JP6838827B2 - 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.

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 comprises a group consisting of _{C 10} , C ₁₁ and C ₁₂ hydrocarbons having a Cowley butanol number less than 30 for the purpose of providing a wet ink or toner for electrophotographic with reduced odor. Includes a liquid carrier containing at least one selected hydrocarbon, a polymer binder, and a fluid material having an opposing odor vector for _{C 10} , C ₁₁ and C _{12 hydrocarbons such as terpenes, in addition to colorants.} Inventions relating to wet inks for electrophotographics are disclosed.

Japanese Unexamined Patent Publication No. 2004-151735

From the viewpoint of energy efficiency, it is desired to fix the toner at a low temperature. In order to lower the fixing temperature, it is sufficient to add a plasticizer or the like to the toner to make it easier to melt the toner. However, when the toner is easily melted by the plasticizer, the image surface and the image surface are overlapped in close contact with each other. When the printed matter is stored, there arises a problem that the image surfaces adhere to each other, that is, so-called document offset is likely to occur.

The present invention relates to a liquid developer having excellent low temperature fixability and document offset resistance.

The present invention is a liquid developer containing toner particles containing a binder resin and a colorant, a terpene compound, a dispersant, and an insulating liquid, wherein the binder resin contains a polyester resin and the terpene is used. The present invention relates to a liquid developer having a molecular weight of a system compound of 100 or more and 210 or less.

The liquid developer of the present invention has the effects of being excellent in low-temperature fixability and document offset resistance.

The present invention is a liquid developer containing toner particles, a dispersant and an insulating liquid, and in addition to these, contains a terpene compound having a predetermined molecular weight, and is excellent in low temperature fixability and document offset resistance. It is a thing.

The reason for this effect is not clear, but the terpene compound dissolves in the insulating liquid and permeates into the toner particles, acting as a plasticizer to improve low-temperature fixability and volatilize during fixing. It is presumed that the volatilization of the terpene compound restores the glass transition temperature of the binder resin, which was once lowered in the process of manufacturing the liquid developer, and suppresses the occurrence of document offset.

In the liquid developer of the present invention, the toner particles contain a binder resin and a colorant, and the binder resin contains a polyester resin.

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, preferably an aliphatic diol having 2 or more and 20 or less carbon atoms, and more preferably 2 or more and 15 or less carbon atoms, or 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, bisphenol A, hydrogenated bisphenol A and the like. Specific examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. An aliphatic diol having a hydroxyl group bonded to a secondary carbon atom having 2 or more and 4 or less carbon atoms is preferable.

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, an aliphatic diol or an alkylene oxide adduct of bisphenol A represented by the formula (I) is preferable, and from the viewpoint of separability between the insulating liquid and the binder resin, the aliphatic diol is more preferable and has 2 carbon atoms. An aliphatic diol having a hydroxyl group bonded to a secondary carbon atom of 4 or more is more preferable, and 1,2-propanediol is further preferable. Further, from the viewpoint of low temperature fixability, the alkylene oxide adduct of bisphenol A represented by the formula (I) is more preferable. The content of the aliphatic diol or the alkylene oxide adduct of bisphenol A represented by the formula (I) is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more in the alcohol component. , More preferably 95 mol% or more, still more preferably 100 mol%. When an aliphatic diol 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 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. Specific examples of the dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and alkyl having 1 to 20 carbon atoms. Examples thereof include aliphatic dicarboxylic acids such as succinic acid substituted with a group or an alkenyl group having 2 or more and 20 or less carbon atoms.

As the carboxylic acid component, terephthalic acid or 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. The content of terephthalic acid or fumaric acid in the carboxylic acid component is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, still more preferably 90 mol% or more, still more preferably 95. More than mol%, more preferably 100 mol%. When terephthalic acid and fumaric acid are used in combination, the total content of both is preferably within the above range.

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, still more preferably 8 or more and 12 or less carbon atoms, and further. 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.

From the viewpoint of hot offset resistance, the content of the trivalent or higher carboxylic acid compound is preferably 1 mol% or more, more preferably 2 mol% or more, still more preferably 3 mol% or more in the carboxylic acid component. , And preferably 30 mol% or less, more preferably 25 mol% or less, still more preferably 20 mol% or less, still more preferably 10 mol% or less.

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, more preferably 1.05 or less.

The polyester resin preferably contains, 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, or the like. It can be produced by polycondensation at a temperature of 130 ° C. or higher, more preferably 170 ° C. or higher, and preferably 250 ° C. or lower, more preferably 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 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 85 ° C. or higher, more preferably 90 ° 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, it is preferably 130 ° C. or lower, more preferably 120 ° C. or lower, and further preferably 110 ° C. or lower.

