JP2000010340A - Electrophotographic toner and electrophotographic liquid developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner and an electrophotographic liquid developer being safe to an environment and capable developing at a high speed by imparting sufficient electric chargeability to a toner in an yellow electrophotographic toner and an yellow electrophotographic liquid developer capable of coping with the formation of a full color image. SOLUTION: (1) In a toner mainly composed of a coloring agent and a binder resin, an electrophotographic toner contains a compound classified into PY180 as a coloring agent and/or the derivative, and contains the binder resin having an acid value of 10 mgKOH/g to 100 mgKOH/g. (2) an electrophotographic liquid developer is formed by dispersing the toner in an electrically insulating carrier liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner and an electrophotographic liquid developer used for developing an electrostatic latent image in an image forming apparatus such as an electrophotographic copying machine or a printer. In particular, the present invention relates to a yellow electrophotographic toner and an electrophotographic liquid developer.

[0002]

2. Description of the Related Art Conventionally, offset printing has been used as a method for creating and copying a high definition and beautiful full color image. Offset printing is suitable for large-volume printing because high-quality images can be obtained at high speed and at low cost, but maintenance and operation of the apparatus are difficult.

[0003] On the other hand, with the spread of personal computers and the like, it has been required that full-color images can be created and copied with simple operations, and that many types of images can be created in small numbers. In this regard, it can be said that electrophotographic copying machines, printers and the like are preferable because the unit price per part hardly changes regardless of whether the number of copies is large or small. Also, compared to other inkjet printers, etc.
Excellent in printing speed, reproducibility and durability.

[0004] In electrophotographic image formation, development methods are classified into dry development methods and wet development methods. In the dry development method, a toner (colored fine particles) or a toner to which a carrier having magnetism or the like is added is used as a developer. Dry toners used in dry development cannot be so fine because they may escape into the surrounding atmosphere and float in the air, and usually have an average particle size of about 10 μm or less. Relatively large ones are used. Since the dry toner has such a relatively large particle diameter, the resolution in development is not so high.

[0005] On the other hand, in the wet development method, the mainstream of practical use as a developer at present is a toner containing a colorant and a binder resin as main components, a charge control agent and a toner in an electrically insulating carrier liquid. This is a liquid developer in which a dispersion stabilizer or the like is dispersed. It is considered that the charging of the toner is due to the adsorption of ions derived from the charge control agent, and the charged toner is subjected to development by the principle of electrophoresis. Since the toner used in the wet development does not escape into the atmosphere, it can be made finer, and a toner having an average particle size in the submicron range is also practical. Thus, there is an advantage that an image having high resolution and excellent gradation can be obtained.

The demand for the image quality of full-color images is increasing year by year, and in order to obtain high image quality equivalent to or higher than that of offset printing, a wet process using a toner having a small particle diameter and high chargeability is required. It is appropriate to use a developing method. In forming a full-color image, generally, yellow, magenta, cyan,
Using four color developers, the images formed with the respective color developers are superposed by the subtractive color mixture method. In the case of a dry developer, these four-color developers are obtained by dispersing and mixing pigments and dyes that form each color and various additives as needed in a binder resin to obtain a toner having a predetermined particle size. Also,
The liquid developer is obtained by dispersing the toner thus obtained in a carrier liquid.

[0007] Among the toners of each color, the yellow toner is a color index pigment yellow (hereinafter abbreviated as "PY") 12, PY13, PY17, PY174, PY, which is a pigment widely used in conventional printing inks and the like.
Y176 and the like are preferable in terms of coloring property, cost, and the like.
Often used. However, the yellow pigment contains organically bound chlorine and heavy metals in the molecule. Therefore, PY, which is an azo-based compound that does not contain organically-bound chlorine or heavy metals and exhibits color development comparable to that of the conventional yellow pigment,
The use of 180 has been proposed. PY180 is Novope
Rum-Gelb P-HG, Toner Yellow HG An azo pigment known under the trade name of VP2155 and the like, and PY180 or a dry toner containing the same is disclosed in U.S. Pat. No. 4,870,164, U.S. Pat. It is disclosed in gazettes and the like.

