Electrostatic image developing toner

Abstract

Provided is an electrostatic image developing toner containing toner particles having a domain-matrix structure formed with a matrix of an amorphous polyester resin and a domain of a crystalline resin, wherein the toner particles contain an releasing agent and alkoxy aniline; and a content of the alkoxy aniline contained in the toner particles is in the range of 0.1 to 15.0 mass ppm.

Claims

1. An electrostatic image developing toner containing toner particles having a domain-matrix structure formed with a matrix of an amorphous polyester resin and a domain of a crystalline resin, wherein the toner particles contain an releasing agent and alkoxy aniline; and a content of the alkoxy aniline contained in the toner particles is in the range of 0.1 to 15.0 mass ppm.

2. The electrostatic image developing toner described in claim 1, wherein the releasing agent has a melting point in the range of 60 to 90 C.

3. The electrostatic image developing toner described in claim 1, wherein the toner particles contain C. I. Pigment Yellow 74 as a pigment.

4. The electrostatic image developing toner described in claim 3, wherein the toner particles contain at least one pigment selected from the group consisting of: C. I. Pigment Yellow 93, C. I. Pigment Yellow 155, C. I. Pigment Yellow 180, C. I. Pigment Yellow 185, C. I. Solvent Yellow 93, and C. I. Solvent Yellow 163.

5. The electrostatic image developing toner described in claim 1, wherein the crystalline resin in the toner particles is a crystalline polyester resin.

6. The electrostatic image developing toner described in claim 5, wherein a content of the crystalline polyester resin in the toner particles is in the range of 5 to 30 mass %.

7. The electrostatic image developing toner described in claim 5, wherein the crystalline polyester resin is a hybrid resin bonded with an amorphous resin segment.

8. The electrostatic image developing toner described in claim 5, wherein the crystalline polyester resin has an acid value in the range of 15 to 30 mg KOH/g.

9. The electrostatic image developing toner described in claim 1, wherein the alkoxy aniline is 2-methoxyaniline.

10. The electrostatic image developing toner described in claim 5, wherein the amorphous polyester resin has a high molecular weight component and a low molecular weight component; the high molecular weight component has a weight average molecular weight (Mw) in the range of 30,000 to 300,000; and the low molecular weight component has a weight average molecular weight (Mw) in the range of 8,000 to 25,000.

11. The electrostatic image developing toner described in claim 10, wherein the high molecular weight component in the amorphous polyester resin has an acid value smaller than the acid value of the crystalline polyester resin.

Description

EXAMPLES

(1) Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. In the present examples, the description of parts or % is used, it represents mass parts or mass % unless specific notice is given.

(2) <Synthesis of Crystalline Polyester Resin (C1)>

(3) Into a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, were added 281 mass parts of tetradecanedioic acid and 206 mass parts of 1,6-hexanediol. The temperature of the reaction mixture was raised to 190 C. over a period of 1 hour. After confirming that the reaction system was uniformly stirred, 0.003 mass % of Ti(OBu).sub.4 was added as a catalyst with respect to 100 mass % of tetradecanedioic acid, then, the temperature of the reaction mixture was raised from 190 C. to 240 C. over a period of 6 hours while removing the produced water. Further, with keeping the temperature at 240 C., the dehydration-condensation reaction was continued to perform polymerization. Thus it was obtained a crystalline polyester resin (c1).

(4) The obtained crystalline polyester resin (C1) had a number average molecular weight (Mn) of 4,400 and an acid value of 20 mg KOH/g. The acid value of the crystalline polyester resin was measured based on the method described in JIS K0070-1966. The acid values of the following crystalline polyester resins were measured in the same way.

(5) <Synthesis of Crystalline Polyester Resin (C2)>

(6) The crystalline polyester resin (C2) is a hybrid crystalline polyester resin, and it was synthesized as follows.

(7) TABLE-US-00001 (Preparation of crystalline polyester resin segment (CPEs)) Adipic acid 330 mass parts Ethylene glycol 45 mass parts 1,4-Butanediol 135 mass parts

(8) The above-described raw monomers for a crystalline polyester resin segment (CPEs) were introduced in a four-necked flask equipped with a nitrogen introducing tube, a dehydration tube, a stirrer, and a thermocouple. Then, the mixture was heated to 170 C. to dissolve the content. Then, Ti(OBu).sub.4 was added as an esterification catalyst (0.003 mass % with respect to the total amount of the polycarboxylic acid monomer). While keeping the temperature of the mixture at 170 C., the reaction was made for 5 hours with removing the produced water. Then, after the reaction was further made for 60 minutes, the unreacted monomers were removed under a reduced pressure (8 kPa).

