JPH1095855A - Production of surface-treating resin powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smooth the surface of a resin powder and thereby to obtain a surface-treating resin powder having the surface uniformly coated with a surface-treating agent by mixing a resin powder with a surface-treating agent under stirring with a spherical mixer having a specified structure. SOLUTION: A resin powder and a surface-treating agent are mixed under stirring by using a spherical mixer which has a lower rotating blade 3 rotating along the inner bottom surface of a spherical container and an upper rotating blade 4 rotating at a peripheral speed of 40m/sec or higher at the central part of the container. A resin powder having an average particle size of 3-30μm is pref. since such a powder is easily handled regardless of how it is produced, i.e., regardless of whether it is produced by grinding, polymn., spray drying, microcapsulation, or any other method. A surface treating agent having a primary particle size in the range of from 2nm to 2μm is pref. since it facilitates the production of the surface-treated resin powder. This production process is suitable for producing an electrophtographic toner excellent in performance.

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 surface-treated resin powder in which a surface treating agent is uniformly attached to a resin powder by using a high-speed rotating spherical mixer. More specifically, the present invention provides an optimum manufacturing method when manufacturing an electrophotographic toner.

[0002]

2. Description of the Related Art Conventionally, a wet treatment method and a dry treatment method have been used as a method for attaching a fine particle surface treating agent to the surface of a resin powder having a particle size of about 1 to 100 μm. In the wet treatment method, a method is employed in which a resin powder is put into a solution in which a surface treating agent is dispersed, adhered thereto, and then the solvent is removed and dried. In the dry processing method, the surface treatment agent is adhered to the resin powder by stirring the resin powder and the surface treatment agent using a stirring mixer. In particular, the technology of attaching a surface treating agent to the surface of a resin powder has recently been used in the production of fine powdered electrophotographic toners of high quality due to the development and various functions of electrophotographic devices. Various methods based on the above-mentioned production methods have been studied.

Generally, an electrophotographic toner (hereinafter referred to as toner) is an untreated toner surface which is a resin powder obtained by blending a charge control agent, an anti-offset agent, a coloring agent, etc. in a thermoplastic resin. Is treated with a hydrophobized fine powder surface treating agent, and the performance of the toner is greatly affected by the treatment state. In particular, when the untreated toner and the surface treatment agent are mixed, the toner particles whose entire surface is treated with the surface treatment agent are different due to insufficient stirring and mixing of the toner particles. In a toner system in which toner particles partially treated are mixed, the frictional charge amount of each particle becomes non-uniform, so that image fouling called fog occurs at the time of copying, There is a disadvantage that the amount of toner collected without contributing increases.

[0004] Under this environment, the obtained toner particles also have different hydrophobicities, so that environmental stability is poor, and the image is disadvantageously susceptible to the environment during copying. As described above, the performance of the toner itself is greatly affected by the state of the surface treatment agent attached to the surface of the toner. On the other hand, the free surface treatment agent present in the toner system is related to the flow characteristics of the toner, so that the toner is not used.
Although necessary for the system, the amount is adequate to affect other properties. For example, in a toner having a large amount of a surface treatment agent having a weakly adhered state, the surface treatment agent is easily released from the toner at the time of use. Problems often arise.

That is, if the released surface treatment agent adheres to the photoreceptor, a high-quality latent image is not formed on the photoreceptor, so that the image quality deteriorates and the collected toner increases. Also, if the released surface treatment agent floats and contaminates the charger, a high-quality latent image cannot be formed on the photoreceptor or toner cannot be sufficiently transferred to paper. Similar phenomena occur such that the image quality decreases and the collection toner increases. Also, if the released surface treatment agent is not uniformly mixed and added into the toner system, the fluidity of the system will vary, and the degree of toner replenishment during copying will change. There is a problem that the image density is not constant.