[0008]

However, the above P
When a compound classified as Y180 and / or a derivative thereof is used as a colorant of a toner subjected to dry development or a colorant of a toner in a liquid developer, the chargeability is higher than that of a toner using a conventional yellow pigment. It is difficult to obtain a high developing speed required for practical use. In order to obtain a high-definition image, the toner particle size must be reduced. In this case, a higher toner chargeability is required to obtain a desired development speed. Also, the toner using a derivative thereof and / or a derivative thereof as a coloring agent has a disadvantage that a high-definition image cannot be obtained due to relatively low chargeability.

Accordingly, the present invention provides a yellow electrophotographic toner and a yellow electrophotographic liquid developer capable of forming a full-color image, which are safe for the environment and have sufficient chargeability. Accordingly, it is an object of the present invention to provide an electrophotographic toner and an electrophotographic liquid developer capable of performing high-speed development.

[0010]

It is known that the chargeability of a toner is greatly affected by the surface characteristics (such as the type of functional group) of the toner. Based on this point, the present inventor has conducted various studies in order to solve the above-mentioned problems, and has found that a desired developing speed can be achieved by adjusting the acid value of the binder resin.

Based on the above findings, the present invention provides an electrophotographic toner comprising a colorant and a binder resin as main components,
Color Index Pigment as colorant
It contains a compound classified into Yellow 180 (Color Index Pigment Yellow 180) (hereinafter abbreviated as “PY180”) and / or a derivative thereof, and the binder resin has an acid value of 10 mgKOH /
g to 100 mgKOH / g.

Further, the present invention is an electrophotographic liquid developer in which a toner containing a colorant and a binder resin as main components is dispersed in an electrically insulating carrier liquid, wherein the toner is used as a colorant. The present invention provides a liquid developer for electrophotography, comprising a compound classified into PY180 and / or a derivative thereof, wherein the binder resin of the toner has an acid value of 10 mgKOH / g to 100 mgKOH / g.

That is, the electrophotographic liquid developer of the present invention can be regarded as a dispersion of the electrophotographic toner of the present invention in a carrier liquid.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrophotographic toner according to a preferred embodiment of the present invention is a toner containing a colorant and a binder resin as main components. Further, it includes a compound classified as PY180 and / or a derivative thereof as a coloring agent. The binder resin has an acid value of 10 mgKOH / g to 10 mgKOH / g.
0 mgKOH / g.

The acid value refers to the number of mg of potassium hydroxide required to neutralize free fatty acids contained in 1 g.
It can be measured by the IS K5400 method. An electrophotographic toner according to a preferred embodiment of the present invention includes a toner as a dry one-component developer without using a carrier, a toner of a dry two-component developer used with a solid carrier, and a liquid in which a toner is dispersed in a carrier liquid. It can be used as any toner of the developer.

The electrophotographic toner of the preferred embodiment of the present invention uses a compound classified as PY180 and / or its derivative which does not contain organically bonded chlorine or heavy metal as a colorant of the yellow toner. It is a safe thing that does not adversely affect etc. In addition, since these colorants have good coloring properties, beautiful colors can be obtained in full-color image formation.

The acid value of the binder resin is 10 mgK.
OH / g or more and the amount of free fatty acids precipitated on the toner surface is sufficient, so that sufficient toner chargeability is obtained,
As a result, a high developing speed is obtained. Further, when the acid value is 100
The reason for setting the mgKOH / g or less is that if the acid value is too high, the variation in the charge amount of the toner in a high-humidity environment may increase, and a desired developing speed may not be obtained. This is presumably because in a high-humidity environment, the amount of water absorbed in the air increases, and the physical properties of the toner surface based on free fatty acids change.

The electrophotographic toner according to a preferred embodiment of the present invention can be manufactured, for example, as follows. First,
The binder resin and the colorant are melt-kneaded to disperse the colorant in the resin. In addition, additives such as a charge imparting agent and a plasticizer may be added to the binder resin. Examples of the coloring agent include one of the compounds classified as PY180 and derivatives thereof.
Alternatively, two or more are used. Specifically, Novoperum-Gelb PH
G, Toner Yellow HG VP2155 etc. can be used. The amount of the colorant to be added varies depending on the application, the thickness of the toner layer, and the like, but may be generally about 3% by weight to 30% by weight of the binder resin. Preferably, it is about 5% by weight to 20% by weight. If the amount of the colorant is less than 3% by weight of the binder resin, a sufficient color may not be obtained, and the amount of the colorant may be 30% by weight of the binder resin.
When the amount increases, the dispersibility of the colorant in the toner deteriorates, and when the toner image transferred onto the recording material is fixed to the recording material by heat, the fixability deteriorates. There is a possibility that the speed must be reduced.

