JP2006171017A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of a reversely charged or weakly charged toner, and of fogging and toner flying-off caused by the toner. <P>SOLUTION: In a method for manufacturing toner by externally adding silica, having an average particle diameter of 20-40 nm surface-treated with aminosilane (AS)+hexamethyldisilazane (HMDS) and silica, having an average particle diameter of 6-20 nm surface-treated with HMDS, in the first stage of a multistage treatment, the silica surface-treated with AS+HMDS is added externally, and in the second-stage or later external addition treatment, the silica surface-treated with HMDS is added externally. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a toner production method in which two types of silica are externally added.

There has been proposed a toner that stabilizes toner charging by externally adding positively charged hydrophobic silica fine particles as a charge control agent to negatively charged toner base particles (Patent Document 1).
In addition, by adding at least a positively chargeable hydrophobic silica and a negatively chargeable hydrophobic silica to a toner base used as a specific fluorine-containing polymer fixing aid in order to improve releasability, There has also been proposed a toner that prevents toner aggregation and overcharge in long-term continuous use, which can be seen with a toner blended with a coalescence (Patent Document 2).
Also, the adhesion amount of the hydrophobically charged negatively charged silica and the positively charged silica (average particle diameter of 10 to 50 nm) is controlled within a predetermined range, and a neutral or positively charged part is generated on a part of the toner surface. In addition, there has been proposed a toner having a preferable charging amount by preventing toner fusion by the roller action of this portion and preventing the occurrence of extreme positive charging (Patent Document 3).
In addition, there has been proposed a method in which two types of positively chargeable silica and inorganic fine particles having different sizes are externally added to negatively charged toner base particles to stabilize toner charging (Patent Document 4).
JP 2000-267337 A Japanese Patent Laid-Open No. 2002-14487 JP-A-11-231571 Japanese Patent Laid-Open No. 2002-214834

  In Patent Documents 1 to 4, it is possible to stabilize the chargeability of the toner by adding a positively chargeable external additive, but the chargeability of the toner is not sufficiently controlled, and the charge amount distribution Has a problem that the toner is scattered and fogging occurs due to reverse charging or weakly charged toner.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to suppress the occurrence of reversely charged or weakly charged toner, and the occurrence of fog and toner scattering associated therewith as much as possible.
Therefore, the present invention provides a toner externally added to silica surface-treated with aminosilane (AS) + hexamethyldisilazane (HMDS) having an average particle diameter of 20 to 40 nm and silica surface-treated with HMDS having an average particle diameter of 6 to 20 nm. In the production method, the silica surface-treated with the AS + HMDS is externally added in the first stage of the multi-stage treatment, and then the silica surface-treated with the HMDS is externally added in the second and subsequent external addition processes. And
Further, the present invention is characterized in that the external addition process is performed using a Q-type mixer.

  In the present invention, the positively charged hydrophobic silica is externally added in the first stage of the multistage treatment, and then the negatively charged hydrophobic silica having a particle diameter smaller than that of the positively charged hydrophobic silica is externally added in the second and subsequent stages. Thus, the positively charged hydrophobic silica is selectively attached to the toner surface, and the positively charged hydrophobic silica functions as a microcarrier when the toner is frictionally charged with each other or with a charging member (regulation blade, etc.). By exhibiting this effect, the rising of the charge is accelerated, so that the generation of reversely charged or weakly charged toner can be suppressed as much as possible, and the occurrence of fog and toner scattering can be suppressed.

Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, positively-charged silica having an average particle diameter of 20 to 40 nm, which has been made positively charged by AS treatment and made hydrophobic by HMDS treatment, is externally added in the first stage of the multistage treatment, and HMDS is used in the second and subsequent stages. The main point is that the surface-treated silica having an average particle diameter of 6 to 20 nm is externally added. In the first stage of the multi-stage treatment, positively-charged silica is externally added, so that the positively-charged hydrophobic silica functions as a microcarrier when friction charging between toners or charging members (regulator blades, etc.) is performed. By exhibiting the above, the rise of charging is accelerated, so that the generation of reversely charged or weakly charged toner is suppressed as much as possible.

  Note that a Q-type mixer is used as a mixer for external addition treatment, and the laminar flow in the tank is positively used to increase the distance that the toner base particles and the external additive roll, thereby making it selective. Since it is possible to cause adhesion, it is preferable to use a Q-type mixer.

