JP6808464B2 - Liquid developer - Google Patents

Description

The present invention relates to, for example, a liquid developer used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like, and a method for producing the same.

Examples of the electrophotographic developer include a dry developer that uses a toner component made of a material containing a colorant and a binder resin in a dry state, and a liquid developer in which the toner component is dispersed in an insulating liquid.

In the liquid developer, the toner particles are dispersed in the oil in the insulating liquid, so that the particle size can be reduced as compared with the dry developer. Therefore, it is possible to obtain a high-quality printed matter that surpasses offset printing, and is suitable for commercial printing applications. Further, in recent years, there is an increasing demand for high speed, so that the viscosity of the liquid developer is required to be reduced. Further, there is a demand for a liquid developer capable of melting and fixing toner particles with a small amount of heat, that is, a liquid developer having excellent low-temperature fixability.

Patent Document 1 includes an amine-functionalized polymer grafted with a stabilizing group for the purpose of providing a stable liquid toner dispersion that does not disturb the melting process and does not cause significant caking. A superdispersant, including a graft copolymer with a fixing group, is included, the fixing group is immobilized on the surface of the marking particles, the first stabilizing group and the second stabilizing group are grafted to the fixing group, and the second A liquid toner dispersion characterized in that the stabilizing group of 1 is a fatty acid compound and the stabilizing group of 2 is a polyolefin is disclosed.

Patent Document 2 states that the color reproducibility is excellent, the electrophoretic property, chargeability, and dispersion state of the toner particles in the liquid developer are stable even when the number of prints and the print area increase, and the image density is stable. A dispersant for the purpose of providing a liquid developer in which fog does not occur on a white background, segregation of dispersant components in the liquid developer does not occur, and the developer composition does not change for a long period of time. However, a liquid developer characterized by containing an imide succinate compound and a fluorine-containing silane compound is disclosed.

In Patent Document 3, for the purpose of providing a method for producing a liquid developer having excellent dispersion stability and fixability of toner particles, Step 1: Resin and pigment are melt-kneaded and pulverized to obtain toner particles. Step, Step 2: Toner particles obtained in Step 1 are dispersed in an insulating liquid in the presence of a basic dispersant to obtain a toner particle dispersion liquid, and Step 3: Toner particles obtained in Step 2 An amide compound obtained by a reaction of polyethyleneimine with polyester (D) obtained by self-condensation of 12-hydroxystearic acid, which comprises a step of wet-grinding the dispersion to obtain a liquid developer. A method for producing a liquid developer, which is characterized by the above, is disclosed.

Patent Document 4 describes a binder resin for a wet developer, which is excellent in both wet grindability and non-contact fixability of toner particles, a toner particle containing the binder resin, and a wet developer containing the toner particles. A polyester-containing binder resin obtained by polycondensing an alcohol component and a carboxylic acid component containing a trivalent or higher valent carboxylic acid compound for the purpose of providing the above-mentioned trivalent or higher. A binder resin for a wet developing agent is disclosed, wherein the content of the polyvalent carboxylic acid compound in the carboxylic acid component is 40 to 100 mol%, and the number average molecular weight of the polyester is 400 to 2000.

Japanese Unexamined Patent Publication No. 2015-135475 Japanese Unexamined Patent Publication No. 2011-27845 Japanese Unexamined Patent Publication No. 2014-142624 Japanese Unexamined Patent Publication No. 2011-242457

In order to improve the low temperature fixability of the liquid developer, it is necessary for the toner particles to rapidly aggregate due to the heat during fixing. On the other hand, when the speed is increased, a large stress is applied near the blade in the printer and the temperature is locally heated to about 50 ° C. In that state, it is required to maintain the storage stability.

The present invention relates to a liquid developer having low viscosity, excellent storage stability, and excellent toner cohesiveness when heated at a high temperature, and a method for producing the same.

The present invention
[1] A liquid developer containing a binder resin containing a polyester resin, toner particles containing a colorant, a dispersant, and an insulating liquid, wherein the polyester resin contains an alcohol component and 100 mol of the alcohol component. It is a polycondensate with a carboxylic acid component containing 40 mol or more of a trivalent or more carboxylic acid compound, and the dispersant is a hydrocarbon having a molecular weight of 250 or less and a hydrocarbon having 16 or more carbon atoms. A liquid developer containing a reaction product with a hydrocarbon group-containing compound having a number average molecular weight of 500 or more, which is one or more selected from hydrogen and a polyester having a reactive functional group, and [2] the above [1]. This is a method for producing a liquid developer of
Step 1: A step of melt-kneading a binder resin containing a polyester resin and a colorant and pulverizing them to obtain toner particles.
Step 2: A step of mixing the toner particles obtained in Step 1 and a dispersant and dispersing them in an insulating liquid to obtain a toner particle dispersion liquid, and a step 3: Wetting the toner particle dispersion liquid obtained in Step 2. The present invention relates to a method for producing a liquid developer, which comprises a step of pulverizing to obtain a liquid developer.

The liquid developer of the present invention has the effects of low viscosity, excellent storage stability, and excellent toner cohesiveness when heated at high temperature. Further, the liquid developer of the present invention also has an effect that the toner particles have a small particle size.

The liquid developer of the present invention is a reaction of a polyester resin obtained by using a carboxylic acid compound having a valence of 3 or more as a binder resin with a polyalkyleneimine having a predetermined molecular weight as a dispersant and a hydrocarbon group-containing compound. Each of them contains a substance, and has low viscosity, excellent storage stability, and excellent toner cohesiveness when heated at a high temperature.

The reason for achieving such an effect is not clear, but it is considered as follows.
Since a carboxylic acid compound having a trivalent or higher valence such as trimellitic acid has high acidity, it has a strong interaction with a basic dispersant and easily adsorbs the dispersant. Therefore, it is excellent in storage stability. On the other hand, by using a dispersant containing a low molecular weight polyalkyleneimine, the adsorption points of the dispersant and the toner particles are reduced, so that the dispersant is easily desorbed by thermal motion during high temperature heating. Therefore, it is considered that the toner particles have excellent heat cohesiveness at high temperatures.

The liquid developer of the present invention contains toner particles, a dispersant, and an insulating liquid.

The toner particles contain a binder resin containing a polyester resin and a colorant.

Examples of the polyester resin include a polyester resin, a composite resin containing a polyester resin and another resin such as a styrene resin, and the like.

In the present invention, the polyester resin is preferably a polycondensate of an alcohol component containing a divalent or higher alcohol and a carboxylic acid component containing a divalent or higher carboxylic acid compound.

Examples of the divalent alcohol include an aliphatic diol having 2 or more and 20 or less carbon atoms, preferably 2 or more and 15 or less carbon atoms, and the formula (I):

(In the formula, RO and OR are oxyalkylene groups, R is ethylene and / or propylene group, x and y indicate the average number of moles of alkylene oxide added, which are positive numbers, respectively, of x and y. The value of the sum is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, still more preferably 4 or less).
Examples thereof include an alkylene oxide adduct of bisphenol A represented by. Specific examples of diols having 2 or more and 20 or less carbon atoms include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, and hydrogen. Examples thereof include added bisphenol A.

