JPH0772655A - Production of electrophotographic toner - Google Patents

Abstract

PURPOSE:To lessen the generation of smells by bringing toner particles produced by a specific plasma atmosphere into contact with this plasma atmosphere, thereby executing the surface treatment thereof. CONSTITUTION:At least one kind of gases selected from argon, helium, air, oxygen, nitrogen, hydrogen, carbon monoxide, nitrogen monoxide, ammonia and tetrafluoromethane are converted to plasma under conditions of a high-frequency electric power of 10 to 100W and the toner particles produced by a kneading and pulverizing method or polymerizing method are brought into contact with this plasma atmosphere for 10 seconds to 120 minutes, by which the surface treatment of the toner particles is executed. The plasma treatment in such a case is different from the plasma polymn. forming org. polymer thin films by using an org. gas. The plasma treatment is executed by applying devices having various kinds of mixed mechanisms of, for example, a bell-jar type internal electrode system, a cylindrical or fluidized bed type external electrode system.

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 an electrophotographic toner for developing an electrostatic charge image formed by electrophotography, electrostatic printing, electrostatic recording or the like.

[0002]

2. Description of the Related Art Conventional toner for electrophotography is styrene-
Kneading in which a binder resin such as an acrylic ester copolymer system or a styrene-butadiene copolymer system or a polyester system, a colorant such as carbon black or a dye, and a charge control agent are blended, melt-kneaded, and then pulverized and classified. Fine particles having an average particle size of 5 to 20 μm, which are produced by a pulverizing method or a suspension or emulsion polymerization method are used. The electrophotographic toner thus produced has an appropriate specific charge due to frictional charging with the carrier and adheres to the surface of the carrier by the force of static electricity to form a developer. In the development process using such a developer, an electrostatic latent image is formed on the photoconductor by utilizing a photoconductive phenomenon, and the charged electrophotographic toner in the developer is electrostatically charged by a magnetic brush of a carrier. This is the process of making a visible image by attaching it to a latent image. Then, after the toner image on the surface of the photoconductor is transferred to the copy paper in the transfer process, the binder resin in the electrophotographic toner is melted and fused to the copy paper in the fixing process to form an image. There are three fixing methods: oven, heat roller, and pressure. Except for the pressure method, the former two methods both use heat. When applied to the fixing method using such heat, the binder resin of the electrophotographic toner is melted by the conductive heat transfer or the radiant heat transfer, the binder resin is hard to be included in the copy paper, and is fixed by the anchor effect.

[0003]

In the case of the fixing method using heat as described above, heat is applied from the surface of the toner particles to the inside by, for example, a heat roller, so that the inside of the binder resin in the toner particles is heated. The remaining monomers evaporate and generate gas. This gas leaked out of the copying machine, causing a problem of generation of odor. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a method for producing an electrophotographic toner that reduces the generation of odor.

[0004]

Means for Solving the Problems The present invention has been made as a result of intensive studies for achieving the above-mentioned object, and its outline is as follows: argon, helium, air, oxygen, nitrogen, hydrogen,
At least one gas selected from carbon monoxide, nitric oxide, ammonia, and tetrafluoromethane has high-frequency power of 1
An electron characterized in that plasma is formed under the condition of 0 W to 100 W, and the toner particles produced by the kneading pulverization method or the polymerization method are brought into contact with the plasma atmosphere for 10 seconds to 120 minutes to perform surface treatment of the toner particles. This is a method for producing a photographic toner.

The present invention has found that the use of the toner particles thus modified by the plasma treatment significantly reduces the odor. The plasma treatment in the present invention is different from plasma polymerization in which an organic polymer thin film is formed using an organic gas. Hereinafter, the present invention will be described in detail. As an apparatus used for plasma treatment, for example, a bell jar type of internal electrode type, a cylindrical type of external electrode type,
It can be performed by applying an apparatus having various mixing mechanisms such as a fluidized bed type. Hereinafter, description will be given with reference to the drawings.
FIG. 1 is an example of a bell jar type plasma processing apparatus and shows a parallel plate electrode type plasma apparatus. That is, the inside of the bell jar 11 is a sealed space, and the vibrating plate 13 is placed on the lower electrode plate of the two parallel plate electrodes 12 arranged in parallel with each other, and the toner particles are placed on the vibrating plate 13 to cause the bell jar 11 to be After being evacuated by the vacuum pump 15, a proper amount of gas is flown into the bell jar 11 from the gas introduction part 14, and vibration is transmitted to the toner particles by the vibrating plate 13. By this vibrating operation, the toner particles in the vibrating tray 13 start to fluidize. Next, 10 W to 10 W is applied to the upper and lower parallel plate electrodes 12.
By supplying high-frequency power of 0 W, plasma is generated and the toner particles are surface-treated in the bell jar 11. At this time, since the toner powder is constantly fluidized by vibration and is rolling, the reforming is uniformly performed on the surface of the toner particles, and the surface treatment of plasma is performed uniformly.

