiment may have a core-shell structure in which shell particles containing the shell resin are attached to or coated on the surface of the core particles containing the core resin. preferable.

  In other words, the liquid developer set of the present embodiment preferably satisfies the following condition 1 and / or condition 2.

  Condition 1: The first toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surface of the core particles containing the core resin, and the core resin is the first polyester resin.

  Condition 2: The second toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surface of the core particles containing the core resin, and the core resin is the second polyester resin.

  Hereinafter, the core-shell type toner particles will be described. In the following description, for convenience, the core / shell type toner particles may be referred to as toner particles (C), and the liquid developer containing the toner particles (C) may be referred to as liquid developer (X).

  The toner particles (C) have a structure in which the shell particles (A) containing the shell resin (a) are attached to or coated on the surfaces of the core particles (B) containing the core resin (b).

  Here, in the present embodiment, the core resin (b) is the first polyester resin and / or the second polyester resin, and the core particle (B) is the first toner particle and / or the second toner. Particles.

<Shell resin (a)>
The shell resin (a) in the present embodiment may be a thermoplastic resin or a thermosetting resin. Examples of the shell resin (a) include vinyl resin, polyester resin, polyurethane resin, epoxy resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, and polycarbonate resin. Etc. As the shell resin (a), two or more of the above listed resins may be used in combination.

  From the viewpoint that toner particles having a preferable shape can be easily obtained in the present embodiment, it is preferable to use at least one of a vinyl resin, a polyester resin, a polyurethane resin, and an epoxy resin as the shell resin (a). More preferably, at least one of a polyester resin and a polyurethane resin is used.

<Vinyl resin>
The vinyl resin may be a homopolymer obtained by homopolymerizing a monomer having a polymerizable double bond (a homopolymer containing a bond unit derived from a vinyl monomer), or a polymerizable double bond. It may be a copolymer obtained by copolymerizing two or more monomers having a bond (a copolymer containing a bond unit derived from a vinyl monomer). Examples of the monomer having a polymerizable double bond include the following (1) to (9).

(1) Hydrocarbon having a polymerizable double bond The hydrocarbon having a polymerizable double bond is, for example, an aliphatic hydrocarbon having a polymerizable double bond represented by the following (1-1) or the following (1 -2) is preferably an aromatic hydrocarbon having a polymerizable double bond.

(1-1) Aliphatic hydrocarbon having a polymerizable double bond An aliphatic hydrocarbon having a polymerizable double bond is, for example, a chain having a polymerizable double bond represented by the following (1-1-1). It is preferably a hydrocarbon or a cyclic hydrocarbon having a polymerizable double bond represented by the following (1-1-2).

(1-1-1) Chain hydrocarbon having a polymerizable double bond Examples of the chain hydrocarbon having a polymerizable double bond include alkenes having 2 to 30 carbon atoms (for example, ethylene, propylene, butene). , Isobutylene, pentene, heptene, diisobutylene, octene, dodecene or octadecene); alkadienes having 4 to 30 carbon atoms (for example, butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene or 1,7-octadiene) Etc.).

(1-1-2) Cyclic hydrocarbon having a polymerizable double bond Examples of the cyclic hydrocarbon having a polymerizable double bond include mono- or dicycloalkene having 6 to 30 carbon atoms (for example, cyclohexene, vinyl, etc.). Cyclohexene or ethylidenebicycloheptene); mono- or dicycloalkadiene having 5 to 30 carbon atoms (for example, cyclopentadiene or dicyclopentadiene) and the like.

(1-2) Aromatic hydrocarbon having a polymerizable double bond As an aromatic hydrocarbon having a polymerizable double bond, for example, styrene; hydrocarbyl of styrene (for example, alkyl having 1 to 30 carbon atoms) , Cycloalkyl, aralkyl and / or alkenyl) substituted (eg, α-methyl styrene, vinyl toluene, 2,4-dimethyl styrene, ethyl styrene, isopropyl styrene, butyl styrene, phenyl styrene, cyclohexyl styrene, benzyl styrene, crotyl) Benzene, divinylbenzene, divinyltoluene, divinylxylene or trivinylbenzene); and vinylnaphthalene.

(2) Monomers having a carboxyl group and a polymerizable double bond and salts thereof Examples of the monomer having a carboxyl group and a polymerizable double bond include unsaturated monocarboxylic acids having 3 to 15 carbon atoms. [For example, (meth) acrylic acid, crotonic acid, isocrotonic acid, cinnamic acid, etc.]; unsaturated dicarboxylic acid having 3 to 30 carbon atoms (anhydride) [for example, (anhydrous) maleic acid, fumaric acid, itaconic acid, (Anhydrous) citraconic acid or mesaconic acid, etc.]; monoalkyl (1-10 carbon atoms) ester of unsaturated dicarboxylic acid having 3 to 10 carbon atoms (for example, maleic acid monomethyl ester, maleic acid monodecyl ester, fumaric acid) Monoethyl ester, itaconic acid monobutyl ester, citraconic acid monodecyl ester, etc.). As used herein, “(meth) acryl” means acrylic and / or methacrylic.

  Examples of the salt of the monomer include alkali metal salts (for example, sodium salt or potassium salt), alkaline earth metal salts (for example, calcium salt or magnesium salt), ammonium salts, amine salts, and 4 A grade ammonium salt etc. are mentioned.

  The amine salt is not particularly limited as long as it is an amine compound. For example, primary amine salt (for example, ethylamine salt, butylamine salt or octylamine salt); secondary amine salt (for example, diethylamine salt or dibutylamine salt) ); Tertiary amine salts (for example, triethylamine salt or tributylamine salt) and the like.

  Examples of the quaternary ammonium salt include tetraethylammonium salt, triethyllaurylammonium salt, tetrabutylammonium salt and tributyllaurylammonium salt.

  Examples of the salt of the monomer having a carboxyl group and a polymerizable double bond include sodium acrylate, sodium methacrylate, monosodium maleate, disodium maleate, potassium acrylate, potassium methacrylate, monopotassium maleate. , Lithium acrylate, cesium acrylate, ammonium acrylate, calcium acrylate, and aluminum acrylate.

(3) Monomers having a sulfo group and a polymerizable double bond and salts thereof (4) Monomers having a phosphono group and a polymerizable double bond and salts thereof (5) Hydroxyl groups and a polymerizable double bond (6) Nitrogen-containing monomer having a polymerizable double bond Examples of the nitrogen-containing monomer having a polymerizable double bond include the following (6-1) to (6-4): The monomer to show is mentioned.

(6-1) Monomer having an amino group and a polymerizable double bond Examples of the monomer having an amino group and a polymerizable double bond include aminoethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate. , Diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, N-aminoethyl (meth) acrylamide, (meth) allylamine, morpholinoethyl (meth) acrylate, 4-vinylpyridine, 2-vinylpyridine, crotylamine N, N-dimethylaminostyrene, methyl-α-acetaminoacrylate, vinylimidazole, N-vinylpyrrole, N-vinylthiopyrrolidone, N-arylphenylenediamine, aminocarbazole, aminothiazole, aminoindole, aminopyrrole, Examples include minoimidazole and aminomercaptothiazole.

  The monomer having an amino group and a polymerizable double bond may be a salt of the monomers listed above. Examples of the salts of the monomers listed above include the salts listed as “Salts of the above monomers” in “(2) Monomers having a carboxyl group and a polymerizable double bond and their salts”. Can be mentioned.

(6-2) Monomer having an amide group and a polymerizable double bond Examples of the monomer having an amide group and a polymerizable double bond include (meth) acrylamide, N-methyl (meth) acrylamide, N -Butyl (meth) acrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide, N, N'-methylene-bis (meth) acrylamide, cinnamic acid amide, N, N-dimethyl (meth) acrylamide, N, N-dibenzyl (meth) acrylamide, (meth) acrylformamide, N-methyl-N-vinylacetamide, N-vinylpyrrolidone and the like can be mentioned.

