JP3462552B2 - Powder surface modification method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing toner and carrier for electrostatic development formed in electrophotography, electrostatic printing, electrostatic recording, etc., magnetic powder, semiconductor powder. Body, fluorescent powder, battery powder and other electronics fields, chromatographic fillers and catalysts, chemical fields, dispersion stabilizers, powder coatings, high-performance coating inks and other coating fields, oxidation resistance Metal fields aiming to improve stability,
The present invention relates to the modification and surface treatment of powders used in the powder industry, which has a wide range of industrial fields such as cosmetics, pharmaceuticals, clinical tests / diagnosis, food fields, and carbon black.

[0002]

2. Description of the Related Art Conventionally, a method of plasma polymerization / treatment is one of the methods for modifying the surface of powder, for example, Japanese Patent Application No. 4-31.
No. 5505. The outline of this method is a surface modification method of plasma polymerization / treatment using a reduced pressure fluidized bed, in which the powder in the reduced pressure fluidized bed is retained in space by the force of gas flow from the lower part to the upper part, that is, buoyancy. After fluidizing, the powder is exposed to a plasma atmosphere to subject the surface of the powder to plasma polymerization / treatment, which is a method of modifying the powder without applying vibration to the reduced pressure fluidized bed body.

[0003]

However, when the above-mentioned conventional reforming method is applied to a general powder reforming treatment, there are the following problems. That is, 10 μm
When a plasma-polymerized film is formed on the surface of the powders below, the fluidization of the powders by the buoyancy of the gas stream does not unravel the powders, and some of the powders do not disperse. A gas flow path called channeling is formed in the block of the powder by blocking, and the gas cannot come into contact with all the powders, resulting in a uniform film on the surface of each powder. There is a problem that a plasma-polymerized film having a thickness cannot be produced. The present invention improves the method of modifying the surface of a powder using a reduced pressure fluidized bed as described above, and a plasma polymerized film is formed on the surface of a powder composed of fine powder having a size of 10 μm or less, which has strong adhesiveness and easily causes channeling. It is an object of the present invention to provide a reforming method for uniformly producing the above or performing the plasma treatment uniformly.

[0004]

The first invention of the present invention is as follows:
A method for modifying a powder surface, which comprises exposing a powder suspended in a polymerizable monomer gas to a plasma atmosphere under vibration to form a plasma-polymerized film of the polymerizable monomer gas on the surface of the powder. Is. A second aspect of the present invention is characterized in that the powder suspended in a non-polymerizable gas is exposed to a plasma atmosphere under vibration, and the surface of the powder is plasma-treated. This is a reforming method. In the present invention, by applying vibration to the powder, it is possible to obtain a stable and good surface condition even in the case of powder having a particle size range of 10 μm or less, which is difficult to modify the surface. It is possible to obtain a good powder surface condition with a smaller amount of gas than in the powder surface modification method using the reduced pressure fluidized bed.

The powder used in the first invention of the present invention includes developing toner and carrier having an average particle diameter of 0.5 μm to 10 μm, magnetic materials such as ferrite and magnetite, various pigment powders, carbonization. Heat-resistant powders such as silicon and silicon nitride, granular and acicular powders such as cosmetics, and short fiber powders such as plastic fibers, cellulose fiber fibers, glass fibers and metal fibers are applied. Further, as the powder used in the second invention of the present invention, one in which at least a part of the polymer material is exposed on the surface of the powder is applied, and for example, the above-mentioned developing toner, resin-coated carrier In addition to plastic fiber, cellulose fiber, glass fiber, metal fiber, various resin powders are applied. In addition, in order to efficiently transmit vibration to the powder, promote fluidization, and obtain a good powder surface state, a powder (about 50 μm to 5 mm) as a medium other than the powder for the purpose of surface modification May be mixed with the powder for processing.

The plasma polymerization and the second plasma treatment referred to in the first aspect of the present invention utilize low temperature plasma, which is also called glow discharge, which is a discharge phenomenon in a gas at a low pressure of usually several Torr or less. According to the surface modification according to the first invention utilizing plasma polymerization, the polymerizable monomer gas is made to be an organic compound, the property of the powder material itself is not changed, and the original powder material does not exist on the surface of the powder. An organic polymer thin film having new physical and chemical properties can be produced. Taking advantage of this feature, it is possible to produce not only a polymerized film of a single polymerizable monomer but also one in which the functional level of the powder surface is controlled by using a plurality of polymerizable monomer gases. For example, in the electrophotographic copying machine developer, when the technique of the present invention is used for surface modification of high-definition fine toner, the surface properties are well balanced in correspondence with low-temperature fixing toner and odor countermeasure toner. Various toners can be manufactured.

