Color Toner For Developing Electrostatic Latent Image

Abstract
The color toner for developing electrostatic latent images comprising a colored resin particle containing at least a binder resin, a colorant, a charge control agent and a parting agent, wherein an extracted liquid with water by means of a hot water extraction method from said colorant has a pH value in the range from 6.0 to 8.0, said colored resin particle has a volume average particle diameter (Dv) in the range from 4 to 10 μm and an average circularity in the range from 0.93 to 0.995, an amount of extracted components with methanol is 7% by weight or less, and an amount of residual volatile compounds is 500 ppm or less. The color toner for developing electrostatic latent images has excellent image-reproducibility and environmental durability and can form an image with a stable image density under a high temperature and high humidity condition.
Description
EXAMPLE

The present invention is hereinafter to be described more specifically by the following examples. Such examples, however, are not to be construed as limiting in any way the scope of the present invention. All designations of “part” or “parts” and “%” used in the following examples mean part or parts by weight and wt. % unless expressly noted.


(1) Volume Average Particle Diameter and Particle Diameter Distribution

A volume average particle diameter (Dv) and a particle diameter distribution, i.e., a ratio (Dv/Dp) of the volume average particle diameter to a number average particle diameter (Dp), of the toner was measured by means of a particle diameter measuring device (“MULTISIZER”, trade name, manufactured by Beckman Coulter, Inc.). The measurement by the Multisizer was conducted under the following conditions:


Aperture diameter: 100 μm;


Medium: Isothone II;


Concentration: 10% and


Number of particles measured: 100,000 particles.


(2) Average Circularity

100 μl of an aqueous solution of 0.1% sodium dodecyl sulfonate (an anionic surfactant) as a dispersion medium was added to 20 mg of a color toner for developing electrostatic latent images and blended. And, 10 ml of ion-exchanged water was added to the toner solution and stirred, and then the toner solution was dispersed using an ultrasonic dispersion apparatus of 60 W for 30 minutes. A toner concentration at a measurement was adjusted to 3,000 to 10,000/μl, and then 1,000 to 10,000 of the toner particle having a circle equivalent diameter of 1 μm or more were evaluated using a flow particle image analyser “FPIA-2100” (trade name), manufactured by Sysmex Corporation. From the measurement, an average circularity was obtained.


(3) A pH Value and Electrical Conductivity of an Extracted Liquid with Hot Water from Colorant

Colorant weighed 5 g was charged in a 300 ml beaker, and 10 ml of ethanol and 10 ml of water were charged in the beaker and blended with the colorant. And, 180 ml if ion-exchanged water having an electric conductivity of 1 μS/cm and a pH value of 7.0 was added to the colorant solution. Then, the colorant solution was sufficiently stirred and then boiled for 5 minutes to extract water-soluble component from the colorant thereby to obtain an extracted liquid. After cooling the obtained extracted liquid down to room temperature (about 25° C.), the extracted water was charged in a 200 ml measuring flask. And then, another ion-exchanged water, which had been boiled and then cooled down to room temperature (about 25° C.), was added to the measuring flask such that a total amount of the extracted water and the ion-exchanged water was 200 ml. After stirring the solution sufficiently, the solution was filtrated with a filter paper (No. 5C, Filter paper, manufactured by Toyo Roshi Kaisha, Ltd.). And, the filtrate was measured for a pH value using a pH meter (“D-14”, trade name, manufactured by Horiba Ltd.) and for an electrical conductivity using a conductivity meter (“ES-12”, trade name, manufactured by Horiba Ltd.).


