JP2007286254A - Black toner for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a black toner for electrophotography that reuses color toners recovered from the manufacturing process of color toners or from a color image forming process and exerts excellent fog characteristics, fixing property and durability without causing a color shift. <P>SOLUTION: The black toner for electrophotography is manufactured by mixing a source material containing a binder resin and a black colorant, melting and kneading, cooling, and then pulverizing and classifying, is characterized in that: at least one kind in a fine powder magenta toner recovered from the manufacturing process of a magenta toner, a fine powder cyan toner recovered from the manufacturing process of a cyan toner and a fine powder yellow toner recovered from the manufacturing process of a yellow toner is added to the source material; the add amount of the fine powder magenta toner is 10 parts by mass or less; the add amount of the fine powder cyan toner is 15 parts by mass or less; the add amount of the fine powder yellow toner is 15 parts by mass or less; and the total of the add amounts is 30 mass% or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a black toner for electrophotography, and more particularly, to a black toner for electrophotography in which color toner collected from a toner manufacturing process and an image forming process is reused.

  In general, image formation by an electrophotographic method is performed by developing an electrostatic image with a toner to make it visible, and transferring the toner image obtained by the development to a sheet. The toner used for such image formation includes a dry toner and a wet toner, and a dry toner manufacturing method includes a pulverization method and a polymerization method.

  In the toner manufacturing process by the pulverization method, fine powder toner is generated particularly in the pulverization and classification steps. As a method of reusing the fine powder toner (not added), the collected fine powder toner is returned to the mixing step or melt-kneading so as to obtain a mixing ratio of 5 to 10% by mass, thereby increasing the yield as a material. A method has been proposed (see, for example, Patent Document 1). However, this method does not reuse color toner.

  It has also been proposed to mix the color toner collected by the image forming apparatus with black toner at a ratio of 60% by mass or less and reuse it in the same image forming apparatus (for example, see Patent Document 2). However, this method has a demerit that it is necessary to change the developing device and the collection / control mechanism is complicated.

  Furthermore, a method has also been proposed in which resin particles carrying or containing inorganic fine particles collected in the toner manufacturing process are returned to the mixing process to form toner (see, for example, Patent Document 3). As described above, the advantage of recycling the resin particles containing inorganic fine particles is that the dispersibility during mixing of the raw materials is improved, so that the developing property and durability of the toner are good, the fog is small, and the transfer is not damaged. It is said that toner that does not occur is obtained.

However, this method does not relate to a color toner, and has a demerit that image fogging occurs when the component of the fine toner is greatly different from the component constituting the toner.
JP-A-10-010780 JP-A-8-63067 JP-A-6-258870

  The present invention has been made under the circumstances as described above, and reuses the color toner collected from the color toner manufacturing process or the color image forming process, and has excellent fog characteristics, fixability and durability without causing color misregistration. An object of the present invention is to provide a black toner for electrophotography exhibiting properties.

  In order to solve the above problems, a first aspect of the present invention is an electrophotographic black produced by mixing a raw material containing a binder resin and a black colorant, melt kneading, cooling, pulverizing and classifying. The toner includes at least a fine powder magenta toner collected from a magenta toner production process, a fine powder cyan toner collected from a cyan toner production process, and a fine powder yellow toner collected from a yellow toner production process. 1 type is added, the addition amount of the fine powder magenta toner is 10 parts by mass or less, the addition amount of the fine powder cyan toner is 15 parts by mass or less, and the addition amount of the fine powder yellow toner is 15 parts by mass. An electrophotographic black toner is provided, wherein the total amount of addition is 30% by mass or less.

  A second aspect of the present invention is a black toner for electrophotography produced by mixing raw materials containing a binder resin and a black colorant, melt-kneading, cooling, pulverizing and classifying, and At least one of magenta toner, cyan toner, and yellow toner recovered from a color image forming process is added to the raw material, and the amount of the recovered magenta toner added is 10 parts by mass or less, and the amount of the recovered cyan toner added Is 15 parts by mass or less, and the addition amount of the recovered yellow toner is 15 parts by mass or less, and the total addition amount is 30% by mass or less.

