JP3058827B2 - Manufacturing method of electrophotographic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner used for electrophotography.

[0002]

2. Description of the Related Art Conventionally, toners used in electrophotography are generally manufactured by a kneading and pulverizing method. The kneading and pulverizing method is a method in which a colorant, a charge control agent and the like are generally mixed with a binder resin typified by a thermoplastic resin and the like, melt-mixed, and then subjected to pulverization and classification. The particle size of the toner produced by this pulverization method is 7 to 15 μm.
In the range. On the other hand, in recent years, a copier or a printer has been required to have high definition and high image quality, and accordingly, a toner having a small particle diameter, specifically, a particle diameter of 7 μm or less has been demanded.

However, according to the above-mentioned kneading and pulverizing method,
It is difficult to produce a small particle size toner with high yield. In general, a kneading stirrer is widely used in kneading, but the charge control agent cannot be dispersed well in the binder resin. This may be because the frequency of contact of the splash with the charge control agent is insufficient or the mechanism of action of the force is not appropriate. Furthermore, in order to obtain a toner excellent in dispersibility of the charge control agent, it is necessary to perform melt-kneading for a long time. However, when the melt-kneading is performed for a long time, even if the dispersibility of the charge control agent is excellent, the thermal characteristics due to the cleavage of the resin molecular chain deteriorate, and the characteristics required by the toner other than the chargeability deteriorate. In addition, there is a problem that the cost of the toner increases. For this reason,
The number average particle diameter of the charge control agent in the toner is generally 1 to
It was about 3 μm.

[0004] Against the background of such a reduction in the particle diameter of the toner, for example, a suspension polymerization method for producing a toner from a polymerizable monomer has been studied. In the suspension polymerization method, a monomer composition (monomer phase) composed of a polymerizable monomer and a colorant such as carbon black is mixed in a water-miscible medium (aqueous phase) containing a suspension stabilizer. Agitation, granulation to the particle size of the toner
(Granulation step), and a polymerizable monomer is polymerized by radicals generated when a previously added polymerization initiator or a newly added polymerization initiator is decomposed by heat to form a polymer (polymerization). Process) to produce toner.

[0005]

However, it is difficult to obtain a toner in which a charge control agent is well dispersed in a binder resin or the like by the above suspension polymerization method. It was about 3 μm. This is because the charge control agent itself has polarity, so the repelling force and suction force act on the polarity of the binder resin itself. Was difficult to get. In particular, the tendency is remarkable in a toner having a small particle diameter, and it has been difficult to obtain a toner excellent in dispersibility of a charge control agent.

A toner having a low dispersibility of a charge control agent in a binder resin has a problem in developing characteristics due to uneven charging between toner particles. For this reason, it has been desired to obtain a toner having a small particle size and having a charge control agent dispersed well in a binder resin or the like. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for producing a toner having a small particle size and in which a charge control agent is well dispersed in a binder resin or the like. .

[0007]

According to the method for producing a toner of the present invention, at least a polymerizable monomer, a charge control agent, and a polymerization initiator are dispersed by using a dispersing machine having a stirring member that freely moves. Is obtained by dispersing the monomer phase in an aqueous phase and polymerizing to obtain a binder resin. Thereafter, at least the binder resin and a colorant are melt-kneaded, pulverized, and classified to obtain a toner. I do.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for producing an electrophotographic toner of the present invention will be described in more detail. The electrophotographic toner according to the present invention is mainly composed of a binder resin, a pigment, and a charge control agent. As a main component of the monomer composition constituting the binder resin for a toner, for example, a polymerizable monomer as described below can be used. Such polymerizable monomers include, for example, styrene and styrene such as α-methylstyrene and derivatives thereof; methacrylic acid,
Examples include polymerizable monomers such as methacrylic acid and its derivatives such as methyl methacrylate and ethyl methacrylate; and acrylic acid and its derivatives such as acrylic acid, methyl acrylate, and 2-ethylhexyl acrylate. These can be used alone or as a mixture depending on the purpose.

In order to improve the offset resistance, waxes such as paraffin wax and low-softening compounds having releasability such as low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene are used as monomers. It may be added to the composition or the binder resin.

Known pigments are used as the colorant.
In particular, for carbon black, the number average particle size, oil absorption,
It can be used without restriction on pH and the like. For example, Mitsubishi Chemical Corporation, # 10B, # 5B, # 40, # 2400B, MA
Pigments commercially available under trade names such as -100. As various chromatic colorants such as blue, red, and yellow, those that can be dispersed or dissolved in the monomer composition and exhibit a color that is clear and has excellent stability over time when used as a toner are used. . Examples of such coloring pigments include phthalocyanine pigments, rhodamine lake pigments, azo lake pigments, and the like. Particularly, for example, a metal-containing pigment such as a copper phthalocyanine-based pigment is also preferable as a pigment because it also serves as a charge control agent described below.