(4) Amount of Extracted Liquid with Methanol

The color toner for developing electrostatic latent images weighed about 0.8 to 1.0 g was put in a cylindrical filter paper (No. 86R, manufactured by Toyo Roshi Kaisha, Ltd.) previously weighed, and the cylindrical filter paper was set on a Soxhlet extractor. Then, an extraction was performed for 6 hours using 100 ml of methanol as a solvent. The cylindrical filter paper, in which the color toner after the extraction was put, was vacuum-dried at 50° C. for 1 hour. Then, a ratio (%) of a weight, which was subtracted the weight of the dry cylindrical filter paper from a total weight of the previously weighed cylindrical filter paper and the previously weighed color toner, to the weight of the previously weighed color toner was set to an amount (%) of an extracted component with methanol.


(5) Amount of Insoluble Component in Tetrahydrofuran

A color toner for developing electrostatic latent images weighed about 1 g was charged into a Soxhlet extractor equipped with a cylindrical filter (No. 86R, 29×100 mm, manufactured by Toyo Roshi Kaisha, Ltd.) and was refluxed with about 100 ml of tetrahydrofuran (THF) as a solvent for 5 hours. The reflux was carried out at a rate in which one droplet of the solvent was dropped every 5 to 15 minutes. After completion of the reflux, the cylindrical filter was air-dried in a draft for one night and further dried under reduced pressure at 50° C. for 1 hour, and then weighed. Then, an amount of insoluble component in tetrahydrofran was measured using the following expression.

  • An amount of insoluble component in tetrahydrofran (% by weight)=(S/T)×100.


In the expression, T represents an amount (g) of the color toner for developing electrostatic latent images and S represents an amount (g) of the insoluble component remaining on the filter paper after the reflux.


(6) Amount of Residual Volatile Compound

An amount of residual volatile compounds was obtained using a purge&trap/gas chromatography method (a P&T/GC method) described below.


0.1 g of a color toner for developing electrostatic latent images was charged into a purge container and heated at a heating rate of 10° C./minute from room temperature while passing helium gas as a carrier gas in the container at a flow rate of 50 ml/minutes, and then maintained at 200° C. for 30 minutes. And, a volatilized compound generated by the heating was caught in to a trap tube at −130° C. Then, the caught volatilized compound was determined to obtain an amount of residual volatile compounds.


As the measurement apparatus, a gas chromatograph 6890 (trade name, FID method, manufactured by Agilent Technologies Japan, Ltd.), C-R7A chromatopack (trade name, manufactured by Shimadzu Corporation), a purge&trap sampler of TDC (trade name, manufactured by Agilent Technologies Japan, Ltd.) and a column of DB-5 (trade name, manufactured by J&W, L=30 m, I.D=0.32 mm, Film=0.25 μn) were employed.


Measurement Conditions


A temperature of the column: 50° C. (maintained for 2 minutes) to 270° C. (a heating rate of 10° C./minutes),


A sample transfer temperature: 280° C.,


A detection temperature: 280° C.,


A carrier gas: helium gas,


A flow rate: 1 ml/minutes.


(7) Polymerization Stability

An aqueous dispersion containing colored resin particle after a polymerization reaction dispersed therein was passed to a mesh (20 mesh), and aggregate remaining on the mesh was dried and measured for the weight. The measured weight was set to a weight of the aggregate. Polymerization stability was obtained by an amount of aggregate, which was calculated using the following expression, as an index (note that a total amount of solid after the polymerization in the following expression did not include an amount of dispersion stabilizer). The smaller the amount of aggregate was, the better the polymerization stability was.

  • An amount of aggregate (%)=(the weight (g) of the aggregate/the total amount of solid after the polymerization)×100.


(8) Minimum Fixing Temperature

A fixing test was conducted using a commercially available non-magnetic-one-component developing type printer (printing speed: 18 sheet/min machine) modified such that the temperature of its fixing roll portion would be variable. The fixing test was performed by varying the temperature of the fixing roll of the modified printer by 5° C. at a time, and measuring the fixing rate of the developer at each temperature to determine a relationship between a temperature and a fixing rate. The fixing rate was calculated from a ratio of an image density after a tape peeling treatment to that before the treatment in a black solid printing area in a test sheet printed by the modified printer. That is, the fixing rate was calculated from the following equation:





Fixing rate (%)=(IDAfter/IDBefore)×100


where IDBefore represents the image density before tape peeling treatment, and IDAfter represents the image density after tape peeling treatment.