As the alcohol component, the pulverizability of the toner is improved to obtain toner particles having a small particle size, the low temperature fixability of the toner is improved, and the dispersion stability of the toner particles is improved to improve the storage stability. From the viewpoint, 1,2-propanediol or an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable, and 1,2-propanediol is more preferable from the viewpoint of storage stability. Further, from the viewpoint of pulverizability, the alkylene oxide adduct of bisphenol A represented by the formula (I) is more preferable. The content of the alkylene oxide adduct of 1,2-propanediol or bisphenol A represented by the formula (I) is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 in the alcohol component. It is mol% or more, more preferably 95 mol% or more, still more preferably 100 mol%. When 1,2-propanediol and an alkylene oxide adduct of bisphenol A represented by the formula (I) are used in combination, the total content of both is preferably within the above range.

Examples of the trihydric or higher alcohol include trihydric or higher alcohols having 3 or more and 20 or less carbon atoms, preferably 3 or more and 10 or less carbon atoms. Specific examples thereof include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, trimethylolpropane and the like.

The carboxylic acid component includes a carboxylic acid compound having a valence of 3 or more. Examples of the trivalent or higher carboxylic acid compound include 4 or more and 20 or less carbon atoms, preferably 6 or more and 20 or less carbon atoms, more preferably 7 or more and 15 or less carbon atoms, and further preferably 8 or more and 12 or less carbon atoms. Preferred examples thereof include trivalent or higher carboxylic acids having 9 or more and 10 or less carbon atoms, anhydrides thereof, or derivatives such as alkyl esters having 1 or more and 3 or less carbon atoms in the alkyl group. Specific examples thereof include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid), and acid anhydrides thereof.

The content of the trivalent or higher carboxylic acid compound is 40 mol or more, preferably 50 mol or more, with respect to 100 mol of the alcohol component, from the viewpoint of storage stability, and from the viewpoint of improving the chargeability of the toner. Therefore, it is preferably 80 mol or less, more preferably 60 mol or less.

Examples of the divalent carboxylic acid compound include dicarboxylic acids having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 3 to 10 carbon atoms, anhydrides thereof, or alkyl groups. Examples thereof include derivatives such as alkyl esters having 1 or more and 3 or less carbon atoms. Specifically, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, alkyl groups or carbons having 1 to 20 carbon atoms. Examples thereof include aliphatic dicarboxylic acids such as succinic acid substituted with an alkenyl group having a number of 2 or more and 20 or less.

As the divalent carboxylic acid compound, terephthalic acid or fumaric acid is preferable, and fumaric acid is preferable from the viewpoint of improving the low-temperature fixability of the toner and improving the dispersion stability of the toner particles to improve the storage stability. More preferred.

The content of the divalent carboxylic acid compound is preferably 3 mol or more, more preferably 5 mol, from the viewpoint of improving the pulverizability of the toner and obtaining toner particles having a small particle size with respect to 100 mol of the alcohol component. The above is more preferably 7 mol or more, and from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, it is preferably 70 mol or less, more preferably 60 mol or less, still more preferably 50 mol. It is as follows.

The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound as appropriate from the viewpoint of adjusting the molecular weight and softening point of the polyester resin.

The equivalent ratio (COOH group / OH group) of the carboxylic acid component and the alcohol component in the polyester resin is preferably 0.6 or more, more preferably 0.7 or more, still more preferably 0.75 or more from the viewpoint of adjusting the softening point of the polyester resin. Yes, and preferably 1.1 or less.

The polyester resin has, for example, an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and if necessary, in the presence of an esterification co-catalyst, a polymerization inhibitor, etc., at 130 ° C. It can be produced by polycondensation at a temperature of 250 ° C. or higher, preferably 170 ° C. or higher and 240 ° C. or lower.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin (II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropyrate bistriethanolaminate, and tin compounds are preferable. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 1.0 part by mass or less. Examples of the esterification co-catalyst include gallic acid and the like. The amount of the esterification co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. More preferably, it is 0.1 parts by mass or less. Examples of the polymerization inhibitor include t-butylcatechol and the like. The amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. It is preferably 0.1 parts by mass or less.

In the present invention, the polyester resin may be a polyester resin modified to such an extent that its characteristics are not substantially impaired. Examples of the modified polyester resin include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636 and the like. Examples of the modified polyester resin include a modified polyester resin, and among the modified polyester resins, a urethane-modified polyester resin obtained by urethane-extending the polyester resin with a polyisocyanate compound is preferable.

The softening point of the polyester resin is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and improves the low-temperature fixability of the toner from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint of the temperature, the temperature is preferably 130 ° C. or lower, more preferably 120 ° C. or lower.

The glass transition temperature of the polyester resin is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and improves low-temperature fixability, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint, it is preferably 80 ° C. or lower, more preferably 75 ° C. or lower.

The acid value of the polyester resin is preferably 40 mgKOH / g or more, more preferably 50 mgKOH / g, from the viewpoint of reducing the viscosity of the liquid developer and improving the dispersion stability of the toner particles to improve the storage stability. It is preferably 100 mgKOH / g or less, more preferably 80 mgKOH / g or less, from the viewpoint of improving the chargeability of the toner and improving the dispersion stability of the toner particles to improve the storage stability. Is. The acid value of the polyester resin can be adjusted by changing the equivalent ratio of the carboxylic acid component and the alcohol component, changing the reaction time during resin production, or changing the content of the carboxylic acid compound having a valence of 3 or more. Can be adjusted.

The content of the polyester resin is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 100% by mass, that is, only the polyester resin is used in the binder resin. However, a resin other than the polyester resin may be contained as long as the effect of the present invention is not impaired. Examples of resins other than polyester-based resins include polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, and styrene-maleic acid copolymer. , Styrene-acrylic acid ester copolymer, styrene-based resin, epoxy-based resin, rosin-modified maleic acid resin, which is a copolymer or copolymer containing styrene or a styrene-substituted product such as a styrene-methacrylic acid ester copolymer, One or more selected from resins such as polyethylene-based resin, polypropylene-based resin, polyurethane-based resin, silicone-based resin, phenol-based resin, aliphatic or alicyclic hydrocarbon resin can be mentioned.

As the colorant, dyes, pigments and the like used as colorants for toner can be used. For example, carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmin 6B, isoindoline, disazoero, etc. .. In the present invention, the toner particles may be either black toner or color toner.

From the viewpoint of improving the image density, the content of the colorant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more with respect to 100 parts by mass of the binder resin. Then, from the viewpoint of improving the pulverizability of the toner to reduce the particle size, improving the low-temperature fixability, and improving the dispersion stability of the toner particles to improve the storage stability, 100 masses of the binder resin It is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, still more preferably 30 parts by mass or less.

