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Title:
TONER PARTICLES AND ELECTROPHOTOGRAPHIC IMAGE FORMING DEVICE COMPRISING THE SAME
Document Type and Number:
WIPO Patent Application WO/2009/072823
Kind Code:
A2
Abstract:
Provided is toner particles comprising a binder resin and a colorant, wherein the binder resin includes a polyester resin having a weight average molecular weight of about 6,000 to about 100,000, a glass transition temperature of about 55 to about 70oC, and polydispersity index (Mw/Mn) of about 3 to about 25, and the toner particles have a volume average diameter of about 2 to about 10 µm and a 80% span value of 0.9 or less. Unlike conventional toner that has a poor fixing property, the toner particles have a small volume average diameter, a narrow particle size distribution, improved fixing property, and improved high temperature storage stability even though the polyester resin is used as the binder resin.

Inventors:
YANG WOO YOUNG (KR)
KIM KEON IL (KR)
HWANG DAE IL (KR)
KIM IL HYUK (KR)
PARK JAE BUM (KR)
HWANG IL SUN (KR)
HWANG JAE KWANG (KR)
CHOI DAE WOONG (KR)
KIM DONG WON (KR)
AHN DUCK KYUN (KR)
Application Number:
PCT/KR2008/007171
Publication Date:
June 11, 2009
Filing Date:
December 04, 2008
Export Citation:
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Assignee:
SAMSUNG FINE CHEMICALS CO LTD (KR)
YANG WOO YOUNG (KR)
KIM KEON IL (KR)
HWANG DAE IL (KR)
KIM IL HYUK (KR)
PARK JAE BUM (KR)
HWANG IL SUN (KR)
HWANG JAE KWANG (KR)
CHOI DAE WOONG (KR)
KIM DONG WON (KR)
AHN DUCK KYUN (KR)
International Classes:
G03G9/08
Foreign References:
KR20070103613A
KR20070012889A
KR20060114341A
Attorney, Agent or Firm:
Y.P. LEE, MOCK & PARTNERS (Seocho-dong Seocho-gu, Seoul 137-875, KR)
Download PDF:
Claims:
Claims

[1] Toner particles comprising a binder resin and a colorant, wherein the binder resin comprises a polyester resin having a weight average molecular weight of about 6,000 to about 100,000, a glass transition temperature of about 55 to about 70 0 C, and polydispersity index Mw/Mn of about 3 to about 25, and the toner particles have a volume average diameter of about 2 to about 10 μm and an 80% span value of about 0.9 or less.

[2] The toner particles of claim 1, wherein the polyester resin comprises a content of insolubles in tetrahydrofuran (THF) in an amount of about 0.1 to about 20 weight%.

[3] The toner particles of claim 1, having a circularity in a range of about 0.92 to about 0.99.

[4] The toner particles of claim 1, wherein the polyester resin comprises a water dis- persible functional group, and has an acid value of about 4 to about 20 mgKOH/ g- [5] The toner particles of claim 4, wherein the water dispersible functional group comprises a metal salt of at least one selected from the functional group consisting of a hydroxyl group, a mercapto group, a carboxylic acid group, a phosphoric acid group, a sulfonic acid group, and a sulfuric acid group.

[6] The toner particles of claim 4, wherein the water dispersible functional group is sodium sulfonate group and, in the polyester resin, the content of dicarboxylic acid residue that comprises sodium sulfonate group is about 0.05 to about 0.5 mol% based on the total amount of dicarboxylic acid residue.

[7] The toner particles of claim 1, wherein the colorant comprises at least one pigment selected from the group consisting of a cyan pigment, a magenta pigment, a yellow pigment, a black pigment, and a white pigment.

[8] The toner particles of claim 1, further comprising at least one selected from the group consisting of a releasing agent, a charge control agent, and an external additive.

[9] The toner particles of claim 8, wherein the releasing agent comprises at least one selected from the group consisting of ester wax, carnauba wax, polyethylene wax, polypropylene wax, beeswax, paraffin wax, and a mixture of these materials.

[10] The toner particles of claim 8, wherein the charge control agent comprises at least one selected from the group consisting of a positive charge control agent, a negative charge control agent, and a mixture of the positive and negative charge control agents.

[11] The toner particles of claim 8, comprising the colorant in an amount of about 2 to about 15 weight%, the releasing agent in an amount of about 0.1 to about 30 weight%, the charge control agent in an amount of about 0.1 to about 8 weight%, and the polyester resin as a remaining portion. [12] An electrostatic latent image developing agent comprising: the toner particles of any one of claims 1 through 11 ; and a carrier. [13] The electrostatic latent image developing agent of claim 12, wherein the carrier comprises at least one selected from the group consisting of ferrite coated with an insulating material, magnetite coated with an insulating material, and iron powder coated with an insulating material. [14] A method of forming an electrophotographic image using the toner particles of any one of claims 1 through 11. [15] A method of forming an electrophotographic image using the electrostatic latent image developing agent of claim 12. [16] An electrophotographic image forming device using the toner particles of any one of claims 1 through 11. [17] An electrophotographic image forming device using the electrostatic latent image developing agent of claim 12.