The tape peeling treatment means a series of steps consisting: applying an adhesive tape (Scotch Mending Tape 810-3-18, trade name, manufactured by Sumitomo 3M Limited) to a portion of the test sheet to be evaluated, pressing the adhesive tape at a constant pressure, and then peeling the adhesive tape at a constant speed in a direction along the sheet. The image density was measured by use of a Macbeth's reflection type image density measuring device. The toner fixing temperature denotes the temperature of the fixing roll at which the fixing rate became 80% or more in the fixing test. A toner having a lower fixing temperature is superior because the toner has a low-temperature fixability and thus can be used in a high-printing speed model printer.


(9) Image Density

Copy papers were set in a commercially available non-magnetic-one-component developing type printer (printing speed: 18 sheet/min machine), and the color toner for developing electrostatic latent images was put in a developing device of the printer and was left standing over one day and one night under an (N/N) environment at a temperature of 23° C. and a humidity of 50%. Then, printing was continuously performed at an image density of 5%. And, a solid image was printed every 10 papers printing. Then, an image density of the printed solid image was measured using a Macbeth's reflective image density measuring apparatus. In the same manner, after leaving the color toner for developing electrostatic latent images under a condition of a temperature of 50° C. and a humidity of 80% for 2 weeks, the color toner was put in the developing device under an (N/N) condition and an image density was measured.


(10) Environmental Durability

The printer used in (9) was left standing under each condition of an (N/N) condition of a temperature of 23° C. and a humidity of 50% and a (H/H) condition of a temperature of 35° C. and a humidity of 80% for one day and one night. Printing was continuously performed at an image density of 5%. And, at every 500 papers printing, a solid pattern and a plain pattern were printed.


A printed solid pattern image was measured for an image density in the same way as (9).


And, after the plain pattern printing, the color toner developed a non-image on the photoconductive member after developing was adhered to an adhesive tape (Scotch Mending Tape 810-3-18, trade name, manufactured by Sumitomo 3M Limited). Then, the adhesive tape was stuck on a new sheet of paper to measure a color tone (B) using a spectroscopic color-difference meter (“SE2000”, trade name, manufactured by Nippon Denshoku Industries Co., Ltd.). In the same way, an unused adhesive tape was stuck on the same new sheet of paper to measure a color tone (A). Then, the color tones were shown on a L*a*b* space coordinates, and a color difference ΔE* was calculated by the two color tones to obtain a fog value. As the fog value is small, fog generated on a printed image is small.


Environmental durability was evaluated by checking a number of the continuously printed paper capable of keeping an image quality of an image density of 1.3 or more and an fog value of 1% or less. Final number of the paper was set to 10,000. The samples having 10,000 or more in a table show that the aforesaid image quality is kept even after 10,000 papers printing.


Example 1

83 parts of styrene, 17 parts of N-butylacrylate, 6 parts of C.I. Pigment Yellow 74 (“Fast Yellow 7415”, trade name, manufactured by SANYO COLOR WORKS, LTD.), 0.8 parts of divinylbenzene and 0.25 parts of polymethacrylate ester macromonomer (“AA6”, trade name, manufactured by Toagosei CO., LTD.) were mixed and dispersed using a media type dispersion apparatus (“PICO MILL”, trade name, manufactured by ASADA IRON WORKS. CO., LTD.) to prepare a dispersion of colorant. To the prepared dispersion of colorant, 2 parts of positive charge control resin (styrene.n-butylacrylate.N,N-diethyl-N-methyl-2-(methacryloyloxy) ethyl aluminum p-toluenesulfonic acid copolymer, a weight average molecular weight:18,000, a glass transition temperature: 60° C., an amount of functional group: 2%, manufactured by FUJIKURA KASEI CO., LTD.), 0.8 parts of 2,2,4,6,6-pentamethylheptane-4-thiol and 10 parts of dipentaerythritol hexamyristate (a hydroxy value: 1.5 mgKOH/g) were dispersed at room temperature using a bead mil to prepare a polymerizable monomer composition for core.


