YELLOW TONER

Abstract

Provided is a yellow toner which provides a sharper color than ever before in small amounts and which has excellent light resistance. A yellow toner comprising a binder resin and a yellow colorant, wherein a compound A represented by the following general formula (1) and a compound B represented by the following general formula (2) are contained as the yellow colorant,, and wherein a total content of the compound A and the compound B is from 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin, and a mass ratio of the content of the compound A to the content of the compound B (compound A/compound B) is from 0.8 to 20:

##STR00001##

Claims

1. A yellow toner comprising a binder resin and a yellow colorant, wherein a compound A represented by the following general formula (1) and a compound B represented by the following general formula (2) are contained as the yellow colorant, and wherein a total content of the compound A and the compound B is from 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin, and a mass ratio of the content of the compound A to the content of the compound B (compound A/compound B) is from 0.8 to 20: ##STR00015## where R.sup.1A, R.sup.1B, R.sup.2A and R.sup.2B are each independently a halogen atom, an alkyl group, a methoxy group, an amino group, a nitro group, an acetylamido group (NHCOCH.sub.3), a methyl ester group (COOCH.sub.3) or a primary amide group (CONH.sub.2); R.sup.3 is a halogen atom; R.sup.4 and R.sup.5 are each independently a halogen atom, an alkyl group, a methoxy group, an amino group, a nitro group, an acetylamido group (NHCOCH3), an acetyl group (COCH.sub.3), a methyl ester group (COOCH.sub.3) or a primary amide group (CONH.sub.2); a1 and b1 are positive integers that a sum of the positive integers is 1 or more and 3 or less; a2 and b2 are positive integers that a sum of the positive integers is 1 or more and 3 or less; c is an integer of 1 or more and 3 or less; and d and e are each independently 1 or 2, ##STR00016## where R.sup.6 is an alkyl group.

Description

EXAMPLES

[0113] Hereinafter, the present invention will be described further in detail, with reference to examples and comparative examples. However, the scope of the present invention may not be limited to the following examples. Herein, part(s) and % are based on mass if not particularly mentioned.

1. Production of Colored Resin Particles

<Colored Resin Particles (1)>

1-1. Preparation of Polymerizable Monomer Composition for Core

[0114] The following raw materials were subjected to wet pulverization by means of a media-type disperser (product name: PICO MILL, manufactured by: Asada Iron Works Co., Ltd.): 75 parts of styrene, 25 parts of n-butyl acrylate, 0.1 part of a polymethacrylic acid ester macromonomer (product name: AA6, manufactured by: TOAGOSEI Co., Ltd., Tg: 94 C.), 0.7 part of divinylbenzene, 1.0 part of tetraethylthiuram disulfide and, as yellow colorant, 6parts of C.I. Pigment Yellow 214 (represented by the following formula (1A), product name: PV Fast Yellow H9G VP2430, manufactured by: Clariant Corp., CAS No. 254430-12-5) and 4 parts of C.I. Solvent Yellow 98 (product name: Hostasol Yellow 3G, manufactured by: Clariant Corp., CAS No. 12671-74-8). To a mixture obtained by the wet pulverization, 1.2 parts of a charge control resin (product name: Acrybase FCA-161P, manufactured by: Fujikura Kasei Co., Ltd.) and 10 parts of an ester wax (product name: WEP7, manufactured by: NOF Corporation) were added, mixed and dissolved to obtain a polymerizable monomer composition.

##STR00011##

1-2. Preparation of Aqueous Dispersion Medium

[0115] An aqueous solution of 7.3 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water, was gradually added to an aqueous solution of 10.4 parts of magnesium chloride dissolved in 280 parts of ion-exchanged water, while stirring, thereby preparing a magnesium hydroxide colloid dispersion.

1-3. Preparation of Polymerizable Monomer for Shell

[0116] Meanwhile, 2 parts of methyl methacrylate and 130 parts of water were subjected to a fine dispersion treatment by means of an ultrasonic emulsifying machine, thereby preparing an aqueous dispersion of a polymerizable monomer for shell.

1-4. Droplets Forming Process

[0117] The polymerizable monomer composition was put in the magnesium hydroxide colloid dispersion (the magnesium hydroxide colloid amount: 5.3 parts) and stirred. Then, as a polymerization initiator, 6 parts of t-butylperoxy-2-ethylhexanoate was added thereto. The dispersion containing the polymerization initiator was subjected to dispersion at 15,000 rpm using an in-line type emulsifying and dispersing machine (product name: Milder, manufactured by: Pacific Machinery & Engineering Co., Ltd.), thereby forming the polymerizable monomer composition into droplets.