Description:

Description TONER PARTICLES AND ELECTROPHOTOGRAPHIC IMAGE

FORMING DEVICE COMPRISING THE SAME

Technical Field

[1] This application claims the benefit of Korean Patent Application No.

10-2007-0125761, filed on December 5, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. The present invention relates to toner particles and an electrophotographic image forming device comprising the toner particles, and more particularly, to toner particles which may simultaneously attain particle characteristics suitable for high speed printing and physical properties such as fixing property, high temperature storage stability, etc., and an electrophotographic image forming device comprising the toner particles. Background Art

[2] In the printing industry, the demand for a toner that is suitable for high speed printing, in particular, a toner having enhanced fixing properties and high temperature storage stability while having a small volume average diameter and a narrow size distribution, is increasing.

[3] In general, a toner is manufactured by adding a colorant, a charge control agent and/ or a releasing agent to a thermoplastic resin that acts as a binder resin. Also, in order to increase fluidity of the toner or to improve properties such as charge controlling or cleaning properties of the toner, an inorganic material such as silica, titanium oxide, and/or a metal powder may be added to the toner as external additives.

[4] The thermoplastic resin that acts as a binder resin may be polyester resin or vinyl resin.

[5] Vinyl resin provides toner particles having a uniform diameter since the vinyl resin is manufactured using a chemical method such as suspension polymerization or emulsion polymerization. However, since the chemical method accompanies a radical polymerization, it is difficult to achieve complete polymerization, and as a result, unreacted monomers or surfactants may remain in the toner particles. Thus, the charge characteristics of the toner particles are reduced due to the unreacted monomers remaining in the toner particles.

[6] Polyester resin is suitable for using in a high speed printing toner since the polyester resin has a low melt viscosity and can be readily melted. However, in conventional toner particles, even though a polyester resin is used as the binder resin, the conventional toner particles can not meet the physical properties required for high speed printing.

[7] For example, toner particles that are manufactured using a pulverization method, which is a conventional method of manufacturing a toner, in which a polyester resin is used as the binder resin, have a drawback in that particle size of the toner particles is not uniform. Japanese Patent Publication No. 3326703 discloses toner particles that are manufactured by a method comprising: mixing a dispersion of a polyester resin and a releasing agent emulsion to form a mixture; and agglomerating the mixture. However, the toner particles have unsatisfactory fixing property.

[8] In this way, a toner that is manufactured using a conventional polyester resin has drawbacks in that the toner particle size is not uniform or fixing property is not satisfactory despite the intrinsic advantages of the resin.

[9] Therefore, there is a need to develop a toner that addresses the technical problems in the prior art, has a small volume average diameter, a narrow size distribution, an improved fixing characteristic, and improved high temperature storage stability, and which is suitable for high speed printing while using polyester resin. Disclosure of Invention Technical Problem

[10] The present invention provides toner particles having a small volume average diameter, a narrow size distribution, a superior fixing property, and high temperature storage stability.

[11] The present invention also provides an electrostatic latent image developing agent that includes the toner particles.

[12] The present invention also provides a method of forming an electrophotographic image using the toner particles or the electrostatic latent image developing agent.

[13] The present invention also provides an electrophotographic image forming device that includes the toner particles or an electrostatic latent image developing agent. Technical Solution

[14] According to an aspect of the present invention, there is provided a toner particle including a binder resin and a colorant, wherein the binder resin includes a polyester resin having a weight average molecular weight of about 6,000 to about 100,000, a glass transition temperature of about 55 to about 70 0 C, and polydispersity index Mw/ Mn of about 3 to about 25, and the toner particles have a volume average diameter of about 2 to about 10 μm and a 80% span value of about 0.9 or less.

[15] According to an aspect of the present invention, there is provided an electrostatic latent image developing agent including toner particles and a carrier.

[16] According to an aspect of the present invention, there is provided a method of forming an electrophotographic image using the toner particles or the electrostatic latent image developing agent.

[17] According to an aspect of the present invention, there is provided an electrophotographic image forming device including the toner particles or the electrostatic latent image developing agent. Advantageous Effects

[18] Present invention provides toner particles which may simultaneously attain particle characteristics suitable for high speed printing and physical properties such as fixing property, high temperature storage stability, etc., and an electrophotographic image forming device comprising the toner particles. Best Mode

[19] The present invention will now be described more fully with reference to exemplary embodiments of the invention.