Separately, an aqueous solution containing 5.5 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water was gradually added to an aqueous solution containing 9.8 parts of magnesium chloride dissolved in 250 parts of ion-exchanged water, with stirring, to prepare a colloidal dispersion of magnesium hydroxide.


And, 1 parts of methyl methacrylate and 65 parts of water were mixed to prepare an aqueous dispersion of polymerizable monomer for shell.


The polymerizable monomer compound for core obtained above was added to the colloidal dispersion of magnesium hydroxide obtained above, and the mixture was stirred until droplets stabilized. After the droplets stabilized, 3 parts of dimethyl 2,2′-azobis (2-methylpropionate) (“V601”, trade name, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the mixture, and then the mixture was stirred at 15,000 rpm under shearing force using an Ebara Milder (“MDN303V”, trade name, manufactured by Ebara Corporation) for 30 minutes to form smaller fine droplets of the polymerizable monomer composition for core.


The colloidal dispersion of magnesium hydroxide in which the droplets of the polymerizable monomer composition for core were dispersed was charged into a reactor equipped with an agitating blade, and heated to 85° C. to initiate a polymerization reaction. At the time when the conversion of the monomer into a polymer reached almost 100%, the aqueous dispersion of the polymerizable monomer for shell and 0.3 parts of 2,2′-azobis-(2-methyl-N(2-hydroxyethyl)propionamide) (“VA-086”, trade name, manufactured by Wako Pure Chemical Industries, Ltd.), as a water-soluble polymerization initiator, dissolved in 20 parts of ion-exchanged water were charged into the reactor. After the polymerization reaction was continued for 4 hours, the polymerization reaction was stopped and the dispersion was cooled to obtain an aqueous dispersion of colored resin particles.


Then, while maintaining the temperature at 85° C., nitrogen gas was injected into the reactor through a pipe mounted at the lower part of the reactor to replace vapor phase existing in the upper of the reactor with the nitrogen gas. And, under stirring with the agitating blade, nitrogen gas was injected into the reactor at a rate of 0.08 m3/hr·Kg to be subjected to a stripping treatment for 10 hours for removing residual volatile compounds. Then, the aqueous dispersion of core-shell type colored resin particle was cooled at room temperature.


While stirring the aqueous dispersion of colored resin particles thus prepared at a room temperature, the pH of the system was adjusted to 5 or lower using sulfuric acid to be subjected to acid washing (25° C., 10 minutes). After the aqueous dispersion was filtered to separate water, 500 parts of ion-exchanged water was newly added thereto to form a slurry again to subject to water washing. Thereafter, the dehydration and water washing were repeatedly performed several times at room temperature, and solids was separated by filtration from the solution and dried at 40° C. for two days and two nights using a dryer to prepare dried colored resin particles. The colored resin particles thus obtained had a volume average particle diameter (Dv) of 9.1 μm, a particle diameter distribution (Dv/Dp) of 1.23 and an average circularity of 0.973.


To 100 parts of the colored resin particles obtained above, 1 part of silica having a degree of hydrophobic property of 65% and a volume average particle diameter of 12 nm and 1 part of silica having a volume average particle diameter of 40 nm were added and mixed for 10 minutes at 1,400 rpm using HENSCHEL MIXER to prepare color toner for developing electrostatic latent images. Property of the color toner and image quality of a printed image developed using the color toner were evaluated according to the above-mentioned manner. The results were shown in table 1.


Example 2

In same way as the preparation of Example 1, except that C.I. Pigment Yellow 74 was exchanged for 6 parts of a solid dispersion pigment (manufactured by Fuji Pigment Co., Ltd.) of C.I. Pigment Red 150 and C.I. Pigment Red 31, color toner for developing electrostatic latent images was obtained. Property of the color toner for developing electrostatic latent images and image quality of a printed image developed using the color toner were evaluated as with Example 1. The results were shown in table 1.