Examples of the polymerizable monomer gas used in the present invention include tetrafluoroethylene, hexafluorobenzene, perfluorobenzene, pentafluorobenzene, perfluoropyridine, perfluoromethylcyclohexane, hexafluoropropene, hexamethyldisiloxane and trifluoroethylene. Ethoxyvinylsilane, vinylmethoxysilane, 1,1,3,3-tetramethyldisiloxane,
Tetraethylorthosilicate, diallyldimethylsilane, methane, ethane, propane, n-butane, i-butane, propylene, acrylonitrile, propionitrile, propylamine, arylamine, ethylene, arene, acetylene, ethylene oxide, benzene, toluene, xylene, Examples thereof include, but are not limited to, hexane, cyclohexane, acrylic acid and acrylic acid ester, methacrylic acid and methacrylic acid ester, chlorobenzene, nitrotoluene, styrene, and styrene derivative. When an entrained gas is to be used when supplying the polymerizable monomer gas, an inert gas such as helium, argon, neon or nitrogen can be used as the entrained gas. Further, the plasma treatment according to the second invention is performed by helium, argon, neon, air, oxygen, nitrogen, hydrogen, tetrafluoromethane, carbon monoxide,
A non-polymerizable gas containing at least one gas such as ammonia is made into plasma, and the powder is exposed to this plasma atmosphere for surface treatment modification. Introducing functional groups, surface bridging, branching, oxidation, etc., surface generation such as radical generation, surface decomposition and etching occurs, so in the case of developing toner, for example, the polarity and amount of triboelectrification can be changed arbitrarily. It is possible to improve the storage stability of the toner and prevent the generation of odor during fixing.

Next, an apparatus to which the reforming method of the present invention can be applied will be described. As an apparatus used for the plasma polymerization of the first invention and the plasma treatment of the second invention, various mixing apparatuses such as a bell jar type of internal electrode type, a cross type, and a cylindrical type of external electrode type are applied. However, the latter plasma apparatus using a reduced pressure fluidized bed of the cylindrical external electrode system is particularly preferable, and a vibrating table equipped with a vibration motor having the reduced pressure fluidized bed fixed thereto is preferable. Figure 1
3 is an explanatory view of an example of an apparatus to which the reforming method of the present invention can be applied, in which the electrode 8 connected to an external high-frequency power source 9 is provided below the vacuum decompression fluidized bed 5 made of glass, which is installed and fixed on the vibrating table 10.
And a porous dispersion plate 7 made of a glass bead sintered body (the dispersion plate 7 has a plurality of holes having a diameter of 1 to 20 μm) is provided in the lower part thereof. Further, a manometer 4 for measuring the pressure difference between the upper and lower sides of the reduced pressure fluidized bed 5 and a Pirani vacuum gauge 6 for measuring the pressure inside the reduced pressure fluidized bed 5 are attached, and the gas that has passed through the reduced pressure fluidized bed 5 is recovered as fine powder. Flask 3
It is spouted into the inside and connected to the vacuum pump 1 to reduce the pressure. There are 2 valves for each part.
It shows with. The vibrating table 10 has two vibrating motors 11 arranged at an angle of 45 ° on the bottom, and the vibrating motors 11 cause the depressurized fluidized bed 5 to have a frequency of 10 to 2000 Hz.
And vibration with an amplitude of 0.1 to 2 mm gives an appropriate space to the powder to promote the flow of the powder in the plasma atmosphere, the reforming progresses evenly on the powder surface, and the plasma polymerization / treatment is uniform. Done As described above, the vibrating table 10 applies a vibration to the entire reduced pressure fluidized bed 5 to promote efficient fluidization of the powder. In addition, at the two places on the upper part of the dispersion plate 7,
The electrode 8 is wrapped around the outside of the glass plate,
One is connected to the high-frequency power source 9 via the matching box and the other is connected to the ground so that plasma is generated in the reduced pressure fluidized bed 5. When performing plasma polymerization or plasma treatment, an appropriate amount of the powder to be modified is placed on the porous dispersion plate 7, and the powder is suspended while supplying the polymerizable monomer gas or the non-polymerizable gas. To create a plasma atmosphere.

