JPH0372371A - Toner for developing electrostatic latent image and production of master batch therefore - Google Patents

Abstract

PURPOSE:To obtain the master batch dispersed finely and uniformly with dyes and pigments in a resin by previously dissolving the resin in a solvent to prepare a resin soln., then grinding and dispersing the dyes and pigment with this resin soln. and removing the solvent from this mixture. CONSTITUTION:The binder resin is previously dissolved into the org. solvent to prepare the resin soln. and after the dyes and pigments are ground and dispersed in the resin soln., the solvent is removed from this mixture. The binder resin includes arbitrary resins used for toners. Org. solvents which dissolve the binder resin and with which the dyes and pigments to be used are wet well are preferable as the org. solvent to be used to prepare the resin soln. Since the dyes and pigments have a high polarity, the solvent to be used has preferably a polar group in the molecule. Any powdery or granular dyes and pigments which are used as coloring agents and/or electrostatic charge control agents for production of the toners are used as the dyes and pigments. The master batch finely and uniformly dispersed with the dyes and pigments in the resin is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a masterbatch and a method for manufacturing a toner for developing electrostatic latent images using such a masterbatch.

Conventionally, in the electrophotographic method, an electrostatic latent image is formed on a photoreceptor by various methods, and then this electrostatic latent image is developed using a developer containing toner. A generally known method is to transfer the obtained image onto paper or the like and fix it using heat, light, or the like. Furthermore, as a method for removing toner remaining on the photoconductor, a method is generally known in which a cleaning member is brought into contact with the surface of the photoconductor, as typified by a blade cleaning method.

Various methods for developing the electrostatic latent image are already known, and are roughly divided into two-component development methods and one-component development methods. The specific charge of toner, that is, the amount of charge per unit weight of toner, has a large effect on image quality.

Two-component development methods, such as the cascade method and the magnetic brush method, are widely employed, and a developer made of a mixture of toner and carrier particles is used to develop an electrostatic latent image. In such a two-component development method, when the specific charge of the toner is excessively small, the electrostatic interaction with the carrier is small, so the toner is scattered by agitation of the toner and carrier in the developing machine. This may contaminate the area around the developing machine, or the toner may adhere to areas other than the image on the photoreceptor during the developing process, causing so-called background fog.

On the other hand, when the toner has an excessively large specific charge, the amount of toner adhering to the electrostatic latent image on the photoreceptor is small, resulting in a decrease in image density. Therefore, when the fineness and dispersion of dyes and pigments in toner particles are insufficient, image density becomes unstable, background smudges, and bleeding occur, as well as toner filming on the photoconductor and contamination inside the developing machine. arise.

On the other hand, in the -component development method, magnetic toner is usually used, and the toner particles are charged by friction between them or with a developing sleeve. However, in general, according to this method, the triboelectric charging of the toner tends to become unstable, and in addition, the amount of charging of the toner is significantly smaller than that in the above-mentioned normal two-component development method. Therefore, when toner with low specific charge is mixed,
This causes a decrease in image density, toner scattering, blurring, unevenness of the image, etc., and the image characteristics become unstable. In particular, in addition to the above, the -component development method has a large initial instability in that the initial image density is low and several hundred copies are required until an image of a predetermined density is provided. Lowering the developing bias in order to increase the image density is not preferable because it causes background fog.

As described above, in both the two-component development method and the one-component development method, the chargeability of the developer has a large effect on image quality, and therefore, it is important for individual toner particles to have equal specific charges to produce high-quality images. It is extremely important for the stable formation of In order to obtain such a toner, various ingredients, especially dyes and pigments, must be sufficiently finely divided and uniformly dispersed in the toner. When the fineness and dispersion of dyes and pigments in toner particles are insufficient, in addition to the aforementioned instability of image density, background smearing, and bleeding, toner filming on the photoreceptor and contamination inside the developing machine may occur. arise.