[20] Toner particles according to an embodiment of the present invention include a binder resin and a colorant. The binder resin includes a polyester resin having a weight- average molecular weight of about 6,000 to about 100,000, a g lass transition temperature of about 55 to about 70 0 C, and a polydispersity index Mw/Mn of about 3 to about 25. The toner particles have a volume average diameter of about 2 to about 10 μm and 80% span value of about 0.9 or less.

[21] If the volume average diameter of the toner particles exceeds 10 μm, the size of the toner particles becomes unsuitable for high speed printing due to its increased size. Also, if the 80% span value exceeds 0.9, the non-uniformity of the toner particles is increased, and thus, an incomplete charging of the particle or contamination of the device may occur. In order to prevent these problems, a classifying process should be performed to remove toner particles having a diameter greater than a predetermined size. The 80% span value is about 0.9 or less, and is not specifically limited to, but may be about 0.1 to about 0.9.

[22] The polyester resin included in the toner particles may have a content of insolubles about 0.1 to about 20 weight% with respect to a tetrahydrofuran (THF) solvent, preferably, 0.3 to 10 weight%, and more preferably 0.5 to 5 weight%. If the content of insolubles with respect to the THF solvent exceeds 20 weight %, the viscosity of the solution is highly increased because of the presence of the content of insolubles, and if the content of insolubles is less than 0.1 weight%, the high temperature fixing property of the toner particles is deteriorated.

[23] The toner particles may have a circularity of about 0.92 to about 0.99. If the circularity of the toner particles exceeds 0.99, the toner particles may remain on a photosensitive drum in a cleaning step, and thus, can cause a malfunction of the device, and if the circularity of the toner particles is less than about 0.92, the transfer rate can be reduced, and thus, the rate of toner consumption can be increased.

[24] The polyester resin included in the toner particles includes a water dispersible functional group, and may have an acid value of about 4 to about 20 mgKOH/g. In the above acid value range, the toner particles can acquire a rapid charging rate and a large amount of charge.

[25] The water dispersible functional group may include a metal salt of at least one selected from the group consisting of a hydroxyl group, a mercapto group, a carboxylic acid group, a phosphoric acid group, a sulfonic acid group, and a sulfuric acid group. More specifically, the water dispersible functional group may be a sodium sulfonate group. For the polyester resin, the content of dicarboxylic acid residue that includes a sodium sulfonate group may be about 0.05 to about 0.5 mol% based on the total amount of the dicarboxylic acid residue. If the content of dicarboxylic acid residue that includes sodium sulfonate group is within the above range, the water dispersibility of the polyester resin can be readily realized, and thus, the reduction of charge amount due to moisture absorption of the toner particles can be prevented even if the toner particles are stored in a high temperature and high humidity environment. Also, since the polyester resin includes the water dispersible functional group, the dispersibility of the polyester resin with respect to a polarized solvent may be increased.

[26] The colorant, such as a cyan pigment, a magenta pigment, a yellow pigment, a black pigment, a white pigment, or a mixture of these materials, included in the toner particles may be appropriately selected in consideration of hue, chroma, brightness, weather resistance, transparency, or the affinity to a binder resin.

[27] Examples of the colorant are as follows. The black pigment may be SB4, SB7, SB9, titanium oxide, or carbon black. The cyan pigment may be a copper phthalocyanine compound or derivatives thereof, anthraquin compound, or a basic dye late compound. More specifically, the cyan pigment may be C.I. pigment blue 1,7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, or 66. The magenta pigment may be a fused nitrogen compound, an anthraquin compound, a quinacridone compound, a basic dye late compound, a napthol compound, a benzoimidazol compound, a thioindigo compound, or a perylene compound. More specifically, the magenta pigment may be C.I. dye red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, or 254. The yellow pigment may be a fused nitrogen compound, a isoindolinone compound, an anthraquin compound, an azo metal complex compound, or an allylimide compound. More specifically, the yellow pigment may be C.I. dye yellow 12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, or 168. These pigments may be selected in consideration of color coordinate and/or color density.

[28] If the content of the colorant is greater than 15 weight% , the elasticity of the toner particles is increased, and as a result, it is difficult to form fine particles or the particle size distribution can be broadened. On the other hand, if the content of the colorant less

than 2 weight%, the coloring of the toner particles is reduced, and thus, the impression of color of an image is insufficient when printing. Therefore, the content of the colorant may be about 2 to about 15 weight%, and preferably, 4 to 12 weight % based on the total weight of the toner particles.

[29] The colorant can be used as it is, but also may be used in a colorant masterbatch type in which the colorant is dispersed in a resin composition. In this way, when the colorant is used in a masterbatch type, the surface exposure of the colorant is repressed, and thus, the charging capability of the toner particles can be increased.