(6-3) A monomer having 3 to 10 carbon atoms having a nitrile group and a polymerizable double bond As a monomer having 3 to 10 carbon atoms having a nitrile group and a polymerizable double bond, for example, (Meth) acrylonitrile, cyanostyrene, cyanoacrylate, and the like.

(6-4) Monomers having 8 to 12 carbon atoms having a nitro group and a polymerizable double bond As monomers having 8 to 12 carbon atoms having a nitro group and a polymerizable double bond, for example, Nitrostyrene etc. are mentioned.

(7) Monomer having 6 to 18 carbon atoms having an epoxy group and a polymerizable double bond (8) Monomer having 2 to 16 carbon atoms having a halogen element and a polymerizable double bond (9) Polymerization Ester having 4 to 16 carbon atoms having a polymerizable double bond Examples of the ester having 4 to 16 carbon atoms having a polymerizable double bond include vinyl acetate; vinyl propionate; vinyl butyrate; diallyl phthalate; diallyl adipate; Isopropenyl acetate; vinyl methacrylate; methyl-4-vinyl benzoate; cyclohexyl methacrylate; benzyl methacrylate; phenyl (meth) acrylate; vinyl methoxyacetate; vinyl benzoate; ethyl-α-ethoxy acrylate; Alkyl (meth) acrylate [for example, methyl Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc.]; dialkyl fumarate (two alkyl groups have 2 to 8 carbon atoms) A linear alkyl group, a branched alkyl group or an alicyclic alkyl group); a dialkyl maleate (two alkyl groups are a linear alkyl group having 2 to 8 carbon atoms, a branched alkyl group or an alicyclic ring) Poly (meth) allyloxyalkanes (eg, diaryloxyethane, triaryloxyethane, tetraallyloxyethane, tetraallyloxypropane, tetraallyloxybutane or tetrametaallyloxyethane) ); A monomer having a polyalkylene glycol chain and a polymerizable double bond [for example, Polyethylene glycol (Mn = 300) mono (meth) acrylate, polypropylene glycol (Mn = 500) mono (meth) acrylate, methyl alcohol ethylene oxide (hereinafter “ethylene oxide” is abbreviated as “EO”) 10 mol adduct (meta ) Acrylate or lauryl alcohol EO 30 mole adduct (meth) acrylate, etc.]; poly (meth) acrylates {eg poly (meth) acrylates of polyhydric alcohols [eg ethylene glycol di (meth) acrylate, propylene glycol di ( Meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate or polyethylene glycol di (meth) acrylate]] and the like. In the present specification, “(meth) arylo” means alilo and / or metallo.

  Specific examples of the vinyl resin include, for example, a styrene- (meth) acrylic acid ester copolymer, a styrene-butadiene copolymer, a (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a styrene-acrylonitrile copolymer. Copolymers, styrene- (maleic anhydride) copolymers, styrene- (meth) acrylic acid copolymers, styrene- (meth) acrylic acid-divinylbenzene copolymers, and styrene-styrenesulfonic acid- (meth) acrylic acid esters A copolymer etc. are mentioned.

  The vinyl resin may be a homopolymer or copolymer of a monomer having a polymerizable double bond as described in (1) to (9) above, or may be polymerized as described in (1) to (9) above. A polymer obtained by polymerizing a monomer having a double bond and a monomer (m) having a polymerizable double bond having a molecular chain (k) may be used. Examples of the molecular chain (k) include a linear or branched hydrocarbon chain having 12 to 27 carbon atoms, a fluoroalkyl chain having 4 to 20 carbon atoms, and a polydimethylsiloxane chain. The difference in SP value between the molecular chain (k) in the monomer (m) and the insulating liquid (L) is preferably 2 or less. In the present specification, the “SP value” is a method by Fedors [Polym. Eng. Sci. 14 (2) 152, (1974)].

  Although it does not specifically limit as a monomer (m) which has a polymerizable double bond which has a molecular chain (k), For example, the following monomers (m1)-(m3) etc. are mentioned. As the monomer (m), two or more monomers (m1) to (m3) may be used in combination.

Monomer (m1) having a linear hydrocarbon chain having 12 to 27 carbon atoms (preferably 16 to 25 carbon atoms) and a polymerizable double bond
Examples of such a monomer (m1) include mono-linear alkyl of unsaturated monocarboxylic acid (alkyl having 12 to 27 carbon atoms) ester and mono-linear alkyl of unsaturated dicarboxylic acid (alkyl Examples thereof include esters having 12 to 27 carbon atoms. Examples of the unsaturated monocarboxylic acid and unsaturated dicarboxylic acid include (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, and other carboxyl group-containing vinyl monomers having 3 to 24 carbon atoms. Examples include masses.

  Specific examples of the monomer (m1) include, for example, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate and ( (E.g., meta) eicosyl acrylate.

Monomer (m2) having a branched hydrocarbon chain having 12 to 27 carbon atoms (preferably 16 to 25 carbon atoms) and a polymerizable double bond
Examples of such a monomer (m2) include a branched alkyl of an unsaturated monocarboxylic acid (alkyl having 12 to 27 carbon atoms) and a monobranched alkyl of an unsaturated dicarboxylic acid (the carbon number of alkyl is 12-27) Ester etc. are mentioned. As said unsaturated monocarboxylic acid and unsaturated dicarboxylic acid, the thing similar to what was enumerated as a specific example of unsaturated monocarboxylic acid and unsaturated dicarboxylic acid in a monomer (m1) is mentioned, for example.

  Specific examples of the monomer (m2) include, for example, 2-decyltetradecyl (meth) acrylate.

  Other examples include a monomer (m3) having a fluoroalkyl chain having 4 to 20 carbon atoms and a polymerizable double bond.

<Melting point>
Melting | fusing point of shell resin (a) becomes like this. Preferably it is 0-220 degreeC, More preferably, it is 30-200 degreeC, More preferably, it is 40-80 degreeC. From the viewpoints of particle size distribution and shape of the toner particles, powder flowability of the liquid developer (X), heat-resistant storage stability and stress resistance, the melting point of the shell resin (a) is the same as that of the liquid developer (X). It is preferable that it is more than the temperature at the time of manufacture. If the melting point of the shell resin is lower than the temperature at which the liquid developer is produced, it may be difficult to prevent the toner particles from uniting with each other, and it may be difficult to prevent the toner particles from splitting. . In addition, the distribution width in the particle size distribution of the toner particles is difficult to be narrowed. In other words, there is a possibility that the variation in the particle size of the toner particles becomes large.

  In the present specification, the melting point is measured in accordance with a method prescribed in ASTM D3418-82 using a differential scanning calorimeter (such as “DSC20” or “SSC / 580” manufactured by Seiko Instruments Inc.). It is a thing.

<Mn (number average molecular weight)>
The Mn (obtained by GPC measurement) of the shell resin (a) is preferably 100 to 5000000, preferably 200 to 5000000, and more preferably 500 to 500000.

<SP value>
The SP value of the shell resin (a) is preferably 7 to 18 (cal / cm ³ ) ^1/2 , more preferably 8 to 14 (cal / cm ³ ) ^1/2 .

<Shell particles (A)>
Shell particles (A) in the present embodiment include shell resin (a). Any known method can be adopted as the method for producing the shell particles (A), and the method is not particularly limited. For example, the following methods [1] to [7] can be mentioned [1]: Shell resin (a) is pulverized dry using a known dry pulverizer such as a jet mill [2]. : Disperse the powder of shell resin (a) in an organic solvent and pulverize it wet using a known wet disperser such as a bead mill or roll mill [3]: Solution of shell resin (a) using a spray dryer or the like [4]: Addition or cooling of a poor solvent to the shell resin (a) solution to supersaturate and precipitate the shell resin (a) [5]: Shell resin (a) [6]: The precursor of the shell resin (a) is polymerized in water by an emulsion polymerization method, a soap-free emulsion polymerization method, a seed polymerization method, or a suspension polymerization method. [7]: Shi Le precursor of the resin (a) is polymerized by such dispersion polymerization in organic solvents.