The glass transition temperature of the polyester resin is preferably 45 ° C. or higher, more preferably 50 ° C. or higher, and from the viewpoint of improving the low temperature fixability, from the viewpoint of improving the dispersion stability of the toner particles and improving the storage stability. Therefore, it is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, and further preferably 60 ° C. or lower.

The acid value of the polyester resin is preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more from the viewpoint of adsorption of the dispersant to the toner particles, and preferably from the viewpoint of dispersion stability of the toner particles. It is 60 mgKOH / g or less, more preferably 40 mgKOH / g or less.

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 the polyester resin include polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, and the like. Styrene-based resin, epoxy-based resin, rosin-modified maleic acid resin, polyethylene, which are homopolymers or copolymers containing styrene or styrene-substituted products such as styrene-acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers. One or more selected from resins such as styrene resins, polypropylene resins, styrene resins, silicone resins, phenol resins, aliphatic or alicyclic hydrocarbon resins 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, or 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, etc. is mixed in advance with a mixer such as a Henschel mixer, a super mixer, a ball mill, etc., 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, the high temperature heating roll is the high rotation side roll and the low temperature cooling roll is the low rotation from the viewpoint of improving the fixability of the liquid developer. 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, a mechanical type mill and the like.

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, 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 terpene compound in the present invention has a predetermined molecular weight. The molecular weight of the terpene compound is 210 or less, more preferably 200 or less, and from the viewpoint of low temperature fixability, it is 100 or more, preferably 130 or more, and more preferably 150 or more.

Terpene compounds are classified into monoterpene compounds which are dimers of isoprene, sesquiterpene compounds which are trimerics, diterpene compounds which are tetramers, and the like, and monoterpene compounds are preferable in the present invention.

Examples of the terpene compound include terpene hydrocarbons, terpene alcohols, terpene ethers, terpene esters, terpene aldehydes, terpene ketones, terpene oxides, terpene carboxylic acids and the like having a predetermined molecular weight. ..

Examples of terpene hydrocarbons include myrcene, osimene, limonene, terpinolene, terpinene, phellandrene, silvestrene, sabinene, kalen, pinene, camphene, tricyclene, fencan, p-mentane, pinene and the like, which have a predetermined molecular weight. ..

Examples of terpene alcohols include citronellol, geraniol, nerol, linalool, menthol, terpineol, carpeol, twill alcohol, pinocampeol, fentyl alcohol, porneol, α-terpineol, dihydrotapineol and the like having a predetermined molecular weight. Can be mentioned.

Examples of terpene ethers include ethers of terpene alcohols such as tarpinyl methyl ether having a predetermined molecular weight.

Examples of terpene esters include acetylated terpene alcohols such as dihydrocarbyl acetate, calvir acetate, isobonyl acetate and dihydroterpinyl acetate having a predetermined molecular weight.

Examples of terpene aldehydes include citronellal, citral, cyclocitral, safranal, ferlandral, perillaldehyde and the like having a predetermined molecular weight.

Examples of terpene ketones include Dageton, Ionone, Yiren, Menthone, Carbomenton, Carbotanaseton, Piperitenone, Thujone, Karon, Camphor and the like having a predetermined molecular weight.

Examples of terpene oxides include cineole, pinole, ascaridole and the like having a predetermined molecular weight.

Examples of terpene carboxylic acids include citronellic acid, hinoki cypress acid, and santalic acid, which have a predetermined molecular weight.

Among these terpene compounds, an etherified product of terpene alcohol or an acetylated product of terpene alcohol is preferable.

The content of the terpene compound is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, still more preferably 1 part by mass or more, and preferably 15 parts by mass or less with respect to 100 parts by mass of the toner particles. , More preferably 10 parts by mass or less, still more preferably 5 parts by mass or less.

The dispersant in the present invention is preferably a basic dispersant having a basic nitrogen-containing group from the viewpoint of high adsorptivity to a resin having an acidic group. The basic nitrogen-containing group includes an amino group (-NH ₂ , -NHR, -NHRR'), an amide group (-C (= O) -NRR'), an imide group (-N (COR) ₂ ), and a nitro group. From the group consisting of _{(-NO 2} ), imino group (= NH), cyano group (-CN), azo group (-N = N-), diazo group (= N ₂ ), and azi group (-N ₃₎ At least one selected is preferred. Here, R and R'represent a hydrocarbon group having 1 to 5 carbon atoms. From the viewpoint of the adsorptivity of the dispersant to the toner particles, the amino group and / or the imino group is preferable, and from the viewpoint of the chargeability of the toner particles, the imino group is more preferable.

Examples of the functional group contained in addition to the basic nitrogen-containing group include a hydroxy group, a formyl group, an acetal group, an oxime group, a thiol group and the like.

