JP6515587B2 - Liquid developer - Google Patents

Description

  The present invention relates to a liquid developer.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2013-3197) describes toner particles containing a polyester resin. This document describes that if the melting point of the solid obtained by drying the liquid developer is 55 ° C. or higher, document offset can be prevented, and it is derived from the structural unit derived from the acid component and the alcohol component It is described that the melting point of the solid of the liquid developer becomes 55 ° C. or higher if the total amount of structural units derived from aliphatic monomers in both structural units and the structural unit is 30 mol% or more.

  Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 2009-96994) and Patent Document 3 (Japanese Patent Application Laid-Open No. 2014-66887) disclose toner particles having a core / shell structure.

JP, 2013-3197, A JP, 2009-96994, A JP, 2014-66887, A

  Patent Document 1 describes that toner particles are fixed to a recording medium at 180 ° C., however, liquid developer is required to be fixed at a lower temperature (low-temperature fixability). In the liquid developer, unlike the dry developer, the particle size of toner particles can be controlled to 2 μm or less. Therefore, the amount of adhesion of the liquid developer to the recording medium can be significantly reduced compared to the amount of adhesion of the dry developer to the recording medium. This is an advantage over low temperature fixability. Further, as a method for realizing fixation at a low temperature, it has been proposed to improve the meltability of a resin contained in toner particles, or to use a resin having a high sharp melt property (for example, a polyester resin).

  When an amorphous polyester resin is used as a resin contained in toner particles, the softening point can be lowered by adjusting the molecular weight and the like of the amorphous polyester resin. Therefore, low temperature fixing (for example, fixing at 90 ° C.) is possible. However, when the softening point of the amorphous polyester resin is lowered, its glass transition point is also lowered, which causes the heat resistance of the toner particles to be lowered. For example, it becomes difficult to make the heat resistance temperature of the toner particles 50 ° C. or higher.

  On the other hand, the melting point of the crystalline polyester resin is lower than the softening point of the amorphous polyester resin. Therefore, when a crystalline polyester resin is used as the resin contained in the toner particles, fixing at low temperature is possible without reducing the heat resistance of the toner particles. Therefore, it is preferable to use a crystalline polyester resin as the resin contained in the toner particles.

  The crystalline polyester resin is mainly composed of an aliphatic monomer, and the amorphous polyester resin is mainly composed of an aromatic monomer. Here, since the resin composed of an aliphatic monomer is softer than the resin composed of an aromatic monomer, it has a tendency to be vulnerable to stress. Therefore, when a crystalline polyester resin is used as a resin contained in toner particles, the toner particles may be aggregated due to stress application in a developing device. The aggregation of toner particles is noticeable in the NIP portion of the developing device, between the roller and the roller, or between the roller and the blade.

  Further, in the liquid developer, since the resin contained in the toner particles is in contact with the insulating liquid, the resin swells in the insulating liquid and is likely to be plasticized, and therefore, is susceptible to stress. As a result, aggregation of toner particles is likely to occur.

  The present invention has been made in view of the foregoing point, and an object thereof is to achieve both the improvement of the low temperature fixability of toner particles and the improvement of the aggregation resistance of toner particles.

  A resin (amorphous polyester resin) composed of an aromatic monomer is harder than a resin (crystalline polyester resin) composed of an aliphatic monomer. Therefore, it is considered that the aggregation resistance of the toner particles can be enhanced by using an amorphous polyester resin as the resin contained in the toner particles. However, if it is attempted to fix at low temperature using only amorphous polyester resin as a resin contained in toner particles, the heat resistance of the toner particles is lowered.

  On the other hand, if only crystalline polyester resin is used as the resin contained in the toner particles, the toner particles can be fixed at a low temperature without reducing the heat resistance of the toner particles. However, the aggregation resistance of the toner particles is reduced.

  From the above, when using both crystalline polyester resin and amorphous polyester resin as the resin contained in the toner particles, the present inventors can lower the toner particles at low temperature without reducing the heat resistance of the toner particles. It was considered that the toner could be fixed and, further, the aggregation resistance of toner particles could be improved. Therefore, toner particles were formed using both the crystalline polyester resin and the amorphous polyester resin, and the characteristics of the toner particles were examined. Then, it was found that toner particles may be aggregated.

  The present inventors analyzed toner particles that did not aggregate and aggregated toner particles in order to determine the cause of such results. As a result, the crystalline polyester resin and the non-crystalline polyester resin were not compatible with the toner particles that did not aggregate, whereas the crystalline polyester resin and the non-crystalline polyester resin were in phase with each other in the aggregated toner particles. It was melting. The present inventors found that when the crystalline polyester resin and the amorphous polyester resin are compatible, the resin becomes soft due to the addition of the crystalline polyester resin, so that the aggregation resistance of the toner particles is not reduced. I think that.

  Further, in toner particles having a core / shell structure, a shell resin is provided on at least a part of the surface of the core particles including the core resin, and the shell resin is considered to contribute to the improvement of the dispersibility of the toner particles. . Based on the above consideration, the liquid developer of the present invention is completed.

  The liquid developer of the present invention comprises an insulating liquid and toner particles dispersed in the insulating liquid. The toner particles have a core / shell structure. The core / shell structure has a core particle containing a core resin, and a shell resin which is provided on at least a part of the surface of the core particle and is different from the core resin. The core resin contains 5% by mass or more and 30% by mass or less of the crystalline polyester resin and 70% by mass or more and 95% by mass or less of the amorphous polyester resin. The difference between the acid value of the crystalline polyester resin and the acid value of the amorphous polyester resin is 15 mg KOH / g or more and 100 mg KOH / g or less. Here, "a shell resin which is a resin different from the core resin" means that at least one of the chemical structure and the molecular weight differs between the core resin and the shell resin.

  The polyester resin is synthesized by the polycondensation reaction of a carboxylic acid (constituent unit derived from an acid component) and an alcohol (constituent unit derived from an alcohol component). Therefore, a portion derived from a carboxylic acid is a structural unit derived from an acid component, a portion derived from an alcohol is a structural unit derived from an alcohol component, and the polyester resin is configured by repeating these structural units.

  “Crystalline polyester resin” means that the content ratio of structural units derived from aliphatic monomers in both structural units derived from alcohol components and structural units derived from acid components is 50% by mass or more Means The content ratio of the structural unit derived from the aliphatic monomer in both structural units derived from the alcohol component and the structural unit derived from the acid component is preferably 60% by mass or more, more preferably 70% by mass It is the above, More preferably, it is 80 mass% or more.

  The “constituent unit derived from an alcohol component” means one having a hydrogen atom removed from a hydroxyl group (OH group) of alcohol, and includes one having a hydrogen atom removed from at least one hydroxyl group contained in alcohol. The "constituent unit derived from an acid component" means that the hydroxyl group is removed from the carboxyl group (COOH group) of the carboxylic acid, and the one in which the hydroxyl group is removed from at least one carboxyl group contained in the carboxylic acid Including. The "aliphatic monomers" include aliphatic carboxylic acids, lower alkyl esters of aliphatic carboxylic acids, acid anhydrides of aliphatic carboxylic acids, and aliphatic alcohols. The "aliphatic carboxylic acid" means a carboxylic acid having no aromatic ring in the molecule. The "fatty alcohol" means an alcohol having no aromatic ring in the molecule.

  In the "non-crystalline polyester resin", the content ratio of the structural unit derived from the aromatic monomer in both structural units derived from the alcohol component and the structural unit derived from the acid component is 50% by mass or more It means that. The content ratio of the structural unit derived from the aromatic monomer in both the structural units derived from the alcohol component and the structural unit derived from the acid component is preferably 60% by mass or more, more preferably 70% by mass It is the above, More preferably, it is 80 mass% or more.

  The "aromatic monomers" include aromatic carboxylic acids, lower alkyl esters of aromatic carboxylic acids, acid anhydrides of aromatic carboxylic acids, and aromatic alcohols. The "aromatic carboxylic acid" means a carboxylic acid having an aromatic ring in the molecule. The "aromatic alcohol" means an alcohol having an aromatic ring in the molecule.

  "Acid value of crystalline polyester resin" refers to the method described in JIS K 0070: 1992 (Test method of acid value, saponification number, ester number, iodine value, hydroxyl value and unsaponifiable matter of chemical products) Mean the acid value of the crystalline polyester resin measured based on the amount of carboxyl groups contained in the crystalline polyester resin. The “carboxyl group contained in the crystalline polyester resin” is based on the amount of the carboxyl group residue which has not reacted with the hydroxyl group in the condensation polymerization reaction when synthesizing the crystalline polyester resin.

  The "acid value of non-crystalline polyester resin" means the acid value of non-crystalline polyester resin measured according to the method described in JIS K 0070: 1992, and is included in the non-crystalline polyester resin. Based on the amount of carboxyl groups. The “carboxyl group contained in the non-crystalline polyester resin” is based on the amount of the carboxyl group residue which has not reacted with the hydroxyl group in the condensation polymerization reaction when synthesizing the non-crystalline polyester resin.

  Preferably, the acid value of the core resin is 20 mg KOH / g or more and 100 mg KOH / g or less. The "acid value of the core resin" means the acid value of the core resin measured according to the method described in JIS K 0070: 1992 above, and is based on the amount of carboxyl groups contained in the core resin. The "carboxyl group contained in the core resin" is based on the amount of carboxyl group residue which has not reacted with the hydroxyl group in the condensation polymerization reaction when synthesizing the crystalline polyester resin and the non-crystalline polyester resin.

  Preferably, the acid value of the crystalline polyester resin is larger than the acid value of the amorphous polyester resin.

  In the present invention, it is possible to simultaneously improve the low temperature fixability of the toner particles and the aggregation resistance of the toner particles.

It is a side view of the apparatus used in order to evaluate the aggregation resistance of a liquid developer. FIG. 1 is a schematic conceptual view of a part of an electrophotographic image forming apparatus.