  Of these methods, the methods [4], [6] and [7] are preferable from the viewpoint of ease of production of the shell particles (A), and more preferably the methods [6] and [7]. Is preferred.

<Volume average particle diameter>
In this case, the volume average particle diameter of the shell particles (A) can be appropriately adjusted so as to be a particle diameter suitable for obtaining toner particles (C) having a desired particle diameter. The volume average particle diameter of the shell particles (A) is preferably 0.0005 to 3 μm. The upper limit of the volume average particle diameter of the shell particles (A) is more preferably 2 μm, and even more preferably 1 μm. The lower limit of the volume average particle diameter of the shell particles (A) is more preferably 0.01 μm, still more preferably 0.02 μm, and most preferably 0.04 μm. For example, when it is desired to obtain toner particles (C) having a volume average particle diameter of 1 μm, the volume average particle diameter of the shell particles (A) is preferably 0.0005 to 0.3 μm, more preferably 0.001. ~ 0.2 μm. For example, when it is desired to obtain toner particles (C) having a volume average particle size of 10 μm, the volume average particle size of the shell particles (A) is preferably 0.005 to 3 μm, more preferably 0.05 to 2 μm. It is.

<Core resin (b) and core particle (B)>
As described above, in the present embodiment, when the toner particles (C) are core / shell type toner particles, the core resin (b) is the first polyester resin or the second polyester resin. And core particle (B) contains core resin (b).

<SP value>
The SP value of the core resin (b) may be adjusted as appropriate. The SP value of the core resin (b) is preferably 8 to 16 (cal / cm ³ ) ^1/2 , more preferably 9 to 14 (cal / cm ³ ) ^1/2 .

<Melting Point and Glass Transition Temperature (hereinafter abbreviated as “Tg”)>
The melting point and Tg of the core resin (b) may be appropriately adjusted within a preferable range. The melting point of the core resin (b) is preferably 20 to 80 ° C., and the softening start temperature is preferably 40 ° C. or more and 80 ° C. or less from the viewpoint of low temperature fixability.

  In the present specification, Tg may be measured by a differential scanning calorimetry (DSC) method or may be measured using a flow tester. When measuring Tg by the DSC method, for example, using a differential scanning calorimeter (such as “DSC20” or “SSC / 580” manufactured by Seiko Instruments Inc.), the method specified in ASTM D3418-82 is used. It is preferable to measure Tg in conformity.

When Tg is measured using a flow tester, it is preferable to use a Koka type flow tester (for example, “CFT500 type” manufactured by Shimadzu Corporation). An example of Tg measurement conditions in this case is shown below: 30 kg / cm ²
Temperature increase rate: 3.0 ° C / min
Die diameter: 0.50mm
Die length: 10.0 mm.

<Core shell structure>
As described above, the resin contained in the toner particles of the present embodiment is such that the shell particles (A) containing the shell resin (a) are attached or coated on the surfaces of the core particles (B) containing the core resin (b). It is preferable to have a core-shell structure.

  The mass ratio [(A) :( B)] of the shell particles (A) and the core particles (B) is preferably 1:99 to 70:30. From the viewpoint of the uniformity of the particle diameter of the toner particles (C) and the heat resistance stability of the liquid developer (X), the ratio [(A) :( B)] is more preferably 2:98 to 50:50. More preferably, it is 3: 97-35: 65. If the content (mass ratio) of the shell particles (A) is too low, the blocking resistance of the toner particles may be lowered. If the content (mass ratio) of the core particles is too high, the particle size uniformity of the toner particles may decrease.

  From the viewpoint of the particle size distribution of the toner particles (C) and the heat stability of the liquid developer (X), the core-shell structure of the toner particles (C) is 1 to 70 masses relative to the mass of the toner particles (C). % (More preferably 5 to 50% by mass, more preferably 10 to 35% by mass) of shell particles (A) and 30 to 99% by mass (more preferably 50 to 95% by mass, still more preferably 65 to 90% by mass). %) Core particles (B).

  From the viewpoint of the fixing property of the toner particles (C) and the heat stability of the liquid developer (X), the content of the toner particles (C) in the liquid developer (X) is preferably 10 to 50% by mass. More preferably, it is 15-45 mass%, More preferably, it is 20-40 mass%.

<Additives>
The toner particles (C) in the present embodiment preferably contain a colorant in at least one of the shell particles (A) and the core particles (B), and additives other than the colorant (for example, a pigment dispersant, A wax, a charge control agent, a filler, an antistatic agent, a mold release agent, an ultraviolet absorber, an antioxidant, an antiblocking agent, a heat stabilizer, a flame retardant, and the like.

<Colorant>
The colorant contained in the toner particles of the present embodiment is dispersed in the resin (shell particles (A) and / or core particles (B)). The volume average particle size of such a colorant is preferably 0.3 μm or less. If the volume average particle size of the colorant exceeds 0.3 μm, dispersion may be deteriorated, resulting in a decrease in glossiness and the inability to achieve a desired color.

  As such a colorant, conventionally known pigments and the like can be used without any particular limitation, but from the viewpoint of cost, light resistance, colorability, and the like, for example, the following pigments are preferably used. In terms of color composition, these pigments are usually classified as black pigments, yellow pigments, magenta pigments, and cyan pigments. Basically, colors other than black (color images) are subtractive color mixtures of yellow pigments, magenta pigments, and cyan pigments. Is toned.

  Examples of the pigment (black pigment) contained in the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, carbon black derived from biomass, and magnetite, Magnetic powder such as ferrite is also used.

  The black colorant of the present embodiment contains nigrosine. Nigrosine is a mixture of various azine compounds that can be obtained by oxidation-reduction condensation of aniline, aniline hydrochloride and nitrobenzene in the presence of a catalyst such as iron chloride, and its main component is phenazine, phenazine azine. , An azine-based compound that becomes a purple-black dye having skeleton of triphenazine oxazine or the like. Nigrosine may be used alone or in combination with a pigment such as carbon black.

  Such nigrosine is C.I. I. Solvent Black 7 or C.I. I. It is preferably selected from solvent black 5 and the like.

  C. I. Specific examples of Solvent Black 7 include Spirit Black SB, Spirit Black SSBB, Spirit Black AB, Spirit Black ABL, Nubian Black NH- 805, Nubian Black (NUBIAN BLACK) NH-815 and the like are commercially available (both manufactured by Orient Chemical Industry Co., Ltd.).

  In addition, C.I. I. Specific examples of Solvent Black 5 include Nigrosine Base SA, Nigrosine Base SAP, Nigrosine Base SAPL, Nigrosine Base EE, Nigrosine Base EEL, Nigrosine Nigrosine Base EX, Nigrosine Base EXBP, Special Black EB, Nubian Black TN-870, Nubian Black TN-877, Nubian Black BLACK) TN-807, Nubian Black TH-827, Nubian Gray (NUBIAN GRAY) IR-B and other commercial products (all manufactured by Orient Chemical Co., Ltd.) Can do.

  Other than these, Bontron N-01, Bontron N-04, Bontron N-07, Bontron N-09, Bontron N-21, Bontron ) N-71, BONTRON N-75, and BONTRON N-79 are commercially available (all manufactured by Orient Chemical Co., Ltd.).

  Examples of the pigment (magenta pigment) contained in the magenta colorant include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment (yellow pigment) contained in the yellow colorant include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of the pigment (cyan pigment) contained in the cyan colorant include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  These colorants can be used alone or in combination of two or more as required.

<Pigment dispersant>
The pigment dispersant has a function of uniformly dispersing the colorant (pigment) in the toner particles, and it is preferable to use a basic dispersant. Here, the basic dispersant is defined as follows. That is, 0.5 g of pigment dispersant and 20 ml of distilled water are placed in a glass screw tube, shaken for 30 minutes using a paint shaker, and then filtered, and the pH of the filtrate obtained is filtered with a pH meter (product) Name: “D-51” (manufactured by HORIBA, Ltd.) and the case where the pH is higher than 7 is defined as a basic dispersant. In addition, when the pH is smaller than 7, it shall call an acidic dispersing agent.