From the viewpoint of dispersion stability, the proportion of the basic nitrogen-containing group in the basic dispersant is preferably 70% by number or more, more preferably 80% by number or more, and further preferably 90% by number in terms of the number of heteroatoms. The above is more preferably 95% by number or more, still more preferably 100% by number.

From the viewpoint of dispersibility of the liquid developer, the basic dispersant is a hydrocarbon having 16 or more carbon atoms, a hydrocarbon having 16 or more carbon atoms partially substituted with a halogen atom, and 16 carbon atoms having a reactive functional group. The above hydrocarbons, polymers of hydroxycarboxylic acids with 16 or more carbon atoms, polymers of dibasic acids with 2 or more and 22 or less carbon atoms and diols with 2 or more and 22 or less carbon atoms, alkyl (meth) acrylates with 16 or more carbon atoms. It is preferable that it contains a group derived from the polymer, polyolefin, etc. (hereinafter, also referred to as “dispersible group”).

As the hydrocarbon having 16 or more carbon atoms, a hydrocarbon having 16 or more carbon atoms and 24 or less carbon atoms is preferable, and examples thereof include hexadecene, octadecene, icosane, and docosane.

As the hydrocarbon having 16 or more carbon atoms partially substituted with a halogen atom, a hydrocarbon having 16 to 24 carbon atoms partially substituted with a halogen atom is preferable, and for example, chlorohexadecane, bromohexadecane, chlorooctadecane, bromo Examples thereof include octadecane, chloroeikosan, bromoeikosan, chlorodocane, bromodokosan and the like.

As the hydrocarbon having a reactive functional group and having 16 or more carbon atoms, a hydrocarbon having a reactive functional group and having 16 or more and 24 or less carbon atoms is preferable, and for example, hexadecenyl succinic acid and octadecenyl succinic acid. Examples thereof include acids, eicosenyl succinic acid, docosenyl succinic acid, hexadecyl glycidyl ether, octadecyl glycidyl ether, eicosyl glycidyl ether, docosyl glycidyl ether and the like.

As the polymer of the hydroxycarboxylic acid having 16 or more carbon atoms, the polymer of the hydroxycarboxylic acid having 16 or more carbon atoms and 24 or less carbon atoms is preferable, and examples thereof include a polymer of 18-hydroxystearic acid.

Examples of the polymer of a dibasic acid having 2 to 22 carbon atoms and a diol having 2 to 22 carbon atoms include a polymer of ethylene glycol and sebacic acid, a polymer of 1,4-butanediol and fumaric acid, 1 , 6-Hexanediol and fumaric acid polymer, 1,10-decanediol and sebacic acid polymer, 1,12-dodecanediol and 1,12-dodecanedioic acid polymer and the like.

As the polymer of alkyl (meth) acrylate having 16 or more carbon atoms, a polymer of alkyl (meth) acrylate having 16 or more carbon atoms and 24 or less carbon atoms is preferable, for example, a polymer of hexadecyl methacrylate, a polymer of octadecyl methacrylate, and doco. Examples thereof include polymers of sill methacrylate.

Examples of the polyolefin include polyethylene, polypropylene, polybutylene, polyisobutene, polymethylpentene, polytetradecene, polyhexadecene, polyoctadecene, polyeicosene, polydocene and the like.

The basic dispersant preferably has a polyolefin skeleton from the viewpoint of dispersibility of the toner particles, more preferably has a polypropylene skeleton and / or a polyisobutene skeleton, and has a polyisobutene skeleton from the viewpoint of increasing the melting point of the dispersant. It is more preferable to have. Therefore, among the dispersible groups, a group derived from polyolefin is preferable, a group derived from polypropylene and / or a group derived from polyisobutene is more preferable, and a group derived from polyisobutene is further preferable.

The basic dispersant is not particularly limited, but is obtained, for example, by reacting a basic nitrogen-containing group raw material with a dispersible group raw material.

Examples of the basic nitrogen-containing group raw material include polyalkyleneimine such as polyethyleneimine, polyallylamine, and polyaminoalkylmethacrylate such as polydimethylaminoethylmethacrylate.

The number average molecular weight of the basic nitrogen-containing group raw material is preferably 100 or more, more preferably 500 or more, still more preferably 1,000 or more, and the dispersion of toner particles, from the viewpoint of the adsorptivity of the acidic group to the resin. From the viewpoint of sex, it is preferably 15,000 or less, more preferably 10,000 or less, still more preferably 5,000 or less.