The binder resin constituting the toner particles is
Any resin having thermoplasticity may be used. Although not limited thereto, for example, a thermoplastic saturated polyester resin, a styrene-acryl copolymer resin, a styrene-acryl modified polyester resin, a polyolefin copolymer resin (especially an ethylene copolymer), an epoxy resin, and a rosin modified phenol resin And rosin-modified maleic resin, and these can be used alone or in combination. If necessary, a resin such as paraffin wax or polyolefin may be used as a release agent by blending in a range of 20% by weight or less. In any case, those having an acid value of 10 mgKOH / g to 100 mgKOH / g are used.

Among them, a thermoplastic saturated polyester resin,
Epoxy resins, styrene-acrylic resins and the like are preferably used. When used as a toner of a liquid developer described later, a thermoplastic saturated polyester resin, an ethylene-based copolymer, a styrene-acryl resin, or the like is suitably used. Although it is particularly preferable to use a thermoplastic saturated polyester resin, this is because the thermoplastic saturated polyester resin not only can change physical properties such as thermal characteristics in a wide range, but also has excellent light transmittance when obtaining a color image. This is because a beautiful color is obtained, and the resin film after fixing is tough because of excellent spreadability and viscoelasticity, and has good adhesion to a recording material such as paper.

Specifically, the thermoplastic saturated polyester resin is formed by polycondensation of a polyhydric alcohol and a polycarboxylic acid. Polyhydric alcohols include, but are not limited to, ethylene glycol, diethylene glycol,
Propylene glycol such as triethylene glycol and 1,2-propylene glycol, butanediol such as dipropylene glycol and 1,4-butanediol, alkylene glycol such as hexanediol such as neopentyl glycol and 1,6-hexanediol (fat Glycols and their alkylene oxide adducts, bisphenols such as bisphenol A and hydrogenated bisphenols and phenolic glycols of these alkylene oxide adducts, alicyclic and aromatic diols such as monocyclic or polycyclic diols, Triols such as glycerin and trimethylolpropane are exemplified. These can be used alone or in combination of two or more.

In particular, neopentyl glycol and bisphenol A alkylene oxide 2-3 mol adduct are
This is preferred in terms of the stability and cost of the product polyester resin. Examples of the alkylene oxide include ethylene oxide and propylene oxide. Examples of the polycarboxylic acid include, but are not limited to, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, phthalic acid, and modified acids thereof (for example, hexahydroanhydride). Phthalic acid),
Saturated or unsaturated dibasic basic acids such as isophthalic acid and terephthalic acid, and trifunctional or higher saturated polybasic acids such as trimellitic acid, pyromellitic acid and methylnadic acid, and acid anhydrides and lower alkyls thereof Esters and the like. These can be used alone or in combination of two or more.

In particular, isophthalic acid and terephthalic acid are preferred in view of the stability and cost of the product polyester resin. As the polycondensation method, a generally known polycondensation method can be used. Although it depends on the type of the raw material monomer, it is generally carried out at a temperature of about 150 ° C. to 300 ° C. In addition, the reaction can be performed under any conditions, such as using an inert gas as the atmosphere gas, using various solvents, and setting the pressure in the reaction vessel to normal pressure or reduced pressure. Further, an esterification catalyst may be used to promote the reaction.
As the esterification catalyst, tetrabutyl zirconate,
Zirconium naphthenate, tetrabutyl titanate,
Tetraoctyl titanate, 3/1 stannous oxalate /
Metal organic compounds such as sodium acetate can be used, but those which do not color the product ester are preferred. Further, an alkyl phosphate, an allyl phosphate, or the like may be used as a catalyst or a hue adjuster.