However, according to conventionally known toner manufacturing methods, it is difficult to finely and uniformly disperse dyes and pigments, such as charge control agents, in the toner.

That is, conventionally, toner used for electrophotography, electrostatic printing, etc. is usually produced by mixing dyes and pigments and other compounding materials together with a binder resin under high-speed stirring, and then passing this mixture through a twin-screw extruder or heated knee gun. , melt-kneaded using means such as heated rolls,
After cooling the kneaded product thus obtained, it is pulverized and, if necessary, classified to have a predetermined particle size, thereby producing the product. Furthermore, if necessary, the toner is subjected to surface treatment using colloidal silica or the like.

Here, conventionally used dyes and pigments often contain particles larger than the particle size of the required toner particles, and such dyes and pigments cannot be used in the conventional methods as described above. , not sufficiently refined. Therefore, according to conventional manufacturing methods, the product toner particles may not contain a predetermined amount of dye and pigment, or the toner particles may contain individual particles of dye and pigment, resulting in various problems as described above. The problem arises.

Therefore, in order to solve this problem, for example, Japanese Patent Application Laid-Open No. 62-30259 discloses that a part of the binder resin and a dye/pigment are melt-kneaded in advance, cooled, and then pulverized to form a master batch. Then, this master hatch was melted and kneaded again with the remaining binder resin, cooled, and crushed.
Methods of manufacturing toner have been proposed.

However, in this method, the binder resin generally has low polarity, whereas many dyes and pigments have high polarity. It is chemically essentially difficult to disperse finely and uniformly in the liquid.

Furthermore, in cases where a master hatch is not used, dyes and pigments are used in larger amounts than necessary, but such methods do not essentially solve the above-mentioned problems, and moreover, dyes and pigments are generally Since it is expensive, it unnecessarily increases the manufacturing cost of toner.

On the other hand, JP-A-61-156054 discloses that after dissolving a part of the binder resin and a charge control agent in a solvent, the solvent is removed, and then this is melt-kneaded together with the remaining binder resin. A method of manufacturing toner by pulverization has been proposed. However, in general, many charge control agents are poorly soluble in solvents, and therefore, in order to obtain a resin solution containing the required amount of charge control agent, a large amount of solvent is required, which is disadvantageous in practice. .

The present invention was made in order to solve the various problems mentioned above in conventional toner production. It is an object of the present invention to provide a method for manufacturing toner particles, and a method for manufacturing a masterbatch that can be suitably used for manufacturing such toner.

First, according to the present invention, (a) dissolving the binder resin in an organic solvent to prepare a resin solution; (b) dissolving the binder resin in the resin solution; There is provided a method for producing a masterbatch, which comprises the steps of: pulverizing and dispersing dyes and pigments; and (c) removing the solvent from the mixture.

Furthermore, according to the present invention, (a) a step of dissolving the binder resin in an organic solvent to prepare a resin solution, (b) a step of crushing and dispersing the dye and pigment in the resin solution, (c ) removing the solvent from the above mixture to obtain a masterbatch; (d) further adding a binder resin and, if necessary, a characteristic imparting agent to the above masterbatch and kneading the mixture to produce a kneaded product; There is provided a method for producing a toner for developing electrostatic latent images, which comprises the step of (e) pulverizing the kneaded material to a required particle size to obtain a toner.

In the present invention, the binder resin includes any resin conventionally used in toners, such as styrene,
-Methylstyrene, m-methylstyrene, p-methylstyrene, p-chlorostyrene, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic acid n-octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n methacrylate -butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, One or more (co) radically polymerizable monomers such as glycidyl acrylate, glycidyl methacrylate, acrylic acid, methacrylic acid, 2-vinylpyridine, 4-vinylpyridine, etc.
Polymers may be mentioned.

In particular, in the present invention, polystyrene or a copolymer of styrene and an acrylic ester such as butyl acrylate or a methacrylic ester such as butyl methacrylate is preferably used.