Example 3

In the same way as the preparation of Example 1, except that C.I. Pigment Yellow 74 was exchanged for 6 parts of cyan colorant produced such that C.I. Pigment Blue 15:3 (“BX121”, trade name, manufactured by Dainippon Ink And Chemicals, Incorporated) was dispersed into a hot water, boiled for 20 minutes and rewashed, color toner for developing electrostatic latent images was obtained. Property of the color toner for developing electrostatic latent images and image quality of a printed image developed using the color toner were evaluated as with Example 1. The results were shown in table 1.


Comparative Example 1

To 100 parts of positive charge control resin (a weight average molecular weight: 12000, a glass transition temperature: 67° C.) produced by mixing 83 parts of styrene, 15 parts of N-butylacrylate and 2 parts of N-diethyl-N-methyl-2-(methacryloyloxy) ethyl ammonium P-toluenesulfonic acid, 24 parts of toluene and 6 parts of methyl ethyl ketone were dispersed, and then the mixture was stirred by rolls under cooling. After the positive charge control resin was winded on the roll, 100 parts of C.I. Pigment Yellow 74 (“SEIKAFAST YELLOW 2017E”, trade name, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) and 40 parts of hydrophobicitizing-treated silica particles (“RX-50”, trade name, manufactured by Nippon Aerosil co., ltd.) having a primary particle diameter of 40 nm were gradually added and kneaded for 40 minutes to prepare a positive charge control resin composition. During this period, the clearance between the rolls was initially 1 mm, broadened gradually, to finally to 3 mm, and an organic solvent (a solvent mixture of methyl ethyl ketone/methanol=4/1) was added occationally according to mixing and kneading condition of the charge control resin composition. After the mixing, the used organic solvent was removed under reduced pressure.


Separately, an aqueous solution containing 6.9 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water was gradually added to an aqueous solution containing 9.8 parts of magnesium chloride dissolved in 250 parts of ion-exchanged water, with stirring, to prepare a colloidal dispersion of magnesium hydroxide.


A monovinyl monomer comprising 90 parts of styrene and 10 parts of n-butyl acrylate, 14.4 parts of the obtained positive charge control compound, 3 parts of t-dodecyl mercaptan and 10 parts of pentaerythritol tetrastearate were stirred and mixed to be dispersed uniformly to prepare a polymerizable monomer composition for core.


And, 2 parts of methyl methacrylate and 100 parts of water were mixed to prepare an aqueous dispersion of polymerizable monomer for shell.


The polymerizable monomer composition for core obtained above was added to the colloidal dispersion of magnesium hydroxide obtained above, and the mixture was stirred until droplets stabilized. After the droplets stabilized, 6 parts of t-butylperoxy-2-ethylhexanoate (“PERBUTYL O”, trade name, manufactured by NOF CORPORATION) was added to the mixture, and then the mixture was stirred at 15,000 rpm under shearing force using an Ebara Milder (“MDN303V”, trade name, manufactured by Ebara Corporation) for 30 minutes to form smaller fine droplets of the polymerizable monomer mixture for core.


The colloidal dispersion of magnesium hydroxide in which the droplets of the polymerizable monomer composition for core were dispersed was charged into a reactor equipped with an agitating blade, and then heated. At the time when the conversion of the monomer into a polymer reached almost 100%, the aqueous dispersion of the polymerizable monomer for shell and 0.2 parts of 2,2′-azobis-(2-methyl-N-(2-hydroxyethyl)-propionamide) (“VA-086”, trade name, manufactured by Wako Pure Chemical Industries, Ltd.,), as a soluble initiator, dissolved in 65 parts of ion-exchanged water were charged into the reactor. After the polymerization reaction was further continued for 8 hours, the reaction was stopped to obtain an aqueous dispersion of core-shell type colored resin particles having a pH value of 9.5.