As a method for producing the toner particles, a method obtained by melt-kneading a toner raw material containing a binder resin and a colorant and crushing the obtained melt-kneaded product, preferably wet crushing, a water-based binder resin dispersion liquid and an aqueous system Examples thereof include a method of mixing the colorant dispersion liquid and combining the binder resin particles and the colorant particles, and a method of stirring the water-based binder resin dispersion liquid and the colorant at high speed. From the viewpoint of improving developability and fixability, a method of melt-kneading the toner raw material and then pulverizing, preferably wet pulverizing is preferable.

First, it is preferable that the toner raw material containing the binder resin, the colorant, the additive used if necessary, and the like is mixed in advance with a mixer such as a Henschel mixer, a super mixer, or a ball mill, and then supplied to the kneader. A Henschel mixer is more preferable from the viewpoint of improving the dispersibility of the colorant in the binder resin.

Mixing with a Henschel mixer is performed while adjusting the peripheral speed of stirring and the stirring time. The peripheral speed is preferably 10 m / sec or more and 30 m / sec or less from the viewpoint of improving the dispersibility of the colorant. The stirring time is preferably 1 minute or more and 10 minutes or less from the viewpoint of improving the dispersibility of the colorant.

Next, the melt kneading of the toner raw material can be performed using a known kneader such as a closed kneader, a uniaxial or biaxial kneader, or a continuous open roll kneader. In the production method of the present invention, an open roll type kneader is preferable from the viewpoint of improving the dispersibility of the colorant and improving the yield of toner particles after pulverization.

The open roll type kneader is one in which the melt-kneading portion is not sealed and is open, and the kneading heat generated during melt-kneading can be easily dissipated. The open roll type kneader used in the present invention is provided with a plurality of raw material supply ports and kneaded material discharge ports provided along the axial direction of the roll, and is a continuous open roll type kneader from the viewpoint of production efficiency. Is preferable.

The open roll type kneader preferably has at least two kneading rolls having different temperatures.

From the viewpoint of improving the mixing property of the toner raw material, the set temperature of the roll is preferably 10 ° C. or higher than the softening point of the resin.

Further, from the viewpoint of improving the adhesion of the kneaded material to the roll on the upstream side and strongly kneading the kneaded material on the downstream side, it is preferable that the set temperature of the roll on the upstream side is higher than that on the downstream side.

The rolls preferably have different peripheral velocities from each other. In the open roll type kneader equipped with the above two rolls, from the viewpoint of improving the fixability of the liquid developer, the heating roll having a high temperature is the high rotation side roll, and the cooling roll having a low temperature has a low rotation. It is preferably a side roll.

The peripheral speed of the high rotation side roll is preferably 2 m / min or more, more preferably 5 m / min or more, and preferably 100 m / min or less, more preferably 75 m / min or less. The peripheral speed of the low rotation side roll is preferably 2 m / min or more, more preferably 4 m / min or more, and preferably 100 m / min or less, more preferably 60 m / min or less, still more preferably 50 m / min or less. Is. Further, the ratio of the peripheral speeds of the two rolls (low rotation side roll / high rotation side roll) is preferably 1/10 or more, more preferably 3/10 or more, and preferably 9/10 or less. More preferably, it is 8/10 or less.

The structure, size, material, etc. of each roll are not particularly limited. The surface of the roll has a groove used for kneading, and the shape thereof includes a linear shape, a spiral shape, a corrugated shape, and an uneven shape.

Next, after cooling the melt-kneaded product to a extent that it can be pulverized, toner particles can be obtained through a pulverization step and, if necessary, a classification step and the like.

The crushing step may be divided into multiple steps. For example, the melt-kneaded product may be roughly pulverized to about 1 to 5 mm and then further pulverized. Further, in order to improve the productivity in the pulverization step, the melt-kneaded product may be mixed with inorganic fine particles such as hydrophobic silica and then pulverized.

Examples of the crusher preferably used for coarse crushing include an atomizer, a rotoplex and the like, but a hammer mill and the like may also be used. Further, examples of the pulverizer preferably used for fine pulverization include a fluidized bed type jet mill, an airflow type jet mill, and a mechanical type mill.

Examples of the classifier used in the classification process include an airflow type classifier, an inertial type classifier, and a sieve type classifier. If necessary, the crushing step and the classification step may be repeated.

The volume median particle diameter (D ₅₀ ) of the toner particles obtained in this step is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm from the viewpoint of improving the productivity of the wet pulverization step described later. Hereinafter, it is more preferably 12 μm or less. The volume median particle size (D ₅₀ ) means a particle size in which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. It is preferable that the toner particles are further refined by wet pulverization or the like after being mixed with the dispersant and the insulating liquid.

The content of the toner particles is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, still more preferably 30 parts by mass or more, with respect to 100 parts by mass of the insulating liquid from the viewpoint of high-speed printability. It is 40 parts by mass or more, more preferably 50 parts by mass or more, and from the viewpoint of improving dispersion stability, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 70 parts by mass or less, and further. It is preferably 60 parts by mass or less.

The dispersant in the present invention is one or more selected from polyalkyleneimines having a molecular weight of 250 or less, halogenated hydrocarbons having 16 or more carbon atoms, preferably 16 or more and 24 or less carbon atoms, and polyolefins having a reactive functional group. It contains a reactant X with a hydrocarbon group-containing compound having a number average molecular weight of 500 or more.

Examples of the polyalkyleneimine include polyethyleneimine such as tetraethylenepentamine and polypropyleneimine such as tetrapropylenepentamine, and among these, polyethyleneimine is preferable.

The average number of moles of ethylene added in polyethyleneimine is preferably 5 or less from the viewpoint of heat agglomeration of toner particles at high temperature, and from the viewpoint of improving the dispersion stability of toner particles to improve storage stability. Therefore, it is preferably 3 or more.

The polyalkyleneimine preferably has a linear structure from the viewpoint of heat cohesiveness of toner particles at high temperature.

The molecular weight of the polyalkyleneimine is 250 or less, preferably 230 or less, more preferably 200 or less, from the viewpoint of heat cohesiveness of the toner particles at high temperature, and the dispersion stability of the toner particles is improved. From the viewpoint of improving storage stability, it is preferably 150 or more, more preferably 170 or more. Here, the molecular weight of polyalkyleneimine may be a number average molecular weight.

The number average molecular weight of the hydrocarbon group-containing compound is preferably 500 or more, more preferably 800 or more, and the toner particles at a high temperature from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint of thermal cohesiveness, it is preferably 8,500 or less, more preferably 3,000 or less.

Examples of the reactive functional group include a carboxy group, an epoxy group, a formyl group, an isocyanate group and the like, and among these, a carboxy group or an epoxy group is preferable from the viewpoint of safety and reactivity. Therefore, the polyolefin having a reactive functional group is preferably a carboxylic acid compound. Carboxylic acid compounds include fumaric acid, maleic acid, ethane acid, propanoic acid, butanoic acid, succinic acid, oxalic acid, malonic acid, tartaric acid, their anhydrides, and alkyl groups having 1 or more and 3 or less carbon atoms. Esters and the like can be mentioned. Specific examples of the hydrocarbon group-containing compound include halogenated alkanes such as chlorooctadecane, polyolefin succinic anhydride, and chlorinated polyolefins.