The organic solvent used in preparing the resin solution is as follows:
It is preferable that the binder resin is dissolved and the dye and pigment used are well wetted by this solvent. That is, since dyes and pigments generally have high polarity, the solvent used preferably has a polar group in the molecule. Therefore, such solvents include:
For example, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, alcohols such as propanol and butanol, and ethers such as tetrahydrofuran are preferably used. A mixture of these solvents is also preferably used. However, when the dye and pigment used have relatively low polarity, aromatic hydrocarbons such as toluene and xylene are also preferably used. Furthermore, a mixed solvent of the above alcohols and these hydrocarbons can also be used. However, the solvent used in the present invention is not limited to the above.

According to the present invention, in preparing the resin solution, 1 to 40 parts by weight of the binder resin, based on 100 parts by weight of the organic solvent,
Preferably, 5 to 20 parts by weight are used. Note that the resin solution is usually prepared by dissolving a pre-produced resin in a solvent, but the resin solution can also be prepared by polymerizing required monomers in a solvent. In such a case, unreacted monomers may remain in the resin solution, but there is no particular problem.

Next, as the dye/pigment, for example, any powdered or granular dye/pigment that has been conventionally used as a colorant and/or a charge control agent in the production of toner can be used. These include metal-containing dyes and pigments and organic acid metal salts, and specific examples include, in addition to carbon black, organic pigments such as phthalocyanine pigments, and the following formula (X- represents an anion species): A nigrosine dye containing an electron-donating dye such as the nigrosine dye shown below, (wherein, X' represents a cationic species) (wherein, X' represents a cationic species) (Hodogaya Chemical Industry■
Electron-accepting dyes such as metal complex salts of monoazo dyes shown in

According to the present invention, such dye and pigment are added to the resin solution,
After pulverizing and dispersing in a resin solution, the resulting mixture is desolvented to obtain a masterbatch.

When pulverizing and dispersing the dye and pigment in the resin solution, the dye and pigment should be added in an amount of 1 to 4 parts by weight per 100 parts by weight of the solvent in the resin solution.
0 parts by weight, preferably 5 to 20 parts by coul. Further, as a means for pulverizing and dispersing the dye and pigment in the resin solution, for example, an ordinary wet pulverizer such as a Pall mill or an annular wet pulverizer can be used.

In the pulverization and dispersion of the dye and pigment in the resin solution, a dispersion stabilizer for the dye and pigment can be used. As such a dispersion stabilizer, for example, ethylene-vinyl acetate copolymer or the like is suitably used.

Furthermore, an electrolyte having a lower interfacial tension with water than the resin used can also be used. Thus, when using a dispersion stabilizer, it is preferable that the solvent has low polarity.

Thereafter, the mixture of the dye and pigment and the resin solution is desolventized by common means such as heating drying, vacuum drying, freeze drying, etc. to obtain a masterbatch. If necessary, the obtained masterbatch may be crushed or crushed.

In this way, a masterbatch in which the dye and pigment are uniformly and finely dispersed in the binder resin can be obtained. According to the method of the present invention, the dye and pigment are finely and uniformly dispersed in the binder resin even if the dye and pigment initially contain particles larger than the particle size of the intended toner. That is, the dye and pigment are usually uniformly dispersed in the resin with a particle size of about 5 μm or less, preferably about 1 am.

-M, masterbatch refers to a coloring material in which a pigment is dispersed and mixed in a resin to be colored at a high concentration, and conventionally,
As mentioned above, it is manufactured by melt-kneading blended materials such as resin and dyes and pigments in the absence of a solvent, cooling the resulting kneaded product, and then crushing or granulating it. However, in this method, resins generally have low polarity, but many dyes and pigments have high polarity, so even if the resin and dyes and pigments are melt-kneaded, the dyes and pigments are finely mixed into the resin. Difficult to disperse uniformly.