  The kind of such basic dispersant is not particularly limited. For example, an amine group, amino group, amide group, pyrrolidone group, imine group, imino group, urethane group, quaternary ammonium group, ammonium group, pyridino group, pyridium group, imidazolino group, and imidazolium group in the molecule of the dispersant And compounds having a functional group such as (dispersing agent). The dispersant usually corresponds to a so-called surfactant having a hydrophilic part and a hydrophobic part in the molecule, but as long as it has an action of dispersing a colorant (pigment) as described above, Compounds can be used.

  Commercially available products of such basic dispersants include, for example, “Ajisper PB-821” (trade name), “Azisper PB-822” (trade name), “Azisper PB-881” (product) manufactured by Ajinomoto Fine Techno Co., Ltd. Name) or “Solspers 28000” (product name), “Solspurs 32000” (product name), “Solspurs 32500” (product name), “Solspurs 35100” (product name), “Solspurs 37500” (product name) Product name).

  Further, it is more preferable to select a pigment dispersant that does not dissolve in the insulating liquid (carrier liquid). For that reason, “Ajisper PB-821” (trade name), “Ajisper PB-822” (trade name), and “Ajisper PB-881” (trade name) manufactured by Ajinomoto Fine Techno Co. are more preferred. Although the detailed mechanism is unknown, the use of such a pigment dispersant makes it easy to obtain a desired shape.

  The pigment dispersant is preferably added in an amount of 1 to 100% by mass with respect to the colorant (pigment). More preferably, it is 1-40 mass%. If it is less than 1% by mass, the dispersibility of the colorant (pigment) may be insufficient, the required ID (image density) may not be achieved, and the fixing strength may be reduced. On the other hand, if the amount exceeds 100% by mass, a dispersant more than the amount necessary for pigment dispersion is added, and the excess dispersant may be dissolved in the insulating liquid, which increases the chargeability and fixing strength of the toner particles. May have adverse effects.

  Such pigment dispersants can be used singly or in combination of two or more.

<Insulating liquid>
The insulating liquid contained in the liquid developer of the present embodiment may have a resistance value (approximately 10 ¹¹ to 10 ¹⁶ Ω · cm) that does not disturb the electrostatic latent image. Furthermore, a solvent having low odor and toxicity is preferred. In general, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes and the like can be mentioned. In particular, a normal paraffin solvent and an isoparaffin solvent are preferable in terms of odor, harmlessness, and cost. Specifically, Moresco White (trade name, manufactured by Matsumura Oil Research Co., Ltd.), Isopar (trade name, manufactured by ExxonMobil), Shellsol (trade name, manufactured by Shell Chemicals Japan Co., Ltd.), IP Solvent 1620, IP solvent 2028, IP solvent 2835 (both are trade names, manufactured by Idemitsu Kosan Co., Ltd.), and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Production Example 1> [Production of polyester resin]
In a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, a cooling tube and a nitrogen introduction tube, 286 parts by mass of dodecanedioic acid, 190 parts by mass of 1,6-hexanediol and titanium dihydroxybis (triethanol as a condensation catalyst) Aminate) 1 part by mass was added and reacted at 180 ° C. under a nitrogen stream for 8 hours while distilling off the generated water. Next, while the temperature was gradually raised to 220 ° C., the reaction was performed for 4 hours while distilling off the generated water under a nitrogen stream. Furthermore, it was made to react under the reduced pressure of 0.007-0.026 MPa for 1 hour. Thereby, a polyester resin was obtained. About the obtained polyester resin, melting | fusing point was 68 degreeC, Mn was 4900, and Mw was 10,000.

In addition, the above-mentioned method was employ | adopted for the measurement of melting | fusing point, Mn, and Mw (it is the same below).
<Production Example 2> [Production of dispersion (W1) of shell particles (A1)]
In a beaker made of glass, 80 parts by mass of 2-decyltetradecyl methacrylate, 5 parts by mass of methyl methacrylate, 5 parts by mass of methacrylic acid, an isocyanate group-containing monomer (trade name: “Karenz MOI”, manufactured by Showa Denko KK) 20 parts by mass of an equimolar reaction product with the polyester resin obtained in Production Example 1 and 0.5 parts by mass of azobismethoxydimethylvaleronitrile were added and mixed by stirring at 20 ° C. Thereby, a monomer solution was obtained.

  Next, a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, a dropping funnel, a solvent removal device, and a nitrogen introduction tube was prepared. 195 parts by mass of THF was put into the reaction vessel, and the monomer solution was put into a dropping funnel provided in the reaction vessel. After the gas phase portion of the reaction vessel was replaced with nitrogen, the monomer solution was added dropwise to THF in the reaction vessel over 1 hour at 70 ° C. in a sealed state. Three hours after the completion of the dropwise addition of the monomer solution, a mixture of 0.05 parts by mass of azobismethoxydimethylvaleronitrile and 5 parts by mass of THF was placed in a reaction vessel, reacted at 70 ° C. for 3 hours, and then cooled to room temperature. . Thereby, a copolymer solution was obtained.

  Next, 400 parts by mass of the obtained copolymer solution was added dropwise to 600 parts by mass of IP solvent 2028 (made by Idemitsu Kosan Co., Ltd.) with stirring, and then THF was distilled off at 40 ° C. under a reduced pressure of 0.039 MPa. Thereby, a dispersion liquid (W1) of shell particles (A1) was obtained. The volume average particle diameter of the shell particles (A1) in the dispersion (W1) was 0.13 μm.

<Production Example 3> [Production of Core Resin (b1) Formation Solution (Y1)]
964 masses of polyester resin (Mn: 5000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  36 parts by mass of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b1) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b1) measured by the above-described method was 25000.

  Next, 1000 parts by mass of the core resin (b1) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b1) in acetone. As a result, a solution (Y1) for forming the core resin (b1) was obtained. At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Production Example 4> [Production of core resin (b2) forming solution (Y2)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 962 parts by mass of polyester resin (Mn: 5000) obtained from sebacic acid and 1,6-hexanediol (molar ratio 1: 1) and 1300 parts by mass of acetone Part was added and stirred to dissolve uniformly.

  To this solution, 38 parts by mass of IPDI was added and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b2) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b2) measured by the above-described method was 40000.

  Next, 1000 parts by mass of the core resin (b2) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b2) in acetone. As a result, a solution (Y2) for forming the core resin (b2) was obtained. At this time, it was 45 mass% when solid content concentration of this solution was measured.

<Production Example 5> [Production of core resin (b3) forming solution (Y3)]
957 masses of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  43 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b3) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b3) measured by the above-mentioned method was 17000.

  Next, 1000 parts by mass of the core resin (b3) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b3) in acetone. Thereby, a solution (Y3) for forming the core resin (b3) was obtained. At this time, it was 41 mass% when solid content concentration of this solution was measured.

<Production Example 6> [Production of core resin (b4) forming solution (Y4)]
955 mass of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  45 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b4) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b4) measured by the above-described method was 22000.

  Next, 1000 parts by mass of the core resin (b4) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b4) in acetone. Thereby, a solution (Y4) for forming the core resin (b4) was obtained. At this time, it was 45 mass% when solid content concentration of this solution was measured.

<Production Example 7> [Production of core resin (b5) forming solution (Y5)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 949 parts by mass of a polyester resin (Mn: 3500) obtained from sebacic acid and 1,6 hexanediol (molar ratio 1: 1) and 1300 parts by mass of acetone And stirred to dissolve uniformly.

  To this solution, 51 parts by mass of IPDI was added and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b5) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b5) measured by the above-described method was 20000.

  Next, 1000 parts by mass of the core resin (b5) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b5) in acetone. Thereby, a core resin (b5) forming solution (Y5) was obtained. At this time, it was 42 mass% when solid content concentration of this solution was measured.