[30] The colorant masterbatch means a resin composition in which a high concentration of colorant is uniformly dispersed, and is manufactured by a method comprising a colorant and a resin are kneaded at a high temperature and high pressure, or by a method comprising: dissolving a resin in a solvent and a colorant is added to the formed solution; and dispersing colorant by applying a high shear force. In the latter case, the solvent must be completely removed before using the toner. In the masterbatch, a pigment is uniformly dispersed compared to a simple mixing. However, one thing to note is that, although the masterbatch is pulverized to a very small size when the masterbatch is dispersed in a medium, the resin used for the masterbatch does not completely dissolved in the solvent. That is, even though the particle size of the masterbatch is reduced, the masterbatch can maintain a structure in which a surface of the colorant particle is surrounded by the resin.

[31] In general, when a large amount of polarized groups, which are present in the colorant, appear on a surface of toner particles, the polarized groups function to discharge charges accumulated in the toner, and as a result, the charging rate and the amount of the charge on the toner are reduced. However, in the case of the toner that uses a colorant masterbatch, a high concentration of pigment is uniformly dispersed in the polyester resin, and thus, direct exposure of the pigment on the surface of the toner particles can be prevented. That is, the pigment particles are encapsulated, which is very advantageous for controlling the charge of the toner.

[32] In the current embodiment, the content of the pigment in the colorant masterbatch may be about 10 to about 60 weight%, and preferably, 20 to 40 weight%.

[33] The toner particles may additionally include an additive, such as a releasing agent, a charge control agent, and/or an external additive.

[34] The releasing agent is an additive that can increase the fixing property of a toner image, and may be ester wax, carnauba wax, polyethylene wax, polypropylene wax, bees wax, paraffin wax, or a mixture of these materials. If the content of the releasing agent is less than 0.1 weight%, it is difficult to fix the toner particles without using oil, and if the content of the releasing agent is greater than 10 weight%, the toner may agglomerate when the toner is stored for a long period of time.

[35] Therefore, the content of the releasing agent included in the toner particle according to the current embodiment may be 0.1 to 30 weight%, and preferably, 1 to 10 weight% based on the total weight of the toner particle.

[36] The charge control agent may be appropriately selected according to the charge of a final toner, and may be a positive charge control agent, a negative charge control agent, or a mixture of the positive and negative charge control agents.

[37] The positive charge control agent may be largely classified into an azine-type and a quaternary ammonium salt according to the chemical structure thereof. Azine-type positive charge control agents are mainly black in color, and thus, can be used for manufacturing black-colored toner, and quaternary ammonium salt is in a white powder state, and accordingly, can be used for manufacturing toner of any color. The negative charge control agent may be largely classified into a white color charge control agent of tert-butyl salicylic acid metal salt group and a black color charge control agent of azo group. In the tert-butyl salicylic acid metal salt group, a central metal may be chrome, aluminium, zinc, calcium, boron, or acetylboron, and, in the case of the azo group, a central metal may be chrome or iron. When the metal salt is added to the toner particles, the charging rate and/or amount of charge can be controlled.

[38] The content of the charge control agent included in the toner particles according to the current embodiment may be about 0.1 to about 8 weight%, and preferably, 0.3 to 5 weight% based on the total weight of the toner particles. If the content of the charge control agent is less than 0.1 weight %, the charging rate of the toner is reduced and the amount of charge is reduced, and if the content of the charge control agent is greater than 8 weight%, too many charges are distributed on the surface of the toner, and thus, image distortion may occur.

[39] The toner particles according to the current embodiment may include the colorant in an amount of about 2 to about 15 weight%, the releasing agent in an amount of about 0.1 to about 30 weight%, the charge control agent in an amount of about 0.1 to about 8 weight%, and the polyester resin as a remaining portion.

[40] The toner particles may also include higher fatty acid, fatty acid amide, or their metal salts. The higher fatty acid, fatty acid amide, or their metal salts prevents the degradation of various developing characteristics, and thus, can be appropriately used to obtain high quality images.

[41] Besides the above additives, an external additive, such as a fluidizing agent, having very small organic or inorganic particles may be added and coated on the surface of the toner particles according to the current embodiment. The external additive increases the fluidity of the particles to be used as toner or controls charge characteristics such as amount of charge and charging rate. For example, the external additive may be finely classified hydrophobic silica particles; hydrophilic silica particles; silica particles

having their surfaces coated with a conductive material such as strontium or calcium; silica particles having their surfaces coated with indium tin oxide or antimony tin oxide, which is a semiconductor; titanium oxide particles having their surfaces coated with a conductive material such as a titanium oxide, strontium, or calcium; titanium oxide particles having their surfaces coated with indium tin oxide or antimony tin oxide, which is a semiconductor; zinc stearate particles; magnesium stearate particles; alumina particles; polymethylmetacrylate particles; polystyrene particles; or silicon particles.