Dispersible group raw materials include halogenated hydrocarbons having 16 or more carbon atoms, hydrocarbons having a reactive functional group having 16 or more carbon atoms, polymers of hydroxycarboxylic acids having 16 or more carbon atoms, and 2 or more carbon atoms. Polymers of dibasic acid with 22 or less and diols with 2 or more carbon atoms and 22 or less, alkyl (meth) acrylate polymers with 16 or more carbon atoms having reactive functional groups, polyolefins with reactive functional groups, etc. Can be mentioned. Among these, from the viewpoint of availability of raw materials and reactivity, halogenated hydrocarbons having 16 or more carbon atoms, hydrocarbons having a reactive functional group having 16 or more carbon atoms, and reactive functional groups are provided. A polymer of an alkyl (meth) acrylate having 16 to 24 carbon atoms or a polyolefin having a reactive functional group is preferable. 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, as the compound having a reactive functional group, a carboxylic acid-based compound is preferable. Carboxylic acid compounds include fumaric acid, maleic acid, ethane acid, propanoic acid, butanoic acid, succinic acid, oxalic acid, malonic acid, tartaric acid, their anhydrides, or alkyl esters having 1 to 3 carbon atoms. And so on. Specific examples of the dispersible group raw material include halogenated alkanes such as chlorooctadecan, epoxy-modified polyoctadecyl methacrylate, polyethylene succinic anhydride, chlorinated polypropylene, polypropylene succinic anhydride, polyisobutene succinic anhydride and the like.

The content of the compound having a polyolefin skeleton in the dispersible base raw material 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 90% by mass or more, from the viewpoint of dispersibility of the toner particles. It is 100% by mass.

From the viewpoint of the dispersibility of the toner particles, the number average molecular weight of the dispersible group raw material is preferably 500 or more, more preferably 700 or more, still more preferably 900 or more, and the adsorptivity of the dispersant to the toner particles. From the viewpoint, it is preferably 5,000 or less, more preferably 4,000 or less, and further preferably 3,000 or less.

The mass ratio of the basic nitrogen-containing group to the dispersible group (basic nitrogen-containing group / dispersible group) in the reaction product X is preferably 3/97 or more, more preferably 3/97 or more, from the viewpoint of adsorptivity to toner particles. Is 5/95 or more, and is preferably 20/80 or less, more preferably 15/85 or less, from the viewpoint of dispersion stability of toner particles. The mass ratio of the basic nitrogen-containing group to the dispersible group in the reactant X can be measured by NMR of the reactant X, but the production of the reactant X in which the basic nitrogen-containing group raw material and the dispersible group raw material are reacted with each other. In, the mass ratio of the reacted raw material compound can also be regarded as the mass ratio of the basic nitrogen-containing group and the dispersible group in the dispersant (basic nitrogen-containing group / dispersible group).

Other basic dispersants include monomer A having an amino group and formula (II):

(In the formula, R ¹ indicates a hydrogen atom or a methyl group, and R ² indicates an alkyl group having 1 to 22 carbon atoms or an alkenyl group having 2 to 22 carbon atoms, which may have a substituent).
Examples thereof include a copolymer C with the monomer B represented by.

As the monomer A having an amino group, the formula (III):
CH ₂ = C (R ⁵ ) COYR ⁶ NR ³ R ⁴ (III)
(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or a linear or branched alkyl group having 1 or more and 4 or less carbon atoms, and they are bonded to each other to form a ring structure. R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents a linear or branched alkylene group having 2 to 4 carbon atoms, and Y represents -O- or -NH-).
A monomer having an amino group represented by, or an acid neutralized product (tertiary amine salt) or a quaternary ammonium salt of this monomer is preferable. Preferred acids for obtaining the above acid neutralized products include hydrochloric acid, sulfuric acid, nitrate, acetic acid, formic acid, maleic acid, fumaric acid, citric acid, succinic acid, adipic acid, sulfamic acid, toluenesulfonic acid, lactic acid, pyrrolidone-. Examples include 2-carboxylic acid and succinic acid. Preferred quaternary agents for obtaining the above quaternary ammonium salt include alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide, dimethyl sulfate, diethyl sulfate, di-n-propyl sulfate and the like. General alkylating agents of.

In the formula (III), R ³ and R ⁴ are each independently preferably a linear or branched alkyl group having 1 or more and 4 or less carbon atoms, and NR ³ R ⁴ is preferably a tertiary amino group. Specific examples of R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, an isopropyl group and the like, and a methyl group is preferable.

Examples of R ⁶ include an ethylene group, a propylene group, a butylene group and the like, and an ethylene group is preferable.

^{Specific examples of the monomer in which NR 3} R ⁴ is a tertiary amino group in the formula (III) (monomer having a tertiary amino group) include a (meth) acrylate having a dialkylamino group and a dialkylamino group ( Meta) acrylamide and the like can be mentioned. In addition, "(meth) acrylic acid ester" indicates that the case of acrylic acid ester and methacrylic acid ester, and "(meth) acrylamide" indicates the case of both acrylamide and methacrylamide.