[Configuration of liquid developer]
The liquid developer of the present embodiment is a liquid developer for electrophotography, a paint, a liquid for electrostatic recording used in an electrophotographic image forming apparatus (described later) such as a copying machine, a printer, a digital printing machine or a simple printing machine. It is useful as a developer, an oil-based ink for an ink jet printer, or an ink for electronic paper. The liquid developer of the present embodiment includes an insulating liquid and toner particles dispersed in the insulating liquid, and preferably includes 10 to 50% by mass of toner particles and 50 to 90% by mass of insulating liquid. The liquid developer of this embodiment may contain any component different from the insulating liquid and the toner particles. Such optional components include, for example, toner dispersants, charge control agents or thickeners.

<Toner particles>
The toner particles of the present embodiment have a core / shell structure. The core / shell structure has a core particle containing a core resin, and a shell resin which is provided on at least a part of the surface of the core particle and is a resin different from the core resin. In such toner particles, the shell resin generates a repulsive force between the toner particles. Thus, the aggregation resistance of the toner particles can be enhanced as compared to toner particles having no core / shell structure.

  In the toner particles of the present embodiment, the colorant is preferably dispersed in at least one of the core resin and the shell resin, and more preferably 50 to 90% by mass of the resin (core resin and shell resin) It has 10 to 50% by mass of a colorant. The toner particles of the present embodiment may contain any component different from the resin and the colorant. Such optional components include, for example, pigment dispersants, waxes or charge control agents.

  Preferably, the median diameter D50 (hereinafter referred to as “median diameter D50 of toner particles”) when the particle size distribution of toner particles is measured on a volume basis is 0.5 μm or more and 5.0 μm or less. The median diameter D50 is smaller than the particle diameter of toner particles contained in the conventional dry type developer, and is one of the features of the present embodiment. If the median diameter D50 of the toner particles is 0.5 μm or more, the particle diameter of the toner particles can be secured, the mobility of the toner particles in an electric field can be improved, and the developability can be enhanced. When the median diameter D50 of the toner particles is 5.0 μm or less, the dispersibility of the toner particles can be secured, and the image quality can be enhanced. More preferably, the median diameter D50 of the toner particles is 1.0 μm or more and 2.0 μm or less.

  Preferably, the average circularity of the toner particles is 0.85 to 0.95, and the standard deviation of the circularity of the toner particles is 0.01 to 0.1. This improves the transferability and the cleaning ability. The term "circularity" means a numerical value obtained by dividing the peripheral length of a circle having an area equal to the particle area projected in two dimensions by the particle peripheral length. The "average circularity" means the arithmetic mean value of the calculated circularity.

  For example, using a flow type particle image analyzer (product number "FPIA-3000S" manufactured by Sysmex Corporation), the median diameter D50 of toner particles, the average circularity of toner particles, and the standard deviation of circularity of toner particles It is measurable. In this analyzer, it is possible to use the solvent as a dispersion medium as it is. Therefore, if this analyzer is used, it is possible to measure the state of toner particles in a state closer to the actual dispersed state than in the water system.

  Preferably, the mass ratio of the core resin to the shell resin [(mass of core resin): (mass of shell resin)] is 99: 1 to 30:70. The mass ratio of the core resin to the shell resin is more preferably 98: 2 to 35:65, and still more preferably 97 in view of the uniformity of the particle diameter of the toner particles and the heat resistance stability of the liquid developer. : 3 to 50: 50. When the mass of the shell resin is 1% by mass or more of the total of the mass of the core resin and the mass of the shell resin, the blocking resistance of the toner particles can be maintained high. If the mass of the shell resin is 70% by mass or less of the total of the mass of the core resin and the mass of the shell resin, the uniformity of the particle diameter of the toner particles can be maintained high.

<Core resin>
(Content of crystalline polyester resin and content of amorphous polyester resin)
The core resin contains 5% by mass or more and 30% by mass or less of the crystalline polyester resin and 70% by mass or more and 95% by mass or less of the amorphous polyester resin. If the content of the crystalline polyester resin (the ratio of the mass of the crystalline polyester resin to the mass of the core resin) is 5% by mass or more, the content of the resin having a low melting point (crystalline polyester resin) can be secured. It becomes possible to establish If the content of the crystalline polyester resin is 30% by mass or less, the content of the hard resin (amorphous polyester resin) can be secured, so that the aggregation resistance of the toner particles can be enhanced. Preferably, the content of the crystalline polyester resin is 5% by mass or more and 25% by mass or less. As a result, since the content of the hard resin can be further secured, the aggregation resistance of the toner particles can be further enhanced.

  If the content of the amorphous polyester resin (the ratio of the mass of the amorphous polyester resin to the mass of the core resin) is 70% by mass or more, the content of the hard resin (amorphous polyester resin) can be secured, The aggregation resistance of toner particles can be enhanced. If the content of the amorphous polyester resin is 95% by mass or less, the content of the resin (crystalline polyester resin) having a low melting point can be secured, and therefore, fixing at low temperature is possible. Preferably, the content of the amorphous polyester resin is 75% by mass or more and 95% by mass or less. As a result, since the content of the hard resin can be further secured, the aggregation resistance of the toner particles can be further enhanced.

The content of the crystalline polyester resin and the content of the non-crystalline polyester resin are ¹ H-NMR using a Fourier transform nuclear magnetic resonance device (FT-NMR) (trade name: “Lambda 400”, manufactured by Nippon Denshi Co., Ltd.) The analysis is performed and it can be determined from the integral ratio. A chloroform-d (deuterated chloroform) solvent can be used as a measurement solvent. Content ratio of constituent unit derived from aliphatic monomer in both constituent units of constituent unit derived from alcohol component and constituent unit derived from acid component, and composition derived from constituent unit derived from alcohol component and acid component The content ratio of the structural unit derived from the aromatic monomer in both structural units and the unit can also be measured by the same method.

(Difference in acid value)
The difference between the acid value of the crystalline polyester resin and the acid value of the non-crystalline polyester resin (hereinafter sometimes referred to as the “difference in acid value”) is 15 mg KOH / g to 100 mg KOH / g. If the difference in the acid value is 15 mg KOH / g or more, the difference between the amount of carboxyl groups contained in the crystalline polyester resin and the amount of carboxyl groups contained in the non-crystalline polyester resin becomes large. The difference between the SP (Solubility Parameter) value and the SP value of the amorphous polyester resin becomes large. This reduces the affinity between the crystalline polyester resin and the amorphous polyester resin. That is, it becomes difficult for the crystalline polyester resin and the amorphous polyester resin to be compatible with each other. Preferably, the difference in acid value is 20 mg KOH / g or more.

  Here, the content of the crystalline polyester resin is lower than the content of the amorphous polyester resin. Therefore, the crystalline polyester resin (soft resin) comes to be surrounded by the amorphous polyester resin (hard resin) (formation of a sea-island structure), whereby the aggregation resistance of the toner particles is enhanced.

  Various methods can be considered as a method of enlarging the difference between the SP value of the crystalline polyester resin and the SP value of the amorphous polyester resin. However, if the difference in acid value is increased, the difference between the SP value of the crystalline polyester resin and the SP value of the non-crystalline polyester resin can be effectively increased. That is, it becomes difficult for the crystalline polyester resin and the amorphous polyester resin to be compatible with each other.

  If the difference in acid value is 100 mg KOH / g or less, formation of a three-dimensional structure (crosslinked structure) by carboxyl groups can be prevented in the core resin. Therefore, since the melting property of the core resin at low temperature can be secured, fixing at low temperature becomes possible. In fact, it is difficult to make the difference in acid value greater than 100 mg KOH / g.

  The acid value of the crystalline polyester resin may be larger than that of the amorphous polyester resin as long as the difference in the acid value is 15 mg KOH / g to 100 mg KOH / g, and the acid of the amorphous polyester resin may be The value may be larger than the acid value of the crystalline polyester resin. However, in toner particles having a core / shell structure, the acid value of the crystalline polyester resin is preferably larger than the acid value of the amorphous polyester resin. As a result, the non-crystalline polyester resin has lower polarity than the crystalline polyester resin, so that the non-crystalline polyester resin is oriented on the surface of the core particle. Thus, the surface of the toner particles becomes hard. Therefore, the aggregation resistance of the toner particles can be further enhanced.

  In detail, as described later, the liquid developer of the present embodiment is produced according to the following method. First, at least a core resin is dissolved in a first solvent to prepare a core solution, and a shell resin is dispersed in a second solvent to prepare a shell dispersion. Next, the core solution and the shell dispersion are mixed. Thereby, core particles containing the core resin are formed, and the shell resin adheres to at least a part of the surface of the core particles. Thereafter, the first solvent is removed to obtain the liquid developer of the present embodiment. Here, an organic solvent with low polarity is often used as the second solvent. Therefore, a component with low polarity among core resin is oriented on the surface of core particle.

  When the acid value of the crystalline polyester resin is larger than the acid value of the amorphous polyester resin, the amorphous polyester resin has lower polarity than the crystalline polyester resin, so the amorphous polyester resin has a core. It will be oriented to the surface of the particle. As a result, the surface of the toner particles becomes hard, so that the aggregation resistance of the toner particles can be further enhanced.

  The acid value of the polyester resin can be adjusted according to the following method. For example, a mixed mole of a monomer serving as a constituent unit derived from an alcohol component and a monomer serving as a constituent unit derived from an acid component, which changes the type of the constituent unit derived from the alcohol component or the type of the constituent unit derived from the acid component Examples include changing the ratio or changing the conditions of the condensation reaction. By adopting any of these methods, the amount (molar amount) of the hydroxyl group contained in the monomer serving as the constituent unit derived from the alcohol component is reduced to the amount of the carboxyl group contained in the monomer serving as the constituent unit derived from the acid component. Make more than the amount (molar amount). Thus, a polyester resin having hydroxyl groups at both ends (hereinafter referred to as "intermediate of polyester resin") is synthesized. Intermediate of polyester resin and polyvalent carboxylic acid by adjusting the magnitude relationship between the amount (molar amount) of hydroxyl group contained in the intermediate of polyester resin and the amount (molar amount) of carboxyl group contained in polyvalent carboxylic acid And the acid value of the polyester resin can be optimized. Here, "polycarboxylic acid" refers to a carboxylic acid having two or more functional groups (eg, carboxyl group), and includes aliphatic polycarboxylic acid and aromatic polycarboxylic acid.