(9) (Preparation of Amorphous Polyester Resin Segment (APEs))

(10) Into a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a temperature sensor, and a rectifying column were placed the following raw monomers for the amorphous polyester resin segment (APEs). The temperature of the reaction mixture was raised to 190 C. over a period of 1 hour. Then, it was confirmed that the reaction system was uniformly stirred. Afterward, Ti(OBu).sub.4 was added as an esterification catalyst (0.003 mass % with respect to the total amount of the polycarboxylic acid monomers). While keeping the temperature of the mixture at 190 C., the reaction was made for 5 hours with removing the produced water.

(11) TABLE-US-00002 (Preparation of hybrid crystalline polyester resin) (Polycarboxylic acid monomers) Terephthalic acid (TPA) 3.3 mass parts Fumaric acid (FA) 0.3 mass parts Trimellitic acid (TMA) 0.6 mass parts (Polyhydric alcohol monomers) 2,2-bis(4-phydroxyohenyl)propane-ethylene 2.1 mass parts oxide adduct (1:2) (BPA-EO) 2,2-bis(4-phydroxyohenyl)propane-propylene 6.9 mass parts oxide adduct (1:2) (BPA-PO)

(12) Into the reaction vessel in which the above-described crystalline polyester resin segment (CPEs) was prepared were added 0.8 mass parts of Ti(OBu).sub.4 as an esterification catalyst and the above-described amorphous polyester resin segment (APEs). The temperature of the mixture was raised to 235 C. The reaction was made under a normal pressure (101.3 kPa) for 5 hours, then further, the reaction was made under a reduced pressure (8 kPa) for 1 hour.

(13) Then, after cooling the mixture to 200 C., the reaction was made under a reduced pressure (20 kPa) for 1 hour. By this, it was obtained a crystalline polyester resin (C2) that was a hybrid crystalline polyester resin.

(14) The crystalline polyester resin (C2) had a number average molecular weight (Mn) of 7,500 and an acid value of 25 mg KOH/g.

(15) <Synthesis of Amorphous Polyester Resin (A1)>

(16) Into a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a temperature sensor, and a rectifying column were placed the following polycarboxylic acid monomers and polyhydric alcohol components. The temperature of the reaction mixture was raised to 190 C. over a period of 1 hour. Then, it was confirmed that the reaction system was uniformly stirred. Afterward, Ti(OBu).sub.4 was added as an esterification catalyst (0.004 mass % with respect to the total amount of the polycarboxylic acid monomers). The temperature of the reaction mixture was raised from 190 C. to 240 C. over a period of 6 hours with removing the produced water. The polymerization reaction was done by continuing the dehydration-condensation reaction at 240 C. for 10 hours. Then, the reaction mixture was subjected to a reduced pressure to obtain an amorphous polyester resin (A1). The obtained resin had a weight average molecular weight (Mw) of 68,000 and an acid value of 15 mg KOH/g. The acid value of the amorphous polyester resin was measured based on the method described in JIS K0070-1992. The acid values of the following amorphous polyester resins were measured in the same way.

(17) TABLE-US-00003 <Synthesis of amorphous polyester resin (B1)> (Polycarboxylic acid monomers) Terephthalic acid (TPA) 15 mass parts Fumaric acid (FA) 30 mass parts Dodecenyl succinic acid (DDSA) 3 mass parts Trimellitic acid (TMA) 10 mass parts (Polyhydric alcohol monomers) 2,2-bis(4-phydroxyohenyl) propane- 20 mass parts ethylene oxide adduct (1:2) (BPA-EO) 2,2-bis(4-phydroxyohenyl) propane-propylene 70 mass parts oxide adduct (1:2) (BPA-PO)

(18) Into a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a temperature sensor, and a rectifying column were placed the following polycarboxylic acid monomers and polyhydric alcohol components. The temperature of the reaction mixture was raised to 190 C. over a period of 1 hour. Then, it was confirmed that the reaction system was uniformly stirred. Afterward, Ti(OBu).sub.4 was added as an esterification catalyst (0.004 mass % with respect to the total amount of the polycarboxylic acid monomers). The temperature of the reaction mixture was raised from 190 C. to 240 C. over a period of 6 hours with removing the produced water. The polymerization reaction was done by continuing the dehydration-condensation reaction at 240 C. for 6 hours. Then, the reaction mixture was subjected to a reduced pressure to obtain an amorphous polyester resin (B1). The obtained resin had a weight average molecular weight (Mw) of 21,000