Examples of the (meth) acrylic acid ester having a dialkylamino group include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, diisopropylaminoethyl (meth) acrylate, and dibutylaminoethyl (dibutylaminoethyl). Examples thereof include one or more selected from the group consisting of meta) acrylate, diisobutylaminoethyl (meth) acrylate, and dit-butylaminoethyl (meth) acrylate.

Examples of (meth) acrylamide having a dialkylamino group include dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, diisopropylaminopropyl (meth) acrylamide, and dibutylaminopropyl (meth). Examples thereof include one or more selected from the group consisting of acrylamide, diisobutylaminopropyl (meth) acrylamide, and dit-butylaminopropyl (meth) acrylamide.

Among these, (meth) acrylic acid ester having a dialkylamino group is preferable from the viewpoint of small particle size, low viscosity, storage stability, and low temperature fixability, and dimethylaminoethyl (meth) acrylate is more preferable.

The monomer B is represented by the above formula (II), and in the above formula (II), the carbon number of the alkyl group and the alkenyl group represented by ^{R 2 is low viscosity, storage stability, and low temperature.} From the viewpoint of fixability, it is preferably 10 or more, more preferably 12 or more, and from the viewpoint of low temperature fixability, it is 22 or less, preferably 18 or less, more preferably 16 or less, and further preferably 14 or less. The alkyl group or alkenyl group of R ² may be a straight chain or a branched chain, and may have a substituent such as a hydroxyl group.

Therefore, ^{it is preferable that the monomer B contains at least the monomer B2 in which R 2} is an alkyl group or an alkenyl group having 10 or more and 22 or less carbon atoms.

In the monomer B, R ² is a monomer B1 which is an alkyl group having 1 or more and 9 or less carbon atoms or an alkenyl group having 2 or more and 9 carbon atoms or less, and a monomer B2 which is an alkyl group or an alkenyl group having 10 or more and 22 carbon atoms or less. The molar ratio (monomer B1 / monomer B2) of (monomer B1 / monomer B2) is 0.1 or less, preferably 0.07 or less, more preferably 0.05 or less, still more preferably 0.03 or less, still more preferably, from the viewpoint of low viscosity, storage stability, and low-temperature fixability. Is 0.01 or less, 0 or more, and preferably 0.

Specific examples of monomer B include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, and the like. 2-Ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) nonyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) undecyl (meth) acrylate, (iso) dodecyl (meth) ) Acrylate, (iso) tridecyl (meth) acrylate, (iso) tetradecyl (meth) acrylate, (iso) pentadecyl (meth) acrylate, (iso) hexadecyl (meth) acrylate, (iso) heptadecyl (meth) acrylate, (iso) ) Octadecyl (meth) acrylate, (iso) nonadecil (meth) acrylate, (iso) icosyl (meth) acrylate, (iso) eicosyl (meth) acrylate, (iso) henicocil (meth) acrylate, (iso) docosyl (meth) Examples include acrylate. One or more of these can be used. Here, "(iso or tertiary)" and "(iso)" mean that both the case where these groups are present and the case where they are not present are included, and when these groups are not present. Indicates that it is normal. Further, "(meth) acrylate" indicates that the case of both acrylate and methacrylate is included.

The molar ratio of monomer A to monomer B (monomer A / monomer B) functions as a dispersant, and from the viewpoint of low viscosity and storage stability, it is 2/98 or more, preferably 3/97 or more, more preferably 5 / 95 or more, more preferably 7/93 or more, and from the viewpoint of low viscosity, storage stability, and low temperature fixability, 50/50 or less, preferably 40/60 or less, more preferably 35/65 or less, It is more preferably 25/75 or less, still more preferably 20/80 or less.

The total content of monomer A and monomer B in all the monomers used in the copolymer C is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and preferably 100% by mass or more. It is 100% by mass or less, more preferably 100% by mass.

The polymerization of Monomer A and Monomer B is carried out by heating to about 40 to 140 ° C. in a solvent in the presence of a polymerization initiator such as 2,2'-azobis (2,4-dimethylvaleronitrile). Can be made to.

The weight average molecular weight of the basic dispersant is preferably 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more from the viewpoint of low viscosity and low temperature fixability, and preferably 100,000 or more from the same viewpoint. Below, it is more preferably 50,000 or less, still more preferably 30,000 or less.

The number average molecular weight of the basic dispersant is preferably 2,000 or more, more preferably 2,500 or more, still more preferably 3,000 or more, still more preferably 3,500 or more, from the viewpoint of low viscosity and low temperature fixability. From the same viewpoint, it is preferably 10,000 or less, more preferably 9,000 or less, still more preferably 8,000 or less.