  According to the present invention, by reusing a predetermined amount of fine powder toner and color toner containing different colorants collected from the color toner manufacturing process or color image forming process to the black toner manufacturing process, Thus, an electrophotographic black toner having excellent characteristics free from color shift and fogging can be obtained.

  The best mode for carrying out the invention will be described below.

  In the black toner for electrophotography according to an embodiment of the present invention, a predetermined amount of fine powder color toner from the color toner manufacturing process or a predetermined amount of recovered color toner from the color image forming process is used in the raw material mixing step of the black toner. It is characterized by being added.

  The fine powder color toner includes fine powder magenta toner collected from the magenta toner manufacturing process, fine powder cyan toner collected from the cyan toner manufacturing process, and fine powder yellow toner collected from the yellow toner manufacturing process. Any one or a mixture of two or more of these fine powder color toners can be used.

  For example, when classifying pulverized color toners with a cyclone, the cyclone exhaust is drawn with a common blower for each color toner to adjust the pressure balance, but at that time, the fine powder is collected and collected. The Such a fine powder mixture cannot be returned to the color toner manufacturing process, but can be returned to the black toner manufacturing process and reused within a predetermined addition amount range.

  The amount added to the black toner raw material mixing step is 10 parts by mass or less for fine powder magenta toner, 15 parts by mass or less for fine powder cyan toner, and 15 parts by mass or less for fine powder yellow toner. Moreover, the total amount of addition amount is 30 mass% or less.

  If the addition amount exceeds these ranges, the black toner will cause a color shift.

  Examples of the recovered color toner include residual magenta toner, residual cyan toner and residual yellow toner recovered from the color developing device, or waste magenta toner, waste cyan toner and waste yellow toner recovered from the transfer device of the color image forming apparatus. is there. Any one or a mixture of two or more of these recovered color toners can be used.

  The amount added to the black toner raw material mixing step is 10 parts by mass or less for the recovered magenta toner, 15 parts by mass or less for the recovered cyan toner, and 15 parts by mass or less for the recovered yellow toner. Moreover, the total amount of addition amount is 30 mass% or less.

  If the addition amount exceeds these ranges, the black toner will cause a color shift.

The black toner manufacturing method according to an embodiment of the present invention is performed as follows in accordance with the process shown in FIG.
First, black toner raw materials such as a binder resin, a colorant, and a release agent are mixed with a mixer. As a mixing machine, arbitrary things, such as a Henschel mixer, a super mixer, a V-type blender, and a Nauta mixer, can be used.

  In this mixing process, the fine magenta toner collected from the magenta toner manufacturing process, the fine cyan toner collected from the cyan toner manufacturing process, and the fine yellow toner collected from the yellow toner manufacturing process are weighed and added. The amount is adjusted to a predetermined amount or less for each fine color toner and then added.

  The magenta toner manufacturing process, cyan toner manufacturing process, and yellow toner manufacturing process all include raw material mixing, melt-kneading, cooling, pulverization, classification, and external addition processes. The recovered particle size is not more than a predetermined particle size, for example, the average particle size is 5 μm or less.

  The raw material mixture to which fine powder toner has been added is then fed to a kneader where it is melt kneaded. Although it does not specifically limit as a kneader, For example, a biaxial kneader, an open roll type kneader, etc. can be used. As an open type kneader, any type such as a continuous two-roll mill, a continuous three-roll mill, and a batch-type roll mill can be used.

  The melt-kneaded product discharged from the kneader is usually cooled, pulverized, and classified to a predetermined particle size according to a method used for producing a toner to obtain a toner particle matrix. The cooling means, the pulverizing means, and the classification means are not particularly limited, and those usually used for toner production can be employed. For example, a cooling means by rolling or air flow spraying can be used for cooling, and an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. Can be used.

  An electrophotographic black toner is obtained by adding an external additive such as silica to the toner particle matrix thus obtained, and mixing and stirring.