Further, large aggregates of the surface treating agent are
If it is present in the system, it migrates onto the photoreceptor and causes damage to the photoreceptor, or if it is transferred to paper, the image quality deteriorates. Further, in a two-component type toner composed of a toner and a carrier, which has been widely commercialized in recent years, a toner having no corner on its surface is advantageous in terms of fluidity and generation of spent toner. These various problems all relate to the state of the toner surface, and the surface state largely depends on the method of mixing the resin powder and the surface treating agent. For this reason, a finely powdered electrophotographic toner obtained by treating the surface of a resin powder (untreated toner) with a surface treatment agent has a fluidity, a triboelectric chargeability, It is necessary to adjust the environmental stability and the like, and to process and manufacture with a hydrophobic surface treatment agent. In order to manufacture the toner, a wet method and a dry method have been conventionally used.

However, in the wet method, the solution used in the production process tends to remain in the toner system, which causes a problem of triboelectric charging and a problem of odor caused by the residual solution during use. It is necessary to completely remove the residual solution by drying. For this reason, the operation of producing the toner from the solution is extremely complicated and causes a significant reduction in workability. As a method for eliminating such disadvantages by such a wet treatment method, there is a dry treatment method in which a stirring and mixing treatment is performed in a gas phase without using a solvent. For example, there is a method in which a resin powder and a surface treating agent are charged into a jet mill or a high-speed mixer, and then stirred and mixed for treatment. However, in the dry processing method, when a jet mill is used, there are disadvantages in that the generation of jet air requires a large energy cost and it is difficult to control the temperature of the jet air freely.

In addition, in the case of a substance whose particle diameter is carefully controlled, such as toner, when a jet mill is used, if the jet air speed is high, the resin powder is pulverized and the controlled particle size distribution changes. It is not preferable because there is a possibility that it may occur.
In addition, in the case of using a Hensiel mixer or a high-speed mixer whose shape is a cylindrical mixer, the peripheral speed of the rotating blades for mixing and stirring is relatively high as compared with other mixers, so that the toner is manufactured. It is used favorably at the time. However, in Hensiel mixers and high-speed mixers,
Since the shape of the stirring vessel is a cylindrical vessel having a flat bottom, not only does the sample stay at the bottom of the vessel, but there is a drawback that the sample easily adheres to the cylindrical wall surface. Therefore, in a container of a Hensiel mixer or a high-speed mixer, it is difficult to sufficiently agitate the sample, and a uniform mixture cannot be expected. Therefore, the toner uniformly treated with the surface treating agent on the surface of the resin powder is not expected. Is difficult to obtain.

In a Hensiel mixer or a high-speed mixer, the peripheral speed of a rotary blade for stirring and mixing is at most 40 m / sec. It is difficult to uniformly adhere the resin and smooth the surface of the resin powder in a short time, which requires a long processing time. As described above, the stirring and mixing treatment is insufficient, and the surface treatment state of the individual toner particles varies, resulting in a mixture of the treated toner particles on the entire surface of the resin powder and the partially treated toner particles. In addition, since the frictional charge amount of each particle becomes non-uniform, image fouling called fog occurs at the time of copying, and the amount of toner collected without contributing to image formation increases.

[0010]

Accordingly, the present inventors have found that when applying a surface treating agent to a resin powder, the stirring efficiency is good, and it is possible to mix and disintegrate fine powder aggregates. By using the apparatus, a method for producing a surface-treated resin powder which can smoothen the surface of the resin powder by stirring and mixing and easily apply a surface treatment agent to the surface of the resin powder in a uniform state. We considered.

[0011]

That is, according to the present invention, a resin powder and a surface treating agent are provided by rotating a lower rotating blade rotating along the inner bottom surface of a spherical container and an upper rotating blade rotating at a peripheral speed of 40 m / sec or more at the center of the container. A method for producing a surface-treated resin powder obtained by stirring and mixing was established using a spherical mixer provided with rotating blades. Generally, toner (toner for electrophotography) is a fine powder obtained by blending a charge control agent, an anti-offset agent, a colorant, etc. in a thermoplastic resin, and a fine hydrophobic powder on the surface of an untreated toner. The surface treatment agent is manufactured by using a chemical surface treatment agent, and the performance of the toner greatly depends on the processing state. However, in the production of toner by the production method of the present invention, not only can the surface be uniformly treated, but also a part of the surface treatment agent is buried in the resin powder by increasing the peripheral speed of the spherical mixer. It is also possible to make it a state.