The content of the basic dispersant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 2 parts 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 the chargeability of the toner, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 5 parts by mass or less.

The liquid developer of the present invention may contain a known dispersant other than the basic dispersant, but the content of the basic dispersant is preferably 50% by mass or more in the dispersant. More preferably 70% by mass or more, further preferably 90% by mass or more, still more preferably 95% by mass or more, preferably 100% by mass or less, more preferably substantially 100% by mass, still more preferably 100% by mass. is there.

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.

The insulating liquid in the liquid developer of the present invention is preferably an insulating liquid containing 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, still more preferably 3 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.

The boiling point of polyisobutene is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, further preferably 160 ° C. or higher, and a liquid, from the viewpoint of further improving the dispersion stability of the toner particles and improving the storage stability. From the viewpoint of further improving the low-temperature fixability of the developer and from the viewpoint of further improving the grindability of the toner during wet grinding to obtain a liquid developer having a small particle size, it is preferably 300 ° C. or lower, more preferably 280 ° C. or lower, and further. It is preferably 260 ° C. or lower.

The content of polyisobutene 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 in the insulating liquid from the viewpoint of suppressing charger contamination. It is more preferably 80% by mass or more, still more preferably 90% by mass or more.

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.

Specific examples other than polyisobutene include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes, vegetable oils, and the like.

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, and from the viewpoint of further improving the dispersion stability of the toner particles and improving the storage stability, and From the viewpoint of further improving the low-temperature fixability of the toner and further improving the grindability of the toner during wet grinding to obtain toner particles having a small particle size, the temperature is preferably 300 ° C. or lower, more preferably 280 ° C. or lower, still more preferable. Is below 260 ° C. 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, and preferably 100 mPa, from the viewpoint of improving the developability and the storage stability of the toner particles in the liquid developer. -S or less, more preferably 50 mPa · s or less, still more 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, terpene compounds, dispersants, and insulating liquids, liquid developers include mold release agents, charge control agents, charge control resins, magnetic powders, fluidity improvers, and conductivity adjustments. Additives such as an agent, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver may be appropriately contained.

The liquid developer is obtained by dispersing toner particles and a terpene compound 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, the toner particles and the terpene compound can be dispersed in an insulating liquid and then wet-ground to obtain a liquid developer. preferable.

As a method for mixing the toner particles, the dispersant, the terpene compound, and the insulating liquid, a method of stirring with a stirring mixer 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 stable dispersion of toner particles. 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 to be used, the peripheral speed of the rotor, the residence time, and the like.

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 μm or more, still more preferably 1.5 μm or more, from the viewpoint of reducing the viscosity of the liquid developer. 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.

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. 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: To 100 mL of the electrolytic solution, add the sample dispersion 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 basic nitrogen-containing raw materials]
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 the sample 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. 100 μL of the sample solution is injected therein and measurement is performed. 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 (Mw 5.9 x 10 ³ ), P-50 (Mw 4.73 x 10 ⁴ ), P-200 (Mw 2.12 x 10) manufactured by Showa Denko KK. ⁵ ), P-800 (Mw 7.08 × 10 ⁵ )) prepared as a standard sample is used. 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 of dispersible group raw materials]
(1) The dispersible group raw material was dissolved in tetrahydrofuran so that the prepared concentration of the sample solution 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. 100 μL of the sample solution is injected therein and measurement is performed. 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 monodisperse polystyrene (A-500 (Mw 5.0 x 10 ² ), A-1000 (Mw 1.01 x 10 ³ ), A-2500 (Mw 2.63 x 10 ³ ) manufactured by Tosoh Corporation). , 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 x 10 ⁴ ), F-20 (Mw 1.90 x 10 ⁵ ), F-40 (Mw 4.27 x 10 ⁵ ), F-80 (Mw 7.06 x 10 ⁵ ), F-128 (Mw 1.09 x 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)