In order to carry out the first invention of the present invention,
A polymerizable monomer gas is supplied to form a plasma polymerized film on the surface of the powder. That is, the polymerizable monomer gas cylinder 1
The polymerizable monomer gas from No. 5 is supplied to the reduced pressure fluidized bed 5 vibrated by the vibrating table 10 through the flow meter 13 to suspend the powder, and then plasma is generated to form a polymerized film on the surface of the powder. However, as the polymerizable monomer gas,
When volatile liquid monomer such as styrene is used, the liquid monomer is put in the liquid monomer container 12, and the liquid monomer is passed from the non-polymerizable gas cylinder 14 into the liquid monomer container through the flow meter 13 ( After being vaporized together with the (non-polymerizable gas) and supplied into the reduced pressure fluidized bed 5 to suspend the powder, plasma is generated to generate a polymerized film on the surface of the powder. On the other hand, in order to carry out the second aspect of the present invention, the powder surface is plasma-treated using only the non-polymerizable gas. That is, after the non-polymerizable gas is supplied from the non-polymerizable gas cylinder 14 through the flow meter 13 into the vibrating reduced pressure fluidized bed 5 to suspend the powder,
Plasma is generated and the powder surface is plasma-treated to modify the powder surface. In the above, when performing the plasma polymerization using the polymerizable monomer gas, the non-polymerizable gas from the non-polymerizable gas cylinder 14 is directly flown together with the polymerizable monomer gas without passing through the liquid monomer container 12 under reduced pressure fluidized bed. Can also be supplied to. As a result, the polymerization reaction can be suppressed, and an air flow for imparting buoyancy to the powder can be secured. Further, although only one polymerizable monomer gas cylinder 15 is shown in FIG. 1, a plurality of different kinds of polymerizable monomer gas cylinders are prepared to produce a plasma polymerized film having different kinds of polymers at a desired ratio. You can also let it. Also, the reduced pressure fluidized bed 5
A gas other than the polymerizable monomer gas or the non-polymerizable gas may be supplied to suspend the powder, and then the polymerizable monomer gas or the non-polymerizable gas may be supplied. In the present invention, the degree of formation of the polymerized film and the degree of modification of the powder surface include the degree of vacuum, the applied voltage, the distance between the electrodes, the substrate temperature, the type of gas, the flow rate and the flow pattern in the apparatus. It is necessary to find the optimum plasma condition in a timely manner according to various powders, because it depends on the plasma operation condition. When the volume average particle diameter of the powder is 0.5 to 10 μm,
A surface state in which the powder has a true density of 0.9 to 22 kg / cm ³ and the floating state of the powder in the reduced pressure fluidized bed 5 has a porosity of 0.45 to 0.85 is preferable. To obtain

[0010]

EXAMPLES The present invention will now be described with reference to examples. Example 1 In the apparatus shown in FIG. 1, the reduced pressure fluidized bed was made of Pyrex glass and had a height of 1000 mm and an inner diameter of 30 mm, and a vibrating table (VUA-10 manufactured by Chuo Kakoki Co., Ltd.) was fixed to the reduced pressure fluidized bed. The following plasma polymerization was carried out using the above apparatus. Inside the reduced-pressure fluidized bed, a dispersion plate having a large number of holes with a diameter of 3 μm was provided, and an electrode made of a copper plate was wrapped around the cylindrical portion of the reduced-pressure fluidized bed just above the dispersion plate and 100 mm above it. The electrode of is connected to a high frequency power source of 13.56 MHz via a matching box, and the other electrode is connected to the ground. In plasma polymerization, 10 g of toner powder having an average particle size of 6 μm is first placed on a dispersion plate in a reduced pressure fluidized bed, a vibration motor inside a vibrating table is operated to vibrate the reduced pressure fluidized bed, and then a polymerizable monomer gas is added. Hexamethyldisiloxane is supplied as 30 cc / min and argon gas as entrainment gas is supplied as 90 cc / min into the depressurized fluidized bed, and the in-layer pressure is adjusted to 0.1 Torr to suspend the toner powder. A power of 50 W was applied to the inside of the vacuum fluidized bed to form a plasma atmosphere, and the toner powder was exposed to the plasma atmosphere for 10 minutes. Hexamethyldisiloxane was plasma-polymerized on the surface of the toner powder to form a polymer film. The vibration of the reduced pressure fluidized bed was measured by a vibrometer attached to the outside of the reduced pressure fluidized bed.
The z and the amplitude were 1.0 mm, and the average porosity when vibrating was 0.75. The toner powder used is manufactured as follows.・ Styrene-butyl acrylate copolymer resin 100 parts by weight ・ Carbon black 7 parts by weight (Mitsubishi Chemical Co., Ltd., trade name: MA-100) ・ Polypropylene 4 parts by weight (Mitsubishi Kasei Co., Ltd., trade name: Viscole 660P) 2 parts by weight of metal-containing dye (Hodogaya Chemical Co., Ltd., trade name: T-77) In this example, the compound having the above composition was treated by a kneading pulverization method to obtain a toner powder having an average particle size of 6 μm. It was made.
Then silica fine powder (product name: R, manufactured by Nippon Aerosil Co., Ltd.)
-972) 0.2% by weight was adhered to the surface of the obtained toner powder. The glass transition temperature of the obtained toner powder was 55.3 ° C, and the melting start temperature was 75.6 ° C.