While stirring the aqueous dispersion of colored resin particles thus prepared, the pH of the system was adjusted to 5 using sulfuric acid to be subjected to acid washing (25° C., 10 minutes). After the aqueous dispersion was filtered to separate water, 500 parts of ion-exchanged water was newly added thereto to form a slurry again to subject to water washing. Thereafter, the dehydration and water washing were repeatedly performed several times at a room temperature, and solids was separated by filtration from the solution and dried at 45° C. for two days and two nights using a dryer to prepare dried colored resin particles. The colored resin particles thus obtained had a volume average particle diameter (Dv) of 9.1 μm, a particle diameter distribution (Dv/Dp) of 1.23 and an average circularity of 0.973.


To 100 parts of the colored resin particles obtained above, 1 part of silica having a degree of hydrophobic property of 65% and a volume average particle diameter of 12 nm and 2 parts of silica having a volume average particle diameter of 40 nm were added and mixed for 10 minutes at 1,400 rpm using HENSCHEL MIXER to prepare color toner for developing electrostatic latent images. Property of the color toner for developing electrostatic latent images and image quality of a printed image developed using the color toner were evaluated as with Example 1. The results were shown in table 2.


Comparative Production Example 2

In the same way as the preparation of Comparative Production Example 1 except that C.I. Pigment Yellow 74 was exchanged for C.I. Pigment Red 57:1 (“carmine 6B”, trade name, manufactured by SANYO COLOR WORKS, LTD.), color toner for developing electrostatic latent images was obtained. Property of the color toner for developing electrostatic latent images and image quality of a printed image developed using the color toner were evaluated as with Example 1. The results were shown in table 2.


Comparative Example 3

In the same way as the preparation of Comparative Production Example 1 except that C.I. Pigment Yellow 74 was exchanged for C.I. Pigment Blue 15:3 (“B-120”, trade name, manufactured by SANYO COLOR WORKS, LTD.), color toner for developing electrostatic latent images was obtained. Property of the color toner for developing electrostatic images and image quality of a printed image developed using the color toner were evaluated as with Example 1. The results were shown in table 2.













TABLE 1







Ex. 1
Ex. 2
Ex. 3



















<Property of Colored Resin Particle>





Volume average particle diameter
9.1
9.3
9.2


(μm)


Particle diameter distribution
1.23
1.22
1.26


(Dv/Dp)


Average circularity
0.973
0.978
0.967


Amount of extracted component with
3.3
3.6
3.1


methanol (wt %)


Amount of insoluble component in
65
61
60


THF (ppm)


Amount of residual volatile
90
110
120


compound (ppm)


<Colorant>


pH of extracted liquid with hot water
7.0
7.3
7.0


Conductivity of extracted liquid with
98
77
17


hot water (μ s/cm)


Polymerization stability
0.2
0.1
0.1


<Evaluation of Printed Image>


Minimum fixing temperature (° C.)
140
140
140


Image Density


Starting
1.42
1.40
1.38


After 2 weeks
1.27
1.30
1.27


Environmental Durability


N/N
10,000
10,000
10,000



or more
or more
or more


H/H
10,000
10,000
10,000



or more
or more
or more
















TABLE 2







Table 1











Com. Ex.
Com. Ex.
Com. Ex.



1
2
3














<Property of Colored Resin Particle>





Volume averageparticle diameter
9.1
9.5
9.3


(μm)


Particle diameter distribution
1.20
1.24
1.21


(Dv/Dp)


Average circularity
0.973
0.965
0.962


Amount of extracted component with
6.8
6.4
6.2


methanol (wt %)


Amount of insoluble component in
68
71
70


THF (ppm)


Amount of residual volatile
300
450
380


compound (ppm)


<Colorant>


pH of extracted liquid with hot water
8.9
8.4
5.8


Conductivity of extracted liquid with
40
24
38


hot water (μ s/cm)


Polymerization stability
8.0
10.1
5.2


<Evaluation of Printed Image>


Minimum fixing temperature (° C.)
150
150
145


Image Density


Starting
1.32
1.40
1.18


After 2 weeks
0.95
1.15
1.00


Environmental Durability


N/N
8,500
8,500
9,000


H/H
5,000
5,500
6,000









The results of the evaluation of the toners for developing electrostatic latent images shown in the tables 1 and 2 show the following facts.