The acid value of the resulting polyester resin can be adjusted by controlling the mixing ratio of the polyhydric alcohol and the polycarboxylic acid and the molecular weight of the polymer. Further, the "charge imparting agent" (CCA: charge control agent) refers to an additive that is added to the inside and / or the surface of the toner and gives the toner a charge. As the charge-imparting agent, a colorless or almost colorless one generally used as a charge-imparting agent in a dry toner can be used. Although not limited thereto, for example, derivatives of salicylic acid metal salts such as zinc salicylate and chromium salicylate and complexes thereof, boron-containing salt compounds, quaternary ammonium salt compounds and the like can be used.

Examples of the plasticizer include dibutyl phthalate and diketyl phthalate. Subsequently, the thus obtained binder resin and colorant PY1
The colored kneaded product comprising a compound or the like and a charge imparting agent classified into No. 80 is roughly pulverized using a cutter mill, a hammer mill or the like, and then finely pulverized using a jet mill, a kryptron, or the like, and has a particle diameter of 6 μm to 12 μm. To the extent of toner particles.

Further, in order to improve the fluidity and the cleaning property, the toner particles obtained in this way may be made of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ) or the like. Fine powders may be added to cover the toner particles. In order to prevent the surface of the electrostatic latent image carrier from being damaged, fine powder of a fatty acid metal salt such as zinc stearate may be added. When used as a dry two-component toner, the toner is mixed with a spherical or amorphous glass having a particle size of several tens μm to several hundreds μm, or a carrier such as iron, nickel or ferrite.

Further, the liquid developer for electrophotography according to a preferred embodiment of the present invention is obtained by dispersing a toner containing a colorant and a binder resin as main components in an electrically insulating carrier liquid. Also, the toner is PY180 as a colorant.
And / or derivatives thereof. The binder resin of the toner has an acid value of 10 mg KOH.
/ G to 100 mgKOH / g.

The liquid developer for electrophotography according to a preferred embodiment of the present invention, like the toner for electrophotography, includes a compound classified as PY180 which does not contain organically bound chlorine or heavy metals as a colorant for yellow toner. Or) its safety is high because its derivatives are used. In addition, since these colorants have good coloring properties, beautiful colors can be obtained in full-color image formation.

The binder resin has an acid value of 10 mgK.
Since OH / g to 100 mgKOH / g, sufficient toner chargeability is obtained, so that a high developing speed is obtained, and fluctuation of the charge amount of the toner is suppressed even in a high humidity environment, so that a desired developing speed can be achieved. . The liquid developer for electrophotography of the preferred embodiment of the present invention can be manufactured as follows. First, the binder resin and the colorant PY18
Compounds classified as 0 and / or their derivatives are melt-kneaded to disperse the colorant in the resin. In addition, additives such as a charge imparting agent and a plasticizer may be added to the binder resin. As the binder resin, colorant, charge imparting agent, and plasticizer, those described for the electrophotographic toner can be used. The “charge imparting agent” in the liquid developer for electrophotography according to the preferred embodiment of the present invention is added to the inside and / or the surface of the toner and acts together with a charge control agent described later added to the carrier liquid to form the toner. That give high charge to Further, the charge imparting agent does not substantially elute into the carrier liquid.

Next, the thus-obtained colored kneaded product comprising the binder resin, the compound classified as PY180 as a coloring agent, and the like is coarsely pulverized using a cutter mill, a jet mill, or the like. Further, a wet grinding process is performed in a small amount of carrier liquid in which a charge control agent (CD: charge director) is dissolved, so that the particle diameter of the toner is about 0.1 μm to 10 μm, more preferably about 0.5 μm to 5 μm. To obtain a concentrated liquid developer. The concentrated liquid developer thus obtained may be diluted / dispersed with a carrier liquid containing a charge control agent until an appropriate toner concentration is obtained, if necessary.

As the carrier liquid, a liquid having a resistance value (about 10 ¹¹ to 10 ¹⁶ Ω · cm) that does not disturb the electrostatic latent image is used. At the time of development, it may be in a liquid state when the temperature is raised to a temperature higher than the softening point of the resin to be dispersed, and the state at normal temperature is not limited. Further, the boiling point is preferably such that it is easy to dry after fixing. Further, a solvent having no odor or toxicity and having a relatively high flash point is preferable.