The gas flowing from the gas introducing section 14 is at least one kind of gas selected from argon, helium, air, oxygen, nitrogen, hydrogen, carbon monoxide, nitric oxide, ammonia and tetrafluoromethane. Must be
With other gases, the odor improving effect of the present invention cannot be obtained. In addition, high-frequency power of 10 W to 1 is used for plasmaization.
00W (however, when the frequency is 13.56 MHz), the processing time must be 10 seconds to 120 minutes. If the high frequency power is less than 10W, plasma is less likely to be generated,
If it is larger than W, the triboelectrification property deteriorates, and the processing time is 10
If it is less than seconds, the effect of improving odor cannot be obtained, and if it is more than 120 minutes, the surface of the toner particles is melted and the triboelectric charging property is deteriorated. The surface modification rate of the toner particles includes the degree of vacuum, applied voltage, distance between electrodes, substrate temperature, gas type,
Since the plasma operating conditions such as the flow rate and the gas flow pattern in the apparatus change, it is necessary to appropriately find the optimum conditions within the processing conditions according to the various gases.

The toner particles obtained by the kneading and pulverizing method referred to in the present invention are obtained by mixing a binder resin, a colorant, a charge control agent and, if necessary, other additives in a desired composition and then extruding with a single screw. Machine, twin-screw kneading extruder (two-screw extruder) or Ban knea mixer and other melt-kneader, then melt kneading, then crushed by impact crusher such as jet mill, and average particles classified by airflow classifier, etc. Diameter 5-2
It refers to fine particles of 0 μm. Further, the toner particles produced by a polymerization method include a suspension polymerization method or an emulsion polymerization method in which a colorant, a charge control agent and, if necessary, other additives are added to a polymerizable monomer component for a binder resin. It refers to fine particles having an average particle diameter of 5 to 20 μm, which are polymerized by the method described above. As the binder resin referred to in the kneading and pulverizing method and the polymerization method, styrene resin, polyacrylic ester resin, styrene-acrylic ester copolymer resin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, epoxy resin, Examples include polyester resins. Examples of colorants include carbon black, monoazo red pigments, disazo yellow pigments, quinacridone magenta pigments, anthraquinone dyes, and the like, and charge control agents include nigrosine dyes, quaternary ammonium salts, and monoazo metal. Complex salt dyes and the like can be mentioned. Other additives that are added as necessary include polyolefins such as polyethylene and polypropylene as release agents, and fluidizing agents such as hydrophobic silica and colloidal silica.

[0008]

In the electrophotographic toner according to the present invention, the surface of the toner particles is modified by the surface treatment of plasma. That is, it is presumed that the residual monomer is degassed, the surface is cross-linked, the surface functional group is introduced, the surface is decomposed and etched, and the amount of odor generated during fixing is significantly reduced.

[0009]

EXAMPLES The present invention will now be described with reference to examples. Example 1 Toner particles were prepared in the following blending ratio. However, parts indicate weight ratios. The above blends were mixed, melt-kneaded with a twin-screw extruder, pulverized with a jet mill, and classified with an airflow classifier to prepare toner particles having an average particle diameter of 11 μm. The toner particles are placed on a vibrating plate in the plasma processing apparatus of FIG.
g, evacuate to 1 × 10 ^-4 Torr with a vacuum pump,
The particles were shaken and stirred for 10 minutes. After that, argon gas was introduced at a flow rate of 20 cc / min, the degree of vacuum in the processing apparatus was maintained at 0.1 Torr, and a high frequency power source (13.56) was used.
The toner particles are surface-treated for 5 minutes to produce an electrophotographic toner according to the present invention.

Example 2 Example 1 except that the plasma treatment time was changed to 15 minutes.
Surface treatment was carried out in the same manner as in 1. to prepare an electrophotographic toner according to the present invention.

Example 3 Example 1 was repeated except that the plasma treatment time was changed to 60 minutes.
Surface treatment was carried out in the same manner as in 1. to prepare an electrophotographic toner according to the present invention.

Example 4 An electrophotographic toner according to the present invention was prepared by performing surface treatment in the same manner as in Example 1 except that the plasma treatment time was 15 minutes and the gas was changed to nitrogen gas.

Example 5 An electrophotographic toner according to the present invention was prepared by surface-treating in the same manner as in Example 1 except that the plasma treatment time was 15 minutes and the gas was changed to oxygen gas.