[42] The toner particles according to the current embodiment can be manufactured in various non- spherical shapes according to the types of surfactant, polarized solvent, organic solvent, auxiliary solvent, and/or viscosity increasing agent even though the same physical shear force is applied to the toner particles, and also, toner particles having various shapes can be manufactured by changing the temperature for removing the organic solvent.

[43] The toner particles according to the current embodiment can be manufactured in various ways. That is, the method is not specifically limited as long as the toner particles having the above properties can be manufactured using a method that is used in the art.

[44] The toner particles according to the current embodiment can be manufactured using, for example, the following method. First, a solution containing a polarized medium, an organic solvent, and a surfactant is added to a reactor and then stirred therein at room temperature, thereby forming a solvent emulsion, which is a state in which the organic solvent is dispersed in the polar medium. Next, toner components such as a resin, a colorant, a releasing agent (wax), and a charge control agent are added to the solvent emulsion so that the toner components can be dissolved into the organic solvent. Next, the solvent emulsion that includes the toner components is heated to remove the organic solvent and fine particles of toner are recovered.

[45] A practical detailed description of the method of manufacturing a toner described above is disclosed in the Korean patent application No. 10-2007- 0096804, and thus, the full description of 10-2007- 0096804 is incorporated herein.

[46] According to another embodiment of the present invention, there is provided an electrostatic latent image developing agent that includes toner particles and a magnetic carrier (solid carrier particles). The magnetic carrier may be coated with an insulating material. More specifically, the magnetic carrier is a carrier generally used in a two- component developing method, and may be ferrite coated with an insulating material, magnetite coated with an insulating material, iron powder coated with an insulating material, or a mixture of these materials. The magnetic carrier may be the ferrite coated with an insulating material or the magnetite coated with an insulating material.

[47] According to another embodiment of the present invention, there is provided a method of forming an electrophotographic image using the toner particles and the electrostatic latent image developing agent.

[48] The method according to the present embodiment includes attaching toner particles or an electrostatic latent developing agent on a surface of a photosensitive body on which an electrostatic latent image is formed to form a toner image, and transferring the toner image onto a transferring medium, wherein the toner particles and the electrostatic latent developing agent is the toner particles and electrostatic latent developing agent according to an embodiment of the present invention as described above.

[49] A practical detailed description of the method of forming an electrophotographic image is disclosed in Korean Patent Publication No. 2007-0013945, and thus the full description of Korean Patent Publication No. 2007-0013945 is incorporated herein.

[50] According to another embodiment of the present invention, there is provided an electrophotographic image forming device that employs the toner particles or the electrostatic latent image developing agent. Here, the electrophotographic image forming device may be a laser printer, a copier, or a facsimile.

[51] According to the current embodiment, provided is an electrophotographic image forming device that includes a photosensitive body, a means for charging a surface of the photosensitive body, a means for forming an electrostatic latent image on the surface of the photosensitive body, a means for receiving a toner or a developing agent, and a means for forming a toner image by supplying the toner or the developing agent and developing the electrostatic latent image of the surface of the photosensitive body, wherein the toner or the developing agent is the toner or the developing agent according to an embodiment of the present invention. Mode for Invention

[52] The present invention will now be described in detail with reference to the following examples. However, these examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[53] Terminologies, properties of obtained resins, or properties of obtained toner particles are defined or measured using the following methods if not specifically defined.

[54] Measurement of volume average diameter

[55] The volume average diameter was measured using a Coulter LS particle size analyzer

( Coulter Electronics Co., Ltd., Saint Petersburg). In the Coulter multisizer, the aperture size was 100 μm, an appropriate amount of surfactant was added to 50 to 100ml of ISOTON-II( Beckman Coulter Co.) electrolyte, and 10 to 15 mg of measuring sample was added to the electrolyte, and afterwards, the resultant mixture was dispersed by an ultrasonic homogenizer for one minute, thereby forming a sample.

[56] The volume average diameter L is a terminology defined on Page 3 in the Powder

Technology Handbook (K. Gotoh et al., 2nd Edition, Marcell Dekker Publications, 1997).

[57] Measuring 80% span value

[58] The 80% span value is an index that specifies a size distribution of particles. A diameter corresponding to 10% based on volume, that is, if the volume of the particles are accumulated by measuring the particle sizes from the smallest to the largest, a diameter corresponding to 10% of the total volume is defined as d 10, a diameter corresponding to 50% of the total volume is defined as d50, and a diameter corresponding to 90% of the total volume is defined as d90. The dlO, d50, and d90 values are obtained from a particle size distribution chart, and the obtained values are substituted in Equation 1.

[59] [Equation 1]

[60] 80% span value= (d90-dl0)/d50

[61] where, the smaller the 80% span value, the narrower the particle size distribution, and vice versa.

[62] Circularity measurement

[63] The circularity was measured using a FPIA-3000 (a product of Sysmex Co., Japan).