(19) TABLE-US-00004 <Preparation of dispersion liquid of releasing agent particles (W1)> (Polycarboxylic acid monomers) Terephthalic acid (TPA) 60 mass parts Dodecenyl succinic acid (DDSA) 5 mass parts Trimellitic acid (TMA) 7 mass parts (Polyhydric alcohol monomers) 2,2-bis (4-phydroxyohenyl) propane-ethylene 30 mass parts oxide adduct (1:2 ) (BPA-EO) 2,2-bis (4-phydroxyohenyl) propane-propylene 60 mass parts oxide adduct (1:2) (BPA-PO)

(20) Hydrocarbon wax (paraffin wax, HNP-11, made by Nippon Seiro Co., Ltd., melting point of 70 C.): 270 mass parts

(21) Anionic surfactant (Neogen RK, made by DKS Co. Ltd., effective content of 60 mass %): 13.5 mass parts (as an effective component, 3.0 mass % with respect to the releasing agent)

(22) Ion-exchanged water: 21.6 mass parts

(23) The above-described components were mixed. Then, the paraffin wax (releasing agent) was melted in a pressure discharge type Gaulin homogenizer (made by Gaulin Co. ltd.) at an inner temperature of 120 C. Afterward, the mixture was subjected to a dispersion treatment at a dispersion pressure of 5 MPa for 120 minutes, then it was treated at a dispersion pressure of 40 MPa for 360 minutes. Then, the mixture was cooled to obtain a dispersion liquid of releasing agent particles (W1). The dispersion liquid (W1) contained particles having a volume-based median diameter d50 of 225 nm. Subsequently, ion-exchanged water was added to adjust the solid content to be 20.0 mass %.

(24) <Preparation of Dispersion Liquids of Releasing Agent Particles (W2) to (W4)>

(25) Dispersion liquids of releasing particles (W2) to (W4) each were prepared in the same manner as preparation of the dispersion liquid of releasing particle (W1) except that the hydrocarbon wax used as a releasing agent was changed as indicated below.

(26) Dispersion liquid of releasing agent particles (W2): Micro crystalline wax (HNP-0190, made by Nippon Seiro Co., Ltd., melting point of 85 C.)

(27) Dispersion liquid of releasing agent particles (W3): Fischer-Tropsch wax (FNP-0090, made by Nippon Seiro Co., Ltd., melting point of 80 C.)

(28) Dispersion liquid of releasing agent particles (W4): Ester wax (WEP-3, made by Nippon Seiro Co., Ltd., melting point of 73 C.)

(29) <Preparation of Dispersion Liquid of Crystalline Resin (Crystalline Polyester Resin) Particles (CA-1)>

(30) 100 mass parts of the crystalline polyester resin (C1) were dissolved in 400 mass parts of ethyl acetate. Then, 25 mass parts of 5 mass % sodium hydroxide aqueous solution were added to make a resin solution. This resin solution was placed in a reaction vessel equipped with a stirrer. While stirring the resin solution, 400 mass parts of 0.26 mass % sodium lauryl sulfate aqueous solution were added over a period of 30 minutes. On the way of adding the sodium lauryl sulfate aqueous solution, the liquid in the reaction vessel became cloudy. All amount of the sodium lauryl sulfate aqueous solution was dropped, and it was obtained an emulsion dispersion liquid in which were uniformly dispersed the crystalline polyester resin particles containing 20% of solid fraction.

(31) <Preparation of Dispersion Liquid of Crystalline Resin (Crystalline Polyester Resin) Particles (CA-2)>

(32) A dispersion liquid of crystalline resin particles (CA-2) was prepared in the same manner as preparation of the dispersion liquid of crystalline resin particles (CA-1) except that the kind of the crystalline polyester resin was changed from C1 to C2.

(33) <Preparation of Dispersion Liquid of Amorphous Polyester Resin Particles (AA-1)>

(34) A dispersion liquid of amorphous resin particles (AA-1) was prepared in the same manner as preparation of the dispersion liquid of crystalline resin particles (CA-1) except that the crystalline polyester resin (C1) was changed to the amorphous polyester resin (A1).