Example 6 Stearyl peroxide (20 g) was dissolved in a mixed solution of styrene (800 g) and n-butyl acrylate (200 g).
Carbon black (trade name: # 4 manufactured by Mitsubishi Kasei Co., Ltd.)
0) 120 g and 30 g of nigrosine dye (trade name: Bontron N04 manufactured by Orient Chemical Industry Co., Ltd.) were added and stirred. This mixture is stirred at 40 ° C. for 4 hours with further stirring.
Heated for hours. 25 g of 2,2′-azobisisobutyronitrile was mixed and dissolved in the obtained slurry. An aqueous solution of polyacrylic acid (Wako Pure Chemical Industries, Ltd., about 25%, 80%
80 g (00 to 12000 cp, 25 ° C.) and 45 g of sodium sulfate were dissolved in 5000 g of distilled water, and the solution was added to a stirring machine (Homomixer M type) for 10000 r.
The mixture was stirred at pm for 20 minutes to obtain a dispersion liquid containing a polymerizable monomer and a colorant. This dispersion was added to a 5 liter separable flask container equipped with a reflux tube. After purging the inside of the reaction vessel with nitrogen for 30 minutes, while heating to 95 ° C., a stirrer having a turbine type stirring blade with a diameter of 50 mm is used to
Stirred at rpm for 9 hours. After that, while maintaining stirring,
The inner solution was cooled to room temperature, the polymer particles were filtered off, washed well with water and then dried to obtain an average particle size of 6.2 by the polymerization method.
μm toner particles were obtained. Next, the toner particles are treated as in Example 1.
Plasma surface treatment was performed in the same manner as in 1. to produce an electrophotographic toner according to the present invention.

Comparative Example 1 A comparative electrophotographic toner was prepared in the same manner as in Example 1 except that gas was not added.

Comparative Example 2 The toner particles obtained in Example 1 which were not subjected to plasma treatment were directly used as a comparative electrophotographic toner.

Comparative Example 3 The toner particles obtained in Example 6 which were not subjected to the plasma treatment were directly used as a comparative electrophotographic toner.

Using the electrophotographic toners obtained in the above Examples 1 to 6 and Comparative Examples 1 to 3, the odor property was evaluated in the following manner. Measurement by Gas Chromatograph Mass Spectrometer (GC-MS) Styrene and toluene, which are considered to have a large amount of residual monomers in this measurement, were selected as the components of interest. The measurement condition is a sample amount of 2 mg, and the heating condition is two ways of 120 ° C. and 170 ° C. for 10 minutes. As shown in Table 1, the results are shown in Examples 1 to 1 by the surface modification of the plasma treatment of the manufacturing method of the present invention.
It was confirmed that the amount of residual monomers of styrene and toluene in the electrophotographic toner of No. 6 was small. Further, from the numerical values of Comparative Example 1, it was confirmed that the amount of residual monomer was not reduced only by plasma surface treatment using only vacuum.

Odor sensory test 20g sample in a polystyrene bottle with a capacity of 150cc
After putting it in and closing the cap, it was placed in an oven at a temperature of 50 ° C. After keeping the condition for 8 hours, the container was taken out from the oven, and immediately after that, the cap was opened and the odor was evaluated by the sense of smell. Further, after closing the cap and leaving it at room temperature for 24 hours, the cap was opened and the odor of the same sample was evaluated by the sense of smell. The evaluation was carried out with a rank of 5 levels. In addition, in order to eliminate individual differences, a sensory test was conducted by three people, and the evaluation value was determined by a consultation of the three people. The evaluation criteria show that 5 is odorless, and the more it is 1, the more odor. The above results are shown in Table 1.

[0020]

[Table 1]

As shown in Table 1, it was confirmed that in the case of the electrophotographic toners of Examples 1 to 6 produced by the production method of the present invention, the odor was sufficiently improved and the effect of the plasma surface treatment was sufficient. A four-component developer was prepared by mixing 4 parts of each electrophotographic toner obtained above with 96 parts of a ferrite carrier (trade name: FL-1020 manufactured by Powdertech Co., Ltd.) not coated with a resin. Then, a commercially available copying machine (trade name: S manufactured by Sharp Corporation) using the developer is used.
As a result of conducting a continuous copy test up to 5000 sheets with F-9800), in all of Examples 1 to 6, the triboelectric charge amount was -21 μm / from the initial to 5000 sheets.
It was confirmed that there was no problem in practical use since the image density was changed from g to -24 μm / g and the image density was changed from 1.33 to 1.37 from the initial stage to 5,000 sheets.
The copied original is A4 with a black portion of 10%, the triboelectrification amount is measured by a blow-off triboelectrification amount measuring device manufactured by Toshiba Chemical Co., and the image density is a reflection densitometer RD-914 manufactured by Macbeth. It was used.

[0022]

INDUSTRIAL APPLICABILITY The present invention provides a method for producing an excellent electrophotographic toner in which the monomer remaining in the toner particles can be reduced by plasma-treating the toner particles with a specific gas, and an excellent electrophotographic toner having an improved odor problem can be provided. is there.

[Brief description of drawings]

FIG. 1 is a schematic view of a bell jar type plasma processing apparatus used in the present invention.

[Explanation of symbols]

 11 bell jar 12 parallel plate electrode 13 vibrating plate 14 gas introduction part 15 vacuum pump

Claims (1)

[Claims] 1. At least one kind of gas selected from argon, helium, air, oxygen, nitrogen, hydrogen, carbon monoxide, nitric oxide, ammonia, and tetrafluoromethane under the condition that the high frequency power is 10 W to 100 W. To turn it into plasma,
A method for producing an electrophotographic toner, which comprises contacting toner particles produced by a kneading pulverization method or a polymerization method with the plasma atmosphere for 10 seconds to 120 minutes to perform surface treatment of the toner particles.