Example 2 Hexamethyldisiloxane was supplied in a reduced pressure fluidized bed with 15 cc / min of argon gas and 45 cc / min of argon gas, the pressure in the layer was adjusted to 0.1 Torr, and the vibration condition was 30 Hz and amplitude. It was 0.5 mm, and the hexamethyldisiloxane was plasma-polymerized on the surface of the toner powder to form a polymerized film in the same manner as in Example 1 except that the average porosity during fluidization was 0.54.

Example 3 A toner powder was prepared by a kneading and pulverizing method in the same manner as in Example 1, and only argon gas was used as a gas at 100 cc /
The toner powder was surface-treated in the same manner as in Example 1 under the same conditions as in Example 1.

Comparative Example 1 A toner for comparison was obtained in the same manner as in Example 1 except that vibration was not applied when forming the plasma polymerized film.

Comparative Example 2 The toner powder obtained in Example 1 which was not subjected to plasma polymerization and plasma treatment was used as it was for comparison.

Comparative Example 3 No vibration was applied when plasma treatment was performed, and the other examples were used.
A comparative toner was obtained in the same manner as in.

The above-mentioned Examples 1 and 2 and Comparative Example 1,
The following characteristics were evaluated using the toner powder obtained in Comparative Example 2. (1) Glass transition temperature (Tg) It was measured using a differential scanning calorimeter (manufactured by SEIKO). (2) Melting start temperature flow tester (CFT-500 type manufactured by Shimadzu Corporation)
Was measured by the constant velocity heating method (5 ° C./min). (3) Storage stability (blocking test) 20 g of the toner powder obtained in Examples and Comparative Examples
It was placed in a 00 cc glass beaker and placed in an oven controlled at a temperature of 50 ° C. After keeping the conditions for 8 hours, remove from the oven,
It was left under the condition of% RH for 24 hours. Then, the beaker was turned upside down, the toner inside was transferred onto the paper, and the appearance of the toner powder placed in a conical shape was evaluated visually and by touch. The evaluation was performed according to the following evaluation criteria. 1: Powdery, non-blocking, free-flowing. 2: There is a lump with a diameter of 3 mm or less that can be touched and crushed by a finger. 3: There is a lump with a diameter of 10 mm or less that can be crushed by touching with a finger. 4: Fixed in a lump or beaker of standard 3 or more.

(4) Non-Offset Temperature Region First, 4 parts by weight of the toner powder obtained in the above Examples and Comparative Examples and a ferrite carrier not coated with a resin (Powder Tech Co., trade name: FL-1020). 96 parts by weight were mixed to prepare a two-component developer. Next, a commercially available copying machine (manufactured by Sharp Corporation, trade name: SF
-9800), a plurality of belt-shaped unfixed images having a length of 2 cm and a width of 5 cm were prepared on an A4 transfer paper. Then, a fixing machine in which a heat fixing roll having a surface layer made of Teflon and a pressure fixing roll having a surface layer made of silicone rubber are paired and rotated, a roll pressure is 1 kg / cm ² and a roll speed is The surface temperature of the fixing roll was changed stepwise so that the toner image on the transfer paper having the unfixed image was fixed at each surface temperature. At this time, it was observed whether or not the toner was smeared in the blank area, and the temperature range in which the smear did not occur was taken as the non-offset temperature range. (5) Fixing strength In the fixing machine, the surface temperature of the heat fixing roll is 70 ° C.
Then, the temperature was set to 100 ° C., and the toner image on the transfer paper on which the unfixed image was formed was fixed. Then, after measuring the image density of the fixed image, the fixed image was rubbed with a cotton pad to measure the image density again. The obtained measured value was applied to the following formula to calculate the fixing strength. The image density was measured using a reflection densitometer RD-914 manufactured by Macbeth. Fixing strength (%) = (image density of fixed image after rubbing / image density of fixed image before rubbing) × 100 Table 1 shows the test results of the above items.