From the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, the hydrocarbon group-containing compound preferably has a polyolefin skeleton, more preferably has a polyisobutene skeleton and / or a polypropylene skeleton, and is wet-ground. From the viewpoint of improving the properties, it is more preferable to have a polyisobutene skeleton.

The carbon number of the polyolefin skeleton is preferably 35 or more, more preferably 50 or more, and the heat cohesiveness of the toner particles at a high temperature from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint of the above, it is preferably 700 or less, more preferably 600 or less, and further preferably 500 or less. The carbon number of the polyolefin skeleton can be calculated from the number average molecular weight of the hydrocarbon group-containing compound.

Therefore, among the hydrocarbon group-containing compounds, polyolefin having a reactive functional group is preferable, and polyisobutene having a reactive functional group is more preferable. The content of the polyolefin having a reactive functional group in the hydrocarbon group-containing compound is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 100% by mass. ..

In the reaction between the polyalkyleneimine and the hydrocarbon group-containing compound, for example, the hydrocarbon group-containing compound is added dropwise to the polyalkyleneimine dissolved in the organic solvent, and the reaction is carried out at 150 to 160 ° C., and then the organic solvent is depressurized. Examples include a method of distilling off. The end point of the reaction can be confirmed, for example, by the disappearance of the peak derived from the acid anhydride by IR analysis.

The content of the reactant X in the dispersant is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 100% by mass.

Examples of the dispersant other than the reaction product X include a copolymer of alkyl methacrylate / amino group-containing methacrylate, a copolymer of α-olefin / vinylpyrrolidone, and the like.

The content of the dispersant is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and further preferably 0.5 part by mass or more with respect to 100 parts by mass of the toner particles from the viewpoint of dispersion stability of the toner particles. From the viewpoint of chargeability and fixability of the toner, the amount is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 3.5 parts by mass or less.

The insulating liquid in the present invention means a liquid through which electricity does not easily flow, but in the present invention, the conductivity of the insulating liquid is preferably 1.0 × 10 ^-11 S / m or less, more preferably 5.0. It is × 10 ^-12 S / m or less, and preferably 1.0 × 10 ^-13 S / m or more.

Examples of the insulating liquid include hydrocarbon-based insulating liquids such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes, and vegetable oils. In the present invention, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability, the insulating liquid preferably contains a hydrocarbon-based insulating liquid, and contains an aliphatic hydrocarbon-based solvent. It is more preferable, and it is further preferable to contain polyisobutene from the viewpoint of dispersion stability and chargeability.

In the present invention, polyisobutene is obtained by polymerizing isobutene by a known method, for example, a cationic polymerization method using a catalyst, and then hydrogenating the double bond at the terminal.

Examples of the catalyst used in the cationic polymerization method include aluminum chloride, acidic ion exchange resin, sulfuric acid, boron fluoride and a complex thereof. Further, the polymerization reaction can be controlled by adding a base to the catalyst.

The degree of polymerization of polyisobutene is preferably 8 or less, more preferably 6 or less, still more preferably 5 or less, still more preferably 4 or less, from the viewpoint of improving the low temperature fixability of the toner. Further, from the viewpoint of suppressing charger contamination, it is preferably 2 or more, and more preferably 3 or more.

It is preferable that the unreacted component of isobutylene and the high boiling point component having a high degree of polymerization generated during the polymerization reaction are removed by distillation. Examples of the distillation method include a simple distillation method, a continuous distillation method, a steam distillation method and the like, and these methods can be used alone or in combination. The apparatus used for distillation is not particularly limited in material, shape, model and the like, and examples thereof include a distillation column filled with a filler such as Raschig ring and a shelf-stage distillation column having a dish-shaped shelf. The number of theoretical plates indicating the separation ability of the distillation column is preferably 10 or more. In addition, conditions such as the amount of feed to the distillation column, the reflux ratio, and the amount of withdrawal can be appropriately selected by the distillation apparatus.

Since the product obtained by the polymerization reaction has a double bond at the polymerization terminal, a hydrogenated product is obtained by the hydrogenation reaction. The hydrogenation reaction can be carried out, for example, by using nickel, palladium or the like as a hydrogenation catalyst at a temperature of 180 to 230 ° C., and bringing hydrogen into contact at a pressure of 2 to 10 MPa.

Examples of commercially available insulating liquids containing polyisobutene include "NAS-3", "NAS-4", and "NAS-5H" (all of which are manufactured by NOF CORPORATION). One or more of these can be combined.

The boiling point of the hydrocarbon-based insulating liquid is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, still more preferably 160 ° C. or higher, from the viewpoint of further improving the dispersion stability of the toner particles and improving the storage stability. It is more preferably 180 ° C. or higher, further preferably 200 ° C. or higher, still more preferably 220 ° C. or higher, and from the viewpoint of further improving the low-temperature fixability of the toner, the pulverizability of the toner is further improved during wet grinding and the particle size is small. From the viewpoint of obtaining the liquid developer of the above, the temperature is preferably 300 ° C. or lower, more preferably 280 ° C. or lower, and further preferably 260 ° C. or lower.

The content of the hydrocarbon-based insulating liquid is preferably 5% by mass or more, more preferably 20% by mass or more, still more preferably 40% by mass or more, still more preferably 60% by mass or more, still more preferably 60% by mass or more in the insulating liquid. It is 80% by mass or more, more preferably 90% by mass or more.

The boiling point of the insulating liquid is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, still more preferably 160 ° C. or higher, still more preferably 160 ° C. or higher, from the viewpoint of further improving the dispersion stability of the toner particles and improving the storage stability. It is 180 ° C. or higher, more preferably 200 ° C. or higher, further preferably 220 ° C. or higher, and from the viewpoint of further improving the low-temperature fixability of the toner, the pulverizability of the toner is further improved during wet grinding to obtain a toner having a small particle size. From the viewpoint of obtaining particles, the temperature is preferably 300 ° C. or lower, more preferably 280 ° C. or lower, and further preferably 260 ° C. or lower. When two or more kinds of insulating liquids are combined, it is preferable that the boiling point of the combined insulating liquid mixture is within the above range.

The viscosity of the insulating liquid at 25 ° C. is preferably 1 mPa · s or more, more preferably 1.5 mPa · s, from the viewpoint of improving the developability and the storage stability of the toner particles in the liquid developer. The above, and preferably 100 mPa · s or less, more preferably 50 mPa · s or less, further preferably 20 mPa · s or less, still more preferably 10 mPa · s or less, still more preferably 5 mPa · s or less.

In addition to binder resins, colorants, dispersants, and insulating liquids, liquid developers include mold release agents, charge control agents, charge control resins, magnetic powders, fluidity improvers, conductivity modifiers, and fibrous forms. Additives such as a reinforcing filler such as a substance, an antioxidant, and a cleaning property improving agent may be appropriately contained.

The liquid developer is obtained by dispersing the toner particles in an insulating liquid in the presence of a dispersant. From the viewpoint of reducing the particle size of the toner particles and reducing the viscosity of the liquid developer, it is preferable to disperse the toner particles in an insulating liquid and then wet-pulverize the toner particles to obtain a liquid developer.