(35) <Preparation of Dispersion Liquid of Amorphous Polyester Resin Particles (BA-1)>

(36) A dispersion liquid of amorphous resin particles (BA-1) was prepared in the same manner as preparation of the dispersion liquid of crystalline resin particles (CA-1) except that the crystalline polyester resin (C1) was changed to the amorphous polyester resin (B1).

(37) <Preparation of Dispersion Liquid of Coloring Agent Particles (P1)>

(38) (Pre-Treatment)

(39) As a pigment of a coloring agent, C. I. Pigment Yellow 74 was arranged. This pigment was subjected to a pre-treatment of a vacuum heat treatment under the conditions of temperature 100 C. and a vacuum level of 13.3322 Pa.

(40) (Dispersion)

(41) 90 mass parts of sodium lauryl sulfate were added to 1, 600 mass parts of ion-exchanged water. While stirring this solution, 220 mass parts of the pre-treated C. I. Pigment Yellow 74 were gradually added. Subsequently, the solution was subjected to a dispersion treatment using a stirrer CLEARMIX (M Technique Co., Ltd.). Thus a dispersion liquid of coloring agent particles (P1) was obtained. The solid fraction of this dispersion liquid (P1) was 13.0%. A volume-based median diameter of the colorant agent particles in the dispersion liquid was 160 nm. A content of alkoxy aniline (2-methoxy aniline) in C. I. Pigment Yellow 74 was measured to be 300 mass ppm.

(42) <Preparation of Dispersion Liquid of Coloring Agent Particles (P2)>

(43) A dispersion liquid of coloring agent particles (P2) was obtained in the same manner as preparation of the dispersion liquid of coloring agent particles (P1) except that the coloring agent was changed to a mixture of C. I. Pigment Yellow 74 and C. I. Pigment Yellow 155 with a mass ratio of 1:0.4, wherein C. I. Pigment Yellow 155 was subjected to the same pre-treatment as done to C. I. Pigment Yellow 74.

(44) <Preparation of Dispersion Liquid of Coloring Agent Particles (P3)>

(45) A dispersion liquid of coloring agent particles (P3) was obtained in the same manner as preparation of the dispersion liquid of coloring agent particles (P1) except that the coloring agent was changed to C. I. Pigment Yellow 74 without subjected to the pre-treatment as described above.

(46) <Preparation of Dispersion Liquid of Coloring Agent Particles (P4)>

(47) A dispersion liquid of coloring agent particles (P4) was obtained by adding 80 mass parts of 2-ethoxy aniline to the dispersion liquid of coloring agent particles (P1).

(48) <Preparation of Dispersion Liquid of Coloring Agent Particles (P5)>

(49) A dispersion liquid of coloring agent particles (P5) was obtained in the same manner as preparation of the dispersion liquid of coloring agent particles (P1) except that the coloring agent was changed to C. I. Pigment Yellow 155 without subjected to the pre-treatment as described above in place of C. I. Pigment Yellow 74, and further by adding 200 mass parts of 2-methoxy aniline.

(50) <Preparation of Dispersion Liquid of Coloring Agent Particles (P6)>

(51) A dispersion liquid of coloring agent particles (P6) was obtained in the same manner as preparation of the dispersion liquid of coloring agent particles (P1) except that the coloring agent was changed to C. I. Pigment Yellow 155 without subjected to the pre-treatment as described above in place of C. I. Pigment Yellow 74.

(52) <Preparation of Dispersion Liquid of Coloring Agent Particles (P7)>

(53) A dispersion liquid of coloring agent particles (P7) was obtained in the same manner as preparation of the dispersion liquid of coloring agent particles (P1) except that the coloring agent was changed to C. I. Pigment Yellow 155 without subjected to the pre-treatment as described above in place of C. I. Pigment Yellow 74, and further by adding 400 mass parts of 2-methoxy aniline.

(54) In Table 1, there are listed the kinds of the coloring agents in the dispersion liquids of coloring agent particles (P1 to P7), the kind and the amount of the alkoxy aniline in the dispersion liquids. In Table 1, C. I. Pigment Yellow 74 is described as PY74, C. I. Pigment Yellow 155 is described as PY155, 2-methoxy aniline is described as MA, and 2-ethoxy aniline is described as EA.

(55) <Preparation of Toner (1)>

(56) Into a reaction vessel equipped with a stirrer, a temperature sensor and a cooling tube, 100 mass parts (in solid fraction) of the dispersion liquid of the amorphous polyester resin particles (AA-1), 80 mass parts (in solid fraction) of the dispersion liquid (BA-1) of the amorphous polyester resin particles, and 2,000 mass parts of ion-exchanged water were charged. Thereafter, while mixing the mixture at 20 C., the pH was adjusted to 10 by adding 5 mol/L sodium hydroxide aqueous solution.