In order to measure the circularity using the FPIA-3000, a sample was manufactured such that an appropriate amount of a surfactant was added to 50 to 100 ml of distilled water, and then, 10 to 20 mg of toner particles was added to the distilled water. Afterwards, the mixture was dispersed by an ultrasonic homogenizer for one minute .

[64] The circularity was automatically obtained in the FPIA-3000 using Equation 2.

[65] [Equation 2]

[66] Circularity =

2-Jarea x π perimeter

[67] In Equation 2, the area indicates an area where the toner is projected, and the perimeter means the circumference of a circle that has the same area as the area where the toner is projected. The circularity can have a value of 0 to 1, with a circularity of 1 indicating a perfect sphere.

[68] Glass transition temperature (Tg, 0 C) measurement

[69] The glass transition temperature was measured using a differential scanning calorimeter (a product of Netzs Co.). After raising the temperature of a sample from 20 to 200 0 C by heating at a heating rate of 10° C /min., the sample was quenched to 10 0 C at a cooling rate of 20°C/min., and then heated at a heating rate of 10° C /min.

[70] Acid value measurement

[71] The acid value (mgKOH/g) was measured such that, after dissolving a resin in di- chloromethane and cooling it, the solution was titrated using a 0.1 N KOH methyl alcohol solution.

[72] Molecular weight measurement

[73] Molecular weight was measured using a Gel Permeation Chromatography (Waters

Alliance GPC 2000 systems). The solvent used was tetrahydrofuran (THF), and the molecular weight was measured by making a calibration line of molecular weight using as a polystyrene standard.

[74] THF insoluble content measurement

[75] The insoluble content of the resin in THF was measured such that, after dissolving a resin in THF, the content of resin remaining in a gel state and not completely dissolved was measured.

[76] Preparation Example 1: Synthesis of Polyester Resin (1)

[77] A 3L reactor equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet, was installed in an oil bath. 0.5 mol of dimethylterephthalate, 0.495 mol of di- methylisophthalate, 0.005 mol of dimethyl 5-sulfoisophthalate sodium salt, 2.3 mol of 1,2-propylene glycol, and 0.02 mol of trimellitic acid were added to the 3L reactor. Next, 500 ppm of tetrabutyltitanate, which is a polymerization catalyst, with respect to the total weight of the monomer was added to the 3L reactor. Next, the temperature of the resultant product was increased to 150 0 C while the stirring speed of the 3L reactor was maintained at 100 rpm. The reaction was maintained for five hours. When methanol, which was a by-product from the esterification reaction, was not further produced in the condenser, the reaction temperature was increased to 220 0 C and the pressure of the 3L reactor was reduced to 0.1 torr, and the reaction was completed by maintaining the reaction for 15 hours.

[78] In the polyester resin manufactured as described above, on a basis of the dicarboxylic acid residue, the content of dicarboxylic acid residue that includes sodium sulfonate negative ion groups was 0.3 mol% with respect to the total dicarboxylic acid residue.

[79] Preparation Example 2: Synthesis of Polyester Resin (2)

[80] Polyester resin (2) was manufactured using the same method used to manufacture polyester resin (1) in Preparation Example 1 except for adding 0.98 mol of dimethyl- isophthalate, 0.02 mol of trimellitic acid, and 2.1 mol of butylene glycol as monomers for manufacturing polyester resin (2) instead of the monomers added in Preparation Example 1.

[81] Preparation Example 3: Preparation of Cyan Pigment Masterbatch (1)

[82] After mixing the polyester resin (1) synthesized in Preparation Example 1 and a blue pigment (CI. pigment blue 15:3, Color index (CI) No. 74160, a product of Japanese Ink Co. (DIC)) in a ratio of 6:4 on a weight basis, ethylacetate was added to the above

mixture in an amount of 50 parts by weight based on 100 parts by weight of the polyester resin (1), the temperature of the mixture was increased to approximately 60° C, and then the mixture was kneaded using a kneader. Next, while the mixture was mixed at a speed of 50 rpm using a biaxial extruder to which a vacuum pump was connected, ethylacetate as a solvent was removed using the vacuum pump, thereby obtaining a cyan pigment masterbatch (1).

[83] Example (1): Preparation of Cyan Toner

[84] 400 g of distilled water, 10 g of polyvinyl alcohol (P-24: a product of DC Chemical

Co. Seoul, Korea), 7 g of nonionic surfactant (tween 20: Aldrich Chemical Company, Milwaukee, Wisconsin, U.S.A.), and 4.2 g of anionic surfactant (Sodiumdodecylsulfate: Junsei Chemical Company, Tokyo, Japan) were added to a pressurizable 1 L reactor that was equipped with a condenser, a thermometer, and an impeller type stirrer com. The solid parts were completely dissolved by stirring the mixture at a speed of 500 rpm and a temperature of 70 0 C. 100 g of methyl ethyl ketone (Aldrich Chemical Company, Milwaukee, Wisconsin, U.S.A.) was mixed to the aqueous solution, and thus, a milk-white solvent emulsion was obtained.