  For example, the intermediate of crystalline polyester resin is synthesized according to the synthesis method of intermediate of polyester resin. An intermediate of the synthesized crystalline polyester resin is reacted with an aliphatic polyvalent carboxylic acid. At this time, if the amount (molar amount) of the carboxyl group contained in the aliphatic polyvalent carboxylic acid is larger than the amount (molar amount) of the hydroxyl group contained in the intermediate of the crystalline polyester resin, a crystal having a high acid value Polyester resin is obtained.

  Further, the intermediate of the amorphous polyester resin is synthesized according to the synthesis method of the intermediate of the polyester resin. An intermediate of the synthesized amorphous polyester resin is reacted with an aliphatic polyvalent carboxylic acid or an aromatic polyvalent carboxylic acid. At this time, the amount (molar amount) of the carboxyl group contained in the aliphatic polyvalent carboxylic acid or the aromatic polyvalent carboxylic acid is less than the amount (molar amount) of the hydroxyl group contained in the intermediate of the amorphous polyester resin If so, an amorphous polyester resin with a low acid value can be obtained.

(Acid value of core resin)
Preferably, the acid value of the core resin is 20 mg KOH / g or more and 100 mg KOH / g or less. When the acid value of the core resin is 20 mg KOH / g or more, the adhesiveness between the toner particles and the recording medium in the state of being dispersed in the insulating liquid can be secured. Thereby, the fixing strength of the toner particles to the recording medium can be secured. More preferably, the acid value of the core resin is 30 mg KOH / g or more. In addition, it is difficult to make the acid value of core resin larger than 100 mgKOH / g.

  The acid value of the core resin can be made 20 mg KOH / g or more by adjusting the acid value of the crystalline polyester resin or the acid value of the non-crystalline polyester resin according to the method described above.

(Constituent unit)
Examples of aliphatic monomers to be structural units derived from an acid component include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonane Dicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid An acid or 1,18-octadecane dicarboxylic acid etc. are mentioned. These lower alkyl esters may be used, or these acid anhydrides may be used. From the viewpoint of promoting the crystallinity of the polyester resin, it is more preferable to use adipic acid, sebacic acid, 1,10-decanedicarboxylic acid or 1,12-dodecanedicarboxylic acid. As such an aliphatic monomer, any of the above may be used alone, or two or more of any of the above may be used in combination.

  Examples of aliphatic monomers to be structural units derived from alcohol components include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and the like. , 7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1 , 14-tetradecanediol, 1,18-octadecanediol, or 1,20-eicosanediol and the like. From the viewpoint of promoting the crystallinity of the polyester resin, it is preferable to use ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol or 1,10-decanediol . As such an aliphatic monomer, any of the above may be used alone, or two or more of any of the above may be used in combination.

  Examples of aromatic monomers to be structural units derived from acid components include aromatic polyvalent carboxylic acids, lower alkyl esters of aromatic polyvalent carboxylic acids, and acid anhydrides of aromatic polyvalent carboxylic acids. Can. Specifically, terephthalic acid, isophthalic acid, orthophthalic acid, 5-tert-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, or trimellitic acid (having 3 functional groups) And the like. From the viewpoint of easy availability, it is preferable to use terephthalic acid, isophthalic acid or 5-tert-butylisophthalic acid.

  Examples of aromatic monomers to be structural units derived from alcohol components include aromatic polyhydric alcohols. Specifically, an alkylene oxide adduct of bisphenol A represented by the following chemical formula (I) can be mentioned.

In the above chemical formula (I), R ¹ and R ² each independently represent a C ² or C 3 alkylene group. m and n each independently represent 0 or a positive integer. The sum of m and n is 1 or more and 16 or less.

  The number average molecular weight (Mn) of the crystalline polyester resin is preferably 1,000 or more and 25,000 or less, and the mass average molecular weight (Mw) of the crystalline polyester resin is preferably 2,000 or more and 200,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 1,000 or more and 25,000 or less, and the mass average molecular weight (Mw) of the amorphous polyester resin is preferably 2,000 or more and 200,000 or less. The number average molecular weight (Mn) and the mass average molecular weight (Mw) can be measured by GPC (Gel Permeation Chromatography, gel permeation chromatography).

  The core resin may contain less than 10% by mass of resins other than the crystalline polyester resin and the amorphous polyester resin. As resin other than crystalline polyester resin and non-crystalline polyester resin, styrene-acrylic resin, a urethane resin, an epoxy resin etc. can be mentioned, for example. When the content is 10% by mass or more, it may be difficult to regularly arrange the molecular chains of the polyester resin.

(Crystalline and amorphous)
As described above, the core resin contains a crystalline polyester resin and an amorphous polyester resin.

  In the present specification, “crystalline” refers to the ratio (Tm / Ta) of the softening point of the resin (hereinafter referred to as “Tm”) to the maximum peak temperature of the heat of fusion of the resin (hereinafter referred to as “Ta”) It means that it is 0.8 or more and 1.55 or less, and the result obtained by differential scanning calorimetry (DSC (Differential Scanning Calorimetry)) does not show a step-like endothermic change but has a clear endothermic peak. It means that. Further, in the present specification, “amorphous” means that the ratio of Tm to Ta (Tm / Ta) is greater than 1.55. Tm and Ta can be measured by the following method.

  Tm can be measured using a high-rise flow tester (for example, product number "CFT-500D" manufactured by Shimadzu Corporation). Specifically, while heating 1 g of the measurement sample at a heating rate of 6 ° C./min, a load of 1.96 MPa is applied to the measurement sample by the plunger, and the measurement sample is extruded from a nozzle of 1 mm in diameter and 1 mm in length. . Then, the relationship between the "plunger descent amount (flow value)" and the "temperature" is drawn on a graph. The temperature when the amount of drop of the plunger is half of the maximum value of the amount of drop is read from the graph, and this value (the temperature when half of the measurement sample is pushed out of the nozzle) is taken as Tm.

  Ta can be measured using a differential scanning calorimeter (for example, product number “DSC 210” manufactured by Seiko Instruments Inc.). Specifically, first, a sample used to measure Ta is pretreated. The sample is melted at 130 ° C. and then ramped down from 130 ° C. to 70 ° C. at a rate of 1.0 ° C./min and then ramped down from 70 ° C. to 10 ° C. at a rate of 0.5 ° C./min. Next, the sample is heated at a temperature rising rate of 20 ° C./min by DSC method to measure the endothermic change of the sample, and the relationship between the “endothermic amount” and the “temperature” is drawn on a graph. At this time, the temperature of the endothermic peak observed at 20 to 100 ° C. is Ta ′. When there are a plurality of endothermic peaks, the temperature of the peak having the largest endothermic amount is Ta '. Then, the sample is stored at (Ta′-10) ° C. for 6 hours, and then stored at (Ta′-15) ° C. for 6 hours.

  When the pretreatment of the sample is completed, the sample subjected to the pretreatment is cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min by DSC method, and then heated at a temperature rising rate of 20 ° C./min. From the endothermic change measured in this manner, the relationship between the "endothermic amount" and the "temperature" is drawn on a graph. Then, the temperature at which the heat absorption amount reaches the maximum value is taken as the maximum peak temperature (Ta) of the heat of fusion.

Preferably, the heat of fusion of the crystalline polyester resin (crystalline polyester resin contained in the core resin) measured by the DSC method satisfies the following formulas (1) and (2).
5 ≦ H1 ≦ 100 (1)
0.2 ≦ H2 / H1 ≦ 1.0 Equation (2)
In the above formulas (1) and (2), H1 represents the heat of fusion (J / g) at the first temperature rise by the DSC method, and H2 represents the heat of fusion at the second temperature rise by the DSC method (J / g) Represents.

  H1 is an index of the melting rate of the crystalline polyester resin. In general, a resin having a heat of fusion has a sharp melting property and therefore melts with less energy. When H1 of the crystalline polyester resin exceeds 100, it is difficult to reduce the fixing energy. As a result, the fixability of the toner particles is reduced. On the other hand, if H1 of the crystalline polyester resin is less than 5, the fixing energy is too small, so document offset tends to occur. However, if H1 of the crystalline polyester resin satisfies the above equation (1), it is possible to prevent the occurrence of document offset and to prevent the deterioration of the fixing property of toner particles. Preferably, 15 ≦ H1 ≦ 80, and more preferably 35 ≦ H1 ≦ 70.

  H2 / H1 in the above equation (2) is an index of the crystallization rate of the crystalline polyester resin. Generally, in the case of melting after cooling resin particles after melting resin particles (resin particles), if there is a portion not crystallized in the crystalline component in the resin particles, the resistance value of the resin particles is This causes problems such as lowering or plasticizing of the resin particles. When such a defect occurs, the performance of the resin particles obtained by cooling may differ from the originally designed performance. From the above, it is necessary to rapidly crystallize the crystal component in the resin particle so as not to affect the performance of the resin particle. H2 / H1 is more preferably 0.3 or more, still more preferably 0.4 or more. In addition, since H2 / H1 approaches 1.0 if the crystallization rate of the crystalline polyester resin is fast, H2 / H1 preferably has a value close to 1.0.

  In addition, although H2 / H1 in the said Numerical formula (2) does not exceed 1.0 theoretically, it may exceed 1.0 in the measured value by DSC method. Even when the measured value (H2 / H1) by the DSC method exceeds 1.0, the above formula (2) is satisfied.