1-5. Suspension Polymerization Process

[0118] The dispersion containing the droplets of the polymerizable monomer composition was put in a reactor. The temperature thereof was increased to 90 C. to start a polymerization reaction. After the polymerization conversion rate reached almost 100%, a solution obtained by dissolving 0.1 part of 2,2-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] (a water-soluble polymerization initiator, product name: VA-086, manufactured by: Wako Pure Chemical Industries, Ltd.) in the aqueous dispersion for the polymerizable monomer for shell, was added in the reactor. Next, the temperature of the reactor was kept at 95 C. for 4 hours to continue the polymerization further. Then, the reactor was cooled by water to stop the reaction, thereby obtaining an aqueous dispersion of core-shell type colored resin particles.

1-6. Post-Treatment Process

[0119] The aqueous dispersion of the colored resin particles was subjected to acid washing (25 C., 10 minutes) in which, while stirring the aqueous dispersion, sulfuric acid was added thereto until the pH of the aqueous dispersion was 4.5 or less. Then, the colored resin particles were separated from the aqueous dispersion by filtration and washed with water. The washing water was filtered. A filtrate thus obtained had an electrical conductivity of 20 S/cm. The colored resin particles subjected to the washing and filtering processes were dehydrated and dried to obtain dried colored resin particles (1).

[0120] <Colored Resin Particles (2)>

[0121] Colored resin particles (2) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, the added amount of C.I. Pigment Yellow 214 was changed from 6 parts to 10 parts, and the added amount of C.I. Solvent Yellow 98 was changed from 4 parts to 2 parts.

<Colored Resin Particles (3)>

[0122] Colored resin particles (3) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, the added amount of C.I. Pigment Yellow 214 was changed from 6 parts to 10 parts.

<Colored Resin Particles (4)>

[0123] Colored resin particles (4) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, 4 parts of C.I. Solvent Yellow 98 was changed to 4 parts of C.I. Solvent Yellow 162 (represented by the following formula (X), product name: NEPTUN YELLOW 075, manufactured by: BASF, CAS No. 104244-10-2).

##STR00012##

<Colored Resin Particles (5)>

[0124] Colored resin particles (5) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, 4 parts of C.I. Solvent Yellow 98 was changed to 4 parts of C.I. Solvent Yellow 93 (represented by the following formula (Y), product name: Solvaperm Yellow 3G, manufactured by: Clariant Corp., CAS No. 4702-90-3).

##STR00013##

<Colored Resin Particles (6)>

[0125] Colored resin particles (6) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, 4 parts of C.I. Solvent Yellow 98 was changed to 4 parts of C.I. Solvent Yellow 114 (represented by the following formula (Z), product name: Solvaperm Yellow 2G, manufactured by: Clariant Corp., CAS No. 7576-65-0).

##STR00014##

<Colored Resin Particles (7)>

[0126] Colored resin particles (7) were obtained in the same manner as the production method of the colored resin particles (1), except that in the Preparation of polymerizable monomer composition for core, the added amount of C.I. Pigment Yellow 214 was changed from 6 parts to 8 parts, and 4 parts of C.I. Solvent Yellow 98 was not used.

2. Evaluation of Properties of Colored Resin Particles

[0127] Measurement of volume average particle diameter (Dv) and calculation of particle size distribution (Dv/Dn) were carried out on the colored resin particles (1) to (7).

[0128] First, 0.1 g of a measurement sample (colored resin particles) was weighed, out and put in a beaker. As a dispersant, 0.1 mL of an alkylbenzene sulfonic acid aqueous solution (product name: Driwel, manufactured by: Fujifilm Corporation) was added thereto. In addition, 10 to 30 mL of Isoton II was added to the beaker. The mixture was dispersed for three minutes with a 20W ultrasonic disperser. Then, the volume average particle diameter (Dv) and number average particle diameter (Dn) of the colored resin particles were measured with a particle diameter measuring device (product name: Multisizer, manufactured by: Beckman Coulter, Inc.) in the following conditions:

[0129] Aperture diameter: 100 m

[0130] Medium: Isoton II

[0131] Number of measured particles: 100,000

Next, the particle size distribution (Dv/Dn) of the colored resin particles was calculated.

3. Production of Yellow Toner

[0132] The colored resin particles (1) to (7) were covered with external additives to produce yellow toners of Examples 1 to 3 and Comparative Examples 1 to 4.

Example 1

[0133] First, 0.6 part of hydrophobized silica fine particles having an average particle diameter of 7 nm and 1 part of hydrophobized silica fine particles having an average particle diameter of 35 nm, were added to 100 parts of the colored resin particles (1). They were mixed by means of a high-speed stirrer (product name: FM Mixer, manufactured by: Nippon Coke & Engineering Co., Ltd.) to prepare the yellow toner of Example 1.