<Production Example 8> [Production of core resin (b6) forming solution (Y6)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 953 parts by mass of polyester resin (Mn: 4000) obtained from sebacic acid and 1,6 hexanediol (molar ratio 1: 1) and 1300 parts by mass of acetone And stirred to dissolve uniformly.

  47 parts by mass of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b6) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b6) measured by the above-mentioned method was 34000.

  Next, 1000 parts by mass of the core resin (b6) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b6) in acetone. As a result, a solution (Y6) for forming the core resin (b6) was obtained. At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Production Example 9> [Production of core resin (b7) forming solution (Y7)]
919 masses of polyester resin (Mn: 2000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  82 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b7) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b7) measured by the above-described method was 8000.

  Next, 1000 parts by mass of the core resin (b7) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b7) in acetone. This obtained core resin (b7) formation solution (Y7). At this time, it was 46 mass% when solid content concentration of this solution was measured.

<Production Example 10> [Production of Core Resin (b8) Formation Solution (Y8)]
957 masses of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  43 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b8) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b8) measured by the above-described method was 18000.

  Next, 1000 parts by mass of the core resin (b8) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b8) in acetone. Thereby, a solution (Y8) for forming the core resin (b8) was obtained. At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Production Example 11> [Production of Core Resin (b9) Formation Solution (Y9)]
959 masses of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  41 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b9) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b9) measured by the above-described method was 14000.

  Next, 1000 parts by mass of the core resin (b9) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b9) in acetone. This obtained core resin (b9) formation solution (Y9). At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Production Example 12> [Production of Core Resin (b10) Formation Solution (Y10)]
954 mass of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  46 parts by mass of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b10) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b10) measured by the above-described method was 25000.

  Next, 1000 parts by mass of the core resin (b10) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b10) in acetone. This obtained core resin (b10) formation solution (Y10). At this time, it was 42 mass% when solid content concentration of this solution was measured.

<Production Example 13> [Production of Core Resin (b11) Formation Solution (Y11)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 951 parts by mass of a polyester resin (Mn: 3500) obtained from sebacic acid and 1,6 hexanediol (molar ratio 1: 1) and 1300 parts by mass of acetone And stirred to dissolve uniformly.

  To this solution, 50 parts by mass of IPDI was added and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b11) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b11) measured by the above-described method was 16000.

  Next, 1000 parts by mass of the core resin (b11) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b11) in acetone. This obtained core resin (b11) formation solution (Y11). At this time, it was 45 mass% when solid content concentration of this solution was measured.

<Production Example 14> [Production of Core Resin (b12) Formation Solution (Y12)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 952 parts by mass of a polyester resin (Mn: 4000) obtained from sebacic acid and 1,6 hexanediol (molar ratio 1: 1) and 1300 parts by mass of acetone And stirred to dissolve uniformly.

  48 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b12) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b12) measured by the above-mentioned method was 37000.

  Next, 1000 parts by mass of the core resin (b12) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b12) in acetone. This obtained core resin (b12) formation solution (Y12). At this time, it was 42 mass% when solid content concentration of this solution was measured.

<Production Example 15> [Production of Core Resin (b13) Formation Solution (Y13)]
927 masses of polyester resin (Mn: 2000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  To this solution, 74 parts by mass of IPDI was added and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b13) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b13) measured by the above-described method was 5000.

  Next, 1000 parts by mass of the core resin (b13) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b13) in acetone. Thereby, a solution (Y13) for forming the core resin (b13) was obtained. At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Production Example 16> [Production of core resin (b14) forming solution (Y14)]
955 mass of polyester resin (Mn: 4000) obtained from sebacic acid, adipic acid and ethylene glycol (molar ratio 0.8: 0.2: 1) in a reaction vessel equipped with a stirrer, heating / cooling device and thermometer And 1300 parts by mass of acetone were added and stirred to dissolve uniformly.

  42 parts by weight of IPDI was added to this solution and reacted at 80 ° C. for 6 hours. When the NCO value became 0, 28 parts by mass of phthalic anhydride was added and reacted at 180 ° C. for 1 hour to obtain a core resin (b14) which is a urethane-modified polyester resin. At this time, Mn of the core resin (b14) measured by the above-described method was 21000.

  Next, 1000 parts by mass of the core resin (b14) and 1000 parts by mass of acetone were placed in a beaker and stirred to uniformly dissolve the core resin (b14) in acetone. This obtained core resin (b14) formation solution (Y14). At this time, it was 44 mass% when solid content concentration of this solution was measured.

<Measurement of heat of fusion>
The heat of fusion (H1) at the first temperature rise and the heat of fusion (H2) at the second temperature rise by differential scanning calorimetry of the core resin (b1) to the core resin (b14) obtained as described above. Measurement was performed according to the method described above. A differential scanning calorimeter (product name: “DSC210”, manufactured by Seiko Instruments Inc.) was used as a measuring device. The measurement results of H1 and H2 and the calculation result of H2 / H1 are shown in Table 1 together with the structure of each resin.

<Production Example 17> [Production of Cyan Colorant Dispersion (P1)]
In a beaker, 20 parts by mass of acid-treated copper phthalocyanine (trade name: “Fastogen Blue FDB-14”, manufactured by DIC) as a cyan colorant, a pigment dispersant (trade name: “Azisper PB-821”, Ajinomoto Fine Techno ( Co., Ltd.) and 5 parts by mass of acetone and 75 parts by mass of acetone were added, stirred and uniformly dispersed, and then copper phthalocyanine was finely dispersed by a bead mill to obtain a cyan colorant dispersion (P1). The volume average particle diameter of copper phthalocyanine in the cyan colorant dispersion (P1) was 0.2 μm.

<Production Example 18> [Production of black colorant dispersion (P2)]
In a beaker, 13 parts by mass of carbon black (trade name: “Mogal L”, manufactured by Cabot) as a black colorant, 5 parts by mass of acid-treated copper phthalocyanine (trade name: “Fastogen Blue FDB-14”, manufactured by DIC) , 2 parts by mass of nigrosine (trade name: “TH-827”, manufactured by Orient Chemical Co., Ltd.), 5 parts by mass of a pigment dispersant (trade name: “Azisper PB-821”, manufactured by Ajinomoto Fine Techno Co., Ltd.), and acetone 75 After adding a part by mass and stirring to uniformly disperse, copper phthalocyanine was finely dispersed by a bead mill to obtain a black colorant dispersion (P2). The volume average particle diameter of copper phthalocyanine in the black colorant dispersion (P2) was 0.2 μm.

<Production Example 19> [Production of black colorant dispersion (P3)]
In a beaker, 9 parts by mass of carbon black (trade name: “Mogal L”, manufactured by Cabot Corporation) as a black colorant, acid-treated copper phthalocyanine (trade name: “Fastogen Blue FDB-14”, manufactured by DIC Corporation) 6.3 Parts by mass, nigrosine (trade name: “TH-827”, manufactured by Orient Chemical Co., Ltd.), 4.7 parts by weight, pigment dispersant (trade name: “Azisper PB-821”, manufactured by Ajinomoto Fine Techno Co., Ltd.), 5 mass And 75 parts by mass of acetone were added and stirred to uniformly disperse, and then copper phthalocyanine was finely dispersed by a bead mill to obtain a black colorant dispersion (P3). The volume average particle diameter of copper phthalocyanine in the black colorant dispersion (P3) was 0.2 μm.

<Production Example 20> [Production of black colorant dispersion (P4)]
In a beaker, 5 parts by mass of carbon black (trade name: “Mogal L”, manufactured by Cabot Corporation) as a black colorant, acid-treated copper phthalocyanine (trade name: “Fastogen Blue FDB-14”, manufactured by DIC Corporation) 4.9 Parts by mass, nigrosine (trade name: “TH-827”, manufactured by Orient Chemical Co., Ltd.) 10.1 parts by mass, pigment dispersant (trade name: “Azisper PB-821”, manufactured by Ajinomoto Fine Techno Co., Ltd.) 5 mass And 75 parts by mass of acetone were added and stirred to uniformly disperse, and then copper phthalocyanine was finely dispersed by a bead mill to obtain a black colorant dispersion (P4). The volume average particle diameter of copper phthalocyanine in the black colorant dispersion (P4) was 0.2 μm.