  H1 and H2 can be measured in accordance with JIS-K7122 (1987) "Method for measuring transition heat of plastic". Specifically, first, 5 mg of crystalline polyester resin is collected and placed in an aluminum pan. Using a differential scanning calorimeter (for example, product number “RDC 220” manufactured by SII Nano Technology Co., Ltd. or product number “DSC 20” manufactured by Seiko Instruments Inc., etc.), melting is performed at a heating rate of 10 ° C. per minute. The temperature (melting point) of the endothermic peak of the crystalline polyester resin according to the above is measured, and the area S1 of the endothermic peak is determined. Then, H1 can be calculated from the obtained endothermic peak area S1. After calculating H 1 and cooling to 0 ° C. at a cooling rate of 90 ° C./min, measure the temperature (melting point) at the endothermic peak of the crystalline polyester resin by melting at a temperature rising rate of 10 ° C./min. The area S2 of the endothermic peak is determined. Then, H2 can be calculated from the obtained endothermic peak area S2.

  H1 and H2 can also be measured according to the method shown below using a differential scanning calorimeter (for example, product number "DSC 210" manufactured by Seiko Instruments Inc.). First, the standard sample and the crystalline polyester resin are heated at a rate of 10 ° C./minute from 0 ° C. to 180 ° C., and the difference between the heat amount of the standard sample and the heat amount of the crystalline polyester resin is measured. The difference between the measured heat amounts is the heat of fusion H1 of the crystalline polyester resin according to the DSC method. Then, after cooling to 0 ° C. at a cooling rate of 90 ° C./min, the standard sample and the crystalline polyester resin are heated at a rate of 10 ° C./min from 0 ° C. to 180 ° C. Measure the difference with the heat quantity of the resin. The difference of the measured heat quantity is the heat of fusion H2 of the crystalline polyester resin according to the DSC method.

<Core particle>
The core particle contains a core resin, and may further contain a colorant or an optional component such as a pigment dispersant, a wax or a charge control agent.

  From the viewpoint of easily controlling the ratio of the particle diameter of the core particle and the particle diameter of the shell particle (described later) to a preferable range, the median diameter D50 when measuring the particle size distribution of the core particle on a volume basis The median diameter D50 ′ ′ is preferably 0.1 μm to 300 μm, more preferably 0.5 μm to 250 μm, and still more preferably 1 μm to 200 μm.

  The median diameter D50 of the core particle is a laser diffraction type particle size distribution measuring apparatus (for example, product number “LA-920” manufactured by Horiba, Ltd. or product number “Multisizer III” manufactured by Beckman Coulter, Inc.) or as an optical system It can be measured using a particle size distribution measuring apparatus (product number "ELS-800" manufactured by Otsuka Electronics Co., Ltd.) using a laser Doppler method or the like. When a difference occurs in the measured value when the median diameter D50 of the core particle is measured using different measurement, the measurement using a particle size distribution measuring apparatus (product number "ELS-800" manufactured by Otsuka Electronics Co., Ltd.) Adopt a value.

<Shell resin>
The shell resin has the function of adhering to the surface of the core particle to enhance the dispersibility of the core particle. That is, the shell resin functions as a polymer dispersant. The shell resin may be either a thermoplastic resin or a thermosetting resin. For example, vinyl resin, polyurethane resin, epoxy resin, polyamide resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline It is preferable that it is resin, an ionomer resin, or polycarbonate resin. The shell resin may be a polyester resin made of a component different from the core resin.

  The shell resin is preferably a vinyl resin, a polyester resin, a polyurethane resin, or an epoxy resin, and more preferably a vinyl resin, from the viewpoint of easily controlling the shape of the toner particles at the time of production of the toner particles. The shell resin may be composed of one of these resins, or may be composed of a mixture of two or more resins. Below, vinyl resin is demonstrated.

(Vinyl resin)
The vinyl resin may be a homopolymer obtained by homopolymerizing a monomer having a polymerizable double bond (a homopolymer including a binding unit derived from a vinyl monomer), or a polymerizable double bond It may be a copolymer obtained by copolymerizing two or more kinds of monomers (copolymer containing a bonding unit derived from a vinyl monomer). As a monomer which has a polymerizable double bond, the following (1)-(9) is mentioned, for example.

(1) Hydrocarbon having polymerizable double bond (1-1) Aliphatic hydrocarbon having polymerizable double bond (1-1-1) Chain-like aliphatic hydrocarbon having polymerizable double bond Polymerization Aliphatic hydrocarbon having a heterocyclic double bond is, for example, an alkene having 2 to 30 carbon atoms (eg, ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene or octadecene) Or an alkadiene having 4 to 30 carbon atoms (eg, butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, etc.) and the like.

(1-1-2) Cyclic Aliphatic Hydrocarbon Having a Polymerizable Double Bond The cyclic aliphatic hydrocarbon having a polymerizable double bond is, for example, a monocycloalkene having a carbon number of 6 or more and 30 or less, or Cycloalkene (eg, cyclohexene, vinylcyclohexene or ethylidene bicycloheptene), or monocycloalkadiene or dicycloalkadiene having 5 to 30 carbon atoms (eg, monocyclopentadiene or dicyclopentadiene) Is preferred.

(1-2) Aromatic hydrocarbon having a polymerizable double bond Aromatic hydrocarbons having a polymerizable double bond are, for example, styrene, a hydrocarbyl of styrene (for example, an alkyl having 1 to 30 carbon atoms) , Cycloalkyl, aralkyl or alkenyl) (eg, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, It is preferable that divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene or the like) or vinylnaphthalene or the like.

(2) Monomers Having a Carboxyl Group and a Polymerizable Double Bond and Salts Thereof The monomers having a carboxyl group and a polymerizable double bond are, for example, unsaturated monocarboxylic acids having 3 to 15 carbon atoms [eg, (Meth) acrylic acid, crotonic acid, isocrotonic acid or cinnamic acid etc., unsaturated dicarboxylic acid having 3 to 30 carbon atoms (anhydride) [eg (anhydride), maleic acid, fumaric acid, itaconic acid ( Anhydride) Citraconic acid or mesaconic acid etc.], monoalkyl (C1 or more and 10 or less) ester of unsaturated dicarboxylic acid having 3 to 10 carbon atoms (eg, monomethyl ester of maleic acid, monodecyl ester of maleic acid, fumar) Acid monoethyl ester, itaconic acid monobutyl ester or citraconic acid monodecyl ester etc. It is preferable. As used herein, "(meth) acrylic" means at least one of acrylic and methacrylic.

  The salts of the above monomers are, for example, alkali metal salts (eg, sodium salt or potassium salt etc.), alkaline earth metal salts (eg calcium salt or magnesium salt etc.), ammonium salt, amine salt or quaternary ammonium salt It is preferable that it is salt etc.

  The amine salt is not particularly limited as long as it is an amine compound, and for example, a primary amine salt (eg, ethylamine salt, butylamine salt or octylamine salt), a secondary amine salt (eg, diethylamine salt or dibutylamine salt) And the like, or a tertiary amine salt such as triethylamine salt or tributylamine salt, etc.

  The quaternary ammonium salt is preferably, for example, tetraethyl ammonium salt, triethyl lauryl ammonium salt, tetrabutyl ammonium salt, or tributyl lauryl ammonium salt.

  Examples of salts of monomers having a carboxyl group and a polymerizable double bond include sodium acrylate, sodium methacrylate, monosodium maleate, disodium maleate, potassium acrylate, potassium methacrylate, monopotassium maleate, acrylic Lithium acid, cesium acrylate, ammonium acrylate, calcium acrylate or aluminum acrylate is preferably used.

(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) A hydroxyl group and a polymerizable double bond Although it does not list a specific example about said monomer (3)-(5), it can be used as a monomer of vinyl resin.

(6) Nitrogen-containing monomer having a polymerizable double bond (6-1) Monomer having an amino group and a polymerizable double bond A monomer having an amino group and a polymerizable double bond is, for example, aminoethyl (meth) ) Acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl methacrylate, N-aminoethyl (meth) acrylamide, (meth) allylamine, morpholinoethyl (meth) acrylate, 4-vinylpyridine , 2-vinylpyridine, crotylamine, N, N-dimethylaminostyrene, methyl-α-acetoaminoacrylate, vinylimidazole, N-vinylpyrrole, N-vinylthiopyrrolidone, N-arylphenylenediamine, aminocarbazole, aminothiazole Aminoindole, aminopyrrole, it is preferable that in such aminoimidazole or amino mercaptothiazole.

  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 the “salt of the above-mentioned monomer” in the above-mentioned “(2) a monomer having a carboxyl group and a polymerizable double bond and a salt thereof”.

(6-2) Monomer Having Amide Group and Polymerizable Double Bond A monomer having an amide group and a polymerizable double bond is, for example, (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl acrylamide , Diacetone acrylamide, N-methylol (meth) acrylamide, N, N'- methylene-bis (meth) acrylamide, cinnamic acid amide, N, N- dimethyl acrylamide, N, N- dibenzyl acrylamide, methacryl formamide, N- Preferred is methyl-N-vinyl acetamide or N-vinyl pyrrolidone.

(6-3) A C3-10 Monomer Having a Nitrile Group and a Polymerizable Double Bond A monomer having 3 to 10 carbon atoms having a nitrile group and a polymerizable double bond is, for example, It is preferable that they are acrylonitrile, cyanostyrene or cyanoacrylate etc.

(6-4) A C8 to C12 Monomer Having a Nitro Group and a Polymerizable Double Bond A monomer having 8 to 12 carbon atoms having a nitro group and a polymerizable double bond is, for example, nitrostyrene And the like.

(7) A C6 to C18 Monomer Having an Epoxy Group and a Polymerizable Double Bond (8) A C2 to C16 Monomer Having a Halogen Element and a Polymerizable Double Bond The above (7) and (7) Although no specific example is listed about 8), it can be used as a monomer of vinyl resin.