(57) Further, there were 6.2 mass parts (in solid fraction) of the dispersion liquid of the coloring agent particles (P1) were added. Then, while stirring, an aqueous solution of 60 mass parts of magnesium chloride dissolved in 60 mass parts of ion-exchanged water were added at 30 C. over a period of 10 minutes. After leaving the mixture for 3 minutes, 20 mass parts (in solid fraction) of the aqueous dispersion liquid of the crystalline polyester resin particles (CA-1) were added over a period of 10 minutes. Then, the temperature of the system was raised to 82 C. over a period of 60 minutes, and the temperature was held at 82 C. to allow the particle growth reaction to continue.

(58) While keeping this condition, the particle size of the aggregated particles was measured by using a Coulter Multisizer 3 (Beckman Coulter, Inc.). When the volume based median particle size reached 6.0 m, an aqueous solution containing 190 mass parts of sodium chloride dissolved in 760 mass parts of ion-exchanged water was added to terminate the particle growth. Then, the reaction system was further stirred at 74 C. to allow fusion of the particles to proceed. When the average circularity of the toner reached 0.957, the reaction system was cooled to 30 C. at a cooling rate of 2.5 C./min. The average circularity of the toner was measured by a measuring apparatus FPIA-2100 (Sysmex Corp.) (HPF detect number of 4,000).

(59) Then, solid-liquid separation was carried out, and a dewatered toner cake was washed by repeating re-dispersion in ion-exchanged water and solid-liquid separation for 3 times. Thereafter, the toner cake was dried at 40 C. for 24 hours to obtain toner mother particles.

(60) To 100 mass parts of the obtained toner mother particles were added 0.6 mass parts of hydrophobic silica (number average primary particle size=12 nm, hydrophobicity=68) and 1.0 mass parts of hydrophobic titanium oxide (number average primary particle size=20 nm, hydrophobicity=63). The mixture was blended by using a Henschel mixer (Nippon Coke & Engineering Co., Ltd.) with a rotary blade circumferential speed of 35 mm/sec at 32 C. for 20 minutes. Thereafter, the coarse particles were removed with a sieve having a mesh of 45 m. Thus, it was prepared a toner (1) treated with an external additive.

(61) <Preparation of Toners (2) to (12)>

(62) Toners (2) to (12) each were prepared in the same manner as preparation of the toner (1) except that the combination of the dispersion liquids were changed as indicated in Table 1.

(63) <Preparation of Electrostatic Image Developing Developers (1) to (12)>

(64) 100 mass parts of ferrite core and 5 mass parts of copolymer resin particles made of cyclohexyl methacrylate/methylmethacrylate (copolymerization ratio of 1:1) were placed in a high speed mixer provided with a stirring blade. The mixture was stirred at 120 C. from 30 minutes to form a resin coat layer on a surface of a ferrite core with a mechanical force effect. Thus it was obtained a carrier having a volume-based median diameter (d.sub.50) of 35 m.

(65) The volume-based median diameter (d.sub.50) of the carrier was measured by using a laser diffraction system particle size distribution meter HELOS (produced by SYMPATEC Co.) provided with a wet type dispersing apparatus. To the above-described carrier was added each of the toners (1) to (12) so that the content of the toner became to be 6 mass %. The mixtures each were loaded in a micro V-shape mixer (made bay Tsutsui Scientific Instrument Co. Ltd.), and they were mixed with a rotation rate of 45 rpm for 30 minutes to prepare developers (1) to (12).