  The obtained black toner has fine powder color toner added thereto, but since the amount thereof is limited, color misregistration does not occur and is excellent in fog characteristics, fixability and durability.

  In the above, the case where the fine color toner collected from the color toner manufacturing process is reused has been described. However, the color toner collected from the color image forming process can be reused as well.

  Hereinafter, production examples of recycled toner and reference black toner used in Examples and Comparative Examples of the present invention will be described.

Production Example 1 (Recycled toner)
(A) Recycled magenta toner 100 parts by mass of polyester resin (manufactured by Kao Corporation: Tg: 65 ° C./Tm: 140 ° C.), 3 parts by mass of Carmine 6B “No. 27” (manufactured by Fuji Dye Co., Ltd.) as a colorant , 4 parts by weight of Carnauba Wax No. 1 powder (manufactured by Kato Yoko) as a release agent, and 1 part by weight of E-84 (manufactured by Orient Chemical Co., Ltd.) as a charge control agent Manufactured and equipped with standard blades), and stirred and mixed for 4 minutes at a blade peripheral speed of 20 m / sec.

  The obtained mixed powder is melt-kneaded with a twin screw extruder, stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Co., Ltd., 2 mm screen). The fine particles were obtained by pulverization and classification so that the average particle diameter of the toner was 9.0 μm.

  2 parts by mass of “RY200” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) as an external additive is added to 100 parts by mass of the obtained fine particles, and Henschel mixer (manufactured by Mitsui Mining Co., Ltd., equipped with stirring reinforcement wings) And stirring for 3 minutes to obtain a magenta toner (A1).

  Further, a fine magenta toner (A2) having a particle size of not more than a specified particle size was obtained in the classification step. The obtained fine powder magenta toner (A2) had an average particle size of 5 μm or less.

  Using magenta toner (A1), a color printer “Speedia: N5” (manufactured by Casio Computer Co., Ltd.) was used to perform a printing test, and the recovered magenta toner (A3) was obtained by taking out from TS after the developer life.

(B) Recycled cyan toner With the same material composition and the same process conditions as the above magenta toner, except that the colorant was replaced by 3 parts by mass of ECB-301 (manufactured by Dainichi Seika Kogyo Co., Ltd.) Toner (B1) was obtained.

  Further, a fine cyan toner (B2) having a specified particle size or less was obtained in the classification step. The obtained finely divided cyan toner (B2) had an average particle diameter of 5 μm or less.

  Using cyan toner (B1), a color printer “Speedia: N5” (manufactured by Casio Computer Co., Ltd.) was used to perform a printing test. The cyan toner (B1) was taken out from the TS after the developer life, and recovered cyan toner (B3) was obtained.

(C) Recycled yellow toner A yellow toner (C1) was obtained with the same material composition and the same process conditions as the above magenta toner except that 3 parts by mass of Y74 (manufactured by Sanyo Dye Co., Ltd.) was used.

  In addition, a fine yellow toner (C2) having a specified particle size or less was obtained in the classification step. The average particle diameter of the obtained fine powder yellow toner (C2) was 5 μm or less.

  Using yellow toner (C1), a color printer “Speedia: N5” (manufactured by Casio Computer Co., Ltd.) was used to perform a printing test. The yellow toner (C3) was taken out from TS after the end of the developing device life to obtain recovered yellow toner (C3).

2. (Standard black toner)
100 parts by mass of polyester resin (manufactured by Kao Corporation: Tg: 65 ° C./Tm: 140 ° C.), 4 parts by mass of colorant: Monarch 880 (manufactured by Cabot), release agent: Carnauba wax No. 1 powder as wax 4 parts by mass (manufactured by Hiroyuki Kato) and 1 part by mass of T-77 (manufactured by Hodogaya Chemical Co., Ltd.) as a charge control agent are put into a Henschel mixer (manufactured by Mitsui Mining Co., Ltd., equipped with standard feathers) The mixture was stirred and mixed for 4 minutes at a peripheral speed of 20 m / sec.