(9) Ester having 4 to 16 carbon atoms having a polymerizable double bond The ester having 4 to 16 carbon atoms having a polymerizable double bond is, for example, 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, and having 1 to 11 carbon atoms Alkyl (meth) acrylates having the following alkyl groups [eg methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate or 2-ethylhexyl ( (Meth) acrylate etc.], dialkyl fumarate (2 alkyl groups are linear alkyl groups having 2 to 8 carbon atoms, branched alkyl groups or alicyclic alkyl groups), dialkyl maleates (2 Alkyl groups are linear alkyl groups having 2 to 8 carbon atoms, branched alkyl groups or alicyclic alkyl groups), poly (meth) allyloxyalkanes (eg, diaryloxyethane, Monomers having a triaryloxyethane, tetraaryloxyethane, tetraaryloxypropane, tetraaryloxybutane or tetramethalyloxyethane), a polyalkylene glycol chain and a polymerizable double bond [eg, polyethylene glycol (Mn = 300) Mono (meth) acrylate, polypropylene glycol (Mn = 500) monoaclear Methyl alcohol ethylene oxide (hereinafter referred to as “ethylene oxide” as “EO”) 10 molar adduct (meth) acrylate or lauryl alcohol EO 30 molar adduct (meth) acrylate etc.], or poly (meth) acrylates { For example, 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] It is preferable that it is glycol di (meth) acrylate etc.] etc. As used herein, “(meth) allilo” means at least one of allilo and metalillo.

  Specific examples of the vinyl resin include, for example, styrene- (meth) acrylic acid ester copolymer, styrene-butadiene copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer, styrene-acrylonitrile copolymer Combined, styrene- (anhydride) maleic acid copolymer, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid-divinylbenzene copolymer, or styrene-styrene sulfonic acid- (meth) acrylic acid An acid ester copolymer etc. are mentioned.

  The vinyl resin may be a homopolymer or copolymer of a monomer having a polymerizable double bond of the above (1) to (9), or a polymerizable double bond of the above (1) to (9) And a monomer having a first molecular chain and a polymerizable double bond may be polymerized. The first molecular chain has affinity to the insulating liquid, and, for example, a linear hydrocarbon chain having 12 to 27 carbon atoms, a branched hydrocarbon chain having 12 to 27 carbon atoms And a fluoroalkyl chain having 4 to 20 carbon atoms, a polydimethylsiloxane chain, or the like. The difference between the SP value of the monomer having the first molecular chain and the polymerizable double bond and the SP value of the insulating liquid is preferably 2 or less. As used herein, "SP value" refers to the method by Fedors [Polym. Eng. Sci. 14 (2) 152, (1974)] is shown.

  The monomer having the first molecular chain and the polymerizable double bond is preferably, for example, the first to third monomers shown below. The monomer having the first molecular chain and the polymerizable double bond may be any of the first to third monomers, or a combination of two or more of the first to third monomers. It may be.

  The first monomer is a monomer having a linear hydrocarbon chain having 12 to 27 carbon atoms (preferably 16 to 25 carbon atoms) and a polymerizable double bond, and, for example, an unsaturated monocarboxylic acid Or a mono-linear alkyl (alkyl carbon number of at least 12 carbon atoms) ester of unsaturated dicarboxylic acid. The unsaturated monocarboxylic acid and unsaturated dicarboxylic acid are preferably vinyl monomers containing a carboxyl group and having 3 to 24 carbon atoms, and examples thereof include (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid and itaconic acid. It is preferably an acid or citraconic acid or the like. Specific examples of the first monomer include, for example, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate or (meth) acrylic Acid eicosyl and the like.

  The second monomer is a monomer having a branched hydrocarbon chain having 12 to 27 carbon atoms (preferably 16 to 25 carbon atoms) and a polymerizable double bond, for example, unsaturated monocarboxylic acid Mono-branched alkyl (alkyl having a carbon number of 12 or more and 27 or less) ester or mono-branched alkyl of an unsaturated dicarboxylic acid (alkyl having a carbon number of 12 to 27 or less) ester or the like. The unsaturated monocarboxylic acid and unsaturated dicarboxylic acid are as described for the first monomer. As a specific example of a 2nd monomer, 2-decyl tetradecyl (meth) acrylate etc. are mentioned, for example.

  The third monomer is a monomer having a fluoroalkyl chain having 4 to 20 carbon atoms and a polymerizable double bond. Specific examples of the third monomer include, for example, those in which a hydrocarbon chain is substituted with a fluoroalkyl chain in the specific example of the first monomer or the specific example of the second monomer.

(Physical properties of shell resin)
The Mn of the shell resin is preferably 100 or more and 5,000,000 or less, more preferably 200 or more and 5,000,000 or less, and still more preferably 500 or more and 500000 or less. The Mn of the shell resin can be measured by GPC (Gel Permeation Chromatography, gel permeation chromatography).

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

  Such shell resin may be formed in the form of particles or in the form of a film on the surface of the core particle. The shell particles (particles containing shell resin) or the shell film (film containing shell resin) may further contain a colorant or an optional component (for example, a pigment dispersant, a wax, a charge control agent, etc.).

  The median diameter D50 when measured on a volume basis of the particle size distribution of shell particles contained in the shell dispersion liquid so that the median diameter D50 of the toner particles is in a desired range (hereinafter referred to as "median diameter D50 of shell particles" It is preferable to adjust) as appropriate. The median diameter D50 of the shell particles is preferably 0.0005 μm or more and 3 μm or less. The upper limit of the median diameter D50 of the shell particles is more preferably 2 μm, still more preferably 1 μm. The lower limit of the median diameter D50 of the shell particles is more preferably 0.01 μm, still more preferably 0.02 μm, and still more preferably 0.04 μm. For example, when it is desired to obtain toner particles having a median diameter D50 of 1 μm, the median diameter D50 of the shell particles is preferably 0.0005 to 0.3 μm, and more preferably 0.001 to 0.2 μm. is there. When it is desired to obtain toner particles having a median diameter D50 of 10 μm, the median diameter D50 of the shell particles is preferably 0.005 μm or more and 3 μm or less, more preferably 0.05 μm or more and 2 μm or less. The median diameter D50 of shell particles can be measured by the same method as the method of measuring the median diameter D50 of core particles.

<Colorant>
Preferably, the particle size of the colorant is 0.3 μm or less. If the particle size of the colorant is 0.3 μm or less, the dispersibility of the colorant can be enhanced, and thus the gloss of the image can be enhanced. This facilitates the realization of the desired color.

  As the colorant, conventionally known pigments and the like can be used without particular limitation, but it is preferable to use the following pigments from the viewpoints of cost, light resistance, colorability and the like. In terms of color constitution, these pigments are generally classified into black pigments, yellow pigments, magenta pigments and cyan pigments. Basically, colors other than black (color image) are toned by subtractive color mixing of yellow pigment, magenta pigment or cyan pigment. The pigments shown below may be used alone or, if necessary, two or more of the pigments shown below may be used in combination.

  The pigment (black pigment) contained in the black colorant may be, for example, carbon black such as furnace black, channel black, acetylene black, thermal black or lamp black, or may be biomass-derived carbon black or the like. It may be a magnetic powder such as magnetite or ferrite. A purple-black dye, nigrosine (azine compound) may be used alone or in combination. Examples of nigrosine include C.I. I. Solvent black 5 or C.I. I. It is preferable to use solvent black 7 or the like.

  The pigment (magenta pigment) contained in the magenta colorant is, for example, 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 or C.I. I. Pigment red 222 is preferable.

  The pigment (yellow pigment) contained in the yellow colorant is, for example, 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 or C.I. I. Pigment Yellow 185 is preferable.

  The pigment (cyan pigment) contained in the cyan colorant is, for example, 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 or C.I. I. Pigment green 7 etc. is preferable.

<Optional Component in Toner Particles (Pigment Dispersant)>
A pigment dispersant is mentioned as an example of the arbitrary components in toner particles. The pigment dispersant has an effect of uniformly dispersing a colorant (pigment) in toner particles, and is preferably a basic dispersant. Basic dispersants are those defined below. That is, 0.5 g of the pigment dispersant and 20 ml of distilled water are placed in a glass screw tube, and the glass screw tube is shaken and mixed for 30 minutes using a paint shaker. The obtained liquid is filtered, and the pH of the obtained filtrate is measured using a pH meter (product number "D-51" manufactured by HORIBA, Ltd.). A basic dispersant is used when the pH of the filtrate is greater than 7. When the pH of the filtrate is less than 7, it is referred to as an acidic dispersant.

  The type of basic dispersant is not particularly limited. The basic dispersant is, for example, an amine group, an amino group, an amido group, a pyrrolidone group, an imine group, an imino group, a urethane group, a quaternary ammonium group, an ammonium group, a pyridino group, a pyridinium group, an imidazolino group, or imidazolium It is preferable that it is a compound which has functional groups, such as group, in a molecule | numerator. In addition, as a dispersing agent, the so-called surfactant which has a hydrophilic part and a hydrophobic part in a molecule | numerator normally corresponds. However, the pigment dispersant is not limited to the surfactant, and various compounds can be used as the pigment dispersant, as long as it has the function of uniformly dispersing the colorant (pigment) in the toner particles.

  As a commercial item of the basic dispersant, for example, “Adispar PB-821” (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd., “Addasper PB-822” (trade name), or “Addasper PB-881” (trade name) And the like, and “Sol spars 28000” (trade name), “Sol spars 32000” (trade name), “Sol spars 32500” (trade name), “Sol spars 35100” (trade name) or Solspurs 37500 (trade name) and the like.

  As the pigment dispersant, it is more preferable to select one that does not dissolve in the insulating liquid. Taking this point into consideration, as a basic dispersant, “Adispar PB-821” (trade name), “Adispar PB-822” (trade name), or “Aisper PB-881” (trade name) manufactured by Ajinomoto Fine Techno Co., Ltd. It is more preferable to use a trade name) or the like. Although the detailed mechanism is unknown, the use of such pigment dispersants facilitates obtaining toner particles having a desired shape. As the pigment dispersant, any one of the above-mentioned dispersants may be used alone, or at least two of the above-mentioned dispersants may be used in combination.