<Production Example 21> [Production of cyan developer (Z-1)]
Into a beaker, 40 parts by mass of the core resin (b1) forming solution (Y1) and 20 parts by mass of the cyan colorant dispersion (P1) were added, and a TK auto homomixer (manufactured by Primix Co., Ltd.) was used at 25 ° C. The mixture was stirred at 8000 rpm and dispersed uniformly to obtain a resin solution (Y1P1).

  In another beaker, 67 parts by mass of an insulating liquid (trade name: “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.) and 12 parts by mass of the dispersion liquid (W1) of shell particles (A1) were charged and uniformly dispersed. Next, while stirring at 10000 rpm using a TK auto homomixer at 25 ° C., 60 parts by mass of the resin solution (Y1P1) was added and stirred for 2 minutes. Next, this mixed solution was put into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removal device. Acetone was distilled off from the resin solution (Y1P1) until the content became 5% by mass or less.

  As a result, a cyan developer (Z-1) having a mass ratio of copper phthalocyanine to the total solid content contained in the liquid developer of 0.16 was obtained. In the cyan developer (Z-1), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B1) made of the core resin (b1). (C-1) was formed.

  The breakdown of the solid content of the cyan developer (Z-1) (the mass ratio of each component when the total solid content is 1; the same applies hereinafter) is the core particle (B1): 0.707, shell. Particles (A1): 0.092, copper phthalocyanine: 0.161, pigment dispersant: 0.040.

<Production Example 22> [Production of cyan developer (Z-2)]
Into a beaker, 40 parts by mass of the core resin (b2) forming solution (Y2) and 20 parts by mass of the cyan colorant dispersion (P1) were added, and a TK auto homomixer (manufactured by Primics Co., Ltd.) was used at 25 ° C. The mixture was stirred at 8000 rpm and uniformly dispersed to obtain a resin solution (Y2P1).

  In another beaker, 67 parts by mass of an insulating liquid (trade name: “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.) and 12 parts by mass of the dispersion liquid (W1) of shell particles (A1) were charged and uniformly dispersed. Next, while stirring at 10000 rpm using a TK auto homomixer at 25 ° C., 60 parts by mass of the resin solution (Y2P1) was added and stirred for 2 minutes. Next, this mixed solution was put into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removal device. After the temperature was raised to 35 ° C., the acetone concentration was reduced to 0.039 MPa at a reduced pressure of 0.039 MPa. Acetone was distilled off from the resin solution (Y2P1) until it became 5 mass% or less.

  As a result, a cyan developer (Z-2) having a mass ratio of copper phthalocyanine to the total solid content contained in the liquid developer of 0.16 was obtained. In the cyan developer (Z-2), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B2) made of the core resin (b2). (C-2) was formed.

  The breakdown of the solid content of the cyan developer (Z-2) is as follows: core particle (B2): 0.707, shell particle (A1): 0.092, copper phthalocyanine: 0.161, pigment dispersant: 0.8. 040.

<Production Example 23> [Production of Black Developer (Z-3)]
Into a beaker, 40 parts by mass of the core resin (b3) forming solution (Y3) and 45 parts by mass of the black colorant dispersion (P2) were added, and a TK auto homomixer (manufactured by Primix Co., Ltd.) was used at 25 ° C. The mixture was stirred at 8000 rpm and uniformly dispersed to obtain a resin solution (Y3P2).

  In another beaker, 67 parts by mass of an insulating liquid (trade name: “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.) and 13 parts by mass of the dispersion liquid (W1) of shell particles (A1) were charged and uniformly dispersed. Next, while stirring at 10000 rpm using a TK auto homomixer at 25 ° C., 60 parts by mass of the resin solution (Y3P2) was added and stirred for 2 minutes. Next, this mixed solution was put into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removal device. Acetone was distilled off from the resin solution (Y3P2) until the content became 5% by mass or less.

  As a result, a black developer (Z-3) in which the mass ratio of the black colorant to the total solid content contained in the liquid developer was 0.30 and the mass ratio of nigrosine was 0.03 was obtained. In addition, in the black developer (Z-3), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B3) made of the core resin (b3). (C-3) was formed.

  The breakdown of the solid content of the black developer (Z-3) is as follows: core particle (B3): 0.544, shell particle (A1): 0.082, carbon black: 0.194, copper phthalocyanine: 0.075. Nigrosine: 0.03, pigment dispersant: 0.075.

<Production Example 24> [Production of Black Developer (Z-4)]
In Production Example 23, except that the core resin (b3) forming solution (Y3) is changed to the core resin (b4) forming solution (Y4) to obtain a resin solution (Y4P2), the same as in Production Example 23, A black developer (Z-4) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.03 was obtained. In addition, in the black developer (Z-4), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B4) made of the core resin (b4). (C-4) was formed.

  The breakdown of the solid content of the black developer (Z-4) is as follows: core particle (B4): 0.544, shell particle (A1): 0.082, carbon black: 0.194, copper phthalocyanine: 0.075. Nigrosine: 0.03, pigment dispersant: 0.075.

<Production Example 25> [Production of Black Developer (Z-5)]
Into a beaker, 40 parts by mass of the core resin (b5) forming solution (Y5) and 45 parts by mass of the black colorant dispersion (P3) were added, and a TK auto homomixer (manufactured by Primix Co., Ltd.) was used at 25 ° C. The mixture was stirred at 8000 rpm and uniformly dispersed to obtain a resin solution (Y5P3).

  In another beaker, 67 parts by mass of an insulating liquid (trade name: “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.) and 13 parts by mass of the dispersion liquid (W1) of shell particles (A1) were charged and uniformly dispersed. Next, while stirring at 10000 rpm using a TK auto homomixer at 25 ° C., 60 parts by mass of the resin solution (Y5P3) was added and stirred for 2 minutes. Next, this mixed solution was put into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removal device. Acetone was distilled off from the resin solution (Y5P3) until the content became 5% by mass or less.

  As a result, a black developer (Z-5) in which the mass ratio of the black colorant to the total solid content contained in the liquid developer was 0.30 and the mass ratio of nigrosine was 0.07 was obtained. In the black developer (Z-5), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B5) made of the core resin (b5). (C-5) was formed.

  The breakdown of the solid content of the black developer (Z-5) is as follows: core particle (B5): 0.544, shell particle (A1): 0.082, carbon black: 0.134, copper phthalocyanine: 0.094. Nigrosine: 0.07, Pigment dispersant: 0.075.

<Production Example 26> [Production of Black Developer (Z-6)]
In Production Example 25, except that the core resin (b5) forming solution (Y5) is changed to the core resin (b6) forming solution (Y6) to obtain a resin solution (Y6P3), the same as in Production Example 25, A black developer (Z-6) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.07 was obtained. In addition, in the black developer (Z-6), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B6) made of the core resin (b6). (C-6) was formed.

  The breakdown of the solid content of the black developer (Z-6) is as follows: core particle (B6): 0.544, shell particle (A1): 0.082, carbon black: 0.134, copper phthalocyanine: 0.094. Nigrosine: 0.07, Pigment dispersant: 0.075.

<Production Example 27> [Production of black developer (Z-7)]
Into a beaker, 40 parts by mass of the core resin (b7) forming solution (Y7) and 45 parts by mass of the black colorant dispersion (P4) were added, and a TK auto homomixer (manufactured by Primix Co., Ltd.) was used at 25 ° C. The mixture was stirred at 8000 rpm and uniformly dispersed to obtain a resin solution (Y7P4).