  The obtained mixed powder is melt-kneaded with a twin screw extruder, stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Co., Ltd., 2 mm screen). The fine particles were obtained by pulverization and classification so that the average particle diameter of the toner was 9.0 μm.

  2 parts by mass of “RY200” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) as an external additive is added to 100 parts by mass of the obtained fine particles, and Henschel mixer (manufactured by Mitsui Mining Co., Ltd., equipped with stirring reinforcement wings) The mixture was stirred and mixed for 3 minutes to obtain a reference black toner.

  Next, examples and comparative examples using the recycled toner obtained as described above are shown.

  The softening point, glass transition point (Tg), and particle size were measured as follows.

1. Measurement of softening point Apparatus: Flow tester (manufactured by Shimadzu Corporation, CFT-500D)
Sample: 1g
Temperature increase rate: 6 ° C / min Load: 20kg
Nozzle: 1mm diameter, 1mm length
1/2 method: The temperature at which half of the sample flowed out was taken as the softening point.

2. Glass transition point (Tg) measurement apparatus: differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-60)
Sample: 8mg
Temperature raising conditions: The temperature is raised to 160 ° C. at 10 ° C./min, cooled to 35 ° C. at a temperature lowering rate of 10 ° C./min, and then raised again to 160 ° C. at 10 ° C./min.

  At the second temperature increase, the intersection of two tangents of the curve portion obtained by the transition was taken as the glass transition point.

3. Particle size measurement device: Multisizer II (manufactured by Coulter Co., Ltd.)
Sample: A small amount of sample, purified water and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.

  Measurement: The aperture was 100 μm, the count was 50,000, and the volume average particle size was obtained.

Example 1
100 parts by mass of polyester resin (manufactured by Kao Corporation: Tg: 65 ° C./Tm: 140 ° C.), 4 parts by mass of colorant: Monarch 880 (manufactured by Cabot), release agent: Carnauba wax No. 1 powder as wax A toner material consisting of 4 parts by mass (manufactured by Hiroyuki Kato) and 1 part by mass of T-77 (manufactured by Hodogaya Chemical Co., Ltd.) as a charge control agent was used as 100 parts by mass of a black toner material. (Standard Co., Ltd.) and stirred and mixed for 4 minutes at a peripheral speed of 20 m / sec.

  To 100 parts by mass of the black toner material, 10 parts by mass of the fine powder yellow toner (C2) obtained in Production Example 1 is added as a reusable material, and again to the Henschel mixer (Mitsui Mine Co., Ltd., equipped with standard feathers). The mixing conditions were changed, and the mixture was stirred and mixed at a blade peripheral speed of 10 m / sec for 4 minutes.

  The obtained mixed powder is melt-kneaded with a twin screw extruder, stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Co., Ltd., 2 mm screen). The fine particles were obtained by pulverization and classification so that the average particle diameter of the toner was 9.0 μm.

  As an external additive, 2 parts by mass of “RY200” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) is added to 100 parts by mass of the obtained fine particles, and a Henschel mixer (manufactured by Mitsui Mining Co., Ltd., equipped with stirring reinforcement wings) The mixture was stirred and mixed for 3 minutes to obtain a black toner.

Example 2
Example except that 15 parts by mass of fine powder cyan toner (B2) obtained in Production Example 1 was used instead of 10 parts by mass of fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as in Example 1, a black toner was obtained.

Example 3
Example except that 15 parts by mass of the fine powder magenta toner (A2) obtained in Production Example 1 was used in place of 10 parts by mass of the fine powder yellow toner (C2) obtained in Production Example 1 as the reusable material. In the same manner as in Example 1, a black toner was obtained.

Example 4
Example 1 except that 15 parts by mass of fine powder cyan toner (B2) obtained in Production Example 1 was further added to 10 parts by mass of fine yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as above, a black toner was obtained.