[85] Next, 5 g of carnauba wax (SX-70: Max Chemical, Daejeon, Korea), 85 g of polyester resin (1) synthesized in Preparation Example 1, 15 g of cyan pigment masterbatch (1) manufactured in Preparation Example 3, and 2 g of charge control agent (N-23: HB Dinglong Co., Hubei, China) were sequentially added to the 1 L reactor. In this regard, the polyester resin (1) was pulverized to a size of approximately 1 mm.

[86] After preparing a mixture by stirring the above components at a speed of 1000 rpm, the mixture was heated to 72 0 C and stirred for 3 hours while refluxing, thereby producing an emulsion. After stirring, it was confirmed that the polyester resin (1) present on a bottom of the 1 L reactor was completely dissolved, and thus, a stable emulsion was obtained.

[87] Next, the methyl ethyl ketone, which is an organic solvent, was removed by reducing the stining speed to 300 rpm and heating the 1 L reactor to 90 0 C under partially reduced pressure of 100 mmHg.

[88] After 4 hours, when it was confirmed that all the methyl ethyl ketone was removed from the emulsion by measuring the amount of removed methyl ethyl ketone, the emulsion was cooled to 25°C.

[89] Next, toner particles were separated from the emulsion using a conventional filtering device. A filter cake was re-dispersed in distilled water and then, re-filtered the distilled water 4 times to completely remove the surfactant and viscosity increasing agent included in the filter cake.

[90] Dried toner particles were obtained by drying the re-filtered toner particles for one day in an oven maintained at a temperature of 40 0 C. Analysis of the obtained toner

particles showed that the toner particle s comprises 87.9 weight% of polyester resin, 5.6 weight% of colorant, 4.6 weight% of carnauba wax, and 1.9 weight% of charge control agent.

[91] Example 2: Preparation of Cyan Toner

[92] 85 g of polyester resin (1) manufactured in Preparation Example 1, 15 g of cyan pigment masterbatch (1) manufactured in Preparation Example 3, 2 g of charge control agent (N-23: HB Dinglong Co., Hubei, China), 5 g of carnauba wax (SX-70: Max Chemical, Daejeon, Korea), 300 g of methyl ethyl ketone (Aldrich Chemical Company, Milwaukee, Wisconsin, U.S.A.) were sequentially added to a pressurizable 1 L reactor that was equipped with a condenser, a thermometer, and an impeller type stirrer. While stirring the mixture at a speed of 600 rpm, 50 ml of NaOH aqueous solution was added to the mixture, and the mixture was mixed for 5 hours at a temperature of 80 0 C with reflux. After confirming that the mixture had a sufficient fluidity, the mixture was additionally mixed for 2 hours at a speed of 500 rpm.

[93] Meanwhile, 800 g distilled water, 10 g non-ionic surfactant (tween 20: a product of

Aldrich Chemical Company, Milwaukee, Wisconsin, U.S.A.), and 2g anionic surfactant (Sodiumdodecylsulfate: a product of Aldrich Chemical Company, Milwaukee, Wisconsin, U.S.A.) were added to a pressurizable 3 L reactor that was equipped with a condenser, a thermometer, and an impeller type stirrer, and the mixture was mixed for I hour at a speed of 600 rpm and at a temperature of 85°C. The toner component mixture prepared in the IL reactor was added to the above mixture and an emulsion was produced by stirring the mixture for 1 hour at a speed of 1000 rpm and at the same temperature. Next, the methyl ethyl ketone, which is an organic solvent, was removed by heating the 3 L reactor to a temperature of 90 0 C under a partially reduced pressure of 100 mmHg.

[94] After 4 hours, it was confirmed that all the methyl ethyl ketone was removed from the emulsion by measuring the amount of removed methyl ethyl ketone. The volume average diameter of the toner particles included in the emulsion from which methyl ethyl ketone was completely removed was measured as 0.4 μm.

[95] Next, the temperature of the 3 L reactor was reduced to 45°C, 10 g of MgCl 2 was dissolved in 50 g distilled water and the solution was slowly added to the 3 L reactor, the temperature of the mixture was increased to 80 0 C over 30 minutes, and 5 hours later, the volume average diameter of the particles included in the emulsion was measured. As a result, the volume average diameter was 6.2 μm.