For example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes and the like can be used. Particularly, a normal paraffin solvent and an isoparaffin solvent are preferable from the viewpoints of odor, harmlessness, and cost. Specific examples of such a solvent include No. 0 Solvent L, No. 0 Solvent M, No. 0 Solvent H (all manufactured by Nippon Petrochemical Co., Ltd.), Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, Isopar M , Isopar K, Isopar V (all manufactured by Exxon Chemical Co., Ltd.), Shellsol 71 (manufactured by Shell Petrochemical Co., Ltd.), IP Solvent 1016, IP Solvent 162
0, IP solvent 2028, IP solvent 2835
(All manufactured by Idemitsu Petrochemical Co., Ltd.), Nisseki Isosol 20
0, Nisseki Isosol 300, Nisseki Isosol 400
(Both manufactured by Nippon Oil Co., Ltd.).

The charge control agent is typically an oil-soluble ionic surfactant having an alkyl group having 20 or more carbon atoms, or a copolymer of a monomer having a nitrogen-containing group and a long-chain acrylate or methacrylate. Can be used. Examples of the oil-based ionic surfactant having an alkyl group having 20 or more carbon atoms include alkylbenzene sulfonic acid salts having an alkyl group having 20 or more carbon atoms (calcium salt, barium salt, etc.), petroleum sulfonic acid salt (barium salt, Examples thereof include calcium salts and magnesium salts), and basic petroleum sulfonic acid salts (barium salts, calcium salts, magnesium salts and the like). Particularly, petroleum sulfonates (barium salts and calcium salts) and basic petroleum sulfonates (barium salts and calcium salts) are preferable.

Such charge control agents include Sulfol Ca-45N, Sulfol Ca-45, and Sulfol 1
040, Moresco Amber SC-45N, Moresco Amber SC-45, Throughhole Ba-30N, Moresco Amber SB-50N (all manufactured by Matsumura Oil Research Co., Ltd.), Basic Barium Petronate (Basic)
Barium Petronate, Neutral Barium Petronate (Neutral Barium)
Petronate), Basic Calcium Petronate
te), neutral calcium petronate (Neu)
tral Calcium Petronate, Basic Magnesium Petronate (Basic Ma)
gnecium Petronate) (All Wi
tco Chemical Co. And the like are specific examples of products.

Examples of the copolymer of a monomer having a nitrogen-containing group and a long-chain acrylate or long-chain methacrylate include (meth) acrylates having an aliphatic amino group,
Nitrogen-containing heterocyclic vinyl monomers, N-vinyl-substituted cyclic amide monomers, (meth) acrylamides, aromatic-substituted ethylene monomers having a nitrogen-containing group, nitrogen-containing vinyl ether monomers, etc. And hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, Examples thereof include copolymers with monomers such as lauryl (meth) acrylate, stearyl (meth) acrylate, vinyl laurate, vinyl stearate, benzyl (meth) acrylate, and phenyl (meth) acrylate.

The charge control agents exemplified above can be used alone or in combination of two or more. The charge control agent has an appropriate value depending on the desired chargeability, but may be added to the carrier liquid in a range of about 0.01% to 100% by weight of the toner. A dispersant (dispersion stabilizer) may be added to the carrier liquid in order to stabilize the dispersion of the toner particles in the liquid developer. As the dispersant (dispersion stabilizer), a polymer or the like which is adsorbed on the toner particles and which has an affinity for the carrier liquid and is soluble, semi-soluble or swellable in the carrier liquid can be used.

Examples of the polymer having solubility, semi-solubility or swelling in a carrier liquid include, but are not limited to, polyolefin-based petroleum resins, linseed oil, polyalkyl methacrylate and the like. In order to increase the value, a copolymer of a monomer having a polar group such as methacrylic acid, acrylic acid, and alkylaminoethyl methacrylate can also be used. In this case, the solubility in the carrier liquid, the affinity to the toner particles, and the adsorptivity can be controlled by the amount of the polar group to be copolymerized. Affinity and adsorptivity increase.

The dispersant is preferably added in an amount of about 0.01% by weight to 20% by weight based on the carrier liquid from the viewpoint of improving dispersibility and preventing the viscosity of the carrier liquid from increasing due to its addition. More preferably 0.1% by weight or more
It is about 10% by weight. The ratio (solid content ratio) of the total weight of the solid components such as the toner, the charge control agent, and the dispersant to the total weight of the liquid developer is preferably about 1% by weight to 90% by weight. In order to reduce the total amount of the liquid developer used for development and facilitate handling, the solid content ratio is more preferably 2%.
% By weight to about 50% by weight.