Therefore, in the toner obtained by the production method of the present invention, the surface treatment agent is hardly released, and the general disadvantages of the conventional toner have been solved. As the structure of the inner surface of the container of the spherical mixer used in the present invention, not only a true sphere but also a substantially spherical one, for example, a spherical container having an oval or elliptical cross section can be mentioned. Further, the stirring blade rotating in the container needs at least two kinds of rotating blades, a lower rotating blade rotating along the bottom surface of the container and an upper rotating blade rotating at a high speed in the central portion. As a typical example

The spherical mixer shown in FIG. 1 will be described. The spherical mixer has a sample inlet (1) and a sample outlet (2), is internally spherical, and has lower rotating blades along the spherical container bottom surface. (3) and an upper rotary wing (4) rotating at the center. The sample existing at the center of the bottom surface in the container is strongly stirred by the rotational force of the lower rotating blade (3), and is pushed up along the wall surface from the container bottom to the peripheral portion and from below to above. The sample pushed up along the container wall is spherical because the inside of the container is spherical.
It falls on the upper rotating blade (4) rotating at the center and is vigorously stirred and mixed.

At this time, when the peripheral speed of the rotating blades of the spherical mixer is increased, the surface treatment agent is uniformly shortened on the powder surface as compared with a conventional mixer of a cylindrical container, for example, a Hensiel mixer. It can be fixed in time. That is, when the upper rotating blade has a peripheral speed of 40 m / sec or more, it is possible to obtain a powder in which the surface treatment agent is uniformly fixed to the surface. In particular, when the peripheral speed of the upper rotary blade is 60 to 100 m / sec, the processing can be performed in a short time, and the characteristics of the production method of the present invention are greatly exhibited, which is preferable. When the peripheral speed of the rotating blades of the spherical mixer is increased, for example, at 80 m / sec, if the spherical mixer is cooled with cold water or the like, the adhesion of powder to the inner wall of the apparatus is reduced, and the stirring effect is also improved. It is preferable to cool appropriately. Also,

If the driving shaft (5) of the rotating wing is provided with a conical rotating shaft that spreads from the vicinity of the upper rotating part toward the bottom surface of the spherical container, the sample does not stay on the bottom part in the spherical container. For efficient stirring, the treatment is preferably performed uniformly.

The resin powder used in the production method of the present invention is produced by any method such as a pulverization method, a polymerization method, a spray drying method, a microcapsule method, as long as the average particle diameter is 3 to 30 μm. Even those which are easy to use are preferable. Particularly, in the case of toner production, resin powder (untreated toner)
When the average particle size is 3 to 15 μm, the production of the surface-treated resin powder is easy, and a toner having excellent image quality can be obtained.
The thermoplastic resin, which is one component of the resin powder of the present invention, may be any of those conventionally used in the production of various toners. For example, styrene-methyl acrylate copolymer, styrene- Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer,
Styrene copolymers such as styrene-butadiene copolymer,
Examples include polyester resin, epoxy resin, and olefin-based resin.

As the charge controlling agent, which is one component of the resin powder of the present invention, any one of conventionally used azo-based dyes, nigrosine dyes, triphenylmethane-based dyes and quaternary ammonium salts can be used. Either is acceptable. Examples of the offset preventing agent, which is one component of the resin powder of the present invention, include low molecular weight polypropylene, low molecular weight polyethylene and the like. As a colorant which is one component of the resin powder of the present invention,
Any of carbon black, benzidine yellow, quinacridone, condensed azo pigments, copper phthalocyanine and the like conventionally used in the production of toner may be used.

As the surface treating agent used as the surface treating agent in the present invention, it is preferable that the primary particle diameter is 2 nm to 2 μm, since the production method of the present invention becomes easy. In particular, when the primary particle diameter of the surface treatment agent is from 5 nm to 1 μm, a toner which is excellent in treatment and further excellent in image quality can be obtained. The surface treatment agent is not limited to one type, and two or more types can be used in combination as needed. Examples of the surface treatment agent used in the present invention include hydrophobic colloidal silica, titanium oxide, tin oxide, aluminum oxide, stearates, silicates, cerium oxide, silicon carbide, titanium carbide, barium titanate, and titanium. Fine powders such as strontium acid, acrylic acid polymer, acrylic acid ester polymer, olefin polymer, and formaldehyde condensate are exemplified. Examples and comparative examples are described below.