As a method of mixing the toner particles, the dispersant, and the insulating liquid, a method of stirring with a stirring / mixing device or the like is preferable.

The stirring / mixing device is not particularly limited, but a high-speed stirring / mixing device is preferable from the viewpoint of improving the productivity and storage stability of the toner particle dispersion, and specifically, Despa (manufactured by Asada Iron Works Co., Ltd.). TK Homo Mixer, TK Homo Disperser, TK Robomix (all manufactured by Primex Co., Ltd.), Claire Mix (manufactured by M Technique Co., Ltd.), Kady Mill (manufactured by Kady International Co., Ltd.) ) Etc. are preferable.

By mixing with the high-speed stirring and mixing device, the toner particles are pre-dispersed, the toner particle dispersion liquid can be obtained, and the productivity of the liquid developer by the next wet pulverization is improved.

From the viewpoint of improving the image density, the solid content concentration of the toner particle dispersion is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 33% by mass or more, and the toner particles are stably dispersed. From the viewpoint of improving the properties and the storage stability, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

Wet pulverization is a method of mechanically pulverizing toner particles dispersed in an insulating liquid in a state of being dispersed in the insulating liquid.

As the device to be used, for example, a commonly used stirring / mixing device such as an anchor blade can be used. Among the stirring and mixing devices, high-speed stirring and mixing devices such as Despa (manufactured by Asada Iron Works Co., Ltd.) and TK Homomixer (manufactured by Primix Corporation), crushers or kneaders such as roll mills, bead mills, kneaders, and extruders. And so on. A plurality of these devices can be combined.

Among these, the use of a bead mill is used from the viewpoint of reducing the particle size of the toner particles, improving the dispersion stability of the toner particles to improve the storage stability, and reducing the viscosity of the dispersion liquid. preferable.

In the bead mill, toner particles having a desired particle size and particle size distribution can be obtained by controlling the particle size and filling rate of the media used, the peripheral speed of the rotor, the residence time, and the like.

As described above, the liquid developer of the present invention is
Step 1: A step of melt-kneading a binder resin containing a polyester resin and a colorant and pulverizing them to obtain toner particles.
Step 2: A step of mixing the toner particles obtained in Step 1 and a dispersant and dispersing them in an insulating liquid to obtain a toner particle dispersion liquid, and a step 3: Wetting the toner particle dispersion liquid obtained in Step 2. It is preferably produced by a method including a step of pulverizing and obtaining a liquid developer.

From the viewpoint of improving the image density, the solid content concentration of the liquid developer is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and the dispersion stability of the toner particles. From the viewpoint of improving storage stability, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

The volume median particle diameter (D ₅₀ ) of the toner particles in the liquid developer is preferably 0.5 μm or more, more preferably 1.0 μm or more, still more preferably 1.5 μm or more, from the viewpoint of reducing the viscosity of the liquid developer. Yes, and from the viewpoint of improving the image quality of the liquid developer, it is preferably 5 μm or less, more preferably 3 μm or less, and further preferably 2.5 μm or less.

The viscosity of the liquid developer having a solid content concentration of 25% by mass at 25 ° C. is preferably 3 mPa · s or more, more preferably 5 mPa · s, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. Above, more preferably 6 mPa · s or more, further preferably 7 mPa · s or more, and from the viewpoint of improving the fixability of the liquid developer, preferably 50 mPa · s or less, more preferably 40 mPa · s or less, and further. It is preferably 37 mPa · s or less, more preferably 35 mPa · s or less, still more preferably 32 mPa · s or less, still more preferably 28 mPa · s or less, still more preferably 24 mPa · s or less, still more preferably 20 mPa · s or less, still more preferably. It is 16 mPa · s or less.

Regarding the above-described embodiment, the present invention further discloses the following liquid developer.

<1> A liquid developer containing a binder resin containing a polyester resin, toner particles containing a colorant, a dispersant, and an insulating liquid, wherein the polyester resin contains an alcohol component and 100 mol of the alcohol component. It is a polycondensate with a carboxylic acid component containing 40 mol or more of a trivalent or more carboxylic acid compound, and the dispersant is a hydrocarbon having a molecular weight of 250 or less and a hydrocarbon having 16 or more carbon atoms. A liquid developer containing a reaction product with a hydrocarbon group-containing compound having a number average molecular weight of 500 or more, which is one or more selected from hydrogen and a polyester having a reactive functional group.

<2> The liquid developer according to <1>, wherein the polyalkyleneimine has a molecular weight of 150 or more, preferably 170 or more, and 250 or less, preferably 230 or less, more preferably 200 or less.
<3> The liquid developer according to <1> or <2> above, wherein the polyalkyleneimine is one or more selected from polyethyleneimine and polypropyleneimine, preferably polyethyleneimine.
<4> The liquid developer according to <1> or <2> above, wherein the polyalkyleneimine is polyethyleneimine having an average number of moles of ethylene added of 3 or more and 5 or less.
<5> The liquid development according to any one of <1> to <4> above, wherein the number average molecular weight of the hydrocarbon group-containing compound is 500 or more, preferably 800 or more, and 8,500 or less, preferably 3,000 or less. Agent.
<6> The liquid developer according to any one of <1> to <5> above, wherein the halogenated hydrocarbon has 16 or more and 24 or less carbon atoms.
<7> The polyolefin having a reactive functional group is a carboxylic acid compound, preferably fumaric acid, maleic acid, ethane acid, propanoic acid, butanoic acid, succinic acid, oxalic acid, malonic acid, tartaric acid, and anhydrides thereof. Alternatively, the liquid developer according to <6> above, which is an alkyl ester having an alkyl group having 1 or more and 3 or less carbon atoms.
<8> The above-mentioned <1> to <, wherein the hydrocarbon group-containing compound has a polyolefin skeleton having 35 or more carbon atoms, preferably 50 or more carbon atoms, 700 or less, preferably 600 or less, and more preferably 500 or less. 7> The liquid developer according to any one.
<9> The liquid developer according to <8> above, wherein the polyolefin skeleton is a polyisobutene skeleton and / or a polypropylene skeleton, preferably a polyisobutene skeleton.
<10> The liquid according to any one of <1> to <9>, wherein the softening point of the polyester resin is 90 ° C. or higher, preferably 100 ° C. or higher, and 130 ° C. or lower, preferably 120 ° C. or lower. Developer.
<11> The above-mentioned <1> to <10>, wherein the glass transition temperature of the polyester resin is 50 ° C. or higher, preferably 55 ° C. or higher, and 80 ° C. or lower, more preferably 75 ° C. or lower. Liquid developer.
<12> The acid value of the polyester resin is 40 mgKOH / g or more, preferably 50 mgKOH / g or more, and 100 mgKOH / g or less, preferably 80 mgKOH / g or less, any of the above <1> to <11>. The liquid developer described.
<13> The liquid development according to any one of <1> to <12> above, wherein the polyester resin is one or more selected from a polyester resin and a composite resin containing a polyester resin and a styrene resin. Agent.
<14> The liquid developer according to <13>, wherein the polyester resin is a polycondensate of an alcohol component containing a divalent or higher alcohol and a carboxylic acid component containing a divalent or higher carboxylic acid compound.
<15> The insulating liquid is at least one selected from the group consisting of hydrocarbon-based insulating liquids, halogenated hydrocarbons, polysiloxanes, and vegetable oils, preferably hydrocarbon-based insulating liquids, more preferably aliphatic. The liquid developer according to any one of <1> to <14> above, which contains a hydrocarbon-based solvent, more preferably polyisobutene.
<16> The solid content concentration is 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, and 50% by mass or less, preferably 45% by mass or less, more preferably 40% by mass. The liquid developer according to any one of <1> to <15> described below.
<17> The solid content concentration is 25% by mass, and the viscosity at 25 ° C. is 3 mPa · s or more, preferably 5 mPa · s or more, more preferably 6 mPa · s or more, still more preferably 7 mPa · s or more, and , 50 mPa · s or less, preferably 40 mPa · s or less, more preferably 37 mPa · s or less, further preferably 35 mPa · s or less, still more preferably 32 mPa · s or less, still more preferably 28 mPa · s or less, still more preferably 24 mPa · s. The liquid developer according to any one of <1> to <16> above, which is s or less, more preferably 20 mPa · s or less, still more preferably 16 mPa · s or less.
<18> The method for producing a liquid developer according to any one of <1> to <17>.
Step 1: A step of melt-kneading a binder resin containing a polyester resin and a colorant and pulverizing them to obtain toner particles.
Step 2: A step of mixing the toner particles obtained in Step 1 and a dispersant and dispersing them in an insulating liquid to obtain a toner particle dispersion liquid, and a step 3: Wetting the toner particle dispersion liquid obtained in Step 2. A method for producing a liquid developer, which comprises a step of pulverizing to obtain a liquid developer.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The physical properties of the resin and the like were measured by the following methods.