Therefore, according to the present invention, a resin solution is prepared by dissolving the binder resin in an organic solvent, and then, the dye and pigment are crushed and dispersed in this resin solution, and then the solvent is removed. A masterbatch in which dyes and pigments are finely and uniformly dispersed in a binder resin can be obtained.

Next, according to the present invention, in step (d), a binder resin and, if necessary, a property imparting agent are added to the masterbatch obtained as described above, and the mixture is kneaded. The toner can be obtained by manufacturing and then, in step (e), pulverizing this hydrogen mixture to a required particle size.

The binder resin used in step (d) may be the same as or different from the binder resin used in the production of the masterbatch, but if different, the binder resin used in step (a) must be compatible with the resin used in step (a). Good things are desirable.

Examples of the characteristic imparting agent include a magnetic material for imparting magnetism to the toner, a polyolefin wax for imparting offset resistance to the toner, and the like. Moreover, the dyes and pigments mentioned above can also be used as characteristic imparting agents.

As the polyolefin wax, for example, polyethylene wax or polypropylene wax is suitably used. Further, as the magnetic material, for example, magnetic oxides such as ferrite and magnetite, or various magnetic metals are used.

These magnetic materials are usually 30 to 300 parts by weight, preferably 30 to 100 parts by weight, per 100 parts by weight of the binder resin. 1
Used within the scope of this section.

In step (d) above, to further add a binder resin and, if necessary, a characteristic imparting agent to the masterbatch and knead it, use a normal kneading means such as a roll, Nigoo, Banbury roll, extruder, etc. I can do it.

In addition, in order to crush the obtained kneaded material, air flow crushing method etc.
It can be done by normal means. If necessary, classification may be performed after this pulverization. In this way, a toner having the required particle size can be obtained.

Further, according to the present invention, the obtained toner particles may be surface-treated with colloidal silica or the like.

When the toner according to the present invention is used in a two-component development system, a substance known as a carrier, which is well known in the electrostatic electrophotographic technical field, is added to the toner and used as a two-component developer. In this two-component developer, the amount of toner blended is in the range of 2 to 20% by weight, preferably 5 to 10% by weight. Examples of carriers include iron powder,
Ferrite powder, magnetite powder, powder made of a composite of resin and magnetic material, etc. are used. Furthermore, a so-called coach carrier can also be used. However, it is not limited to these.

As described above, according to the present invention, a resin solvent is prepared by dissolving a resin in a solvent in advance, and then dyes and pigments are pulverized and dispersed in this resin solution, and then this mixture is Since the dye and pigment are dispersed in the resin by removing the solvent, a masterbatch in which the dye and pigment are finely and uniformly dispersed in the resin can be obtained.

Furthermore, according to the present invention, if such a masterbatch is further kneaded with a binder resin and, if necessary, a property-imparting agent, and after cooling is ground to the required particle size, the dye/pigment and property-imparting agent are incorporated into the resin. Finely and uniformly dispersed toner can be obtained.

Therefore, in such a toner, the distribution of the specific charge amount is substantially uniform, it has stable image density over a long period of time, it is possible to provide a copy image without background smudge, and the dye and pigment on the photoreceptor are There is no adhesion or filming, and sufficient image density can be obtained by using a small amount of dye and pigment.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 1 part by weight of nigrosine dye (Nigrosine Hose EX manufactured by Orient Chemical Industry Co., Ltd.) as a charge control agent and 0.4 parts of ethylene-vinyl acetate copolymer (Soaprene CH manufactured by Nippon Gosei Chemical Industry Co., Ltd.) as a dispersion stabilizer. Parts by weight were added to 10 parts by weight of xylene, and the dye was ground in a ball mill for 50 hours.

Separately, 80 parts by weight of styrene and 20 parts by weight of butyl methacrylate were copolymerized in xylene using abbisisobutyronitrile as a polymerization initiator. 2.
A solution of a low molecular weight styrenic copolymer having a glass transition point of 72° C. and an acid value of 0.1 was prepared.