[0039]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In the following examples, “parts” means “parts by weight” unless otherwise specified, and “Tg” means “glass transition temperature”. Further, “Mw” indicates a weight average molecular weight, and “Mn” indicates a number average molecular weight.

In the following examples, the acid value was determined according to JIS
It was measured under the conditions of the K5400 method. The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined from the results of gel permeation chromatography (GPC). GPC is a high-performance liquid chromatography pump TRI
ROTAR-V type (manufactured by JASCO Corporation), UV spectroscopy detector
UVIDEC-100-V type (manufactured by JASCO Corporation), 50c
m length column Shodex GPC A-803
(Manufactured by Showa Denko KK). Weight average molecular weight (M
w) was determined as the weight average molecular weight in terms of polystyrene (Mw) by calculating the molecular weight of the test sample from the results of the chromatography using polystyrene as a standard substance. Also, the number average molecular weight (Mn) was determined in the same manner from the result of the chromatography. The test sample used was one in which 0.05 g of a binder resin was dissolved in 20 ml of tetrahydrofuran (THF).

The glass transition temperature (Tg) was measured using a differential scanning calorimeter DSC-20 (manufactured by Seiko Instruments Inc.) under the conditions of a sample amount of 10 mg and a heating rate of 10 ° C./min. Α-alumina powder was used as a standard substance. The temperature of the sample was once raised to a temperature higher than the Tg, then lowered, and then raised again to a temperature higher than the Tg.
After maintaining the temperature for a minute, the value at the second RUN was measured.