[Resin softening point]
Using the flow tester "CFT-500D" (manufactured by Shimadzu Corporation), while heating a 1 g sample at a heating rate of 6 ° C / min, a load of 1.96 MPa was applied by a plunger, and the diameter was 1 mm and the length was 1 mm. Push out from the nozzle. The amount of plunger drop of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is used as the softening point.

[Resin glass transition temperature]
Using the differential scanning calorimeter "DSC210" (manufactured by Seiko Electronics Co., Ltd.), weigh 0.01 to 0.02 g of the sample in an aluminum pan, raise the temperature to 200 ° C, and then lower the temperature from that temperature to 0 at a temperature reduction rate of 10 ° C / min. Cool to ° C. Next, the sample is heated at a heating rate of 10 ° C./min, and the endothermic peak is measured. The temperature at the intersection of the extension of the baseline below the maximum peak temperature of heat absorption and the tangent line indicating the maximum slope from the rising portion of the peak to the peak of the peak is defined as the glass transition temperature.

[Acid value of resin]
Measure by the method of JIS K0070. However, only the measurement solvent is changed from the mixed solvent of ethanol and ether specified in JIS K0070 to the mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Volume medium particle size of toner particles before mixing with insulating liquid]
Measuring machine: Coulter Multisizer II (manufactured by Beckman Coulter Co., Ltd.)
Aperture diameter: 100 μm
Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter Co., Ltd.)
Electrolyte: Isoton II (manufactured by Beckman Coulter Co., Ltd.)
Dispersion solution: Emalgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB (griffin): 13.6) was dissolved in an electrolytic solution to adjust to 5% by mass. Dispersion condition: 10 mg of measurement sample in 5 mL of the dispersion solution Is added and dispersed for 1 minute with an ultrasonic disperser (machine name: US-1, manufactured by SND Co., Ltd., output: 80 W). Then, 25 mL of the electrolytic solution is added and further dispersed with an ultrasonic disperser for 1 minute to prepare a sample dispersion.
Measurement conditions: Add the sample dispersion to 100 mL of the electrolytic solution so that the particle size of 30,000 particles can be measured in 20 seconds, measure 30,000 particles, and measure the volume from the particle size distribution. Determine the medium particle size (D ₅₀ ).

[Number average molecular weight of polyalkyleneimine (Mn)]
The molecular weight distribution is measured by the gel permeation chromatography (GPC) method shown below, and the number average molecular weight is determined.
(1) Preparation of sample solution Dissolve polyalkyleneimine at 0.15 mol / L in a solution of Na ₂ SO ₄ in a 1% acetic acid aqueous solution so that the concentration becomes 0.2 g / 100 mL. Next, this solution is filtered using a fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 0.2 μm to remove insoluble components, and used as a sample solution.
(2) Molecular weight measurement Using the following measuring device and analysis column, a solution of Na ₂ SO ₄ dissolved in a 1% acetic acid aqueous solution at 0.15 mol / L as an eluent was flowed at a flow rate of 1 mL per minute at 40 ° C. Stabilize the column in a constant temperature bath. Inject 100 μL of the sample solution into it and measure. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve at this time includes several types of standard pullulan (P-5 (5.9 x 10 ³ ), P-50 (4.73 x 10 ⁴ ), P-200 (2.12 x 10 ⁵ ) manufactured by Showa Denko KK). Use a sample prepared using P-800 (7.08 x 10 ⁵ )) as a standard sample. The molecular weight is shown in parentheses.
Measuring device: HLC-8320GPC (manufactured by Tosoh Corporation)
Analytical column: α + α-M + α-M (manufactured by Tosoh Corporation)

[Number average molecular weight (Mn) of hydrocarbon group-containing compounds]
(1) Preparation of sample solution The sample was dissolved in tetrahydrofuran so that the concentration was 0.5 g / 100 mL. Next, this solution was filtered using a fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) having a pore size of 2 μm to remove insoluble components, and used as a sample solution.
(2) Molecular weight distribution measurement Using the following measuring device and analytical column, tetrahydrofuran is flowed as an eluent at a flow rate of 1 mL per minute, and the column is stabilized in a constant temperature bath at 40 ° C. Inject 100 μL of the sample solution into it and measure. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. At this time, the calibration curve includes several types of monodisperse polystyrene (A-500 (Mw 5.0 × 10 ² ), A-1000 (Mw 1.01 × 10 ³ ), A-2500 (Mw 2.63 × 10) manufactured by Toso Co., Ltd.). ³ ), A-5000 (Mw 5.97 × 10 ³ ), F-1 (Mw 1.02 × 10 ⁴ ), F-2 (Mw 1.81 × 10 ⁴ ), F-4 (Mw 3.97 × 10 ⁴ ), F-10 (Mw 9.64 × 10 ⁴ ), F-20 (Mw 1.90 × 10 ⁵ ), F-40 (Mw 4.27 × 10 ⁵ ), F-80 (Mw 7.06 × 10 ⁵ ), F-128 (Mw 1.09 × 10 ⁶⁾ )) Is used as a standard sample. The molecular weight is shown in parentheses.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: GMHXL + G3000HXL (manufactured by Tosoh Corporation)

[Conductivity of insulating liquid]
Put 25 g of insulating liquid into a 40 mL glass sample tube "Screw No. 7" (manufactured by Maruemu Co., Ltd.), and use a non-aqueous conductivity meter "DT-700" (manufactured by Dispersion Technology) to attach the electrodes. Immerse in an insulating liquid and measure 20 times at 25 ° C to calculate the average value and measure the conductivity. The smaller the value, the higher the resistance.