[0017]

【Example】

Example 1 Styrene-acrylate copolymer 100 parts by weight Carbon black 8 parts by weight Low molecular weight polypropylene 4 parts by weight Negative charge inhibitor 1 part by weight The above materials were mixed with a blender and set at 130 ° C. After cooling the kneaded material obtained by kneading with a twin screw extruder,
The resulting mixture was roughly pulverized by a hammer mill, and then finely pulverized by a pulverizer using a jet stream. The ultrafine powder in the obtained finely pulverized powder is strictly classified and removed by an air classifier, and then 5 to 20
μm was selected to obtain a black resin powder (untreated toner) having an average particle size of 11 μm. 1.0% of hydrophobic colloidal silica having a primary particle diameter of about 20 nm is added to the resin powder as a surface treatment agent,

FIG. 1 A spherical mixer having an internal volume of 40 liters described was stirred and mixed at a peripheral speed of 70 m / sec for 3 minutes while cooling to obtain a toner (toner for electrophotography).

When the surface of the toner was observed with an electron microscope, it was found that there was no angular part on the surface of the resin powder before stirring and mixing by the spherical mixer, and the surface had changed to a rounded state. Further, with respect to the hydrophobic colloidal silica in the toner system, it was observed that a part of the colloidal silica was hardly contained in the resin powder and was firmly fixed to the surface thereof. In the toner system, no large aggregate of silica that could be visually confirmed was confirmed. Then, the toner was put into a commercial plain paper copier, and subjected to a durability test of 10,000 sheets in a normal environment and a 35 Perform a durability test of 5,000 sheets in a high-temperature and high-humidity environment of ℃ -80% RH, and measure the image density, transfer rate, and contamination status in the machine under the following conditions.

[Table 1] It described in. In the following Examples and Comparative Examples,
A durability test (long-term copyability) was performed in a normal environment and in a high-temperature, high-humidity environment as in Example 1, and measured under the following conditions.

The results are shown in Table 1.

A. Image density (ID) Measured with a reflection densitometer. b. Transfer rate (%) Calculate from the following formula by measuring the amount consumed during actual shooting and the amount recovered in the recovery unit. Transfer rate (%) = (recovered amount / amount consumed during actual shooting) × 100 c. In-machine dirt Visual evaluation was made according to the following criteria. …: Good, △: contamination in the machine, ×: contamination in the machine and scratches on the photoreceptor

As shown in Table 1, the image density and transfer rate were good, no white spots were observed in the image fogging or solid black image, and no contamination in the copying machine due to scattering inside the machine was observed. When the photoreceptor and the charger were also checked, they were in a good condition without any dirt. No abnormality was found in a durability test in a high-temperature and high-humidity environment.

Example 2 The black resin powder obtained in Example 1 was

FIG. 1 A peripheral speed of 70 m while cooling the described spherical mixer
/ Sec for 3 minutes, and 0.8% of hydrophobic colloidal silica having a primary particle diameter of about 20 nm was added as a surface treating agent, and further stirred and mixed at a peripheral speed of 70 m / sec for 3 minutes to obtain a toner. . When the surface of the toner was observed with an electron microscope,
The angular portion on the surface of the resin powder before stirring and mixing by the spherical mixer disappeared, and the surface changed to a rounded state. It was observed that the hydrophobic colloidal silica on the surface was firmly fixed as in Example 1. Also, no large aggregates of silica were visually observed in the toner system. This toner was placed in a commercially available copying machine in the same manner as in Example 1, and a durability test was conducted in a normal environment and in a high-temperature, high-humidity environment. regardless of,

As shown in Table 1, good results equivalent to Example 1 were obtained. The inside of the machine was in a good condition without contamination.