(66) TABLE-US-00005 Coloring agent Dispersion liquid Alkoxy aniline Amount of Addition Crystaline dispersion Added Total polyester resin liquid Kind in amount content Acid Toner (mass Pre- coloring (mass (mass value Content number Number Kind parts) treatment agent Kind ppm) ppm) Kind (mg KOH/g (mass %) 1 P1 PY74 6.2 Done MA 300 C1 20 10 2 P1 PY74 6.2 Done MA 300 C1 20 10 3 P1 PY74 6.2 Done MA 300 C1 20 10 4 P1 PY74 6.2 Done MA 300 C1 20 10 5 P1 PY74 6.2 Done MA 300 C2 20 10 6 P2 PY74 6.2 Done MA 90 C1 20 10 PY155 (*1) 7 P4 PY74 5.5 Done MA EA 80 340 C1 20 10 8 P5 PY155 6.2 Not MA 200 200 C1 20 10 Done 9 P2 PY74 3.0 Done MA 40 C1 20 10 PY155 (*1) 10 P6 PY155 5.5 Not 0 C1 20 10 Done 11 P7 PY155 12.0 Not MA 400 400 C1 20 10 Done 12 P3 PY74 6.2 Not MA 800 C1 20 10 Done Amorphous resin Acid Releasing High value Low agent Toner molecular (mg molecular Melting number component KOH/g) component Kind point ( C.) 2 Remarks 1 A1 15 B1 W1 70 14 Inv. 2 A1 15 B1 W2 85 15 Inv. 3 A1 15 B1 W3 80 14 Inv. 4 A1 15 B1 W4 73 15 Inv. 5 A1 15 B1 W1 70 14 Inv. 6 A1 15 B1 W1 70 5 Inv. 7 A1 15 B1 W1 70 15 Inv. 8 A1 15 B1 W1 70 11 Inv. 9 A1 15 B1 W1 70 2 Inv. 10 A1 15 B1 W1 70 0 Comp. 11 A1 15 B1 W1 70 20 Comp. 12 A1 15 B1 W1 70 17 Comp. (*1) PY74 and PY155 were used with a ratio of 1:1 (*2) Content (mass ppm) of alkoxy aniline in toner particles Inv. = Inventive example Comp. = Comparative example
<Evaluation Methods>

(67) Low-temperature fixing property and toner scattering of the toners were respectively evaluated.

(68) (Evaluation of Low-Temperature Fixing Property)

(69) As an image-forming apparatus, it was used a multi-function printer Bizhub C754 (made by Konica Minolta, Inc.) with modifying the fixing device in such a manner that the surface temperature of the fixing upper belt and the fixing under roller was adjustable. The developers produced by using the toners were respectively charged to the apparatus. As a paper for evaluation, mondi Color Copy A4 90 g/m.sup.2 (made by Mondi Co. Ltd.) was used. A fixing test was repeatedly conducted to fix a solid image having an amount of adhered toner of 11.3 g/m.sup.2 under the conditions of: nip width of 11.2 mm, fixing time of 34 msec, fixing pressure of 133 kPa, and fixing temperature from 100 C. to 200 C. by changing the fixing temperature with a step of 5 C. The fixing tests were repeated until the moment of appearing cold offset. The lowest surface temperature of the fixing upper belt without producing cold offset was checked. This temperature was recorded as a lowest fixing temperature and the low-temperature fixing property was evaluated. The evaluation results are listed in Table 2. Here, in the evaluation test, a fixing temperature indicates a surface temperature of the fixing upper belt. When the lowest fixing temperature is smaller, it indicates that it is excellent in the low-temperature fixing property.

(70) In the present evaluation, when the lowest fixing temperature was 160 C. or less, it was decided that the developer passed the examination.

(71) (Evaluation of Scattering Property)

(72) As an evaluation apparatus, it was used a modified multi-function printer Bizhub C754 (made by Konica Minolta, Inc.). After making 100,000 sheets of prints, the developing device was taken out, and it was set to a rotary device. An A4 white paper was set under the developing sleeve by locating the position of the developing sleeve in the center of the paper. The developing sleeve was rotated for 60 minutes, and the mass of the fallen toner (toner scattering amount) was measured to evaluate. The rotation circumferential speed of the developing sleeve was made to be 620 mm/sec. When the toner scatting amount was 9 mg or less, it was decided that the developer passed the examination. The evaluation results are listed in Table 2.

(73) TABLE-US-00006 TABLE 2 Low-temperature fixing property Scattering property Lowest fixing Toner scattering Toner temperature amount number ( C.) (mg) Remarks 1 145 3 Inv. 2 150 4 Inv. 3 150 4 Inv. 4 145 5 Inv. 5 155 7 Inv. 6 155 7 Inv. 7 145 9 Inv, 8 140 8 Inv. 9 140 5 Inv. 10 165 2 Comp. 11 145 11 Comp. 12 145 13 Comp. Inv. = Inventive example Comp. = Comparative example

(74) As indicated in Table 2, it was found that the toners according to the present invention exhibited an excellent low-temperature fixing property and a small amount of toner scattering. On the other hand, the comparative toners were found to exhibit an inferior result in at least one of low-temperature fixing property and toner scattering property.