Example 5
Example 1 except that 15 parts by mass of the fine powder magenta toner (A2) obtained in Production Example 1 was further added to 10 parts by mass of the fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as above, a black toner was obtained.

Example 6
Instead of 10 parts by mass of the fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material, 15 parts by mass of the fine powder cyan toner (B2) obtained in Production Example 1 and 15 parts by mass of the fine powder magenta toner (A2) A black toner was obtained in the same manner as in Example 1 except that the part was used.

Example 7
Instead of 10 parts by weight of the fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material, 5 parts by weight of the fine powder yellow toner (C2) obtained in Production Example 1 and 5 parts by weight of the fine powder cyan toner (B2) A black toner was obtained in the same manner as in Example 1 except that 5 parts by mass and 5 parts by mass of fine magenta toner (A2) were used.

Example 8
As a reusable material, 10 parts by mass of fine yellow toner (C2) obtained in Production Example 1 and 10 parts by mass of fine cyan toner (B2) and fine magenta toner (A2) obtained in Production Example 1 were used. A black toner was obtained in the same manner as in Example 1 except that.

Example 9
Instead of 10 parts by mass of the fine yellow toner (C2) obtained in Production Example 1 as a reusable material, 10 parts by mass of the recovered yellow toner (C3) obtained in Production Example 1 and 10 parts by mass of the recovered cyan toner (B3); A black toner was obtained in the same manner as in Example 1 except that 10 parts by mass of recovered magenta toner (A3) was used.

Comparative Example 1
A black toner was obtained in the same manner as in Example 1 except that 10 parts by mass of the fine yellow toner (C2) obtained in Production Example 1 was 30 parts by mass.

Comparative Example 2
Example except that 30 parts by mass of fine powder cyan toner (B2) obtained in Production Example 1 was used in place of 10 parts by mass of fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as in Example 1, a black toner was obtained.

Comparative Example 3
Example except that 30 parts by mass of fine powder magenta toner (A2) obtained in Production Example 1 was used in place of 10 parts by mass of fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as in Example 1, a black toner was obtained.

Comparative Example 4
Instead of 10 parts by mass of the fine yellow toner (C2) obtained in Production Example 1 as a reusable material, 15 parts by mass of the fine yellow toner (C2) obtained in Production Example 1 and 15 parts by mass of the fine cyan toner (B2) A black toner was obtained in the same manner as in Example 1 except that 15 parts by mass and fine magenta toner (A2) were added.

Comparative Example 5
As a reusable material, 10 parts by mass of the fine powder yellow toner (C2) obtained in Production Example 1, and further 10 parts by mass of the fine powder cyan toner (B2) obtained in Production Example 1 and 20 parts by mass of the fine powder magenta toner (A2). A black toner was obtained in the same manner as in Example 1 except that.

Comparative Example 6
Instead of 10 parts by weight of the fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material, 20 parts by weight of the fine powder yellow toner (C2) obtained in Production Example 1 and 10 parts by weight of the fine powder cyan toner (B2) A black toner was obtained in the same manner as in Example 1 except that the part was used.

Comparative Example 7
Instead of 10 parts by mass of fine powder yellow toner (C2) obtained in Production Example 1 as a reusable material, 20 parts by mass of fine powder cyan toner (B2) obtained in Production Example 1 and 10 parts by mass of fine powder magenta toner (A2) A black toner was obtained in the same manner as in Example 1 except that the part was used.

Comparative Example 8
Example 1 except that 20 parts by mass of fine powder cyan toner (B2) obtained in Production Example 1 was further added to 10 parts by mass of fine yellow toner (C2) obtained in Production Example 1 as a reusable material. In the same manner as above, a black toner was obtained.

  The black toners obtained in the above examples and comparative examples were evaluated by performing the following tests.