  The pigment dispersant is preferably added in an amount of 1% by mass to 100% by mass, and more preferably 1% by mass to 40% by mass, based on the colorant (pigment). When the addition amount of the pigment dispersant is 1% by mass or more, the dispersibility of the colorant (pigment) can be secured, so that the necessary ID (image density) can be achieved, and the fixing strength can be secured. If the addition amount of the pigment dispersant is 100% by mass or less, the addition amount of the pigment dispersant can be prevented from being excessive, so that the excess of the pigment dispersant can be prevented from being dissolved in the insulating liquid. Thus, the chargeability of the toner particles or the fixing strength of the toner particles can be maintained in a good state.

<Insulating liquid>
The insulating liquid preferably has a resistance value that does not disturb the electrostatic latent image (about 10 ¹¹ Ω · cm to 10 ¹⁶ Ω · cm or less), and is preferably a solvent with low odor and toxicity. Generally as an insulating liquid, aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon, halogenated hydrocarbon or polysiloxane etc. are mentioned. In particular, the insulating liquid is preferably a normal paraffinic solvent or an isoparaffinic solvent from the viewpoint of low odor, low harmfulness, low cost and the like. More preferably, the insulating liquid is Moresco White (trade name, manufactured by Matsumura Sekiyu Co., Ltd.), Isopar (trade name, manufactured by Exxon Mobil), Shellsol (trade name, manufactured by Shell Chemicals Japan Ltd.), etc. IP solvent 1620, IP solvent 2028 or IP solvent 2835 (all are trade names, manufactured by Idemitsu Kosan Co., Ltd.) and the like.

[Production of liquid developer]
The method for producing the liquid developer according to the present embodiment is not particularly limited, and examples thereof include conventionally known techniques such as a granulation method and a grinding method. In order to obtain toner particles having a small diameter and sharp particle size distribution, it is preferable to employ a granulation method rather than a pulverization method. A highly meltable resin or a highly crystalline resin is soft even at normal temperature and difficult to be crushed. Therefore, in the pulverizing method, the particle size of the toner particles may not be able to be controlled to a desired particle size. However, in the granulation method, toner particles having a desired particle size can be obtained.

  In the granulation method, suspension polymerization method, emulsion polymerization method, fine particle aggregation method, a method of depositing a toner particle by adding a poor solvent to a resin solution, or a spray dry method, etc., from the difference in formation mechanism of toner particles. Is included.

  More preferably, the poor solvent is added to the resin solution to precipitate toner particles. In this method, first, the core resin is dissolved in a good solvent to obtain a solution for forming a core resin. After the core resin forming solution is mixed with an interfacial tension regulator (for example, a shell resin) in a poor solvent (the SP value is different from that of a good solvent), shear is applied to form droplets. Thereafter, the good solvent is evaporated to obtain a liquid developer containing toner particles. In this method, the particle size of the toner particles or the shape of the toner particles can be highly controlled by appropriately adjusting the way of applying shear, the interfacial tension difference, or the interfacial tension regulator (for example, shell resin). Thus, this method is suitable as a method for obtaining toner particles having a desired particle size distribution and a desired shape.

  When the core resin forming solution is mixed with the shell resin in the poor solvent, it is preferable to mix the core resin forming solution in a dispersion (shell dispersion) in which shell particles containing the shell resin are dispersed in the poor solvent. . For example, it is preferable to manufacture shell particles by any one of the following [1] to [7]. From the viewpoint of easiness of producing shell particles, it is preferable to produce shell particles by the method of [4], [6] or [7], and to produce shell particles by the method of [6] or [7] Is more preferred.

[1] The shell resin is pulverized dry using a known dry pulverizer such as a jet mill [2] The powder of shell resin is dispersed in an organic solvent, and a known wet disperser such as a bead mill or roll mill is used Wet pulverize [3] Spray a solution of shell resin with a spray drier etc. and dry it [4] Add a solution of poor solvent to the solution of shell resin or cool down to supersaturate shell resin and precipitate [5] A solution of shell resin is dispersed in water or an organic solvent [6] A precursor of shell resin is polymerized in water by emulsion polymerization, soap-free emulsion polymerization, seed polymerization, suspension polymerization, etc. [7] The precursor of the shell resin is polymerized by dispersion polymerization or the like in an organic solvent.

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following.
<Production Example 1> [Production of Amorphous Polyester Resin (A)]
In a reaction vessel equipped with a stirrer, heating / cooling device, and a thermometer, 728 parts by mass of propylene oxide 2 mol adduct of bisphenol A, 109 parts by mass of terephthalic acid, 163 parts by mass of isophthalic acid, and titanium dihydroxy bis (triethanolaminate) (Condensation catalyst) 2 parts by mass were added. The reaction was carried out at 180 ° C. under a nitrogen stream for 8 hours while removing water formed.

  Next, while gradually raising the temperature to 220 ° C., and also while removing the generated water, the reaction was performed for 4 hours under a nitrogen stream. Then, it was made to react under pressure reduction of 0.007-0.026MPa for 1 hour. 34 parts by mass of trimellitic anhydride was further added to the above reaction vessel, and reacted at 180 ° C. for 1 hour. Thus, an amorphous polyester resin (A) was obtained. It was 19 when the acid value of amorphous polyester resin (A) was calculated | required according to the above-mentioned method.

<Production Example 2> [Production of Amorphous Polyester Resin (B)]
Amorphous polyester resin (B) was obtained according to the method described in Production Example 1 except that the blending amount of trimellitic anhydride was changed to 45 parts by mass. When the acid value of the amorphous polyester resin (B) was determined according to the above-mentioned method, the acid value was 25.

<Production Example 3> [Production of Amorphous Polyester Resin (C)]
Amorphous polyester resin (C) was obtained according to the method described in Production Example 1 except that the content of trimellitic anhydride was changed to 64 parts by mass. When the acid value of the amorphous polyester resin (C) was determined according to the above-mentioned method, the acid value was 35.

<Production Example 4> [Production of Crystalline Polyester Resin (a)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 432 parts by mass of hexanediol, 568 parts by mass of sebacic acid and 2 parts by mass of titanium dihydroxybis (triethanolaminate) (condensation catalyst) were placed. The reaction was carried out at 180 ° C. under a nitrogen stream for 8 hours while removing water formed.

  Next, while gradually raising the temperature to 220 ° C., and also while removing the generated water, the reaction was performed for 4 hours under a nitrogen stream. Then, it was made to react under pressure reduction of 0.007-0.026MPa for 1 hour. Thus, a crystalline polyester resin (a) was obtained. It was 0 when the acid value of crystalline polyester resin (a) was calculated | required according to the above-mentioned method.

<Production Example 5> [Production of Crystalline Polyester Resin (b)]
In a reaction vessel equipped with a stirrer, a heating / cooling device and a thermometer, 432 parts by mass of hexanediol, 568 parts by mass of sebacic acid and 2 parts by mass of titanium dihydroxybis (triethanolaminate) (condensation catalyst) were placed. The reaction was carried out at 180 ° C. under a nitrogen stream for 8 hours while removing water formed.

  Next, while gradually raising the temperature to 220 ° C., and also while removing the generated water, the reaction was performed for 4 hours under a nitrogen stream. Then, it was made to react under pressure reduction of 0.007-0.026MPa for 1 hour. 9 mass parts of trimellitic anhydrides were further added to the said reaction container, and it was made to react at 180 degreeC for 1 hour. Thus, a crystalline polyester resin (b) was obtained. It was 5 when the acid value of crystalline polyester resin (b) was calculated | required according to the above-mentioned method.

<Production Example 6> [Production of Crystalline Polyester Resin (c)]
A crystalline polyester resin (c) was obtained according to the method described in Production Example 5, except that the content of trimellitic anhydride was changed to 35 parts by mass. It was 20 when the acid value of crystalline polyester resin (c) was calculated | required according to the above-mentioned method.

<Production Example 7> [Production of Crystalline Polyester Resin (d)]
A crystalline polyester resin (d) was obtained according to the method described in Production Example 5 except that the blending amount of trimellitic anhydride was changed to 74 parts by mass. It was 40 when the acid value of crystalline polyester resin (d) was calculated | required according to the above-mentioned method.

<Production Example 8> [Production of Solution (1) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (C), 80 parts by mass of the crystalline polyester resin (b) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thereby, the solution (1) for core resin formation was obtained. It was 40 mass% when solid content concentration of the obtained solution (1) for core resin formation was measured. Further, the acid value of the solid content (corresponding to the acid value of the core resin, hereinafter the same) was 29.

<Production Example 9> [Production of Core Resin Forming Solution (2)]
380 parts by mass of the amorphous polyester resin (C), 20 parts by mass of the crystalline polyester resin (b) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin-forming solution (2) was obtained. It was 40 mass%, when solid content concentration of the obtained solution (2) for core resin formation was measured. Moreover, the acid value of solid content was 34.

<Production Example 10> [Production of Solution (3) for Forming Core Resin]
280 parts by mass of the amorphous polyester resin (C), 120 parts by mass of the crystalline polyester resin (b) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin forming solution (3) was obtained. It was 40 mass% when solid content concentration of the obtained solution (3) for core resin formation was measured. Moreover, the acid value of solid content was 26.

<Production Example 11> [Production of Solution (4) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (C), 80 parts by mass of the crystalline polyester resin (c) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thereby, the solution (4) for core resin formation was obtained. It was 40 mass%, when solid content concentration of the obtained solution (4) for core resin formation was measured. Moreover, the acid value of solid content was 32.

<Production Example 12> [Production of Solution (5) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (B), 80 parts by mass of the crystalline polyester resin (a) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thereby, the solution (5) for core resin formation was obtained. It was 40 mass% when solid content concentration of the obtained solution (5) for core resin formation was measured. Moreover, the acid value of solid content was 20.