The color toners for developing electrostatic latent images of the Comparative Example 1 to 3, in which a pH value of extracted liquid with water by means of a hot water extraction method from the colorant and an amount of extracted liquid with methanol were outside of the scope of the present invention, form an image with a low image density especially when the toners are left under a condition of a temperature of 50° C. and a humidity of 80%, showing insufficient environmental durability.


On the contrary, the color toners for developing electrostatic latent images of the Examples 1 to 3 according to the present invention form an image with a high image density, showing good environmental durability.

Claims
  • 1. A color toner for developing electrostatic latent images comprising a colored resin particle containing at least a binder resin, a colorant, a charge control agent and a parting agent, wherein an extracted liquid with water by means of a hot water extraction method from said colorant has a pH value in the range from 6.0 to 8.0,said colored resin particle has a volume average particle diameter (Dv) in the range from 4 to 10 μm and an average circularity in the range from 0.93 to 0.995,an amount of extracted components with methanol is 7% by weight or less, andan amount of residual volatile compounds is 500 ppm or less.
  • 2. The color toner for developing electrostatic latent images according to claim 1, wherein an amount of insoluble component in tetrahydrofran is in the range from 30 to 95% by weight.
  • 3. The color toner for developing electrostatic latent images according to claim 1, wherein the colorant is C.I. Pigment Yelloww 74.
  • 4. The color toner for developing electrostatic latent images according to claim 3, wherein an electrical conductivity of an extracted liquid with water by means of a hot water extraction method from the colorant is in the range from 10 to 130 μS/cm.
  • 5. The color toner for developing electrostatic latent images according to claim 1, wherein the colorant is a mixture of C.I. Pigment Red 31 and C.I. Pigment Red 150.
  • 6. The color toner for developing electrostatic latent images according to claim 5, wherein an electrical conductivity of an extracted liquid with water by means of a hot water extraction method from the colorant is in the range from 10 to 100 μS/cm.
  • 7. The color toner for developing electrostatic latent images according to claim 1, wherein the colorant is C.I. Pigment Blue 15:3 or C.I. Pigment Blue 15:4.
  • 8. The color toner for developing electrostatic latent images according to claim 7, wherein an electrical conductivity of an extracted liquid with water by means of a hot water extraction method from the colorant is in the range from 10 to 40 μS/cm.
  • 9. The color toner for developing electrostatic latent images according to claim 1, wherein a pH value of an extracted liquid with water by means of a hot water extraction method from the colorant is in the range from 6.5 to 8.0.
  • 10. The color toner for developing electrostatic latent images according to claim 1, wherein the parting agent is a multifunctional ester compound.
  • 11. The color toner for developing electrostatic latent images according to claim 1, wherein a product (axb) of “a” showing a hydroxy value (mgKOH/g) of the parting agent and “b” showing an addition amount of the parting agent per 100 parts by weight of the binder resin is in the range from 0.5 to 40.
  • 12. The color toner for developing electrostatic latent images according to claim 1, wherein the charge control agent comprises a charge control resin.
  • 13. The color toner for developing electrostatic latent images according to claim 1, wherein the colored resin particle is produced by a polymerization reaction.
Priority Claims (1)
Number Date Country Kind
JP2004-085076 Mar 2004 JP national
PCT Information
Filing Document Filing Date Country Kind 371c Date
PCT/JP05/04453 3/14/2005 WO 00 6/18/2007