The volume average particle size is measured by a laser diffraction type particle size distribution analyzer SALD-1100 (manufactured by Shimadzu Corporation).
It measured using. Production of binder resin (thermoplastic saturated polyester resin) Polyester resin 1 A propylene oxide adduct of bisphenol A was placed in a round bottom flask equipped with a reflux condenser, a water / alcohol separator, a nitrogen gas inlet tube, a thermometer and a stirring device. 1750
Parts and 790 parts of isophthalic acid, nitrogen gas was introduced with stirring, and dehydration polycondensation was performed at a temperature of 200 ° C to 240 ° C. When the acid value of the produced polyester resin or the viscosity of the reaction solution reaches a predetermined value, the temperature of the reaction system is raised to 1
The temperature was lowered to 00 ° C. or lower to stop the polycondensation. The obtained polyester resin 1 had Mw = 8500, Mn = 3750,
Tg = 58.1 ° C., acid value = 9.5 mg KOH / g. Polyester resin 2 In the same manner as in the production of polyester resin 1, dehydration polycondensation of propylene oxide adduct of bisphenol A and isophthalic acid was performed, and the acid value of the produced polyester resin or the viscosity of the reaction solution became a predetermined value. The polycondensation was stopped to obtain a polyester resin 2. Polyester resin 2 has Mw = 6500, Mn = 3050, Tg = 5
2.3 ° C., acid value = 11.0 mg KOH / g. Polyester Resin 3 In the production of the polyester resin 1, 1700 parts of bisphenol A propylene oxide adduct and 890 parts of isophthalic acid were reacted, and the reaction was performed when the acid value of the produced polyester resin or the viscosity of the reaction solution reached a predetermined value. The temperature of the system was lowered to 100 ° C. or lower to stop the polycondensation. The obtained polyester resin 3 had Mw = 5050, M
n = 2550, Tg = 50.9 ° C., acid value = 45.2 mg
KOH / g. Polyester Resin 4 In the production of the polyester resin 1, instead of reacting the propylene oxide adduct of bisphenol A with isophthalic acid, 1250 parts of bisphenol A ethylene oxide adduct was reacted with 1090 parts of isophthalic acid to produce When the acid value of the polyester resin or the viscosity of the reaction solution reaches a predetermined value, the temperature of the reaction system is raised to 1
The temperature was lowered to 00 ° C. or lower to stop the polycondensation. The obtained polyester resin 4 had Mw = 5900, Mn = 2350, T
g = 48.1 ° C., acid value = 75.0 mgKOH / g. Polyester resin 5 In a round-bottomed flask equipped with a reflux condenser, a water / alcohol separator, a nitrogen gas inlet tube, a thermometer and a stirrer, 1250 parts of ethylene oxide adduct of bisphenol A and 1090 parts of isophthalic acid were added. Nitrogen gas was introduced with stirring, and dehydration polycondensation was performed at a temperature of 200 ° C to 240 ° C. At an appropriate time, the temperature of the reaction system was lowered to 100 ° C. or lower while monitoring the acid value of the produced polyester resin or the viscosity of the reaction solution, and the polycondensation was temporarily stopped. Next, 70 parts of trimellitic acid were added, and the reaction temperature was increased to 2 again.
The reaction is continued by increasing the temperature to 00 ° C. to 240 ° C., and when the acid value of the produced polyester resin or the viscosity of the reaction solution reaches a predetermined value, the temperature of the reaction system is reduced to 100 ° C. or less,
The polycondensation was stopped. The obtained polyester resin 5 has M
w = 5050, Mn = 2150, Tg = 45.1 ° C., acid value = 95.0 mgKOH / g. Polyester resin 6 In a round bottom flask equipped with a reflux condenser, a water / alcohol separator, a nitrogen gas inlet tube, a thermometer, and a stirrer, 1250 parts of ethylene oxide adduct of bisphenol A and 1090 parts of isophthalic acid were added. Nitrogen gas was introduced with stirring, and dehydration polycondensation was performed at a temperature of 200 ° C to 240 ° C. At an appropriate time, the temperature of the reaction system was lowered to 100 ° C. or lower while monitoring the acid value of the produced polyester resin or the viscosity of the reaction solution, and the polycondensation was temporarily stopped. Next, 100 parts of trimellitic acid is added, the reaction temperature is raised again to 200 ° C. to 240 ° C., and the reaction is continued. When the acid value of the produced polyester resin or the viscosity of the reaction solution reaches a predetermined value, the reaction is performed. The temperature of the system was lowered to 100 ° C. or less, and the polycondensation was stopped. The obtained polyester resin 6
Is Mw = 4950, Mn = 2130, Tg = 42.1
° C, acid value = 105.0 mgKOH / g. Examples of liquid developer production Example 1 60 parts of the polyester resin 2 and Tone as a colorant
r Yellow HG VP2155 (Clariant, PY180)
Was mixed with a kneader equipped with three rolls to obtain 18 parts of the mixture.
The mixture was kneaded at 0 ° C. for 4 hours to obtain a high-concentration colorant kneaded product. This high-concentration colorant kneaded material was diluted with the polyester resin using a kneader to finally obtain a colored resin kneaded material having a PY180 concentration of 15% by weight. After sufficiently cooling the colored resin kneaded material, coarsely pulverized using a cutter mill, and further finely pulverized using a jet mill (manufactured by Nippon Pneumatic Industries, Ltd.) to obtain a colored toner coarse particle having an average particle size of about 10 μm. I got 30 g of this colored toner coarse particle is 0.25% by weight.
Petroleum Barium Sulfonate Sulfol Ba-30N
IP Solvent 1620 (manufactured by Matsumura Oil Research Institute Co., Ltd.)
The solution was mixed with 70 g, and sand grinder (IGA
RASHI KIKAI SEIZO CO. , Lt
d. 1 mm diameter glass beads (150 cc)
Wet grinding was performed in a / 8 gallon vessel at a cooling water temperature of 20 ° C. and a disk rotation speed of 2000 rpm for 10 hours. Thus, a concentrated liquid developer having a volume average toner particle diameter of 2.5 μm was obtained.

Further, in 100 parts of the concentrated liquid developer,
900 parts of a 0.25% by weight sulfol Ba-30N IP Solvent 1620 solution was added to dilute the dispersion, and the dispersion was treated with T.I. K. The liquid developer 1 was manufactured by performing a dispersion treatment at 8000 rpm for 5 minutes using an auto homomixer type M (manufactured by Tokushu Kika Kogyo Co., Ltd.). Examples 2, 3, 4 In the same manner as in Example 1, except that polyester resins 3, 4, and 5 were used in place of polyester resin 2, respectively, the volume average toner particle diameter was 2.5 μm.
Of liquid developers 2, 3, and 4. Comparative Examples 1 and 2 Comparative liquid developers having a volume average toner particle diameter of 2.5 μm in the same manner as in Example 1 except that polyester resins 1 and 6 were used instead of polyester resin 2 in Example 1, respectively. 1 and 2 were obtained.