<Production Example 13> [Production of Solution (6) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (A), 80 parts by mass of the crystalline polyester resin (d) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin forming solution (6) was obtained. It was 40 mass%, when solid content concentration of the obtained solution (6) for core resin formation was measured. Moreover, the acid value of solid content was 23.

<Production Example 14> [Production of Solution (7) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (A), 80 parts by mass of the crystalline polyester resin (a) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin-forming solution (7) was obtained. It was 40 mass% when solid content concentration of the obtained solution (7) for core resin formation was measured. Moreover, the acid value of solid content was 15.

<Production Example 15> [Production of Solution (8) for Forming Core Resin]
400 parts by mass of the amorphous polyester resin (C) and 600 parts by mass of acetone were placed in a beaker and stirred, and the amorphous polyester resin (C) was uniformly dissolved in acetone. Thus, a core resin forming solution (8) was obtained. It was 40 mass%, when solid content concentration of the obtained solution (8) for core resin formation was measured. Moreover, the acid value of solid content was 35.

<Production Example 16> [Production of Solution (9) for Forming Core Resin]
240 parts by mass of the amorphous polyester resin (C), 160 parts by mass of the crystalline polyester resin (b) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin forming solution (9) was obtained. It was 40 mass%, when solid content concentration of the obtained solution (9) for core resin formation was measured. Moreover, the acid value of solid content was 23.

<Production Example 17> [Production of Solution (10) for Forming Core Resin]
320 parts by mass of the amorphous polyester resin (B), 80 parts by mass of the crystalline polyester resin (c) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin-forming solution (10) was obtained. It was 40 mass% when solid content concentration of the obtained solution (10) for core resin formation was measured. Moreover, the acid value of solid content was 24.

<Production Example 18> [Production of Solution (11) for Forming Core Resin]
360 parts by mass of the amorphous polyester resin (C), 40 parts by mass of the crystalline polyester resin (b) and 600 parts by mass of acetone were placed in a beaker and stirred, and these polyester resins were uniformly dissolved in acetone. Thus, a core resin forming solution (11) was obtained. It was 40 mass% when solid content concentration of obtained solution (11) for core resin formation was measured. Moreover, the acid value of solid content was 32.

<Production Example 19> [Production of Polyester Resin (α)]
In a reaction vessel equipped with a stirrer, a heater / cooler, a thermometer, a cooling pipe and a nitrogen introducing pipe, 338 parts by mass of adipic acid, 162 parts by mass of ethylene glycol and 1 mass of titanium dihydroxy bis (triethanol aminate) (condensation catalyst) Department and put. The reaction was carried out at 180 ° C. under a nitrogen stream for 8 hours while removing water formed.

  Next, while gradually raising the temperature to 220 ° C., and also while removing the generated water, the reaction was performed for 4 hours under a nitrogen stream. The reaction was conducted for 1 hour under a reduced pressure of 0.007 to 0.026 MPa. Thus, a polyester resin (α) was obtained. The Mn of the polyester resin (α) was determined in accordance with the above-described method and found to be 3500.

<Production Example 20> [Production of Monomer Having Polymerizable Double Bond]
100 parts by mass of THF (tetrahydrofuran) and 192 parts by mass of the polyester resin (α) obtained in Production Example 19 were put in a reaction vessel equipped with a stirrer, heating / cooling device, thermometer, cooling pipe and nitrogen introducing pipe. . After replacing the gas phase of the reaction vessel with nitrogen, the polyester resin (α) was dissolved at 65 ° C. Next, in the above reaction vessel, 8.5 parts by weight of a monomer containing isocyanate group (trade name "Kalenz MOI" manufactured by Showa Denko KK) and a catalyst (trade name "Neostan U-600" manufactured by Nitto Kasei Corp.) 0 Further, 2 parts by mass was added and reacted at 70 ° C. for 4 hours. Thus, a monomer having a polymerizable double bond was obtained.

<Production Example 21> [Production of Dispersion for Shell]
In a glass beaker, 45 parts by mass of n-octyl methacrylate, 15 parts by mass of 2-decyl tetradecyl methacrylate, 15 parts by mass of methacrylic acid, 25 parts by mass of the monomer obtained in Production Example 20 and azobismethoxydimethylvaleronitrile 0 1 part by mass was added and mixed by stirring at 20 ° C. Thus, a monomer solution was obtained.

  A reaction vessel equipped with a stirring device, a heating and cooling device, a thermometer, a dropping funnel, a solvent removal device, and a nitrogen introduction pipe was prepared. 100 parts by mass of THF was placed in the reaction vessel, and the above monomer solution was placed in the dropping funnel. After replacing the gas phase of the reaction vessel with nitrogen, the monomer solution was added dropwise to THF over 1 hour at 70 ° C. under seal. Three hours after the completion of the dropping of the monomer solution, a mixture of 0.05 parts by mass of azobismethoxydimethylvaleronitrile and 5 parts by mass of THF was added to the monomer solution. After reacting at 70 ° C. for 3 hours, it was cooled to room temperature. Thus, a copolymer solution was obtained.

  After dropping 200 parts by mass of the obtained copolymer solution into 300 parts by mass of an insulating liquid (trade name "IP Solvent 2028" manufactured by Idemitsu Kosan Co., Ltd.) under stirring, the mixture is then cooled at 40 ° C under a reduced pressure of 0.039 MPa. The THF was removed. Thus, a dispersion for shell was obtained. It was 40000 when Mn of shell resin contained in the dispersion liquid for shells was calculated | required according to the above-mentioned method.

<Production Example 22> [Production of Dispersion of Colorant]
In a beaker, 25 parts by mass of copper phthalocyanine (trade name “Fastogen Blue FDB-14” manufactured by DIC Corporation) (coloring agent (pigment)) and a pigment dispersant (trade name “Ajispar PB-821 manufactured by Ajinomoto Fine Techno Co., Ltd. ) 4 parts by mass of acetone and 75 parts by mass of acetone were added and stirred to disperse copper phthalocyanine uniformly. Copper phthalocyanine was finely dispersed using a bead mill to obtain a dispersion of colorant. The median diameter D50 of copper phthalocyanine in the colorant dispersion was 0.2 μm.

Example 1 Production of Liquid Developer (1)
In a beaker, 410 parts by mass of the solution (1) for forming a core resin and 190 parts by mass of a dispersion of a colorant were placed. The resulting solution was stirred at 16000 rpm at 25 ° C. using a TK autohomomixer (manufactured by Primix, Inc.). In this way, a resin solution in which the colorant was uniformly dispersed was obtained.

  In another beaker, 670 parts by mass of an insulating liquid (trade name "IP Solvent 2028" manufactured by Idemitsu Kosan Co., Ltd.) and 60 parts by mass of a dispersion for shells were placed. While stirring the obtained solution at 25 ° C. using Creamix (manufactured by M. Technique Co., Ltd.) at 20000 rpm, 600 parts by mass of the above resin solution was added. Then, it stirred for 2 minutes.

  The resulting mixture was placed in a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a solvent removing device, and the temperature was raised to 35 ° C. Acetone was removed from the mixture at the same temperature and under a reduced pressure of 0.039 MPa until the acetone concentration was below 0.5 wt%. Thus, a liquid developer (1) was obtained. In the liquid developer (1), the content of the colorant (pigment) in the toner particles was 20% by mass, and the content of the toner particles in the liquid developer was 24% by mass.

Example 2 Production of Liquid Developer (2)
A liquid developer (2) was obtained according to the method described in Example 1 except that the core resin forming solution (2) was used instead of the core resin forming solution (1).

Example 3 Production of Liquid Developer (3)
A liquid developer (3) was obtained according to the method described in Example 1 except that the core resin forming solution (3) was used instead of the core resin forming solution (1).

Example 4 Production of Liquid Developer (4)
A liquid developer (4) was obtained according to the method described in Example 1 except that the core resin forming solution (4) was used instead of the core resin forming solution (1).

Example 5 Production of Liquid Developer (5)
A liquid developer (5) was obtained according to the method described in Example 1 except that the core resin forming solution (5) was used instead of the core resin forming solution (1).

Example 6 Production of Liquid Developer (6)
A liquid developer (6) was obtained according to the method described in Example 1 except that the core resin forming solution (6) was used instead of the core resin forming solution (1).

Example 7 Production of Liquid Developer (7)
A liquid developer (7) was obtained according to the method described in Example 1 except that the core resin forming solution (7) was used instead of the core resin forming solution (1).

<Comparative Example 1> [Production of Liquid Developer (8)]
A liquid developer (8) was obtained according to the method described in Example 1 except that the core resin forming solution (8) was used instead of the core resin forming solution (1).

<Comparative Example 2> [Production of Liquid Developer (9)]
A liquid developer (9) was obtained according to the method described in Example 1 except that the core resin forming solution (9) was used instead of the core resin forming solution (1).

<Comparative Example 3> [Production of Liquid Developer (10)]
A liquid developer (10) was obtained according to the method described in Example 1 except that the core resin forming solution (10) was used instead of the core resin forming solution (1).

<Comparative Example 4> [Production of Liquid Developer (11)]
The core resin forming solution (11) was used instead of the core resin forming solution (1), and “60 parts by mass of the dispersion liquid for shell” was added to “Dispersant (trade name (Sol Sparse S11200) manufactured by Lubrizol Corporation) (fat The liquid developer (11) was obtained according to the method described in Example 1 except that the content of the group hydrocarbon solvent was changed to 120 parts by mass (containing 50% by mass).

<Evaluation of aggregation resistance>
The aggregation resistance of the toner particles was examined using the apparatus shown in FIG. First, the median diameter D50 (the median diameter D50 before rotation) of toner particles was determined according to the method described below.