[Number average molecular weight and weight average molecular weight of dispersant]
The molecular weight distribution is measured by gel permeation chromatography (GPC) by the following method, and the number average molecular weight and the weight average molecular weight (Mw) are determined.
(1) Preparation of sample solution The dispersant (the insulating liquid was distilled off from the dispersant solution) 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) Measurement of molecular weight distribution Using the following measuring device and analytical column, flow tetrahydrofuran as an eluent at a flow rate of 1 mL per minute to stabilize the column in a constant temperature bath at 40 ° C. 100 μL of the sample solution is injected therein and measurement is performed. 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 monodisperse polystyrene (A-500 (5.0 x 10 ² ), A-1000 (1.01 x 10 ³ ), A-2500 (2.63 x 10 ³ ), manufactured by Toso Co., Ltd.). A-5000 (5.97 × 10 ³ ), F-1 (1.02 × 10 ⁴ ), F-2 (1.81 × 10 ⁴ ), F-4 (3.97 × 10 ⁴ ), F-10 (9.64 × 10 ⁴ ), Use F-20 (1.90 × 10 ⁵ ), F-40 (4.27 × 10 ⁵ ), F-80 (7.06 × 10 ⁵ ), F-128 (1.09 × 10 ⁶ )) as standard samples. The molecular weight is shown in parentheses.
Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation)
Analytical column: TSKgel GMH _XL + TSKgel G3000H _XL (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 size (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]
The raw material monomers of the polyester resin shown in Table 1, the esterification catalyst, and the polymerization inhibitor were placed in a 10 L four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and used with a mantle heater. The temperature is raised from 180 ° C. to 210 ° C. over 4 hours, the reaction is carried out at 210 ° C. for 4 hours, and the reaction is further carried out at 8.3 kPa until the softening point shown in Table 1 is reached. A resin (resin A) was obtained.

Resin Production Example 2 [Resin B]
The polyester resin raw material monomer and esterification catalyst shown in Table 1 are mixed with a nitrogen introduction tube, a dehydration tube equipped with a fractional distillation tube through which hot water at 98 ° C is passed, a stirrer, and a 10 L four-necked flask equipped with a thermocouple. I put it in. After raising the temperature to 180 ° C., the temperature was raised to 210 ° C. over 5 hours, and the reaction was carried out until the reaction rate reached 90%. Further, the reaction was carried out at 8.3 kPa, and when the target softening point was reached, the reaction was terminated to obtain a polyester resin (resin B) having the physical characteristics shown in Table 1. In the resin production example, the reaction rate means a value of the amount of produced reaction water (mol) / the theoretical amount of produced water (mol) × 100.

Resin Production Example 3 [Resin C]
1567 g of xylene was placed in a 5 L four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and the temperature was raised to 130 ° C. The mixed solution of the raw material monomer of the styrene resin and the polymerization initiator shown in Table 1 was added dropwise at 130 ° C. over 1.5 hours while stirring, and the addition polymerization reaction was carried out while maintaining the same temperature for another 1.5 hours. The temperature was raised to 160 ° C. and the reaction was carried out for 1 hour, then the temperature was raised to 200 ° C. and held for 1 hour to remove xylene. Further, the remaining xylene was removed at 8.3 kPa to obtain a styrene acrylic resin (resin C) having the physical characteristics shown in Table 1.

Dispersant Production Example 1
The basic nitrogen-containing base material 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. While stirring, a solution of polyisobutene succinic anhydride (PIBSA) (OLOA15500, manufactured by Chevron Japan Co., Ltd., effective content: 78% by mass) shown in Table 2 as a dispersible base material in xylene was dissolved in xylene at 25 ° C. for 1 hour. And dropped. After completion of the dropping, the temperature was maintained at 25 ° C. 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. Xylene was distilled off by reducing the pressure to 8.3 kPa at 160 ° C., and the time when the peak of acid anhydride derived from PIBSA (1780 cm ^-1 ) disappeared from the IR analysis and the peak derived from imide bond (1700 cm ^-1 ) occurred. As the reaction end point, a dispersant A having the physical properties shown in Table 2 was obtained.

Dispersant Production Example 2
100 g of a solvent (methyl ethyl ketone) was placed in a 2 L four-necked flask equipped with a cooling tube, a nitrogen introduction tube, a stirrer and a thermocouple, and the inside of the reaction vessel was replaced with nitrogen gas. The inside of the reaction vessel was heated to 80 ° C., and the mixture of the raw material monomer and the polymerization initiator shown in Table 3 was added dropwise over 2 hours to carry out the polymerization reaction. After completion of the dropping, the reaction was carried out at 80 ° C. for another 3 hours. The solvent was distilled off at 80 ° C. to obtain a dispersant B composed of a copolymer having the physical characteristics shown in Table 3.

Examples 1 to 5 and Comparative Examples 4 to 5 (Examples 1 and 2 are reference examples)
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 4 in advance using a 20 L Henschel mixer. After stirring and mixing at a frequency of 1500 r / min (peripheral speed 21.6 m / sec) for 3 minutes, the mixture was melt-kneaded 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 obtained kneaded product 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, conductivity: 1.52 x 10 ^-12 S / m, boiling point: 247 ° C, viscosity at 25 ° C: 2 mPa・ S) Put 62.2 parts by mass, 1.75 parts by mass of the terpene compound shown in Table 4 and 1.05 parts by mass of the dispersant in a 1 L volume polyethylene container, and use "TK Robomix" (manufactured by Primix Co., Ltd.). Then, 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 4 was reached.} After removing the beads by filtration, 44 parts by mass of the insulating liquid "NAS-4" (manufactured by Nichiyu Co., Ltd.) was added to 100 parts by mass of the filtrate to dilute it, and the solid content concentration was 25% by mass. A liquid developer having the physical properties shown in 4 was obtained.