Example 3 Styrene-acrylate copolymer 100 parts by weight Carbon black 7 parts by weight Low molecular weight polypropylene 3 parts by weight Negative charge inhibitor 1 part by weight From the above materials, in the same manner as in Example 1, A black resin powder having an average particle size of 10 μm selected from 5 to 20 μm was obtained. A hydrophobic colloidal silica having a primary particle diameter of about 20 nm is added to the resin powder.
0.8% added,

FIG. 1 A peripheral speed of 70 m while cooling the described spherical mixer
/ Min for 3 minutes, and then the primary particle size is
0.2% of micron aluminum oxide fine powder is added and peripheral speed is 50m
The mixture was stirred and mixed at a speed of / sec for 3 minutes to obtain a toner. Observation of the toner surface with an electron microscope revealed that there was no angular portion on the surface of the resin powder before stirring and mixing by the spherical mixer, and the surface had changed to a rounded state.

Also, hydrophobic colloidal silica on the surface
It was observed that the surface treatment agent composed of aluminum oxide was firmly adhered to the toner surface. Incidentally, no large aggregates of the surface treating agent composed of hydrophobic colloidal silica / aluminum oxide as visually observed in the toner system were found. The toner was put into a commercially available plain paper copier having a different use in Example 1, and a durability test was performed in a normal environment and a high temperature and high humidity environment.

As shown in Table 1, the image density and transfer rate were good, no image fogging and no white spots in the solid black image were observed, and no contamination in the copying machine due to scattering inside the machine was observed. Example 4 Styrene-acrylate copolymer 100 parts by weight Magnetite 50 parts by weight Low molecular weight polypropylene 3 parts by weight Negative charge inhibitor 1 part by weight

In the same manner as in Example 1, 5
A black resin powder having an average particle size of 11 μm selected from 20 μm was obtained. 1.0% of a hydrophobic colloidal silica having a primary particle size of about 10 nm, which is a mixture having a ratio of 1: 1 as a surface treatment agent, and about 1.5 μm of silicon carbide are added to the resin powder;

FIG. 1 A peripheral speed of 70 m while cooling the described spherical mixer
/ Min for 3 minutes, and then the primary particle size is
0.2% of aluminum oxide fine powder of 0.2 μm and a peripheral speed of 50
The mixture was stirred and mixed at m / sec for 3 minutes to obtain a toner. Observation of the surface of the toner with an electron microscope revealed that there was no angular portion on the surface of the resin powder before stirring and mixing by the spherical mixer, and the surface had changed to a rounded state. It was also observed that the surface treatment agent composed of hydrophobic colloidal silica and aluminum oxide on the surface was firmly adhered to the toner surface. It should be noted that no large aggregates of the surface treating agent composed of hydrophobic colloidal silica and aluminum oxide as visually observed in the toner system were found.

The toner was placed in a commercially available plain paper copier having a different use in Example 1, and a durability test was conducted in a normal environment and a high temperature and high humidity environment.

As shown in Table 1, the image density and transfer rate were good, no image fogging and no white spots in the solid black image were observed, and no contamination in the copying machine due to scattering inside the machine was observed. Example 5 100 parts by weight of polyester 9 parts by weight of magnetite 2 parts by weight of low-molecular-weight polypropylene 1 part by weight of a negatively charged inhibitor In the same manner as in Example 1, 5 to 20 μm was selected from the above materials and the average particle diameter was 10 μm. A resin powder was obtained. 1.0% of hydrophobic colloidal silica having a primary particle diameter of about 20 nm and 0.5% of polymethyl methacrylate fine powder of about 0.3 μm are added to the resin powder as a surface treatment agent,

FIG. 1 A peripheral speed of 60 m while cooling the described spherical mixer
The mixture was stirred and mixed for 5 minutes at a speed / sec to obtain a toner.

When the surface of the toner was observed with an electron microscope, it was found that the surface had changed to a rounded state. Also,
It was observed that the surface treatment agent consisting of hydrophobic colloidal silica polymethyl methacrylate on the surface was firmly adhered to the toner surface. Incidentally, no large aggregates of the surface treating agent composed of hydrophobic colloidal silica / aluminum oxide as visually observed in the toner system were found. The toner was put into a commercially available plain paper copier having a different use in Example 1, and a durability test was performed in a normal environment and a high temperature and high humidity environment described in Example 1.

As shown in Table 1, the image density and transfer rate were good, no image fogging and no white spots in the solid black image were observed, and no contamination in the copying machine due to scattering inside the machine was observed.