Separately, 60 parts by weight of styrene and 40 parts by weight of butyl methacrylate were subjected to bulk polymerization, and then solution polymerized in the presence of xylene, resulting in a weight average molecular weight of about 3.0×10!
A solution of a styrene-based high molecular weight copolymer having a glass transition point of 60'' and an acid value of 0.1 was prepared.

Therefore, the solution of the styrene-based low molecular weight copolymer and the solution of the styrene-based high molecular weight copolymer are mixed in an equal weight ratio, and the dispersion of the charge control agent is added thereto, and the mixture is stirred.
Thereafter, this mixture was heated under reduced pressure to remove the solvent and obtain a lump. This lump was pulverized to obtain a masterbatch containing a charge control agent.

Next, 101 parts by weight of this masterbatch (1 part by weight of binder resin)
00 parts by weight and 1 part by weight of a charge control agent. ), 3 parts by weight of low molecular weight polypropylene (Viscol 550P manufactured by Sanyo Kakai Industries ■) as an anti-offset inhibitor, 1.5 parts by weight of carbon black (MA-8 manufactured by Mitsubishi Chemical Industries ■) and magnetite powder (manufactured by Toda Industries ■). EPT-500)6
After mixing 0fi parts and melt-kneading in a twin-screw extruder,
It was pulverized using a jet pulverizer. Next, the particles were classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.

The obtained toner was applied to a commercially available plain paper electrostatic copying machine (NP-150, manufactured by Canon ■), and 10,000 sheets were continuously copied, and the images were evaluated. The results are shown in Table 1. Also,
FIG. 1 shows the relationship between the number of copies and image density. According to this toner, even after 10,000 copies were made, clear and beautiful images without background stains could be stably obtained. Furthermore, no filming was observed on the photoreceptor.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was investigated. The results are shown in Figure 4. Measurement is done by Hosokawa Micron ■
The measurement was carried out using a charge distribution measuring device manufactured by Manufacturer Co., Ltd. It is shown that the developer according to the invention has a narrow charge distribution.

Example 2 3 parts by weight of the same nigrosine dye as in Example 1 and 1.2 parts by weight of ethylene-vinyl acetate copolymer were added to 30ffi of xylene!
The dye was ground in a ball mill for 50 hours.

A solution of the same styrene-based low molecular weight copolymer and a styrene-based high molecular weight copolymer solution as in Example 1 were mixed in an equal weight ratio, and the above dispersion of the charge control agent was added thereto and mixed by stirring. This mixture is then heated under reduced pressure to remove the solvent,
A lump was obtained. This lump was pulverized to obtain a masterbatch containing a charge control agent.

Next, 103 parts by weight of this masterbatch (1 part by weight of binder resin)
00 parts by weight and 3 parts by weight of a charge control agent. ), 3 parts by weight of the same low molecular weight polypropylene as in Example 1, 1.5 parts by weight of carbon black, and 60 parts by weight of magnetite powder were mixed, melt-kneaded in a twin-screw extruder, and then pulverized in a jet pulverizer. . Next, the particles were classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.

Using the obtained toner in the same manner as in Example 1, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 1 shows the relationship between the number of copies and image density. According to this toner, even after 10,000 copies were made, clear and beautiful images without background stains could be stably obtained.

Furthermore, no filming was observed on the photoreceptor.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was investigated. The results are shown in FIG. 4, indicating that the developer according to the present invention has a narrow charge distribution.

Example 3 Same as Example 1, 3 parts by weight of nigrosine dye and 1.2 parts by weight of ethylene-vinyl acetate copolymer were added to 30 parts by weight of xylene, and the dye was ground in a ball mill for 50 hours.