  Into another beaker, 67 parts by mass of an insulating liquid (trade name: “IP Solvent 2028”, manufactured by Idemitsu Kosan Co., Ltd.) and 14 parts by mass of the dispersion liquid (W1) of shell particles (A1) were charged and uniformly dispersed. Next, while stirring at 10000 rpm using a TK auto homomixer at 25 ° C., 60 parts by mass of the resin solution (Y7P4) was added and stirred for 2 minutes. Next, this mixed solution was put into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removal device. After the temperature was raised to 35 ° C., the acetone concentration was reduced to 0.039 MPa at a reduced pressure of 0.039 MPa. Acetone was distilled off from the resin solution (Y7P4) until the content became 5% by mass or less.

  As a result, a black developer (Z-7) in which the mass ratio of the black colorant to the total solid content contained in the liquid developer was 0.30 and the mass ratio of nigrosine was 0.15 was obtained. In the black developer (Z-7), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B7) made of the core resin (b7). (C-7) was formed.

  The breakdown of the solid content of the black developer (Z-7) is as follows: core particle (B7): 0.541, shell particle (A1): 0.088, carbon black: 0.074, copper phthalocyanine: 0.074. Nigrosine: 0.15, pigment dispersant: 0.074.

<Production Example 28> [Production of black developer (Z-8)]
In Production Example 27, except that the core resin (b7) forming solution (Y7) is changed to the core resin (b8) forming solution (Y8) to obtain a resin solution (Y8P4), the same as in Production Example 27, A black developer (Z-8) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.15 was obtained. In the black developer (Z-8), toner particles having a core / shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B8) made of the core resin (b8). (C-8) was formed.

  The breakdown of the solid content of the black developer (Z-8) is as follows: core particle (B8): 0.541, shell particle (A1): 0.088, carbon black: 0.074, copper phthalocyanine: 0.074. Nigrosine: 0.15, pigment dispersant: 0.074.

<Production Example 29> [Production of Black Developer (Z-9)]
In Production Example 23, except that the core resin (b3) forming solution (Y3) is changed to the core resin (b9) forming solution (Y9) to obtain a resin solution (Y9P2), the same as in Production Example 23, A black developer (Z-9) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.03 was obtained. In addition, in the black developer (Z-9), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B9) made of the core resin (b9). (C-9) was formed.

  The breakdown of the solid content of the black developer (Z-9) is as follows: core particle (B9): 0.544, shell particle (A1): 0.082, carbon black: 0.194, copper phthalocyanine: 0.075. Nigrosine: 0.03, pigment dispersant: 0.075.

<Production Example 30> [Production of Black Developer (Z-10)]
In Production Example 23, except that the core resin (b3) forming solution (Y3) is changed to the core resin (b10) forming solution (Y10) to obtain a resin solution (Y10P2), the same as in Production Example 23, A black developer (Z-10) in which the mass ratio of the black colorant to the total solid content in the liquid developer was 0.30 and the mass ratio of nigrosine was 0.03 was obtained. In addition, in the black developer (Z-10), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B10) made of the core resin (b10). (C-10) was formed.

  The breakdown of the solid content of the black developer (Z-10) is as follows: core particle (B10): 0.544, shell particle (A1): 0.082, carbon black: 0.194, copper phthalocyanine: 0.075. Nigrosine: 0.03, pigment dispersant: 0.075.

<Production Example 31> [Production of Black Developer (Z-11)]
In Production Example 25, except that the core resin (b5) forming solution (Y5) is changed to the core resin (b11) forming solution (Y11) to obtain a resin solution (Y11P3), the same as in Production Example 25, A black developer (Z-11) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.07 was obtained. In the black developer (Z-11), toner particles having a core / shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B11) made of the core resin (b11). (C-11) was formed.

  The breakdown of the solid content of the black developer (Z-11) is as follows: core particle (B11): 0.544, shell particle (A1): 0.082, carbon black: 0.134, copper phthalocyanine: 0.094. Nigrosine: 0.07, Pigment dispersant: 0.075.

<Production Example 32> [Production of Black Developer (Z-12)]
In Production Example 25, except that the core resin (b5) forming solution (Y5) is changed to the core resin (b12) forming solution (Y12) to obtain a resin solution (Y12P3), the same as in Production Example 25, A black developer (Z-12) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.07 was obtained. In addition, in the black developer (Z-12), toner particles having a core / shell structure in which shell particles (A1) are attached to or coated on the surface of the core particles (B12) made of the core resin (b12). (C-12) was formed.

  The breakdown of the solid content of the black developer (Z-12) is as follows: core particle (B12): 0.544, shell particle (A1): 0.082, carbon black: 0.134, copper phthalocyanine: 0.094. Nigrosine: 0.07, Pigment dispersant: 0.075.

<Production Example 33> [Production of Black Developer (Z-13)]
In Production Example 27, except that the core resin (b7) formation solution (Y7) is changed to the core resin (b13) formation solution (Y13) to obtain a resin solution (Y13P4), the same as Production Example 27, A black developer (Z-13) having a mass ratio of the black colorant to the total solid content in the liquid developer of 0.30 and a mass ratio of nigrosine of 0.15 was obtained. In addition, in the black developer (Z-13), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B13) made of the core resin (b13). (C-13) was formed.

  The breakdown of the solid content of the black developer (Z-13) is as follows: core particle (B13): 0.541, shell particle (A1): 0.088, carbon black: 0.074, copper phthalocyanine: 0.074. Nigrosine: 0.15, pigment dispersant: 0.074.

<Production Example 34> [Production of Black Developer (Z-14)]
In Production Example 27, except that the core resin (b7) forming solution (Y7) is changed to the core resin (b14) forming solution (Y14) to obtain a resin solution (Y14P4), the same as in Production Example 27, A black developer (Z-14) having a mass ratio of black colorant to the total solid content of the liquid developer of 0.30 and a mass ratio of nigrosine of 0.15 was obtained. In addition, in the black developer (Z-14), toner particles having a core-shell structure in which shell particles (A1) are attached to or coated on the surfaces of the core particles (B14) made of the core resin (b14). (C-14) was formed.

  The breakdown of the solid content of the black developer (Z-14) is as follows: core particle (B14): 0.541, shell particle (A1): 0.088, carbon black: 0.074, copper phthalocyanine: 0.074. Nigrosine: 0.15, pigment dispersant: 0.074.

<Measurement of median diameter and average circularity>
The median diameter (volume distribution) and average circularity of the toner particles (C-1) to toner particles (C-14) obtained as described above were measured using a flow type particle image analyzer (trade name: “FPIA-3000S”). , Manufactured by Sysmex). The same IP solvent 2028 as the insulating liquid of each liquid developer was used as the flow solvent.

  Suspensions were prepared by adding 50 mg of each liquid developer into 20 g of IP solvent 2028 to which 30 mg of a dispersant (trade name: “S13940”, manufactured by Nippon Lubrizol Co., Ltd.) was added. Dispersion treatment was performed for about 5 minutes using a sonic disperser (trade name: “Ultrasonic Cleaner Model VS-150”, manufactured by Welbo Clear).

  Then, using this suspension, the median diameter (D50), circularity (circumference of circle equal to particle area / periphery of particle) and average circularity of the volume distribution of toner particles were measured. The results are shown in Table 2 together with the constitution of each liquid developer and each toner particle.

<Example 1>
A liquid developer set according to Example 1 was configured using the black developer Z-3 and the cyan developer Z-1 as the chromatic developer.

<Examples 2 to 6 and Comparative Examples 1 to 6>
As shown in Table 3, liquids according to Examples 2 to 6 and Comparative Examples 1 to 6 were prepared by combining the black developer of the production example and the cyan developer (chromatic developer) of the production example. Each developer set was configured. In Table 3, the column of Equation (1) shows in the formula (1) described above, Mc (1-2a ^0.5) of the calculation result and Mc (1-0.5a ^0.5) of the calculation results, respectively.