Comparative Examples 1 to 3
Except that the resin shown in Table 4 was used as the binder resin in the preparation of the toner particles, the terpene compound was not used in the preparation of the toner particle dispersion liquid, and the amount of the insulating liquid used was changed to 63.95 parts by mass. , A liquid developer was obtained in the same manner as in Example 1.

Test Example 1 [Low temperature fixability]
A liquid developer is dropped on "OK top coated paper" (manufactured by Oji Paper Co., Ltd., basis weight: 127.9 g / m ² , paper thickness: approx. 103 μm), and the toner mass after drying with a wire bar is 3.4 g / m. ^A thin film was prepared so as to be 2. Then, it was kept in a constant temperature bath at 80 ° C. for 10 seconds.

Subsequently, using a fixing machine taken out from "OKI MICROLINE 3010" (manufactured by Oki Data Corporation), the fixing process was performed at a fixing roll temperature of 80 ° C. and a fixing speed of 280 mm / sec. Then, while raising the fixing roll temperature to 160 ° C. by 10 ° C., the fixing treatment was performed in the same manner, and a fixing image was obtained at each temperature.

Attach the mending tape "Scotch Mending Tape 810" (manufactured by 3M Japan Ltd., width 18 mm) to the obtained fixed image, apply pressure to the tape with a roller so that a load of 500 g is applied, and then apply the tape. It peeled off. The image densities before and after the tape peeling were measured using a colorimeter "Gretag Macbeth Spectroeye" (manufactured by Gretag). The image print portion was measured at 3 points each, and the average value was calculated as the image density. The fixing rate (%) is calculated from the value of image density after peeling / image density before peeling x 100, and the lowest temperature in the temperature range where the fixing rate is 90% or more and no offset occurs is defined as the minimum fixing temperature. did. The results are shown in Table 4. It is shown that the lower the minimum fixing temperature, the better the low temperature fixing property.

Test Example 2 [Document offset resistance]
^{In Test Example 1, a load of 80 g / cm 2} was applied to a stack of two sheets of paper so that the fixed image portions fixed at 140 ° C were opposed to each other, and the mixture was allowed to stand still for one day in an environment at a temperature of 50 ° C. I put it. Then, the stacked papers were taken out and peeled off. The state of the fixed image portion was visually observed, and the document offset resistance was evaluated according to the following evaluation criteria. The results are shown in Table 4.

〔Evaluation criteria〕
A: There is no peeling sound at the time of peeling, and no image loss is seen. B: There is a peeling sound at the time of peeling, but no image loss is seen. C: There is a peeling sound at the time of peeling, and minute image loss is seen. D: There is a peeling sound at the time of peeling, and a large image defect is seen. E: It is fused and cannot be peeled.

From the above results, it can be seen that the liquid developing agents of Examples 1 to 5 are superior in both low temperature fixability and document offset resistance as compared with the liquid developing agents of Comparative Examples 1 to 5.
On the other hand, the liquid developing agents of Comparative Examples 1 and 2 that do not contain the terpene compound lack low-temperature fixability, and even if they contain the terpene compound, their molecular weight is too large in Comparative Example 5. The liquid developer has improved low-temperature fixability, but lacks document offset resistance. Further, as compared with Comparative Examples 3 and 4, when a styrene acrylic resin is used as the binder resin, the low temperature fixability is improved but the document offset resistance is lowered by blending the terpene compound, which is different from that of the polyester resin. The result is exactly the opposite. Further, the particle size of the toner particles in the liquid developer of Comparative Examples 3 and 4 is large, but this is because the styrene acrylic resin does not have an acid group, so that the dispersant is not easily adsorbed and the grindability is high. It is presumed that it has deteriorated.

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 (3)

A liquid developer containing toner particles containing a binder resin and a colorant, a terpene compound, a dispersant, and an insulating liquid, wherein the binder resin contains a polyester resin and the molecular weight of the terpene compound. There Ri der 100 or 210 or less, the terpene compound, you containing etherified or acetylated terpene alcohol terpene alcohol, the liquid developer. The liquid developer according to claim 1, wherein the polyester resin is a polycondensate of an alcohol component containing an aliphatic diol and a carboxylic acid component. The liquid developer according to claim 1 or 2, wherein the content of the terpene compound is 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner particles.