Test 1—Powder Hue One index for determining toner compatibility is a method of measuring the color shift in the powder hue, which can be determined at the toner manufacturing stage.
“Spectroscopic color difference meter: SE2000” (manufactured by Nippon Denshoku Industries Co., Ltd.) is used.
Measure with a measurement area of 30φ with D65 / 2 light source setting.
A 30 mm adapter for powder cells is set on the upper part of the main body. 3.0 g of toner is weighed in a powder cell, tapped 10 times from a height of 5 mm, and placed on an adapter for measurement. The measurement is performed by measuring the distance ΔE between two samples of the color coordinates of L ^* , a ^* , and b ^* , and evaluated according to the following criteria. The reference toner is the black toner produced in Production Example 2.

  A: ΔE = 3 or less: Level that can be used without any problem.

  ○: ΔE = 3 to 5 or less: A level with no problem although there is a slight color difference.

  Δ: ΔE = 5 to 7 or less: Level at which the color difference can be understood.

  X: Greater than 7: The difference in color is clearly understood and it is difficult to use as black.

Test 2 Measured with OPC fog X-RITE 938 (manufactured by X-RITE) (toner density on drum in white paper development).
At N5, the printer is turned off while white paper is being printed, and the toner amount between development and transfer on the drum is peeled off with a mending tape. The mending tape blank and the toner adhering mending tape are measured by X-RITE, and the difference is taken as the value of drum fog (OPC fog) and evaluated according to the following criteria.

◎: 3 or less ○: 3 to 5 or less △: 5 to 7 or less ×: Test larger than 7 3-Fixability (low temperature side)
The fixing unit of the same device as in Test 2 is modified so that the temperature can be varied, and a fixing tester is obtained. After obtaining an unfixed image using the same apparatus as in Test 2, the temperature is varied every 10 ° C. within the fixing temperature range of 130 to 200 ° C. with the fixing tester, and the non-fixed image is fixed. The area is measured to obtain the low-temperature fixing characteristics. The fixing temperature here is the upper set temperature of the two fixing rolls, and the lower fixing roll is set to the upper roll of −20 ° C.

The image pattern was solid printing, and the paper was XEROX P paper A4 size (mass 64 g / m ² ).

(High temperature side)
A4 size paper (Xerox-P paper) is used, and a solid image is printed to determine the fixability. The process speed was 129.3 mm / sec and the fixing temperature was 150 ° C.

(Evaluation criteria)
A: The minimum fixing temperature is less than 140 ° C. There is no offset on the high temperature side.

  ○: The minimum fixing temperature is 140 ° C. or higher and lower than 150 ° C. There is no offset on the high temperature side or a slight practically no problem level.

  X: The minimum fixing temperature is 150 ° C. or higher. Or, the level at which the occurrence of offset is recognized and becomes a problem.

Test 4-Durability A non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer, 29 sheets per minute (A4 side) machine) was mounted with toner in a normal environment (25 ° C. , 50% RH), after continuously printing 10,000 sheets of 5% print images using plain paper (XEROX-P paper A4 size), solid images are printed and image degradation is evaluated. At the same time, remove the doctor blade and observe the fused state on the blade.

(Evaluation criteria)
(Double-circle): Image degradation is not seen and fusion on a doctor blade is not confirmed.

  ○: Image degradation is not observed and there is no practical problem, but fusion is observed on the doctor blade.

  X: Image deterioration is observed and there is a problem in practical use. Fusion occurred on the doctor blade.

The above evaluation results are shown in the following table.

  From the above table, the following is clear. That is, none of the black toners of Examples 1 to 9 manufactured by adding fine powder color toner or recovered color toner of a predetermined amount or less has any color shift, and in any of fog characteristics, fixability and durability. Are better.

  The toners of Examples 1 to 3 use fine color toners for each color, but the yellow color coordinate is the farthest from black among the three colors, so that the addition amount is 10% by mass. ΔE is a high value. Therefore, the amount of fine yellow toner is limited to be lower than that of other colors.

  The toners of Examples 4 to 6 use fine color toners of two colors each, and the total amount thereof is higher than the case of one color at a time, so the color shift ΔE is the result near the allowable upper limit. became. However, there are no problems with respect to fixing characteristics, fogging, and durability.