<Evaluation>
<Image forming apparatus>
FIG. 1 shows a schematic conceptual diagram of an image forming apparatus used for producing an image for evaluation of a liquid developer set. The process conditions and process outline of this apparatus are as follows.

  In this evaluation, an image forming apparatus that performs primary transfer from the photosensitive member to the intermediate transfer member and then secondary transfer to the recording material is shown. However, the same effect can be obtained by the method of transferring directly from the photosensitive member to the recording material. can get.

  FIG. 1 shows a single-color image forming apparatus in order to simplify the explanation and make it easy to understand the explanation, but in actual evaluation, it has a plurality of developing tanks and transfer rollers. A multicolor image forming apparatus that forms a color image by superposing a plurality of developers was used.

  First, the liquid developer 6 is placed in the developing tank 5 of the image forming apparatus 100. The liquid developer 6 is pumped up by the anilox roller 22 and sent to the leveling roller 21. Excess liquid developer 6 on the surface of the anilox roller 22 is scraped off by the anilox regulating blade 23 before reaching the leveling roller 21, and the level of the liquid developer 6 is adjusted so that the liquid developer 6 has an equal layer thickness. The Next, the liquid developer 6 is transferred from the leveling roller 21 to the developer carrier 24.

  The photoreceptor 1 is charged by the charging unit 7 and a latent image is formed by the exposure unit 8. Corresponding to the image on which the latent image is formed, the liquid developer 6 is charged on the toner particles by the development charger 26 and then developed on the photoreceptor 1. The liquid developer 6 that has not transferred to the photoreceptor 1 is scraped off and collected by the cleaning blade 25 downstream of the developing unit.

  The liquid developer 6 developed on the photosensitive member 1 is electrostatically primary transferred to the intermediate transfer member 10 in the primary transfer unit 2. The liquid developer 6 (toner particles) carried on the intermediate transfer body 10 is electrostatically secondary transferred onto the recording material 12 in the secondary transfer unit 3. The liquid developer 6 (toner particles) transferred to the recording material 12 is fixed by a fixing device (not shown) and a printed image is completed.

  The liquid developer 6 that has not been transferred and remains on the photosensitive member 1 is scraped off by the cleaning blade 9 of the image carrier cleaning unit, and the photosensitive member 1 repeats charging, exposing, and developing steps to perform a printing operation. Similarly, the liquid developer 6 that cannot be completely transferred and remains on the intermediate transfer member 10 is scraped off by the cleaning blade 11.

  The toner particles are charged to a positive polarity by the development charger 26. The potential of the intermediate transfer member 10 was −400V, and the potential of the transfer roller 4 was −1200V. The conveyance speed was 400 mm / s.

In this evaluation, coated paper (trade name: “OK Top Coat” (128 g / m ² ), manufactured by Oji Paper Co., Ltd.) was used as the recording material.

<Evaluation of glossiness>
Using the image forming apparatus described above, a solid pattern (10 cm × 10 cm, toner particle adhesion amount: 2 g / m ² ) with cyan developer and black developer, the same adhesion amount, and the same recording material (coated paper) ) And then fixed with a heat roller. The fixing condition is that the nip time is 40 msec. The fixing temperature was set to the temperature shown in the “fixing roll temperature” column of Table 4.

  Thereafter, the glossiness of the cyan solid portion and the black solid portion of the fixed image obtained above was measured with a 75 ° gloss meter (trade name: “VG-2000”, manufactured by Nippon Denshoku Co., Ltd.). The results are shown in Table 4. In Table 4, in the column of “Glossiness”, when the “difference (absolute value)” is 10 or less, the difference in glossiness is small and good.

<Evaluation of fixing strength>
The fixing strength of the cyan solid portion and the black solid portion of the fixed image obtained in the same manner as described above was evaluated by a tape peeling test of the fixed image. In other words, after affixing the tape to the measurement target site on the coated paper after image fixing, the tape is peeled off, and the image density (ID) of the image peeled off the tape is measured by a reflection densitometer (trade name: “X -Rite model 404 "(manufactured by X-Rite), and the following two-stage rank evaluation was performed. The results are shown in Table 4. As the tape, “Scotch Mending Tape” (trade name, manufactured by 3M) was used.
A: Less than image density (ID) of 0.1 B: Image density (ID) of 0.1 or more The smaller the image density value of the peeled image, the higher the fixing strength. Therefore, those in which “Cyan” and “Black” are both “A” have good fixing strength as a liquid developer set. On the other hand, one in which either “Cyan” or “Black” is “B” does not have sufficient fixing strength as a liquid developer set.

As is apparent from Tables 3 and 4, a liquid developer set including a black developer containing first toner particles and a chromatic developer containing second toner particles, the first toner particles being 1 polyester resin, a black colorant and nigrosine, and the second toner particles contain a second polyester resin and a chromatic colorant. The following formula (1): “Mc (1-2a ^0.5 ) <Mk <Mc ( The liquid developer set of Examples satisfying 1-0.5a ^0.5 ) ”has extremely good gloss and fixing strength, and they are highly compatible. That is, it was confirmed that the liquid developer set of the example can fix each liquid developer under the same temperature condition and has the same and high fixing quality.

  On the other hand, the liquid developer set of the comparative example that does not satisfy such conditions does not achieve both glossiness and fixing strength, and does not provide sufficient fixing quality.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Photoconductor, 2 Primary transfer part, 3 Secondary transfer part, 4 Transfer roller, 5 Developing tank, 6 Liquid developer, 7 Charging part, 8 Exposure part, 9 Cleaning blade, 10 Intermediate transfer body, 11 Cleaning blade, 12 recording material, 21 leveling roller, 22 anilox roller, 23 anilox regulating blade, 24 developer carrying member, 25 cleaning blade, 26 developing charger, 100 image forming apparatus.

Claims (7)

A liquid developer set comprising a black developer containing first toner particles and a chromatic developer containing second toner particles,
The first toner particles include a first polyester resin, a black colorant and nigrosine,
The second toner particles include a second polyester resin and a chromatic colorant,
A liquid developer set satisfying the following formula (1).
Mc (1-2a ^0.5 ) <Mk <Mc (1-0.5a ^0.5 ) (1)
(In the formula (1), Mk represents the number average molecular weight of the first polyester resin, Mc represents the number average molecular weight of the second polyester resin, and 10000 ≦ Mc ≦ 50000, and a represents black development of the nigrosine. The mass ratio with respect to the total solid content contained in the agent is 0.01 ≦ a ≦ 0.20.)   The first polyester resin and the second polyester resin include a common structural unit in a molecular structure, and the common structural unit occupies 80% or more of all the structural units in each molecular structure. Item 2. A liquid developer set according to Item 1.   The liquid developer set according to claim 1, wherein the first polyester resin and the second polyester resin are substantially the same polymer species. The said 1st polyester resin and the said 2nd polyester resin are crystalline resins in which the heat of fusion by differential scanning calorimetry respectively satisfy | fills following formula (2) and (3), respectively. Liquid developer set.
5 ≦ H1 ≦ 70 (2)
0.2 ≦ H2 / H1 ≦ 1.0 (3)
(In formulas (2) and (3), H1 represents the heat of fusion (J / g) at the time of the first temperature rise by differential scanning calorimetry. In formula (3), H2 represents the second time by differential scanning calorimetry. (The heat of fusion at the time of temperature rise (J / g) is shown.)   The first polyester resin and the second polyester resin are each a urethane-modified polyester resin in which at least two or more polyesters are bonded by a structural unit derived from a compound having an isocyanate group. The liquid developer set described in 1. The liquid developer set according to claim 1, wherein the liquid developer set satisfies the following condition 1 and / or condition 2.
Condition 1: The first toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surface of core particles containing a core resin, and the core resin is the first polyester resin. is there.
Condition 2: The second toner particles have a core-shell structure in which shell particles containing a shell resin are attached to or coated on the surface of the core particles containing the core resin, and the core resin is the second polyester resin. is there.   The liquid developer set according to claim 1, wherein the chromatic colorant is a cyan pigment.

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