Example 6 The styrene-acrylic acid ester copolymer of Example 4 was changed to polyester, and 5 to 20
A black resin powder having an average particle diameter of 11 μm, of which μm was selected, was obtained. 0.5% of tin oxide type fine powder having a primary particle diameter of about 20 nm is added as a surface treatment agent to the obtained black resin powder,

FIG. 1 A peripheral speed of 60 m while cooling the described spherical mixer
The mixture was stirred and mixed for 5 minutes at a speed / sec to obtain a toner. Observation of the surface of the toner with an electron microscope revealed that there was no angular portion on the surface of the resin powder before stirring and mixing by the spherical mixer, and the surface had changed to a rounded state. Also,
It was observed that the surface treating agent composed of hydrophobic colloidal silica / polymethyl methacrylate on the surface was firmly adhered to the resin powder surface. Incidentally, no large aggregate of the surface treatment agent as visually confirmed in the toner system was found.

The toner is put into a commercial plain paper copier,
A durability test was performed in a normal environment and a high-temperature and high-humidity environment described in Example 1.

As shown in Table 1, the image density and transfer rate were good, the image density and transfer rate were good, no image fogging and white spots in the solid black image were observed, and no contamination in the copying machine due to scattering inside the machine was confirmed. Was. Example 7 100 parts by weight of polyester 4 parts by weight of magnetite The above materials were mixed well with a blender and kneaded with a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a hammer mill, and then finely pulverized using a jet stream. The ultrafine powder in the obtained finely pulverized powder was strictly classified and removed by an air classifier, and 5 to 20 μm was selected to obtain a blue resin powder having an average particle diameter of 10 μm.

The resin powder is

[FIG. 1] After stirring and mixing at a peripheral speed of 80 m / sec for 3 minutes while cooling a spherical mixer having an inner volume of 40 liters described above, hydrophobic colloidal silica having a primary particle diameter of about 20 nm is used as a surface treatment agent.
0.5% was added, and the mixture was further stirred and mixed at a peripheral speed of 60 m / sec for 2 minutes to obtain a color toner. Observation of the surface of the toner with an electron microscope revealed that the angular portion on the surface of the resin powder before stirring and mixing by the spherical mixer had disappeared, and the surface had changed to a rounded state. Further, a state was observed in which the hydrophobic colloidal silica was firmly fixed to the surface of the resin powder. In the toner system, large aggregates of silica that could be visually confirmed were not confirmed. The toner was put into a commercially available color copier, and subjected to a durability test in a normal environment and in a high temperature and high humidity environment. Went,

As shown in Table 1, a clear cyan image having a high density was obtained, and there was no decrease in image quality such as an increase in fog, and no contamination in the copying machine due to scattering inside the machine was observed. In addition, when the photoreceptor and the charger were confirmed, they were in a good condition without contamination.

Comparative Example 1 The same operation as in Example 1 was performed, except that the spherical mixer used in Example 1 was changed to a 40-liter Henschel mixer having an inner volume of 70 m / sec and the peripheral speed was changed to 70 m / sec. Observation of the surface of the obtained toner with an electron microscope revealed that many irregularities on the surface were square. In addition, hydrophobic colloidal silica was not found to be fixed on the surface of the resin powder,
Agglomerates of hydrophobic colloidal silica were observed in the toner system. The toner was put into the plain paper copying machine used in Example 1 and subjected to a durability test in a normal environment.

As shown in Table 1, the transfer rate was reduced, and in terms of image quality, fog occurred and white spots were observed in solid black, and an image which was not practically acceptable was obtained. When the inside of the copying machine was inspected, contamination inside the machine due to scattering inside the machine was confirmed. Further, in a high-temperature and high-humidity environment, the transfer rate was further reduced, and the occurrence of fog and contamination in the apparatus were further worsened.