As the charge control agent, generally known ones can be used. For example, a metal complex of a carboxyl group, a sulfonic acid ester, or an organic compound having a nitrogen-containing group, a nigrosine compound, an azine compound, a main chain or a side chain may be used. Polymer compounds having a polar functional group such as sulfonic acid, a sulfonic acid salt, and a quaternary ammonium salt in the chain, and a resin-based charge control agent (for example, FCA-1001-N by Fujikura Kasei) and the like. it can. In particular, as described above, the metal-containing pigment can play both roles of the pigment and the charge control agent, and is therefore preferable as the charge control agent.

In the electrophotographic toner according to the present invention , a charge controlling agent is dispersed so that the number average particle diameter is 0.3 μm or less. If the number average particle diameter is larger than 0.3 μm, charging between the toner particles is not uniform, which causes a problem in developing characteristics, which is not preferable.

In this specification, the “number average particle size” refers to a value under the following measurement conditions. Embedding agent of toner (epoxy resin (manufactured by EM Japan, trade name:
Quetol 812) 10.9 g, dodecenyl succinic anhydride (DDSA) 3.9 g, methyl nadic anhydride (MNA) 7.66 g, and tri (dimethylaminomethyl) phenol (DMP) 0.18 g). Disperse uniformly and heat at 40 ° C. for 1 week to cure. After curing, the toner-embedded epoxy resin is sliced with a microtome (trade name: MF6000, manufactured by Dupont), and is transmitted through an electron microscope (trade name: L, manufactured by Topcon, Inc.).
EM-2000), and the obtained image is analyzed with an image analyzer (manufactured by PIAS, trade name: LA525) to analyze the dispersion state, the number of particles, and the like, thereby obtaining “number average particle diameter”.

Next, a method for producing the electrophotographic toner of the present invention having the above-mentioned excellent charge control agent having a number average particle diameter will be described. The method for producing an electrophotographic toner of the present invention is to obtain a monomer phase by dispersing at least a polymerizable monomer, a charge control agent, and a polymerization initiator using a disperser having a stirring member that freely moves. A production method in which the monomer phase is dispersed in an aqueous phase containing a suspension stabilizer and polymerized to obtain a binder resin. Thereafter, at least the binder resin and a colorant are melt-kneaded, pulverized, and classified to obtain a toner. It is. According to the dispersing machine having the free-moving stirring member, the preferable contact frequency of the stirring member for dispersing the charge controlling agent in the polymerizable monomer and the mechanism of the force can be realized. A binder resin dispersed so that the average particle diameter becomes 0.3 μm or less can be obtained. Accordingly, even in the toner obtained by melt-kneading, pulverizing, and classifying using the binder resin, the charge controlling agent is dispersed so that the number average particle diameter is 0.3 μm or less. The free-moving stirring member corresponds to a glass or ceramic ball,
The ball moves freely in the dispersing machine. Examples of the dispersing machine include a high-efficiency high-speed dispersing machine, and more specifically, a dispersing machine marketed under the trade name of DYNO-MIL by Shinmaru Enterprises, or Oshima Iron Works or A ball mill type disperser commercially available from Makino Iron Works, Ltd. or the like is preferable. DYNO-
The preferable stirring conditions in the MIL vary depending on the characteristics of the toner. To obtain a toner in which the charge control agent is dispersed so that the number average particle diameter is 0.3 μm or less, it is necessary to use 15 times.
The stirring may be performed at 00 rpm to 10,000 rpm for 10 minutes to 1 hour.

The method of dispersing the monomer phase in the aqueous phase and subjecting it to polymerization granulation may be carried out by using a commonly used stirrer, such as HOMOM from Tokushu Kika Kogyo Co., Ltd.
A stirrer marketed under the trade name IXER can be mentioned. The stirring conditions at this time are set according to a desired particle diameter and the like. Generally, in order to obtain a toner having a particle diameter of about 7 μm,
After stirring for about 5 minutes at a polymerization temperature of about 50 ° C. to 90 ° C., the polymerization reaction may be performed while stirring at a low speed for 3 hours to 10 hours. After the reaction is completed, the toner particles are washed, filtered,
By performing drying, a toner in which the charge control agent of the present invention is uniformly dispersed can be obtained.

The above polymerization initiator is preferably soluble in a polymerizable monomer. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvalero) Nitrile), and 2,2′-azobis-4-
Examples thereof include azo or diazo polymerization initiators such as methoxy-2,4-dimethylvaleronitrile; and peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, and isopropyl peroxycarbonate. In addition to using these polymerization initiators alone, water-soluble initiators such as potassium persulfate and ammonium persulfate can be used in combination. The suspension stabilizer is not particularly limited, and a known suspension stabilizer can be used.