Next, the evaluation of the chargeability of the toner for the liquid developers 1 to 4 and the comparative liquid developers 1 and 2 will be described. Chargeability is in standard condition (15 ° C / 25RH)
%) And the zeta potential of the liquid developer in a high temperature and high humidity state (35 ° C./85 RH%). The zeta potential indicates the potential of the electrostatic double layer on the particle surface in a system in which particles having surface charges are dispersed in a liquid, and is a value related to the chargeability of the toner in a liquid developer. The higher the zeta potential, the higher the migration speed of the toner in the carrier liquid, and the desired development can be performed even in a high-speed system.

The zeta potential was measured using a zeta potential measuring instrument LAZ.
ER ZEE MODEL 501 and PEN KEM
501 non-aqueous measurement system (PEN KE
(Manufactured by M Corporation), the toner particles were electrophoresed by applying a voltage, and the toner particles were observed by laser irradiation. The sample used was diluted 100-fold with a 0.5 wt% sulfol Ba-30N IP solvent 1620 solution.

When the absolute value of the zeta potential is 70 mV or more, and the difference between the zeta potential in a standard state and the zeta potential in a high temperature and high humidity state is within 5 mV, a stable and good image is not affected by the environment. Characteristics are obtained. This case was determined to be good (良好). The absolute value of the zeta potential is 70 m.
When the value was less than V, or the difference between the zeta potential under the standard condition and the zeta potential under the high temperature and high humidity condition was greater than 5 mV, it was judged as defective (x). The results are shown in the following table.

Acid value Zeta potential (mV) Comprehensive evaluation (mgKOH / g) Standard condition High temperature and high humidity condition Difference Example 1 11.0 71 72 1 ○ Example 2 45.2 95 97 2 ○ Example 3 75.0 120 122 2 ○ Example 4 95.0 150 154 4 ○ Comparative Example 1 9.5 68 680 × Comparative Example 2 105.0 168 175 7 × According to this, the acid value of the binder resin is 10 mgKOH.
Examples 1 to 4 of the present invention having a concentration of 100 mgKOH / g to 100 mgKOH / g
It can be seen that, in the liquid developers 1 to 4, the toner exhibited high chargeability, and exhibited good chargeability which was not so different from the standard state even under high temperature and high humidity conditions. On the other hand, in the comparative liquid developer 1 of Comparative Example 1 in which the acid value of the binder resin was less than 10 mgKOH / g, the zeta potential in the standard state was too low. In the comparative liquid developer 2 of Comparative Example 2 in which the oxidation of the binder resin exceeded 100 mgKOH / g, the zeta potential was sufficiently high, but the difference between the zeta potential in the standard state and the zeta potential in the high temperature and high humidity state was too large. .

As a result, the liquid developer of the present invention has a sufficiently high zeta potential and stable chargeability irrespective of environmental temperature and humidity. This shows that high-speed development can be performed. Note that, here, the embodiment regarding the liquid developer is described. However, even when the same toner including a colorant and a binder resin as in each embodiment is used as a dry toner, the toner for forming an image is the same. It is considered that stable and good toner chargeability can be obtained in the same manner as in each of the above embodiments.

[0049]

According to the present invention, there are provided a yellow electrophotographic toner and a yellow electrophotographic liquid developer capable of forming a full-color image, which are safe for the environment and the like, and have sufficient chargeability. The present invention can provide an electrophotographic toner and an electrophotographic liquid developer capable of performing high-speed development.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuaki Yome 2-3-13 Azuchicho, Chuo-ku, Osaka City International Building Minolta Co., Ltd. F-term (reference) 2H005 AA01 AA21 CA08 CA21 EA10 2H069 BA01 CA06 CA27 DA00

Claims (2)

[Claims] An electrophotographic toner comprising a colorant and a binder resin as main components, wherein the colorant is Color.
The binder resin contains a compound classified as Index Pigment Yellow 180 and / or a derivative thereof, and the binder resin has an acid value of 10 mgKOH / g to 100 mgK.
An OH / g toner for electrophotography. 2. An electrophotographic liquid developer in which the electrophotographic toner according to claim 1 is dispersed in an electrically insulating carrier liquid.