[96] Next, 500 g of distilled water was added to the 3 L reactor and the resultant product was fused for 8 hours at a temperature of 80 0 C, and was cooled. Next, the toner particles were separated from the emulsion using a conventional filter device. Afterwards, a filter cake was washed with 1 N aqueous hydrochloric solution and then,

re-dispersed in distilled water and re-filtered the distilled water 4 times to completely remove the surfactant included in the filter cake. The re-filtered toner particles were dried in a vacuum oven for 5 hours at a temperature of 40 0 C, and thus, dried toner particles were obtained.

[97] Comparative Example 1 : Preparation of Cyan Toner [98] Toner particles were manufactured using the same method as in Example 1 except for using 85 g polyester resin (2) synthesized in Preparation Example 2 instead of 85 g polyester resin (1) synthesized in Preparation Example 1.

[99] The polyester resin and the toner particles manufactured in the preparation examples and the examples above were evaluated in the following manner.

[100] Evaluation of Property of Polyester Resin [101] The glass transition temperature Tg of the polyester resin manufactured in Preparation Examples 1 and 2, the insoluble content of the resin in THF, the acid value, the weight average molecular weight, and the polydispersity index (PDI) were measured using the method described above, and the measurement results are summarized in Table 1 below.

[102] [Table 1] [103] [Table 1] [Table ]

[104] As can be seen in Table 1, the polyester resin (2) manufactured in Preparation Example 2 has lower glass transition temperature Tg, PDI, and insoluble content of a resin in THF than those of the polyester resin (1) manufactured in Preparation Example 1.

[105] Measurement of Volume average diameter, 80% Span Value, and Circularity of toner particles [106] The volume average diameter, the 80% span value, and the circularity of the cyan toner particles manufactured in Examples 1 and 2 are summarized in Table 2 below. [107] [Table 2]

[108] [Table 2] [Table ]

[109] As can be seen in Table 2, the toner particles manufactured in Examples 1 and 2 according to the present invention have a volume average diameter of 10 μm or less, an 80% span value of 0.9 or less, and a circularity of 0.99 or less. However, the toner particles of Comparative Example 1 have properties beyond the above ranges shown in Table 2. Thus, it can be seen that the toner particles according to the embodiments of the present invention have a small volume average diameter and a narrow particle size distribution.

[HO] Evaluation of high temperature storage stability [111] 9.75 g of the toner particles manufactured in each of Examples 1 and 2 and Comparative Example 1, 0.2 g of silica (TG 810G: a product of Cabot Co,), and 0.05 g of silica (RX50: a product of Degussa Co.) were placed in a glass bottle and stored at a temperature of 50 0 C and 80% humidity for 72 hours. The high temperature storage stability was evaluated by observing with the naked eye. The evaluation results are summarized in Table 3 below . The symbols © , O, δ , and X in Table 3 are explained as follows.

[112] © : toner is not agglomerated; thus, no problem at all [113] O: slight agglomeration; however, when the toner is shaken, the agglomeration is released, and there is no practical difficulty for using

[114] δ : slight agglomeration; when the toner is shaken, the agglomeration is not readily released, and there is slight difficulty for using [115] X: strong agglomeration is present, the agglomeration is not easily released, and there is some practical difficulty for using

[116] Evaluation of fixing temperature range [117] Unfixed solid state images having a size of 30 mm x 40 mm were prepared by a Samsung CLP-510 printer using a toner manufactured by mixing 9.75 g of the toner particles manufactured in each of Examples 1 and 2 and Comparative Example 1, 0.2 g of silica (TG 810G: a product of Cabot Co,), and 0.05 g of silica (RX50: a product of Degussa Co.). Next, in a fixing tester which was modified so that a fixing temperature

could be arbitrarily changed, the fixing property of the unfixed images was evaluated by changing the fixing temperature of a fixing roller. The evaluation results are summarized in Table 3 below.

[118] [Table 3] [119] [Table 3] [Table ]

[120] The toner particles manufactured using the methods described in Examples 1 and 2 according to the present invention show improved fixing property and improved high temperature storage stability compared to the toner particles manufactured using the method described in Comparative Example 1.

[121] With regard to the fixing property, the upper limit of the fixing temperature range of Examples 1 and 2 is 200 to 210 0 C; however, that of Comparative Example 1 is 170 0 C, that is, the upper limit of the fixing temperature range of Examples 1 and 2 is increased compared to that of Comparative Example 1. Thus, the toner particles according to Examples 1 and 2 of the present invention may be fixed at a relatively wider temperature range compared to the toner particles of Comparative Example 1, and thus, the possibility that the fixing roller is contaminated by the toner particles at a high fixing temperature is low.

[122] With regard to the high temperature storage stability, the toner particles according to Examples 1 and 2 show improved high temperature storage stability compared to the toner particles of Comparative Example 1.

[123] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Industrial Applicability

[124] Present invention provides toner particles which may simultaneously attain particle characteristics suitable for high speed printing and physical properties such as fixing property, high temperature storage stability, etc., and an electrophotographic image forming device comprising the toner particles.