[0017]

EXAMPLES Hereinafter, the method for producing the electrophotographic toner of the present invention will be described more specifically based on Examples and Comparative Examples. In the examples and comparative examples, “parts” means “parts by weight”. <Example 1> In a polymerizable monomer composed of 80 parts of styrene and 20 parts of n-butyl acrylate, 2 parts of a charge control agent (trade name: T-4-48, manufactured by Hodogaya Chemical Industry Co., Ltd.) And 5 parts of a polymerization initiator 2, 2'-azobisvaleronitrile, and DY was added.
The charge control agent was dispersed using NO-MIL (dispersion machine manufactured by Shinmaru Enterprises) to prepare a monomer phase of a polymerizable monomer. Next, 3 parts of tribasic calcium phosphate (to the aqueous phase) and 0.05 parts of sodium dodecylbenzenesulfonate (to the aqueous phase) were dispersed in water to prepare 250 parts of an aqueous phase. The phase ratio (weight) of the thus-prepared monomer phase and aqueous phase was adjusted to be 1: 4, put in a beaker, and used at room temperature using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). The mixture was stirred at 10,000 rpm for 1 minute and granulated. After granulation, the mixture was stirred at 80 ° C., 5
The monomer composition was polymerized under the conditions of time. After cooling and filtering the resulting polymer composition (binder resin), dilute nitric acid is used to remove tribasic calcium phosphate on the surface of the polymer particles, washed with water until the washing solution becomes neutral, and dried to obtain a binder resin for toner. I got Next, using this resin, a toner is experimentally produced by a kneading and pulverizing method. After mixing the composition having the following composition, the mixture was hot-melt kneaded with an extruder, cooled, and then pulverized and classified with a jet mill to obtain toner particles having an average particle diameter of 7 μm by a kneading and pulverizing method. -100 parts of binder resin-5 parts of carbon black (Mitsubishi Kasei # 40) (for binder resin)-2 parts of low molecular weight polypropylene resin (for binder resin) (Viscol 550P manufactured by Sanyo Chemical Industries, Ltd.) The dispersion state of the charge control agent in the toner was measured under the conditions described in (1). As a result, the number average particle diameter of the charge control agent in the toner was 0.29 μm.

Comparative Example 1 A polymerizable monomer composed of 80 parts of styrene and 20 parts of n-butyl acrylate was combined with 5 parts of carbon black (trade name: # 40, manufactured by Mitsubishi Kasei Co., Ltd.) and a charge control agent ( Hodogaya Chemical Industry Co., Ltd .: Trade name: T-4-48) 4.0 parts and 2,
5 parts of 2'-azobisvaleronitrile was added, and DYNO was added.
-Partition of carbon black and charge control agent by MILL
The monomer phase was prepared without sparging. Next, 3 parts of tribasic calcium phosphate (for the aqueous phase) and 0.05 parts of sodium dodecylbenzenesulfonate (for the aqueous phase) were dispersed in water to prepare 250 parts of an aqueous phase. The phase ratio (weight) of the monomer phase and the aqueous phase thus prepared was adjusted to be 1: 4, and the mixture was placed in a beaker at room temperature using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). The mixture was stirred at 10,000 rpm for 1 minute and granulated. After the granulation, the monomer composition was polymerized at 80 ° C. for 5 hours while stirring to such an extent that droplets did not precipitate. After cooling and filtering the polymer composition obtained as described above, tribasic calcium phosphate on the surface of the polymer particles was removed with dilute nitric acid, washed with water until the washing solution became neutral, and dried to obtain a polymerized toner. The particle size of the obtained toner is 7 μm, and the dispersion state of the charge control agent is 1.0 μm.
Met.

[0019]

[0020]

The charge distribution of the electrophotographic toners obtained in the examples and comparative examples was measured under the following conditions. Using a non-coated ferrite carrier (manufactured by Dowa Mining Co., Ltd., trade name: DFC-200 (type S)) as a carrier,
D was stirred under the condition of 5% (100 rpm, 30 min), and then measured using q-MATER (charge amount distribution measuring device developed by Epping). The measurement results are shown in Figure 1 and <br/> Figure 2.

As is clear from FIGS. 1 and 2 ,
The toner of Example 1 has a sharp charge distribution shape,
It was confirmed that there was no generation of toner particles of the opposite polarity to the polarity adjusted by the charge control agent. On the other hand, the toner of Comparative Example 1 had a broad charge amount distribution shape, and generation of opposite polarity toner particles was confirmed. Further, the obtained toner was copied by a copying machine, and the image was evaluated by visual inspection. As a result, it was found that a good image could be obtained with less fog on paper and fog on a photoreceptor.

[0023]

According to the method for producing an electrophotographic toner of the present invention, an electrophotographic toner having a uniform charge distribution can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a charge distribution of a toner obtained in Example 1.

FIG. 2 is a distribution of charge of a toner obtained in Comparative Example 1 .
FIG.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Takayuki Hamanaka, Inventor 3-1 Yomoba Tomoecho, Shizuoka City, Shizuoka Pref. JP-A-1-158460 (JP, A) JP-A-1-100562 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] At least a polymerizable monomer, a charge control agent,
And the polymerization initiator is dispersed using a disperser having a stirring member that freely moves to obtain a monomer phase, and then the monomer phase is dispersed in an aqueous phase and polymerized to obtain a binder resin. A method for producing a toner, comprising: melting, kneading, pulverizing, and classifying a resin and a colorant to obtain a toner.