[Boiling point of insulating liquid]
Using the differential scanning calorimeter "DSC210" (manufactured by Seiko Electronics Co., Ltd.), weigh 6.0 to 8.0 mg of the sample into an aluminum pan, raise the temperature to 350 ° C at a heating rate of 10 ° C / min, and set the endothermic peak. Measure. The endothermic peak on the highest temperature side is the boiling point.

[Viscosity of insulating liquid and liquid developer with a solid content concentration of 25% by mass at 25 ° C]
Put 6 to 7 mL of the measuring solution in a 10 mL screw tube, and use the rotary vibration viscometer "Viscomate VM-10A-L" (manufactured by SEKONIC Corporation, detection terminal: titanium, φ8 mm) at the tip of the detection terminal. Fix the screw tube at the position where the liquid level comes 15 mm above the part, and measure the viscosity at 25 ° C.

[Solid concentration of toner particle dispersion and liquid developer]
10 parts by mass of the sample is diluted with 90 parts by mass of hexane and rotated for 20 minutes at a rotation speed of 25,000 r / min using a centrifuge "H-201F" (manufactured by Kokusan Co., Ltd.). After standing, the supernatant is removed by decantation, diluted with 90 parts by mass of hexane, and centrifuged again under the same conditions. After removing the supernatant by decantation, the lower layer is dried in a vacuum dryer at 0.5 kPa at 40 ° C. for 8 hours, and the solid content concentration is calculated from the following formula.

[Volume medium particle size of toner particles in liquid developer (D ₅₀ )]
Using the laser diffraction / scattering particle size measuring device "Mastersizer 2000" (manufactured by Malvern), Isopar L (manufactured by Exxon Mobile, isoparaffin, viscosity at 25 ° C, viscosity 1 mPa · s) is added to the measuring cell, and the scattering intensity is increased. The volume median particle diameter (D ₅₀ ) is measured under the conditions of a particle refractive index of 1.58 (imaginary part 0.1) and a dispersion medium refractive index of 1.42 at a concentration of 5 to 15%.

Resin Production Example 1 [Resin A to C]
Put the raw material monomers other than trimellitic anhydride shown in Table 1, the esterification catalyst and the polymerization inhibitor into a 10 L four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and use a mantle heater. Then, the temperature was raised from 180 ° C. to 200 ° C. over 1 hour, reacted at 200 ° C., trimellitic anhydride was added, and the reaction was carried out at 200 ° C. until the softening point shown in Table 1 was reached. , Polyester resins (resins A to C) having the physical properties shown in Table 1 were obtained.

Resin Production Example 2 [Resin D]
Place the raw material monomers and esterification catalysts shown in Table 1 in a 10 L four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer and thermocouple, and use a mantle heater to heat from 180 ° C to 210 ° C for 4 hours. After the temperature was raised over and reacted at 210 ° C. for 4 hours, the reaction was further carried out at 8.3 kPa until the softening point shown in Table 1 was reached to obtain a polyester resin (resin D) having the physical properties shown in Table 1. Obtained.

Dispersant Production Example 1 [Dispersants A, F, G]
The polyalkyleneimine shown in Table 2 was placed in a 2 L four-necked flask equipped with a cooling tube, a nitrogen introduction tube, a stirrer, a dehydration tube and a thermocouple, and the inside of the reaction vessel was replaced with nitrogen gas. With stirring, a solution dissolved in polyisobutene succinic anhydride (PIBSA) shown in Table 2 was added dropwise at room temperature over 1 hour. After completion of the dropping, the mixture was kept at room temperature for 30 minutes. Then, the inside of the reaction vessel was heated to 150 ° C. and held for 1 hour, then heated to 160 ° C. and held for 1 hour. The solvent was distilled off by reducing the pressure to 8.3 kPa at 160 ° C., and the time when the peak (1780 cm ^-1 ) of the acid anhydride derived from PIBSA disappeared from the IR analysis and the peak (1700 cm ^-1 ) derived from the imide bond was generated. Dispersants A, F, and G having the physical properties shown in Table 2 were obtained as reaction end points.

Dispersant Production Example 2 [Dispersants B to E]
2L of polyalkyleneimine, maleic anhydride-modified polypropylene (PPSA), and xylene (manufactured by Wako Pure Chemical Industries, Ltd.) shown in Table 2 equipped with a cooling tube, nitrogen introduction tube, stirrer, dehydration tube, and thermocouple. It was placed in a four-necked flask and the inside of the reaction vessel was replaced with nitrogen gas. Then, the inside of the reaction vessel was heated to 150 ° C. and held for 1 hour, then heated to 160 ° C. and held for 1 hour. The solvent was distilled off by reducing the pressure to 8.3 kPa at 160 ° C., and the time when the PPSA-derived acid anhydride peak (1780 cm ^-1 ) disappeared from the IR analysis and the imide bond-derived peak (1700 cm ^-1 ) occurred. Dispersants B to E having the physical properties shown in Table 2 were obtained as reaction end points.

Dispersant Production Example 3 [Dispersant H]
250 g of 12-hydroxystearic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 55 g of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction solvent, 2.5 g of dibutyltin oxide as an esterification catalyst, nitrogen introduction tube, dehydration tube The mixture was placed in a 500 mL four-necked flask equipped with a stirrer and a thermocouple, heated to 190 ° C. and reacted for 5 hours to obtain a condensate (p-12-HSA) having a number average molecular weight of 1400.
300 g of the obtained condensate, 20 g of tetraethylenepentamine (manufactured by Kanto Kagaku Co., Ltd.), and 320 g of xylene (manufactured by Wako Pure Chemical Industries, Ltd.) were added to a cooling tube, nitrogen introduction tube, stirrer, dehydration tube and thermocouple. It was placed in a 2 L four-necked flask equipped with a pair, and the inside of the reaction vessel was replaced with nitrogen gas. Then, the inside of the reaction vessel was heated to 150 ° C. and held for 1 hour, then heated to 160 ° C. and held for 1 hour. Under reduced pressure to 8.3kPa at 160 ° C. The solvent was evaporated and to the peak of a carboxylic acid derived from condensation of 12-hydroxystearic acid from IR analysis (1780 cm ^-1) disappeared, a peak derived from an amide bond (1700 cm ^-1 ) Was generated as the reaction end point, and a dispersant H having the physical properties shown in Table 2 was obtained.

Examples 1-6 and Comparative Examples 1-5
Rotate 80 parts by mass of the binder resin and 20 parts by mass of the colorant "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue 15: 3) shown in Table 3 in advance using a 20 L Henschel mixer. After stirring and mixing for 3 minutes at a frequency of 1500 r / min (peripheral speed 21.6 m / sec), melt-kneading was performed under the conditions shown below.