[0018]

[Table 1]

As is clear from Table 1, the toner powders obtained in Examples 1 and 2 formed a plasma polymerized film on the surface thereof, and therefore, after obtaining a sufficient fixed image and a non-offset temperature region. It was confirmed that the storage stability did not change with time as compared with the comparative example, and the effect of plasma polymerization was sufficiently maintained. It was confirmed that this toner powder had a sufficiently improved storage stability while maintaining a practically sufficient low temperature fixing property. On the other hand, in the toner powders of Comparative Examples 1 and 2, the plasma polymerized film was not formed sufficiently uniformly on the surface, so it was confirmed that the storage stability was poor and there was a practical problem. .

Further, the following characteristics were evaluated using the toner powders obtained in Example 3, Comparative Example 2 and Comparative Example 3. (6) 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 2, the surface modification of the plasma treatment of the present invention reduces the residual monomer amounts of styrene and toluene in the toner powder of Example 3 as compared with Comparative Examples 2 and 3. Was confirmed.

(7) Sensory test for odor 20 g of a sample in a polystyrene bottle having a capacity of 150 cc
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 2.

[0022]

[Table 2]

As shown in Table 2, in the case of the toner powder of Example 3 according to the modifying method of the present invention, the odor was sufficiently improved,
It was confirmed that the effect of the plasma surface treatment was sufficient.

(8) Continuous Copy Test A commercially available copying machine (manufactured by Sharp Corporation, trade name: SF-9) using the developers of Examples 1 to 3 obtained in (4) above.
800), a continuous copy test up to 5000 sheets was conducted.
The initial triboelectric charge amount and the triboelectric charge amount after copying were measured. The initial image density and the image density after continuous copying were also measured. The copy manuscript is A4 size, 10
The portion corresponding to% is the black portion. A reflection densitometer RD-914 manufactured by Macbeth was used for image density measurement.
The triboelectric charge amounts of the toner powders obtained in Examples 1 to 3 are −20 μc after the initial value after copying 5000 sheets.
/ G to −25 μc / g. The image density is
The value changed from 1.31 to 1.35. From the measurement results, the toner powders obtained in Examples 1 to 3 are
It was confirmed that it could withstand continuous copying satisfactorily and had no practical problems.

[0025]

INDUSTRIAL APPLICABILITY According to the present invention, plasma polymerization and treatment can be carried out while subjecting the powder to floating and vibration, and the surface modification and surface treatment of the powder can be performed, so that powder having various characteristics can be easily provided. You can Further, in carrying out the method, since it is possible to arbitrarily select the mixing ratio of the powder in the reduced pressure fluidized bed with a vibrating table, the uniformity of the processing temperature, and the control of the processing apparatus can be freely controlled, the powder having a fine particle diameter Various functions can be added to.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a reduced pressure fluidized bed type plasma device with a vibrating table.

[Explanation of symbols]

1 vacuum pump 2 valves 3 Fine powder recovery flask 4 Manometer 5 Reduced pressure fluidized bed 6 Pirani vacuum gauge 7 Dispersion plate 8 electrodes 9 High frequency power supply 10 shaking table 11 Vibration motor 12 Liquid monomer container 13 Flow meter 14 Non-polymerizable gas cylinder 15 Polymerizable monomer gas cylinder

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-267301 (JP, A) JP-A-6-145212 (JP, A) JP-A-3-44649 (JP, A) JP-A-63- 269168 (JP, A) JP 60-47004 (JP, A) JP 62-257175 (JP, A) JP 58-222503 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 19/08 G03G 9/087 G03G 9/10

Claims (4)

(57) [Claims] 1. A powder characterized in that a powder suspended in a polymerizable monomer gas is exposed to a plasma atmosphere under vibration to form a plasma-polymerized film of the polymerizable monomer gas on the surface of the powder. Surface modification method. 2. A modified powder surface characterized by exposing a powder suspended in a non-polymerizable gas to a plasma atmosphere under vibration to subject the surface of the powder to plasma treatment. Quality method. 3. The powder is suspended in a reduced pressure fluidized bed, and means for vibrating the powder is provided by a vibrating table in contact with the reduced pressure fluidized bed.
A method for modifying the surface of a powder as described. 4. The frequency is 10 to 2000 depending on the vibrating table.
4. The method for modifying the surface of a powder according to claim 3, wherein the reduced pressure fluidized bed is subjected to vibrations of Hz and amplitude of 0.1 to 2 mm.