  The median diameter D50 of toner particles in a liquid developer was measured using a flow type particle image analyzer (trade name "FPIA-3000" manufactured by Sysmex Corporation). As the flow solvent, the same as the insulating liquid, "IP Solvent 2028" (manufactured by Idemitsu Kosan Co., Ltd.) was used under the trade name. Next, 50 mg of toner particles were added to a flow solvent (20 g) containing 30 mg of a dispersant (trade name "Sol spars S 13940" manufactured by Nippon Lubrizol Co., Ltd.). The suspension obtained in this manner was subjected to dispersion treatment for about 5 minutes using an ultrasonic disperser (trade name “Ultrasonic Cleaner model VS-150” manufactured by Well Clear). The median diameter D50 of the toner particles (the median diameter D50 before rotation) was determined using the sample thus obtained.

Next, 200 g of the liquid developer 21 was placed in the developing tank 1, and the first roller 3 and the second roller 5 rotating in the opposite direction were disposed as shown in FIG. In the apparatus shown in FIG. 1, the liquid developer 21 is drawn up by the first roller 3 and sent to the second roller 5. After rotating the first roller 3 and the second roller 5 for 3 hours, the median diameter D50 of the toner particles (the median diameter D50 after rotation) was determined. The change rate of the median diameter D50 of toner particles was determined using the following formula. The results are shown in Table 1.
(Rate of change of median diameter D50 of toner particles) = (median diameter D50 after rotation) / (median diameter D50 before rotation).

  In Table 1, when the rate of change of the median diameter D50 of toner particles is less than 1.2, it is described as “A1”, and the rate of change of the median diameter D50 of toner particles is 1.2 or more and less than 1.4. In the case where the change rate of the median diameter D50 of the toner particles is 1.4 or more and less than 1.6 in the case of "B1," the change rate of the median diameter D50 of the toner particles is 1.6 or more When there is, it is written as "D1". It can be said that the toner particles are more excellent in the aggregation resistance as the rate of change of the median diameter D50 of the toner particles is lower.

<Evaluation of low temperature fixability>
First, an image was formed on a recording medium (trade name “OK Top Coat Plus” (128 g / m ² ) manufactured by Oji Paper Co., Ltd.) according to the method described later. The adhesion amount of toner particles to the recording medium was 3 g / m ² . The unfixed image was fixed on the recording medium using a heat roller fixing device. Here, the set temperature of the roller was 100 ° C., the fixing NIP time was 30 msec, and the temperature of the recording medium immediately after passing through the heat roller fixing device was 80 ° C.

  Next, a tape (trade name "Scotch Mending Tape" manufactured by Sumitomo 3M Ltd.) was attached to the measurement target portion of the recording medium on which the image was fixed, and then the tape was peeled off. Next, using a reflection densitometer (trade name “X-Rite model 404” manufactured by X-Rite Co., Ltd.), the image density (ID) of the image peeled off on the tape was determined. The results are shown in Table 1.

  In Table 1, "A2" is described when the image density is less than 0.1, and "B2" is described when the image density is 0.1 or more and less than 0.15, and the image density is 0.15. When it is above, it describes as "C2". As the image density is lower, the fixed image is less likely to be peeled off by the tape, so that it can be said that the fixability of the toner particles is excellent. In this embodiment, the set temperature of the roller at the time of fixing is 100 ° C., and the temperature of the recording medium immediately after passing through the heat roller fixing device is 80 ° C. (Low temperature fixability is excellent).

<Formation of image>
An image was formed using the image forming apparatus shown in FIG. The configuration of the image forming apparatus shown in FIG. 2 is shown below. The liquid developer 21 is drawn up from inside the developing tank 22 by the anilox roller 23. The liquid developer 21 on the anilox roller 23 is sent to the leveling roller 25 and the liquid developer 21 (excess liquid developer 21) not sent to the leveling roller 25 is scraped off by the anilox regulating blade 24. .

  The liquid developer 21 on the leveling roller 25 is sent to the developing roller 26. The liquid developer 21 on the developing roller 26 is charged by the developing charger 28 and developed on the photosensitive member 29, and the excess liquid developer is scraped off by the developing cleaning blade 27. In detail, the surface of the photosensitive member 29 is uniformly charged by the charging unit 30, and the exposure unit 31 disposed around the photosensitive member 29 receives light based on predetermined image information as the surface of the photosensitive member 29. Irradiate. Thereby, an electrostatic latent image based on predetermined image information is formed on the surface of the photosensitive member 29. A toner image is formed on the photosensitive member 29 by developing the formed electrostatic latent image. The excess liquid developer on the photosensitive member 29 is scraped off by the cleaning blade 32.

  The toner image formed on the photosensitive member 29 is primarily transferred to the intermediate transfer member 33 at the primary transfer portion 37, and the liquid developer transferred to the intermediate transfer member 33 is secondarily transferred to the recording medium 40 at the secondary transfer portion 38. Be done. The liquid developer remaining on the intermediate transfer member 33 without being secondarily transferred is scraped off by the intermediate transfer member cleaning unit 34. The recording medium 40 to which the liquid developer has been secondarily transferred is conveyed to a fixing unit (not shown), and the liquid developer is fixed to the recording medium 40 in the fixing unit.

  In the present embodiment, the surface of the photosensitive member 29 is positively charged by the charging unit 30, the potential of the intermediate transfer member 33 is −400 V, and the potential of the secondary transfer roller 35 is −1200 V. The conveyance speed of the recording medium 40 was 400 mm / s.

<Result>
The results are shown in Table 1.

In Table 1, “blending ratio (mass%) ^{* 11} ” is non-crystalline with respect to the total (mass of core resin) of the blending amount (mass) of non-crystalline polyester resin and the blending amount (mass) of crystalline polyester resin Means the proportion of the blending amount (mass) of the water-soluble polyester resin.

The “blending ratio (mass%) ^{* 12} ” is the ratio of the blending amount (mass) of the crystalline polyester resin to the total of the blending amount (mass) of the amorphous polyester resin and the blending amount (mass) of the crystalline polyester resin Means

“ΔAV ^{* 13} ” is a numerical value calculated using the following equation.
ΔAV ^{* 13} = (acid value of crystalline polyester resin)-(acid value of amorphous polyester resin)
"Core / shell ^{* 14} " means that the toner particles have a core / shell structure. "Non-core / shell ^{* 15} " means that the toner particles do not have a core / shell structure.

<Discussion>
In Comparative Example 1, the low temperature fixability was lower than in Examples 1 to 7. Therefore, it is preferable that the core resin contains 5% by mass or more of the crystalline polyester resin.

  In Comparative Example 2, the aggregation resistance of the toner particles was reduced as compared with Examples 1 to 7. Therefore, it is preferable that the core resin contains 70% by mass or more of amorphous polyester resin.

In Comparative Example 3, the aggregation resistance of the toner particles was reduced as compared with Examples 1 to 7. Therefore, it is preferable that the difference in acid value (absolute value of ΔAV ^{* 13} ) is 15 mg KOH / g or more.

  In Comparative Example 4, the aggregation resistance of the toner particles was reduced as compared to Examples 1 to 7. Therefore, it is preferable that the toner particles have a core / shell structure.

  In Examples 1, 2 and 5 to 7, the aggregation resistance of the toner particles is further enhanced as compared with Example 3. Therefore, it is more preferable that the core resin contains less than 30% by mass of the crystalline polyester resin.

In Examples 1, 2 and 5 to 7, the aggregation resistance of the toner particles is further enhanced as compared with Example 4. Therefore, it is more preferable that the difference in acid value (absolute value of ΔAV ^{* 13} ) is larger than 15 mg KOH / g.

In Example 6, as compared with the other examples except Example 6, the aggregation resistance of the toner particles was further enhanced. Therefore, it can be said that the acid value of the crystalline polyester resin is more preferably larger than that of the amorphous polyester resin (ΔAV ^{* 13} > 0).

  In Examples 1 and 3 to 6, the low temperature fixability was further improved as compared with Example 2. Therefore, it is more preferable that the core resin contains the crystalline polyester resin in an amount of more than 5% by mass.

  In Examples 1 and 3 to 6, the low temperature fixability was further improved as compared with Example 7. Therefore, it is more preferable that the acid value of the core resin is 20 mg KOH / g or more.

  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 indicated not by the above description but by the claims, and is intended to include all the modifications within the meaning and scope equivalent to the claims.

  DESCRIPTION OF SYMBOLS 1 developing tank, 3 1st roller, 5 2nd roller, 21 liquid developer, 22 developing tank, 23 anilox roller, 24 anilox regulating blade, 25 straightening roller, 26 developing roller, 27 developing cleaning blade, 28 developing charger, 29 photosensitive member, 30 charging unit, 31 exposure unit, 32 cleaning blade, 33 intermediate transfer member, 34 intermediate transfer member cleaning unit, 35 secondary transfer roller, 37 primary transfer unit, 38 secondary transfer unit, 40 recording medium.

Claims (3)

A liquid developer comprising: an insulating liquid; and toner particles dispersed in the insulating liquid,
The toner particles have a core / shell structure,
The core / shell structure has a core particle containing a core resin, and a shell resin which is provided on at least a part of the surface of the core particle and is a resin different from the core resin,
The core resin contains 5% by mass or more and 30% by mass or less of a crystalline polyester resin, and 70% by mass or more and 95% by mass or less of an amorphous polyester resin,
The difference between the acid value of the crystalline polyester resin and the acid value of the non-crystalline polyester resin is 15 mg KOH / g to 100 mg KOH / g,
The shell resin is one of vinyl resin (excluding Antaron V-216, Antaron V-220 and Antaron W-660) , epoxy resin, silicone resin, phenol resin, ionomer resin, polycarbonate resin, and polyester resin. Liquid developer consisting of resin of a kind or more.   The liquid developer according to claim 1, wherein the acid value of the core resin is 20 mg KOH / g or more and 100 mg KOH / g or less.   The liquid developer according to claim 1, wherein an acid value of the crystalline polyester resin is larger than an acid value of the non-crystalline polyester resin.

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