[Melting and kneading conditions]
A continuous double open roll type kneader "Kneedex" (manufactured by Nippon Coke Industries Co., Ltd., roll outer diameter: 14 cm, effective roll length: 55 cm) was used. The operating conditions of the continuous double open roll type kneader are high rotation side roll (front roll) rotation speed 75r / min (peripheral speed 32.4m / min), low rotation side roll (back roll) rotation speed 35r / min ( The peripheral speed was 15.0 m / min), and the roll gap at the end on the side of the kneaded material supply port was 0.1 mm. The heating medium temperature and cooling medium temperature in the roll are 90 ° C on the raw material input side of the high rotation side roll and 85 ° C on the kneaded material discharge side, 35 ° C on the raw material input side of the low rotation side roll and 35 ° C on the kneaded material discharge side. there were. The supply speed of the raw material mixture to the kneader was 10 kg / h, and the average residence time in the kneader was about 3 minutes.

The kneaded product obtained above was rolled and cooled with a cooling roll, and then roughly pulverized to about 1 mm using a hammer mill. The obtained coarsely pulverized product was finely pulverized and classified by an air flow jet mill "IDS" (manufactured by Nippon Pneumatic Co., Ltd.) to obtain toner particles having a volume median particle diameter (D ₅₀ ) of 10 μm.

35 parts by mass of the obtained toner particles and insulating liquid "NAS-4" (manufactured by Nichiyu Co., Ltd., polyisobutene (degree of polymerization 4), conductivity: 1.52 x 10 ^-12 S / m, boiling point: 247 ° C, 25 Viscosity at ° C: 2 mPa · s) 63.95 parts by mass and 1.05 parts by mass of the dispersant shown in Table 3 (3 parts by mass with respect to 100 parts by mass of toner particles) are placed in a 1 L volume polyethylene container, and "TK Robomix" Using (manufactured by Primix Co., Ltd.), the mixture was stirred for 30 minutes at a rotation speed of 7,000 r / min under ice-cooling to obtain a toner particle dispersion having a solid content concentration of 36% by mass.

Next, the obtained toner particle dispersion was rotated by a 6-cylinder sand mill "TSG-6" (manufactured by Imex Co., Ltd.) at a volume filling rate of 60% by volume using zirconia beads having a diameter of 0.8 mm. Wet pulverization was performed at 1300 r / min (peripheral speed 4.8 m / sec) until the volume medium particle size (D ₅₀ ) shown in Table 3 was reached. After removing the beads by filtration, the insulating liquid "NAS-4" (manufactured by Nichiyu Co., Ltd., polyisobutene, conductivity: 1.52 x 10 ^-12 S / m, boiling point: 247 ° C, for 100 parts by mass of the filtrate, Viscosity at 25 ° C.: 2 mPa · s) 44 parts by mass was added and diluted to obtain a liquid developer having the physical characteristics shown in Table 3 in which the solid content concentration was adjusted to 25% by mass.

Test Example 1 [Storage stability]
5 g of the liquid developer was placed in a 10 mL screw tube and stored in a constant temperature bath at 50 ° C. for 15 hours. The volume median particle diameter (D ₅₀ ) of the toner particles before and after storage was measured, and the storage stability was evaluated from the value (%) of D ₅₀ after storage / D ₅₀ × 100 before storage. The results are shown in Table 3. The closer the value is to 100%, the better the storage stability. The results are shown in Table 3.

Test Example 2 [Aggregation start temperature]
5 g of the liquid developer was placed in a 10 mL screw tube and stored in a constant temperature bath at 60 ° C. for 3 minutes, and the volume median particle diameter (D ₅₀ ) of the toner particles after storage was measured. Further, the temperature of the constant temperature bath was raised by 5 ° C., and the D ₅₀ of the toner particles after storage was measured in the same manner. The temperature at the time when D ₅₀ exceeded 10 μm was defined as the aggregation start temperature. It is shown that the lower the aggregation start temperature, the better the heat cohesiveness. The results are shown in Table 3.

From the above results, it can be seen that the liquid developing agents of Examples 1 to 6 have low viscosity, good storage stability and good toner cohesiveness when heated at high temperature, and the toner particles have a small particle size.
On the other hand, Comparative Examples 1 and 2 in which the polyester resin does not use a carboxylic acid compound having a trivalent or higher valence or is in a small amount lack storage stability. Further, Comparative Examples 3 and 4 in which the molecular weight of the polyalkyleneimine used as the dispersant was too large lacked toner cohesiveness, and Comparative Example 5 in which the dispersant in which the hydrocarbon group was substituted with a hydroxyl group had a viscosity. Is high, and both storage stability and toner cohesiveness are insufficient.

The liquid developer of the present invention is suitably used for developing a latent image formed in, for example, an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

Claims (9)

A liquid developer containing a binder resin containing a polyester resin, toner particles containing a colorant, a dispersant, and an insulating liquid, wherein the polyester resin is based on an alcohol component and 100 mol of the alcohol component. 40 is a polycondensate of mol of trivalent or higher carboxylic acid component containing a carboxylic acid compound, wherein the dispersing agent is substantially hydrocarbon radical containing the following molecular weight 250 polyalkyleneimine the number or average molecular weight 500 containing reactant comprising a compound, Ru der least one hydrocarbon group-containing compound is selected from the group consisting of polyolefins having halogenated carbon number 16 or more hydrocarbons, and a reactive functional group, Liquid developer. The liquid developer according to claim 1, wherein the polyalkyleneimine has a molecular weight of 150 or more and 250 or less. The liquid developer according to claim 1 or 2, wherein the polyalkyleneimine is polyethyleneimine having an average number of moles of ethylene added of 3 or more and 5 or less. The liquid developer according to any one of claims 1 to 3, wherein the hydrocarbon group-containing compound has a polyolefin skeleton having 35 or more carbon atoms and 700 or less carbon atoms. Polyolefin skeleton, a polyisobutene backbone and / or polypropylene backbone, a liquid developer according to claim 4 Symbol mounting. The liquid developer according to any one of claims 1 to 5, wherein the polyester resin has an acid value of 40 mgKOH / g or more and 100 mgKOH / g or less. The liquid developer according to any one of claims 1 to 6, wherein the insulating liquid contains a hydrocarbon-based insulating liquid. The liquid developer according to any one of claims 1 to 7, wherein the solid content concentration is 10% by mass or more and 50% by mass or less. The method for producing a liquid developer according to any one of claims 1 to 8.
Step 1: A step of melt-kneading a binder resin containing a polyester resin and a colorant and pulverizing them to obtain toner particles.
Step 2: A step of mixing the toner particles obtained in Step 1 and a dispersant and dispersing them in an insulating liquid to obtain a toner particle dispersion liquid, and a step 3: Wetting the toner particle dispersion liquid obtained in Step 2. A method for producing a liquid developer, which comprises a step of pulverizing to obtain a liquid developer.