  The toners of Examples 7 and 8 reused three fine color toners, and the most stable results were obtained when multiple colors were reused. Further, it was confirmed that stable characteristics could be obtained even when the addition amount of each color was increased from 5 parts by mass to 10 parts by mass.

  The toner of Example 9 was obtained by adding 10 parts by mass of the collected color toner for each color instead of the fine color toner, but there was no problem in production even if the collected color toner containing the external additive was reused. However, it was found that it could be handled in the same manner as when the fine color toner was added.

  On the other hand, the toners of Comparative Examples 1 to 3 use fine color toner for each color and the amount added is as large as 30 parts by mass. It was a big result. In particular, the toner of Comparative Example 1 to which fine powder yellow toner is added has a particularly large ΔE compared to other colors, and it is necessary to suppress the reuse amount of the fine powder yellow toner compared to other colors also from this point. Was confirmed.

  In the toner of Comparative Example 4, 15 parts by mass of magenta, cyan, and yellow fine color toners and 45 parts by mass in total were added, respectively. A high temperature offset was observed, and white streaks due to toner blade fusion were also generated in terms of durability. It is thought that the increase in the total amount of addition and the ratio of the reused toner material that passes through the melt-kneading process a plurality of times increased the shearing of the resin, affecting the durability and fixability.

  In the toner of Comparative Example 5, only the fine magenta toner was increased with respect to the other colors, and as a result, the numerical value of color misregistration was high. In addition, since the total amount was 40 parts by mass, some white streaks were recognized in terms of durability, and the evaluation results were inferior in durability.

  In the toners of Comparative Examples 6 to 8, the addition amount of the two fine powder color toners was changed. However, in the case of the toner of Comparative Example 6 in which the ratio of the fine powder yellow toner is large, the color misregistration results were bad. Since the toner has a large proportion of finely powdered cyan toner and no finely powdered yellow toner is added, the result is slightly inferior in terms of color misregistration. In Comparative Example Toner 8, since 10 parts by mass of fine yellow toner was added, a large color shift occurred. Further, in the toners of Comparative Examples 7 and 8, since the amount of fine cyan toner added is large, the fixability evaluation is at a level that causes no problem in practical use, but the fixability is slightly different from the toner of Comparative Example 6. Was recognized.

  From the results of the above Examples and Comparative Examples, in the case of fine powder yellow toner, it is 10 parts by weight or less, in the case of fine powder cyan toner and fine powder magenta toner, the range is 15 parts by weight or less, and the total amount is 30 parts by weight or less. As a result, sufficient performance as a black toner was found.

  In the toner of Example 9, the residual toner of the developing device was used as the collected toner. However, as long as waste toner used in the same process is used, even if multicolor toners are mixed, If the total amount is in the above range, it can be seen that it can be used without any problem.

The figure which shows the manufacturing process of the black toner which concerns on one Embodiment of this invention.

Claims (2)

  A black toner for electrophotography produced by mixing a raw material containing a binder resin and a black colorant, melt kneading, cooling, pulverizing and classifying the raw material, and the raw material is recovered from the magenta toner production process. At least one of fine dust magenta toner, fine dust cyan toner collected from the cyan toner production process, and fine yellow toner collected from the yellow toner production process is added, and the addition amount of the fine magenta toner is 10 The addition amount of the fine powder cyan toner is 15 parts by mass or less, the addition amount of the fine powder yellow toner is 15 parts by mass or less, and the total addition amount is 30% by mass or less. The black toner for electrophotography characterized by this.   A black toner for electrophotography produced by mixing a raw material containing a binder resin and a black colorant, melting and kneading, cooling, pulverizing and classifying the raw material, and the raw material is recovered from the color image forming process. At least one of magenta toner, cyan toner and yellow toner is added, the added amount of the recovered magenta toner is 10 parts by mass or less, and the added amount of the recovered cyan toner is 15 parts by mass or less. An electrophotographic black toner, wherein the toner is added in an amount of 15 parts by mass or less, and the total added amount is 30% by mass or less.

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