The same solution of the styrene-based low molecular weight copolymer as in Example 1 and the solution of the styrene-based high molecular weight copolymer were mixed at equal weight ratios. A dispersion of the charge control agent is added to the resulting mixture of the resin solution at a ratio of 1 part by weight of the charge control agent to 10 parts by weight of the resin solid content in the resin solution, and the mixture is stirred and mixed. Thereafter, this mixture was heated under reduced pressure to remove the solvent and obtain a lump. This lump was pulverized to obtain a masterbatch containing a charge control agent.

Next, 11 parts by weight of the thus obtained masterbatch (consisting of 10 parts by weight of the binder resin and 1 part by weight of the charge control agent) was added with the above styrene-based low molecular weight copolymer and the styrene-based high molecular weight copolymer. 90 parts by weight of a styrene-butyl methacrylate copolymer resin consisting of a mixture in equal weight ratio with the polymer, 3 parts by weight of the same low molecular weight polypropylene as in Example I, 1.5 parts by ffi of carbon black, and 60 parts by weight of magnetite powder.
Parts by weight were mixed, melt-kneaded using a twin-screw extruder, and then pulverized using a jet pulverizer. Next, it was classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.
In the same manner as above, using the obtained toner, 100 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 1 shows the relationship between the number of copies and image density. According to this toner, even after 10,000 copies,
It was possible to stably obtain clear and beautiful images without background smudges.

Furthermore, no filming was observed on the photoreceptor.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was examined. The results are shown in Figure 4. It is shown that the developer according to the invention has a narrow charge distribution.

Example 4 3 parts by weight of monoazo chromium dye (Spiron Black TRH manufactured by Hodogaya Chemical Industry Co., Ltd.) as a charge control agent and Example 1
1.2 parts by weight of the same ethylene-vinyl acetate copolymer was added to 30 parts by weight of xylene, and the dye was ground in a ball mill for 50 hours.

A solution of the same styrene-based low molecular weight copolymer and a styrene-based high molecular weight copolymer solution as in Example 1 were mixed in an equal weight ratio, and the above dispersion of the charge control agent was added thereto and mixed by stirring. This mixture is then heated under reduced pressure to remove the solvent,
A lump was obtained. This lump was pulverized to obtain a masterbatch containing a charge control agent.

Next, 103 parts by weight of this masterbatch (1 part by weight of binder resin)
00 parts by weight and 3 parts by weight of a charge control agent. ), 3 parts by weight of the same low molecular weight polypropylene as in Example 1, and 10 parts by weight of carbon black were mixed, melt-kneaded in a twin-screw extruder, and then pulverized in a jet pulverizer. Next, the particles were classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.

Using the obtained toner in the same manner as in Example 1, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 3 shows the relationship between the number of copies and image density. According to this toner, even after 10,000 copies were made, clear and beautiful images without background stains could be stably obtained.

Further, no filming was observed on the photoreceptor.

Comparative Example 1 Styrene-butyl methacrylate consisting of 1 part by weight of the same nigrosine dye as in Example 1 and an equal weight ratio mixture of the styrene-based low molecular weight copolymer prepared in Example 3 and the styrene-based high molecular weight copolymer. 100 parts by weight of copolymer resin, 3 parts by weight of the same low molecular weight polypropylene as in Example 1, 1.5 parts by weight of carbon black, and 60 parts by weight of magnetite powder were mixed and melted and kneaded in a twin-screw extruder, followed by a jet pulverizer. It was crushed. Next, the particles were classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.

Using the obtained toner in the same manner as in Example 1, 10
000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1, and the relationship between the number of copies and image density is shown in FIG. According to this toner, after 100 copies were made, there was significant background smudge, and clear and beautiful images could not be obtained.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was investigated. The results are shown in Figure 5. This developer is shown to have a broad charge distribution.

Comparative Example 2 A toner was prepared in the same manner as Comparative Example 1 except that 3 parts by weight of nigrosine dye was used as a charge control agent.