Comparative Example 2 The same operation as in Example 4 was carried out except that the spherical mixer used in Example 4 was changed to a 40-liter Henschel mixer having an inner volume of 30 m / sec and the peripheral speed was changed to 30 m / sec. Observation of the surface of the obtained toner with an electron microscope revealed that many irregularities on the surface were square. Further, no state was observed in which hydrophobic colloidal silica and silicon carbide as surface treatment agents were fixed to the toner surface, and aggregates of the surface treatment agent were observed in the toner system. The toner was put into the copying machine used in Example 4, and in a normal environment,

As shown in Table 1, the transfer rate was low, and in terms of image quality, fog and dust around characters and white spots in black solid were observed, and an image which was not practically acceptable was obtained. Further, the inside of the copying machine was significantly contaminated as compared with Example 4, and the surface of the photoreceptor was also markedly scratched. Further, in a high-temperature and high-humidity environment, the transfer rate was further reduced, and the occurrence of fog and contamination in the apparatus were further worsened.

Comparative Example 3 The same operation as in Example 6 was performed except that the spherical mixer used in Example 6 was changed to a 40-liter Henschel mixer having an inner volume of 40 m / sec and the peripheral speed was changed to 30 m / sec. Observation of the surface of the obtained resin powder with an electron microscope revealed that many irregularities on the surface were square. Further, hydrophobic colloidal silica and fine powder of tin oxide, which are surface treatment agents, are used as toners.
No fixation to the surface was observed, and aggregates of the surface treating agent were observed in the toner system. The toner was put into the commercial copying machine used in Example 6, and a durability test was performed in a normal environment.

As shown in Table 1, the transfer rate was low, and in terms of image quality, fog, dust around characters, and white spots were observed in solid black, and an image which was not practically acceptable was obtained. Also,
The inside of the copying machine was significantly contaminated compared to Example 6, and the surface of the photoreceptor was markedly damaged. Further, in the high-temperature and high-humidity environment test, the transfer rate was further reduced, and the occurrence of fog and contamination in the machine were further deteriorated.

Comparative Example 4 The same operation as in Example 7 was performed except that the spherical mixer used in Example 7 was replaced with a 40-liter Henschel mixer having an inner volume of 40 m / sec and the peripheral speed was changed to 30 m / sec. . Obtained toner
As a result of observing the surface of the sample with an electron microscope, many irregularities were observed on the surface. Further, no state was observed in which the hydrophobic colloidal silica as the surface treating agent was fixed to the resin toner surface, and aggregates of the surface treating agent were observed in the toner system. The toner was put into the commercially available color copier used in Example 7, and the durability test in a normal environment showed that

As shown in Table 1, an image having a non-uniform image density, a lot of fog, and a low reproducibility of fine lines, which was not practically acceptable, was obtained.
Further, the dirt condition in the copying machine was significantly contaminated compared to Example 7, and the surface of the photoreceptor was also markedly scratched. Furthermore,
In the test in a high-temperature and high-humidity environment, the image quality and the state of occurrence of scratches on the surface of the photoreceptor were further deteriorated as compared with those in a normal temperature environment.

[0033]

According to the production method of the present invention, the use of the spherical mixer makes it possible to easily and uniformly adhere (fix) the surface treating agent to the core resin powder as compared with the conventional method. It has become. In particular, according to the production method of the present invention, the surface treatment agent is easily adhered (fixed) to an untreated toner which is a resin powder in the state of producing the toner for electrophotography in a uniform state, and the obtained toner is obtained. When-is used in a copying machine, the present invention provides a toner exhibiting excellent effects such as image quality, in-machine contamination, transfer rate, long-term copying property and environmental friendliness.

[0034]

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a configuration example of a spherical mixer main body used in the present invention.

[Explanation of symbols]

 1. 1. Sample inlet 2. Sample outlet Lower rotating wings 4. 4. Upper rotating wings Rotary wing drive shaft

Claims (4)

[Claims] A resin powder and a surface treating agent are supplied to a lower rotating blade rotating along the inner bottom surface of a spherical container and a peripheral speed of 40 to a central portion of the container.
A method for producing a surface-treated resin powder obtained by stirring and mixing using a spherical mixer provided with an upper rotary blade rotating at m / sec or more. 2. The resin powder according to claim 1, which has an average particle size of 3
A method for producing a surface-treated resin powder having a size of from 30 μm to 30 μm. 3. A method for producing a surface-treated resin powder according to claim 1, wherein the surface-treating agent has a primary particle diameter of 2 nm to 2 μm. 4. A method for producing a surface-treated resin powder, wherein the surface-treated resin powder according to claim 1, 2 or 3 is an electrophotographic toner.