An example of a Q-type mixer is shown in FIG.
The processing tank 210 has a spherical shape having a relatively large horizontal disk-shaped tank bottom 21 and includes a flange 218 at the center so that the processing tank 210 can be divided into two vertically. In addition, the entire spherical portion is provided with a jacket 219 and has a double structure. By flowing a heat medium therethrough, the object to be processed can be heated or cooled. An input port 216 for supplying an object to be processed is provided in the upper part of the processing tank 210, and an exhaust port 217 for discharging a product is provided in the lower part. A drive shaft 215 passes through the center of the disk-shaped tank bottom 211 and can be rotated by external power. A relatively large conical boss 212 having a rounded tip is attached to the drive shaft 215, and a stirring blade 213 is provided on the outer periphery of the lower end of the boss 212. The stirring blade 213 has a slope opposite to the slope of the outer periphery of the boss 212, and the lower edge thereof is an arc along the spherical inner wall of the processing tank 210. An auxiliary blade 214 having a diameter slightly smaller than that of the stirring blade 213 is provided above the boss 212. In this spherical processing tank, the object to be processed rises smoothly along the spherical tank wall by the stirring blades and reaches the vicinity of the top, and the object to be processed dropped from the top of the tank along the surface of the boss. It falls and reaches the stirring blade on the outer periphery of the lower end of the boss, and smoothly flows along the surface of the boss. And the to-be-processed object which fell along the surface of the boss | hub, and reached | attained the stirring blade is discharged | emitted by the rotational force of a stirring blade, raises along a tank wall, and circulates in the inside of a processing tank.

Next, examples and comparative examples will be described.
In addition, the outline | summary of each external additive used below is shown below.
[Positively charged external additive]
NA50H: Silica manufactured by Nippon Aerosil Co., Ltd. (particle size 30 nm)
TG820F: Cabot silica (particle size 8nm)
[Other external additives]
RX200: Silica manufactured by Nippon Aerosil Co., Ltd. (particle size: 12 nm)
TG-811F: Silica manufactured by Cabot (particle size: 8 nm)
RX50: Nippon Aerosil Co., Ltd. silica (particle size 40 nm)
STT-30S: titanium oxide manufactured by Titanium Industry Co., Ltd. (particle size 20 nm)
ST-110S: Titanium Kogyo Co., Ltd. titanium oxide (particle size 80-150 nm)
〔Example〕
Examples 1 to 5 are shown in Table 1.

In Table 1, the reverse charge amount and fog OD value of the toner are evaluated as follows.
The toner of Examples 1 to 5 is set in a LP-9000C magenta developing device manufactured by Seiko-Epson, and the developing bias condition is set so that the solid OD value is about 1.2. When the reverse charge amount exceeds 50 [fC], it is determined that “there is a large amount of reverse charge toner”.
Further, the fog OD value on the OPC at that time is measured by a tape transfer method. With the tape transfer method, a mending tape manufactured by Sumitomo 3M is applied, the fog toner is transferred onto the tape, and then applied onto a blank paper, and the density is measured with a reflection densitometer. When the fog OD value obtained by subtracting the density exceeds 0.02, it is determined that “there is much fog”.

As can be seen from Table 1, fogging is suppressed in any of Examples 1 to 5 by externally adding a positively chargeable external additive in the first stage of the multistage treatment.
[Comparative Example]
Comparative Examples 1 and 2 are shown in Table 2.

  In Comparative Example 1, when a positively chargeable external additive and another external additive are simultaneously charged in the first stage of the multi-stage treatment, Comparative Example 2 reverses the order of external addition and puts the other external additive in one stage. In the case where the positively chargeable external additive was externally added to the second stage, the reverse charge amount and fog OD value were evaluated in the same manner as in the examples. Thus, the reverse charging toner (fogging) could not be suppressed.

  According to the present invention, the generation of reversely charged or weakly charged toner can be suppressed as much as possible, and the occurrence of fogging and toner scattering can be suppressed.

It is a figure explaining the example of Q type mixer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 200 ... Mixing processing tank, 201 ... Lower blade, 202 ... Upper blade, 210 ... Processing tank, 212 ... Boss, 213 ... Stirring blade, 214 ... Auxiliary blade, 215 ... Drive shaft, 216 ... Input port, 217 ... Discharge port.

Claims (2)

In a method for producing a toner in which silica surface-treated with aminosilane (AS) + hexamethyldisilazane (HMDS) having an average particle diameter of 20 to 40 nm and silica surface-treated with HMDS having an average particle diameter of 6 to 20 nm are externally added. A method for producing a toner, wherein the silica surface-treated with AS + HMDS is externally added to the first stage of the treatment, and then the silica surface-treated with HMDS is externally added in the second and subsequent stages of external addition treatment. . The toner manufacturing method according to claim 1, wherein the external addition process is performed using a Q-type mixer.

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