Using this toner, 10,000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 2 shows the relationship between the number of copies and image density. According to this toner, after 10,000 copies were made, there was significant background smudge, and clear and beautiful images could not be obtained. Also, filming on the photoreceptor was observed.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was examined. The results are shown in Figure 5. This developer is shown to have a broad charge distribution.

Comparative Example 3 1001 ift parts of the toner prepared in Comparative Example 2 was mixed with 1 part by weight of cerium oxide to prepare a developer.

Using this developer, 10,000 sheets were continuously copied and the images were evaluated. The results are shown in Table 1. Further, FIG. 2 shows the relationship between the number of copies and image density. According to this toner, an image with stable density could not be obtained.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was investigated. The results are shown in Figure 5. This developer is shown to have a broad charge distribution.

Comparative Example 4 1 part by weight of monoazo chromium dye (Spiron Black TRH manufactured by Hodogaya Chemical Industry Co., Ltd.) as a charge control agent, 100 parts by weight of styrene-acrylic acid copolymer (Himer TB~1000 manufactured by Sanyo Chemical Industry Co., Ltd.) 3 parts by weight of the same low molecular weight polypropylene as in Example 1 and 10 parts by weight of carbon black were mixed, melt-kneaded in a twin-screw extruder, and then pulverized in a jet pulverizer. Next, the particles were classified using an air classifier to prepare a toner having a particle size of 5 to 20 μm.

0.3 parts by weight of silicic acid fine powder (Aerosil R-972 manufactured by Aerosil Co., Ltd.) was mixed with 100 parts by weight of this toner, and this was mixed with a carrier (EFV250 manufactured by Nippon Steel Powder ■) so that the toner concentration was 6% by weight. A developer was prepared by mixing.

This developer was applied to a commercially available plain paper copying machine (Sanyo Electric (1 Kiku 5F)
T-1102Z), 10,000 sheets were continuously copied, and the images were evaluated. The results are shown in Table 1. Further, FIG. 3 shows the relationship between the number of copies and image density. According to this developer, after 10,000 copies were made, there was significant background fog in the images.

Furthermore, it was not possible to obtain a copied image with a density that was stable over time.

Further, a developer was prepared with a toner concentration of 5% by weight relative to the carrier, and the triboelectric charge distribution of the toner was examined. The results are shown in Figure 6. It is shown that the developer according to the invention has a narrow charge distribution.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the number of copies and image density when images are copied using the developer obtained by the method of the present invention, and FIG. A graph showing the relationship between the number of copies and image density,
FIG. 3 is a graph showing the relationship between the number of copies and image density when images are copied using the developer according to the present invention and a developer as a comparative example. FIG. 4 is a graph showing the relationship between the number of copies and image density obtained by the method according to the present invention. FIG. 5, a graph showing the triboelectric charge distribution of the developer, shows the rg! of the developer as a comparative example. FIG. 6 is a graph showing Ffi and triboelectric charge amount distribution for the developer according to the present invention and a developer as a comparative example. Figure 1

Claims (3)

[Claims] (1) (a) A step of dissolving the binder resin in an organic solvent to prepare a resin solution, (b) A step of crushing and dispersing the dye and pigment in the resin solution, (c) A step of removing the above mixture. A method for producing a masterbatch, comprising a step of using a solvent. (2) (a) A step of dissolving the binder resin in an organic solvent to prepare a resin solution, (b) A step of crushing and dispersing the dye and pigment in the resin solution, (c) A step of removing the above mixture. (d) further adding a binder resin and, if necessary, a characteristic imparting agent to the masterbatch and kneading the mixture to obtain a masterbatch; (e) producing a kneaded product by kneading the masterbatch; and (e) producing a kneaded product. A method for producing a toner for developing an electrostatic latent image, the method comprising the step of pulverizing the toner to a required particle size to obtain a toner. (3) Claim 3, wherein the characteristic imparting agent is a magnetic powder, a charge control agent and/or an anti-offset imparting agent.
A method for producing a toner for developing an electrostatic latent image as described in .