Examples 2 and 3 and Comparative Examples 1 to 4

[0134] The yellow toners of Examples 2 and 3 and Comparative Examples 1 to 4 were obtained in the same manner as Example 1, except that the colored resin particles (1) were changed to, as shown in the following Table 1, any of the colored resin particles (2) to (7).

4. Evaluation of Toners for Developing Electrostatic Images

[0135] The charge amount, reflection density (image density), luminance (L*), color coordinate (a*, b*) and chroma (C*) of the yellow toners of Examples 1 to 3 and Comparative Examples 1 to 4, were measured as follows. Also, the light resistance of the yellow toners was evaluated as follows.

4-1. Measurement of Charge Amount

[0136] The toner cartridge of a commercially-available, non-magnetic one-component development printer (product name: MFC-9840-CDW, manufactured by: Brother Industries, Ltd.) was filled with a sample yellow toner, and printing sheets were loaded in the printer. Then, the printer was left to stand under an environment at a temperature of 23 C. and a humidity of 50% (NN environment) for one day. Then, under the same NN environment, solid pattern printing (image density: 0%) was carried out on one sheet. When printing halfway, the printer was stopped. The toner supported on the developing roller was suctioned using a suction type Q/m analyzer (product name: 210HS-2A, manufactured by: TREK JAPAN) to measure the charge amount of the toner. The measured charge amount was converted, into the charge amount Q/M (C/g) per unit mass of the toner.

4-2. Measurement of reflection density, luminance, color coordinate and chroma

[0137] A commercially-available, non-magnetic one-component development color printer (printing rate: 20 sheets/min) was used. The toner cartridge of the development device was filled with a sample yellow toner, and printing sheets were loaded in the printer. Then, the printer was left to stand under an (N/N) environment at a temperature of 23 C. and a relative humidity of 50% for one day. Then, while the amount of the toner supplied onto the developing roller in solid pattern printing was fixed at 0.3 mg/cm.sup.2, sheets were continuously printed at an image density of 5%. Solid pattern printing (image density: 100%) was carried out on the tenth sheet. Using a McBeth transmitting image densitometer, the reflection density (image density), luminance (L*), color coordinate (a*, b*) and chroma(C*) of the tenth sheet were measured.

4-3. Evaluation of Light Resistance

[0138] The light resistance of the toner was evaluated based on a reflection density decrease rate obtained from the value of the reflection density obtained in the above 4-2. Measurement of reflection density, luminance, color coordinate and chroma and the value of the reflection density obtained after the printer was left to stand for a long period of time (560 hours).

[0139] The same color printer as above was used. The toner cartridge of the development device was filled with a sample yellow toner, and printing sheets were loaded in the printer. Then, the printer was left to stand under an (N/N) environment at a temperature of 23 C. and a relative humidity of 50% for 560 hours. Then, in the same condition, sheets were continuously printed, and solid pattern printing (image density: 100%) was carried out on the tenth sheet. Using a McBeth transmitting image densitometer, the reflection density (image density) of the tenth sheet was measured. A reflection density decrease rate was obtained by the following formula, using, as just described, the value (ID.sup.560) of the reflection density (image density) obtained after the printer was left to stand for 560 hours, and the value (ID.sub.ON) of the reflection density (image density) obtained in the above 4-2. Measurement of reflection density, luminance, color coordinate and chroma.

(Reflection density decrease rate)={(ID.sub.ON-ID.sub.560)/ID.sub.ON}100 (%)

[0140] From the reflection density decrease rate thus obtained, the light resistance of the toner was evaluated in accordance with the following evaluation criteria.

[0141] o; The reflection density decrease rate is less than 8%.

[0142] x: The reflection density decrease rate is 8% or more.

[0143] Table 1 shows the measurement and evaluation results of the yellow toners of Examples 1 to 3 and Comparative Examples 1 to 4, along with the toner composition.

[0144] In the following Table 1, PY2.14 means C.I. Pigment Yellow 214; SY98 means C.I. Solvent Yellow 98; SY162 means C.I. Solvent Yellow 162; SY93 means C.I. Solvent Yellow 93; and SY114 means C.I. Solvent Yellow 114. Also, Compound A+compound B (parts) means the sum of the added amount of the compound A and that of the compound B.

TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Example 4 Colored resin Particles (1) Particles (2) Particles (3) Particles (4) Particles (5) Particles (6) Particles (7) particles Compound A PY214 PY214 PY214 PY214 PY214 PY214 PY214 Added amount 6 10 10 6 6 6 8 (parts) Compound B SY98 SY98 SY98 Added amount 4 2 4 (arts) Compound A + 10 12 14 6 6 6 8 compound B (parts) Ratio of 1.5 5.0 2.5 compound A/compound B Other yellow SY162 SY93 SY114 pigment Added amount 4 4 4 (parts) Dv (m) 6.0 5.4 5.5 5.8 5.9 11.1 12.9 Dv/Dn 1.19 1.23 1.21 1.17 1.28 2.34 1.37 Charge 28 25 34 26 8 13 15 amount (C/g) Printing evaluation Amount of 0.3 0.3 0.3 0.3 0.3 0.3 0.3 toner on sheet (mg/cm.sup.2) Reflection 1.15 1.10 1.17 1.38 1.24 1.05 density Luminance L* 94.7 98.7 93.2 95.4 94.3 95.4 a* 6.5 11.7 7.5 11.9 8.7 10.9 b* 90.6 88.7 89.7 87.5 81.5 69.7 Chroma C* 90.8 89.5 90.0 88.3 81.9 70.5 Hue angle () 94.1 97.5 94.6 97.8 96.1 98.9 Light resistance evaluation Reflection x x density decrease rate

5. Evaluation of Toners

[0145] The yellow toner of Comparative Example 1 is a toner using the compound A (C.I. Pigment Yellow 214) in combination with C.I. Solvent Yellow 162. For Comparative Example 1, the chroma C* is as low as 88.3, and the light resistance evaluation result is x. Therefore, it is

[0146] clear that the yellow toner is dull in color and poor in light resistance when C.I. Solvent Yellow 162 is used in place of the compound B, and the toner on the sheet is 0.3 mg/cm.sup.2 and smaller than ever before.

[0147] The yellow toner of Comparative Example 2 is a toner using the compound A (C.I. Figment Yellow 214) in combination with C.I. Solvent Yellow 93. For Comparative Example 2, the charge amount is as low as 8 C/g. Since the toner was negatively charged, toner particles with originally expected charging ability were not obtained, and a toner that was worthy of printing evaluation was not obtained. Therefore, printing evaluation of the toner was cancelled.

[0148] The yellow toner of Comparative Example 3 is a toner using the compound A (C.I. Figment Yellow 214) in combination with C.I. Solvent Yellow 114. For Comparative Example 3, the volume average particle diameter (Dv) is as large as 11.1 m, and the particle size distribution (Dv/Dn) is 2.34. Accordingly, the yellow toner of Comparative Example 3 is a toner with a wide particle size distribution. Also, the light resistance evaluation result is x. From these results, it is clear that when C.I. Solvent Yellow 114 is used in place of the compound B, the particle diameter of the toner thus obtained increases overall; the toner particles are non-uniform in particle diameter; and the toner thus obtained is poor in light resistance.

[0149] The yellow toner of Comparative Example 4 is a toner in which 8.0 parts by mass of the compound A is only used as the yellow colorant with respect to 100 parts by mass of the binder resin. For Comparative Example 4, the volume average particle diameter (Dv) is as large as 12.9 m, and the particle size distribution (Dv/Dn) is 1.37. Accordingly, the yellow toner of Comparative Example 3 is a toner with a wide particle size distribution. From these results, it is clear that when the compound B is not used, the particle diameter of the toner thus obtained increases overall, and the toner particles are non-uniform in particle diameter.

[0150] Also for Comparative Example 4, the chroma C* is as low as 70.5. This value is the lowest among the evaluated toners. Therefore, it is clear that the yellow toner is especially dull in color when the compound A is used solely as the yellow colorant, and the toner on the sheet is 0.3 mg/cm.sup.2 and smaller than ever before.

[0151] Meanwhile, the yellow toners of Examples 1 to 3 are toners in which the total content of the compound A and the compound B is from 10 to 14 parts by mass with respect to 100 parts by mass of the binder resin, and the mass ratio of the content of the compound A to the content, of the compound B (compound A/compound B) is from 1.5 to 5.0. For Examples 1 to 3, the volume average particle diameter (Dv) is as small as 5.4 to 6.0 m, and the particle size distribution (Dv/Dn) is as narrow as 1.19 to 1.23. Therefore, it is clear that the toners of Examples 1 to 3have the desired particle diameter and are narrow in particle size distribution.

[0152] Also for Examples 1 to 3, the chroma C* is as high as 89.5 or more, and the light resistance evaluation result is o. Therefore, it is clear that even when the toner on the sheet is 0.3 mg/cm.sup.2 and smaller than ever before, the yellow toners of Examples 1 to 3 (in which the total content of the compounds A and B contained as the yellow colorant is from 3 to 30 parts by mass with respect to 100 parts by mass of the binder resin, and the mass ratio of the content of the compound A to the content of the compound B (compound A/compound B) is from 0.8 to 20) are each a toner which provides a sharper color than ever before and which has excellent light resistance.